ML20205P092
| ML20205P092 | |
| Person / Time | |
|---|---|
| Issue date: | 01/31/1999 |
| From: | NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | |
| References | |
| NUREG-1620, NUREG-1620-DRFT, NUREG-1620-DRFT-FC, NUDOCS 9904200018 | |
| Download: ML20205P092 (200) | |
Text
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. Draft Standard Review Plan PUBLIC DOCUMENT ROOM for theReview of a Reclamation Plan for f,' Mill Tailings Sites Lnder Title II of the L ranium g Mill Tailings Radiation
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' pd%d U.S. Nuclear Regulatory Commission ,TN Office of Nuclear Material Safety and Safeguards ! )
Washington, DC 20555-0001 \,,,,,/
9904200018 990131 R PDR
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Drwft Standard Review Plan l for the Review of a I Reclamation Plan for Mill Tailings Sites Under l Title II of the Uranium Mill Tailings Radiation .
Control Act l
l Draft Report for Comment Manuscript Completed: December 1998 l Date Published: January 1999 i
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Division of Waste Management OfUce of Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 l
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COMMENTS ON DRAFT REPORT Any interested pany may submit comments on this report for consideration by the NRC staff.
Comments may be accompanied by additional relevant information or supporting data. Please specify the report number draft NUREG-1620 in your comments, and send them by May 7,1999 to:
Chief, Rules Review and Directives Branch U.S. Nuclear Regulatory Commission Mail Stop T6-D59 Vvasbington, DC 20555-0001 You may also provide comments at the NRC Web site, http://www.ntc. gov. See the link under " Technical Reports in the NUREG Series" on the " Reference Library" page.
Instructions for sending comments electronically are included with the document, NUREG-1620, Draft, at the web site.
For any questions about the material in this report, please contact:
Banad Jagannath Mail Stop: TWFN 7 J-8 '
U.S. Nuclear Regulatory Commission Wahhington, DC 20555-0001 8
Phone: 301-415-6653 E-mail: BNJ
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CONTENTS
! Eage 1.0 B AC KGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 l
l l 2.0 ROLES OF INVOLVED ORGANIZATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.1 U.S. Nuclear Regulatory Commission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.2 Uranium Mill Licensees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.3 Custodial Agency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 l 2.4 S tate s . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . 3 3.0 THE LICENSE TERMINATION PROCESS . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1 Licensee Documentation of Completed Remedial and Decommissioning Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1.1 Documentation of Completed Surface Remedial Actions . . . . . . . . . 3 L 3.1.2 Documentation of Completed Site Decommissioning . . . . . . . . . . . . 4 3.1.3 Documentation of Completed Ground-water Corrective Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.2 NRC Review of Completed Closure Actions . . . . . . . . . . . . . . . . . . . . . . . . 5 3.3 Observational Periods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 i 3.3.1 Following Completion of Surface Remedial Actions . . . . . . . . . . . . . 5 3.3.2 Ground-water Remediation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.4 Long-Term Site Surveillance Funding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.4.1 Bases for Determination of Surveillance Charge . . . . . . . . . . . . . . . . 7 1 3.4.2 Determination of Surveillance Charge Amount . . . . . . . . . . . . . . . . . 8 3.4.3 Payment of Long-Term Surveillance Charge . . . . . . . . . . . . . . . . . . . 9 i
I 3.5 Preparation of the Long-Term Surveillance Plan . . . . . . . . . . . . . . . . . . . . 10 I i I il
3 6 Site Ready for License Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.7 Termination of the Specific License / Issuance of the General License . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ......11 3.7.1 NRC Determination under Section 83c/274c of the Act ............ ........11 3.7.2 NRC Review and Acceptance of the LTSP . . . . . . . . . . . . . . . . . . . . 12 3.7.2.1 Issuance of a Specific Order under 10 CFR 40.28 . . . . . . . . . . . . . 12 3.7.3 Transfer of Site Control to the Custodial Agency . . . . . . . . . . . . . . . 13 4.0 ADDITIONAL IS SUES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.1 UMTRCA Title II Sites on Indian Lands . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.2 Concurrent Jurisdiction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.0 REFERENCES
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F ABSTRACT A Nuclear Regulatory Commission source and byproduct material license is required by 10 CFR Part 40 for the operation of uranium mills and the disposition of " tailings," wastes produced by the ,
extraction or concentration of source material from ores processed primarily for their source material.
l Appendix A to Part 40 establishes technical and other criteria relating to siting, operation, decontamination, l
decommissioning, and reclamation of mills and of tailings at mill sites. The licensee's site reclamation plan documents how the proposed activities demonstrate compliance with the criteria in Appendix A to Part 40 and the information needed to prepare the environmental report on the effects of the proposed reclamation activities on the health and safety of the public and on the environment.
This Standard Review Plan (SRP) is prepared for the guidance of staff reviewers in the Office of Nuclear Material Safety and Safeguards in performing safety and environmental reviews of reclamation plans for uranium recovery sites covered by Title II of the Uranium Mill Tailings Radiation Control Act. It provides guidance for new reclamation plans, renewals, and amendments. The p-incipal purpose of this SRP is to ensure the quality and uniformity of staff reviews and to present a well-defined base from which to evaluate changes in the scope and requirements of a review.
This SRP is written to cover a variety of site conditions and reclamation plans. Each section provides a I description of the areas of review, review procedures, acceptance criteria, and evaluation of findings.
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' B STRACT . . . . . . . . . . . . . . ..... ... ..... ....... . ...................iii LIST OF ABBREVIATIONS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x i s
1.0 GEOLOGY AND SEISMOLOGY . . . . . . .................................1-1 1.1 Stratigraphic Features .. . . . . . . . . . ...............................1-1 1.2 Structural and Tectonic Features .. . ... . .. ... ........ . . . . . . . . .. . .1-3 1.3 Geomorphic Features . . . . .. . .1 -5 1.4 Seismicity.. . . . . . . . . . .. . . 1 -7 2.0 GEOTECHNICAL STABILITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2- 1 2.1 Site and Uranium Mill Tailings Characteristics ...........................2-1 2.2 Slope Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5 2.3 Settlement ......... ........ ............ ..... ... ............ .. 2-14 2.4 Liquefaction Potential .............................................2-18 2.5 Disposal Cell Cover Engineering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21 2.6 Construction Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-25 2.7 D. .posal Cell Hydraulic Conductivity.. ... ... .... . . . . . . . . . .. ..2-29 3.0 SURFACE WATER HYDROLOGY AND EROSION PROTECTION . . . . . . . . . . . . . . . . 3-1 3.1 Hydrologic Description of Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2 3.2 Flooding Determinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3 3.3 Water Surface Profiles, Channel Velocities, and Shear Stresses . . . . . . . . . . . . . . . . 3-8 3.4 Erosion Protection Design ....... ... . . .. . . . . . . . . . ........................3-9 3.5 Design of Unprotected Soil Covers and Vegetated Soil Covers... . .. . . ...3-15 3.6 General References... ... .... . .... ..... .. ...... .... .... ... . . . . . . ..... 3-17 4.0 WATER RESOURCES PROTECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 4.1 Site Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 4.2 Ground-water Protection Standards . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . 4-17 4.3 Hazard and ALAR Assessment for Alternate Concentration Limits . . . . . . . . . . 4-20 l 4.4 Ground-water Corrective Action and Compliance Monitoring PN.. . . ... . ... .. .. 4-33 5.0 RADON A'ITENUATION AND SITE CLEANUP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1 5.1 Radon Attenuation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5- 1 5.2 Processing Site Cleanup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5-9 5.3 Radiation Safety Controls and Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-13 I
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CONTENTS (cont'd)
APPENDICES PAGE A. GUIDANCE TO THE NRC STAFF FOR REVEWING HISTORICAL ASPECTS OF SITE PERFORMANCE FOR LICENSE RENEWALS AND AMENDMENTS ..... ... Al B. GUIDANCETO THE NRC STAFF ON THE USE OF STANDARD STATISTICAL HYPOTHESIS TESTING ............. . .. .... ............. .. ... . ....... .. ... . . ........... . .. . ... .... .... .. B I C. OUTLINE RECOMMENDED BY THE NRC STAFF FOR PREPARING SITE-SPECIFICFACILITY RECLAMATION AND STABILIZATION COST ESTI? MI ES FOR REVEW ...... ........ .. ....... ...... . . . ...... .... .... .... . ..... . ..... ...... ..... ... C I D. GUIDANCE TO THE NRC STAFF ON REVEWING LONG-TERM SURVEILLANCE PLANS... .. ............... ... .. ....... . . . . . . . . . . . . . .......................DI E. GUIDANCE TO THE NRC STAFF ON THE LICENSE TERMINATION PROCESS FOR CONVENTIONAL URANIUM MILL LICENSEES.. .. .... ..... . .... ...... ............ . ... .El F. GUIDANCE TO THE NP'. STATT ON EFFLUENT DISPOSAL AT LICENSED URANIUM RECOVERY FACILITIES; CONVENTIONAL MILLS.. .... .... ... . .. . ........ ... ..F1 G. NATIONAL HISTORIC PRESERVATION ACT AND ENDANGERED SPECES I
ACT CON S ULTATION S .. .. . ... . . . .. ...... ..... ... .. ... .. . .. . ... .. .. . .. .. . . . .... ...... ... .. . ........... ..... .. .... . .. ... G I i
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l FIGURE Page Schematic cf Nuclear Regulatory Commission licensing and inspection process and applicability to different license documents . ... ...... .. .. . . . . . . . xiv i
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0 1 g TABLES Page 4.1.3-1 Common Uranium Mill Chemical Constituents . .. . . . .. . . ..4-8 I1 I
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LIST OF ABBREVIATIONS ACHP Advisory Council on Historic Preservation Act ACL alternate concentration limit l
AEA Atomic Energy Act of 1954 as amended j ALARA as low as reasonably achievable {
ASTM American Society of Testing and Materials j BLM U.S. Bureau of Land Management j CAP corrective action program CCR construction completion report CFR Code of FederalRegulations CPI Consumer Price Index !
DOE U.S. Department of Energy EA environmental assessment EIS environmental impact statement l EPA U.S. Environmental Protection Agency J ER environmental report l ESA Endangered Species Act !
FEMA U.S. Federal Emergency Management Agency FONSI finding of no significant impact FSTP final staff technical position GEIS generic environmental impact statement ISRM Intemational Society of Rock Mechanics LTSP long-term surveillance plan MCE maximum credible earthquake MCL maximum concentration limits MOU memorandum of understanding NHPA National Histone Preservation Act NMSS Office of Nuclear Materials Safety and Safeguards (NRC)
NRC U.S. Nuclear Regulatory Commission OSP Office of State Programs (NRC)
PHA peak horizontal acceleration PMF probable maximum flood PMP probable maximum precipitation POC point of compliance POE point of exposure QA quality assurance QC quality control RAI request for additionalinformation RfD reference dose RP reclamatiou plan RSD risk-specific dose SFCG Standard Format and Content Guide of License Applications SHPO State Historical Preservation Officer SRP Standard Review Plan TDS total dissolved solvent TER technical evaluation report ix NUREG-1620 l
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TVA Tennessee Valley Authority UMTRCA Uranium Mill Tailings Radiation Control Act of 1978 as amended L
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INTRODUCTION A Nuclear Regulatory Commission (NRC) source and byproduct material license is required under the pravisient of Title 10 of the U.S. Code of Federal Regulations, Part 40 (10 CFR Pan 40), " Domestic Licensing of Source Material," in conjunction with uranium or thorium milling, or with byproduct material at sites formerly associated with such milling. At the termination of a uranium mill license, the l mill tailings impoundment and some land will be tumed over to the Depanment of Energy (DOE),
another Federal Agency designated by the President, or the State where the site is located for long-term care. Under the Atomic Energy Act, the NRC is required to determine if all applicable requirements have been met at the time oflicense termination. Requirements applicable to a license include the regulations in 10 CFR Part 40, Appendix A, and any license condition.
1 An application for a new license, license renewal, or an amendment to or termination of an existing license should include, as appropriate, proposed specifications relating to the milling operations, and the information on the disposition of tailings or wastes resulting from such milling activities. General guidance on (1) contents of an application and filing an application and (2) producing an environmental report (ER) is provided in 10 CFR 40.31, " Application for Specific Licenses," and in 10 CFR Part 51,
" Environmental Protection Regulations for Domestic Licensing and Related Regulatory Functions,"
respectively. The information in the application is used by staff to determine whether the proposed l activities will be protective of public health and safety and be environmentally acceptable. General provisions for issuance, amendment, transfer, and renewal of licenses are described in 10 CFR Part 2, Subpan A.
The purpose of this Standard Review Plan (SRP) is to give the staffin the Office of Nuclear Material j Safety and Safeguards (NMSS) specific guidance on the review of reclamation plans and license ;
l amehdments related to reclamation plans. The reclamation . plan (RP), submitted by an applicant (in the case of a new application) or a licensee (in the case of an amendment to a previously approved reclamation plan or termination of an existing license) should demonstrate compliance with the applicable criteria in Appendix A to Part 40. The principal purpose of the SRP is to provide guidance to the NRC staff to ensure a consistent quality and rniformity in NRC reviews of RPs. Each section in this SRP contains guidance on what is to be reviewed, the basis for the review, how the staff review is to be !
accomplished, what the staff will find acceptable in a demonstration of compliance with the regulations, !
and the conclusions that are sought regarding compliance with the 10 CFR Pan 40. This SRP is intended to cover only those aspects of the NRC regulatory mission related to the reclamation of mill tailings impoundment including ground water cleanup at conventional uranium mills. As such, the SRP helps !
focus the staff review on determining if a tailings impoundment can be constmeted, operated, and ]
reclaimed in compliance with the applicable NRC regulations. The SRP is also intended to make I information about regulatory matters widely available to improve communication, and to help interested !
membus of the public and uranium recovery industry gain a better understanding of the staff's review process.
For license amendments, the focus of the review should be on the changes proposed in the amendment (see Appendix A for guidance on reviewing historical aspects of site performance). Reviewers should noueview previously accepted actions if they are not part of the proposed amendment, unless the !
review of the amendment package identifies an impact on previously accepted actions. l l
For changes to previously approved RPs, the licensee need only submit information pertinent to the i
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proposed change. The licensee need not resubmit a complete RP covering all aspects of site reclamation, )
but should present information on the proposed changes to the previoudy approved plan and its updates i as identified in the current NRC-accepted license. Reviewers should alm analyze the inspection history and operation of the site to see if any major problems have been identified over the course of the license term that would impact reclamation. The operating history of the facility is often a valuable source of information concerning the adequacy of site characterization, the acceptability of radiation protection and monitoring programs, and other data that may irm ace the staff's determination of compliance.
Appendix A to the SRP provides guidance for reviev d these historical aspects of facility performance.
If the changes are found to be acceptable, then the license is amended to identify the revised reclamation I plan as the required design for reclamation.
License termination usually involves a confirmation that all applicable requirements have been met.
This includes ensuring completion of stabilization work for the tailings consistent with the accepted reclamation plan, and a determination that all standards applicable to groundwater cleanup have been met. As such, the information in this review plan will be used to help make the necessary conclusions concerning license termination in three ways. First, this SRP will provide guidance on how the reclamation and groundwater cleanup plans will be reviewed to deternine if they are in compliance with requirements of Part 40, appendix A. Second, the SRP will assist the reviewers in determining if construction has been done consistent with the accepted design. InformaGon for this review is provided in a Constmetion Completion Report, as supplemented by NRC inspection of constmetion. Finally, the )
SRP gives guidance on what needs to be done to determine if the groundwater cleanup program has 1 achieved its objective of restoring any contaminated groundwater to applicable standards. Compliance with these three aspects of reclamation. *aken together, form the basis for the staff finding that the design and groundwater cleanup program meet applicable requireme' u and that the design and cleanup program have been acceptably completed at the sites. Thus, the applicable requirements have been met.
I The products that will be prepared by the staff to document the review will be a technical evaluation report (TER), and an environmental assessment (EA). Preparation of an EA is required under the provisions of 10 CFR 51.20 unless: (1) the staff finds, based on the EA, that NRC needs to prepare an )
environmental impact statement (EIS); (2) an EIS is needed by another Federal agency also involved in the action as a cooperating agency; (3) an EIS would be needed because of controversy at the site; or (4)
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the action is categorically excluded from the necessity to prepare an EA by 10 CFR 51.22. Applications for new mills require the preparation of a EIS per 10 CFR 51.20.
is important to note that the acceptance criteria laid out in this SRP are for the guidance of NMSS staff osponsible for the review of applications. Review plans are not substitutes for the Commission's )
regulations, and compliance with a particular SRP is not required. Methods and solutions different from those set out in the SRP may be acceptable if they provide a basis for the findings requisite to the issuance or continuance of a license by NRC.
GENERAL REVIEW PROCEDURE A licensing review is not intended to be a detailed evaluation of all aspects of facility operations.
Specific information about implementation of program or construction of a design outlined in an application is obtained through the NRC review of procedures and operations done as part of the ;
l inspection function. The differences between licensing reviews and inspections is shown in the schematic that follows this introduction. For a new license application, the staff will review the NUREG-1620 xii l I
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i proposed reclamation plan and groundwater program for compliance with the criteria in Appendix A to Part 40. For a license renewal or an amendment to an existing license, only proposed changes to the NRC-approved RP will be reviewed for compliance with criteria in Appendix A to Pan 40. If the changes proposed have an adverse impact on the performance or functionality of some of the approved features at the site, then those items will be reviewed for their compliance with regulations.
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In the case of amendment application that deals with confirmation of site or groundwater cleanup, or completion of construction, the reviewer will focus on ensuring that the applicable activities have been completed ceasistent with the RP accepted earlier. Reviewers will not revisit accepted designs or plans unless the as-completed activity shows problems such as degradation or reconformation. l l
Changes to existing licensed activities and conditions require the issuance of an appropriate license j amendment. An application for such an amendment should describe the proposed changes in detail, and I should discuss the potential environmental and health and safety impacts. Amendment requests should be reviewed using the appropriate sections of this document for guidance. Appendix A to this SRP provides guidance for examining the historical aspects of facility operations in connection with amendment reviews.
The steps of the RP review are described in the following paragraphs.
Acceptance Review The staff will conduct an acceptance review of a new RP or changes to a previously approved plan to determine the completeness of the information submitted. The RP will be considered acceptable for docketing if the information provided is complete, reflects an adequate reconnaissance and physical examination of the regional and site conditions, and provides appropriate analyses and design ;
information to demonstrate that the applicable regulatory criteria will be met. Completeness of the ER will be determined using the information requirements in 10 CFR 51.45. The staff should complete the acceptance review and transmit the results to the applicant within 30 days of the receipt of the epplication, along with a projected schedule for the remainder of the review. In this transmittal, the staff should identify any additional information needed to make the RP or ER complete. Detailed technical questions, although not required, can be included, if they are identified during the acceptance review. If the contents of the RP or ER do not clearly demonstrate compliance with applicable regulatory criteria, then the staff may decline to docket the RP and return it for revisions. j Detailed Review Following completion of the acceptance review, the staff will conduct a detailed technical review of the I
RP. During the detailed review,if there is a need for additional information, the staff will send to the licensee a request for additional information (RAI) identifying the issue or concern, bases for the concern, and the kind of information needed to resolve the concern. After receipt of satisfactory ,
response to the staff RAI, the detailed review will be concluded. The results of this review and the basis I for acceptance or denial of the requested licensing action are documented by NRC in a TER and in an EA (10 CFR 51.30) if there is a Finding Of No Significant Impact (FONSI), or an EIS (10 CFR 50.31)if the RP is part of an application for a new mill or one of the other requirements for a EIS have been met (10CFR 51.20). The detailed review should evaluate the environmental, economic, and technical i evidence provided by the applicant to support the ability of the preposed facility to meet applicable regulatory requirements. In the case of amendments to an existing license as a result of changes to a previously approved RP, the need for an EA will be detemtined on a case-by -case basis.
In determining the acceptability of any aspect of tailings reclamation, the staff will evaluate the use of )
alternatives to meeting the specific requirements in part 40, appendix A. In evaluating the use of citernatives, the staff will determine if the proposed reclamation design satisfactorily demonstrates the xv NUREG-1620
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requisite requirements of economic benefit and equivalent protection. Alternatives that have been found to be acceptable hy the staffin previous reviews have been identified in this SRP. Alternatives developed by licensees need not be limited to those discussed here. Others c in be proposed as long as the economic benefit and equivaler.t protection can be demonstrated.
The Standard Review P!an The SRP is written so as to cover a variety of site conditions and reclamation designs. Each section provides the complete procedure and acceptance criteria for all the areas of review pertinent to that section. For any given application, the staff reviewer may select and emphasize particular aspects of each SRP section as appropriate for the RP. Because of this, the staff may not carry out, in detail, all of review steps listed in each SRP section, in the review of every RP.
I. Areas of Review This subsection describes the scope of the review (i.e., what is being reviewed). It contains a brief description of the rycific technical information and analyses in the RP that need to be reviewed by each technical reviewer.
II. Review Procedures This subsection discusses the appropriate review technique. It is generally a step-by-step procedure that the reviewer uses to determine whether the acceptance criteria have been met.
III. Acceptance Criteria This subsection delineates criteria that can be applied by the reviewer to determine the acceptability of the applicant's compliance demonstration. The technical bases for these criteria have been derived from 10 CFR Parts 40 and 20, NRC regulatory guides, general design criteria, codes and standards, NRC branch technical positions, standard testing methods (e.g., American Society for Testing and Materials (ASTM) standards), technical papers, and other similar sources. These sources typically include >
solutions and approaches previously determined to be acceptable by the staff for making compliance determinations for the specific area of review. These acceptance criteria have been defined so that staff reviewers can use consistent and well-documented approaches for review of all RPs. In the absence of I
well-defined acceptance criteria, the staff will rely on " professional judgment" and what is normally l practiced in the profession. Licensees may take approaches to demonura*.ing compliance that aru l different from those in this SRP. However, they should recognize ti es is the case for regulat.ny ,
guides, substantial staff time and effort have gone into the development of these procedures and criteria, j and a corresponding amount of time and effort may be required to review and accept new or different solutions and approaches. Thus, licensee proposed solutions and approaches to safety problems or safety-related design areas other than those described in this SRP may experience longer review times and NRC requests for more extensive supporting information. The staff is willing to consider proposals for other solutions and approaches on a generic basis, apart from a specific review, to avoid the impact of the additional review time for individual cases.
IV. Evaluation Findings NUREG-1620 xvi
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l This subsection presents general conclusions and findings of the staff that result from review of each area of the RP as well as an identification of.he applicable regulatory requirements. Conclusions and findings for a specific site and review area are dependent on the site characteristics ar.d type of licensing action being considered. For each SRP section, a conclusion is included, in the Technical Evaluation Report / Safety Evaluatior. Report or in the EA/EIS, in which results of the review are published. These documents contain a description of the review; the basis for the staff findings, including aspects of the review selected or emphasized; where the reclamation design or the licensee's plans deviate from the criteria stand in the SRP; and the evaluation findings.
SRP Undates The SRP will be revised and updated periodically as the need arises to clarify the content or correct errors and to incorporate modifications approved by NRC management. A revision number and publication date are printed at a lowcr corner of each page of the SRP. Since individual sections will be revised as needed, the revision numbers and dates may not be the same for all sections..
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i xvii NUREG-1620
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,l 1.0 GEOLOGY AND SEISMOLOGY I
The RP and its supporting documents must contain sufficient regional and site-specific geologic and seismologic information related to the proposed disposal site and reclamation design, including regional and site-specific stratigraphy, structure, geomorphology, and seismology. The SRP establishes the requirements for NRC staff to conduct and document the review of new reclamation plans for mill ;
I tailing , impoundments, or amendments to previously approved reclamation plans in the areas of geology and seumology.
1.1 STRATIGRAPHIC FEATURES ;
1.1.1 Areas of Review i The staff shall review information presented in the RP on the regional and site-specific stratigraphy. The review shall include the description of surface and subsurface strata and the interpretation of their origin, occurrence, thickness, composition, age, and relationship. Review of the stratigraphic infonnation shall be coordinated with the evaluation of the site's geotechnical stability, surface water and erosion protection, and gmundwater resources protection information as described in SRP Chapters 2,3, and 4, j respectively. The purpose of this review is to determine if there has been an acceptable characterization of site and regional stratigraphy such that sufficient information has been provided for use in the RP and ,
design of the tailings cell. !
1.1.2 Review Procedures The reviewer shall examine the description and discussion of the regional and site-specific features to determine if a thorough evaluation of the regional and site stratigraphy has been presented. 1 The following specific descriptive information shall be reviewed to determine its adequacy for characterizing the regional and site-specific stratigraphic features:
(1) Description of regional stratigraphic units by rock classification and type; (2) Distribution of regional stratigraphic units; (3) Age relationships of regional and site-specific stratigraphic units; and (4) Detailed site stratigraphy based on borings conducted to determine rock types and their texture, composition, distribution, and thickness; The staff's determination of compliance shall be based in part on professional judgment, considering the complexity of the subsurface conditions at the site.
1.1.3 Acceptance Criteria 1-1 NUREG-1620
,, c The characterization of regional and site stratigraphy will be acceptable if the information provided meets the following criteria:
(1) The regional and site stratigraphy are defined in sufficient detail to provide an adequate understanding of the site-specific subsurface characteristics, including descriptions of major stratigraphic units and their orientations, age relationships, thicknesses, and distribution; (2) Stratigraphic units are described in sufficient detail to provide input to a geotechnical stability analysis; (3) Descriptions of regional and site-specific stratigraphic units provide sufficient information for input to an analysis of groundwater resources and the protection thereof; (4) Regional stratigraphic information is discussed in sufficient detail to support site-specific j information; (5) Descriptions of the regional and site stratigraphy are based on published literature and site data and conform to standard geological classifications; (6) Discussions of regional stratigraphy are adequately referenced and supponed by published reports, maps, logs, and cross sections; (7) Site descriptions are based on field investigations and sampling to define properties of surface and subsurface materials at the site; and (8) Maps show the locations of all site explorations, such as borings, geophysical surveys, trenches, and sample locations.
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Where insufficient information is provided to support interpretations and conclusions, the reviewer will request additional investigations or data gathering. The staff determination of compliance shall be based in part on professionaljudgment, considering the complexity of the site conditions.
I 1.1.4 Evaluation Findings I i
If the staff's review, as described in SRP Section 1.1, results in the acceptance of the characterization of regional and site stratigraphy, the following conclusions may be presented in the TER.
The NRC has completed its review of the information concerning the characterization of the regional and l site stratigraphy at the facility. This review included an evaluation using the review procedures in SRP Section 1.1.2 and acceptance criteria outlined in SRP section 1.1.3.
The licensee has acceptably described the stratigraphic features by providing a description of the site and regional stratigraphy using published information and information collected for the specific purpose of supporting determinations of geotechnical stability and groundwater analyses at the site. Data gathering, investigations, and analyses have used acceptable standards and practices. Data and interpretations are presented to allow effective incorporation mto gectechnical and groundwater analyses.
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On the basis of information and analysis provided in the application, and the detailed review conducted of the characterization of the regional and site stratigraphy at the facility, the NRC staff has concluded that the characterization of the regional and site stratigraphy is sufficient to support a determination that the following requirements of 10 CFR Part 40, Appendix A have been met: (1)
Criterion 4(e), which requires that the impoundment not be located near a capable fault on which a maximum credible earthquake (MCE) larger than that which the impoundment could be reasonably expected to withstand might occur;(2) Criterion 5G(2), which requires that the applicant provide information regarding the characteristics of the underlying soil and geologic formations; and (3)
Criterion 6(1) which requires that the design of the disposal facility provide reasonable assurance of control of radiological hazards to be effective for 1,000 years, to the extent reasonably achievable, and, in any case, for at least 200 years.
1.2 STRUCTURAL AND TECTONIC FEATURES 1.2.1 Areas of Review The staff shall review information presented in the RP on the regional and site-rpecific structural and tectonic setting. The review shall include definition of surface and subsurface structural and tectonic features and the interpretation of their origin, occurrence, age, and potep6al impacts, if any, on the stability of the site. Review of the structural and tectonic information shall be coordinated with the evaluation of the site's geotechnical stability, surface water and ero:aon protection, and groundwater resources protection information as described in SRP Chapters 2.3,and 4, respectively. The purpose of the review is to determine if sufficient information has been provided to establish ground acceleration values that are part of the design basis for the tailings disposal cell.
1.2.2 Review Procedures The reviewer shall examine data resulting from regional and site-specific investigations. This may include analyses of photogrammetric data, results of field reconnaissance and detailed mapping, review of pertinent literature, and geophysical data and studies to determine if a through evaluation has been presented. Features that should be considered in the review include structural features such as faults and fractures, crustal deformation, and volcanic features that may impact the site stability or groundwater conditions.
The following specific descriptive information shall be reviewed to determine its adequacy for characterizing the regional and site-specific structural features necessary to support the evaluations of reclamation system performance:
(1) Description and location of regional structural features based on published information and field reconnaissance; (2) Description and location of site subsurface structural features from sources such as available borings, drill logs, geophysical logs and data, and existing literature; l
1-3 NUREG-1620
1 (3) Description of any volcanic features such as flows, cones, plugs, or dikes located in the site )
region; (4) Age relationships of regional and site-specific structural and tectonic features; (5) Discussion of published literature containing interpretations of any of the information in items j 1,2,3, and 4, above.
The staff's determination of compliance shall be based in pan on professional judgment, considering the complexity of the subsurface conditions at the site.
1.2.3 Acceptance Criteria The characterization of regional and site structural features will be acceptable if the infonnation provided it meets the following criteria:
(1) Descriptions of regional and site-specific structural and tectonic features are based on published literature and gathered data; (2) Regional structurri and tectonic features, panicularly faults, are defined in sufficient detail to provide an adeqt anderstanding of the structural geologic conditions in the region surrounding the site which may have a likelihood of impacting the site stability or groundwater regime, 3 l
(3) Site-specific structural and tectonic features, panicularly faults, are described in sufficient detail to provide adequate information for an analysis of the site stability. Information provided should address the uncertainties and variability within the site area and the potential impacts on the disposal facility; (4) The structural and tectonic province or provinces that influence the site seismichy are identified and described; (5) The tectonic history of the pertinent province (s) is discussed in sufficient detail to suppon an analysis of the potential for disruption of the site by tectonic activity; (6) Discussions are adequately referenced and are supported by maps, logs, and cross sections showing locations of all site explorations and surveys, and depicting surface and subsurface structural and tectonic features; and (7) Descriptions include discussions of age relationships of structural and tectonic features. {
Where insufficient information is provided to support interpretations and conclusions, the reviewer will request additional investigations or data gathering. The staff determination of compliance shall be based in part on professional judgment, considering the complexity of the site conditions.
l 1.2.4 Evaluation Findings !
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If the staff's review, as described in SPS Section 1.2, results in the acceptance of the characterization of the structural and tectonic features of the region and site, the following conclusions may be presented in the TER.
The NRC has completed its review of the information related to the characterization of structural v.d tectc.nic features at the facility. This review included an evaluation using the review procedures in SRP Section 1.2.2 and acceptance criteria outlined in SRP Section 1.2.3.
The licensee has acceptably described the regional and site-specific structural and tectonic features by providing discussions and interpretations of data and reports pertinent to the subject area, which may have an impact on the site or tailings disposal system. Information provided includes a description of any faults capable of dismption of the site and any other information necessary to suppon an analysis of the geotechnical stability or groundwater conditions at the site. In addition, the staff concludes that the licensee has used acceptable methods of investigation to support its conclusions.
On the basis of the information and analysis provided in the application, and the detailed review conducted of the characterization of the structural and tectonic features at the facility, the NRC staff has concluded that the information is sufficient to support a determination that the following requirements of 10 CFR Part 40, Appendix A have been met: (1) Criterion 4(e), which l requires that the impoundment not be located near a capable fault that could cause an MCE larger than l that which the impoundment could reasonably be expected to withstand; (2) Criterion 5G(2), which requires that the applicant provide information on the characteristics of the underlying soil and geologic formations, including significant discontinuities and fractures that may impact the transport of contaminants; and (3) Criterion 6(1), which requires that the design of the disposal facility provide reasonable assurance of control of radiological hazards to be effective for 1,000 years, to the extent !
I reasonably achievable, and, in any case, for at least 200 years.
l 1.2.5 References l
None i 1.3 GEOMORPHIC FEATURES 1.3.1 Areas of Review The staff shall review the information presented in the RP on the regional and site-specific geomorphic l features. The review shall include an analysis of regional and local landforms to determine evidence for l
geomorphic processes that may impact the long-term stability of the site, including information to support an evaluation of the potential for any destmetive geomorphic processes, such as mass wasting, extreme erosion, and stream encroachment. Review of the geomorphic information shall be coordinated with the evaluation of the site's geotechnical stability and surface water and erosion protection information as described in SRP Chapters 2 and 5, respectively. The results of this review will be used to determine the acceptability of the design during operation and long-term stabilization.
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r 13.2 Review Procedures The reviewer shall examine the description and discussion of the regional and site-specific geomorphic information to determine if a thorough evaluation has been presented. Information should be detailed enough for the reviewer to make a determination regarding the geomorphic stability of the site.
The following specific descriptive information shall be reviewed to determine the acceptability of the assessment of the regional and site-specific geomorphology as it relates to geomorphic stability of the site:
(1) Description of the physiographic (geomorphic) province (s) in which the site is located, including a discussion of the distinguishing characteristics such as elevation and relief.
(2) Discussion of the active processes, such as erosion, masc wasting, and stream encroachment, within the site region and the nature and extent of those percesses.
(3) Topographic maps depicting geomorphic surfaces, physiographic provinces, landforms, drainage networks, rivers, surficial geologic units, areas of subsidence, and geomorphic hazards.
(4) Aerial photographs of the site area.
(5) Discussion of the age, occurrence, and origin of geomorphic features, in particular thot.e that may adversely affect site stability.
133 Acceptance Criteria The characterization of regional and site geomorphic features and geomorphic stability will be acceptable if the information provided meets the following criteria:
(1) Descriptions of the regional and site-specific geomorpbHogy and geomorphic processes include information sufficient to allow the reviewer to assess the nature and extent of major active processes which may modify the present-day topography of the geomorphic province (s) and the site area.
(2) The geomorphic features, particularly potential geomorphic hazards, are clearly delineated on topographic base maps of adequate scale to enable the reviewer to assess their occurrence and distribution.
(3) Descriptions are adequately referenced and are supported by published reports and maps or site data.
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(4) The regional and site-specific geomorphology and geomorphic processes are described in sufficient detai! to support an analysis of the geomorphic and geotechnical stability of the site.
Where insufficient information is provided to support interpretations and conclusions, the reviewer will request additional investigations or data gathering. The staff determination of compliance shall be based I in part on professionaljudgment, considering the complexity of the site conditions. ,
l 1.3.4 Evaluation Findings l
If the staff's review, as described in SRP Section 1.3 results in the acceptance of the l characterization of the geomorphic features of the region and site and provides information sufficient to support an assessment of the geomorphic stability, the following conclusions may be presented in the TER. !
The NRC has completed its review of the information related to the characterization of geomorphic features at the facility. This review included an evaluation using the review i procedures in SRP Section 1.3.2 and acceptance criteria outlined in SRP Section 1.3.3. l The licensee has acceptably described the geomorphic features by providing an adequate description of regional and site geomorphology using published infonnation and information collected for the specific purpose of supporting determinations of the stability of site. Data gathering, investigations, and analyses have used acceptable standards and practices. Data and interpretations are presented to allow effective incorporation into other site analyses.
On the basis of the information and analysis provided in the application, and the detailed review conducted of the characterization of the geov orphic features and stability at the facility, the NRC staff has concluded that tne characterization of the geomorphic features is sufficient to support a determination that the information provided by the licensee is sufficient to support a determination that the following requirements of 10 CFR Part 40, Appendix A have been met: (1)
Criterion 5G(2), which requires that the applicant provide information regarding the characteristics of the underlying soil and geologic formations; and (2) Criterion 6(1), which requires that the design of the disposal facility provide reasonable assurance of control of radiological hazards to be effective for 1,000 years, to the extent reasonably achievable, and, in any case. for at least 200 years.
1.3.5 References None 1.4 SEISMICITY 1.4.1 Areas of Review The staff shall review information presented in the RP on the regional and sh-specific seismicity. The review :, hall include an assessment of whether or not an adequate basis for determination of the vibratory l
ground motion, or peak horizontal acceleration (PHA) , at the site due to seismic events has been provided. Review of the regional and site-specific seismic information will focus on the stability of the 1-7 NUREG-1620
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site and will be coordinated with the geotechnical stability review and the evaluation of the stability of the design. The pumose of this review is to determine the potential for impacts to the site from seismic l events. The reviewer will determine whether the information provided is sufficient to suppon an i analysis of the design for the operational and closure periods.
i j 1.4.2 _ Review Procedures l
l The reviewer shall examine the description and discussion of the regional and site-specific information I to determine if a thorough evaluation of the potential for seismic activity has been presented. The 3 l information should be sufficient to enable the reviewer to determine the vibratory ground motion, or PHA, at the site due to seismic events.
I l The following specific descriptive information shall be reviewed to determine the acceptability of the l characterization of the seismicity and the assessment of the stability of the site and geotechnical design:
1 l (1) A listing of all recorded canhquakes that have occurred in the tectonic province or provinces l and would be expected to produce appreciable ground motion at the site. This listing should include the date of occurrence of the earthquake, its magnitude, and the location of the '
epicenter. Since earthquakes have at times been reported in terms of parameters such as intensity at a given location, cr effect on ground, structures, and people at a specific location, some of this information may have to be estimated by use of appropriate empirical relationships; (2) A listing of canhquakes, magnitude 6.2 or greater, in adjacent tectonic provinces; (3) Data obtained by standard photogeologic analysis and field reconnaissance of the study area and from review of the peninent literature; (4) An association of epicenters or locations of highest intensity of historic canhquakes with tectonic sts wtures, where possible. Epicenters or locations of highest intensity that cannot be reasonably identified with tectonic structures should be identified with tectonic provinces.
(5) ' Maps on which the locations of epicenters of historic earthquakes, associated tec:onic structures, and tectonic provinces have been depicted.
The staff's determination of compliance shall be based in part on professional judgment, considering the complexity of the regional and site-specific seismicity. The review will focus on the determination of the maximum credible earthquake (MCE), as required by Part 40, Appendix A, Criterion 4(e), unless an alternative method of determining ground motion is presented as allowed in the introduction to Appendix A. One such alternative to the MCE is a probablistic seismic hazard analysis (PSHA), presented in Section 1.4.3, below.
1.4.3 - Acceptance Criteria The information provided concerning the regional and site-specific seismicity will be acceptable if it contains sufficient detail to allow the staff to determine the vibratory ground motion, or PHA, at the site due to seismic events and to funher use that determination to assess the geotechnical stability of the site NUREG-1620 1-8
.l and the potential for impacts to ;urface and groundwater conditions at the site. In conducting this review, the staff will consider either a deterministic or a probabilistic seismic hazard analysis as an acceptable method for selecting the PHA for a site. An analysis of the geotechnical stability of the design proposed in the RP will be based on the resultant PHA. The Chapter 2, Geotechnical Stability, of this SRP contains a discussion of how the licensee may propose alternative designs in order to meet the criteria for long-term stability.
Determinist.ic Analysis For a deterministic analysis, the potential site ground motion from capable faults within the site region should be assessed. The term " capable fault" as used in Part 40, Appendix A, Criterion 4(e) has the same a
meaning as defined in Section III(g) of Appendix A to 10 CFR Part 100. Alternatively, the licensee .may choose to use the term " capable tectonic source" as defined in Appendix A to Regulatory Guide 1.165 (NRC,1997) to conduct its deterministic analysis. Capability should be determined by suitable methods, such as those outlined by Slemmons (1977). Fault length versus magnitude relationships developed by Slemmons (1982) or Bonilla (1984) are appropriate for determining the maximum magnitude earthouake that may be produced by each capable fault or cap. ble tectonic source. For each maximum magnitude earthquake, the PHA at the site should be determined using an accepted attenuation relationship between earthquake magnitude and distance. Campbell and Bozorgnia (1994) is an example of an acceptable relationship. In applying the relationship, the site-to-source distance should be the distance between the site and the closest approach of the fault. The PHA value adopted for each capable fault or tectonic sout:e should be no less than the median value provided by the attenuation relationship.
Possible soil amplification effectnros!d be considered.
} To assess potential site ground motion frcm earthquakes not associated with known tectonic structures (i.e., randorn or floating earthquakes), the largest floating earthquake reasonably expected within the tectonic prevince (no smaller than magnitude 6.2) should be identified. In addition, the largest floating earthquakes characteristic of any adjacent tectonic provinces should be identified, if such earthquakes may cause appreciable ground motion at the site. For each of these earthquakes, the PHA at the site should be calculated as stated above. However,15 km should be used as the site-to-source distance for floating earthquakes within the host tectonic province and in proximate provinces less than 15 km from the site. For floating earthquakes in tectonic provinces more than 15 km from the sit >, the distance
' between the site and the closest approach of the province boundary should be used u the site-to-source distance.
The PHA for the site should be the maximum value of the PHAs determined for earthquakes from all capable faults or tectonic sources and floating earthquakes.
Probabijjstic Analysis A PSHA yields a curve of er.ceedence probability versus PHA. An exceedence value no greater than 10d per year should be used in determining the PHA for the site. The 10" value represents a 1 in 10 chance of the site exceeding the PHA in a 1,000-year period, which is appropriate for a 1,000-year design life.
The seismic hazard analysis of uranium recovery mill sites by Bernreuter et al. (1994) contains probabilistic analyses that are acceptable for determining PHAs for the respective mill sites. The use of a PSHA as an alternative to the requirements of Part 40, Appendix A, Criterion 4(e), is acceptable, as steted in the introduction to Appendix A, provided that it can be shown that the desh,n proposed by the 1-9 NUREn-1620 r
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l licensee will achieve a level of stabilization and containtnent, and a level of protection for public health and safety and the environment, which is equivalent to, to the extent practicable, or more stringent than the achieved by the requirements of Part 40, Appendix A (See discussion in Chapter 2 of this SRP).
The licensee, when proposing alternatives, may take into account local or regional conditions, including geologic conditions. Altematives based on the seismic value proposed by the licensee must therefore, i
meet criteria laid out in Chapter 2 of this SRP.
The presentation on seismotectonic stability is acceptable if sufficient information is provided to support interpretations and conclusions. If the staff should conclude that the information provided is insufficient, '
it will request additional information or investigations. The staff determination of compliance shall be based, in part, on professionaljudgment, considering the complexity of site and seismic conditions.
1.4.4 Evaluation Findings If the staff's review as described in SRP Section 1.4 results in the acceptance of the characterization of the seismicity of the region and site, the following conclusions may be presented in the TER.
The NRC has completed its review of the information related to the characternation of the seismicity at I the facility. This revirw included an evrJuation using the review procedures in SRP Section 1.4.2 ud acceptance criteria outlined in SRP Section 1.4.3.
'Ibe licensee has acceptably described the regional and site-specific seismicity by providing adequate discussiens and interpretations of data and repons pertinent to the seismicity of the site and the associated region, and the potential for impacts to the site from seismic events. Information provided includes descriptions of historical canhquakes, locations of their epicenters, and an analysis of the seismic hazard at the site. The staff concludes that the information provided is suffL.hnt to suppon an analysis of the geotechnical stability and potential impacts to the surface and groc .ater conditions of the site. In addition, the staff concludes that the licensee has used acceptable methoa.s ofinvestigation and analysis to suppon its conclusions.
On the basis of the information and analysis provided in the application of the seismicity and seismic hazards at the facility, the NRC staff has concluded that the information is sufficient to support a determination that the following requirements of 10 CFR Pan 40, Appendix A or acceptable j altematives have been met:(1) Criterion 4(e), which requires that the impoundment not be located near a capable fault on which an MCE larger than that which the impoundment could be reasonably expected to ,
withstand might occur, or an acceptable alternative method of determination of the sites's seismic !
hazard, and (2) Criterion 6(1), which requires that the design of the disposal facility provide reasonable assurance of control of radiologicu hazards to be effective for 1,000 years, to the extent reasonably ,
achievable, and, in any case, for at least 200 years. If the PSHA is used as an alternative method of l I
determination of the seismic hazard, the licensee must provide sufficient infarmation to suppon an analysis of the facility design for the operational and closure periods. I i
1.4.5
References:
Bemreuter, D., E. McDermott, and J. Wagoner.1994. " Seismic hazard analysis of Title II reclamation l
plans." Lawrence Livermore National Laboratory,1994.
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Bonilla, M.G., R. K. Mark, and J. J. Lienkaemper,1984, " Statistical Relations among Eanhquake
! Magnitude, Surface Rupture Length, and Surface Fault Displacement," Bulletin of the Seismological Society of America, vol. 74, pp 2379-2411,1984.
Cami tell, K.W., and Y. Bozorgnia.1994. "Near source attenuation of peak horizontal acceleration from worldwide accelerograms recorded from 1975 to 1993." Fifth U.S. National Conference on Earthquake ;
Engineering, Chicago, IL, July 10-14,1994.
Nuclear Regulatory Commission,1997. " Identification and characterization of seismic sources and determination of safe shutdown canhquake ground motion." Regulatory Guide 1.165, March 1997, U.S.
Nuclear Regulatoiy Commission.
Slemmons, D.B.,1977. " State-of-the-Art for Assessing Earthquake Hazards in the United States: Report 6, Faults and Earthquake Magnitudes," Miscellaneous paper S-73-1, U.S. Army Engineer Waterways Experiment Station, Corps of Engineers, Vicksburg, Mississippi,1977.
Slemmons, D.B.,P.O'Malley, R.A. Whitney, D.H. Chung, and D.L. Bemreuter,1982, " Assessment of Active Faults for Maximum Credible Eanhquakes of the Southem California-Nonhern Baja Region,"
University of Califomia, Lawrence Livermore National Laboratory Publication No. UCID 19125,48 p, 1982.
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- 2,0 GEOTECHNICAL STABILITY i
! The RP and its supporting documents must contain geotechnical information, design details, and l construction considerations related to the proposed disposal site and all materials associated with the ~
l reclamation design, including soil and rock cover, foundation materials, contaminated materials, and l other materials, for any zones, such as liners, filters, or capillary breaks. SRP Chapter 2 establishes the l procedures for NRC staff to conduct and doc'iment the review of geotechnical stabili;y aspects of reclamation plans for mill tailings impoundments, amendments to the approved reclamation plans, or license termination.
I 2.1 SITE AND URANIUM MILL TAILINGS CHARACTERISTICS 2.1.1 Areas of Review The staff shall review infomution presented in the RP on the geotechnical aspects of the regional and site stratigraphy, the geotechnical characteristics of the uranium mill tailings and other materials designated for stabilization, and borrow am Mgraphy and material characteristics. "Other materials" include contaminated soil from site cleanup operations, tailings from other sites accepted for disposal at this site, and any contaminated materials from mill decommissioning activities to be disposed of at this site. This review shall include exploration data, sampling and laboratory techniques, test results, descriptions of physical properties, and static and dynamic geotechnical engineering parameters of the materials, as well as discussions of groundwater conditions (e.g., perched, confined, or unconfined) for all critical subsurface strata at the site, including information on the fluctuations of the hydraulic head.
Review of the groundwater information shall be coordinated with the review of groundwater resources protection information, as described in SRP Chapter 4. Review of stratigraphic and seismologic information shall be coordinated with the review of the geology and seismology information as described in SRP Chapter 1. Eorrow area restoration plans shall be evaluated.
2.1.2 Review Procedures I
l The information to be reviewed depends on whether the proposed tailings disposal is below ground in
- mines or excavated pits or in above ground impoundments. The reviewer should focus on the I appropriateness of the site characterization for the proposed tailings disposal scherne. The reviewer shall examine the site stratigraphy and evaluation of engineering properties of the underlying materials at the site, uranium mill tailings, other materials, and borrow materials to determine if appropriate methods were properly used in characterizing the materials.
The reviewer shall examine the following specific descriptive information to determine its adequacy for characterizing the site and for supporting the evaluations of reclamation system performance:
l (1) Site stratigraphy, based on borings and other investigations conducted to determine the type, location, <1 thickness of underlying materials; I (2) Regional and site-specific seismologic information to determine the potential for impact on the geotechnical stability of the site and site structures; 2-1 NUREG-1620 l
s (3) Stratigraphy specifying type, location, and thickness of borrow material and other materials designated for stabilization in the tailings disposal cell; (4) In situ testing programs and procedures conducted to determine the engineering properties of underlying materials at the site, borrow area material, other materials, and tailings; (5) Sampling programs conducted to obtain laboratory samples for determination of engineering propenies of borrow materials, underlying materials at the site, other materials, and tailings; (6) Laboratory testing used to determine the engineering propenies of borrow materials,
' underlying materials at the site, other materials, and tailings; (7) Physical and engineering properties of borrow materialt, underlying materials at the site, other materials, and tailings; and (8) Records of historical groundwater-level fluctuations at the site.
The reviewer shall evaluate methods used to characterize the site to ensure that they comply with generally accepted standards, such as, American Society for Testing and Materials (ASTM,1977) and are commonly used in the geotechnical engineering profession. Areas to be examined in this respect include the in situ and laboratory testing programs, sampling techniques, and analyses for determining the physical and engineering properties of materials at the site. Field investigations and laboratory testing procedures not commonly used in the geotechnical engineering profession will be reviewed in detail.
The staff's determination of compliance shall be based in part on professional judgment, considering the complexity of the site subsurface conditions.
7.1.3 Acceptance Criteria The site characterization information constitutes part of the input data needed for analysis and design of the tailings impoundment facility. The site characterization will be acceptable ifit provides the needed input for the design and analysis of the disposal facility r.nd meets the following criteria:
(1) The site stratigraphy is described in sufficient detail to provide an understanding of the site-specific subsurface features, including structural features and other characteristics of underlying soil and rock.
(2) Information on regional and local faults and seismicity, as obtained from field data, published literature, and historical records, is presented in sufficient detail to effectively incorporate that information into a geotechnical stability analyses. (Note: This aspect of the review is to be coordinated with the geology and seismology review performed under SRP Chapter 1.)
(3) Sampling scope and techniques ensure that samples are representative of the range of in situ soil conditions, taking into consideration variability and uncertainties in such conditions within the site.
NUREG-1620 2-2
(4) For all soils that might be unstable because of their physical or chemical properties, locations ,
and dimensions are identified and the properties have been documented. l (5) Investigations (including laboratory and field testing) are conclucted using appropriate standards published by the ASTM or the International Society for Rock Mechanics (ISRM) and are sufficient to establish the static and dynamic engineering parameters of borrow materials, other materials, tailings, and underlying soil and rock materials at the site (NRC, 1978,1979). j (6) A detailed discussion oflaboratory sampn preparation techniques is provided, when standard j procedures are not used. !
l l
For critical laboratory tests, details, such as how saturation of the sample was determined and j maintained during testing;, or how the pore pressures changed, are given. A detailed and quantitative discussion of the criteria used to verify that the samples were properly taken and tested in sufficient number to define the critical soil parameters for the site is provided. In the case of tailings material (for example license amendment reviews) the evaluations ofits strength and settlement parameters are presented in detail.
(7) Parameter values are presented to enable evaluation of properties of mill tailings, borrow I materials, other materials, and underlying soil and rock, including the following:
(a) Compressibility and rate of consolidation; (b) Shear strength including, for sensitive soils, possible loss of shear strength due to l strain-softening; (c) Liquefaction potential; (d) Permeability.
(e) Dispersion characteristics; (f) Swelling and shrinkage; (g) Long-term moisture content for radon barrier material; and (h) Cover cracking.
(8) Soil stratigraphy and relevant parameters that are used in the geotechnical evaluations (settlement, stability, liquefaction potential, etc.) are discussed in detail.
(9) Records of historical groundwater-level fluctuations at the site as obtained from nlonitoring local wells and springs and/or by analysis of piezometer and permeability data from tests conducted at the site are presented in sufficient detail to effectively incorporate the information 2-3 NUREG-1620 L_ .
4
.. y I
l into geotechnical stability analyses. (Note: This aspect of the revicw is to be coordinated with the hydrogeologic characterization review performed under SRP Chapter 4.).
The information should be sufficient to provide the required input for the design of the facility and to enable the reviewer to assess compliance with the regulatory requirements such as - site features contributing to waste isolation; preferred mode of disposal being below grade; facility not located near an active fault to mitigate the impact of an earthquake on the facility; and the design providing reasonable assurance of control of radiological hazards to be effective for 1,000 years to the extent reasonably achievable, and in any case for at least 200 years.
2.1.4 Evaluation Findings If the staff review as described in SRP Section 2.1 results in the acceptance of the characterization of the site and uranium mill tailings sufficient to support a conclusion regarding the geotechnical stability of the site, the following conclusions may be presented in the TER.
NRC has completed its review of the information concerned with the characterization of the site stratigraphy and uranium mill tailings at the facility. This review included an evaluation using the review procedures in SRP Section 2.1.2 and acceptance criteria outlined in SRP Section 2.1.3.
' The licensee has acceptably described the geotechnical characteristics of the site and uranium mill tailings based on sampling techniques that are accepable, and will ensure that a representative range of in situ soil conditions will be examined. Unstable soils have been identified. Investigations and analyses have used acceptable standards and practices. Laboratory sample preparation ar.d testing techniques are appropriately described and include: (1) compressibility arid rate of consolidation; (2) shear strength; (3) liquefaction potential; (4) permeability; (3) dispersion characteristics; (6) swelling and shrinkage; and (7) physical properties. Records of historic groundwater-level fluctuations are presented to allow effective incorporation into geotechnical stability analyses.
On the basis of the information provided in the application, and detailed review of the characte istics of the site and uranium mill tailings at the facility, the staff has concluded that the characterization of the site and uranium mill tailings and associated conceptual and numerical models provide an acceptable input, which along with other information such as results of design analysis etc., will enable the staff to make a finding on the demonstration of compliance with the following criteria in Appendix A to 10 CFR Part 40: (1) Criteria 1, which relate to the site features that contribute to the permanent waste isolation characteristics of the site; (2) Criterion 3, which discusses the primary option for disposal of tailings below grade is mines or excavated pits (if applicable for the site); (3) Criterion 4(e), which requires that which the impoundment not be located near a capable fault on which an MCE larger than that which the impoundment could reasonably be expected to withstand might occur; (4) Criterion 5(G)(2), relating to the permeability characteristics of the site, and (5) Criterion 6(1), relating to providing reasonable assurance of control of radiological hazards to be effective for 1,000 years to the extent reasonably achievable, and in any case for at least 200 years.
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2.1.5 References American Society for Testing and Materials (ASTM),1997, Annual Book ofASTM Standards, Section 4,
" Construction," Volume 0408: Soil and Rock: Dimension of Stone; Geosynthetics, Philadelphia, PA: American Society for Testing and Materials.
Nuclear Regulatory Commission,1978. " Laboratory Investi;.itions of Soilt for Engineering Analysis ar d Design of Nuclear Power Plants," Regulatory Guide 1.138, April 1978.
Nuclear Regulatory Commission,1979. " Site Investigations for Foundations of Nuclear Power Plants,"
Regulatory Guide 1.132, Revision 1, March,1979.
2.2 SLOPE STABILITY 2.2.1 Areas of Review The staff shall examine exploration data, test results, slope characterization data, design details, and static and dynamic analyses related to the stability of all natural and man-made canh and rock slopes whose failure, under any of the conditions to which they could be exposed throughout the period of regulatory interest, could adversely affect the integrity of the reclamation actions.This review shall also include examination of static and dynamic materials properties, test and design methods, pore pressures within and beneath the embankment, and the design seismic coefficient. Information on the design seismic event should be obtained from resula of the review completed using SRP Chapter 1. The review will focus on (1) the design of the impoundment during operation when a large volume of tailings liquor would be present and (2) its stability over bng-term.
2.2.2 Review Procedures The reviewer shall examine data resulting from site investigations such as borings; maps; laboratory and
, field test results; soil profiles; site plans; results of seismic investigations; permeability test results; and l static, dynamic, or pseudostatic stability analyses to determine whether the assumptions and analyses used in the reclamation plan (RP) are conservative. The degree of conservatism required depends on the type of analysis used, the variability and uncertainty in the values of the parameters considered in the slope stability analysis, the number of borings, the sampling program, the extent of the laboratory testing program, and the resultant safety factor. For instances where safety factors are low, the reviewer shall ensure that reasonable ranges of soil preperties have been considered. Other factors, such as flood conditions, pore pressure effects, possible erosion of soils, and seismic amplification effects, shall be conservatively assessed. The design criteria and analyses shall be reviewed to ascertain that the techniques employed are appropriate and represent commonly accepted methods (e.g., Army Corps of Engineers,1970b).
The reviewer shall examine the spatial variability of the mehsured properties to ensure that it has been adequately defined. The reviewer shall also examine slope characterization data to ensure that nearby 2-5 NUREG-1620
slopes, the failure of which could adversely affect the stability of the reclamation action, have been properly characterized.
1 The reviewer shall determine whether the static and dynamic stability analyses demonstrate that there is j an adequate factor of safety against failure.
The reviewer shall examine the slope stability analysis to determine that an appropriately conservative approach has been used and that adverse conditions to which the slope might be subjected have been considered. The reviewer shall confirm that the static analyses include calculations using appropriate assumptions and methods to assess the following:
(1) Uncertainties and variations in the shape of the slope, the boundaries and parameters of the several types of soils within the slope, the forces acting on the slope, and the pore pressures acting within and beneath the slope; (2) The failure surface corresponding to the lowest factor of safety; and (3) The effect of the assumptions inherent in the method of analysis used.
The reviewer shall ensure that the analysis is conservative and that possible failure modes have been considered, including evaluation of the effect of the MCE, or the appropriate design criteria found acceptable in SRP Chapter 1.4.
The reviewer shall be aware that no single method of analysis is applicable for all stability assessments.
Therefore, no single method of analysis is recommended. If the staff review indicates that questionable assumptions have been made or that nonstandard or inappropriate methods of analysis have been used, the staff may model the slope in a manner consistent with the data and perform an independent analysis.
The reviewer shall verify that disposal cell slopes will be relatively flat, after final stabilization, to minimize the potential for erosion and to provide a conservative factor of safety. In evaluating the slope, the reviewer will focus on determining if the slopes are 5h:1y as required by Past 40, Appendix A, Criterion 4(c). If slopes steeper than Sh:1y are proposed, the reviewer must evaluate these steeper slopes as an alternative to the requirements of Criterion 4(c). In conducting a review of steeper slopes, the reviewer must evaluate the acceptability of the steeper slope using the applicable criteria in this SRP as well as determine if there is an acceptable economic basis and an equivalent level of protection available to justify an alternative to Part 40, Appendix A, Criterion 4(c). The reviewer shall verify that a properly designed, fully self-sustaining vegetative cover can be placed over the tailings pile, primarily to reduce the wind and water erosion to negligible levels. If a vegetative cover is not suitable for the site conditions, the reviewer shall verify that an appropriate rock cover has been provided. This verification shall be coordinated with the review of SRP Chapter 3.
Dams at operating facilities or that continue to hold water after the cessation of opemtion are also subject to the National Dam Safety Program Act of 1996. As such, the reviewer will need to determine if the dam is classified as a low hazard potential or high hazard potential stmeture. If the dam is classified as high hazard, the reviewer will also need to evt'uate the Emergency Action Plan (EAP).
NUREG-1620 2-6
2.2.3 Acceptance Criteria The analysis of slope stability will be acceptable if it meets the following criteria:
(1) Slope characteristics are properly evaluated.
(a) Cross-sections and profiles of natural and cut slopes whose instability would directly or indirectly affect the control of residual radioactive materials are presented in sufficient number and detail to enable selection of the cross sections for detailed stability evaluation.
(b) Slope steepness is a minimum of five horizontal (Sh) to one vertical (lv) or less. The use of slopes steeper than Sh:lv is considered an alternative to the requirements in Part 40, Appendix A, Criterion 4(c). When slopes steeper than Sh:lv are proposed, a l I
technicaljustification as to why a Sh:lv or flatter slope cannot be constructed is provided. Appropriate compensating factors and conditions are incorporated in the slope design for assuring long-term stability. In addition, the application must contain an evaluation showing the economic benefit of slopes steeper than 5h:lv as well as a 1 demonstration of equivalent protection. l (c) Locations selected for slope stability analysis are determined considering the location of maximum slope angle, slope height, weak foundation, piezometric level (s), the extent of rock mass fracturing (for an excavated slope in rock), and the potential for local erosion.
I (2) An appropriate design static analysis is presented.
1
- For static loads, the static analysis includes calculations with appropriate assumptions and methods of l analysis (NRC,1977) and considers the following factors
l i (a) The uncertainties and variability in the shape of the slope, the boundaries and parameters of the several types of soils and rocks within the slope, the material properties of soil and rock within and beneath the slope, the forces acting on the slope, and the pore pressures acting within and beneath the slope; l
(b) Appropriate failure modes during and after construction and the failure surface 1 l corresponding to the lowest factor of safety. (The analysis takes into account the failure j surfaces within the slopes, including any possible through the foundation.);
(c) 'Ihe effect of the assumptions inherent in the method of analysis; (d) Adverse conditions such as high water levels from severe rain and the probable maximum flood; i
(e) The effects of toe erosion, incision at the base of the slope, and other deleterious effects of surface runoff;and j l
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(f) Minimum acceptable values of safety factors for slope stability analysis given in NRC l (1977).
(3) Appropriate dynamic and pseudostatic analyses are presented to include the following considerations:
.(a) For dynamic loads, the dynamic or pseudostatic analysis includes calculations with appropriate assumptions and methods (NRC,1977; Seed,1%7; Lowe,1%7; Department of the Navy,1982a,b,c; Army Corps of Engineers,1970a,b,1971,1972; Bureau of Reclamation,1%8).
(b) Pseudostatic analysis is acceptable in lieu of dynamic analysis if the strength parameters used in the analysis are conservative, the materials are not subject to significant loss of strength and development cf high pore pressures under dynamic loads, the design seismic coefficient is 0.20 or less, and the resulting minimum factor of safety suggests an adequate margin, as provided in NRC(1977).
./
The reviewer shall also determine, for pseudostatic analysis of slopes subjected to earthquake loads, that an assumption is made that the earthquake imparts an additional horizontal force acting in the direction of the potential failure (Army Corps of Engineers, 1970b,1977; Goodman,1989). The critical failure urface obtained in the static analysis is used in this analysis with the added driving force. Minimum acceptable values for safety factors of slope stability analysis are given in Regulatory Guide 3.11 (NRC, 1977).
(c) An appropriate analysis method has been used. A number of different methods of analysis are available (e.g., slip circle method, method of slices, and wedge analysis) with several variants of each (Lambe and Whitman,1979; Army Corps of Engineers, 1970b; NRC,1977; Bromhead,1992). Limit-equhibrium analysis methods do not provide information regarding the variation of strain within the slope and along the slip surface. Consequently, there is no assurance that the peak strength values used in the I
analysis can be mobilized simultaneously along the entire slip surface unless the material shows ductile behavior (Duncan,1992). Residual strength values should be evaluated if mobilized shear strength at some points is less than the peak strength. The reviewer should ensure that appropriate conservativeness has been incorporated in the analysis using the limit equilibrium methods. The limit equilibrium analysis methodologies may be substituted with other techniques, such as finite element or finite difference methods.
If any important interaction effects cannot be included in an analysis, the reviewer must determine that such effects have been treated in an approximate but conservative fashion. The engineering judgment of the reviewer must be used in assessing the adequacy of the resulting safety factors (NRC,1983a,b).
(d) The assessment of the dynamic stability considers the MCE and the potential site amplification of ground motions. The dynamic analysis has accounted for the effect of NUREG-1620 2-8
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l dynamic stresses of the MCE on soil strength parameters. The potential for liquefaction
]
of the soil shall be reviewed using the procedure in SRP Section 2.4. As in a static q analysis, the parameters such as geometry, soil strength, and hydrodynamic and pore pressure forces are varied in the analysis to show that there is an adequate margin of safety.
(e) The reclamation plan may include an optional dynamic analysis, following the procedures suggested by Newmark (1965), Seed and Bonapane (1992), and others, to show that the possible permanent deformation sustained in the slope from the MCE will not damage the disposal cell to such at extent that the effectiveness of the disposal cell is significantly reduced. The reviewer should verify that the yield acceleration or pseudostatic horizontal yield coefficient necessary to reduce the factor of safety against slippage of a potential sliding mass to 1.0 in a "Newmark-type" analysis has been adequately estimated (Seed and Bonaparte,1992).
(f) Seismically induced displacement is calculated and documented. There is no universally accepted magnitude of seismically induced displacement for determining acceptable performance of the disposal cell (Seed and Bonaparte,1992; Goodman and Seed,1966). ;
Surveys of five major geotechnical consulting firms by Seed and Bonapane (1992) l indicate that the acceptable displacement is from 15 to 30 cm. (6 to 12 in.) for tailings l piles. The reviewer shall ensure that this criterion is also augmented by provisions for periodic maintenance of the slope (s).
(g) The following additional items are included in the analyses.
(i) Selection of the appropriate design level seismic events and/or strong ground motion accelerations; (ii) Evaluation of the influence oflocal site conditions on the ground motions j associated with a design level event; j t
(iii) Evaluation of the dynamic response of the waste fill (tailings), j embankments, and foundation system, especially the effect of cyclic motion of an earthquake on soil strength propenies, to verify the potential for liquefaction. Where there is potential for liquefaction, changes in pore i I
pressure from cyclic loading are considered in the analysis to assess not only the potential for liquefaction but also the effect of pore pressure increase on the stress-strain characteristics of the soil and the post- !
eanhquake stability of the slopes. Evaluations of dynamic properties and !
shear strengths for the tailings, underlying foundation material, radon l barrier cover, and base liner system are based on representative materials l propenies obtained through appropriate field and laboratory tests (NRC, ;
1978,1979); and . j 2-9 NUREG-1620 J
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(iv) Evaluation of overall seismic stability, using pseudostatic analysis, with appropriate design seismic coefficient, or dynamic analysis, as appropriate (Army Corps of Engineers,1977; NRC,1977). The design seismic coefficient to be used in the pseudostatic analysis is either 67 percent of the peak acceleration of the MCE at the foundation level of the tailings pile or 0.10, whichever is greater. Altematively, a dynamic analysis following Newmark (1%5) can be carried out to establish that the permanent deformation of the disposal cell from the MCE will not be detrimental to the disposal cell. If the design seismic coefficient is greater than 0.20, then the dynamic stability investigation (Newmark,1965) should be augmented by other appropriate methods (i.e., finite element method), depending on specific site conditions.
(4) Provision is made to establish a vegetative cover, or other erosion prevention, to include the following considerations:
(a) The vegetative cover and its primary functions are described in detail.
This detennination shall be made with respect to any effect the vegetative cover may have on mducing slope erosion and should be coordinated with the reviewer of SRP Chapter 3.
If strength enhancement from the vegetative cover is taken into account, the methodology should be appropriate (Wu,1984).
(b) In arid and semi-arid regions, where a vegetative cover is deemed not self-sustaining, a rock cover is employed on slopes or the mill tailings. If credit is taken for strength enhancement from rock cover, the reviewer should confirm that appropriate methodology has been presented.
The design of a rock cover, where a self-sustaining vegetative cover is not practical, is based on standard engineering practice. SRP Chapter 3 discusses this item in detail.
(5) The dam meets the requirements of the dam safety program if the application demonstrates that:
- (a) The dam is correctly categorized as low hazard potential or high hazard potential structure using the definition of the U.S. Federal Emergency Management Agency (FEMA); and (b)If the dam is ranked as a high hazard potential, an acceptable EAP consistent with the U.S.
Federal Emergency Management Agency guide (FEMA,1998) has been developed.
(6) The use of steeper slopes as an alternative to the requirements in Part 40, Appendix A, will be found acceptable if the following are met:
i NUREG-1620 2-10 I
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'.' l (a) Achieve a equivalent level of stabilization and containment of the site concemed and protection of public health, safety, and environment; and (b) Demonstrate a site specific need for the alternate slopes and an economic benefit.
2.2.4 Evaluation Findings If the staff s review as described in SRP Section 2.2 results in the acceptance of the slope stability, the following conclusions may be presented in the TER.
NRC has completed its review of the information concerned with the slope stability at the facility.
This review included an evaluation using the review procedures in SRP Section 2.2.2 and acceptance criteria outlined in SRP Section 2.2.3.
The licensee has acceptably described the slope stability evaluation by: (1) providing cross-sections and profiles of natural and cut slopes in sufficient detail and number to represent significant slope and
- foundation conditions;(2) placing tailings below grade or in demonstrably safe above grade disposal i facilities; (3) ensuring that slope steep nesses are five horizontal to one venical or less or providing technicaljustification for a different slope ratio; (4) providing measurements of static and dynamic propenies of soil and rock using standards such as those established by the ASTM, ISRM, NRC, or U.S.
Army Corps of Engineers; (5) selecting locations for slope stability analyses while considering the location of maximum slope angle, slope height, weak foundation, the extent of rock mass fracturing, and the potential for local erosion; and (6) describing vegetative cover and its primary functions in detail. In
- cases where the licensee has proposed use of steeper slopes as an alternative to the requirements of Pan l 40, Appendix A, Criterion 4(c), the staff has evaluated the licensee's demonstration that steeper slopes would result in economic savings and also ensure the long-term stabilization of the tailings with a level of protection equivalent to that required in Part 40, Appendix A, Criterion 4(c). Therefore, the use of L
steeper slopes meets the alternatives requirement in Fut 40, Appendix A.
The static loads analysis is acceptable and includes (1) appropriate uncertainties and variabilities in imponant rock / soils parameters:(2) consideration of appropriate failure modes; (3) a discussion of the effect of the assumptions inherent in the method of analysis used; (4) consideration of adverse conditions, including flooding, with appropriate safety factors; and (5) the effects of toe erosion, incision of the base of the slope, and other deleterious effects of surface runoff.
The dynamic and pseudostatic analyses are acceptable and include: (1) calculations with appropriate assumptions and methods; (2) treatment of important interaction effects in a conservative fashion; (3) an accounting of the dynamic stresses of the MCE on soil strength parameters;(4) for pseudostatic analyses of slopes subjected to canhquake loads, consideration of the added driving horizontal force acting in the direction of a potential failure; (5) determination that possible permanent deformation sustained in the slope from MCE will not damage the effectiveness of the disposal cell; (6) determination that the magnitude of seismically induced displacement does not exceed 15 to 30 cm. (6 to 12 in.); (7) a selection of appropriate design level seismic events or strong ground motion accelerations; (8) evaluations of local site conditions; (9) evaluations of the potent! ' for liquefaction and the effect of pore pressure increase on the stress-strain characteristics of the soil and post earthquake stability of the 2-11 NUREG-1620 1
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slopes;(10) evaluations of the dynamic propedies and shear strength of the tailings, underlying foundation, radon barrier cover, and base liner system; and (11) design of a self-sustaining vegetative or rock cover that is consistent with commonly accepted engineering practice.
On the basis of the information provided in the application and the detailed review conducted of the slope stability at the facility, the staff has concluded that the slope stability and associated conceptual and numerical models pertaining to design in the RP provide an acceptable input to demonstration of compliance with 10 CFR Part 40, Appendix A: (1) Criterion 4(c), which provides requirements for the long-term stability of the embankment and cover slopes for tailings;(2)
Criterion 4(d), which requires establishment of a self-sustaining vegetative cover or employment of a rock cover to reduce wind and water erosion to negligible levels, that individual rock fragments are suited for the job, and that the impoundment surfaces are contoured to avoid concentrated surface runoff or abrupt changes in slope gradient; (3) Criterion 4(e), which requires that the impoundment not be located near a capwle fault on which an MCE larger than that which the impoundment could reasonably be expected to withstand might occur; (4) Criterion 5(A)(5), which requires the structural integrity of slopes (dikes) to prevent massive failure of the dikes; and (5) Criterion 6(1), relating to provicPng reasonable assurance of control of radiological hazards to be effective for 1,000 years to the extent reasonably achievable, and in any case for at least 200 years.
2.2.5 References Army Corps of Engineers,1970a. Laboratory Soil Testing, Engineering Manue! EMI110-2-1906.
November 1970.
At ny Corps of Engineers,1970b. Engineering and Design Stability ofEarth and Rock Fill Dams.
Engineering Manual EMI110-2-1902. Office of the Chief of Engineers, Department of the Army 1970.
Army Corps of Engineers,1971. Instrumentation ofEanh and RocifillDams, Engineering Manual EMI110-2-1908, Part I and 2, August and November 1971.
Army Corps of Engineers,1972. Soil Sampling, Engineering Manual EMI110-2-1907, March 1972.
Army Corps of Engineers,1977. Ec pa Design and Analysisfor Corps ofEr ineer Dams, ERI110-2-1806, April 197 Bromhead, E.N.,1992. The Stability of Slopes, United Kingdom, London: Blacki' Academic &
Professional,1992.
Bureau of Reclamation,1968. Earth Manual, First Edition, Washington, DC: U.S. Department of the Interior,1968.
Department of the Navy,1982a. SoilMechanics, NAVFAC DM 7.1, May 1982.
Department of the Navy,1982b. Fourdations and Earth Structures. NAVFAC DM 7.2, May 1982.
NUREG-1620 2-12
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Department of the Navy,1982c. Soil Dynamics, Deep Stabilization, and Special Geotechnical I Construction, NAVFAC DM 7.3, May 1982.
Duncar., J.M.,1992, State-of-the-Art: Static Stability and Deformation Analysis. Stability and Performance of Slopes and Embankments-II, Volume 1. Proceedings ofa specialty conference. R.B. Seed. and R.W. Boulanger, eds. Geotechnical Special Publication No. 31.
New York, NY: American Society of Civil Engineers,1992.
Goodman, R.E,1989, Introduction to Rock Mechanics, 2nd edition, New York, NY: John Wiley & Sons, 1989.
Goodman, R.E., and H.B. Seed,1966. " Earthquake-Induced Displacements in Sand Embankments,"
ASCE Journal of the Soil Mechanics and Found.itions Division 92(SM2): March 1966.
Lambe, T.W., and R.V. Whitman,1979, SoilMechanics, SI Version, New York, NY: John Wiley &
Sons,1979.
Lowe, J., III.,1967, " Stability Analysis of Embankments," ASCE Journal ofthe Soil Mechanics and Foundations Division, 93(SM4) 1967.
Newmark, N.M.,1%5, " Effects of Earthquakes on Dams and Embankments," Geotechnique, June 1965.
Nuclear Regulatory Commission,1977, " Design, Construction. and Inspection of Embankment Retention Systems for Uranium Mills," Regulatory Guide 3.11, Revision 2, December 1977.
Nuclear Regulatory Commission,1978, " Laboratory Investigations of Soils for Engineering Analysis and Design of Nuclear Power Plants," Regulatory Guide 1.138, April 1978.
Nuclear Regulatory Commission,1979, " Site Investigations for Foundations of Nuclear Power Plants,"
Regulatory Guide 1.132, Revision 1, March 1979.
Nuclear Regulatory Commission,1983a, Guidancefor Disposal of Uranium Mill Tailings: Long-Term Stabilization ofEanhen CoverMaterials, NUREGICR-3199.
Nuclear Regulatory Commission,1983b, Design Considerationsfor Long-Term Stabilization of Uranium Mill Tailings impoundments, NUREGICR-3397.
Seed, H.B.,1%7, " Slope Stability During Earthquakes," ASCE Journal of the Soil Mechanics and Foundations Division, 93(SM' i',67.
Seed R.B., and R. Bonaparte,1992, " Seismic A nalysis and Design of Lined Waste Fills: Current Practice. Stability and Performance of Slopes and Embankments-II," Volume 1, Proceedings ofa specialty conference, R.B. Seed, and R. W. Boulanger, eds, Geotechnical Special Publication No. 31. New York, NY: American Society of Civil Engineers,1992.
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I Wu, T.H.,1984, Effect of Vegetation on Slope Stability, " Soil Reinforcement and Moisture Effects on Slope Stability," Transportation Research Record 965, Transportation Research Board, National Research Council,1984.
)
I 23 SETTLEMENT 23.1 Areas of Review The staff shall review the methods and results of testing and analyses conducted to estimate deformation of subsurface materials and uranium mill tailings. This shall include examination of material properties and thicknesses of compressible materials, factors used in stress calculations, calculated pore pressures within and beneath the embankment, resulting total and differential settlement of the tailings surface under both static and seismic conditions, and the effects of such settlements on the radon barrier layer of the cover of the disposal cell and erosion protection layer. Liquefaction and associated settlement are addressed in SRP Section 2.4. One of the purposes of this review is to determine if the licensee has a an acceptable method for determining if tailings consolidation is sufficient to allow placement of radon barrier.
23.2 Review Procedures The reviewer shall examine the assessments of the magnitudes and distributions of settlement of the disposal cell and the analyses of the potential for cracking of the radon barrier from tensile strains in order to determine the adequacy of the design.
The reviewer shall confirm that clay layers and slime in the tailings pile and foundations have been considered in the assessment of both immediate and long-term settlement.
In reviewing the assessment of settlements, the reviewer shall give particular attention to the identification and thicknesses of compressible soil layers within the tailings and in the foundation.
Settlement should be calculated at several locations within the disposal cell to enable a determination of the overall settlement pattem of the disposal cell cover. The locations for settlement calculations should be selected considering the presence of sand / slime tailings and foundation materials. The tailings are expected to be a hydraulically placed material comprised ofinterspersed sand and slime tailings. The following specific items shall be reviewed to determine the acceptability of the assessment of the magnitudes and distribution of settlement.
(1) The analysis ofimmediate settlement of tailings surfaces, considering rebound from excavation and settlement from instantaneous compression of underlying materials and the tailings pile.
The computation ofincremental tailings loading and the width of the loaded area, as well as the determina't ion of the undrained modulus and Poisson's ratio shall be examined. Calculations of the settlement of hydraulically placed tailings shall be examined.
NUREG-1620 2-14
i s
(2) The analysis of consolidation settlement from delayed compression (caused by pore-pressure dissipation) of underlying materials and the taihngs pile.
The calculation of settlement shall be reviewed to ensure that each compressible soil layer witnin or undemeath the tailings pile is considered and is assigned proper thickness and that the appropriate level of stress change is applied at the mid-depth of the soil layer.
(3) The estimate of the time at which the primary consolidation settlement of the tailings will be essentially complete shall be verified. Generally, the radon barrier and disposal cell cover may be placed only after the settlement of tailings is essentially complete.
(4) The analysis of secondary settlement from long-term creep.
(5) The distribution of settlement magnitudes for assessment of differential settlement.
(6) Evaluation of the potential for cracking of the radon barrier layer as result of long-term settlement of the cover.
233 Acceptance Criteria The analysis of tailings settlement will be acceptable ifit meets the following criteria:
(1) Computation of immediate settlement follows the procedure recommended in NAVFAC DM-7.1 (Department of the Navy,1982). If an altemative procedure is used, the basis for such procedure is adequately explained.
The procedure recommended in NAVFAC DM-7.1 (Department of the Navy,1982) for calculation of immediate settlement is adequate if applied incrementally to account for different stages of tailings emplacement. If this method is applied, the reviewer shall verify that the computation of incremental tailings loading and the width of the loaded area, as well as the determination of the undrained modulus and Poisson's ratio, have been computed and documented.
Settlement of tailings arises from compression of soillayers within the disposal cell and in the underlying materials. Because compression of sands occurs rapidly, compression of sand layers in the disposal cell and foundations must be considered in the assessment ofimmediate settlement. However, the contribution ofimmediate settlement to consolidation settlement cannot be ignored. Clay layers and slime undergo instantaneous clastic compression controlled by their undrained stiffness as well as long-term inelastic compression controlled by the processes of consolidation and creep (Nuclear Regulatory Commission,1983a).
2-15 NUREG-1620
/
8 (2) Each of the following is appropriately considered in calculating stress increments for assessment of consolidation settlement:
(a) Decrease in overburden pressure from excavation; (b) Increase in overburden pressure from tailings emplacement; (c) Excess pore-pressure generated within the disposal cell; (d) Changes in groundwater levels from dewatering of the tailings; and (e) Any change in groundwater levels from the reclamation action.
(3) Material properties and thicknesses of compressible soil layers used in stress change and volume change calculations for assessment of consolidation settlement are representative of ]
in situ conditions at the site.
- 4) Material propenies and thicknesses of embankment zones used in stress change and volume ;
i change calculations are consistent with as-built conditions of the disposal cell.
(5) Values of pore pressure within and beneath the disposal cell used in settlement analyses are consistent with initial and postconstruction hydrologic conditions at the site.
(6) Methods used for settlement analyses are appropriate for the disposal cell and soil conditions at the site. Contributions to settlement by drainage of mill tailings and by consolidation / compression of slimes and sands are considered. Both instantaneous and time-dependent components of total and differential settlements are appropriately considered in the analyses (NRC,1983a, b, c).
The procedure recommended in NAVFAC DM-7.1 (Depanment of the Navy,1982) for calculation of secondary compression is adequate.
(7) The disposal cell is divided into appropriate zones depending on the field conditions for assessment of differential settlement, and appropriate settlement magnitudes are calculated and assigned to each zone.
(8) Results of settlement analyses are propenly documented and are related to assessment of overall behavior of the reclaimed pile.
(9) An adequate analysis of the potential for development of cracks in the radon / infiltration barrier as a result of differential settlements is provided (Lee and Shen,1969).
NUREG-1620 2-16
23,4 Evaluation Findings If the staff's review, as described in SRP Section 2.3 shows that the settlement has no impact on the integrity and functionality of the radon barrier and disposal cell cover, then the following conclusions can be presented in the TER. If the settlement impacts the cell cover integrity, then the licensee will be required to revise the design to ensure the functionality of the cell cover before a TER can be prepared.
NRC has completed its review of the information concemed with the characterization of settlement at the facility. This review included an evaluation using the review procedures in SRP Section 2.3.2 and acceptance criteria outlined in SRP Section 2.3.3.
'Ihe licensee has acceptably described settlement by providing computations following the procedure recommended in NAVFAC DM-7.1 (Department of the Navy,1982) or by explaining the technical merit for an attemative procedure. Material properties, thickness, and load increments used to calculate settlement are representative of site conditions.The applicant has acceptably considered each of the following: (1) decrease in overburden pressure from excavation; (2) increase in overburden pressure from emplaced tailing; (3) excess pore-pressure generated within the tailings disposal cell; (4) changes in groundwater levels from dewatering of the tailings; and (5) changes in groundwater levels from reclamation actions. Pore pressures within and beneath the disposal cell / embankment are consistent with initial and as-built hydrologic site conditions. Methods used to determine settlement are appropriate for the tailings embankment and soil conditions at the site. The results of the settlement analyses are properly documented. Acceptable subdivision of the tailings embankment into assesst wnt zones with
.yympiiately assigned settlement magnitudes has been accomplished. The settlement data would provide information to assess the possibility of surface ponding or sudden change of gradient caused by settlement. An acceptable analysis for the development of cracks in the radon / infiltration barrier is, provided.
On the basis ofinformation provided in the application, and the detailed review conducted of the settlement characteristics at the faciHty, the staff has concluded that the settlement and associated conceptual and numerical models provide input needed to demonstrate compliance with 10 CFR Part 40 Appendix A: (1) Criterion 4(d), which requires establishment of a self-sustaining vegetative cover or employment of a rock cover to reduce wind and water erosion to negligible levels, that individual rock fragments are suited for the job, and that the impoundment surfaces are contoured to avoid concentrated surface runoff or abrupt changes in slope gradient; and (2) Criterion 6(1), relating to providing reasonable assurance of contml of radiological hazards to be effective for 1,000 years to the
. extent reasonably achievable, and in any case for at least 200 years.
23.5 References Department of the Navy,1982. SoilMechanics, NAVFAC DM 7.1, May 1982.
Lee, K. L., and Shen, C.K.,1969, " Horizontal Movements Related to Subsidence," ASCE Journal ofSoil Mechanics and Foundations Division, 95(SM1),1%9.
Nuclear Regulatory Commission,1983a. "Consolidarion of Tailings," NUREG/CR-3204.
2-17 NUREG-1620 i
Nuclear Regulatory Commission,1983b. "Guidancefor Disposal of Uranium Mill Tailings: Long-Term Stabili:ation ofEarthen CoverMaterials," NUREGICR-3199.
Nuclear Regulatory Commission,1983c. " Design Considerationsfor Long-Term Stabilization of Uranium Mill Tailings Impoundments," NUREGICR-3397.
2.4 LIQUEFACTION POTENTIAL 2.4.1 Areas of Review The staff shall review the analysis of the liquefaction potential of subsurface, pile, and embankment materials, and the associated test and data interpretations. Consequences of the liquefaction of subsurface soils and/or uranium mill tailings affecting the settlements within and stability of the disposal cell and the erosion protection layer shall also be reviewed. Design features or mitigation actions that address liquefaction potential shall be examined. The effect of settlements not induced by liquefaction is considered in SRP Section 2.3 and is also included in SRP Section 2.4.3.
2.4.2 Review Procedt:res The reviewer shall examine the analysis of liquefaction potential by studying the results of geotechnical investigations and in situ tests such as standard penetration, piezocone, density, and strength tests as well as boring logs, laboratory classification test data, water table, perched water zones, and soil profiles, to determine if any of the site soils or the tailings pile material could be susceptible to liquefaction.
Ifit is determined that there may be liquefaction-susceptible soils beneath the site or in the tailings pile, ,
the reviewer shall examine the site exploration methods, laboratory test program, and analyses for l adequacy. Where global liquefaction potential exists, the reviewer shall determine that it has been mitigated or eliminated. Minor or local liquefaction potential shall have been accounted for in settlement analyses. ,
The reviewer shall compare the liquefaction potential analysis the RP to an independent study performed by me staff,if necessary.
2.4.3 Acceptance Criteria The analysis of the liquefaction potential will be acceptable if the following criteria are met:
(1) Applicable laboratory and/or field tests are properly conducted (NRC,1978,1979; Army Corps of Engineers, 1970,1972).
(2) Methods used for interpretation of test data and assessment of liquefaction potential are consistent with current pmetice in the geotechnical engineering profession (Seed and Idriss, 1971,1982). An assessment of the potential adverse effects that complete or pasi liquefaction could have on the stability of the embankment may be based on cyclic triaxial test NUREG-1620 2-18 c . _ - _ _ _ - - -
o ;
': o data obtained from undicirbed soil samples taken from the critical zones in the site area (Seed j and Harder,1990; Shannon & Wilson,Inc., and Agbabian-Jacobsen Associates,1972).
.(3) If global liquefaction poten,tial is identified, mitigation measures or redesign of tailings ponds / embankments is proposed and the proposed measure provides reasonable assurance that the liquefaction potential has been eliminated or :nitigated.
(4) If minor liquefaction potential is identified and is evaluated to have only a localized affect that l - may not directly affect the stability of embankments, the effect ofliquefaction is adequately
' accounted for in analyses of both differential and total settlement and is shown not to compromise the intended performance of the radon barrier. Additionally, the disposal cell is shown to be capable of withstanding the liquefaction potential associated with the expected
' maximum ground acceleration from earthquakes. The licensee may use post-earthquake stability methods based on residual strengths and deformation analysis to examine the effects l- of liquefaction potential. Furthermore, the effect of potential localized lateral displacement l from liquefaction, if any, is adequately analyzed with respect to slope stability and disposal cell integrity.
l 2.4.4 Evaluation Findings If the staff's review, as' described in SRP Section 2.4, results in the acceptance of the licensee's l liquefaction potential analysis, and conclusions on the impact on the performance of the disposal cell, the following conclusions may be presented in the TER.
NRC has completed its review of the information concerned with the evaluation and remediation (if needed) of liquefaction potential at the facility. This review included an evaluation using the review procedures in SRP Section 2.4.2 and acceptance criteria outlined in SRP Section 2.4.3.
. The licensee has acceptably evaluated liquefaction potential based on results from properly conducted !
laboratory and/or field tests. The methods used for interpretation of test data are consistent with current l l practice. Where global liquefaction is identified, mitigation measures or redesign of tailings l l ponds / embankments is proposed and the new design provides reasonable assurance that the liquefaction potential has been eliminated or mitigated. In the case of minor / local liquefaction potential, its effect is accounted for in the analysis of both differential and total settlement and is shown not to compromise the intended performance of the radon barrier and erosion protection. Large settlement will change the profile of the erosion protection cover and may promote formation of gullies etc.
On the basis of the information provided by tne licensee on the liquefaction potential at the j facility, the staff has concluded that the results of evaluation of liquefaction potential !
I
- and associated conceptual and numerical models provide input to a demonstration of compliance with 10 CFR Part 40, Appendix A
- (1) Criterion 4(c), which provides long-term stability requirements for the slopes of the tailings embankment and cover: (2) Criterion 4(d), which requires establishment of a self- !
L sustaining vegetative cover or employment of a rock cover to reduce wind and water erosion to l negligible levels, that individual rock fragments are suited for the job, and that the impoundment surfaces i are contoured to avoid concentrated surface mnoff or abrupt changes in slope gradient; and (3) Criterion 2-19 NUREG-1620 l
i ,'
6(1), which requires a reasonable assurance of control of radiological hazards to be effective for 1,000 years to the extent reasonably achievable, and in any case for at least 200 years.
2.4.5 References Army Corps of Engineers,1970. Imboratory Soil Testing, Engineering Manual EMI110-2-1906, November 1970.
Army Corps of Engineers,1972. SoilSampling, Engineering Manual EM 1110-2-1907, March 1972.
Nuclear Regulatory Commission,1978. " Laboratory Investigations of Soils for Engineering Analysis and Design of Nuclear Power Plants," Regulatory Guide 1.138. April 1978.
Nuclear Regulatory Commission,1979 " Site Investigations for Foundations of Nuclear Power Plants,"
Regulatory Guide 1.132 Revision 1. March 1979.
Seed, H.B., and I.M. Idriss,1971. "A Simplified Procedure for Evaluating Soil Liquefaction Potential,"
JSMFD 97(SM 9): 1249-1274,1971.
Seed, H.B., and I.M. Idriss,1982. " Ground Motions and Soil Liquefaction During Earthquakes,"
Earthquake Engineering Research Institute. Engineering Monograph: 5,1982.
Seed, R.B., and L.F. Harder,1990, "SPT-Based Analysis of Cyclic Pore Pressure Generation and Undrained Residual Strength," Proceedings of the H. Bolton Seed Memorial Symposium.
Berkeley, CA: University of Califomia, May 10-11, pp. 351-376,1990.
Shannon & Wilson,Inc., and Agbabian-Jacobsen Associates,1972, " Soil Behavior under Eanhquake 7.oading Conditions: State-of-the-Art Evaluation of Characteristicsfor Seismic Responses Analyses," U.S. Atomic Energy Commission Contract W-7405-eng-26,1972.
2.5 DISPOSAL CELL COVER ENGINEERING DESIGN l
l 2.5.1 Areas of Review l The staff shall review information provided related to disposal cell cover engineering design. including field exploration data, laboratory test results, design details, and constmetion and installation considerations pertinent to the geotechnical aspects of design and any associated geomembranes (i.e.,
disposal cell configuration and thickness, compaction requirements, gradations, permeability, and dispersivity).
2.5.2 Review Procedures NUREG-1620 2-20 t
r j
~ The reviewer shall examine the disposal cell design and engineering parameters to assess the geotechnical aspects of the disposal cell cover. Specific aspects of the review shall include the following l items:
(1) Determination that an adequate quantity of the specified borrow material has been identified at the borrow source.
l l (2) Confirmation that placement density, specific gravity, moisture content, dispersivity, and shrinkage properties used in the disposal cell design have been determined by suitable laboratory testing such that long-term stability standards will be met. (Note that permeability issues are discussed separately in SRP Section 2.7.)
(3) Confirmation that appropriate measures for controlling the effects of erosion, surface water flows, and vegetative root penetrations have been taken.
(4) Verification that the particle size gradation of the disposal cell cover material, bedding layers, other layers in the cover, and the rock layer are compatible to ensure stability against partici:
migration during the period of regulatory interest.
(5) Determination that the disposal cell has been designed to accommodate the effects of anticipated freeze-thaw cycles.
(6) Assessment, if bentonite amendment to the radon barrier material of the disposal cell cover is proposed, of whether supporting discussions define appropriate laboratory testing and field procedures associated with evaluating amended materials.
(7) Determination if the cracking potential of the disposal cell has been adequately addressed.
Cracking from both settlement and shrinkage shall be evaluated (this has been previously evaluated in SRP Section 2.3).
(8)' Assessment of the acceptability of plans for installation and use of any geomembranes.
(9) Confirmation that the information used in the disposal cell cover design appropriately reflects .j the staff findings on the information Irviewed using SRP Chapters 1,2,3, and 4.
Note that hydraulic conductivity aspects of the disposal cell cover design are assessed using SRP Section 2.7 and that review of the disposal cell design features is addressed in SRP Sections 2.2,2.3, and 2.4.
Review of the radon attenuation aspects of the disposal cell design is addressed in SRP Chapter 5.
2.5.3 Acceptance Criteria e The assessment of the disposal cell cover design and engineering parameters will be acceptable if it meets the following criteria:
2-21 NUREG-1620
e (1) Detailed descriptions of the disposal cell material types [e.g., Unified Soil Classification System (Holtz and Kovacs,1981)] and/or soil mixtures (e.g., bentonite additive) and the basis for their selection are presented.
An analysis is included that demonstrates that an adequate quantity of the specified borrow material has been identified at the borrow source. He information on borrow material includes boring and test pit logs, and compaction test data.
The soils that are considered suitable include the Unified Classification System classes CL, CH, SC, and CL-ML, with desirable characteristics and limitations as listed in Table 3-1 of the
" Construction Methods and Guidance for Sealing Penetration in Soil Covers" (Bennett &
Homz,1991; Bennett and Kimbrell,1991). The preferred material for the low permeability layers is inorganic clay soil. This soil should be compacted to a low saturated hydraulic conductivity of at least lx10 cm/sec.. For drainage layers, cobble types GW, GP, SP, and SW are recommended, with GW and GP being the preferred types (Bennett,1991).
Measures for resisting cracking, heaving, and settlement, and providing protection from burrowing animals, root penetration, and erosion over a long period of time are described.
(2) A sufficiently detailed description of the applicable field and laboratory investigations and testing that were completed, and the material properties (e.g., permeability, moisture-density relationships, gradation, shrinkage and dispersive characteristics, resistance to freeze-thaw degradation, cracking potential, and chemical compatibility, including any amendment materials) are identified (Army Corps of Engineers,1970; Army Corps of Engineers,1972; Fermulk and Hong,1990; NRC,1978; NRC,1979; Lee and Shen,1969; Spangler and Handy, 1982).
(3) Details (including sketches) of the disposal cell cover termination at boundaries, with any considerations for safely accommodating sub urface water flows are provided.
(4) A schematic diagram displaying various disposal cell layers and thicknesses is provided.
The particle size gradation of the disposal cell bedding layer and the rock layer must be established to ensure stability against particle migration during the period of regulatory interest (NRC,1982).
(5) The effect of possible freeze and thaw cycle on soil strength and radon barrier effectiveness is adequately considered (e.g., Aitken and Berg,1968).
If the region experiences prolonged freezing, the disposal cell cover may be affected by the freeze-thaw cycle. During freezing, ice crystals and lenses can form in the soil, causing heaving. On the other hand, during melting and thawing, the soil may lose its bearing capacity because of development of supersaturated conditions (Spangler and Handy,1982). Major factors affecting growth of ice in soil are the temperature below the freezing point, the capillary characteristics of the soil, and the presence of water. The reviewer will check whether the soil is susceptible to frost heave, considering that uniformly graded soils containing more than 10 NUREG-1620 2-22
{
- a percent of panicles smaller than 0.02 mm and well-graded soils with more than 3 percent of particles smaller than 0.02 mm are susceptible (H~oltz and Kovacs,1981; Spangler and Handy, 1982). After many freeze-thaw cycles, the soil may become a loose collection of aggregates with significantly reduced overall strength.
(6) A description (with sketches) of any penetrations (e.g., monitoring well) through the disposal cell system, including details of penetration sealing and disposal cell cover integrity, are provided. Bennett and Kimbrell (1991) suggests methods for seal design that are acceptable.
(7) An adequate analysis of the potential for development of cracks in the disposal cell cover as a result of differential settlement and shrinkage is provided. Note that cracking issues associated with settlement are discussed in SRP Section 2.3.3.
1 (8) An adequate description of the geomembranes and their major propenies (e.g., physical, mechanical, and chemical) is provided if low permeability geomembranes are proposed as a part of the disposal cell cover. Methods for installation of the membranes in accordance with the manufacturer's recommendations are discussed. The shear strength of the interface between compacted clay and geomembranes used in the stabilirj analyses under both static and dynamic loads is provided. An analysis of the expected service life of the geomembrane is provided.
(9) Information on site characterization, slope stability, settlement, and liquefaction used in the disposal cell cover design appropriately reflects the staffs evaluation, and, therefore, constitutes inputs that would contribute to the demonstration of disposal cell design compliance with the regulations.
2.5.4 Evaluation Findings If the staff's review as described in this SRP Section 2.5 results in the acceptance of the disposal cell cover design, the following conclusions may be presented in the TER.
NRC has completed its review of the information regarding the disposal cell cover design at the facility. This review included an evaluation using the revie w procedures in SRP Section 2.5.2 and acceptance criteria outlined in SRP Section 2.5.3.
The licensee has acceptably presented the disposal cell cover design by providing detailed descriptions of the disposal cell material types and/or soil mixtures, including the basis for their selection. The applicant has identified an adequate quantity of the specified borrow materian
- the borrow source. An acceptable schematic diagram displaying various disposal cell layers and thicknesses is provided. A description of the applicable field and laboratory investigations and testing is providec, including identification of material properties. The properties of the cover materials have been measured properly using standards such as ASTM, NRC, or U.S. Army Corps of Engineers. Details (including sketches) have been provided of (1) disposal cell termination boundaries; (2) penetrations, including sealing and disposal cell integrity; and (3) geomembranes and their physical, mechanical, and chemical properties. Methods ofinstallation 2-23 NUREG-1620 i
i ,
l l for the membranes have been discussed and the expected service life has been justified. The analysis of the potential for development of cracks in the disposal cell cover is acceptable.
On the basis of the information provided by the licensee on the disposal cell cover design at the facility, the staff has concluded that the disposal cell engineering parameters and associated conceptual and numerical models are acceptable and provide input to demonstration of o compliance with 10 CFR Part 40 Appendix A: (1) Critedon 4(c), which provides requirements for the I
embankment and cover slopes for tailings; (2) Criterion 4(d), which requires establishment of a self-sustaining vegetative cover or employment of a rock cover to reduce wind and water erosion to i
negligible levels, that individual rock fragments are suited for thejob, and that the impoundment surfaces are contoured to avoid concentrated surface runoff or abrupt changes in slope gradient; and (3) Criterion 6(1), which requires a reasonable assurance of control of radiological hazards to be effective for 1,000 years to the extent reasonably achievable, and in any case for at least 200 years.
l 2.5.5 References
. Aitken, G.W., and R.L. Berg,1%8. Digital Solution ofModified Berggren Equation to Calculate Depths offreeze or Thaw in Multi-layered Systems, Special Report 122, Cold Regions Research &
Engineering Laboratory, Hanover, NH,1%8.
Army Corps of Engineers,1970. Laboratory Soil Testing, Engineering Manual EM1110-2-1906, November 1970.
Army Corps of Engineers,1972. Soil Sampling, Engineering Manual EMI110-2-1907, March 1972.
Bennett, R.D., and R.C. Homz,1991. " Recommendations to the NRCfor Soil Cover Systems Over Uranium Mill Tailings and Low-Level Radioactive Wastes: laboratory and Field Testsfo- Soil Covers," NUREG/CR-5432, Vol. 2,1991.
Bennett, R.D., and A.F. Kimbrell,1991. " Recommendations to the NRCfor Soil Cover Systems Over Uranium Mill Tailings and Low-L.evel Radioactive Wastes: Construction Methodsfor Sealing Penetrations in Soil Covers," NUREGICR-5432, Vol. 3,1991.
Bennett, R.D.,1991. " Recommendations to the NRCfor Soil Cover Systems Over Uranium Mill Tailings and Low-Level Radioactive Wastes: Identification and Ranking of Soils
- for Disposal Facility Covers," NUREGICR-5432, Vol.1,1991.
Fermulk, N., and M. Haug,1990. " Evaluation of in Situ Permeability Testing Methods," ASCE Journal of GeotechnicalEngineering, 116(2):297-311, 1990.
Holtz, R.D., and W.D. Kovacs,1981. " An Introduction to Geotechnical Engineering," Englewood Cliffs, NJ: Prentice-Hall,1981.
NUREG-1620 2-24 1
p . ,
j j Lee, K.L., and C.K. Shen.,1969. " Horizontal Movements Related to Subsidence," Journal of Soil l Mechanics and Foundation Division 95(SM-1). New York, NY: American Society of Civil l Engineers,1969.
Nuclear Regulatory Commission,1978. " Laboratory Investigations of Soils for Engineering Analysis and Design of Nuclear Power Plants," Regulatory Guide 1.138. April 1978.
l Nuclear Regulatory Commission,1979. " Site Investigations for Foundatio:.s of Nuclear Power Plants,"
Regulatory Guide 1.132, Revision 1, March 1979.
Nuclear Regulatory Commission,1982. " Rock Riprap Design Methods and Their Applicability to Long-Term Protection of Uranium Mill Tailings impoundments," NUREGICR-2684, l982.
Spangler, M.G., and R.L. Handy,1982. Soil Engineering. New York, NY: Harper and Row,1982.
2.6 CONSTRUCTION CONSIDERATIONS 2.6.1 Areas of Review The staff shall review information on the geotechnical aspects of reclamation action construction. These l aspects should include details such as the sequence of construction activities, material specifications and placement procedures, and quality control (QC) aspects of the construction procedures. Th: geotechnical aspects of the planned construction operations shall be reviewed to identify any deviations from standard engineering practice for earthworks, including measures to protect against erosion and provisions for a vegetative cover.
2.6.2 Review Procedures The reviewc shall determine if all the tailings and contaminated materials at the site can be placed within the configuration of the proposed stabilized pile. The construction sequence shall be reviewed to verify the feasibility of achieving the intended final configuration of the tailings, particularly when tailings are to be relocated to new areas of the remediated pile and to determine whether the schedule for completion is reasonable.
The reviewer shall examine material placement, placement moisture content (drying, if needed),
placement density, and desired permeability to ensure that design specifications shall be met. If mixing of the fine tailings (slimes) with sand tailings is proposed, the specifications to control the mixture and the determination of the engineering properties of this mixture shall be examined for adequacy.
l The reviewer shall examine the proposed construction QC program to verify that adequate provisions i have been included to ensure that the construction shall be in accordance with the NRC-approved RP. In l
2-25 NUREG-1620
l k particular, details of the proposed testing and inspection program, including the type and frequency of tests proposed, shall be reviewed and compared with NRC guidance on testing and inspection.
Methods and schedules for emplacing the vegetative cover shall be reviewed to determine that they are reasonable, and that seeds for the planned vegetation are compatible with the local climate.
1 2.6.3 Acceptance Criteria The analysis of construction considerations will be acceptable if the following criteria are met:
(1) Engineering drawings are complete and clearly show the design features (e.g., embankments, ripraps, and channels).
. (2) Sources and quantities of borrow material are identified, are shown to have been adequately characterized and quantified through field and laboratory tests, and u demonstrated to be adequate for meeting the geotechnical design requirements for disposal cell (NRC,1978, 1979). The backgroand levels of contamination in the borrow materials, if any, is properly established.
(3) Methods, procedures, and requirements for excavating, hauling, stockpiling, and placing of contaminated and noncontaminated materials, and other disposal cell materials are provided and are shown to be consistent with commonly accepted engineering practice for earthen works (Department of the Navy,1982a,b; Denson, etal.,1987).
Material placement and compaction procedures are adequate to achieve the desired moisture content (drying, if needed) and placement density and permeability. Recommendations provided in NUREG/CR-5041 (Denson, et al.,1987) for gradation, placement, and compaction necessary to achieve design drainage rates and volumes, prevent intemal erosion or piping, and allow for collection and removal of liquids are acceptable. Compaction specifications include restricticas on work related to adverse weather conditions (e.g., rainfall, freezing condkion::,
etc.).
Specifications for controlling the mixture of fine tailings (slime) with sand tailings are consistent with commonly accepted engineering practice and testing programs for determination of engineering properties of this mixture.
(4) A plan for embankment construction is provided that demonstrates that embankments can be constructed in accordance with the design.
(5) Plans, specifications, and requirements for disposal cell compaction are supported by field and laboratory tests and analyses to assure stability and reliable performance.
(6) Testing and surveying programs to determine the extent of cleanup required are adequate.
The contamination cleanup plan includes the method for determining the extent of the contaminated area and a confirmation program to demonstrate that the contaminated material NUREG-1620 2-26
l has been removed. Details of the site cleanup (radiological aspects) are addressed in SRP Chapter 5.
(7) A plan for settlement measurement is provided that is satisfactory for producing representative settlement data throughout the area of the disposal cell. Settlement measurement stations are of sufficient coverage and are strategically placed to yield adequate information for determination of total, differential, and residual settlements. Monitoring monuments are designed to be durable. De reviewer shall also determine the reasonableness of the proposed monitoring frequency in acconlance with NRC (1983).
(8) It is shown that all tailings and contaminated mr,terials at the site can be placed within the planned configuration of the stabilized pilo (9) Procedures, specifications, and requirements for riprap, rock mulch, and filter production and placement are provided and are shown to be consistent with commonly accepted engineering practice and the design specifications (NRC,1977,1982).
(10) ne construction sequence is described and demonstrated to be adequate to achieve the intended configuration for the tailings, particularly when tailings are to be relocated to new areas of the reclaimed pile. It is shown that the proposed time to completion is reasonably achievable.
(11) De vegetation program or rock cover design is desenbed and demonstrated to be adequate (Wu,1984; NRC,1982).
(12) Appropriate QC provisions are provided to ensure that the construction will be in accordance with the RP. De descriptions of the methods, procedures, and frequencies by which the i onstruction materials and activities are to be tested and inspected are reasonable and that appropriate records will be maintained (NRC,1983).
(13) Tailings are placed below grade or the licensee has demonstrated that the above grade disposal design provides reasonably equivalent isolation of the tailings from natural erosional forces.
Tailings pile topographic features take into account wind protection and vegetation cover.
2-27 NUREG-1620 I
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2.6.4 Evaluation Findings l If the staff's review as described irs this section results in the acceptance of the licensee's proposed construction considerations, the following conclusions may be presented in the TER.
l NRC has completed its review of the constmction considerations proposed by the licensee at the i facility. This review included an evaluation using the review procedures in SRP f Section 2.6.2 and acceptance criteria outlined in SRP Section 2.6.3. I l
The licensee has acceptably described the construction considerations by: (1) providing complete engineering drawings showing all design features; (2) describing sources and quantities of borrow material, including acceptable field and laboratory testing; and (3) identifying methods, procedures. and requirements for excavations, haulage, stockpiling, and placement of materials and demonstrating that all j are consistent with accepted engineering practices for earthen works. An acceptable plan for j embankment constmenon is provided. Disposal cell compaction plans are supported by field and i I
laboratory tests that assure stability and performance. The licensee has an acceptable program to determine the extent of cleanup using appropriate testing and surveying programs. An acceptable plan for settlement measurement is prwided, including: (1) proper coverage and placement of settlement q measurement stations; (2) durable monitoring monunents; and (3) reasonable monitoring frequencies. ;
All tailings and contaminated materials have been demonstrated to fit within the planned configuration !
of the stabilized pile. Procedures, specifications, and requirements for riprap, rock mulch, and filters are ;
provided and are shown to be consistent with commonly accepted engineering practices and design ,
specifications. An acceptable construction sequence, including a reasonable time to completion, has been l described. An acceptable vegetation program or rock cover design is proposed. Appropriate QC l provisions are in place to ensure that construction will be in accordance with the reclamation plan and l that appropriate records will be maintained. I On the basis of the information provided in the application, and the detailed review conducted of the j constructica considerations at the facility, the staff has concluded that the construction considerations and associated conceptual and numerical models provide input to a demonstration of compliance with 10 CFR Part 40, Appendix A: (1) Criterion 4(c), which provides requirements for the embankment and cover slopes for tailings; (2) Criterion 4(d), which requires establishment of a self sustaining vegetative cover or employment of a rock cover to reduce wind and water erosion to negligible levels, that individual rock fragments are suited for the job, and that the impoundment surfaces are contoured to avoid concentrated surface runoff or abmpt changes in slope gradient; and (3) Criterion 6(1), relating to providing reasonable assurance of control of radiological l hazards to be effective for 1,000 yerrs to the extent reasonably achievable, and in any case for at least j 200 years. l i
2.6.5 References l Denson, R.H.,gul,1987. " Recommendations to the NRCfor Review Criteriafor Alternative Methods of Low-LevelRadioactive Waste Disposa! " NUREGICR-5041,1987.
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Department of the Navy,1982a. Foundations and Eanh Structures, NAVFAC DM 7.2, May 1982.
Depanment of the Navy,1982b. Soil Dynamics, Deep Stabilization, and Special Geotechnical Construction NAVFAC DM 7.3, May 1982.
Nuclear Regulatory Commission,1977. "Desig 1, Construction, and Inspection of Embankment Retention Systems for Uranium Mills," Regulatory Guide 3.11, Revision 2, December 1977.
Nuclear Regulatory Commission,1978. " Laboratory Investigations of Soils for Engineering Analysis and Design of Nuclear Power Plants," Regulatory Guide 1.138, April 1978.
Nuclear Regulatory Commission,1979. " Site Investigations for Foundations of Nuclear Power Plants,"
Regulatory Guide 1.132, Revision 1. March 1979.
Nuclear Regulatory Commission,1982. " Rock Riprap Design Methods and Their Applicability to Long-Term Protection of Uranium Mill Tailings impoundments," NUREGICR-2684,1982.
Nuclear Regulatory Commission,1983. "Geotechnical Quality Control: Low-livel Radioactive Waste and Uranium Mill Tailings Disposal Facilities," NUREGICR-3356,1983.
Wu, T.H.1984. Effect of Vegetation on Slope Stability, " Soil Reinforcement and Moisture Effects on Slope Stability," Transportation Research Record %5, Transportation Research Board, National Research Council,1984. ,
i 2.7 DISPOSAL CELL HYDRAULIC CONDUCTIVITY i 2.7.1 Areas of Review
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'Ihe staff shall review test results, , alculations, the technical bases for disposal cell design hydraulic l
conductivity values, the field testing program, and the QC program.
2.7.2 Review Procedures The reviewer shall examine the geotechnical design aspects of the disposal cell to ensure that the ,
disposal cell cover component has a minimal hydraulic conductivity, to limit radon emissions from, and I water infiltration into, stabilized mill tailings. The geotechnical reviewer shall coordinate with the water resources protection reviewer (see SRP Chapter 4) to ensure that regulatory requirements for groundwater protection can be met by the proposed radon barriu.
The reviewer shall verify that an adequate technical basis has been provided for the design hydraulic conductivity (K) value for the disposal cell cover, For any situation in which a K<10 cm/see is proposed by the licensee, the staff shall verify that either a test fill program will be undenaken to verify the constructability to achieve the desired K value, or the RP narrative and accompanying analyses have adequately demonstrated the acceptability of the design K value, considering some technical papers on 2-29 NUREG-1620 o_ - . . .
this subject (e.g., Rogowski,1990; Panno, et al.,1991; Benson and Daniel,1990). If the RP acceptably demonstrates that field testing is not required, the reviewer shall document the technical basis in the TER. If field testing is required, the staff shall ensure that the test fill specifications require that the hydraulic conductivity value be v ified by in-place testing with double-ring infiltrometers or other approved methods.
The test reviewer shall examine the test fill construction plan and verification program for adequacy, including such aspects as: (1) use of proper procedures and equipment for placement and compaction operations; (2) verification of the material and thickness for the barrier test zone; (3) comparison of gradation, bentonite amendment, and moisture / density testing with specifications; and (4) review of the QC plan.
2.7.3 Acceptance Criteria The analysis of disposal cell hydraulic conductivity will be acceptable if it meets the following criteria.
(1) A sufficient technical ba-is is provided for the design hydraulic conductivity (K) value for the disposal cell.
The hydraulic conductivity is minimized by compacting fine-grained soil for a sufficient depth ab - .he stabilized tailings. Natural borrow soils having insufficient silt and clay content to effectively reduce the hydraulic conductivity of the barrier can be amended with bentonite for
. proved effectiveness. (Note that construction issues are discussed separately in SRP Section 2.6).
(2) A field testing pren a adequate to verify the constructability of the disposal cell with a design hydraulic conductivity K<10~7 cm/sec is provided unless the RP demonstrates that field testing is not required (Benson and Daniel,1990; NRC,1979).
To meet to the U.S. Environmental Protection Agency (EPA) groundwater standards, designers of disposal cells for mill tailings sites are proposing increasingly smaller design hydraulic conductivity (K) values. It is not unusual for laboratory permeability test values to yield results of 10 4to 10" em/sec. Such tests are performed on compacted soil samples considered by the design engineer to represent the soil to be used for the disposal cell. However, several recent technical papers (Rogowski,1990; Panno, et al. 1991; Benson and Daniel,1990) have raised serious questions conceming the exclusive use of laboratory te> ting for demonstrating 4
hydraulic conductivity values in those cases in which a radon barrier K-value less than 10 cm/sec is specified. On the basis of these technical papers, field testing is necessary to confirm the radon barrier hydraulic conductivity, since construction operations and soil material variability can create preferred pathways, joints, seams, holes, and flaws that effectively increase the value of this parameter. Test results should take into consideration the variability and uncertainty in site conditions and material properties.
(3) An appropriate QC program is followed for the field testing to determine hydraulic conductivity (NRC,1983).
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! For all cases in which K<10-' cm/sec and the test fill program requirement has been defined,
- specifications and related documents (Remedial Action Inspection Plan, etc.) will require an adequate QC program. An acceptable QC program should provide mechanisms to ensure that as-built construction duplicates the test fill construction techniques on the cell barrier (NRC, 1983). The objective of the QC program will be to provide assurance that uniform and high-quality construction of the cell barrier has been achieved.
2.7.4 Evaluation Findings J If the staff's review as described in SRP Section 2.7 results in the acceptance of the disposal cell hydraulic conductivity, the following conclusions may be presented in the TER. {
NRC has completed its review of the information concerned with the disposal cell hydraulic conductivity at the facility. This review included an evaluation using the review procedures in SRP Section 2.7.2 and acceptance criteria outlined in SRP Section 2.7.3.
The licensee has acceptably evaluated the disposal cell cover materials
- hydraulic conductivity by providing a sufficient technical basis for the design K-value for the disposal cell. A field testing program adequate to verify the constructability of the disposal cell with a hydraulic design conductivity of K<10 -'
cm/sec is presented. The applicant followed an acceptable QC program for the field testing to determine the hydraulic conductivity.
On the basis of the information provided in the application, and the detailed review conducted of the disposal cell hydraulic conductivity at the feility, the staff has concluded that the disposal cell hydraulic conductivity and associated conceptual and numerical models provide an acceptable input to the demonstration of compliance with 10 CFR Part 40, (1) Criterion 4(c), which provides requirements for the embankment and cover slopes for tailings; (2) Criterion 6(1), relating to providing reasonable assurance of control of radiological hazards to be effective for 1,000 years to the extent reasonably achievable, and in any case for at least 200 years.
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1 2.7.5 References Benscm, C.H., and D.E. Daniel,1990. " Influence of Clods on Hydraulic Conductivity of Compacted Clay," ASCEJoumalofGeotechnicalEngineering 116(8):1231-1248,1990.
Nuclear Regulatory Commission,1979. " Site Investigations for Foundations of Nuclear Power Plants,"
Regulatory Guide 1.132, Revision 1, March 1979.
Nuclear Regulatory Commission,1983. "Geotechnical Quality Control: Low-Level Radioactive Waste l and Uranium Mill Tailings Disposal Facilities," NUREGICR-3356,1983. l Panno, S.V., et al.1991. " Field-Scale Investigation of Infiltration Into a Compacted Soil Liner," Groural Water 29(6): 914-921,1991.
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Rogowski, A.S.,1990. " Relationship oflaboratory- and Field-Determined Hydraulic Conductivity in Compacted Clay layer," EPAl600/S2-90/025, Cincinnati, OH: Risk Reduction Engineering i Laboratory,1990.
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NUREG-1620 2-32
1 3.0 SURFACE WATER HYDROLOGY AND EROSION PROTECTION l'
The staff shall review hydrologic information, analyses, and design details presented in the RP and/or its supporting documents to ensure that the plan provides long-term erosion protection in accordance with the requirements in 10 CFR Pan 40, Appendix A. Major areas of review are described in SRP Sections 3.1 through 3.5.
The surface water hydrology and erosion protection review plan is structured somewhat differently than the review plans for other technical areas, principally because detailed guidance for the design and review of erosion protection has been previously developed by the staff. This guidance was included in the Final Staff Technical Position (FSTP), " Design of Erosion Protection Covers for Stabilization of Uranium Mill Tailings Sites." (The draft FSTP was developed in 1989 and finalized in 1990, (NRC, 1990), after public comments were received.) In addition, the staffis currently developing modifications and improvements to the FSTP, and will publish a new repon that updates the FSTP. This new report will be published as NUREG-1623, " Design of Erosion Protection for Long-Term Stabilization," (NRC, 1998). Because very detailed guidance is available in these documents, the infonnation contained in the FSTP or NUREG-1623 will not be repeated in this SRP chapter. Rather, this SRP merely references the FSTP and NUREG-1623 as sources of design guidance for licensees and review guidance for the naff.
The staff will use these documents in its review of reckmation plans to independently estimate flood ,
potential and erosion protection requirements. Funher. the technical bases provided in these documents l will be used to determine the acceptability of various / esign Spproaches.
NUREG-1623 will provide several new methods for e /aluating erosion protection designs that were not included in the FSTP. These new methods include detailed techniques for assessing (1) channel outlets, (2) sedimentation in diversion channels, (3) construction specifications and quality assurance / quality control (QA/QC) programs, (4) aprons and toes, and (5) side slopes and top slopes.
NUREG-1623 will also revise and improve several sections of the FSTP, on the basis of recent staff i experience and new technical studies, and will provide improved methods for assessing (1) gully l intrusion, (2) design of sacrificial slopes, (3) rock durability, and (4) vegetative covers. In general, 1 NUREG-1623 will provide detailed guidance for the hydrologic and erosion protection aspects of the RP l that will be reviewed by the staff. Although not included with this draft version of the SRP, NUREG-1623 will be included in the final version.
It should be emphasized that the FSTP and NUREG-1623 suggest several (of many pessible) acceptable methods for implementing the requirements of 10 CFR Part 40. However, as clearly stated in those l documents, use of these design methods is not required, and the licensee may propose alternatives that are technically supported.
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3-1 NUREG-1620 l
3.1 HYDROLOGIC DESCRIPTION OF SITE 3.1.1 Areas of Review Criterion 1 of Part 40, Appendix A, addresses the general goals of siting and designing facilities to provide for permanent isolation of tailings, and minimizing the potential for dispersion by natural forces, without the need for active maintenance. Information presented in SRP Section 3.1 will be used in later SRP sections to assess the ability of the site and the site design to meet this and other requirements of Part 40.
The staff will review hydrologic site characterization information, including (1) identification of the relationships of the site to surface-water features in the site area and (2) identification of mechanisms, such as floods and dam failures, that may require special design features to be implemented. This review requires identification of the hydrologic characteristics of streams, lakes (e.g., location, size, shape, drainage area), and existing or proposed water control structures that may adversely affect the long-term stability of the site design features.
3.1.2 Review Procedures Tra information normally presented is not amenable to independent verification, except through cross-checks with available publications related te hydrologic characteristics of the site region and through observation during site visits. The review procedure consists of evaluating the completeness of the information and data, by sequential comparison with information available from references.' On the basis of the description of the hydrosphere (e.g., geographic location and regional hydrologic features),
potential site flood mechanisms are identified.
The staff will also analyze geomorphic considerations, as described in SRP Chapter 1. On the basis of these analyses, the staff will estimate the potential for geomorphic instability to occur and to have a significant effect on the ability of the site and its protective features to prevent flood intmsion and erosion over a long period of time. If geomorphic problems are identified, the staff will give particular attr,ntion to several areas of the design, depending on site conditions and potential for geomcrphic changes to occur. These areas include (1) the apron and toe of the disposal cell,(2) intersection of natural gullies with erosion protection features, and (3) diversbn channel outlets. A detailed discussion of the erosion protection design for these and other features is given in SRP Section 3.4.2.
3.1.3 Acceptance Criteria Acceptance of the information presented is based on a qualitative evaluation of the completeness and quality of information, data, and maps. The description of stmetures, facilities, and erosion protection designs should be sufficiently complete to allow independent evaluation of the impact of flooding and intense rainfall. Site topographic maps should be of good quality and of sufficient scale to allow independent analysis of pre- and post-construction drainage pattems.
The characterization of hydrologic information will be acceptable if the RP contains sufficient information for the staff to independently evaluate the hydraulic designs presented. In general, detailed i
NUREG-1620 3-2
, l information is needed for each method that is used to determine the hydraulic designs and erosion protection provided to meet NRC regulations. NUREG-1623 discusses acceptable methods for designing erosion pretection to provide reasonable assurance of effe:tive long-term control and thus meet NRC requirements. NUREG-1623 also provides discussions and technical bases for use of specific criteria to meet the 1,000-year longevity requirement, without the use of active maintenance. Specific design methods are provided and form the primary basis for staff review of erosion protection designs. These criteria were derived from regulatory requirements, other regulatory guidance, staff experience, and various technical references.
3.1.4 Evaluation Findings I
If the staff's evaluation of hydrologic and hydraulic engineering aspects of the RP confirms that the I information provided in SRP Section 3.1 acceptably characterizes the site and the site design features, the following conclusions may be presented in the TER.
The NRC staff has completed its review of the information provided to assess the flooding potential at the site. This review included an evaluation using the review procedures in SRP Section 3.1.2 and )
acceptance criteria outlined in SRP Section 3.1.3. I On the basis of its review, the staff has concluded that (1) the flood analyses and investigatiom adequately characterize the flood potential at the site, (2) the analyses of hydraulic designs are
, appropriately documented, and (3) the general reclamation plan with respect to surface-water hydrology i l and erosion considerations represents a feasible plan for meeting the requirements of 10 CFR Part 40, j Appendix A. The characterization of flood potential and the documentation of the site design meet the l requirements of Criterion 1 of 10 CFR Part 40 Appendix A. related to presenting a design that provides for permanent isolation of tailings and minimizes disturbance and dispersion by natural forces.
3.1.5 References Nuclear Regulatory Commission, " Design of Erosion Protection Covers for Stabilization of Uranium Mill Tailings Sites," Final Staff Technical Position,1990.
Nuclear Regulatory Commission, " Design of Erosion Protection for Long-Term Stabilization,"
Draft NUREG-1623,1998.
3.2 FLOODING DETERMINATIONS l 3.2.1 Areas of Review The staff will assess the flooding potential for the site, including a determination of precipitation potential, precipitation losses, runoff response chari.cteristics, and peak flow estimates for the probable maximum flood (PMF) or project design flood (if a flood less than the PMF is used). The staff will l review design analyses, including: (1) the analyses and justification for the use of a flood less than the PMF, if applicable; (2) the probable maximum precipitation (PMP) potential and resulting runoff for site 3-3 NUREG-1620 I
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drainage and for drainage areas adjacent to the site; and (3) the modeling of physical rainfall and runoff processes to estimate flood conditions at the site.
The assessment of flooding also will include a review of possible geomorphic changes that could affect the erosion protection design for the site. As applicable, the staff will review the following: (1) identification of types of geomorphic instability; (2) changes to, and impacts associated with, flooding and flood velocities, from geomorphic changes; and (3) mitigative measures to reduce or control geomorphic instability. Review of this information is necessary to determine the acceptability of hydraulic engineering designs to mitigate the geomorphic conditions.
The assessment of flooding will also include a review of potential dam failures, if upstream reservoirs exist. Peak water levels, flood routing procedures, and velocities will be reviewed in the determination of potential hazards because of failure of upstream water control structures from either seismic or hydrologic causes. If an existing analysis concludes that seismic or hydrologic events will not cause failures of upstream dams and produce the governing flood at the site, the analysis will be reviewed to verify that information that supports such a conclusion (e.g., record of contact with dam designers) is included. If an analysis is provided that concludes that a dam failure flood from a PMF or a seismically induced flood is the design- basis flood, the computations will be reviewed to verify that appropriate and/or conservative model input parameters have been used.
3.2.2 Review Procedures The evaluation of flooding is, for review purposes, separated into two parts: (1) flooding on large adjacent streams, as applicable, and (2) localized fimding m drainage channels and protective featu w.
The acceptability of using the PMF as the design Lood event is presented in NUREG-1623 (NRC,1991 -
The rrview procedure for evr' ting a PMP/PMF event is outlined in SUREG-M23. For large drainace j areas ?MF estimates approved by the Corps of Engineers and contained in published or unpublished I renom f that agency, or generalized estimates, may be used instead of independent staff-developed c us. The staff will also assess flood history in the site area by examinir g historic regional flood dom. For many areas, historic flood peaks could be a small percentage of the PMF. If the historic maximum floods exceed or closely approximate the proposed PMF -imates, the staff will perform a detailed evaluation to determine the basis for the estimates. The staff will compare basin lag times, rainfall distributions, soil types, and infiltration loss rates to determine if there is a logical basis for the PMF values being less than historic floods. Without such estimates, the staff will generally use Corps of Engineers' models to independently estimate PMF discharge and water levels at the site. If detailed computer models are used, the staff will review the adequacy a 'he various input parameters to the model, including, but not limited to, the following: drainage > ~ lag times and times of concentration, design rainfall, incremental rainfall amounts, temporal distribution of incremental rainfall, and runoff / infiltration relationships.
Information pertinent to computation of the design flood should be submitted in sufficient detail to enable the staff to perform an independent flood estimate. Acceptance of the analysis is based on acceptability of model input parameters, general agreement of the staff's and the RP estimates of flood levels and peak discharges; and the adequacy of the computational methods used for such estimates. )l For dam failures, the staff will review the analyses provided in the RP or will independently estimate the j NUREG-1620 3-4
l peak f!ows at the site. The acceptable " worst conditions" that should be postulated in the analysis of upstream dam failures are (1) an approximate 25-year flood on e. normal operating reservoir pool level coincident with the dam-site equivalent of the earthquake for which the remedial action project is designed;(2) a flood of about one-half the severity of a PMF on a normal reservoir pool level coincident with the dam-site equivalent of one-half of the earthquake for which the remedial action project is designed; and (3) a PMF (or design flood) on a normal reservoir pool. Conditions (1) and (2) are applied when the dam is not designed with adequate seismic resistance; condition (3) is applied when the dam is not designed to safely store or pass the design flood. Often, it may be much easier to perform simplified flood analyses assuming a dam failure, rather than detailed analyses of the seismic resistance of a dam.
In such cases, the staff will review those simplified flood analyses using the procedures outlined in SRP Section 3.3.4.
In those cases in which it is documented that it is clearly impractical to design erosin protection feature:.
for an occurrence of the PMF, the staff will evaluate the information provided in the RP using procedures presented in Appendix B of the FSTP (NRC,1990) or NUREG-1623. These documents contain detailed information regarding justification of a stability period ofless than 1,000 years. In general, a proposed design based on less than a PMF event must provide reasonable assurance of meeting the stability requirement of 200 years. The ability of the design to resist such flood events is independently checked and evaluated by the staff to assure that minimt;m NRC requiremenn are met.
In the detailed review of flooding, the staff will carefully consider several factors that are important in determining a local PMP/PMF event. These factors include the following:
(1) Determination of Design Rainfall Event. The staff will consult appropriate hydrometeorological reports and determine that correct values of the 1-hour and 6-hour PMP events, as applicable, have been determined.
(2) Infiltration Losses. The staff will check calculations to verify that appropriate values ofinfiltration have been selected.
e (3) Times of Cona tion. The staff will verify that appropriate methods (depending on the slope, configuration, et : 'iave been selected. The staff will independently verify that the methods selected compare . :asonably well v4t h various velocity-based methods.
(4) Rainfall Distributions. The str'f will verify that the rainfall distributions (particularly the 2%-
minute,5-minute, and 15-minute distributions) compare well with the distributions suggested in NUREG-1623.
For dam failures, the acceptability and conservatism of the estimates of flood potential and water levels are reviewed. In general, depending on the potential for flooding, the staff will verify that the dam failure analyses are either realistic or conservative by determining locations and sizes of upstream dams, assuming an instantaneous failure (complete removal) of the dam embankment and computing the peak outflow rate.
If this simplified analysis indicates a potential flooding problem, the analysis may be repeated using more refined techniques, and additional information and data may be requested. Detailed failure models, such as those of the Corps of Engineers and National Weather Service, are used to identify the outflows, 3-5 NUREG-1620
e-failure modes, and resultant water levels at the site.
If a flood less than a PMF can cause dam failure and is proposed as the design basis flood, the review procedures outlined above are employed to determine the impracticality of designing for a PMF and to determine the acceptability of the flood used.
3.2.3 Acceptance Criteria In general, designs that conform to the suggested criteria in NUREG-1623 will be found acceptable.
This NUREG discusses acceptable methods for designing erosion protection to provide reasonable assurance of effective long-term control and to meet NRC requirements. It also provides discussions and technical bases for use of specific criteria to meet the 1000-year longevity requirement, without the use of active maintenance. Acceptable design methods are presented and form the primary basis for staff review of erosion pretection designs. These methods were derived from regulatory requirements, other regulatory guidance, staff experience, and various technical studies.
3.2.4 Evaluation Findings If the staff's evaluation of hydrologic and hydraulic engineering aspects of the RP confirms that the assessments of flooding are acceptable, the following conclusions may be presented in the TER.
The staff has completed its review of the information provided to assess the flooding potential at the site. This review included an evaluation usinr the review procedures in SRP Section 3.2.2 and acceptance criteria outlined in SRP Section 3.2.3. On !!'e basis of its review, the staff concludes that the flood analyses and investigations adequately characterize the flood potential at the site and that the surface water hydrology and flooding considerations represent a feasible plan for meeting the requirements of 10 CFR Part 40, Appendix A.
The mill tailings at the site will be protected from flooding and erosion by an engineered rock riprap layer that has been des:gned in accordance with the guidance suggested by the staff. Flood analyses provided by the licensee demonstrate that this erosion protection is adequate, based on (1) selection of proper rainfall and flooding events; (2) selection of appropriate parameters for determining flood discharges; and (3) computation of flood discharges, using appropriate and/or conservative methods.
The licensee provided analyses to show that the site is located in an area rarely flooded by offsite floods and that it is protected from direct onsite precipitation and flooding. The erosion protection is large enough to resist flooding from the shallow depths and minimal forces of floods occurring from a PMF in the upstream drainage area. The st ff therefore concludes that the erosion potential at the proposed site ;
has been acceptably minimized, since any flooding at the site is mitigated by the erosion protection, and the forces associated with offsite floods are minimal. The staff also concludes that because the rainfall and flooding events have very low probabilities of occurrence over a 1,000-year period, no damage to ,
erosion protection is expected from these, or more frequent, events. Therefore, maintenance or repair of damage will not be necessary.
NUREG-1620 3-6 1
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On the basis of a review of the information provided for the site, the staff concludes that the flood analyses radbute to meeting the requirements of 10 CFR Pan 40, Appendix A: Criterion 1, requiring that e ,sion, disturbance, and dispersion by natural forces over the long term are minimized and that the tailings are disposed of in a manner that does not require active maintenance to preserve conditions of the site; Criterion 4(a), requiring that rpstream rainfall catchment areas are minimized to decrease erosion potential and to resist floods that could erode or wash out sections of the tailings disposal area; Criterion 6, requiring that the design be effective for a period of 200 -1,000 years; and Criterion 12, requiring that active maintenance is not necessary to preserve isolation.
3.2.5 References Nuclear Regulatory Commission,1990. " Design of Erosion Protection Covers for Stabilization of Uranium Mill Tailings Sites." Final Staff Technical Position.
Nucle r Regulatory Commission,1998. *" Design of Erosion Protection for Long-Term Stabilization," Draft NUREG-1623.
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- NUREG-1523 updates the FSTP, based on experience gained in the Title I and Title II programs and on .
additional research in the area of erosion protection design. Specific references related to design, analysis, and information needs for the RP are discussed in these documents. A general reference list is provided in SRP Section 3.6.
3-7 NUREG-1620
33 WATER SURFACE PROFILES, CHANNEL VELOCITIES, AND SHEAR STRESSES !
l 33.1 Areas of Review The staff shall estimate the flood levels, velocities, shear stresses, and magnitudes, as described below.
Staff estimates may be made independently from basic data, by detailed review and checking of the RP analyses, or by comparison with estimates made by others that have been previously reviewed in detail. I The evaluation of the adequacy of the estimates is a matter of engineering judgment, and is based on the i confidence in the estimate, the degree of conservatism in each parameter used in the estimate, and the relative sensitivity of each parameter as it affects the flood level, flood velocity, or design of the erosion i I
protection.
Depending on the type of computational models used, the staff shall review the model, including the determination of flooding depths, channel velocities, and/or shear stresses used to determine riprap sizes ,
needed for erosion protection. The staff shall review the various detailed computations for each model l and will review the acceptability of the input parameters to the model.
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33.2 Review Procedures .
Using the guidance presented in NUREG-1623, (NRC,1998) the staff shall verify that localized flood depths, velocities, and shear stresses used in models for rock size determination or soil cover slope analysis are acceptable. For offsite flooding effects, the staff will verify that computational models have -
been correctly and appropriately used and that the output from the model has been correctly interpreted. j The staff will verify that acceptable models and input parameters have been used in all the various j portions of the flood analyses and that the resulting flood forces have been adequately acconunodated.
i 3.3.3 Acceptance Criteria In general, designs that conform to the suggested criteria in NUREG 1623 will be found acceptable.
NUREG-1623 discusses acceptable methods for designin; erosion protection to provide reasonable assurance of effective long-term control and to meet NRC requirements. This document also provides l
discussions and technical bases for use of specific criteria to meet the 1,000-year longevity requirement, q without the use of active maintenance. Specific design methods are presented, and reasonable similarity to these methods forms the primuy basis for staff acceptance of erosion protection designs. These criteria were derived from regulatory requirements, other regulatory guidance, staff experience, and various technical references.
33.4 Evaluation Findings j l
If the staff's evaluation of hydrologic and hydraulic engineering aspects of the RP confirms that the l assessments of flooding are acceptable, the following conclusions may be presented in the TER.
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The staff has completed its review of the infom1ation provided to assess the flooding models at the site. His review included an evaluation using the review procedures in SRP Section 3.3.2 and acceptance criteria outlined in SRP Secion 3.3.3. On the basis of its review, the staff concludes that flood velocities and forces associated with flooding at the site have been acceptably computed.
The mill tailings will be protected from flooding and erosion by an engineered rock riprap layer that has been designed in accordance with the guidance suggested by the staff. Flood ane! - tovided by the licensee demonstrate that adequate protection is provided by (1) selection of p- Jels to assess j rainfall and flooding events, (2) selection of appropriate parameters for model s 4 mining flood f forces, and (3) computation of flood forces using appropriate and/or conservati vis.
The staff considers that the riprap layers proposed will not require active maintenance over the 1,000- I year design life, because the licensee adopted models that conservatively compute flood forces used to !
design the erosion protection. Thus, the use of conservative design parameters will result in no damage !
to the erosion protection designed using those methods. The staff further concludes that the hydraulic design features are sufficient to protect the tailings from flood forces that are very large and have very low probabilities of occurrence over a 1,000-year period. Therefore, maintcaance of the rock layers will not be necessary.
The staff concludes that the analyses and models used at the site contribute to meeting the requirements of 10 CFR Part 40, Appendix A: (1) Criterion 1, requiring that erosion, disturbance, and dispersion by natural forces over the long term are minimized and that the tailings are disposed of in a manner that does not require 2ctive maintenance to preserve conditions of the site; (2) Criterion 6(1),
requiring the design to be effective for a period of 200 -1,000 yee2s; and (3) Criterion 12, requiring that i active ongoing maintenance is not necessary to preserve isolation of the tailings.
3.3.5 References Nuclear Regulatory Commission,1990. " Design of Erosion Protection Covers for Stabilization of Uranium Mill Tailings Sites," Final Staff Technical Position.
Nuclear Regulatory Commission * " Design of Erosion Protection for Long-Term Stabilization,"
Draft NUREG-1623.
3.4 EROSION PROTECTION DESIGN 3.4.1 Areas of Review f
Design details and analyses pertinent to the following aspects of erosion protection will be reviewed, as applicable:
(1) Erosion protection for slopes and channel banks to protect ageinst flooding from nearby large streams; (2) Erosion protection for the top and side slopes of the pile; 3-9 NUREG-1620
1 (3) Ert.sion protection for the apron / toe area of the side riope; (4) Erosion protection for drainage and diversion channels, including channel outlets; (5) Durability of the erosion protection; and (6) Construction considerations, including specifications, QA programs, quality control (QC) programs, and inspection programs.
i 3.4.2 Review Procedures The staff will check the analyses in the RP or perform independent review analyses of floods, flood velocities, and rock durability according to the guidelines provided in NUREG-1623 (NRC,1998). If the design assumptions and calculations are reasonable, accurate, and/or compare favorably with independent staff estimates, the designs are found acceptable.
3.4.2.1 Banks of Natural Channels The staff will review designs for riprap to be placed on the side slopes of a reclaimed pile or on natural channel banks to protect against erosive veloci*.ies from floods on large rivers. Guidance is provided in NUREG-1623 for assessing floods, determining input parameters to models, and deterrrining riprap requirements.
3.4.2.2 Top Slope and Side Slopes The staff will review input parameters to calculations and models according to the recommendations given in NUREG-1623 and referenced technical procedures. The staff will assess the design flow rate, the depth of flow, angle of repose, specific gravity, and other parameters. For both the top and side slopes, the rock sizes will be checked using the recently developed, simplified procedures discussed in NUREG-1623.
- NUREG-1623 updates the FSTP, based on experience gained in the Title I and Title II programs and on additional research in the area of erosion protection design. Specific references related to design, analysis, and information needs for the RP are discussed in these documents. A general reference list is provided in SRP Section 3.6.
i 3.4.2.3 Apron / foe The review of the design of the apron and toe is accomplished by verifying that several design features in this area have been properly designed, in accordance with the recommendations provided in NUREG-NUREG-1620 3-10 i
l
1623, For the lower end of the side slope where it meets the toe, the staff will verify that proper consideration has been given to the potential occurrence of increased shear force.; resulting from turbulence and energy dissipation produced by hydraulic jumps, when the flow transitions from supercritical to suberitical. The staff will verify that appropriate design criteria have been used to increase the rock size to account for the increased velocities or shear fortes.
For the main area of the toe, the staff will assure that appropriate methods have been used to design the riprap, depending on the magnitude of the slope of the toe.
l For the downstream end of the toe, the staff will verify that acceptable assumptions have been made regarding the assumed collapse of the rock into scoured areas to prevent gully intrusion. Flow concentrations, collapsed slopes, and computational models will be evaluated.
For the natural ground area at the downstream end of the toe, the staff will verify that appropriate methods have been used to compute scour depths and that natural erosion will not adversely affect long-l term stability.
l 3.4.2.4 Diversion Channels Using the criteria and guidance presented in NUREG-1623, the staff will evaluate the design of diversion channels in several critical areas.
For the main channel area, the staff will verify that appropriate models and input parameters have been used to design the erosion protection. The staff will assure that flow rates, flow depths, and shear stresses have been correctly computed.
For the channel side slopes, the staff will verify that the side slopes are capable of resisting flow velocities and shear stresses from flows that occur directly down the side slope. This occurs often when diversion channels are constructed perpendicular to natural gullies (which discharge into the diversion channel). The shear forces in these locations often greatly exceed the forces produced by flows in the channel, particularly when the slope of the natural ground in the area is greater than the slope of the diversion channel.
For the outlet of the diversion channel, the staff will evaluate the design of erosion protection to assure that erosion in the discharge area (normally a natural gully, swale, or channel) has been adequately addressed. Designs similar to apron / toe designs will be evaluated t.o detennine their resistance to erosion. NUREG-1623 discusses acceptable methods for designing channel outlets.
For the entire length of the diversion channel, the staff will e zatuate the effects of sediment accumulations on flow velocities, channel capacity, and need for increased rock size. Particular attention will be given to designs in which steep natural streams discharge into relatively flat diversion channels, greatly increasing the potential for blockage ose channel. NUREG-1623 discusses acceptable methods for assessing sedimentation in diversion chant 3.4.2.5 Rock Durability 3-11 NUREG-1620
=
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The staff will review the results of durability testing of proposed rock sources to assure that durable rock will be provided. NUREG-1623 provides a detailed method for evaluating rock quality for various locations and applications.
3.4.2.6 Construction Considerations The staff will review the plans, specifications, inspection programs, and QA/QC programs to assure that adequate measures are being taken to construct the design features according to accepted er:gineering practices. The staff will compare the information provided with typical programs used in the i construction industry. NUREG-1623 contains examples of acceptable specifications and testing programs that were approved by the staff and actually applied at several sites.
l 3.4.3 Acceptance Criteria In general, designs that conform to the suggested criteria in NUREG-1623 will be found acceptable.
NUREG-1623 discusses acceptable methods for designing erosion protection to provide reasonable assurance ol' effective long-term control and to meet NRC requirements. This document also provides discussions tmd technical bases for use of specific criteria to meet the 1000-year longevity requirement, without the t se of active maintenance. Acceptable design methods are presented, and reasonable similarity 6 the design to these methods forms the primary basis for staff review of erosion protection 3 desig .s. These criteria were derived from regulatory requirements, other regulatory guidance, staff exrerience, and various technical references. NUREG-1623 updates and expands the FSTP (NRC, 1990).
If active maintenance is proposed as an alternative to the designs suggested above, such an approach will i be found acceptable if the following criteria are met: j (1) The maintenance approach must achieve an equivalent level of stabilization and containment and protection of public health, safety, and the environment; (2) The licensee must demonstrate a site specific need for the use of active maintenance and an economic benefit; and (3) The licensee must provide funding for the maintenance by increasing the amount of the required surety. The licensee should also work 'vith the long-term custodian to assess any additional funding requirements related to long-term surveillance and monitoring. )
(
3.4.4 Evaluation Findings i i
If ti3e staff's evaluation of hydrologic and hydraulic engineering aspects of the RP confirms that the j erosior protection designs are acceptable, the following conclusions may be presented in the TER. i l
The staff has completed its review of the information provided to assess the design of erosion protection i NUREG-1620 3-12 o
.l at the site. This review included an evaluation using the review procedures in SRP Section 3.4.2 and acceptance criteria outlined in SRP Section 3.4.3. On the basis of its review, the staff concludes that the erosion protection designs are acceptable.
The mill tailings will be protected from flooding and erosion by an engineered rock riprap layer. The riprap has been designed in accordance with the guidance suggested by the NRC staff. The staff i
considers that erosion protection that meets that guidance will provide adequate protection against erosion and dispersion by natural forces over the long term. In addition to the adequacy of the flood analyses discussed in SRP Sections 3.2 and 3.3, the staff concludes that adequate erosion protection
! designs are provided by (1) use of appropnate methods for determining erosion protection needed to resist the forces produced by the design discharge, and (2) selection of a rock type for the riprap layer that will be durable and capable of providing the necessary erosion protection for a long period of time.
Further, the staff considers that the riprap layers proposed will be durable over the 1,004 year design life, for the following reasons: (1) the rock proposed for the riprap layers was evaluated using rock quality procedures suggested by the staff and is not expected to deteriorate significantly over the 1,004 year design life; (2) the rock fragments are dense, sound resistant to abrasion, and free from cracks, seams, and other defects; and (3) during constmetion, the rock layers will be placed in accordance with appropriate engineering and testing practices, minimizing the potential for damage, dispersion, and segregation of the rock.
The riprap for the relatively flat top and side slopes is designed to be sufficiently large to minimize erosion potential. The rock will be capable of resisting flooding and erosion, depending on the slope selected. Thus, the staff concludes that the relatively steep slopes, with their corresponding rock designs, are acceptable.
On the basis of its review of the designs for the site, the staff concludes that the hydraulic designs contribute to meeting the tequirements of 10 CFR Part 40 Appendix A: (1) Criterion 1, requiring that erosion, disturbance, and dispersion by natural forces over the long temt are minimized and that the tailings am disposed of in a manner that does not require actis e maintenance to preserve conditions of the site; (2) Criterion 4(c), requiring embankments and cover slopes to be relatively flat after stabilization to minimize crosion potential and to provide conservative factors of safety that ensure long-term stability; (3) Criterion 4(d), requiring that the rock cover reduces wind and water erosion to negligible ' levels, including consideration of such factors as the shape, size, composition, and gradation of the rock particles; (4) Criterion 6(1), requiring the design to be effective for 200-1,000 years; and (5)
Criterion 12, requiring that active on-going maintenance is not necessary to preserve isolation.
3,4.5 References Nuclear Regulatory Commission,1990. " Design of Erosion Protection Covers for Stabilization of Uranium Mill Tailings Sites." Final Staff Technical Position.
Nuclear Regulatory Commission,1998. * " Design of Erosion Protection for Long-Term Stabilization." Draft NUREG-1623.
- NUREG-1623 updates the FSTP, based on experience gained in the Title 1 and Title II programs and on additional research in the area of erosion protection design. Specific references related to design, analysis, and information needs for the RP are discussed in these documents. A general reference list is 3-13 NUREG-1620
Provided in SRP Section 3.6.
l I
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l NUREG-1620 3-14
3.5 DESIGN OF UNPROTECTED SOIL COVERS AND VEGETATIVE SOIL COVERS 3.5.1 Areas of Review If an unprotected soil cover or a vegetative soil cover is proposed, the following design details, calculations, and analyses will be reviewed:
(1) Determination of allowable shear stresses and permissible velocities for the cover, (2) Determination of allowable shear stresses and permissible velocities for the cover in a degraded state, including the effects of fires, droughts, vegetation succession, and other impacts to the ability of the cover to function without maintenance; (3) Information on types of vegetation proposed and their abilities to survive natural phenomena; and
-(4) Information, analyses, and calculations of all input parameters to models used.
3.5.2 Review Procedures i
If a soil cover is proposed, the staff will evaluate the design using the general criteria outlined in NUREG-1623 (NRC,1998). Particular attention will be given to the input parameters to various models.
(1) The staff will verify that the design flow rate includes an appropriate flow concentration factor l that reflects consideration of settlement, soil removal by sheet flow and wind, degradation of the I vegetation cover, intmsion of trees, blockage of flows by fallen trees, etc.
(2) The staff will verify that estimates of Manning's "n" value correspond to the vegetation cover proposed and are proper for estimating allowable shear stresses and permissible velocities.
(3)' The staff will verify that appropriate values of allowable shear stresses and permissible velocities have been used and conservatively reflect potential changes that could occur to the cover over a long period of time as a result of fires, droughts, diseases, vegetation succession, or general cover degradation.
(4) The staff will check analyses and/or independently calculate allowable slopes using several l different methods and ranges of input parameters. Using a range of flow concentration factors, shear stresses, permissible velocities, "n" values, and models, the staff will check the sensitivity of the analyses and will verify that reasonable and appropriate values ofinput parameters have been selected.
If a sacrificial soil cover is proposed to meet the minimum 200-year stability requirement, the staff will check the calculations and justification for reduction of the stability period using procedures given in NUREG-1623.
l 3-15 NUREG-1620
i . .
1 3.5.3 Acceptance Criteria In general, designs that conform to the suggested criteria in NUREG-1623 will be found acceptable.
NUREG-1623 discusses acceptable methods for designing erosion protection to provide reasonable j assurance of effective long-tenn control and thus meet NRC requirements. This document also provides discussions and technical bases for use of specific criteria to meet the 1,000-year longevity requirement, without the use of active maintenance. Specific acceptance criteria for many of the review areas are presented and form the primary basis for staff review of erosion protection designs. These criteria were derived from regulatory requirements, other regulatory guidance, staff experience, and various technical l references.
i If active maintenance is proposed as an alternative to the designs suggested above, such an approach will be found acceptable if the following criteria are met:
(1) De maintenance approach must achieve an equivalent level of stabilization and containment and protection of public health, safety, and the environment; (2) De licensee must demonstrate a site specific need for the use of active maintenance and an economic benefit; and (3) The licensee must provide funding for the maintenance by increasing the amount of the required surety. The licensee should also work with the long-term custodian to assess any additional funding requirements related to long-term surveillance and monitoring.
3.5.4 Evaluation Findings If the staff's evaluation of hydrologic and hydraulic engineering aspects of the reclamation plan confirms that the cover designs are acceptable, the following conclusions may be presented in the TER.
The staff has completed its review of the information provided to assess the design of erosion protection covers at the site. This review included an evaluation using the review procedures in SRP Section 3.5.2 and acceptance criteria outlined in SRP Section 3.5.3. On the basis of its review, the staff concludes that the designs are acceptable and meet the requirements of 10 CFR Part 40, Appendix A.
De mill tailings will be protected from flooding and erosion by an engineered soil cover. The cover has been designed in accordance with the guidance suggested by the staff. The staff considers that a soil cover that meets that guidance will provide adequate protection against erosion and dispersion by natural 3 forces over the long term. In addition to the adequacy of the flood analyses discussed in SRP Sections 3.2 and 3.3, the staff concludes that adequate cover designs are provided by (1) use of appropriate methods for determining cover slopes needed to resist the forces produced by the design discharge, and (2) selection of a cover that will be capable of providing the necessary erosion protection for a long 1 period of time.
De relatively flat top and side slopes of the cover are designed to provide long-term stability. The erosion potential of the cover is minimized by designing slopes that are sufficiently flat to minimize velocities and to resist flooding and erosion. Thus, the staff concludes that the cover slopes are i l
3-16 k
't i acceptable.
On the basis of a a review of the designs for the site, the staff concludes rnat the cover designs contribute to meeting the requirements of 10 CFR Part 40, Appendix A: (1) Criterion 1, requiring that erosion, disturbance, and dispersion by natural forces over the long term are minimized and that the tailings are disposed ofin a manner that does not require active maintenance to preserve conditions of the site; (2) Criterion 4(c), requi:ing that embankments and cover slopes are relatively flat after stabilization to minimize erosion potential and to provide conservative factors of safety; (3) Criterion 6(1), requiring the design to be effective for 200 to 1,000 years; and (4) Criterion 12, requiring that active ongoing maintenance is not necessary to preserve isolation.
3.5.5 References Nuclear Regulatory Commission,1990. " Design of Erosion Protection Covers for Stabilization of Uranium Mill Tailings Sites," Final Staff Technical Position.
Nuclear Regulatory Commission,1998. *" Design of Erosion Protection forlong-Term Stabilization," Draft NUREG-1623, 3.6 General References American Nuclear Society, "American National Standard for Determining Design Basis Flooding at Power Reactor Sites," ANSI /ANS-2.8,1981.
Chow, V. T., Open Channel Hydraulics, McGraw-Hill Book Co., New York,1959. l Crippen, J.R. and C.D. Bue, " Maximum Floodflows in the Conterminous United States," USGS Water Supply Paper No.1887,1977.
l Fread, D.L., "DAMBRK: The NWS Dam-Break Flood Forecasting Model," National Weather
- Service, Silver Spring, MD, continuously updated.
Henderson, F.M., Open Channel Flow, MacMillan Co., New York,1971.
1
- NUREG-1623 updates the FSTP, based on experience gained in the Title I and Title II programs and on additional research in the area of erosion protection design. Specific references related to design, analysis, and information needs for the R' are discussed in these documents. A general reference list is provided in SRP Section 3.6.
Interagency Advisory Committee on Water Data, Hydrology Subcommittee Working Group on PMF Risk Assessment," Draft Report on the Feasibility of Assigning a Probability to the Probable Maximum Flood," June 1985.
3-17 NUREG-1620
Nelson, J.D., gLal., " Design Considerations for Long-Term Stabilization of Uranium Mill Tailings Impoundments," NUREG/CR-3397, ORNL-5979. October 1983.
! I Simons, D.B; and Senturk, F., Sediment Transpod Technology, Water Resources Publications, Fort Collins, Colorado,1977.
Stephenson, D , Rockfill Hydraulic Engineering Developments in Geotechnical Engineering No.
, - 27. Elsevier Scientific Publishing Company,1979.
l L Temple, D.M., gla[., " Stability Design of Grass-Lined Open Channels," U.S. Department of l Agriculture, Agricultural Handbook Number 667,1987.
i
- U. S. Army Corps of Engineers, " Flood Hydrograph Package," HEC-1, Hydrologic Engineering ,
Center, continuously updated.
. U.S. Army Corps of Engineers," Water Surface Profiles," HEC-2, Hydrologic Engineering l Center, Davis, California, continuously updated.
l . U.S. Army Corps of Engmeers, " Reservoir System Operation for Flood Control," HEC-5, l Hydrologic Engineering Center, Davis, Califomia.
I U.S. Army Corps of Engineers " Stone Protection," CE 1308, January 1948.
U.S. Army Corps of Engineers, " Standard Project Flood Determinations," EM1110-2-1411,26
- March 1952 (rev. March 1%5).
U.S. Anny Corps of Engineers, " Flood Hydrograph Analysis and Computations," EM1110 1405,31 August 1959.
U.S. Army Corps of Engineers, " Backwater Curves in River Channels," EMI110-2-1409, 7 December 1959.
U.S. Army Corps of Engineers, " Routing of Floods through River Channels," EMI110-2-1408, 1 March 1960.
U.S. Army Corps of Engineers, " Hydraulic Design Criteria," continuously updated and revised. l U.S. Army Corps of Engineers, " Hydraulic Design of Spillways," EM1110-2-1603,31 March !
I 1965.
U.S. Army Corps of Engineers, " Interior Dramage of Leveed Urban Areas: Hydrology,"
! . EM1110-2-1410,3 May 1965. ,
l l U.S. Army Corps of Engineers, " Policies and Procedures Pertaining to Determination of 'I L
l Spillway Capacities and Freeboard Allowances for Dams," EC1110-2-27, February 1968. l l
NUREG-1620 3-18 i
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.l l U.S. Army Corps of Engineers, " Hydraulic Design of Flood Control Channels," EMI110-1601, 1 July 1970.
U.S. Army Corps of Engineers, " Additional Guidance for Riprap Channel Protection, "ETL1110-2-120, May 1971.
U.S. Army Corps of Engineers, " Runoff from Snowmelt," EM1110-2-1406,5 January 1980.
U. S. Bureau of Reclamation, Desien of Small Dams. Second Edition, U.S. Department of the Interior,1973.
U. S. Bureau of Reclamatior . "Cornparison of Estimated Maximum Flood Peaks with Historic Floods," 1986.
I Nuclear Regulatory Commission,1990. " Design of Erosion Protection Covers for Stabilization l of Uranium Mill Tailings Sites." Final Staff Technical Position.
Nuclear Regulatory Commissica, " Design Basis Floods for Nuclear Power Plants," Regulatory Guide 1.59.
Nuclear Regulatory Commission, Standard Format and Content for Documentation of Remedial Action Selection at Title 1 Uranium Mill Tailings Sites," February 1989.
U.S. Weather Bureau, Hydrometeorological Reports (now U.S. Weather Service, NOAA),
Hydrometeorological Branch: Nos. 43,49,55, i
a l
{
1 3-19 NUREG-1620 i
,l l 4.0 WATER RESOURCES PROTECTION Protection of water resources is a process that encompasses two distinct strategies. The first strategy is to prevent the spread of contaminants from disposal and processing sites into ground water or surface water. This strategy requires the staff to ensure that operations and decommissioning are conducted in such a manner as to minimize threats to ground water.
The second strategy is to mitigate the threat to public health from contaminants that have already been mobilized-particularly through ground-water pathways before decommissioning activities. This strategy applies only to those sites where ground-water contamination already exists and requires staff to review existing or proposed ground-water restoration activities to ensure that they will result in compliance with regulatory requirements.
Use of this SRP Chapter 4 chapter should be tailo.2 d to the specific situation and phase of operation at each site. Selection and emphasis of the various aspects of the areas covered by this SRP chapter will be made by the reviewer. The judgment on the areas to be givcn attention during the review is to be based on the specific licensee submittal being reviewed, an inspection of the material presented, prior knowledge of the site and its operating history, and whether items of special safety significance are involved.
This chapter presents a standard approach for reviewing, evaluating, and documenting the evaluation findings for issues pertaining to water resource protection during the various phases of the license termination process at licensed uranium mill sites. Review of water resources protecdon informatioin shall be coordinated with the evaluation of the site stratigraphy, structural and tectonic information and surface water and erosion protection information as discribed in chapters 1 and 3, respectively. Review procedures in this chapter pertain to the following two types of documents that are submitted for review by the staff during the license termination process:
(1) RPs are submitted by the licensee to obtain approval of surface reclamation and decontamination work, including stabilization of mill tailings, and elimination (or isolation) of present or potential contaminant sources.
(2) Corrective Action Plans are submitted by the licensee to obtain approval of ground-water restoration strategies at sites where ground-water contamination has been detected.
(3) Ground-water Completion Reports are submitted by the licensee to confirm that the ground-water quality will remain stable after ground-water restoration strategies have been implemented and that ground-water protection standards have been correctly established.
(4) Long-Term Surveillance Plans are submitted by the long-term custodian to describe the monitoring activities that will be implemented by the custodian.
The ultimate objective of the review is to determine if the proposed RPs and Corrective Action Planwill result in long-term compliance with Part 40, Appendix A. As stated in Part 40, Criterion 5, " Cdreria SA-SD and new Criterion 13 incorporate the basic ground-waterprotection standards imposed by the Environmental Protection Agency in 40 CFR, Part 192, Subparts D and E (48 FR 45926; October 7,1983) which apply during operations andprior to the end ofclosure. Ground-water 4-1 NUREG-1620
F monitoring to comply wi:h these standards is required by Criterion 7A." To meet this regulatory objective, the following issues must be evaluated: )
(1) . Site characterization; (2) Ground-water protection standards; (3). Hazard and as low as is reasonably achievable (ALARA) assessment for altemate concentration limits (ACLs), as defined by Part 40, Appendix A, Criteria 5B(5) and SB(6); and (4) Ground-water corrective action and monitoring plans.
Accordingly, this chapter contains a section for each of these issues. Discussions of the establishing and review of ACLs in this section of the SRP supercedes but do not replace, the existing Technical Position (TP) on ACLs (NRC,1996). The licensee is encouraged to follow the format and content for an ACL application presented in the TP.
4.1 SITE CHARACTERIZATION j I
4.1.1 Areas of Review -
The staff shall review the characterization information, given the circumstances and life cycle of a particular site, and the nature of the document under review (RP, Corrective Action Plan). The staff shall )
also evaluate regional and site-specific hydrologic information related to both the former processing site
]
and the proposed disposal site if they are different. The hydrologic infonnation shall include both surface-water and ground-water systems, along with any interrelations among those systems. Complete
- site characterization should include or reference the following.
(1) Site background data that include descriptions of:
1 (a) The site history of mining and/or milling operations; (b) Surrounding land and water uses; and )
(c) Site meteorological data.
(2) Ground-water and surface-water hydrology data,includog:
(a) Descriptions of hydrogeology and ground-wat tr conditions; !
(b) Estimation of hydraulic and transport properties for each hydrogeologic unit; (c). Descriptions of surface-water hydrology and estimations of ground-water and surface-waterinteractions; and (d): Assessment of potential for flooding and erosion.
i NUREG-1620 4-2 l
l
)
.l (3) Information concerning geochemical conditions and water quality, including :
(a) Identification of constituents of concern; (b) Determination of background ground-water quality; (c) Confirmation of proper statistical analysis; (d) Delineation of the nature and extent of contaminaticn; (e) Identification of contaminant source terms; (f) Characterization of subsurface geochemical properties; and (g) Identification of attenuation mechanisms and estimation of attenuation rates.
(4) Human health and environmental risk evaluations.
4.1.2 Review Procedures The level of effort necessary to adequately characterize a particular site depends on site-specific circumstances. For example, if a particular site has no ground-water contamination and tailings are disposed of off site, there will be very little need for detailed site characterization in suppon of water resources pro:ection. Conversely, at a site with an existing source of ground-water contamination, the site characterization must be sufficient to support selection of restoration strategies and to determine the level of risk to human health and the environment.
Because the apprcpriate level of site characteriz tion is specific to the methods of tailings disposal a-d ground-water corrective action selected for a particular site, there is not a single acceptable approach to conducting a site characterization. As such, the reviewer shall (1) Thoroughly evaluate the characterization information using the acceptance criteria in SRP Section 4.1.3, but reserve finaljudgment until all sections of the application have been reviewed; and l
(2) Assess whether the level of detail and technical merit of the characterization are sufficient to support the proposals, assumptions, and assertions in the application that are used to demonstrate regulatory compliance.
4.1.3 Acceptance Criteria Knowledge c' the site is needed to evaluate the existing and potential contamination. This characterization information shall include a description of activities and physical properties that may affect water resources at the mill site. The site characterization will be acceptable if it meets the following criteria:
4-3 NUREG-1620
(1) It contains a description of the site that is sufficient to assess the environmental impact the former mill site may have on the surrounding area; the populations that may be affected by such impacts; and meteorological conditions that may act to transport contaminants offsite. An acceptable site description will contain the following specific information:
(a) A site history that includes:
(i) A list of the known leaching solutions and other chemicals used in the milling process and their relative quantities in mill wastes. The list should also identify any other hazardous wastes listed in 10 CFR Part 40, Appendix A, that may have been disposed of in the tailings pile.
(ii) A description of the wastes generated at the site during milling operations, waste discharge locations, types of retaining structures used (e.g., tailings piles, ponds, landfills), quantities of waste generated, and a chronology of waste management practices.
(iii) A summary of the known impacts of the site activities on the hydrologic system and background water quality.
(iv) If applicable, descriptions of any human activities or natural processes unrelated to the milling operation that may have altered the hydrogeologic system. Such human activities include ground-water use, crop irrigation, mine dewatering, ore storage, municipal waste land filling, oil and gas development, or exploratory drilling. Natural processes include geothermal springs, natural concentration of soluble salts by evaporation, erosion processes, and ground-water / surface-water interactions.
(b) Information pertaining to surrounding land and water uses that includes:
(i) A general overview of water uses, locationi, quantities of water available, and the potential uses to which quality of water is suited; (ii) Definitions of the class-of-use category for each water source (e.g., drinking water, agricultural, livestock, limited use);
(iii) Identification of potential receptors of present or future ground-water or j
surface-water contamination; ed (iv) Descriptions of non-mill-related human activities or natural processes that may affect water quality or water uses (e.g., oil and gas development, municipal waste landfills, crop irrigation, drought, erosion, etc.).
Human water consumption is not the only water use that must be considered in the review. Any use that may bring someone into contact with the contaminated water must be considered when evaluating health hazards. For example, nonpotable, radon-contaminated water piped to a public lavatory could pose a substantial health hazard.
NUREG-1620 4-4
l (c) Sufficient ineteorologic data for the region, including rainfall and evaporation data in sufficient detail to assess projected water infiltration through the disposal cel!.
l Monthly averages are an acceptable means of presenting general meteorological conditions; however, the reviewer shall ensure that extreme weather conditions are adequately described. )
(2) The ground-water and surface-water hydrology is described adequately to support modeling l predictions of likely contaminant migration paths; selection of monitor well locations; and, when ground-water contamination exists, selection of a restoration strategy. The following specific information is provided to support these objectives: )
(a) A description of hydrogeologic units that may affect transport of contaminants away from the site via ground-water pathways.
1 (i) Hydrostratigraphic cross-sections and maps are included to delineate the j geometry, lateral extent, thickness, and rock or sediment type of all potentially affected aquifers and confining zones beneath the processing and disposal sites. Data used to construct such maps are referenced and of adequate quality and quantity to suppon a technically defensible interpretation.
1 (ii) The hydrogeologic units that constitute the uppermost aquifer (where regulatory compliance will be evaluated) are identified. The uppermost aquifer is the geologic formation nearest the natural ground surface that is an aquifer, as well as lower aquifers that are hydraulically interconnected with this aquifer within the facility's property boundary.
(iii) If local perched aquifers are found at the site, their presence is noted. These formations may cause contaminated water to be divened around monitoring systems, or may be improperly interpreted as the uppermost aquifer. Any saturated zone created by uranium or thorium recovery operations we 'Jd not be considered an aquifer unless the zone is or potentially is: (1) hydraulically interconnected to a natural aquifer; (2) capable of discaarge to surface water; or (3) reasonably accessible because of migration beyond the venical projection of the boundary, of the land transferred for long-term l govemment ownership and care in accordance with Pan 40, Appendix A, Criterion 11.
(iv) Unsaturated zones, through which hazardous constituents are conveyed to the water-bearing units, are described. This information is adequate to suppon the assumptions used in estimating the source term for contaminant transport pathways. This information includes identification of potential preferential flow pathways that are either natural (e.g., buried stream channels), or man-made (e.g., abandoned wells or mine shafts).
4-5 NUREG-1620
F !
< (v) Infonnation on geologic characteristics that may affect ground-water flow beneath the former mill site is provided. Examples of pertinent geologic characteristics include identification of significant faulting in the area, fracture and joint orientation and spacing for the underlying bedrock, and geomorphology of soil and sedimentary deposits (e.g., fluvial, glacial, or volcanic deposits).
(vi) Hydraulic-head contour maps, of both local and regional scale, for the uppermost aquifer and any units connected hydraulically beneath the site are sufficient to determine hydraulic gradients, ground-water flow direction, i and proximity to offsite ground-water users. These maps are based on static i water level observations at onsite and regional wells. Several measurements are taken at each observation well. These measurements are sufficiently l
spaced in time to capture water level fluctuations caused by seasonal
- changes or local pumping of ground water. Enough observation wells are I
sampled to produce an adequate water elevation contour map. The appropriate number of wells is dependent on the size of the site and the L choice of contour interval. However, as a rough estimate, there is at least i I
one observation well for each contour line on the map. A more detailed j contour map (small contour interval) is produced for the site and I surrounding propenies. m level of detail used for the regional contour map may be limited by the number of observation wells available offsite. The reviewer shall bear in mind that calculations of hydraulic gradients from l l hydraulic head contour maps is only rigorously valid for horizontal flow in {
aquifers. j (b) Estimations of hydraulic and transpon propenies of the underlying aquifer.
Hydrogeologic parameters used to support the choice of a ground-water restoration strategy or to demonstrate compliance include hydraulic conductivity, saturated thickness of hydrogeologic units, hydraulic gradient, effective porosity, storage coefficient, and dispersivity. The reviewer shall consider the influence of each of these parameters on evaluating compliance with standards established pursuant to Part 40, Appendix A, and determine j whether estimates for each parameter are reasonably cesservative, based on the ,
data provided. !
(i) Hydraulic conductivity and storage coefficients are determined by conducting aquifer pump tests on several wells at the site. Pump test methods that are consistent with ASTM standards for the measurement of geotechnical propenies and for ~1uifer hydraulic tests are considered acceptable by the NRC. 'Ihese ASTM standards include D 4044-92, D 4050-
- 91. D 4104-91, D 4105-91, D 4106-91, D 4630-86, D 5269-92, D 5270-92, D 5472-93, and D 5473-93. Any other peer-reviewed method or commonly accepted practice for aquifer parameter estimation may be used. When curve fitting is used to analyze pump test data, deviations of observation data from ideal curves are explained in tenns of likely causes (e.g.,
NUREG-1620 4-6
- s. l impermeable or recharge boundaries, leaky aquitards, or heterogeneities).
When average hydraulic parameters are reported, the reviewer shall consider that many hydrogeologic parameters, including hydraulic conductivity, typically exhibit a log-normal distribution. Consequently, the geometric mean may be more representative of the overall conditions within a unit than the arithmetic mean.
(ii) Horizontal components of hydraulic gradient are estimated by measurement of the distance between contour intervals on hydraulic head contour maps.
Vertical components of hydraulic gradient are estimated from head measurements in different aquifers.
(iii) Generally, analyses considering steady state conditions are acceptable unless site conditions indicate otherwise. If transient conditions are modeled, storage coefficients estimated from standard tests indicated in (i) above are used.
(iv) If contaminant transport is modeled, then longitudinal and transverse dispersivity values are either obtained from a tracer test or conservative l values based on published literature are used. Because dispersivities depend l on the size of the modeled region, the reviewer shall carefully compare the l values for dispersivity used in the licensee's transport modeling with those values cited in survey studies such as Gelhar et al. (1992), and verify that they represent conservative estimates for the site.
(c) Estimation of ground-water / surface-water interactions at sites with nearby streams, rivers, or lakes.
. The location of smface-water bodies that are connected to the site ground-water flow system are identified. Surface-water elevations shall be used to help describe the site ground-water flow system if a stream or other surface-water body discharges into or drains the site ground-water flow system. Another acceptable approach is to evaluate hydraulic head contour based on data from monitor wells in the vicinity of streams. ;
(3) Geochemical conditions and water quality are characterized sufficiently to: l 1
(a) Identify the constituents of concem.
Any chemical constituent that meets both of the following criteria must be listed as a constituent of concern:
(i) The constituent is reasonably expected to be in or derived from the tailings. ,
(ii) The constituent is listed in either Part 40, Appendix A, " Hazardous i Constituent," Criterion 13, or it has been identified in a specific condition in the license.
4-7 NUREG-1620
Table 4.1.3-1 provides a list of constituents commonly associated with uranium mill tailings (Smith,1987). This list is based on a chemical survey performed by staff at 17 Title II sites.
Table 4.1.3-1. Common Uranium Mill Chemical Constituents Inorganic Constituents Organic Constituents Arsenic Carbon Disulfide Barium Chloroform Beryllium Diethyl Phthalate Cadmium 2-Butanone Chromium 1.2-Dichloroethane Cyanide Naphthalene Lead Mercury Mo'.ybdenum Net Gross Alpha Nickel Radium-226 and -228 Selenium Silver Thorium-230 Uranium Most of the constituents in Part 40, Appendix A, Criterion 13 are organic compounds that are not normally associated with uranium milling processes. The expected presence of organic compounds is assessed from knowledge of the chemicals used during the milling process or other materials that may have been disposed ofin the tailings. If there is no record of organic compounds used in the process, screening tests for volatile and semivolatile organics are performed to confirm the absence of organic compounds in the tailings and ground water.
Staff may request that licensees add constituents to the list of constituents of concem that are not included in Part 40, Appendix A, Criterion 13. If ammonia or nitrate was used in the milling process, ammonia and nitrate should be added to the list of constituents. Other constituents should be added to the list, if the - j reviewer finds a significant health and safety or environmental concem about -i those constituents. Before requiring additional constituents it should be considered if such constituents are covered by on State ground-water programs.
NUREG-1620 4-8 i
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l In identifying additional constituents, the staff should ensure that any additions are made based ona' sound technical and regulatory basis. Examples of sound technical bases include the following:
(a) NRC and the EPA agree to use one Federal contact with a licensee, which is NRC. This approach requires NRC to include some constituents, in its licenses, that are not normally licensed by the NRC.
(b) Trends in ground-water contamination show that after several years of decreases in the level of contamination, the level of contammation is beginning to rise again.
L (c) Surrogate parameters that cover a family of constituents show an increase in the concentration in ground water. Therefore, the staff may require licensees to monitor for all constituents found in that family.
(d) Some constituents used in the milling process, but not listed in Criteria 13, such as ammonia and nitrate need to be covered.
Constituents should not be added just because an individual State regulatory
! body is concemed about that constituent. In identifying constituents of regulatory concem not covered in Criterion 13, the reviewer must ensure that an l
l individual State does not use the NRC to implement the ground-water programs that are the responsibility of the State. Having a State identify a constituent as one of concem to the state is not necessarily a proper basis for NRC to include that constituent.
f Even if the criteria for identifying a hazardous constituen't are met, NRC may still decide to exclude certain constituents on a site-specific basis if it can be shown that the constituents are not capable of posing a substantial present or potential hazard to human health or the environment. In considering such exclusions, the reviewer must consider potential adverse effects on ground water and hydraulically connected surface-water quality. NRC may decide to exclude a constituent if the dissolved concentration of the constituent in the t
tailing fluids is equal to orless than the concentration of that constituent in the i
background water quality. Altematively, NRC may decide to exclude a ;
constituent if the dissolved concentration of the constituent in the tailing fluids i is equal to or less than the maximum value for ground-water protection listed in Part 40, Appendix A, Table SC.
New constituents should be added in a timely manner. This is either at the time the Corrective Action Plan is accepted for review, or at sometime during the
. lifetime of the Corrective Action Plan. New constituents will not be required at the time of the license-termint. tion monitoring submittal. l i
l l
4-9 NUREG-1620 l l
T .
(b) Provide a determination of background (baseline) water quality.
Bwkground water quality is defined as the chemical quality of water that would be expected at a site if contamination had not occurred from the uranium milling operation. At most mill sites, the background water quality will be the primary ground-water protection standard.
Water quality data available from studies conducted in conjunction with initial licensing for operation of the facility are used to establish the background. If hazardous constituents identified by NRC were not sampled in the original background monitoring program, the licensee should have conducted additional sampling to establish background levels. When adequate Mte-specific baseline data cannot be obtaiaed for identified constituents of concern, samples of adjacent, and up-gradient, uncontaminated, water are taken as proxies to onsite baseline samples.
To determine acceptability of background water quality determination, the following information is provided:
(i) Maps are of sufficient wtail and legibility to show the background monitoring locations.
(ii) Descriptions of sampling methods, monitoring devices, and quality assurance (QA) practices are provided. Examples of acceptable methods include those that are consistent with ASTM Standards D 4448 for monitor well sampling, D 46% for unsaturated zone sampling, and D 4840 for chain-of-custody procedures. Other methods, if used, are properly referenced and justified.
(iii) When they exist, zones of differing background water quality are delineated.
A discussion of the possible causes of these differing water quality zones is included (e.g., changes from geochemically oxidizing to reducing zones in the aquifer; changes in rock type across a fault boundary).
(iv) A table for each zone of distinct water quality, listing summary statistics (i.e., mean, standard deviation, and number of samples) for baseline water quality sampling for each constituent of concern, is provided.
(v) A preoperational monitoring program has been in place for one year consistent with the requirements of Part 40, Appendix A, Criteria 7.
Samples are taken at least monthly under this program.
Alternatively, background water quality may already be defined by a condition in the license. If this is the case, background limits for a ground-water protection standard have already been identified, and the reviewer should rely on those along with any constituents and standards listed in Criteria 5(c) as the regulatory limits applicable to this site.
NUREG-1620 4-10
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(c) Confirm the proper use of statistical techniques for assessing water quality.
Statistical hypothesis testing methods used for: (i) establishing background 4 water quality; (ii) establishing ground-water protection standards for compliance monitoring;(iii) detennining the extent of ground-water contamination; and (iv) establishing the ground-water cleanup goals, are described in Appendix B.
(d) Define the extent of contamination.
For each hazardous constituent the licensee detennines the extent of contamination in ground water at the site. Ground-water contamination at uranium mill sites is usually limited to the uppermost aquifer. Maps showing the locations of sampling wells should be included, along with a discussion of sampling practices. The most useful way to present thic information is on a map showing concentration contours for each hazardous constituent and water surface elevation contours. In this manner, the size, shape, sou-ce, and direction l of movement can be readily examined by the reviewer. Sampling techniques suitable for characterizing the extent of ground-water contamination are l discussed in SRP Section 4.1.3(3)(c). >
- I l
l The extent of contamination is delineated in three dimensions. This typically involves drilling a number of characterization wells and determining v'hether the j water quality in each of these wells meets background w ~ ater quality (i.e., null
- hypothesis) or whether the ground water is contaminated (i.e., altemative
! hypothesis). It may not be necessary to sample all hazardous constituents, to delineate the extent of contamination. Two or three indicator parameters (e.g.,
total dissolved solids, and chloride) might be selected. These indicators should !
be conservative--meaning that they are neither reactive, nor are they easily sorbed to soil -so that they provide a good indication of the maximum extent of !'
contamination.
The transition from contaminated to uncontaminated ground water is often ;
gradual. Thus, difficulty arises in determining where the contaminated water i 1
ends and the background water begins. The background sample data provide the easiest means for comparison of characterization well measurements to background measurements for the indicator parameters. The easiest method is to j use the tolerance limit method to determine the upper limit for the range of l background concentrations; characterization wells with concentrations above this limit can be assumed to have been affected by ground-water contamination. i I
Use of the tolerance limit method is discussed in SRP Section 4.2.3(3)(a).
Complications in delineating the extent of contammation arise at sites that have zones of differing water quality, or where on-site background water q ulity is not properly determined before discovery of ground-water contamination.
Where zones of differing water quality are present, the teviewer shall verify that characterization wells are compared with the background sample from the 4-11 NUREG-1620 l
appropriate water quality zone. Where on-site background water quality has not !
been properly determined, then up gradient or offsite samples are obtained, as ;
discussed in SRP Section 4.1.3(3)(c).
The reviewer shall verify that the licensee has provided the following information to support determining the extent of contamination.
(i) A map or maps showing the distribution of surface wastes and contaminated materials at and near the site.
(ii) A map or maps showing the approximate shape and extent of ground-water contamination (e.g., concentration contour maps for indicator parameters in ground water).
1 (iii) Identification of any off-site sources of water contamination or other factors that may have a bearing on observed water quality.
(e) Properly estimate We source term.
Existing sources of ground-water contamination are defined in terms of location and rate of entry into the subsurface. At some sites, the contaminant sources have been effectively eliminated through stabilization or removal of tailings piles. However, residual sources may still exist in contammated subsurface soils at the site. For ground-water contamination that originates from an onsite tailings pile, the source term is determined based on the chemical properties of the leachate and the rate at which leachate is released from the disposal area. The level of review given to source term calculations is commensurate with the overall importance of source term estimations to the selection of the restoration strategy.
(i) Source terms are reasonably correlated to the history of ore processing. All facilities from which leakage can occur are identified. Leaking constituents are identified based on the nature of the processing fluids. The volume of leakage is estimated in a realistic yet conservative manner. This can be done using water balance calculations, infiltration modeling, or seepage monitoring approaches.
(ii) When geochemical models are used to predict the fate and transport of existing contamination where the original source has been eliminated, the distribution of each hazardous constituent in place is taken as the source term.
(f) Characterize the subsurface geochemical propenies.
To effectively model the fate and transport of contaminants in ground water, it is important to characterize the geochemical propenies of the natural waters and the aquifer mineralogy. Characterization of the underlying lithologies includes NUREG-1620 4-12
-l .:
4 l measurements of buffering capacity, total organic carbon, cation exchange capacity, and identification of the clay mineralogy. The general chemical characteristics of fluids within the lithologies are described by measurements of pH, temperature, dissolved oxygen, redox potential (Eh), buffering capacity, and the concentrations of major ions and trace metals.
'(i) Aquifer geochemistry is adequate to model the attenuation of contaminants.
The values of the geochemical parameters used in transport models are ,
justified. Acceptable parameter estimation methods include, direct measurement, use of a conservative bounding estimate, reference to literature values for similar aquifer conditions, and laboratory studies of
. aquifer materials.
1 (g) Identify contaminant attenuation mechanisms.
L The major attenuation mechanisms that work to mitigate the effects of ground-water contamination are dilution in surrounding ground water, sorption of contaminants to the soil matrix, and immobilization of contaminants due from geochemical and biochemical reactions.
(i) Claims that contamination is reduced by dilution are supported by a sufficient technical basis. There are two mechanisms for dilution of a contammant plume in ground water: dispersion and mixing. Dispersion is a l process whereby contaminant plumes tend to spread out and become less j l
concentrated as they are advected away from the source. Mixing is the result of uncontaminated water being added to the ground-water system through i natural recharge, injection, or upward movement of water from underlying j l aquifers, which reduces the concentration of contammants. Estimation of l surface recharge or upward flow through leaky aquitards is either established from field measurements or conservative assumptions are used. l l
t l (ii) The values of sorption coefficients are based on the nature of the constituent l and site-specific geochemical conditions. The degree of sorption of l contaminants to the soil matrix depends on the affinity of each constituent for the soilin a particular aquifer. Constituents that carry a positive charge,
( as do most trace metals in solution, are good candidates for cation exchange adsorption to clay and oxide surfaces. However, because surface charges of clays and oxides decrease with decreasing pH, the reviewer shall carefully i examine claims of attenuation from cation exchange under low pH ;
l conditions. Organic contaminants tend to be hydrophobic and are strongly ,
attenuated in soils that have high organic carbon content. Most contaminant fate and transport models quantify the affinity of contaminants for soil by use of a distribution coefficient or Ko. Batch or column equilibria experiments, using representative leachate and soil samples, are performed to support estimations of K, for each hazardous constituent.
4-13 NUREG-1620
l (iii) Estimations of attenuation from geochemical or biochemical equilibrium j reactions are accomplished by use of acceptable modeling software l packages such as MINTEQA2 (Allison, et al.,1991) and PHREEQE l (Parkhurst, et al.,1980). However, these packages are limited in that they do not consider transport of contaminants. Thus, results are only valid for l
reactions within a confined space (e.g., within the disposal cell). The reviewer shall determine that all model input parameters have sufficient tect'nical bases and represent reasonably conservative estimations.
Additionally, conclusions drawn from such models are supported by field observation; that is, they are consistent with site characterization data.
(iv) At sites where the contamination source has been effectively eliminated, monitoring data are used to assess attenuation of contaminants. If the contaminant source has been eliminated by surface reclamation, changes in ,
the nature and extent of con *. amination over time are monitored. In such situations the center of mass of the contaminanc plume moves along the direction of ground-water flow. The effects of dispersion are also observable over time as a decrease in peak concentrations near the center of the contaminant plume and a lateral spreading of the plume. If significant precipitation or adsorption is occurring, it is reflected in a decrease in the mass of contaminants in the aqueous phase.
(4) A human health and environmental risk evaluation has been provided.
Risk evaluations are very important to the choice of restoration strategy. However, at sites where the proposed restoration strategy is active remediation to background or maximum concentration levels (MCis), very little risk assessment is necessary because background concentrations pose no excess risk. When performed, risk assessments consider risk to human health and the environment. Risk to human health can be further subdivided into carcinogenic and noncarcinogenic health effects.
(a) Excess carcinogenic risk to human health refers to the increase in the risk of cancer to a hypothetical person exposed to the contamination when compared with the risk that same person would be exposed to from background levels of contamination.
(b) For noncarcinogenic health effects, the risk posed by each contaminant is quantified by a threshold concentration below which no adverse health effects would be expected. Thus, below the respective threshold concentration for each hazardous constituent, the level of risk is considered to be acceptable. These threshold concentrations are conservatively estimated and, for many contammants, are reflected in MCLs established by EPA.
(c) When risk assessments are necessary to demonstrate compliance, the reviewer shall verify that calculations for each hazardous constituent are based on adequately defined locations for the points of exposure (POEs) and c.ontaminant concentrations at the POEs. Additionally, risk is calculated for each hazardous NUREG-1620 4-14
l ,
constnuent from all potential exposure pathways. Typical exposure pathways to be considered are ingestien of drinking water, dermal contact while bathing.
ingestion of produce inigated with contaminated water, and ingestion of fish that inhabit contaminated surface water. Typically, compared to the risk posed by inges: ion of hazardous constituent via drinking water, the other exposure pathways are insignificant. However, this is documented by calculations.
4.1.4 Evaluation Findings If the sti'f's review, as described in SRP Section 4.1, results in the acceptance of the site characterization, the following conclusions may be presented in the TER.
NRC has completed its review of the site characterization at the uranium milling facility. This review included an evaluatian using the review procedures in Section 4.1.2, and the acceptance criteria oatlined in Section 4.1.3.
The licensee has provided an acceptable history of the site, including: (1) a description of leaching solutions and other chemicals used in the process and their relative quantities; (2) a description of the wastes generated at the site during the milling process, and the waste handling facilities; (3) a summary of the known impact of site activities on the hydrologic system and water quality; and (4) a description of non-milling-related activities that may have altered the hydrologic system.
The licensee has p.ovided acceptable information pertaining to the surrounding land and water use including: (1) an overview of water uses, quantity available, and potential uses to which the water is suited;(2) de'initions of the class-of-use category of each water source; (3) identification of potential receptors of ground-water or surfacowater contamination;(4) assessment of variations in dilution effects of stred m flow on contaminants; and (5) assessments of the effects of meteorological conditions on erosion, int'tration, and water-table elevation, i
The licensee has provided acceptable meteorologic data, including : (1) wind speed and direction; (2) ;
rainfall; and (3) evaporation data, to allow an evaluation of potential impacts of the meteorologic conditions on disposal cell performance. .
l The ground-water and surface-water hydrology is acceptably described, including: (1) geometry, lateral extent, and thickness of potentially affected aquifers and confining units; (2) a determination of which l aquifers constitute the uppermost aquifer where regulatory compliance will be evaluated; (3) descriptions l of the unsaturated units that convey hazardous constituents to the water-bearing units; (4) maps of acceptable detail showing the relative dimensions and locations of hydrogeologic units that have been ,
impacted by milling activities; (5) information on geologic characteristics that may affect ground-water l l flow beneath the site; and (6) hydrantic head contour maps of both local and regional scale for the I l uppermost aquifer beneath the site.
The estimation of hyc.caulic and transport properties is acceptable and includes: (1) hydraulic conductivity and storage coefficients determined by conducting aquifer pump tests on several wells; (2) determination of hydraulic gradients using hydraulic head contour maps; (3) calculations of storage coefficients, as applicable; and (4) longitudinal and transverse dispersivities, as appropriate. The 4-15 NUREG-1620
evaluation of ground-water / surface-water interactions with nearby streams, rivers, or lakes is acceptable.
Geochemical conditions and water quality are acceptably analyzed, including identification of constituents of concem that are reasonably expected to be derived from the tailings. Each constituent of concern is found in Part 40, Appendix A, Table SC or Part 40, Appendix A, " Hazardous Constituents,"
Criterion 13, or has been included as a specific condition in the license. Ammonia and nitrate will be included as a constituent in the ground-water monitoring program and clean up program if one is required. The licensee has made an acceptable determination of baseline water quality, including. (1) ,
maps of appropriate scale and legibility; (2) descriptions of sampling methods, monitoring devices, and I QA practices; (3) where applicable, delineation of zones of differing water quality and their possible I origin; and (4) a table of summary statistics for each zone of differing quality. The applicant has provided an acceptable delineation of the extent of contamination supponed by appropriate samples, ,
maps of surface wastes and contaminated materials, maps of the approxiaate shape and extent of ground-water contamination, and identification of any offsite sources of water contamination. The description of the source term is acceptable and includes not only mill tailings constituents but those !
contaminants that might mobilize by contact with tailings leachate. I The characterization of the subsurface geochemical properties is acceptable. Attenuation mechanisms have been described including the technical bases for determining that contamination will be reduced by dilution, sorption on the soil matrix, or geochemical or biochemical reactions. The licensee has provided direct measurements in support of attenuation of contaminants where the source has been eliminated by surface reclamation. 1 The licensee has provided an acceptable human health and environmental risk evaluation that includes carcinogenic and noncarcinogenic health effects. The applicant has identified threshold concentrations below which no adverse health effects would be expected from noncarcinogenic sources. The licensee has used EPA-approved methods to calculate risks to both humans and the environment. The POEs and contaminant concentrations at the POE are based on acmntable assumptions. The licensee has incorporated the risk from all potential exposure pathv .
On the basis of the information provided in the application and the detailed review conducted of the site characterization for the uranium milling facility, the NRC staff has concluded that the information is acceptable and is in compliance with Appendix A, Criterion 5B, which requires the NRC to establish a list of hazardous constituents, concentration limits, a point of compliance (POC), and a compliance period; Part 40, Appendix A, Criterion SC, which provides a table of concentration limbs for cenain constituents when they are present in ground water above background concentrations; Part 40, Appendix A, Criterion SE, which requires licensees conducting ground-water protection programs to consider the use of bottom liners, recycle of solutions and conservation of water, dewatering of tailings, and neutralization to immobilize hazardous constituents; Pan 40, Appendix A, Criterion 5F, which requires that where ground-water impacts caused by seepage are occurring at an existing site, action be taken to alleviate the conditions that lead to seepage and that ground-water quality be restored, as well as providing technical specifications for the seepage control system and implementation requirements for a QA program; Pan 40, Appendix A, Criterion SG, which requires that licensees / operators perform site characterization in support of a tailings disposal system proposal: Pan 40, Appendix A, Criterion 5H, which requires steps be taken during stockpiling of ore to minimize penetration of radionuclides into underlying soils; Part 40, Appendix A, Criterion 7 which requires a year of monitoring prior to mill NUREG-1620 4-16 1
.- 0 operations; Part 40, Appendix A, Criterion 7A, which requires three types of monitoring systems:
detection, compliance, and corrective action; and Part 40, Appendix A, Criterion 13, which provides a list of hazardous constituents that must be considered when establishing the list of hazardous constituents in ground water at any site.
4.1.5 References Allison, J.D., D.S. Brown, and KJ. Novo-Gradac,1991, MINTEGA2PRODEff Geochemical Assessment Modelfor Environmental Systems: Version 3.0 User's Manual. Environmental .
Protection Agency Publication EPA /600/3-91/021,1991. l Gelhar, L.W., C. Welty, and K.R. Rehfeldt,1992, A critical review of data on field-scale dispersion in aquifers. Water Resources Research 28(7),1992.
NRC,1996, Staff Technical Position: Alternate Concentration Limits for Title II Uranium Mills, January 1996.
1 Parkhurst, D.L., Thorstensen, and L.N. Plummer,1980, PHREEQE-A Computer Programfor Geochemical Calculations. U.S. Geological Survey, Water Resources Investigation 80-96, 1980.
Smith A.D.1987, Nuclear Regulatory Commission, " Sampling of Uranium Mill Tailings Impoundments for Hazardous Constituents", Memorandum, February 9,1987, Division of Waste Management, Nuclear Regulatory Commisrion.
4.2 GROUND-WATER PROTECTION STANDARDS 4.2.1 Areas of Review Ground-water protection standards are established for each hazardous constituent. A hazardous constituent is defined in 10 CFR Part 40 Appendix A, Criterion 5B(2) as a constituent that meets all three of the following tests:
(1) The constituent is reasonably expected to be in or derived from the byproduct material in the disposal area; (2) The constituent has been detected in the ground water in the uppermost aquifer; and (3) The constituent is listed in Part 40, Appendix A, Criterion 13.
A hazardous constituent may be viewed as a constituent of concern that has been detected in the ground water in the uppermost aquifer. Even when constituents meet the three aforementioned tests, the l Commission may exclude a detected constituent from the set of hazardous constituents. ia site-specific basis, if it finds that the constituent is not capable of posing a substantial prewnt nor 4-17 NUREG-1620
potential hazard to human health nor the environment. In deciding whether to exclude constituents, the considerations identified in Part 40, Appendix A, Criterion 5B(3) must be considered. In addition, as required by Part 40, Appendix A, Criterion 5B(4), any underground sources of drinking water and exempted aquifers made by EPA will be considered. Relevant EPA guidance is provided in 40 CFR 144.7,144.3, and 146.4. The staff will review the technical basis the licensee has presented for the following elements of acceptable ground-water protection standards:
(1) The list of hazardous constituents; (2) A descript. ion of the POC; (3) Ground-water Protection Standards for hazardous constituents may be either:
(a) Commission-approved background concentrations, (b) MCLs, or (c) ACLs.
Alternatively, the existing license may be referenced to determine acceptable ground-water protection standards.
The staff shall also review additional ground-water protection standards that contain provisions for ground-water protection dealing with the design of surface impoundments and tailings disposal cells.
Evaluation of disposal system performance is addressed in SRP Section 4.3.3.
4.2.2 Review Procedures The reviewer shall examine the ground-water protection standards to verify that they have been defined consistent with the acceptance criteria in SRP Section 4.3.2. Specifically, the reviewer shall reference the existing license or:
s) Verify uat the licensee has identified all hazardous constituents that are present i Ae tailings leachate.
(2) Verify that the POC has been properly delineated.
(3) Evaluate whether the proposed concentration limits for each ground-water Protection Standard are within a range that is reasonably expected to represent background concentrations; or, if any ACLs are proposed, verify that the appropriate evaluations have been presented in accordance with Criterion 5(B)(6) of Part 40, Appendix A.
l 4.2.3 Acceptance Criteria I J
l Ground-water protection standards establish a concentration limit for each hazardous constituent, at the point of compliance. The development of ground-water protection standards will be acceptable ifit meets the following criteria:
NUREG-1620 4-18
y ..'
(1) Hazardous constituents are identified using the definition given in Part 40, Appendix A.
Criterion 5(b). Ammonia and nitrate are included on the list.
(2) A POC is established in accordance with Part 40, Appendix A, Criterion 5B(1).
The POC is the location where the ground water is monitored to determine compliance with the ground-water protection standards. The objective in selecting the POC is to provide the earliest practicable warning that the impoundment is releasing hazardous constituents to the ground
, water. The POC must be selected to provide prompt indication of ground-water contamination on the hydraulically downgradient edge of the disposal area. The POC is defined as the intersection of a vertical plane with the uppermost aquifer at the hydraulically downgradient limit of the waste management area.
The " uppermost aquifer' is defined in 10 CFR Part 40, Appendix A as "...the geologic formation nearest the natural ground surface that is an aquifer, as well as lower aquifers that are hydraulically interconnected with this aquifer within the facility's property boundary."
, Therefore, a proper selection of the POC includes identification of POC locations in the aquifer nearest to the ground surface, as well as other aquifers that are hydraulically interconnected with that aquifer, as warranted by site-specific conditions.
When tailings are disposed of on site, the NRC generally interprets the downgradient limit of the waste management area to be the edge of the reclaimed tailings side slopes. However,it is not recommended that licensees be required to compromise the cover integrity to install monitoring wells at the actual edge of the reclaimed tailings.
(3) A concentration limit is specified for each of the hazardous constituents.
(a) Commission-Approved Background Concentrations Part 40, Appendix A, requires that the Commission-approved backgromd concentration be the background concentration, except for constituents listed in Table SC of Part 40, Appendix A , which, if present in excess of background, are subject to th respective MCL s listed in Table SC.
Proper statistical methods, as discussed in SRP Section 4.1.3, are used to determine the expected range of naturally occurring background (baseline) concentrations for each constituent of concern. Because background water quality exhibits natural fluctuations in both space and time, the question arises as to what concentration for each constituent of concem can be taken to be consistent with backgrourd conditions. Generally, a ground-water protection standard is determined for each constituent, below which the constituent is assumed to be in compliance with the background restoration criterion.
(b) Alternate Concentration Limits ACLs are established on a site-specific basis, provided it can be demonstrated that: (i) the constituents will not pose a substantial present or potential hazard to human health nor the environment, as long as the ACLs are not exceeded; and (ii) the ACLs are 4-19 NUREG-1620 u _ _ _ _ _ _ _ _ _ _ _ - . - - -
=
AI . ARA, considering practicable corrective actions. Licensees are required to implement detection monitoring programs to detect and identify site-specific hazardous constituents, and compliance monitoring programs to verify compliance wi.h the l
established site-specific standards for individual constituents. SRP Sections 4.33 and 4.43 provide acceptance criteria for determining potential hazards, and for ALARA demonstrations, respectively.
4.2.4 Evaluation Findings 1
If the staff's review, as described in SRP Section 4.2, results in the acceptance of the site ground-water j protection standards, the following conclusions may be presented in the TER.
NRC has completed its review of the ground-water protection standards at the uranium milling facility. This review included an evaluation using the review procedures in Section 4.2.2 and the acceptance criteria outlined in Section 4.23.
The licensee has acceptably identified the hazardous constituents and has established acceptable l concentration limits and cleanup standards . Established background levels are acceptable. Acceptable statistical methods, such as those in Haan (1977) and Hirsch. et al, (1992), have been used to establish the concentration limits. If ACLs have been requested, the licensee has acceptably supported the request with appropriate data and calculations. The licensee has established an acceptable POC at the edge of the tailings impoundment on the downgradient direction of hydraulic flow.
I On the basis of the information provided in the application and the detailed review conducted of the ground-water protection standards for the uranium milling facility, the staff has concluded that the information is acceptable and is in compliance with Part 40, Appendix A, Criterion 5B, which requires the NRC to establish a list of hazardous constituents, concentration limits, e. POC, and a compliance period; Part 40, Appendix A, Criterion 5(B)(5), which allows use of ACLs under certain conditions; Part 40, Appendix A, Criterion SC, which provides a table of secon&'.ry ct ocentration limits for certain wnstituents when they are present in ground water above background concentrations; Part 40, Appendix A, Criterion 7A, which requires three types of monitoring systems: detectio0.
compliance, and corre:tive action; and 10 CFR Part 40, Appendix A, Criterion 13, which provides a list of hazardous constituents that must be considered when establishing the list of hazardous constituents in ground water at any site.
4.2.5 References Haan, C.T.,1977,. Statistical Methods in Hydrology, Iowa State University Press 1977.
Hirsch, R.M., D.R. Helsel, T.A. Cohn, and EJ. Gilroy,1992, Statistical Analysis ofHydrologic Data, Handbook of Hydrology, D.R. Maidment, ed., New York, NY: McGraw-Hill, Inc.,1992.
43 HAZARD AND ALARA ASSESSMENTFOR ACLs 43.1 Areas of Review NUREG-1620 4-20
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ACLs must be protective of human health and the environment at the POE. The provisions for establishing ACLs in the existing regulations may be difficult to meet and may not even be feasible at specific sites, which may render the ACL standard a non-option at such sites. The ACL framework is not appropriate for cases in which the provisions for establishing ACLs that are protective of human health and the environment cannot be satisfied, including instances in which there is no appropriate corrective action to restore ground-water quality to the protective limits or standards, or where corrective action is ineffective, prohibitively expensive, or of an indefinite duration. Instances such as these would have to be submitted to the Commission as special cases outside the ACL framework, and will be addressed and decided on by the Commission on a case-by-case basis.
The staff shall review the following elements of ACL hazard assessments:
(1) Identification of a POE; (2) Characterization of the hazardous constituent source term and the extent of ground-water ;
contamination; i (3) Assessment of hazardous constituent transport in the ground water and hydraulically !
connected surface waters, and their adverse effects on water quality, including present and potential health and environmental hazards; (4) Assessment of human and environmental exposure to hazardous constituents, including the cancer risk and other health and environmental hazards; and (5) A demonstration that hazardous constituent concentrations will not pose substantial present nor j potential hazards to human health nor the environment at the POE, and that the ACLs are ALARA , considering practicable corrective actions.
4.3.2 Review Procedures The reviewer shall examine the information and assessments provided for establishing ACLs to make the following determination.
(1) The hazardous constituent source tenn has: (a) been characterized; (b) is sufficient to provide a defensible estimate of the types, characteristics, and release rates of hazardous constituents that have been or are anticipated to be released from the source term; and (c) the extent of ground-water contamination at the site has been defined.
(2) The rates and directions of hazardous constituent migration and transport in the ground water and hydraulically connected surface waters have been adequately determined.
(3) The pathways for human and environmental exposure to hazardous constituents have been ;
identified, and exposure magnitudes and effects, including the cancer risk, have been acceptably evaluated.
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(4) Proposed ACLs will attenuate sufficiently from the proposed ACL levels at the POC, to their protective health-based values at the POE (i.e., concentrations that are protective of human health and the environment), and there will be no adverse effects on the ground water or on surface-water quality that would cause substantial health or environmental hazards at or beyond the POE location (s).
The licensee's assessment of ground-water corrective action alternatives shall be reviewed in conjunction with the hazard assessment. Previous, current, and proposed practicable corrective actions shall be reviewed to determine if the licensee has demonstrated that the proposed ACLs are ALARA.
The demonstration should include identification of alternative corrective actions; assessment of their technical feasibility, implementation, costs, and benefits; and selection of preferred corrective actions.
433 Acceptance Criteria The hazard and ALARA assessments for ACLs will be acceptable if they meet the following criteria:
(1) A hazard assessment is performed, that in accordance with Part 40, Appendix A, Criterion 5B(6), and as required by Part 40, Appendix A. Criterion SB(4), considers any underground sources of drinking water and exempted aquifers identified by EPA.
The hazard assessment reviewer shall consider all factors listed in Part 40, Appendix A, Criterion 5B(6)(a) and (b), as they apply to the site conditions. The assessment addresses the present and potential health and environmental hazards, including the cancer risk caused by human exposure to radioactive constituents and other health hazards that may be caused by the chemical toxicity of constituents.
I The acceptability of the proposed ACL values is based on a finding that the constituent will not pose a substantial present nor potential hazard to human health and the environment as long as the ACL is not exceeded. The use of previously established and documented health-based constituent concentration limits in the hazard assessment is used as a basis for establishing ACL values at specific sites, or such values are determined for constituents for which health-based concentration limits have not been established.
(2) The POE is identified.
The POE is defined as the location (s) at which people, wildlife, or other species could j reasonably be exposed to hazardous constituents from the ground water. For example, the POE may be represented by one or more domestic wells that could be constructed and could result in l withdrawal of contaminated ground water, or the locations at which aquatic biota may be !
exposed to hazardous constituents as a result of contaminated ground-water discharge to a river. In most cases, the POE is located at the dow agradient edge of the land that will be i transferred to either the Federal Govemment or the State for bng-term institutional control after the license is terminated. It is noted that the concept of a POE is specifically for the j assessment of potential hazard to human health and the environment. Established concentration j limits, whether background, MCLs, or ACLs, must always be met at the POC. ;
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I l Contaminant attenuation through natural flushing or other processes between the POC and the POE is often depended on to reduce constituent concentrations in the ground water to acceptable health-based values at the POE. The spatial relationship between the POC and POE is critical to the establishment of ACLs. Natural processes such as dilution, dispersion, decay, and sorption may attenuate hazardous constituents between the POC and POE. Thus, ACLs for hazardous constituents estabhshed at the POC may be greater than appropriate health and environmental concentration limits for those constituents at the POE, and still be protective of I human health and the environment. However, the assumption of a low-concentration ;
projection at the POE, based on POC monitoring, may not be valid in cases in which sthe contaminant plume for a particular constituent has already passed the POC and can no longer be detected by POC monitonng. The likelihood.of this situation developing at a specific site should be evaluated and analyzed by the licensee and addressed in the ACL application.
The POE, in most situations, will be located at the downgradient edge of the land that is ;
necessary for byproduct disposal which will be transferred to either the long-term custodian I where the site is located, for long-term institutional control after the license is terminated. In some instances, licensee's property boundary may be at a significant distance from the uranium mill tailings site.
A distant POE refers to any POE that is spatially beyond the area that the appropriate Federal or State agency is required to accept for perpetual care under the land-transfer provisions of ,
the Uranium Mill Tailings Radiation Control Act of 1978 as amended (UMTRCA). A distant l POE could be established at such a distant property boundary and justified, on the basis that land ownership by the licensee or the long-term care custodian would ensure that no water resource use would exist on the property. It should be noted that in some instances, a distant POE may be established without invoking land ownership or long-term custody; for example, when the possibility of human exposure is effectively impossible because the ground water is either inaccessible or unsui'able for use.
The licensee should carefully evaluate the consequences of the land-transfer provisions of UMTRCA and their effect on the POE location (s), with the long-term custodian, before proposing an ACL based on a distant POE. Under Title II of the UMTRCA, at the time hTC or an Agreement State terminates a license, the title to the land that is used for the disposal of any byproduct materials (tailings), as defined by Section 11.e(2) of the Atomic Energy Act of 1954 as amended (AEA), shall be transferred to the Federal Government or the State in which such land is located, at the option of each State. In some rare cases, the surface-land-ownership transfer requirements may be waived , such as with deep burial of tailings where ongoing site smveillance would not be required. Section 83.b of the AEA specifically requires that the land used for disposal of any Section Ile(2) byproduct materials be transferred to the Federal Government or State for long-term institutional control.
When a distant POE is involved, the licensce is required to coordinate and work with NRC to determine whether the State or the Federal Government will be the long-term site custodian after the termination of the NRC license, and to provide necessary documentation that can be us .d to secure a commitment from that party to take custody of the site. ACLs may not be established at sites involving a distant POE unless and until the licensee agrees to transfer the 4-23 NUREG-1620
- i title to the land, and the appropriate Federal or State govemment commits to take such land, including the land between the POC and POE that is in excess of the land used for disposal of byproduct material. In instances in which the licensee chooses to keep the mill property under a specific license and apply for an ACL as part of a compliance monitoring program, the s licensee would still be required to coordinate and work with NRC to secure a commitment from the State or from the Federal Government Agency that will accept the transfer of the specific property after the tennination of the specific license, including land in excess of that used for disposal of byproduct material.
Written assurance must be secured, either by the licensee or NRC, that the appropriate Federal or State agency will accept the transfer of the specific property, including land in excess of that needed for tailings disposal. ACLs are not established at sites with a distant POE unless and until the licensee agrees to transfer the title to the land, and the appropriate Federal or State govemment commits to take such land.
In cases in which the POE will be located at the edge of the land that NRC determines is necessary for disposal of byproduct material as defined in Section 1le(2) of the AEA - J including those lands necessary to accommodate the design features of the erosion control system, reasonable extensions necessary for perimeter roadways, and extreme site terrain features-- State or Federal Govemment advance commitment and corresponding Commission corresponding approval would not be required. It is noted that in some instances, a distant POE is established without invoking land ownership or long-term custody: for example, when the possibility of human exposure is effectively impossible because the ground water is either l inaccessible or unsuitable for use. I When ground-water flow ' contributes to surface water, the recipient surface water will be considered as a POE location. Proposed ACLs will not result in: (1) hazardous constituent i concentrations in the surface water that are in excess of the protective health or environmental limits; and (2) exposure of human and environmental receptors to contaminated ground water will not occur between the POC and the location at which the ground water discharges to the surface water.
I (3) The hazardous constituent source term and the extent of ground-water contamination are characterized.
Characterization of the contaminant source (s) and their extent provides the source term for j contaminant transport assessments. The source characterization provides reliable estimates of the release rates of hazardous constituents as well as constituent distributions. l The source term characterization provides relevant information about the facility, I including: (a) the uranium recovery processes used; (b) types and quantities of the j reagents used in milling; (c) milled-ore compositions; and (d) historical and current waste management practices. This information is considered, in conjunction with the i physical and chemical composition of the waste and the type and distribution of existing contaminants, to characterize the source term and evaluate future hazardous constituent release into the ground water (e.g., location of waste discharges, retaining stmetures for wastes, and waste constituents).
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NUREG-1620 4-24 l
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Depending on the hazardous constituents present, additional information on them and their propenies is provided including: (a) density, solubility, valence state, vapor i pressure, viscosity, and octanol-water partitioning coefficient; (b) presence and effect of complexing ligands and chelating agents, to the extent that constituent mobility may be
[
enhanced; (c) potential for constituents to degrade because of biological, chemical, and physical processes; and (d) constituent attenuation propenies, considering such processes as ion exchange, adsorptio::, absorption, precipitation, dissolution, and ultrafiltration.
l At sites with well-defined contaminant plumes, the spatial distribution of the various l hazardous constituents is specified. This information calibrates contaminant transpon l models and suppons evaluations of whether humans and environmental populations are being exposed to elevated concentrations of hazardous constituents. Characterization of L the contamination extent includes: (a) the type and distribution of hazardous constituents l in the ground water and contamination sources;(b) the monitoring program used to l delineate and characterize hazardous constituent distribution: and (c) documentation of the sampling, analysis and QA programs followed in the implementation of the site monitoring programs. Such information is used to assess present human and environmental population exposure to elevated concentrations of hazanious constituents, calibrate contaminant transpon models, and evaluate projected future exposures.
'(4) The hazardous constituent transpon in ground water and hydraulically connected surface water and the adverse effects on water quality, including the present and potential health and environmental hazards, are assessed.
The hydrogeologic and contaminant transpon assessment provides and documents estimates of projected contaminant distribution, including contaminant transpon and degradation and attenuation mechanisms between the POC and the POE. The assessment generally characterizes and provides information on: (a) site hydrogeologic characteristics, including ground-water flow direction and rates; (b) background water quality; and (c) estimated transpon rates, geochemical attenuation, and concentrations of hazardous constituents in the ground water and hydraulically connected surface water.
The acceptance criteria for these data are contained in SRP Section 4.3.2 of this chapter.
All likely and significant pathways of hazardous transpon in ground water and surface water should be identified and assessed. Estimated hazardous constituent concentrations and projected distributions are either best estimates or reasonably conservative representations of the rate, extent, and direction of constituent transport.
i Projections should be calibrated based on site-specific information. When there is great uncenainty in the attenuation-rate estimate, the licensee may rely on measurements of i constituent concentrations at the POC and the POE over a sufficient time period, before )
ACLs are established, to verify the projected attenuation rate. !
Contaminant attenuation through natural flushing between the POC and the POE can be depended on to reduce constituent concentrations in the ground water to their respective health-based values at the POE. Therefore, the licensee may be able to exercise some control over contammant attenuation that can be accomplished through natural flushing ,
i 4-25 NUREG-1620
at a particular site by proper selection of the POE location, as permitted by the site-specific conditions.
If licensees propose the use of natural flushing beyond the POE, the reviewer will need to determine if the altematives provision of Part 40, Appendix A have been meet. In order to find natural flushing acceptable, the licensee will need to assess the health, safety, and environmental impacts associated with the proposal. The licensee should also work with the long-term custodian to determine the need for an indemnification agreement following site transfer to cover circumstances where natural flushing does not conform to the models that were used to justify it's use. In addition, the reviewer should determine if increased monitoring is required, and what amount should be included in the long-term care fund to account for this increased monitoring. Finally, the licensee needs to demonstrate that the economic benefit and equivalent safety provisions of Part 40, Appendix A have been met.
(5) An assessment of human or environmental exposures to hazardous constituents, including cancer risk and other health and environmental hazards, is provided.
The exposure assessment identifies the maximum levels permissible at the POC that are protective of human health and the environment at the POE by evaluating human and environmental exposure to hazardous constituents and then demonstrating that the proposed ACLs do not pose substantial present nor potential hazards to human health or the environment.
The exposure assessment at specific sites evaluates health and environmental hazards using water classification and water use standards, and existing and anticipated water uses.
Agricultural, industrial, domestic, municipal, environmental, and recreational water uses, as they pertain to the site, are considered. The assessment identifies and evaluates hazardous constituent exposure pathways and makes projections of human and environmental population itsponse based on the projected constituent concentrations, dose levels, and available information on the radiological and chemical toxicity effects of hazardous constituents. The assessment addresses the underlying assumptions and variability of the projected health and environmental effects.
The human exposure assessment is evaluated primarily on the basis of the extent to which people are using, and are likely to use, contaminated water from the site. Site-specific water uses are determined on the basis of the following considerations: (a) ground-water quality in the site area and present water uses: (b) statutory or legal constraints and institutional controls on water use in the site area: (c) Federal, State, or other ground-water classification criteria and guidelines: (d) applicable water use criteria, standards, and guidelines: and (e) availability and characteristics of alternative water supplies.
The human exposure assessment considers two potential exposure pathways: (a) ingestion of contaminated water and (b) ingestion of contaminated foods. The assessments distinguish between health effects associated with threshold and nonthreshold constituents. Mutagenic, teratogenic, and synergistic effects are considered in the analysis, if applicable, based on toxicological testing, structure-activity relationships, or epidemiological studies. Other NUREG-1620 4-26 I
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pathways that may impact human health, such as dermal contact and inhalation, are also to be l considered, but need not always be assessed, unless it is determined that these exposures could
! result in significant hazards to human health or the environment.
1 The assessment of adverse effects associated with present and potential human exposure to hazardous constituents should be based on the exposure pathways characterization. The human exposure assessment includes: (a) classification of affected water resources;(b) assessment of
- existing and potential water uses;(c) evaluation of the likelihood that people will be exposed to l hazardous constituents; and (4) evaluation of adverse effects associated with exposure to l hazardous constituents, including assessment of the permanence and persistence of adverse effects.
Assessments of the probability of human exposure are often difficult to establish quantitatively.
i Consequently, defensible qualitative estimates are often necessary, and can be characterized as
! either:
(a) Reasonably likely - when exposure has or could have occurred in the past, or available information indicates that exposure to contamination may reasonably i occur during the contamination period, or (b) Reasonably unlikely - when exposure could have occurred in the past, but will probably not occur in the future, either because initial incentives for water use ,
have been removed, or because available information indicates that no incentives '
for water use are currently identifiable, based on foreseeable technological developments.
Information in support of the exposure assessment should be supplied, or relevant information and studies; such as those available from the International Commission on Radiological Protection and the National Council on Radiation Protection and Measurement, for the effects of radioactivity, and EPA's Integrated Risk Information System, for chemical-toxicity effects, should be referenced. Altematively site-specific information provided in previous reports, such as the license application or the environmental report, can be referenced. A technical basis to establish a reasonable assurance that the proposed ACLs do not pose a hazard to human health or the environment should be provided for each constituent for which an ACL may be established.
Exposure determinations should consider existing and potential water uses. Potential uses include those uses that are reasonably sure to occur (i.e., anticipated use) and uses that are compatible with the untreated background water quality (i.e., possible use). Past uses may be included as existing or potential uses.
Water resource classification of existing and potential water use should include: (a) domestic and municipal drinking-water use; (b) fish and wildlife propagation; (c) special ecological communities; and (d) industrial, agricultural, and recreational uses. The classification of existing and potential uses of water at the facility should be consistent with Federal, State, and local water-use inventories. The ground-water classification in EPA's " ground-water Protection Strategy"(i.e., Class I, II, or III) should also be included. In this classification 4-27 NUREG-1620 i
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scheme, Class I ground water represents an irreplaceable drinking water source or provides the base-flow for a particularly sensitive ecological system. Class II ground water is currently
] i used or potentially available for drinking or other beneficial uses. Class III ground water is heavily saline with a total dissolved solids content of more than 10,000 parts per million (ppm),
or otherwise contaminated beyond levels that allow cleanup, using methods that are reasonably employed in public water system treatment, and that do not migrate into Class I or Class II 1 ground waters or discharge and degrade surface waters. For Class I and Class II ground water, it is acceptable to assume that exposure is likely to occur unless the licensee demonstrates that exposure of humans and unique habitats to contamination is effectively l impossible. Exposure for Class III ground water is not generally evaluated unless the water is currently used, or a future beneficial use is anticipated. When water-use standards are inconsistent among several intended water uses, the more stringent criteria will be applied. i d
Water yields, costs for development of alternate water supply sources, and legal, statutory, or j other administrative constraints on the use and development of the water resources should be l
verified. '
The cancer risk should be evaluated for individual constituents, including radioactive and carcinogenic cb .nicals, and compared with the maximum permitted risk level. The health effects of non-radioactive and non-carcinogenic constituents that are chemically toxic will be evaluated considering their risk-specific Jose (RSD) levels, and for some chemicals unat have threshold effects, it will be necessary to calculate a Hazard Index using the reference doses !
(RfDs). The Hazard Index is the ratio of calculated intake to the RfD, and an acceptable Hazard Index must be less than unity.
(
Reasonably conservative or best estimates of potential health effects caused by human exposure to hazardous constituents should include an assessment of potential health hazards for each constituent for which an ACL is proposed, based on compatisons of existing and projected constituent concentrations with appropriate exposure limits and dose-response ,
l relationships from available literature. This assessment of potential health hazards should include the MCLs, RfDs, or RSDs. MCLs represent the EPA standards for drinking water; they are found in Pan 40, Appendix A, Table SC. RfDs are the amounts of toxic constituents to which humans can be daily exposed without suffering any adverse effect. RSDs are the amounts of proven or suspected carcinogenic constituents to which humans can be daily exposed, without increasing their risk of contracting cancer, above a specified risk level.
MCLs, RfDs, and RSDs for most hazardous constituents in uranium mill tailings can be obtained from EPA. The RfD and RSD assessment assume a human mass of 70 kg (154 pounds) and consumption of 2 liters of water per day (0.53 gallon / day). More stringent criteria l may apply if sensitive populations are exposed to hazardous constituents. MCLs, RfDs, and/or RSDs, can be used to show compliance with the risk level and Hazard Indices. In the absence {
of applicable MCLs, RfDs, or RSDs, a technical basis for the risk assessment can base dose-response relationships on literature searches or toxicological research. ' The exposure analysis should distinguish between threshold (toxic) and non-threshold (carcinogenic) effects associated with human exposure, as well as teratogenic, fetotoxic, mutagenic, and synergistic effects.
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NUREG-1620 4-28 I
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l The cumulative effects of hu : a exposure to hazardous constituents for which ACLs are proposed and other constituents present in contaminated ground water will be maintained at a l level adequate to protect public bealth. The combined effects from both radiological and non-radiological constituents should be considered.
Proposed human exposure levels should be reasonably conservative, defensible, and l sufficiently protective of human health to avoid a substantial present or potential hazard to l l people for the estimated duration of the contamination. When considering the potential for health nisks from human exposure to known or suspected carcinogens in the use of ground water for drinking purposes, an ACL would be acceptable ifit does not pose an excess lifetime risk of fatal cancers to an average exposed individual at the POE on the order of 10" or more
! from individual constituents.
I i Potential responses of environmental or nonhuman populations to the various hazardous constituents are assessed if such populations can realistically be exposed to contaminated ground water or hydraulically connected surface water. Terrestrial and aquatic wildlife, plants, j livestock, and crops are included in the assessment. In the absence of available information that readily may be used to demonstrate that there will be no substantial environmental impacts caused by ground-water contamination from the site, the exposure assessment provides: (a) l- inventories of potentially exposed environmental populations; (b) recommended tolerance or exposure limits; (c) contaminant interactions and their cumulative effects on exposed populations; (d) projected responses of environmental populations that result from exposure to hazardous constituents; and (e) anticipated changes in populations, independent of the hazardous constituent's exposure. Altematively, a licensee demonstrates that environmental hazards are not anticipated, because exposure will not occur.
The potential for adverse effects, such as: (a) contamination-induced biotic changes, (b) loss or reduction of unique or critical habitats, and (c) jeopardizing endangered species should be described. Consultation with the U.S. Fish and Wildlife Service is required under the Endangered Species Act, if an endangered or threatened species is found on the site, or is i believed to inhabit the site. Terrestrial wildlife exposure to constituents through direct exposure and food-web interactions should be considered. Aquatic wildlife effects are evaluated by comparing estimated constituent concentrations with Federal and State water- i quality criteria.
Agricultural effects from both direct and indirect exposure pathways, crop impacts, reduced productivity, and bioaccumulation of constituents should be considered. Reasonably conservative estimates of constituent concentrations are compared with Federal and State water-qua.lity criteria to estimate agricultural effects associated with constituent exposure.
Additionally, crop exposures through contaminated soil, shallow ground-water uptake, and
- irrigation, along with livestock exposure through direct ingestion of contaminated water and indirect exposure through grazing, should be assessed. ;
When appropriate, the hazard assessment considers potential damage to physical structures (e.g., from corrosiveness), that may result from exposure to the hazardous constituents in ground water and hydraulically connected surface water. Alternatively, a licensee demonstrates that damage to physical structures is not anticipated, because the exposum will not occur. ,
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% I For physical structures, such as foundations, underground pipes, and roads, the reviewer ensures that estimated constituent concentrations will not result in any significant degradation or loss of function as a result of contamination exposure.
(6) An ALARA demonstration is provided.
Applications for ACLs must demonstrate that the proposed limits are ALARA, considering practicable corrective actions, as required in Criterion 5B(6) of Appendix A The licensee demonstrates,in accordance with the requirements of Part 40, Appendix A, Criterion 5B(6), that existing levels of ground-water contamination are ALARA. The licensee provides an assessment of ground-water corrective actions performed at the site. ground-water corrective action assessments typically: (a) identify practicable corrective action altematives, and assess their technical feasibihty, costs, and benefits; (b) assess the potential for each corrective action attemative to reduce contaminant levels to below MCLs established in the hazard assessment; (c) select an appropriate corrective action that will achieve concentration levels below the MCL for each contaminant determined by the hazard assessment; and (d) demonstrate that practicable corrective actions are not likely to result in reduction of contamination below the proposed ACL, and that ACLs are therefore ALARA l To select a corrective action altemative and a target conventration level that meets the ALARA provision, the corrective action assessment provides information on the costs and benefits of each of the corrective action altematives considered by the licensee. This information includes calculations and assumptions. It may not be necessary in some cases to select and adopt the most stringent alternative if it can be demonstrated that the cost ofimplementing such an altemative is too high compared with the expected l
benefits.
1 Previous, current, and proposed practicable corrective actions are reviewed to determine if the licensee has demonstrated that the proposed ACLs are ALARA. The demonstration includes identification of alternative corrective actions; assessment of their technical feasibility, implementation, costs and benefits; and the selection of l practicable corrective actions. Ground-water corrective-action assessments for ALARA !
evaluations should typically: (a) identify target concentration levels that are at or below l the MCL determined by the hz.zard assessment; (b) identify practicable corrective-action l attematives, and assess their technical feasibility, costs, and benefits; (c) select appropriate corrective action; and (d) demonstrate that the proposed coricentration limits are ALARA, considering practicable corrective actions.
1 The ground-water corrective-action alternative assessments should ensure that: (a) a complete range of reasonable altemative corrective actions has been identified; (b) the j identified corrective actions are feasible and appropriate to reduce coastituent )
concentrations at the site; (c) the corrective actions have been designed to optimize their effectiveness; and (d) an objective comparison of the costs and benefits associated with the corrective actions is complete. l
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NUREG-1620 4-30 I
Corrective-action alternatives should be based on cleanup goat Jiat are at or below the concentration limit determined by the hazard assessment to be protective of human health and the environme~ 4t least three different target concentration levels that are at or below the level identL . in the hazard assessment and that can reasonably be attained by practicable corrective tion should generally be proposed and evaluated t y the licensee. The costs and benefits of each of the corrective-action alternatives should be supported by appropriate documentation, calculations, and assumptions. It may not be necessary in some cases to select and adopt the most stringent alternative ifit can be demonstrated that the cost of implementing such an alternative is too high, compared with the expected benefits.
Different corsective actkns are currently m operation at uranium mill sites. These corrective actions, thet .esults, and their application at other sites can serve as the basis for a licensee's selection of a corrective-action program. Projections of hazardous-constituent concentrations at specific corrective-action measures could be based on previous experience and data obtained from the implementation of such measures at other sites.
The corrective actions should be selected and designed to optimize the effectiveness in reducing hazardous-constituent concentrations. This may be demonstrated with backup calculations that provide approximations of tne effects of the proposed actions on the ground-water quality under the site-specific hydrogeologic conditions.
The direct and indirect benefits of implementing each of the identified corrective actions should be compared with the costs of performing (or not performing) such measures.
The cost estimates include consideration of capital costs for design, implementation, and decommissioning, along with operation anu maintenance costs. The reviewer verifies estimates of the current and projected value of pre-contaminated water resources, based on water rights, availability of altemative water supplies, and projected water-use demands. The reviewer generally considers the value of potentially contaminated water resources as equal to either the cost of domestic or municipal drinking-water supplies, or the cost of supplied water to replace the contaminated resources. The absence of
, alternative water supplies increases the relative value of potentially contaminated water resources. The adequacy of the benefits assessment is similarly evaluated, considering the avoidance of adverse health effects, value of pre-contaminated ground-water resources, prevention of land-value depreciation, and benefits acemed from performing the corrective action.
Ground-water corrective action assessments will be approved and ACLs will be established at specific sites ifit can be demonstrated that the proposed ACLs are no higher than the allowable MCLs determined by the hazard assessment, and that they also represent the lowest practicably achievable concentration levels, considering practicable corrective-action alternatives. The determination that the proposed practicable corrective-action measures satisfy the ALARA requirement should include guidance in Appendix I to 10 CFR Part 50, Report Number 39, and the International Commission on Radiological Protection Publication 22.
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e v 4.3.4 Evaluation Findings If the staff's review, as described in this SRP Section 4.3,lesults in the acceptance of the site hazard and ALARA assessment for ACL evaluations, the following conclusions may be presented in the TER.
The NRC has completed its review of the site hazard and ALARA assessment for ACL evaluations at the uranium milling facility. This review included an evaluation using the review procedures in Section 4.3.2, and the acceptance criteria outlined in Section 4.3.3.
The licensee has performed an acceptable hazard assessment by considering present and potential health and environmental hazards, including cancer risk by human exposure to radioactive constituents and other nealth hazards resulting from the chemical toxicity of the constituents. The POE has been identified and is acceptably sited at the downgradient edge of the affected land. When a distant POE is used, written assurance has been secured, either by the licensee or NRC, that the appropriate Federal or State agency will accept the transfer of the specific property, including land in excess of that needed for tailings oisposal. The hazardous constituent source term and the extent of ground-water contamination have been acceptably characterized. The transport of the hazardous constituent in ground water and surface water has been defined and any adverse effects on water quality, including present and future, have been assessed. The cancer risk and other health and environmental hazards from human or environmental exposures to hazardous constituents have been evaluated acceptably including: (a) identification of maximum levels permissible at the POC; (b) evaluation of health and environmental hazards using water classification and use standards and existing and anticipated water uses; (c) appropriate consideration of impact, based on site-specific water uses; (d) consideration of ingestion of contaminated water and food; (e) consideration of response of environmental and nonhuman populations to the various hazardous constituents including terrestrial and aquatic wildlife, plants, livestock, and crops; and (f) consideration of potential damage to physical structures. The acceptable ALARA demonstration includes:(1) an assessment of ground-water corrective actions dealing with identification of practicable corrective action alternatives;(2) evaluation of ability of corrective action to reduce contaminant levels appropriately; (3) demonstration that action will achieve desired concentration levels; or, as required; and (4) demonstration that practicable corrective actions are not likely to result in reduction of contamination below the proposed ACL, and that ACLs are therefore ALARA.
In cases where the licensee has proposed the use of natural flushing beyond the point of exposure as an altemative to Part 40, Appendix A, the staff has evaluated the licensee's proposal that natural flushing would met the economic benefit and equivalent safe'.y provisions of Part 40, Appendix A . Therefore, the use of flushing meets the alternatives require sent in Part 40, Appendix A.
I On the basis of the infonnation provided in the application and the detailed review conducted of the site '
hazard and ALARA assessment for ACL evaluations for the uranium milling facility, j the staff has con.luded that the information is acceptable and is in compliance with 10 CFR Part 40, l Appendix A, Criterion 5B, which requires NRC to establish a list of hazardous con ;tituents, j concentration limits, a POC, and a compliance period; Part 40 Appendix A, Criterion SC, whi:h provides a table of secondary concentration limits for certain constituents when they are present in ground water above background concentrations; Part 40, Appendix A, Criterion 5F, which requires that where ground-water impacts from seepage are occurring at an existing site, action must be taken to alleviate the conditions that lead to seepage, and ground-water quality must be restored, including technical specifications for the seepage control system and implementation of a QA program; Part 40, NUREG-1620 4-32
Appendix A, Criterion SG, which requires licensees / operators to perform site characterization in support of a tailings disposal system proposal; Pan 40.31(f), which requires inclusion of an Environmental Repon in the license application, and 10 CFR 51.45, which requires a description of the affected environment, containing sufficient data to aid the Commission in its conduct of an independent analysis.
4.3.5 References None. j i
4.4 GROUND WATER CORRECTIVE ACTION AND COMPLIANCE MONITORING PLANS 4.4.1 Areas of Review The staff shall review any ground-water Corrective Action Plan that may be submitted by the licensee either as a pan of the RP, cr as a separate licensing submittal. A separately submitted Conective Action Plan will contain much of the same information that is required for the RP (e.g., a site characterization ,
and a monitoring plan). Any information that was included in a previously approved RP may be incorporated by reference. For review of some information, the reviewer may use review procedures in other chapters of this SRP. The following are specific portions of a Cormctive Action Plan to be reviewed.
(1) Selection of a ground-water compliance strategy, (2) The remedial action design and implementation plan, (3) Waste management practices, (4) Institutional controls, I (5) ground-water monitoring plans, and ;
i (6) Surety.
4.4.2 Review Procedures The reviewer shall examine Corrective Action Plans and compliance monitoring plan information to verify the following:
(1) The selected ground-water compliance strategy is likely to result in timely compliance with established standards.
(2) The remedial action design and the implememation plan are appropriate for the site characteristics, and clearly defined restoration cleanup standards have been defined.
(3) Waste management practices are in compliance with environmental protection regulations.
4-33 NUREG-1620
e (4) Institutional controls during the restoration period are sufficient to prevent significant hazards to human health and the environment.
(5) The ground-water monitoring system is sufficient to verify the performance of the selected restoration strategy, and to monitor the long-term performance of any onsite tailings disposal cells.
1 (6) Surface impoundment constructed as part of the program are designed t meet the requirements of Part 40, Appendix A, Criteria and are included in the dam safety program if appropriate.
4.4.3 Acceptance Criteria In Part 40, Appendix A, Criterion SD, NRC requires that if the ground-water protection standards established under paragraph 5B(1) of Part 40, Appendix A, of this criterion, are exceeded at a licensed site, a corrective actian program must be put into operation as soon as is practicable, and in no event later than 18 months after the Commission finds that the standards have been exceeded. The licensee shall submit the proposed corrective action program's supporting rationale for Commission approval, before putting the program into operation, unless otherwise directed by the Commission. The objective of the program is to return hazardous constituent concentration levels in ground water to the concentration limits set as standards. The corrective action should result in conformance with the established concentration limits, address either removing the hazardous constituents or treating them in place, and include a program to monitor compliance with cleanup standards. Regulations do not require any specific designs or methods to be used for the ground-water corrective action program. Because of the nearly limitless possibilities for designing and implementing ground-water corrective actions, staff reviewers shall focus on the technical feasibility from an engineering perspective and c valuate whether '
the proposed design is likely to result in timely compliance with established concentration limits and whether the monitoring program is adequate to verify the effectiveness of the design. Because consideration of all possible engineering design options is beyond the scope of this SRP, the reviewer shall rely on knowledge of ground-water restoration and monitoring technology to determine whether a proposed design is acceptable. If natural flushing is proposed, the reviewer will need to consider this as an alternative under Part 40, Appendix A. In this situation, the reviewer will need to look at the technical acceptability of the proposal along with the economic benefit and equivalent safety protection discussed in the introduction to Pan 40, Appendix A. A ground-water corrective program or a compliance ,
monitoring prograri will be acceptable if it meets the following criteria: )
(1) The ground-water compliance strategy selection is appropriate for the site. l NRC has found two strategies to be acceptable for achieving compliance with ground-water protection standards :
(a) No remediation-This is an acceptable strategy e those sites that have no l ground-water contamination related to uranium processing activities, or where j contamination does not exceed either background levels, MCLs, or ACLs. l l
(b) Active remediation-Active remediation is required at when contaminants are l l
present at concentrations above background levels, MCLs, or ACLs.
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(2) Though the use of natural flushing is specifically allowed as restoration strategy at Title I mill sites, there are currently no specific regulations that allow the use of natural flushing of contaminated ground water to be the primary means of achieving compliance. Similarly,there is no specific requirement for the application of supplemental standards that may be used at Title I sites when contaminated aquifers are classified as limited use, or when ground-water remediation is considered technically impracticable.
This does not preclude the use of natural flushing as an approach for achieving compliance with ground water protection standards. Natural flushing can be used as long as the licensee can demonstrate protection of public health and the environment throughout the natural flushing period and can assure that adequate financial resources for the extended period the license will remain in effect.
If licensees propose the use of natural flushing the licensee will need to assess the health, safety, and environmental impacts associated with the proposal. The licensee should also work with the long-term custodian to determine the need for an indemnification agreement following site transfer to cover circumstances where natural flushing does not conform to the models that were used to justify it's use. In addition, the reviewer should determine if !
increased monitoring is required, and what amount should be included in the long-term care fund to account for this increased monitoring. Finally, the licensee needs to demonstrate that
)
the economic benefit and equivalent safety provisions of Part 40, Appendix A have been met.
(3) 'Ihe remedial action design and implementation is adequate.
When active remediation is necessary, a timetable for ground-water cleanup is established.
This timetable can be based on model predictions of likely restoration performance. When models are used to predict performance, a sensitivity analysis is performed to evaluate a variety of scena2ios and their effect on the expected system performance. All modeling input parameters are based on site characterization data or on technically justified assumptions.
There are as many potential active remediation designs as there are contaminated sites. As l' such, it is beyond the scope of this SRP, and would le unnecessarily restrictive, to attempt to provide specific acceptance criteria for every possible active remediation scenario. In general, l l however,if active remediation methods are to be employed, a discussion of the type of active remediation is provided along with engineering specifications an analysis of effectiveness.
l l Engineering specifications include design details such as pumping / injection rates, treatment methods, equipment and maintenance requirements, plans and schedules for construction, and maps showing locations of equipment.
i An analysis is conducted to determine the expected effectiveness of the remediation system.
Analyses are conducted to demonstrate that:
I (a) The chosen active remediation technology is appropriate for the hydrogeologic and geochemical conditions at the site.
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(b) Design pumping rates are sustainable and sufficient to control the migration of contaminants away from the site.
(c) The effects of natural aquifer heterogeneity are properly and conservatively accounted for in the remediation strategy.
(4) Adequate waste management practices are defined.
The disposition of effluent generated during active remediation is addressed in the Corrective Action Plan. Appendix F contains NRC staff policy for effluent disposal at licensed Uranium Recovery Facilities for conventional mills. When retention systems such as evaporation ponds are used, design considerations from erosion protection and stability along with construction plans reviewed by a qualified engineer are included. Evaporation and retention ponds have leak-detection systems if they are to contain contaminated water. The leak-detection system is capable of reliably detecting an accidental leak through a liner. The areal coverage of the system is such that no leaks have the potential for undetected vertical or horizontal movement to the ground water. A typical system may consist of a highly permeable layer of sand directly under the liner. Perforated pipes are placed in the sand layer to drain to standpipes or sumps. This permeable layer overlies a less-permeable layer of compacted soil.
This arrangement ensures that scepage is horizontally through the sand toward the collector pipes.
If water is to be treated and reinjected, either into the upper aquifer or into a deep-disposal well, the injection program is approved by the appropriate State or Federal authority. If effluent is to be discharged to a surface-water body, licensees obtain a National Pollutant Discharge Elimination System permit for discharge to surface water. If plans to manage effluents are in pla:e from prior operations.
These plans may be included in the Corrective Action Plan by reference.
(5) Appropriate institutional control is provided for the site.
The purpose of institutional control is to protect human health and the environment from potential harm l while the site is being brought into compliance. Institutional control is accomplished by limiting access to the site with a fence, by conducting periodic inspections of the site, and by periodic monitoring of restoration performance.
l (6) Effective corrective action . d compliance monitoring programs are provided.
l l Licenses are required, by Criterion 7 of Appendix A to Part 40, to implement corrective action and
! compliance monitoring programs. The licensee's monitoring programs are adequate to evaluate the l effectiveness of ground-water restoration and control activities, and to monitor compliance with ground-water cleanup standards. The description of the monitoring program includes or references the following information:
(a) QA procedures used for collecting, handling, and analyzing ground-water samples; (b) The number of monitor wells and their locations; (c) A list of constituents that are sampled and the monitoring frequency for each monitored constituent; NUREG-1620 4-36
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(d) Action levels that trigger implementation of enhanced monitoring or revisions to cleanup activities (i.e., timeliness and effectiveness of the corrective action).
l Corrective Action For monitoring of restoration progress, the same wells used to determine the nature and extent of contamination may be used. However, once the extent of contamination is delineated, it may be possible to adequately monitor compliance with fewer wells. Once j selected, majoi changes to monitored locations are avoided, because it is important to be able to directly compare measurements made at different points in time, l
i During active restoration, licensees choose a monitoring interval that is appropriate for i the monitoring restoration progress, given the site conditions. Not all hazardous constituents need to be monitored at each interval. It is generally acceptable for licensees to choose a list of more easily measured constituents that serve as good indicators of restoration performance. These indicators include conservative constituents that am less likely to be attenuated such as chloride. total dissolved solvents (TDSs), and alkalinity.
ground water at designated monitor wells is sampled for all hazardous constituents at the end of each major phase of restoration, and again after a suitable observation period, l before license termination and transfer of 6 site to the custodial agency (DOE) for I long-tenn custody.
Compliance Monitoring After completion of surface remedial actions, gmund water at the POC is sampled for all hazardous constituents of concern. Ground water at the POC then undergoes an observational period before license termination. Although there is no regulatory requirement for an observational period, one is necessary for NRC to effectively assess potential long-term stability of the tailings disposal cell. The length of this observational period is determined on a site-specific basis, with a minimum period of 1 year. This period commences either at the completion of the construction of the erosion cover, or, when the site has continuing ground-water restoration, after completion of restoration activity. At the end of this period, before license termination and transfer of the site to the custodial agency, ground water at the POC is again, sampled as described in SRP Section 4.5.3.
Termination of Cormctive Action The ground-water monitoring program and other information should provide reasonable assurance that the ground-water protection standard will not be exceeded.
(7) Design of Surface Impoundments The reviewer shall determine that any lined impoundment built as part of the corrective action program s to contain wastes is acceptably designed, constructed, and installed. The design, installation, and operation of these surface impoundments must meet relevant guidance provided in Regulatory Guide 3.11, Section 1 (U.S. Nuclear Regulatory Commission,1977). Materials used to construct the liner shall 4-37 NUREG-1620
be reviewed to determine that they have acceptable chemical propenies and sufficient strength for the design application. The reviewer shall determine that the liner will not be ovenopped. The reviewer shall determine that a proper quality control program is in place.
The review shall ensure that the applicable requirements of 10 CFR Part 40, Appendix A, Criterion 5(A) have been met. If the waste water retention impoundments are located below grade, the reviewer shall determine that the surface impoundments have an acceptable liner ensure protection of ground water.
The location of a surface impoundment below grade will eliminate the likelihood of embankment failure that could result in any release of waste water. The reviewer shall determine that the design of associated dikes is such that they will not experience massive failure.
s The design of a clay or synthetic liner and its component parts should be presented in the application or related amendment applications for a uranium recovery operation. At a minimum, design details, drawings, and pertinent analyses should be provided. Expected construction methods, testing criteria, and quality assurance programs should be presented. Planned modes of operation, inspection, and maintenance should be discussed in the application. Deviation from these plans should be submitted to and approved by .ae staff before implementation.
The liner for a surface impoundment used to manage uranium and thorium byproduct material must be designed, constructed, and installed to prevent any migration of wastes out of the impoundment to the subsurface soil, ground water, or surface water at any time during the active life of the surface impoundment. The liner may be constructed of materials that allow wastes to migrate into the liner provided that the impoundment decommissioning includes removal or decontamination of all waste residues, contaminated containment system components, contaminated subsoils, and structures and equipment contaminated with waste and leachate.
The liner must be constmeted of materials that have appropriate chemical properties and sufficient strength and thickness to prevent failure because of pressure gradients, physical contact with the waste or j leachate, climatic conditions, and the stresses ofinstallation and daily operation. The subgrade must be sufficient to prevent failure of the liner because of settlement, compression, or uplift. Liners must be installed to cover all surrounding canh which is likely to be in contact with the wastes or leachate. l Tests should show conclusively that the liner will not deteriorate when subjected to the waste products l and expected atmospheric and temperature conditions at the site. Applicant test data and all available manufacturers' test data should be submitted with the application. For clay liners, tests, at a minimum, should consist of falling head permeameter tests performed on columns of liner material obtained during !
and after liner installation. The expected reaction of the impoundment liner to any combination of l solutions or atmospheric conditions should be known before the liner is exposed to them. Field seams of !
synthetic liners should be tested along the entire length of the seam. Representative sampling may be used for factory seams. The testing should use state-of-the-an test methods recommended by the liner manufacturer. Compatibility tests that document the compatibility of the field seam material with the waste products and expected weather conditions should be submitted for staff review and approval. Ifit j is necessary to repair the liner, representatives of the liner manufacturer should be called on to supervise i the repairs.
1 Proper preparation of the subgrade and slopes of an impoundment is very imponant to the success of the surface impoundment. The strength of the liner is heavily dependent on the stability of the slopes of the NUREG-1620 4-38
subgrade. The subgrade should be treated with a soil steritant. The subgrade surface for a synthetic liner should be graded to a surface tolerance of less than 2.54 cm (1 in) across a 30.3-cm (1-ft ) straightedge.
NRC Regulatory Guide 3.11, Section 2 (U.S. Nuclear Regulatory Commission,1977) outlines acceptable methods for slope stability and settlemeni analyses, and should be used for design. If a surface impoundment with a synthetic liner is located in an area where the water table could rise above the bottom of the liner, under drains may be required. The impoundment will be inspected in accordance with Regulatory Guide 3.11.1 (U.S. Nuclear Regulatory Commission,1980).
To prevent damage to liners, some form of protection should be provided, including: (i) soil covers; (ii) venting systems; (iii) diversion ditches; (iv) side slope protection; or (v) game-proof fences. A program for maintenance of the liner features should be developed, and repair techniques should be planned in advance.
The surface impoundment must have sufficient capacity and must be designed, constmeted, maintained, and operated to prevent overtopping resulting from: (i) normal or abnormal operations, overfilling, wind end wave actions, rainfall, or run-on; (ii) malfunctions of level controllers, alarms, and other equipment; and (iii) human error. If dikes are used to form the surface impoundment, the dikes must be designed, constmeted, and maintained with sufficient structural integrity to prevent massive failure of the dikes. In insuring structural integrity, the applicant must not assume that the liner system will function without leakage during the active life of the impoundment.
Controls should be established over access to the impoundment, including access during routine maintenance. A procedure should be provided that assures that unnecessary traffic is not directed to the impoundment area.
In addition, the reviewer shall evaluate the proposed surface impoundment to determine if it meets the definition of a dam as given in Regulatory Guide 3.11 (U.S. Nuclear Regulatory Commission,1977). If this is the case, the surface impoundment should be included in the NRC Dam Safety Program, and be subject to Section 215, National Dam Safety Program of the Water Resources Development Act of 1996.
If the reviewer finds that the impoundment meets the defmition of a dam, an evaluation of the dam ranking (low or high hazard) shall be made. If the dam is considered a high hazard, an Emergency Action Plan is needed consistent with Federal Emergency Management Agency requirements. For low-hazard dams, no EAP is required. For either ranking of dam, the reviewer shall also determine that the licensee has an acceptable inspection program in place to ensure that the dikes are routinely checked, and that performance is properly maintained.
A quality control program should be established for the following factors: (i) clearing, gmbbing, and stripping; (ii) excavation and backfill; (iii) rolling; (iv) compaction and moisture control; (v) finishing; (vi) subgrade sterilization; and (vii) liner subdrainage and gas venting.
(8) Financial Surety Is Provided The licensee must maintain a financial surety, within the specific license, for the restoration of ground
, water, with the surety sufficient to recover the anticipated cost and time frame for achieving compliance,
( before the land is transferred to the long-term custodian. The financial sarety must be sufficient to cover i
the cost of corrective action measures that will have to be implemented if required to restore 4-39 NUREG-1620
ground-water quality to the established site-specific standards (including an ACL standard) before the site is transferred to the government for long-term custody.
4.4.4 Evaluation Findings If the staff review, as described in SRP Section 4.4, results in the acceptance of the Ground-Water Corrective Action Plan and compliance monitoring plans, the following conclusions may be presented in the TER.
NRC has completed its review of the ground-water corrective action and compliance monitoring plans at the uranium milling facility. This review included an evaluation using the review procedures in Section 4.4.2 and the acceptance criteria outlined in Section 4.4.3. The ground-water corrective action program should achieve the goal of returning hazardous constitu.:nt concentration levels in ground water to the concentration limits set as standards (Part 40, Appendix A, SD). The monitoring program will provide reasonable assurance that at the end of corrective actions the ground-water protection standard will not be exceeded.
The licensee has established a ground-water compliance strategy, that is acceptable for the site, which consists either of no remediation or active remediation, when contaminants are present at concentrations above background levels, MCLs, or ACLs. When active remediation is necessary, the remedial action design and implementation are acceptable. Tnc licensee has acceptably presented pumping / injection rates, treatment methods, equipment and maintenance requirements, and plans and schedules for constmetion, and has produced maps showing locations of remediation equipment. An analysis has been conducted that demonstrates: (1) the chosen active remediation system technology is appropriate for the site conditions;(2) design pumping rates are sustainable and will control migration of contaminants away from the site; and (3) the natural heterogeneity of the system has been acceptably accounted for in {
a conservative remediation strategy. The licensee has identified acceptable waste management practices. l Appropriate oversight by qualified engineers, State authorities, and national agencies has been {
accomplished. Institutional controls are appropriate for the site, including: (1) controlling access to the j site; (2) conducting periodic inspections; and (3) periodically monitoring restoration performance. The j monitoring program includes: (1) a description of QA procedures; (2) the number of monitoring wells and their locatic is; (3) a list of constituents that will be sampled, along with the sampling frequency for each monitored c, istituent; and (4) action levels for triggering enhanced monitoring or revisions to cleanup activities. Ne licensee has described an acceptable scheme for restoration and compliance i monitoring. An acceptable observational period for determining compliance has been established at i longer than 1 year. The licensee will sample ground water at the POC for all hazardous constituents of j concem. !
On the basis of the infomiation provided in the application and the detailed review conducted of the !
ground-water corrective action and compliance monitoring plans for the uranium milling facility, the staff has concluded that the plans are acceptable and are in compliance with Part 40, Appendix A, Criterion 5B, which requires NRC to establish a list of hazardous constituents, concentration limits, a POC, and a compliance period; Part 40, Appendix A, Criterion SC, which ;
provides a table of secondary concentration limits for certain constituents when they are present in j ground water above background concentrations; Pan 40, Appendix A, Criterion SE, which requires j licensees condncdng ground-water protection programs to consider the use of bottom liners, recycle of l
solutions and conservation of water, dewatering of tailings, and neutralization to immobilize hazardous NUREG-1620 4-40
constituents; Part 40, Appendix A, Criterion SF, which requires that where ground-water impacts due to seepage are occurring at an existing site, action must be taken to alleviate the conditions that lead to seepage, and ground water quality must be restored, including providing technical specifications for the scepage control system and implementation of a QA program; Part 40, Appendix A, Criterion 5G, which requires licensees to perform site characterization in support of a tailings disposal system proposal; Part 40, Appendix A, Criterion 5H, which requires steps be taken during stockpiling of ore to minimize penetration of radionuclides into underlying soils; Part 40 Appendix A, Criterion 7A, which provides for establishment of three types of monitoring systems: detection, compliance, and corrective action; and Part 40, Appendix A, Criterion 13, which provides a list of hazardous constituents that must be considered when establishing the list of hazardous constituents in ground water at any site.
If surface impoundments are to be used at the facility to manage 113.(2) byproduct material, the design of dikes used to construct surface water impoundments has been demonstrated to comply with Regulatory Guide 3.11, Sections 2 and 3 (U.S. Nuclear Regulatory Commission,1977), and therefore meet the requirements of 10 CFR Part 40, Appendix A, Criterion 5(A)5. In addition, because the impoundment dikes may meet the definition of a dam as given in the Federal Guidelines for Dam Safety, they are subject to the NRC Dam Safety Program, and to Section 215. " National Dam Safety Program, of the Water Resources Development Act of 1966" (optional, staff should add only if appropriate).
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4.4.5 References U.S. Nuclear Regulatory Commission,1977, " Design, Construction, and Inspection of Embankment Retention Systems for Uranium Mills", Regulatory Guide 3.11, Washington, DC: U.S. Nuclear Regulatory Commission, Office of Standards Development.
U.S. Nuclear Regulatory Commission,1980, " Operational Inspection and Surveillance of Embankment Retention Systems for Uranium Mill Tailings", Revision 1, Washington, DC: U.S. Nuclear Regulatory Commission.
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NUREG-1620 4-42
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5.0 RADON ATTENUATION AND SITE CLEANUP Reclamation Plan (RP) proposed activities at milling sites are required to meet appropriate standards for:
(1) tn. release of radon from tailings disposal cells after reclamation; (2) the cleanup of land and suildings at the processing sites; and (3) mdiation protection of workers and the public during mill tailings dispsal cell construction (reele.mation) and radioactive material cleanup activities. This chapter of the SRP establishes the requirements for NRC sta'f to perform and document review of the proposed designs for the attenuation of radon by use of soil covers, for the processing site (soil and structures) cleanup, and for the radiation safety controls and monitoring necessary to protect workers and the public during construction and cleanup activities.
The two main areas of review for radon ettenuation are the radiological and physical properties of the contaminated and cover materials and the application of the computer code or other model used for calculating the estimated long-term radon flux from the completed disposal cell. The areas of review for the site cleanup are the nature and extent of contamination, standards for cleanup, and verification procedures. The areas of review for radiation safety controls and monitoring for worker and public protection during disposal cell construction and site cleanup (including mill demolition) are the control of releases, the radiation exposure and environmental monitoring programs, and the contamination control program.
5.1 RADON ATTENUATION 5.1.1 Areas of Review The staff shall review the RP and its supporting documents to evaluate geotechnical and radiological information supporting the measurement and estimation of the properties (parameter values) of the tailings / contaminated material and radon barrier materials that affect the radon barrier design. The calculational rnethodology for estimating radon flux or the required barrier thickness shall also be examined.
For the radon barrier design of the tailings disposal cell cover, the licensee must demonstrate compliance with the NRC long-term radon flux standa:d. The staff shall review: (1) the bases, assumptions, and procedures for determining the parameter values of the tailings and radon barrier materials (such as the sampling and testing programs); (2) procedures for materials placement in the disposal cell, as presented in the RP construction specifications; (3) the description of the model (numerical or analytical) used to approximate the average long-term radon flux at the cover surface; and (4) if the standard computer codes (RADON, RAECOM) are not used, references for the methodology used to estimate the radon flux from the cover.
5.1.2 Review Procedures The radon barrier design, as presented in the RP, shall be reviewed along with the basic data supporting the design. The methodology used to calculate the exit radon flux through the tailings / cover system shall also be reviewed. Chapter 2 of this SRP provides review areas, procedures, and acceptance criteria for geotechnical information related to material properties. Reviews conducted using Section 5.1 shall be coordinated with those conducted using Chapter 2.
5-1 NUREG-1620
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i The reviewer shall evaluate the basis for selection of values fer tailings and cover material properties to ;
determine if the values are appropriate and will lead to a reasonably conservative estimate of the radon flux.
The scope and techniques used for site investigations shall be examined to ensure that the field investigation (boring, sampling, and surveying) and testing programs will provide the data necessary to I support the conclusions of the analyses. l The reviewer shall assess whether parameter values are consistent with anticipated construction I specifications and represent expected long-term conditions at the site.
The staff members assigned the health physics and geotechnical reviews shall coordinate the review of the radon attenuation design and analysis. The geotechnical information related to the physical characteristics of the contaminated and cover materials is discussed in Chapter 2 of this SRP. The proper;ies of the cover layers shall be considered in the context of their influence on the integrity (e.g.,
protection from erosion, biointrusion, and fn=eze-thaw events) and long-term moisture content of the radon barrier. Materials underlying the radon barrier are evaluated for stability so that cracking of the cover will not occur due to settlement or subsidence, as discussed in Chapter 2. The review shall also include the properties of off-site materials for those sites that have large volumes of off-site material that willbe placed in the disposal cell. l Specific parameter considerations to be evaluated by the reviewer are as follows:
(1) Long-Term Moisture-Determine whether adequate documentation of the basis for empirical relationships used in the analysis in the estimation of the long-term moisture content of the tailings material and the radon barrier material has been provided, and whether consideration has been given to meteorological and hydrological conditions at the disposal site, bulk density, type of material, and the influence of overlying material layers. The moisture content must be determined by accurate measured values or reasonably conservative estimates. The flux estimate must represent the average for periods of greater than one year but less than one hundred years; thus the emphasis on long-term conditions for parameter values.
(2) Material Thickness-Evaluate the estimate of the tailings thSkness determined from the total i tailings production and the areal extent of the tailings, or from data of representative bonngs, i I
for adequacy.
(3) Radon Diffusion Coefficient-Determine that documentation of the experirrental precision and accuracy for measurement of the diffusion coefficient for candidate cover soils and tailings material has been provided. If measurements are not available, the calculation of this parameter should incorporate the long-term moisture content of the material.
i (4) Radium Content-Determine that the value of the rad'um (Ra-226) activity concentration in l picoeuries per gram (pCi/g) within the tailings has been measured directly from representative !
tailings samples and other large-volume sources of contaminated material utilizing an l acceptable method. A value based on the grade of ore processed may be used if the tailings are j fairly homogenous for Ra-226 content and the value is supported by some Ra-226 data. If the j tailings were placed so that specific areas / levels in the pile contain slime tailings (higher Ra- i 5-2 I NUREG-1620
226 content than sand tailings), then Ra-226 values and the modeling should represent the layering or localization of the significantly elevated Ra-226 levels in the upper 12 feet. This is necessary because modeling higher concentrations of Ra-226 in the upper portion of the pile would result in a higher radon flux estimate than using a Ra-226 value averaged over a sample depth of 12 feet. Also, if large quantities of material with thorium (Th-230) levels significant higher than the Ra-226 levels are placed in the upper portion of the pile, the 1000-year Ra-226 i concentration (Ra-226 resulting the residual Ra-226 and that from the decay of Th-230) should be used for that layer of material in the modeling.
(5) Radon Emanation Coefficient-Review the method (s) used for determining the value of the emanation coefficient to ensure that those methods are appropriate and that the value is supported by adequate field and/or laboratory test records.
(6) Ambient Radon Concentration-Determine that a value of zero has been used for this parameter or that an adequately documented background value has been provided.
The reviewer shall determine that the RAECOM code, or an equivalent model, has been properly used. 1 The NRC equivalent code, RADON, may be used to validate the analysis provided by the licensee. The staff may conduct independent calculations using methods presented in the acceptance criteria below, if necessary.
The reviewer shall evaluate each parameter value, keeping in mind that the default parameter values are not always conservative, and then consider the set of parameter values. For example, considering the void ratio, the density, porosity, and moisture saturation values should be typical of the soil type. The radon flux model should result in a representative and a reasonably conservative (given the uncertainty in some values)long-term radon flux estimate.
A measured, not calculated, disposal cell average radon flux is required by Appendix A Criterion 6(2), l as soon as practical after placement of the radon barrier and Criterion 6(3) stipulates that verification of radon-222 release rates must be conductec' for each portion of the pile or impoundment as the final radon barrier for that portion is emplaced, when phased emplacement of the final radon barrier is included in the applicable RP. Criterion 6(4) requires reporting the results to the Commission within 90 dan of the completion of all testing and analysis. Therefore, the RP must stipulate if the radon barrier is to be placed in phases (months or years apart) or as a continuous operation.
5.1.3 Acceptance Criteria The analysis of the radon attenuation design will be acceptable if it meets the following criteria:
(1) The estimates of the material parameters used in the calculations are reasonably conservative, considering the uncertainty of the values, and the estimated soil cover thickness in the reclamation design is such that the calculated average long-term radon flux is reduced to a level that meets the requirement in 10 CFR Part 40, Appendix A, Criterion 6 (1).
The materials testing programs employ appropriate analytical methods, and sufficient and representative data and samples were collected to adequately determine material property 5-3 NUREG-1620
values for both the radon barrier and the contaminated materials, In the absence of sufficient j test data, conservative values are chosen and justification is provided. j l
(2) All parameter values are consistent with anticipated construction specifications and represent expected long-term conditions at the site. If freeze-thaw damage could occur in the upper ponion of the radon barrier, this layer should be modeled with the density reduced and the porosity increased by approximately nine percent.
For all site-specific parameters, supponing infonnation describing the test method and its precision, accuracy, and applicability is provided.
The basis for the parameter values and the methods in which the values are used in the analyses is adequately presented. Moisture-dependent parameter values are based on the estimated long-term moisture content of the materials at the disposal site (e.g., radon emanation coefficient).
The long-term attenuating capabilities of cover materials are adequately justified using the results of tests and experiments or relevant field experience with the same materials under {
environmental conditions similar to those at the site. 1
)
(3) Soil moisture values used in the design represent the long-term moisture content that I approximates the lower moisture retention capacities of the materials or anotherjustified, but j conservative value.
The licensee should compare estimated values for the long-term moisture content with present i in situ values to assum that the assumed long-term value does not exceed the present field l value derived from samples taken at a depth of 120 to 500 cm (3.9 to 16.4 feet), but not close to the water table. Also, the borrow site value for long-term moisture content should be co related j to the conditions at the disposal site.
The following methods are acceptable for estimating the long-tenn soil moisture, given the limitations stated above:
l l (a) Laboratory procedures ASTM D-3152 (fine-textured soils) and ASTM D-2325 l (coarse and medium-textured soils) conducted at 15-bar suction corresponding to the moisture content at which permanent wilting of plants occurs (Baver,1956); i and j (b) The empirical relationship (Rawls and Brakensick,1982) that predicts water retention values of a soil on a volume basis, represented by: J c = 0.026 + 0.005x + 0.0158y where c = predicted 15-bar soil water retention value x = percent clay in the soil l y = percent organic matterin the soil {
l NUREG-1620 5-4
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,l ..' l This method takes into consideration the particle-size distribution of the soil. i Clay particle sizes are defined here as those fm' er than 0.002 mm in diameter.
Organic content measurement is generally determined by reaction with hydrogen peroxide or by exposure to elevated temperature. Other tests, if adequately justified may be acceptable. {
The volumetric moisture coment value derived from this equation should be converted to a weight percentage for application in the RAECOM and RADON codes.
(4) The method for estimating the porosity of cover soils and tailings materials using the bulk I density and specific gravity given in Regulatory Guide 3.64, ' Calculation of Radon Flux Attenuation by Earthen Uranium Mill Tailings Cover" (NRC,1989) can be used.
Dry densities of the cover soils and tailings material determined from S'andard Proctor Test data (ASTM D-698) or Modified Proctor Test data (ASTM D-1577) are acceptable. Redon i barrier materials are usually compacted to a ndnimum of 95 percent of the maximum dry density as determined by ASTM D-698 or to a minimum of 90 percent of the maximum dry density as determined by ASTM D-1577. When the tailings materials are moved from one location to another, they are compacted to a minimum of 90 percent of the maximum dry density as determined by ASTM D-698. Field densities achieved following these specifications are used in the calculations. Altematively, if the pile is stabilized-in-place, the in siru bulk densities are used in the analyses.
Porosities am measured by mercury porosimetry or another reliable method, or a default value of 40 percent may be used if reference values for bulk density and specific gravity are employed as indicated in Regulatory Guide 3.64 (NRC,1989).
(5) The estimate of the tailings thickness is determined from estimates of total tailings production and the tailings areal extent, or from boring logs, soil samples, and gamma surveys of sufficient number.
Either the actual estimated thickness of a tailings source is used, or alternatively, a conservative f value of 500 cm (16.4 feet)is used (NRC,1989).
(6) The determination of the radon diffusion coefficient, D, represents the long-term properties of the materials and is based on measured values, or the physical characteristics of the soil are used with empirical correlations from previously measured values of the diffusion coefficient.
The radon diffusion coefficient of the cover soil is of central importance for determining the
} cover thickness necessary to achieve a given radon flux reduction.
The D value is most accurately determined from direct measurements, as described in Regulatory Guide 3.64, Section C.I.l.5 (NRC,1989). The soil should be tested at the design compaction density, with a range of moisture content values that bounds the lower moisture l retention capacity of the soil. The calculation of diffusion coefficient, based on moisture 5-5 NUREG-1620
{
saturation, and porosity, as proposed in Regulatory Guide 3.64, Section C.I.l.5 (NRC,1989) and an optional calcu!ation in the RADON code, is acceptable.
(7) Values for the radium activity concentration within the tailings (pCi/g) are measured directly from tailings samples and other large-volume sources of contaminated material by the radon equilibrium gamma spectroscopy, wet chemistry alpha spectrometry, or an equivalent procedure. If the tailings are uniform, estimation of Ra-226 activity from the ore grade, as discussed in Regulatory Guide 3.64 (Nuclear Regulatory Commission,1989), is acceptable.
Generally, tailings should be sampled at 60- to 90-cm (2- to 3-foot) intervals to a depth of 366 cm (12 ft), including representative sampling of slime tailings.
Since the disposal cell performance standard deals only with radon generated by the i contaminated material, it is acceptable to neglect the Ra-226 activity in the cover soils, provided the cover soils are obtained from background materials not associated with ore formations or other radium-enriched materials. Appendix A Criterion 6(5) requires that near surface (staff considers the upper two feet) cover materials be essentially the same radioactivity level as surrounding surface soils. If deeper cover layers contain elevated Ra-22.6 or Th-230, that material would need to be represented in the flux model.
(8) The emanation coefficient has been obtained by using methods for measuring provided in Nielson, et al. (1982) and properly documented, or otherwise set to the reasonably conservative j (for most soils) reference value of 0.35. 1 (9) The radon concentration above the top layer is either set to a conservative value of zero or a measured background value is used. The RAECOM and RADON computer codes also require the input of the precision number;'he level of computational error that is acceptable. A value of 0.001 is recommended for the precision. ,
(10) The use of one-dimensional, steady-state gas diffusion theory for calculating radon flux and minimum cover thickness is acceptable.
An acceptable analytical method for determining the necessary cover thickness to reduce radon flux to acceptable limits or to determine the long-term surface radon flux from the proposed ,
cover, is the computer code RAECOM (NRC,1984), and the compriable RADON code (NRC, f i
1989). The main difference between the two codes is that RADON does not have an optimization for cost-benefit. The staff will use the RADON code (NRC,1989) to verify the analysis. Other methods that estimate the average surface radon release from the covered tailings may be acceptable,ifit can be shown that these methods produce reliable estimates of ;
radon flux. j i
(11) The quality assurance program for parameter data is adequate and will be documented and f available for inspection.
5.1.4 Evaluation Findings If the staff review, as described in this section, results in the acceptance of the radon attenuation assessment, the following conclusions may be presented in the technical evaluation report (TER).
NUREG-1620 5-6
l 5 8 The staff has completed its review of the site disposal cell radon attenuation assessment at the uranium mill facility. This review included an evaluation using the review procedures in the Title II SRP, Section 5.1.2, and the acceptance criteria outlined in SRP Section 5.1.3.
The applicant has provided an acceptable radon attenuation design and staff evaluation determines that:
(1) estimates of all values of the material parameters lead to a reasonably conservative estimate of the long-term radon & - (2) material parameters are consistent with construction specifications and expected long-tm.u onditions; (3) the long-term attenuating capability of cover materials is justified using the results of relevant tests and experiments or conservative estimates;( 4) soil moisture values represent conservative long-term moisture retention capacities; (5) the method for es'imating the porosity of cover soils and tailings materials is based on the method in Regulatory Guide 3.64, (NRC,1989); (6) estimates of contaminated materials thickness are determined from estimates of total tailings production and the areal extent of tailings, or from borehole exploration, utilizing a sufficient number of data; (7) the radon diffusion coefficient of the cover soil is determined from direct measurements and NRC-approved ranges of soil densities using the long-term moisture saturation ratio or from calculations based on Regulatory Guide 3.64 (NRC,1989); (8) values for radium activity have been measured in the tailings and other large-volume sources of contaminated materials using the radon equilibrium method or by direct gamma spectroscopy (or equivalent procedure); (9) the emanation coefficient is obtained by either the equilibration method or the prediction method, or is set to a reasonably conservative value of 0.35; (10) the radon concentration above the cover has been set to a consersative value of zero or a measured background value; and (11) the method used for calculating radon flux and minimum cover thickness is based on the one-dimensional, steady-state gas diffusion theory.
Based on the information provided in the RP and the detailed review conducted of the radon attenuation assessment for the uranium mill facility, the staff has concluded that the radon attenuation design is acceptable and is in compliance with 10 CFR Part 40, Appendix A, Criterion 6(1),
which requires placement of an earthen cover (or approved altemative) over tailings or wastes at the end of the milling operations while providing assurance of control of radiological hazards for a 1000 years, to the extent reasonably achievable (but no less than 200 years); and which limits releases of radon-222 from uranium byproduct materials to the atmosphere so as not to exceed an average rate of 20 picoeuries per square meter per second (pCi/m2 -s) to the extent practicable throughout the effective design life and reduction of direct gamma exposure to background levels; and Criterion 6(5), which requires that near surface cover materials be essentially the same radioactivity as surrounding surface soils and not include waste or rock that contains elevated levels of radium.
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5.1.5 References Baver, L.D.1956. Soil Physics. New York, NY: John Wiley and Sons 283-303.
Nielson, K.K., and et al.1982. Radon Emanation Characteristics of Uranium Mill Tailings. Proceedings of the Symposium on Uranium Mill Tailings Management December 9-10,1982. Ft. Collins, CO: Colorado State University.
Nuclear Regulatory Commission.1984. Radon Attenuation Handbookfor Uranium Mill Tailings Cover Design. NUREG/CR-3533. Washington, DC: Nuclear Regulatory Commission.
Nuclear Regulatory Commission.1989. Calculation of Radon Flux Attenuation by Earthen Uranium Mill Tailings Covers. Regulatory Guide 3.64. Washington, DC: Nuclear Regulatory Commission, Office of Standards Development.
Rawls, WJ., and D.L. Brakensiek.1982. Estimating Soil Water Retention From Soil Properties. Journal of the irrigation and Drainage Division. Proceedings of the American Society of Civil Engineers 108(IR2).
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..' ,l 5.2 PROCESSING SITE CLEANUP 5.2.1 Areas of Review .
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Reclamation (decommissioning, closure) at milling sites must meet cleanup standards for radioactive l material, The ground water corrective action plan (see Chapter 4) is a separate document, as is the mill l decommissioning plan and the soil cleanup and verification plan. However, the reclamation plan must l summarize the e.xpected decommissioning activities, including characterization surveys, and make l commitments to provide detailed plans for NRC approval at least six months before decommissioning begins. i i
For site cleanup, the licensee must reduce the residual radium (Ra-226 )(Ra-228, if thorium (Th)-232 byproduct material is present) in soil to the concentration limits in Part 40, Appendix A, Criterion 6(6) in
! areas of the site that are not part of the disposal cell (e.g., contamination due to windblown material). The staff shall reMew the survey methods and data defining the nature and extent of contamination (key constituents, . rea, volume, and concentration); the cleanup criteria to be used at the processing site (including the Ra-226 background value, if not previously approved); the method (s) to be used to 1 I
monitor cleanup and to verify that the standards have been met; and the quality control program related to site r2eanup. The cleanup of mill-related radionuclides (1le.(2) byproduct material) other than Ra-226 (primarily umnium(U-nat) and Th-230), and cleanup of surface activity of structures, should follow NRC guidance until decommissioning criteria are incorporated into the regulations.
l To evaluate compliance with Criterion 6(7), the staff shall review licensee plans to control, minimize, or l eliminate the escape of nonradiological hazardous constituents (see Chapters 3 and 4) during the l reclamation and the postclosure period. The staff shall also evaluate licensee plans to ensure that closure j minimizes the need for continuing maintenance.
5.2.2 Redew Procedures l
l The staff shall determine that the background level of Ra-226 (and U-nat, Th-230, and Th-232, as l needed) in soilin the general area of the site has been determined using representative soil samples fmm t nearby uncontanunated areas that are geologically similar to the contaminated areas. The staff shall ensure that the licensee has committed to identifying contaminated areas and cleaning up these areas, using appropriate sampling and surveying methods and that the areal extent and depth of contamination j above the standards or guidelines in the soil have been/will be determined from representative and adequate sampling. The staff shall also determine that adequate testing has been planned to substantiate l that release for unrestricted use guidelines are met for structures, equipment, and materials that will not l be buried in the tailings disposal cell.
The staff shall ensure that the licensee's program to control, minimize, or eliminate post closure escape of nonradiological hazardous constituents, leachate, contaminated rainwater, or waste decomposition products to the ground water, surface water, or atmosphere is adequate. When a final decommissioning i plan is submitted, determine that it complies with Part 40.42g(4 and 5) and determine if the licensee has identified a location to keep the records of information important to the decommissioning as required by Part 40.36(f).
5-9 NUREG-1620 o
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5.2.3 Acceptance Criteria The plans or commitments for processing site cleanup will be acceptable if they meet the l following criteria:
- (1) The licensee has provided adequate plans to identify, clean up, and place within the disposal cell, all soils on and adjacent to the processing site that are in excess of the Ra-226 standards in Part 40, Appendix A, Criterica 6(6). Also, an appropriate site background Ra-226 value (different geological areas may need separate background values) has been proposed with supporting data.
The " Multi-Agency Radiation Survey and Site Investigation Manual" (NUREG-1575, NRC,1997) contains general principles of soil sampling, including determination of background, and gamma surveying. However, methods may need to be modified for application to large contaminated sites, e.g., composite sampling has been accepted. All areas of potential contamination are to be identified and sampled appropriately. Examples of such areas are temporary diversion ditches and evaporation ponds, process and storage areas, ore stockpile areas, transportation routes, and l operational air monitoring locations.
To ensure consistency of measurements, instrumentation used for pre-reclamation (characterization) surveys and analyses are similar to those used to determine background levels i and to provide verification data. The instmn ntation has the appropriate sensitivity. !
The soil mmpling density takes into consideration detection limits of sampling equipment and l analyses, the extent of expected contamination, and the size of the potentially contaminated area to l be sampled. Maps of the site areas with sampling grids and sample data by location are provided.
(2) The site cleanup plans in the RP are substantiated by the radiological characterization data and site history, or am otherwise justified. The plan includes adequate data collection oeyond the expected j excavation boundary, l (3) Characterization data or survey plans of potential residual thorium or uranium soil contamination are included for areas likely to be contaminated (e.g., ore pads, raffinate ponds, or the grizzly area).
If elevated levels of uranium or thorium are expected to remain after the Ra-226 criteria have been ;
met, the following guidelines for radionuclides other than Ra-226 are provided until the new NRC q decommissioning criteria are promulgated. j (a) The cleanup guideline for total uranium (U-238, U-235, and U-234, i.e., U-nat) or total thorium (Th-232 plus Th-228) is 10 pCi/g in the top 15 cm (6 inches) of soil and 30 pCi/g in subsequent 15 cm layers, or otherjustified criteria. The U-nat subsurface limit assumes that the Ra-226 levels are approximately background.
(b) One cleanup guideline for Th-230, based on the radium criteria, is 5 pCi/g in the top 15 cm of soil and 15 pCi/g in subsequent layers. An alternate criterion is to ensure that the total amount of Ra-226 (residual and from Th-230 decay) that would be present in 1000 years, meets the cleanup standard. For a deeply buried Th-230 .
deposit, it may be acceptable to determine that the amount of radon that could enter a 100 m2 structure built over that deposit would result in meeting the Environmental l
NUREG-1620 5-10 l l
Protection Agency's (EPA) radon progeny standard for habitable stmetures. Either of the altemate approaches must include an "as low as is reasonably achievable" l (ALARA) analysis. I (4) When the RP contains a proposal to leave suspected naturally occurring ore on the site, the licensee has provided appropriate procedures for its identification, such as use of U-238/Ra-226 ratios, or visual and/or chemical criteria. The staff has previously defined naturally occurring ore as in situ material that has not been processed. Licensees are not responsible, under NRC reguiations, for l the reclarnation of materialidentified as unprocessed (not crushed, refined, etc) ore. I (5) Final verification procedures are adequate to demonstrate compliance with the Ra-226 standards and the applicable guidelines for other radionuclides.
To reduce the cost of verification soil sampling and analysis, a statistical correlation between measured radium in the soil and gamma measurements at the same locations can be used to estimate radium concentrations from gamma measurements at other locations. If used, this correlation is based upon a least-squares regression analysis and uses Ra-226 concentrations of about I to 25 pCi/g (characterization data from the windblown tailings area) to reflect the area of concern. The RP contains, or commits to provide, the correlation graph with the 95 percent confidence limits.
The RP contains, or commits to provide, plans for post-reclamation verification measurements utilizing the same instrumentation and methods as those used to determine background levels of Ra-226 and the radium-gamma correlation. The proposed verification procedures will demonstrate that reclaimed arcan meet the radium concentration limit in Criterion 6(6) and comply with 10 CFR 40.42(j)(2) on the performance of the final radiation survey. A detailed quality assurance and quality control plan for verification includes the surveying, sampling, analysis, data collection, and data presentation (see NRC Inspection Procedure 87654). Any detailed informadon related to verification procedures presented elsewhere is appropriately referenced.
(6) The RP contains plans to clean any surface contamination, of equipment and structures to be released for unrestricted use, to levels below those specified in NMSS Policy and Guidance Directive FC 83-23 (NRC,1983)(based on NRC Regulatory Guide 1.86, Table 1). The plans indicate, for any habitable structure to be released, that the interior gamma levels will mee'. NRC guideline of 10 micro Roentgens per hour (above background). Any other contaminated material i designated for proper disposal.
(7) The RP contains a program to control, minimize, or eliminate post closure escape of nonradiological hazardous constituents, leachate, contaminated rainwater, or waste decomposition products to the ground water, surface water, or atmosphere is adequate (note that the assessment and review of nonradiological contamination of surface and ground waters are addressed in Chapters 3 and 4 of this SRP, respectively).
(8) The RP discusses records ofinformation important to the decommissioning as required by 10 CFR 40.36(f). These records would include documentation of spills or cleanup of contamination, drawings or descriptions of modification of structures in the restricted area, and locations of possible inaccessible contamination.
5-11 NUREG-1620
, . l 5.2.4 Evaluation Findings If the staff review, as described in this section, results in the acceptance of the processing site (soil and structures) cleanup, the following conclusions may be presented in the TER.
The staff has completed its review of the processing site cleanup plan for soil and structures at the uranium milling facility. This review included an evaluation using the review procedures in the Title II SRP Section 5.2.2, and the acceptance criteria outlined in SRP Section 5.2.3.
The licensee has provided an acceptable processing site cleanup plan, including: (1) appropriately substantiated site characterization data or plans in order to determine contaminated areas; (2) plans to clean up and place within the disposal cell all materials that are in excess of the standards and guidelines; (3) plans for postreclamation survey and sampling for verification that reclaimed areas meet radium concentration limits; (4) plans to clean surface cc:Jammation ot quipment and structures that are to be released for unrestricted use to acceptable levels; (5) appropriate pr aedures for the identification of suspected naturally occurring ore on the site, if needed; (6) adequate plans to cleanup residual uranium or thorium; and (7) plans to measure gamma levels in habitable buildings onsite to satisfy NRC guidelines.
Based on the information provided in the RP and the detailed review conducted of processing site cleanup for the uranium milling facility, the staff has concluded that the information is acceptable and is in compliance with 10 CFR Part 40, Appendix A, Criterion 6(6), which requires that the design requirements for longevity and control of radon releases apply to any portion of a licensed and/or disposal site unless such portion contains a concentration of radium in land, averaged over areas 1 of 100 square meters, which, as a result of byproduct material does not exceed the background levels by i more than: (i) 5 picoeuries per gram (pCi/g) of Ra-226 averaged over the first 15 centimeters (cm) below I the surface, and (ii) 15 pCi/g of Ra-226 averaged over 15-cm thick layers more than 15 cm below the !
surface. Also, the cleanup of other radionuclides in soil and surface activity on structures and equipment !
meet NRC guidance levels. In cases where the licensee has proposed an alternative to the requirements of Crite-ion 6(6) or the approved guidance, the staff has determined that the resulting level of protection j is equivalent to that required in Part 40.
5.2.5 References i Nuclear Regulatory Commission.1997. NRC Inspection Manual, Inspection Procedure 87654, l Uranium Mill Decommissioning Inspection.
Nuclear Regulatory Commission.1997. " Multi-Agency Radiation Survey and Site Investigation Manual," NUREG-1575, December 1997.
Nuclear Regulatory Commission.1983 " Guidelines for 15ontamination of Facilities and Equipment Prior to Release for Unrestricted Use or Termination of Liw . es for Byproduct, Source, and Special l Nuclear Material," Policy and Guidance Directive FC 83-23.
NUREG-1620 5-12 i 1
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l 53 RADIATION SAFETY CONTROLS AND MONITORING 53.1 Areas of Review I
Reclamation (decomtr.issioning, closure) activities (building demolition, contaminated soil cleanup, L tailings disposal cell stabilization) at mill sites will involve occupational, and possibly public, exposures j to radioactive materials that must be kept within the limits of 10 CFR Part 20. Surface restoration l (cleanup) and movement of contammated materials into the tailings cell (impoundment) and constmction of the disposal cell are potential sources of exposure to airborne contamination, radon gas, and external gamma radiation. The reviewer shall examine the radiological protection program for the construction
- phase of tailings disposal and cleanup operations and evaluate proposed measures to keep exposures as l low as itasonably achievable (ALARA) and in compliance with the requirements of Part 20. Existing l licensees will already have approved radiation protection programs for milling operations and general j decommissioning, and these licensees can reference the applicable parts of those programs for l reclamation activities. However, key components of these programs shall be reviewed to confirm their
, applicability to hazards unique to the reclamation working environment. Emphasis should be placed on I those aspects of the radiation protection program that have been changed, or that need to be changed to
- ensure safety during ieclamation. Consideration should also be given to any new activities that could increase hazards to general health and safety (e.g., cleanup in confined spaces, or removal of hazardous / flammable chemicals).
He staff shall review the RP and any supporting documents to evaluate the: (1) control of releases (minimize environmental emissions); (2) extemal radiation exposure monitoring program; (3) airbome radiation monitoring program for work areas; (4) bioassay program; (5) contamination control program; and (6) environmental monitoring program. The evaluation shall consider the exposures likely to occur due to the planned reclamation activities.
53.2' Review Procedures De staff reviews of the proposed safety controls and all monitoring progiants and procedures shall focus on determining whether the proposed programs are sufficient to meet the regulatory requirements. A licensee will already have an approved radiation safety program in place. Therefore, the focus of the review shall be to ensure that the RP addresses those aspects of worker protection that are unique and require special consideration in planning reclamation activities. In particular, any proposed changes to an ;
existing or planned radiation protection program shall be carefully reviewed. The RP should confirm the applicability of the existing radiation protection program to reclamation cleanup and construction activities or provide amendments to address new program needs. The RP should also confirm that the l environmental monitoring program is appropriate for the reclamation l
' phase.- 1 The staff shall determme whether the safety controls and monitoring procedures are sufficient to limit radiation exposures and radioactive releases during reclamation activities to the limits contained in 10 CFR Part 20, including ALARA levels. This determination shall be based upon review of the following parts of the radiation protection program.
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(1) Control of Releases 1 I
The staff shall determine whether the proposed systems and procedures (e.g., tailings stabilization, dust control) are sufficient to minimize environmental emissions from the tailings impoundment construction activities or structure demolition, taking into consideration important release mechanism uch as wind resuspension and surfaa erosion. The staff shall review the efforts taken to reduce . amount of resuspended material from the tailings area when such conditions are likely to exist at a site. Radon gas emanating from die tailings pile is also a radiation safety concern for workers and downwind offsite populations. However, because control of the source is not pos:ible during tailings recontouring or cleanup, the reviewer shall examine the means e.mployed to limit the worker inhalation hazard (i.e., limiting exposure time, or use of respirators) and to establish an acceptable environmental monitoring program for measuring offsite airborne concentrations. Also, liquid releases can be created by rainwater runoff. Therefore, the review of the reclamation plan shall include an evaluation of procedures for taking all exposum pathways into account and nor ensuring offsite exposures are ALARA.
(2) External Radiation Exposure Monitoring Program The review shall include the types of surveys conducted, criteria for determining survey locations, frequency of surveys, action levels, management audits, and corrective action requirements. The staff shall also review the program for personal monitoring (using film badges) including the criteria for placing workers in the program, the sensitivity and range of monitoring equipment, and
{
calibration methods, j (3) Airborne Radiation Monitoring Program for Work Areas The staff shall evaluate whether the proposed sarapling locations, frequencies, procedures and equipment are adequate to determine concentrations of airbome radioactive materials (including ,
radon) in work areas during construction, demolition, and cleanup activities. Action levels, audits, j and corrective action requirements shall also be evaluated.
(4) Bioassay Program 1 I
i The staff shall review the bioassay program proposed to confirm results from the airborne J radiation monitoring program and the exposure calculations. The staff shall review the criteria for including workers in the bioassay program, the types and frequencies of bioassays performed, and t the action levels applied to results. The staff shall determine whether the proposed bioassay 1 program is sufficient to protect employees. I I
1' (5) Contamination Control Program l The staff shall evaluate the occupational radiation survey program proposed to prevent employees l contaminated with radioactive materials from entering clean areas or leaving the site, to determine that it is sufficient to protect employees. This review shall include proposed housekeeping and
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cleanup requirements and specifications for clean areas to control contamination; frequency of surveys of clean areas; survey methods; and sensitivity, range, and calibration frequency of survey i
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NUREG-1620 5-14
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l equipment. Action levels for clean areas and for the release of materials, equipment, and work clothes from clean areas and/or the site shall be evaluated.
(6) Environmental Monitoring Program The staff shall determine whether the environmental monitoring program proposed for measuring concentrations and quantities of both radioactive and nonradioactive materials released to and in the environs of the proposed facility, are sufficient to protect employees and the public. Potential releases during disposal cell construction and cleanup activities will be primarily from resuspended tailings material and radon gas. The staff review shall focus on the frequency of sampling and analysis, the types and sensitivity of analyses, action levels, and corrective action requirements, and the required number of effluent and environmental monitoring stations (including criteria for l determining monitor station locations considering the reclamation work to be done). i 1
l l (7) Record keeping i The staff shall determine that the Record keeping requirements for the radiation protection program has been addressed; i.e., records of the provisions of the program and audits or other reviews of content and implementation are maintained for at least three years.
533 - Acceptance Criteria -
The radiation safety controls and monitoring for worker and public protection during reclamation will be I 1
acceptable if they meet the following criteria:
(1) The RP identifies the radiation safety concems that are unique to reclamation constmetion and site cleanup activities.
These concerns include characterization of radiation hazards associated with inhalation of resuspended tailings material or yellowcake, gamma expc a from working in close proximity to tailings, and inhalation of radon and daughter products emanating from tailings material in the work environment.
(2) The RP describes any changes to an existing or planned radiation safety program that would be necessary to ensure worker and public safety during reclamation activities. Programs that have not changed are referenced in the RP.
Applicable release mechanisms should be reviewed on a site-specific basis, taking into account the relevant climatic and environmental conditions. The staff should ensure procedures have been developed to verify that control strategies are effective.
l Changes might be necessary in the following areas: control of releases, extemal exposure j monitoring, airborne monitoring program, the bioassay program, contamination control, and environmental monitoring. In particular, the RP is acceptable if information on changes in eligibility criteria, locations and types of monitoring stations, and sampling / analysis frequencies is provided; and all modifications are adequately justified, and changed programs comply with the radiation protection requirements for workers and the public in Part 20.
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- i. I c All monitoring equipment is identified by type, with additional specification of the range, sensitivity, calibration methods and frequency, availability, and planned use. Staff should ensure that planned surveys of external radiation are consistent with the guidance in Regulatory Guide 8.30, " Health Physics Surveys in Uranium Mills" (NRC,1983) or that an acceptable justification has been provided for selecting an alternative approach. Plans for documentation of radiation exposures are consistent with the approach in Regulatory Guide 8.7, " Instructions for Recording and Reporting Occupational Radiation Exposure Data" (NRC,1982). Staff shall ensure that the applicant's monitoring program is sufficient to adequately protect workers from hazards of radiation resulting from the decay products of Ra-226.
(3) Any changes to an existing radiation protection program that would require a license amendment are identified.
(4) Regular wetting and/or phased stabilization efforts are used for control of windblown tailings material or yellowcake dust.
(5) Workers in close proximity to the tailings area will be equipped with personal dosimeters to assess gamma exposure until the licensee can demonstrate that annual external exposures are less than 10 percent of the limits in 10 CFR 20.1201(a).
(6) Changes to any existing or planned bioassay program for workers conform to the applicable parts of Regulatory Guide 8.22, " Bioassay at Uranium Mills" (NRC,1988) and Regulatory Guide 8.9 Revision 1 " Acceptable Concepts, Models, Equations, and Assumptions for a Bioassay Program" (NRC,1993), or an acceptable justification is provided for selecting an alternative approach.
Workers who are routinely exposed to tailings and yellowcake dust are included in the bioassay program when required by 10 CFR 20,1502, and sampling and analysis frequencies are sufficient to detect and take action against high intakes of uranium in the work place. The bioassay program specifies action levels that can be detected using standard bioassay methods. Participants in the program may include construction and cleanup workers who regularly work on or around the tailings impoundment where dust exposures are expected to be elevated from construction and cleanup activities.
(7) Changes to any existing or planned workplace airborne radiological monitoring program are consistent with applicable parts of Regulatory Guide 8.25, " Air Sampling in the Workplace" (NRC, 1992) and Regulatory Guide 8.30 (NRC,1983), or an acceptable justification is provided for selecting an alternative approach.
The RP includes one or more maps of the site thr
- indicate the location of samplers for airborne radiation and provides the criteria for determining sampling locations. Sampling locations are based, in part, on a determination of general airflow pattems (e.g., wind direction, topography) in areas where workers or the public could be present. All monitoring equipment is identified by type, with additional specification for the range, sensitivity, calibration methods and frequency, availability, and planned use. Staff should ensure planned surveys of airbome radiation are
.- consistent with the guidance in Regulatory Guide 8.30 (Nuclear Regulatory Commission,1983) or that an acceptable technicas,,ustification has been provided for selecting an alternative approach.
Plans for documentation of radiation exposures are consistent with the approach in Regulatory NUREG-1620 5-16
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Cuide 8.7 (NRC,1982). The staff shall ensure that the monitoring program is sufficient to provide adequate protection of workers from radon gas exposures to maintain compliance with the l exposure limits in Part 20. The air sampling program should be reviewed for consistency with
! relevant sections of Regulatory Guide 8.25 (NRC,1992).
(8) Changes to any existing or planned contamination control program are consistent with the guidance on conducting surveys for contamination of skin and personal clothing nrovided in Regulatory Guide 8.30 (NRC,1983).
l Standard procedures for a contamination control program (e.g., maintaining change areas and requiring personal alpha radiation monitoring prior to leaving radiation areas) should be referenced in the RP. Guidance on conducting surveys for contamination of skin and personal clothing is provided in Regult. tory Guide 8.30 (NRC,1983). This guidance refers specifically to yellowcake contamination; however, the principles aie generally applicable to workers exposed to tailings dust from construction and cleanup activities.
@) Changes to any existing or planned environn ental radiologier.1 monitoring are consistent with applicable parts of Regulatory Guide 4.14, " Radiological Fefluent and Environmental Monitoring at Uranium Mills" (NRC,1980), or an acceptable justification is provided for selecting an alternat've approach.
- Licensees ht.
- adequately considered site-specific aspects of climate and topography in l determining locations of offsite airborne monitoring stations and environmental sampling areas such that they are capable of detecting maximum offsite concentrations of windblown tailings material and contamination from any other significant transport pathways applicable to the site. In i
condacting their review, staff should refer to guidance in Regulatory Guide 4.14 (NRC,1980) whit.h contains information on determining locations, types, methods, frequencies, and analyses l that om sufficient to comply with the applicable Part 20 requirements for protection of the public i from offsite exposures. !
(10) The RP demonstrates that the proposed radiation protection program includes plans for i documentation of exposures to all monitoted workers and contractors and availability of exposure recontis in a single location for mspection.
! i (11) The proposed radiation protection program provides fer Record keeping that meets the requirements of 10 CFR 20.2102: at least annual review of the program content and implementation; and implementation of the ALARA requirements of 20.1101(d).
5.3.4 Evalustan Findings If the staff review, as described in this section, results in the acceptance of the radiation safety controls !
l and monitoring for worker and public protection du. 4g cell construction and site cleanup, the following conclusions may be presented in the TER.
l l 'lhe staff has completed its review of th ,ndiation safety controls and monitoring for y orker and public protection during construction and cleanup at the _ ._ uranium milling facility. This l
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. 1 review included an evaluation using the review procedures in the Title II SRP, Section 5.3.2 and the acceptance criteria outlined in SRP Section 5.3.3.
The licensee has provided an acceptable evaluation of radiation safety controls and monitoring required for worker and public protection during construction and cleanup activities, including: (1) identification of the radiatioa safety concerns that are unique to reclamation construction and site cleanup activities; (2) any nece Ery changes and associatedjustifications in an existing or planned radiation safety program that may melude the control of releases, external exposure monitoring, an airborne monitoring program, a bioassay program, contamination control, and environmental monitoring; (3) identification and discussion of any changes in an existing radiation protection program that would require a license amendment; (4) control of potential contamination from windblown tailings by regular wetting and/or phased stabilization; (5) equipping workers in close proximity to the tailings area with personal dosimeters to assas gamma exposures until it is demonstrated that annual extemal exposures are less than 10 percent of the limits in 10 CFR 20.1201(a); (6) changes to any existing or planned bioassay pmgram for workers to conform to applicable guidance or an acceptable justification for using an alternative approach; (7) changes to any existing or planned workplace airborne radiological monitoring program to conform to applicable guidance or an acceptable justification for using an alternative approach; (8) changes to any existing or planned contamination control program to conform to applicable guidance or an acceptable justification for using an altemative approach; (9) changes to any existing or planned environmental radiological monitoring program to conform to applicable guidance or an acceptable justification for using an altemative approach; and (10) plans for documentation of exposures to all monitored workers and contractors and for providing availability of these exposure records for )
inspection at a single location. i Based on the information provided in the RP and the detailed review conducted of the radiation safety controls and monitoring for worker and public protection during construction and cleanup for the uranium milling facility, the staff has concluded that the radiation controls and monitoring programs are acceptable and are in compliance with 10 CFR 20.1101, which requires I development, documentation, and implementation of a radiation protection program ensuring compliance with Part 20 requirements and the use of procedures and engineering controls to achieve occupational and public doses that are ALARA, and Part 40, Appendix A, Criterion 8, which requires implementation of control measures to limit dust emissions from tailings that are not covered by standing liquids, to include wetting or chemical stabilization. [This requirement may be relaxed for tailings impoundments ,
that have surfaces that are sheltered from wind exposure (i.e., below grade) or that have an interim l cover.]
5.3.5 References Nuclear Regulatory Commission.1980. Radiological Effluent and Environmental Monitoring at Uranium Mills. Regulatory Guide 4.14, Revision 1. Washington, DC: Nuclear Regulatory Commission, Office of Standards Development.
Nuclear Regulatory Commission.1982. Instructions fr- Recording and Reporting Occupational Radiation Exposure Data. Regulatory Guide 8.7, Revision 1. Washington, DC: Nuclear Regulatory Commission, Office of Standards Development.
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Nuclear Regulatory Commission.1983. Health Physics Surveys in Uranium Mills. Regulatory Guide 8.30. Washington, DC: Nuclear Regulatory Commission, Office of Standards Development.
Nuclear Regulatory Commission.1988. Bioassay at Uranium Mills, Revision 1. Regulatory Guide 8.22.
l Washington, DC: Nuclear Regulatory Commission, Office of Standards Development.
Nuclear Regulatory Commission.1992. Air Sampling in the Workplace. Regulatory Guide 8.25, Revision 1. Washiagton, DC: Nuclear Regulatory Commission Office of Standards Development.
Nuclear Regulatory Commission.1993. " Acceptable Concepts, Models, Equations, and Assumptions for a Bioarsay Program. Regulatory Guide 8.9, Revision 1. Washington DC: Nuclear Regulatory l Commission l
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APPENDIX A GUIDANCE TO THE NRC STAFF FOR REVIEWING HISTORICAL ASPECTS OF SITE PERFORMANCE FOR LICENSE RENEWALS AND AMENDMENTS s
APPENDIX A GUIDANCE TO THE NRC STAFF FOR REVTGVING HISTORICAL ASPECTS OF SITE PERFORMANCE FOR LICFsNSE RENEWALS AND AMENDMENTS For license renewals and amendments, the historical record of site operations provides valuable information for evaluating the licensing actions. Following are specific areas in which a compliance history or record of site operations and changes should be provided for review:
Amendments and changes to operating practices or procedures License violations identified during Nuclear Regulatory Commission or Agreement State site inspections Excursions and resultant cleanup histories or status Exceedences of any radiation exposure, contamination, or release limits Exceedences of any nonradiation contaminant exposure or release limits Changes to any site characterization information important to the evaluation of reclamation l plan, including site location and layout, uses of adjacent lands and waters, meteorology, seismology, the geologic or hydrologic setting, ecology, background radiological or nonradiological characteristics, and other environmental features
(
Effects of site operations, including data on radiological and nonradiological effects, accidents, and the economic effects of operations Changes to factors that may cause reconsideration of alternatives to the propaM acnon Changes to the economic costs and benefits for the facility since the last application If, after a review of these historical aspects of site operations, the staff concludes that the site has been operated so as to prr,tect health, safety, and the environment, and that no unreviewed safety-related concerns have been identified, only those changes proposed by the license renewal or amendment or application should be reviewed, using the appropriate sections of this Standard Review Plan. Aspects of the facility and its operations that have not changed since the last license renewal or amendment should not be reexamined.
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APPENDIX B GUIDANCE TO THE NRC STAFF ON THE USE OF STANDARD STATISTICAL HYPOTHESIS TESTING 1
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APPENDIX B GUIDANCE TO THE NRC STAFF ON THE USE OF STANDARD STATISTICAL HYPOTHESIS TESTING Hypothesis Testing Statistical hypothesis testing methods used for: (1) establishing background water quality; (2) establishing groundwater protection standards for compliance monitoring; (3) determining the extent of groundwater contamination; and (4) establishing the groundwater cleanup goals, are described in this appendix.
The following discussion on the use of standard statistical hypothesis testing is adapted from Environmental Protection Agency (EPA) guidance 1989a, b; 1993) and statistics texts (Haan,1977; Gibbons,1994; Abramson et al.1988). The information presented here is referenced in other chapters of this SRP. Statistical hypothesis testing methods are used for: (1) establishing background water quality; (2) establishing groundwater protection standards for compliance monitoring; (3) determining the extent of groundwater contamination; and (4) establishing cleanup standards.
A statisticahest of a hypothesis is a rule used for deciding whether a statement (i.e., null hypothesis)
I should be rejected in favor of an alternative statement (i.e., alternative hypothesis). The null hypothesis can be expressed as: "There is no difference between background and onsite water quality." The alternative hypothesis can be expressed as: "Onsite contaminant concentrations are above background." l Because the concem lies only with concentrations of contaminants that are above background, this i expression of the altemative hypothesis implies a one-tailed test of significance. Presumably, concentrations of any constituent in concentrations below background water quality pose no excess risk.
Two types of error are possible in hypothesis testing: the null hypothesis may be rejected when it is true (Type I error or false positive) or it may be accepted when it is false (Type II error or false negative). An example of Type I error in the context of this discussion would be to conclude that ground-water has been contaminated from mill tailings when, in fact, it has not. Thus, Type I error could result in unnecessary remediation. Conversely, Type II error could result in contaminated water being left untreated. In customary notations, a (alpha) denotes the probability of the hypothesis test leading to a Type I error, and p (beta) denotes the probability of Type II error. Most statistical comparisons refer to the value 100a (in percent) as the level of significance. For example, if a = 0.01, there is a 1 percent chance of concluding that concentrations of contaminants are higher than background when they actually ale not.
Before any groundwater monitoring criteria are determined, the implications of each type of error are considered. Clearly, if a Type I error is made, the error tends to favor protection of human health and the environment, but will result in unnecessary expenditure of capital. Thus, a higher value of a is more conservative when considering risk to human health and the environment; howeve.r, values that are too B-1 NUREG-1620
high could result in unrealistic restoration goals with I ttle or no reduction in risk.
In testing hypotheses, the value for a is usually specified a priori. The value of p, however, is not known unless the true parameter values being tested (e.g., the true background contaminant levels) are already known; this, of course,is rarely the case, as the parameter values are only estimated on the basis of a limited number of samples. In general, as the value of a decreases, the value of p increases. The value of p can also be reduced by ensuring that an adequate number of samples are obtained. Because an accurate assessment of background water quality is crucial to all subsequent monitoring efforts, the number of background samples collected should be sufficient to accept or reject the null hypothesis with a specified a.
Generally, the likelihood of Type II error can be sufficiently limited with a sample size that includes a minimum of six randomly distributed monitor well locations to capture spatial variations, and four sample periods to capture temporal variations. The Nuclear Regulatory Commission finds it acceptable to space sampling a' ast 2 weeks apart to capture temporal variations. Licensees are expected to take samples at greater intervals if seasonal variations are expected to be significant. The term " sample" is used to refer to the set of concentration measurements for each sampled constituent.
t Thus, a single sample will contain at least 24 concentration measurements for each water quality -
parameter (constituent) of concem.
Ideally, background water quality is determ.ned at a uranium mill site before the commencement of any milling operations. Background samples are collected both onsite and offsite. In the event that a mill site may have conducted operations before the determination of background water quality, then background may have to be determined using only offsite, upgradi:nt samples. Once the background sample has been collected, some statistical analysis is required. The statistical analysis process can be divided into five major steps, and these steps are common to any data that are being analyzed. These steps will be ;
referred to extensively in later sections. They include the following:
(1) Checking for the validity of statistical assumptions (2) Handling nondetects (3) Analysis of variance (ANOVA) test (4 Analysis for statistical intervals (5) Strategies for multiple comparisons From the regulatory viewpoint, EPA recommends (Environmental Protection Agency,1993) that a specific statistical analysis should be performed to meet the groundwater protection standards. The following table, Table B.I. summarizes the use of statistical methods.
9 NUREG-1620 B-2
i Table B.1. Summary of Statistical Methods Compound Type of Comparison Recommended Method Any compound in background Background versos compliance well ANoVA Tolerance limits Prediction intervals Intra-well Control charts ACUMCL specific
- Fixed standard Confidence intervals Tolerance limits Synthetic Many nondetects in data set Cohen's adjustment Aitchison's adjustment
' ACL- Alternate Cmcentration Limits; MCL-Maximum Concentration Limits.
Checking for the Validity of Statistical Assumptions
'Ihe inherent assumption with all parametric statistical methods described in Table B.1 is that the data being analyzed are normally distributed or can be transformed into a normal distribution. This assumption should be verified by testing the normality of data. If the measured data are not normally distributed, the log of measured data should be tested for lognormal distribution. In environmental compliance, measured concentration data will be most likely to be lognormally distributed. If the background sample exhibits variability in constituent concentrations over several orders of magnitude and a high positive s1 uv, then log-transformation of the sample data may be necessary to obtain a distribution that mor; asely approximates normal. If the background sample exhibits a bimodal distribution due to zon of distinct water quality, it may be necessary to split the sample to obtain two normally distributed rarnples-one for each zone of water quality. When a sample is split, it may be necessary to obtain additional measurements from new sample locations, to obtain the minimum of six measurements for each distinct water quality zone. If bimodal distributions are encountered because of temporal variations, it is acceptable to evaluate the measurements collected during each sample period separately; this would result in four background samples, each containing a minimum of six measurements for :ach constituent. Whenever a bimodal distribution is encountered, the reviewer shr.ll verify that it is caused by changes in natural variations in water qcality, and not caused by the presence ofcontammation.
Summary statistics are calculated for the background sample. The two most important statistics for i
hypothesis testing are the mean and standard deviation. For normal distributions, the mean represents the arithmetic mean; for log-normal distributions, the mean represents the geometric mean of the sample data. The various methods that can be used for testing the normality or lognormality of data are:
Probability Plots, Coefficient of Ske.vness, Shapiro-Wilk test, Shapiro-Francia test, and Probability Plot Correlation Coefficient (Environmental Protection Agency,1993). If the assumption oflognormality is valid, further statistical analyses should be performed. However, if the data are neither normal nor
! lognormal, a non-parametric technique should be used.
Handling Nondetects l
If fewer than 15 percent of all samples are nondetect, replace each nondetect by halfits detection or
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quantitation limit. Care should be taken in choosing between the method detection limit (MDL) and the physical quantitation limit (PQL)(Environmental Protection Agency,1993). The nondetects are reported as " undetected" or " detected but not quantified" and with or without an estimated concentration.
If an estimated concentration value is given, the value should be used for statistical analysis. Otherwise, nondetects should be substituted by one-half of PQL since PQL is a better representative cf actual laboratory conditions than MDL. After this correction, the data can be analyzed by any parametric approach, (e.g., ANOVA or statistical interval).
If more than 15 percent but fewer than 50 percent of all samples are nondetects, either Cohen's adjustment or Aitchison's (Environmental Protection Agency,1993) adjustment should be applied. If more than 50 percent but fewer than 90 percent of the samples are nondetects, nonparametric statistical intervals, for exarrrple, Poisson Prediction Limit (Environmental Protection Agency,1993), should be used.
Analysis of Variance (ANOVA) Test The ANOVA test is used to compare concentration data from several compliance wells with concentration data with background wells. This method is used to test for the statistically significant evidence of higher mean concentration in compliance wells than the background concentration as i provided by background wells. ANOVA is best used for comparisons between wells that are hydraulically upgradient of a site and those that are downgradient from the site. The parametric ANOVA technique makes two key assumptions: (1) that the data residual are normally distributed and (2) that the group variances are approximately equal. If any of these assumptions are not valid, it is recommended that a nonparametric approach, such as the Kruskal-Wallis test or the Wilcoxon Rank-Sum test (also known as the Mann-Whitney U test)( Environmental Protection Agency,1993), is used in analyzing the data. The Kruskal-Wallis test is used when three or more well groups are compared, however, for comparing one compliance well with one background well, the Wilcoxon Rank-Sum test should be used.
A non-pnametric ANOVA based on ranks, followed by muluple comparison procedures can be used to identify statistically significant evidence of contamination. The method includes estimation and testing of the contrasts between each compliance well median and the background median levels for each constituent.
Analysis for StatisticalIntervals There are three types of statistical intervals that are most commonly constructed from the data:
confidence intervals, tolerance intervals, and prediction intervals. The interpretation and use of each of these intervals is quite distinct. A confidence interval is a random interval that is designed to contain the specified population parameter with a designated level of confidence or probability, denoted as 1 -a. A confidence interval should be used only in two situations for groundwater data analysis:
(1) when directly specified by permit or (2) in compliance monitoring, when downgradient samples are being compared with a fixed groundwater protection standard, (e.g., Part 40 or ACLs). In other cases, it is usually desirable to use either tolerance or prediction intervals.
A tolerance interval, also random interval,is designed to contain a designated proportion of population with a certain confidence level. Two coefficients are associated with any tolerance interval: coverage and tolerance coefficients. Coverage is the proportion of the population that the interval is supposed to contain and the tolerance coefficient is the degree of confidence with which the interval reaches the NUREG-1620 B-4
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specified coverage. A tolerance interval with coverage of G percent and a tolerance coefficient of 99 percent are constructed to contain, on average,99 percent of the distribution with a probability of 99 percent. Since a tolerance interval is designed to cover all but a small percentage of the population's measurements, observations should rarely exceed the upp wierance limit when testing small sample size. The tolerance intervals can be used in detection momtonng when comparing compliance data with background values. They can be used in compliance monitoring when comparing compliance data with certain fixed standards, (e.g., Part 40 or ACLs).
A one-sided test of significance is used to determine the upper limit of the range of background concentrations. This is also known as the tolerance limit method.This lirnit is given by U=x+t,ys, y (4.1) where E is the mean value determined for the background sample; s,is the standard deviation of the backgrour.d sample; 1,,is 7 the t-statistic for y = (1-a); and v = (n- 1) of degrees of freedom, where n is the number of background measurements for each constituent. Values for t-statistics are obtained from t-tables that can be found in most basic statistics textbook.s. The value of U for each constituent is interpreted as the maximum concentration of that constituent that may be present in any single monitor well without concluding that the constituent concentration is above the range of reasonable background concentrations.
Equation (4.1) is used for detemsining whether constituent c uentrations meet the background criterion in any single well. However, it is often the case that a licensee wishes to demonstrate compliance with ,
the background criterion by using well field average concentrations for each constituent. That is, while a concentration in one or more wells may exceed background, the water quality of the aquifer, on average, meets the background criterion. NRC finds this approach to be acceptable; however, it necessitates a change to Eq. (4.1). Rather than the standard deviation of the single background sample ( s,), the standard deviation of the sample average ( s,) must be used. Normally, this would require that at least ;
six background camples be collected, the mean of each sample be determined, and a calculation be made of the standard deviation for these background sample means. However, it is rarely the case that enough background samples are collected to calculate s-j directly. For these purposes, s- can be approximated by the equation s*
(4.2) sg= E5 l 'A prediction 'r* val is a statistical interval calculated to include one or more future observations from the same population with a specified confidence. In groundwater monitoring, a prediction interval appmach can be used in two ways: (1) to compare compliance well data with background well data and (2) to make intrawell comparisons for an uncontaminated well. If future observations are found to be in the prediction interval, then there is no contammation. However, if the measured concentration is above the prediction interval's upper limit, it is statistically significant evidence of contamination.
Another commonly used technique for intrawell comparison is contml charts (Environmental Protection Agency,1993). The control chart method is recommended for uncontaminated wells only. This is an B-5 NUREG-1620
effective technique to monitor contamination over time. The control charts should be constructed with data that am free from seasonal v uiability. It is important to note that the control charts should not be used for wells that show evidence of contamination or an increasing trend.
Strategies for Multiple Comparisons When more than one statistical test is performed during any monitoring period, the problem of multiple comparisons needs to be addressed. These comparisons can arise from the fact that multiple compliance wells were tested against multiple background wells for several contaminants. Usually the same statistical test is performed in every comparison, each test naving a fixed level of confidence (1 -a), and ,
a corresponding false positive rate, n.
The selection of an a value is not arbitrary: the consequences that would result from Type I error murt be considered. In most cases, Type I error favors protection of human health and the environment, but results in unnecessary expenditure of capital for restoration. Thus, a higher value of a is more conservative when considering risk to human health and the environment; however, values that are too high could result in unrealistic cleanup standards, with little or no reduction in risk. EPA recommends an a-value of 0.05 (Environmental Protection Agency,1989a). The number of contaminants present at a site should also be considered when selecting a value for a. For example, the EPA-recommended a- t value of 0.05 translates to a 1-in-20 chance of Type I error. However, if 20 constituents are being evaluated for cleanup standards, and each has a 1-in-20 chance of Type I error, the result is a 64 percent chance that at least one Type I error will occur. In such cases, using an a-value of 0.05 is likely to result i in unnecessary restoration. However, a-values lower than 0.01 should not be used at sites where public water supplies or sensitive environmental areas may be threatened by contamination.
Once a background sample has been properly collected and analyzed for each constituent of concern, it is then possible to conduct hypothesis testing for establishing cleanup standards and groundwater 1 protection standards, and for determining the extent of any existing contamination. The review should confirm that the statistical method used complies with the following, as appropriate:
(1) . The statistical method used to evaluate groundwater monitoring data is appropriate for the distribution of chemical parameters or hazardous constituents. If the distribution of the chemical parameters or hazardous constituents is shown by the ower or operator to be inappropriate for a normal theory test, then the data are transformed or a distribution-J free theory test is used. If the distributions for the constituents differ, more than one i statistical method is needed. j i
(2) If an individual well comparison procedure is used to compare an individual compliance l well constituent concentration with background constituent concentrations or a j groundwater protection standard, the test is done at a Type I error level no less than 0.01 i for each testing period. If a multiple comparisons procedure is used, the Type I error rate for each testing period is no less than 0.05; however, the Type I error of no less than 0.01 for individual well comparisons is maintained. This does not apply to tolerance intervals, '
prediction intervals, or control charts.
(3) If a control chart approach is used to evaluate groundwater monitoring data, the specific type of control chart and its associated parameter values are proposed by the licensee.
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I (4)' If a tolerance interval or a prediction interval is used to evaluate groundwater monitoring
- data, the levels of confidence and, for tolerance intervals, the percentage of the population that the interval mmt contain, are proposed by the licensee. These parameters are determined afto considering the number of samples in the background database, the data distribution, and the range of the concentration values for each constituent of concern.
(5) The statistical method accounts for data below the limit of detection with one or more statistical procedures that are protective of human health and the environment. The limit of detection that is used in the statistical method is the lowest concentration level that can be reliably achieved, within speciGed limits of precision and accuracy, during routine laboratory operating conditions that are available to the facility.
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! If necessary, the statistical method includes procedures to control or correct for seasonal
.(6).
and spatial variability as well as temporal correlation in the data.
References Abramson, L.R., et al.,1988, " Statistical Methods for Nuclear Material Management," Nuclear Regulatory Commission, NUREG/CR-4604,1988.
Gibbons, R.D.,1994, Statistical Methodsfor Groundwater Monitoring. New York, NY: John Wiley &
Sons,Inc.,19Si ,
Haan, C.T.,1977, Statistical Methods in Hydrology, Ames, IA: Iowa State University Press,1977.
Environmental Protection Agency,1989a, Statistical Analysis ofGround-WaterMonitoring Data at RCRA Facilities, Interim Final Guidance, EPAl530/SW-89/026,1989. \
Environmental Protection Agency,19896, Risk Assessment Guidancefor Superfund," Vol. I, Human
' Health Evaluation Manual (Interim Final 9/29/89), OSWER Directive 9285.7-01a,1989.
Environmental Patection Agency,1993, Statistical Training Coursefor Groundwater Monitoring Data Analysis, EPA /530-R-93-003,1993.
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I APPENDIX C OUTLINE RECOMMENDED BY THE NRC STAFF i FOR PREPARING SITE-SPECIFIC FACILITY RECLAMATION AND STABILIZATION I COST ESTIMATES FOR REVIEW l
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i APPENDIX C OUTLINE RECOMMENDED BY THE NRC STAFF !
FOR PREPARING SITE-SPECIFIC FACILITY RECLAMATION AND STABILIZATION COST ESTIMATES FOR REVIEW l As required under Criteria 9 and 10 of 10 CFR Part 40, Appendix A, the licensee shall supply sufficient l information for the Nuclear Regulatory Commission to verify that the amount of coverage provided by f the financial assurance accounts for all necessary activities required under the license to allow the license I to be terminated. Cost estimates for the following activities (where applicable) should be submitted to NRC with the initial license application or reclamation plan, and should be updated annually as specified in the license. Cost estimates must be calculated on the basis of completion of all activities by a third party. Unit costs, calculations, references, assumptions, and equipment and operator efficiencies, etc.,
must be provided.
The detailed cost information necessary to verify the cost estimates for the preceding categories of closure work is described in the recommended outline that follows.
l (I) Facility Decommissioning This includes dismantling, decontamination, and disposal of all stmetures and equipment. This may be done in two phases. In the first phase, only the equipment not used for groundwater restoration (including the stability monitoring period) is removed. Well plugging and removal of the remaining equipment would be performed in a second phase, after the approved completion of groundwater restoration. The buildings may be decontaminated and released for unrestricted use.
l (A.) Salvageable building and equipment decontamination. For each bmiding or piece of equipment listed, the following data should be provided:
(1) Labor for dismantling and decontamination (a) Mar,-hours and categories oflabor (b) Average hom.. r each category (c) Total labor cost (oenefits, insurance, etc., and all labor overhead must be included here or calculated on the basis of total project labor).
I l (2) Equipment and material for dismanUMg and decontamination
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! (a) Itemization of equipment and material to be used for decontamination l
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(b) Itemized cost for material and equipment cost per hour listed in (a) above
. (equipment costs must include hoerly operating, ownership, and overhead expenses)
(c) Operating hours for each piece of equipment
-(d) Total cost of equipment and material (B) Nonsalvageable building and equipment disposal:
(1) List of major categories of building and equipment to be disposed of and their corresponding quantities:
(a) Stmotures (list each major) metric tons [ tons (short)] of material and building volume cubic meters (cubic yards)
(b) Foundation concrete [ cubic meters (cubic yards))
(c) Process equipment [ metric tons (tons (short)]
(d) Piping and insulation (lump sum)
(e) Electrical and instrumentation (lump sum).
(2) Unit cost of disposal for each item above (include equipment, labor, material, transportation, and disposal costs).
(3) List each chemical solution within the mill area vi state how it will be disposed f of along with the associated cost of disposal.
(4) Total cost.
(c) Restoration of contaminated areas (ore storage pad, access roads, process area, affected groundwater, evaporation pond residues, etc.).
Removal and disposal of 11(c)2 byproduct material-In Part 40, Appendix A, Criterion 2,it is rquhod that these materials are to be transported and disposed of at a licensed tailings area or licensed disposal site. The quantity of material to be removed, the distance to the disposal site, and the fees charged by the receiving facility are important considerations in determining the costs of disposal.
a Reclamation 'Ihis entails recontourmg the tailings disposal cell and evaporation ponds and placing top soil or other materials acceptable to NRC. Reclamation may also include revegetation.
(1) Removal:
NUREG-1620 C-2
(a) Area, depth, and quantity of material to be removed [ area, meters (feet), and cubic meters (cubic yard)-or size of liner if appropriate]
(b) Unit cost (include excavation, loading, transportation, and deposition)
- (c) Total cost (equipment and labor).
(2) Revegetation:
I (a) Area to be revegetated (acre).
(b) Unit cost (include fill material replacing topsoil, and revegetation cost).
(c) Total cost (equipment, labor, and materials).
(II) Groundwater Restoration and Well Plugging he most cases, groundwater restoration consists of groundwater sweeping and water treatment, with partial reinjection. The capital costs are for water treatment equipment, costs of operation, maintenance, and replacement filters for the restoration phase.
(A). Method of restoration (B) Volume of aquifer required to be restored, area and thickness of aquifer, number of required pumping cycles, and cycling time ,
(C) Equipment associated with aquifer restoration (e.g., reverse osmosis unit)
(D) Verification sample analysis:
(1) Number of samples i
(2) Unit cost for sample collection and analysis (per sample)
(3)- Total cost for verification sample analysis.
(E) Wellplugging:
(1) Number of drillholes to be plugged (2) Depth and size of each drill hole (3) Material to be used for plugging including acquisition, transportation, and Pl ugging (4) Total cost for well plugging.
C-3 NUREG-1620 L
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a a (F) Total cost for groundwater restoration.
(III) Radiological Survey and Environmental Monitoring Radiological Survey-Surveys and soil samples for radium in areas to be released for restricted use. Soils around the tailings disposal cell, evaporation ponds, and process buildings should be analyzed for radium content. A gamma survey of all areas should be made before release for unrestricted use. All equipment released for unrestricted use should be surveyed and records maintained.
(A) Soil samples for radium (B) Decommissioning equipment and building smear samples (C) Gamma survey (D) Environmental monitoring: Costs oflabor, materials, and analysis for continuation of environmental monitoring program throughout reclamation.
(E) Total cost:
(1) Number of each kind of sample listed above (2) Unit cost for sample and analysis (price per sample)
(3) Total cost for radiological survey.
(IV) Project Management Costs and Miscellaneous Itemize estimated costs associated with project management, engineering changes.
mobilization costs, legal expenses, power costs during reclamation, quality control, radiological safety costs, etc.
(V) Labor and Equipment Overhead, Contractor Profit Overhead costs for labor and equipment and contractor profit may be calculated as separate items or loaded into hourly rates. If included in hourly rates, the unit costs must identify the percentages applied for each area.
(VI) Contingency The licensee should include a contingency amount to the total cost estimate for the final site closure. The staff currently considers a 15 percent contingency to be an acceptable minimum amount.
NUREG-1620 C-4 l
c (VIII) Adjustments to Surety Amounts The licensee is required by Part 40, Appendix A. Criterion 9, to adjust cost estimates annually to account for inflatier. and changes in reclamation plans. The submittal should be in the form of a request for amendment to the license.
(A) Adjustments for inflation: The licensee should submit a revised surety incorporating adjustments to the cost estimates for inflation 90 days before each anniversary of the date on which the first reclamation plan and cost estimate was approved. The adjustment should be made using the inflation rule indicated by the change in the Urban Consumer Price Index published by the U.S. Department of Labor, Bureau of Labor Statistics.
(B) Changes in Plans:
(1) Changes in the process such as size or method of operation (2) Licensee-initiated changes in reclamation plans or reclamation / decommissioning activities performed (3) Adjustments to reclamation plans required by NRC.
(4) Proposed revisions to reclamation plans must be thoroughly documented and cost estimates and the basis for cost estimates detailed for NRC review and approval. Where a licensee is authorized by NRC to secure a suiety arrangement with the State, no reduction to the surety r. mount shall be initiated without prior NRC approval. Copies of all correspondence relating to the surety between the licensee and the State shall be provided to NRC. If authorized by NRC to maintain a surety with the State as the beneficiary, it is the responsibility of the licensee to provide NRC with verification of same; l ensure that the agreement with the State specifically identifies the financial i surety's application, uranium mill tailings site. and decommissioning / reclamation requirements; and transfer the long-term surveillance and control fee to the U.S. Department of the Treasury before l license termination.
All costs (unit and total) are to be estimated on the basis of independent contractor costs (include overhead and profit in unit costs or as 3 percent of total). Equipment owned by the licensee and the availability oflicensee staff should not be considered in the estimate to reduce cost calculations. All l costs should be based on current-year dollars. Credit for salvage value is generally not acceptable on the estimated costs.
De staff review may include a comparison of unit cost estimates with standard construction cost guides (e.g., Dodge Guide, Data Quest) and discussions with appropriate State or local autharities (highway cost construction). The licensee should provide supporting information or the basis for selection of the unit cost figures used in estimates.
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APPENDIX D GUIDANCE TO THE NRC STAFF FOR REVIEWING LONG-TERM SURVEILLENCE PLANS i
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1 APPENDIX D GUIDANCE TO THE NRC STAFF FOR REVIEWING '
LONG-TERM SURVEILLANCE PLANS l
1.0 BACKGROUND
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The Atomic Energy Act of 1954, as amended (hereafter, the Act) provides the statutory requirements for transfer of the title and custody to byproduct material and any land used for the disposal of such byproduct material from a uranium mill licensee to either Federal or State control, before termination of the licensee's specific license. These requirements are codified in 10 CFR Part 40, at paragraph i 40.28,
" General license for custody and long-term care of uranium or thorium byproduct materials disposal ,
sites." Section 40.28, along with pertinent requirements laid out in Appendix A to Part 40 (hereafter i Appendix A), provide for the completion of certain licensing actions before the transfer of the land and !
byproduct material to the United States or the appropriate State for long-term care. As part of the license ,
termination process, the intended custodial agency Federal or State government, will prepare a Long- l Term Surveillance Plan (LTSP) for review and concurrence / acceptance by the Nuclear Regulatory Commission. The LTSP is to document the General Licensee's plan for long-term care, including j inspection, monitoring, maintenance, and emergency measures necessary to protect public health and safety. This docuraent provides guidance to the NRC staff on review of the LTSP. SRP Appendix E provides guidance on the license termination process, and presents the role of the LTSP in the overall context of the license termination process.
l 2.0 REVIEW OF LTSP 2.1 Areas of Review l
1 As per 10 CFR 40.28(b), the LTSP should present the following information:
- A legal description of the disposal site to be transferred and licensed; l
- A detailed description of the final conditions of the disposal site, including existing ground-water l
I characterization;
- A description of the long-term surveillance program, including proposed inspection frequency and reporting to the Commission; frequency and extent of ground-water monitoring, if required; appropriate constituent limits for ground-water; inspection personnel qualifications; inspection procedures; record keeping; and quality assurance procedures;
- The criteria for followup inspections in response to unusual observations from routine inspections or extreme natural events; and
- The criteria for instituting maintenance or emergency measures.
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2.2 Information Reviewed 2.2.1 Legal Description and Ownership of the Land The reviewer shall examine the documents to ensure that the ownership and legal description of the land are satisfactory. The land ownership review shall include review of: (1) legal description of the disposal l site;(2) brief narrative of the disposal area land ownership, including the number of acres involved and I
the type of real estate instruments associated with the acquisitions; (3) information associated with the land transaction (i.e., book, page, county, State, and date of deeds; Federal Register number and date for transfer ofjurisdiction; and agreement number and date associated with DOF1 Tribe Agreement (waiver ofliability from tribe, ifland is owned by native Americans)); and (4) statement that real estate correspondence and instruments are maintained and filed by the Property Management Branch of the pertinent custodial agency. The documentation should clearly establish the custodial agency's land ownership when the land transfer takes place.
2.2.2 Final Condition of the Disposal Site The reviewer shall examine the following: (1) documentation of defined and charac'erized final closure site condition; (2) as-built drawings; (3) description of disposal cell design; (4) final topographic map; (5) vicinity map; (6) ground and areal photographs; (6) survey monuments, site markers, and signs; and (7) existing ground-water characterization and protection activities (if necessary), ground-water monitoring well network, screening monitoring to detect changes in ground-water quality from tailings (including evaluating the monitoring data to quantify the rate and magnitude of change). Some of the information may be referenced to the information already submitted to NRC (such as the completion report), and the staff findings on the previously submitted information may be used in this review. It is noted that the final disposition of the tailings residual radioactive material, or wastes at the milling site, should be such that ongoing active maintenance is not necessary to preserve isolation. The description of the final disposal site condition and the suggested ground-water monitoring should be of sufficient detail so that future inspectors have a baseline to determine changes to the site.
2.2.3 Long-Term Stu veillance Program The staff shall review the surveillance (inspection and monitoring) program for:
(1) Frequency ofInspection - The physical condition of the site (fence, site markers, drains / ditches, rock-mulch / vegetative cover etc.) should be inspected annually to determine any need for maintenance and/or monitoring. In addition, an inspection should follow an unusual event, such as heavy storm, or an earthquake. On the basis of a site-specific evaluation, NRC may require more frequent site inspections, because of the particular features of a disposal site.
(2) Reporting to the Commission - Results nf the inspections for all the sites under the licensee's jurisdiction will be reported to NRC annually within 90 days of the last site inspection in that calendar year. Any site at which unusual damage or disruption is discovered during the inspection, however, requires a preliminary site inspection report to be submitted within 60 days.
NUREG-1620 D-2
(3) Ground-water Monitoring - The reviewer shall examine long-term surveillance plans to ensure '
that a ground-water monitoring program is in place to verify that the ground-water quality at the site will continue to meet applicable standards. The long term surveillance plan will be acceptable if:
(a) Background, POC, and, if applicable, POE have been located as described in the existing license. Wells should be correctly located as to surface locations and aquifer completions. Well locations should be surveyed in and should be located on site ' cale maps. J (b) The same ground-water protection standards (point of ground-water protection j standards or ACLs) as the existing license continue to apply. If there has been j no leakage from the impoundment into the ground water, appropriate ground-water parameters should be monitored and detection concentrations established that will provide early warning ofleakage. Appropriate parameters should be indicative of the tailings material and not significantly affected by retardation reactions. For acid tailings appropriate detection parameters might include total dissolved solids, chloride or sulfate.
(c) The sampling frequency is sufficient to protect the public and environment at the POE and sufficient to ensure that the ground-water downgradient of the POC will not be degraded to any great extent before contamination is detected. 'Ihis l
will require a knowledge of potential contaminant plume velocities. It is j anticipated that the calculation of potential contaminant plume velocities will be l based on advective calculations. However, more complex calculations that I include such processes as dispersion and retardation may be performed if site conditions warrant them. For sites with ACLs, the sampling frequency should be sufficient to detect a potential contaminant plume, well before ground water at the point of exposure is degraded It is anticipated for most sites that routine monitoring of once every three years will be acceptable unless site-specific conditions warrant an increased or decreased frequency of monitoring. If more frequent monitoring is required; the reviewer shall also need to identify the increase in the long-term care payment that must be made to support the more frequent monitoring. This increase will need to be included in the existing surety as well as the long-term care payment made at the time oflicense termination. ;
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(d) Water quality sampling and analysis procedures use appropriate ASTM or ]
equivalent standards.' Wells should be constructed to prevent surface-water j contamination and capped and secured to prevent tampering by the populace. ]
(e) Any potential needs for future well maintenance or replacement are identified.
If periodic well replacement is projected, an increase in the long-term care !
payment must be included.
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(f) Actions that the long . nn custodian would take should ground-water protection standards be exceeded are described.
If the staff review results in acceptance of the long-term surveillance plan, the staff may conclude that DOE will conduct a Long Term Surveillance Plan that will confirm that constituents of concern will remain below the relevant standards in Part 40, Appendix A, Criterion 5B(5) and (6). The staff may also i conclude that enough funds are available to cover the costs oflong-term surveillance and control as I required in Part 40, Appendix A, Criterion 10 and tht site inspections are planned as required in Part 40, Appendix A, Criterion 12. 1 (4) Inspection Personnel Qualifications - The inspection team should be qualified to inspect such site features as subsidence and cracking; erosion by surface water; erosion protection (rock mulch l cover or vegetative cover) degradation; integrity of site markers, fences, and settlement plates, and ground-water monitoring to verify the presence and concentration limits of hazardous :
constituents in the ground-water. For inspections that follow unusual events, the team should consist of technical personnel of appropriate disciplines. l (5) Inspection Procedures - The LTSP should present details of the inspection procedures, such as checklist ofitems to be inspected; measurement or observation to be made; procedure for documenting the inspection data (photo, video, areal photo as needed); and duration of inspection (1 to 2 days).
(6) Recordkeeping and Quality Assurance Procedures - Inspection data should be retained in a ,
format suitable for future retrieval on a long-term basis. The quality assurance aspect of the )
collection of site and ground-water data, interpretation of the collected data, report preparation, and long-term retention of data should be reviewed.
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2.2.4 Follow-up Inspections The criteria for followup inspections in response to unusual observations from routine i
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inspections or extreme natural events should be reviewed.
(1) If any unusual observation from the inspection warrants a detailed evaluation, then an ,
unscheduled inspection (followup inspection) should be conducted for a detailed evaluation I of the unusual observation encountered in the earlier inspection. The plan should discuss the level of physical distress to the site (settlement / crack magnitude, extent of subsidence, >
extent of degradation of erosion protection, etc.) and limits of the constituents not to be exceeded in the ground water that would warrant a further detailed evaluation of the problem to determine the need for a restoration activity.
(2) Occurrence of extreme natural events, such as storms and earthquakes warrant an j inspection to verify the physical condition / integrity of the disposal site. The plan should I present the magnitude of the natural events that would trigger this inspection. I 2.2.5 Criteria for Instituting Maintenance or Emergency Measures NUREG-1620 D-4
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(3) Ground-water Monitoring - The reviewer shall examine long-term surveillance plans to ensure that a ground-water monitoring program is in place to verify that the ground water quality at the site will continue to meet applicable standards. The long term surveillance plan will be acceptable if:
(a) Background, POC, and, if applicable, POE have been located as described in the existing license. Wells should be correctly located as to surface locations and aquifer completions. Well locations should be surveyed in and should be located on site scale maps.
(b) The same ground-water protection standards (point of ground-water protection standards or ACLs) as the existing license continue to apply. If there has been no leakage from the impoundment into the ground water, appropriate ground-water parameters should be monitored and detection concentrations i established that will provide early warning ofleakage. Appropriate parameters l
should be indicative of the tailings material and not significantly affected by retardation reactions. For acid tailings appropriate detection parameters might include total dissolved solids, chloride or sulfate.
(c) 'Ihe sampling frequency is sufficient to protect the public and environment at the POE and sufficient to ensure that the ground-water downgradient of the POC will not be degraded to any great extent before centamination is detected. This will require a knowledge of potential contaminant plume velocities. It is anticipated that the calculation of potential contaminant plume velocities will be based on advective calculations. However, more complex calculations that include such processes as dispersion and retardation may be performed if site conditions warrant them. For sites with ACLs, the sampling frequency should be sufficient to detect a potential contaminant plume, well before ground water at the point of exposure is degraded.
It is anticipated for most sites that routine monitoring of once every three years will be acceptable unless site-specific conditions warrant an increased or decreased frequency of monitoring. If more frequent monitoring is required; the reviewer shall also need to identify the increase in the long-term care payment that must be made to support the more frequent monitoring. This increase will need to be included in the existing surety as well as the long-term care payment made at the time of license termination.
(d) Water quality sampling and analysis procedures use appropriate ASTM or equivalent standards. Wells should be constructed to prevent surface-water contamination and capped and secured to prevent tarnpering by the populace.
(e) Any potential needs for future well maintenance or replacement are identified.
! If periodic well replacement is projected, an increase in the long-term care payment must be included.
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l (f) Actions that the long-term custodian would take should ground-water protection standards be exceeded are described.
If the staff review results in acceptance of the long-term surveillance plan, the staff may conclude that DOE will conduct a Long Term Surveillance Plan that will confirm that constituents of concem will remain below the relevant standards in Part 40, Appendix A, Criterion 5B(5) and (6). The staff may also conclude that enough funds are available to cover the costs of long-term surveillance and control as required in Part 40, Appendix A, Criterion 10 and tht site inspections are planned as required in Part 40, Appendix A, Criterion 12.
(4) Inspection Personnel Qualifications - The inspection team should be qualified to inspect such site features as subsidence and cracking; erosion by surface water; erosion protection (rock mulch cover or vegetative cover) degradation; integrity of site markers, fences, and settlement plates; and ground-water monitoring to verify the presence and concentration limits of hazardous constituents in the ground-water. For inspections that follow unusual events, the team should consist of technical personnel of appropriate disciplines.
(5) Inspection Procedures - The LTSP should present details of the inspection procedures, such as f checklist ofitems to be inspected; measurement or observation to be made; procedure for documenting the inspection data (photo, video, areal photo as needed); and duration of inspection (1 to 2 days).
(6) Recordkeeping and Quality Assurance Procedures - Inspection data should be retained in a format suitable for future retrieval on a long-term basis. The quality assurance aspect of the collection of site and ground-water data, interpretation of the collected data, report preparation, and long-term retention of data should be reviewed.
2.2.4 Follow-up Inspections The criteria for followup inspections in response to unusual observations from routine ,
inspections or extreme natural events should be reviewed.
(1) If any unusual observation from the inspection warrants a detailed evaluation, then an unscheduled inspection (followup inspection) should be conducted for a detailed evaluation of the unusual observation encountered in the earlier inspection. The plan shoald discuss the level of physical distress to the site (settlement / crack magnitude, extent of subsidence, extent of degradation of erosion protection, etc.) and limits of the constituents not to be exceeded in the ground water that would warrant a further detailed evaluation of the pr6:em to determine the need for a restoration activity.
(2) Occurrence of extreme natural events, such as storms and earthquakes warrant an inspection to verify the physical condition / integrity of the disposal site. The plan should present the magnitude of the natural events that would trigger this inspection.
2.2.5 Criteria for Instituting Maintenance or Emergency Measures NUREG-1620 D-4
The plan should also present the criteria or the event that will trigger the initiation of maintenance and other emergency measures to restore the integrity of the disposal site and to protect the health and safety of the public. Quantitative and, if not practical, qualitative criteria that would trigger these measures should be discussed in the LTSP.
3.0 CONCLUSION
S On the basis of review of the LTSP, the staff should be able to conclude that the LTSP is in compliance
- with
- (1) the content requirements in 10 CFR 40.28(b) for LTSPs; (2) the ownership of site and l byproduct material requirement in Criterion 11 of Appendix A; and (3) the surveillance plan requirement in Criterion 12 of Appendix A. If the LTSPis in compliance with these requirements, the staff can accept the LTSP.
4.0 REFERENCES
U.S. Nuclear Regulatory Commission,1980a, " Final Generic Envirounental Impact Statement on Uranium Milling," NUREG-0706,3 vols, September 1980.
U.S. Nuclear Regulatory Commision,1980b, "OELD Legal Opinion on Two Questions Relating to Operation of the Uranium Mill Tailings Radiation Control Act of 1978," Shapar, H.K., memorandum to Commissioner Ahearne, April 28,1980. '
U.S. Nuclear Regulatory Commission,1990, "Rulemaking Issue (Affirmation): Amendments to 10 CFR Part 40 for General Licenses for the Custody and Long-Term Care of Uranium and Thorium Mill
) Tailings Disposal Sites," SECY-90-282, August 10,1990.
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L l NUREG-1620 D5 l
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i APPENDIX E GUIDANCE TO THE NRC STAFF ON THE LICENSE TERMINATION PROCESS FOR CONVENTIONAL URANIUM MILL LICENSEES
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1.0 BACKGROUND
l l The Atomic Energy Act of 1954, es amended (the Act) provides the statutory requirements for the j transfer of the title and custody to byproduct material and any land used for the disposal of such I byproduct material from a uranium mill licensee to either Federal or State rc .rol, before termination of the licensee's specific license. These requirements are codified in 10 CFR i 3.t 40, at paragraph 6 40.28,
! " General license for custody and long-term care of uranium or thorium byproduct materials disposal sites." Section 40.28, along with pertinent requirements la.d out in Appendix A to 10 CFR P,ut 40 (hereafter Appendix A), provides for the completion of certain licensing actions before the transfer of the land and byproduct material to the United States or the appropriate State for long-term care.
l The purpose of this document is to provide the U.S. Nuclear Regulatory Commission staff with specific l
directions to be applied in the course of the license termination process for Uranium Mill Tailings Radiation Control Act of 1978 (UlW1'RCA) Title II sites. The license termination process, including the roles of the respective involved organizations, is discussed in general, and then, various relevant issues are addressed in greater detail. This is the initial version of this guidance docu nent, and as specific uranium mill licenses are terminated and title to the land and byproduct material is transferred to the appmpriate governmental agency, future revisions are likely to be necessary. These revisions will address not only issues yet to be identified, but also will provide any additional necessary clarification of issues discussed herein.
2.0 ROLES OF INVOLVED ORGANIZATIONS l 2.1 U.S. Nuclear Regulatory Commission In accordance with Section 83c of the Act for NRC licensees, and Section 274c for Agreement State ,
licensees, before termination of the specific licensr, NRC determines whether the licensee has met all l
applicable standards and requirements under that license. For NRC licensees, this will involve NRC l review of licensee submittals, relative to the completion of decommissioning, reclamation, and, if necessary, greund-water cleanup. For Agreement State licensees, the State will conduct these reviews in j accordance with its standards and regulations. Under 10 CFR 40.28, NRC must concur with the State on i the termination ofits specific licenses NRC's determination with respect to Section 274c of the Act will ;
be conducted by the Office of State Programs (OSP) in consultation with the Office of Nuclear Material l Safety and Safeguards. It is anticipated that this determination will rely on OSP's reviews of the Agreement State's program and on the State's documentation of its conclusions concerning the licensee's performance of remedial actions.
In addition, the staff reviews the site Long-Term Surveillance Plan (LTSP) submitted by the custodial agency, for both NRC and Agreement State sites. On NRC acceptance of the LTSP, NRC terminates the specific license (or concurs in the Agreement State's termination) and places the long-term care and surveillance of the site by the custodial agency under the general beense provided at 10 CFR 40.28.
i l A final NRC responsibility is the determination of the final amount oflong-term site surveillance l funding. Criterion 10 of Appendix A specifies a minimum charge of $250,000 (1978 dollars), revised to l reflect inflation, which may be escalated on a site-specific basis because of surveillance and long-term monitoring controls beyond those specified in Criterion 12 of Appendix A. Detailed discussion of the bases used in developing the minimum charge and any escalated costs is pre Med in Section 3.4.
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2.2 Uranium Mill Licensees Befer-license termination, licensees are required by license conditions to complet- site decontamination and decommissioning, and surface and ground-water remedial actions consistent with NRC-approved (in the case of an NRC licensee) or Agreement State-approved (for an Agreement State licensee) decommissioning, reclamation, and ground-water corrective action plans.
Licensees will need to document the completion of these remedial actions in accordance with procedures developed by NRC or the Agreement State. As discussed in Section 3.1, for NRC licensees, this information will include a report documenting completion of tailings disposal cell construction and accompanying quality assurance / quality control (QA/QC) records, as well as radiation surveys and other information required under 10 CFR 40.42. Agreement State licensees will document their remedial action yrformance in accordance with the respective State requirements.
Because the LTSP must reflect the remediated condition of the site, the licensee will interact with the custodial agency in the preparation of the LTSP. Most likely, this will imolve supplying the custodial agency with appropriate documentation (e.g., as-built drawings) of the remedial actions taken and reaching agreements (formal or informal) with the custodial agency regarding the necessary surveillance control features of the site (e.g., boundary inarkers, fencing). It is the custodial agency's responsibility to submit the LTSP to NRC for appmval. However, the licensee may elect to help prepare the LTSP, to whatever degree is agreed to between the licensee and the custodial agency.
Finally, the licensee provides the funding to cover long-term surveillance of the site, in accordance with Criterion 10 of Appendix A. The final amount of this charge will be determined by NRC, based on the l final conditions of the site.
I After termination of the existing license and transfer of the site and byproduct materials to the custodial agency, a licensee's remaining liability extends solely to any fraudulent or negligent acts committed before the transfer to the custodial agency, as provided in Section 83b(6) of the Act.
l l 2.3 Custodial Agency Section 83 of the Act provides, that before termination of the specific license, title to the site and byproduct materials shall be transferred to either: (1) the U.S. Departmeat of Energy (DOE); (2) a Federal agency designated by the President; or (3) the State in which the site is located, at the option of the State. It is expected that DOE will be the custodial agency for most, if not all, the sites.
It is the responsibility of the custodial agency to submit the LTSP to NRC for review and acceptance. 1 Provisions and activities identified in the final LTSP will form the bases of the custodial agency's long-term surveillance at the site. NRC's acceptance of the LTSP will render that site licensed under the general license in 10 CFR 40.28. Custodial agencies att required, under 10 CFR 40.28(c)(1) and (c)(2),
to implement the provisions of the LTSP. These activities could include those not to be reflected in the long-term care charge, but voluntarily committed to by the custodial agency.
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NUREG-1620 E-2 1
- 1 2.4 States As discussed in Section 2.3, the State has the option of becoming the custodial agency for a site located within its boundaries. This *right of first refusal" may be exercised either on a site-by-site basis or so as to cover all sites within the State's limits. This option should be exercised early enough in the license terminttion process so thu termination of the specific license and transfer of the site to the appropriate custodial agency are not delayed unnecessarily. Written confirmation of a State's decision should be documented in a letter to DOE, from the Goverr.or of the State, or another State offic j to whom the authority for this decision has been appropriately delegated. A copy of this letter should be transmitted to NRC.
A State's authority over the regulation of the non-radiological constituents of ground-water is not impacted by its status, aor lack thereof, as a custodial agency for any site within its boundaries. A State's authority, however, does not extend to the radiological constituents of ground-water (NRC,1980b).
Finally, in addition to its potential role as a custodial agency, an Agreement State conducts the reviews of recl. aation and decommissioning plans and ground-water corrective action programs for its licensees.
Criteria used in these reviews are those applicable from Agreement State regulations that are compatible with the relevant requirements of Appendix A. Additionally, with NRC concurrence, an Agreement State terminates the specific licenses for its licensees, based on a review of a licensee's performance of rEn.edial actions, in accordance with approved plans.
3.0 THE LICENSE TERMINATION PROCESS A licensee considering termination ofits Source Material License should have in place an acceptable (by ,
NRC or Agreement State, whichever is appropriate) site decommissioning and reclamation plan and if !
necessary, an acceptable ground-wate corrective action program (CAP). This section describes the termination process that follows an NRC licensee's completion of decommissioning, reclamation, and ground-water corrective action in accordance with the approved plans. Specific procedures for NRC's l concurrence in the termination of Agreement State licenses are under development by OSP.
3.1 LICENSEE DOCUMENTATION OF COMPLETED REMEDIAL AND DECOMMISSIONING ACTIONS 3.1.1 Documentation of Completed Surface Remedial Actions Although uranium mill licensees are required to complete reclamation in accordance with an NRC- or Agreement State-approved plan, presently, there is no statutory or regulatory requirement for a licensee to submit formal documentation that the tailings disposal cell was reclaimed in accordance with the approved plan. However, for the staff to determine that all applicable standards and requirements have been met (under Section 83c of the Act), some form of documentation is necessary.
To ensure a timely and efficient NRC review, when reclamation of the tailings Jisposal cell is completed, the licensee should submit to NRC, for review, a repon detailing the conduct and completion of the reclamation constmetion activities. This Constmetion Completion Repon (CCR) would consist primarily of QA/QC records and as-built drawings. A licensee may refer to the repons prepared by DOE E-3 NUREG-1620
i to document completion of remedial actions at UMTRCA Title 1 Project sites as guidance in developing its CCR. However, some of the information provided in DOE's reports (e.g., original design calculations) is provided to ease the staff's review rather than to meet documentation requirements, if a CCR or similar report is not submitted, it vrill be necessary for the staff to conduct a detailed technical review, to meet its responsibilities under Section 83c of the Act. This review could involve several site visits and significant confirmation testing and would likely involve staff in the following technical disciplines: geotechnical engineering, surface water and erosion protection, and soil radiation cleanup. Accurate QA/QC records and photographs kept by a licensee during cell construction will be important input into the staff's determination that reclamation has been conducted and completed in accordance with the approved plan.
If the NRC determines, as part ofits review of the CCR or during a site inspection, that a licensee has neglected to compile QA/QC records or has inadequate records, NRC may require it to conduct appropriate sampling of those portions of the completed cell that are in question (e.g., of the radon barrier). If a licensee is unwilling or unable to comply, the staff or NRC contractors will conduct the sampling, and the costs invcived will be included in the licensing and inspection fees assessed under 10 CFR 170.31. In addition,if a requirement to maintain QA/QC records is part of an approved reclamation plan, a licensee's lack of such tecords may be interpreted as a violation of the relevant license condition.
Appropriate NRC action would be taken in such instances.
3.1.2 Documentation of Completed Site Decommissioning Licensees are also required, under 10 CFR 40.42(i), to document the results of site decommissioning, which is accomplished by conducting a radiation survey of the premises where the licensed activities were carried out. The results of this survey, the contents of which are specified at 10 CFR 40.42(i)(2),
are submitted to NRC for review. A licensee has the option of demonstrating that the premises are suitable for release in a manner other than that specified at 10CFR 40.42. Additional documentation peninent to site decommissioning and soil cleanup may be required by specific license condition.
3.1.3 Documentation of Completed Ground-water Corrective Actions Criteria 5A-5D, along with Criterion 13, of Appendix A, incorporate the basic ground-water protection standards imposed by the U.S. Environmental Protection Agency (EPA) in 40 CFR Part 192, Subpares D and E (48 FR 45926; October 7,1983).' These standards apply during operations and before the end of closure. At a licensed site, if these ground-water protection standards are exceeded, the licensee is required to put into operation a ground-water CAP (Criterion 5D of Appendix A). The objective of the CAP is to retum the hazardous constituent concentration levels to the concentration limits set as standards.
For licensees with continuing ground-water cleanup, NRC approval is required for the termination of corrective action. A licensee should submit appropriate ground-water monitoring data and other information that provide reasonable assurance that the ground-water has been cleaned to meet the approyi.4e standards. This may include an application for altemate concentration limits (ACLs) if the licensee concludes some ACLs for certain constituents are necessary. ACLs will be reviewed by the staffin accordance with the most current version of the NRC Staff Technical Position, " Alternate NUkEG-1620 E-4 4 l
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t i Concentration Limits for Title II Uranium Mills: Standard Format and Content Guide, and Standard Review Plan for Altemate Concentration Limit Applications"(Nuclear Regulatory Commission,1996).
3.2 NRC REVIEW OF COMPLETED CLOSURE ACTIONS On receipt of the CCR, decommissioning report, ground-water completion report, or ACL application, the staff will review the document fist for completeness and level of detail. Given a favorable finding, l the staff will then review the content of the report for documentation of acceptable completion of the l applicable aspect of closure. When, based on this review, the staff determines that the action has been conducted in accordance with the license requirements and regulations, NRC will notify the licensee by formal correspondence, and, if the licensee so requests, amend the specific license, by deleting applicable license requirements for reclamation, decommissioning, or ground-water cleanup, and identifying requirements for any disposal cell observational period and/or environmental monitoring. As pan of its review, staff will conduct site inspections, examining first-hand the closure actions taken, including the QA/QC records.
Additionally, staff will conduct a final construction-completion inspection, which is expected to consist of a site walk-over and an examination of construction records. No independent verification of completed actions (e.g., confirmatory coring of the radon barrier) is expected, except on a case-by-case basis, as discussed previously.
With respect to construction of the tailings cell, the staff's review of the CCR, coupled with site inspections, will ensure that the disposal cell was ccxtructed in accordance with the approved design and done so ** correctly" (e.g., QA/QC records show & appropriate number of material lifts were placed).
The staff will rely on site inspections as the primary means of determining acceptable implementation of the licensee's approved decommissioning plan, especially in % 4ds to soil cleanup. These inspections will consist of: (1) reviews of procedures, (2) evaluations of procedure implementation, (3) evaluations of records and quality assurance, and (4) limited gamma surveys and soil sanspling. In this way, the staff will gain a needed level of confidence in the licensee's performance to support its evaluation of the final decommissioning survey report. Confirmatory sampling, either by NRC or its contractors, will be conducted at sites for which additional confirmation beyond inspections is necessary. Specific criteria will be employed to identify those sites requiring confirmatory sampling.
3.3 OBSERVATIONAL PERIODS 3.3.1 Following Completion of Surface Remedial Actions Although no statutory or regulatory requirement exists for an observational period following the completion of surface remedial actions, this period is necessary for NRC to assess the potential long-I term stability of the tailings disposal cell. The length of this observational period will be determ:ned on a site-specific basis, with a minimum period of one year, commencing at the completion of the erosion cover. Licensees should report significant cell degradation (e.g., the development of settlement or crosional features) occurring during this period.
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Sites employing a "... full self-sustaining vegetative cover" (Criterion 4 of Appendix A) will be required to have an observational period of at least two years, and possibly as long as five years, consistent with the bases for Appendix A (Nuclear Regulatory Commission,1980). {
A defacto observational period may exist at most sites where cleanup of ground-water contamination j continues following the completion of surface reclamation (i.e., construction of the tailings disposal cell).
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I 3.3.2 Ground-water Remediation The reviewer shall examine (1) ground-water completion reports, (2) ground-water corrective action reports, or (3) ACL applications to verify that the 1 year stability ground-water monitoring period confirms that ground-water quality corrective actions have produced a stable water quality and that 4 ground-water monitoring and analysis have been done to confirm the concentration of these contaminants in the ground water and to verify that they meet applicable standards.
1 Ground-water stability monitoring and confinnation of constituents of concern will be acceptable if: )
(1) A one-time measurement of all constituents of concern has been collected and analyzed from all point of compliance wells. A constituent of concern is one that is (1) cither (a) currently identified in Part 40, Appendix A, Criterion 13, or (b) is not listed in Criterion 13, but is placed in a license condition as part of the staff's review of the Corrective Action Plan; and (2) has been identified in the tailings liquor. NRC has flexibility to add other constituents not identified in Criterion 13. However, in identifying this second set cf constituents, the staff should ensure that any additions are made based on a sound technical and regulatory basis. Before requiring additional constituents it should be considered if such constituents are covered by ongoing State ground-water programs. New constituents should be added in a timely manner. This is either at the time the Corrective Action Plan is accepted for review, or at sometime during the lifetime of the Corrective Action Plan. New constituents will not be required at the time of the license-termination monitoring submittal.
Exauples of sound technical bases include the following:
(a) NRC r.nd the EPA agree to use one Federal contact with a licensee, which is NRC. This approach requires NRC to include some constituents, in its licenses, that are not normally licensed by the NRC.
(b) Trends in ground-water contamination show that after several years of decreases in the level of contamination, the level of contamination is beginning to rise again.
, (c) Surrogate parameters that cover a family of constituents show an increase in the l concentration in ground water. Therefore, the staff may require licensees to monitor for all constituents found in that family.
(d) Some constituents used in the milling process, but not listed in Criteria 13, such as ammonia and nitrate need to be covered.
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Constituents should not be added just because an individual State regulatory body is concemed about that constituent. In identifying constituents of i segulatory concem not covered in Criterion 13, the reviewer must ensure that an individual State does not use the NRC to implement the ground-water programs
- l. that are the responsibility of the State. Having a State identify a constituent as l one of concern to the State is not necessarily a proper basis for NRC to include that constituent.
(2) ihe results of the one-time measurement sampling should be compared with the pre-mining applicable standards r, e rified in Criterion 5(c) or the license. All hazardous constituents must be shown to meet the standards specified in 5(c) or the license. If this measurement is taken sometime before license termination (three or more years), the reviewer will need to ensure that recontamination has not occurred. *Ihis may be accomplished by additional l measurements or analytical calculations.
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! (3) The stability monitoring data should be inspected for any trends in increasing ground-water concentrations for those constituents of concern in the ground water that were being cleaned up by the Corrective Action Plan.
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- If the staff review results in acceptance of confirmation and stability monitoring, the staff may conclude l that
! (1) 'Ihe licensee has monitored all previously identified constituents of concern at the points of j compliance.
l (2) The post-Corrective Action Plan stability monitoring shows that the constituents of concem that j were remediated will remain below compliance or ACL standards. '
( (3) The one-time sampling for cor.stituents of concere shows that constituents of concem are below and will r: main below relevant standards in Part 40, Appendix A, Criterion 5B (5) and (6)
(4) All ground-water Corrective Action Plans have ceased operation. !
! (5) All identified constituents of concem for which compliance sampling is being conducted have l been returned to the concentration limits set as standards.
! 3,4 LONG-TERM SITE SURVEILLANCE FUNDING I Before termination of the specific license, NRC will set the final amount of the long-term site !
i surveillance charge to be paid by the licensee in accordance with Criterion 10 of Appendix A. NRC's process for determining this amount will include consultations with the licensee and the custodial agency. Payment of this charge to the U.S. general treasury or to the appropriate State agency is required before termination of the specific license.
3.4.1 Bases for Determination of Surveillance Charge i
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The basic criterion for tailings disposal is to not depend on perpetual human care and maintenance to preserve the isolation of the tailings. NRC,in Criterion 1 of Appendix A, concludes that:
"The general goal or broad objective in siting and design decisions is permanent isolation of tailings and associated contaminants by minimizing disturbance and ,
dispersion by natural forces, and to do so without ongoing maintenance."
However, as further indicated in Criterion 1, for practical purposes, specific design and siting considerations must involve finite time limits. For this reason, Criterion 6 contains longevity standards for design of the disposal cell.
So the isolation of the tailings and as:ociated contaminants can be preserved to the extent possible, the Act provided that title to the byproduct material and associated land be transferred to the care of the United States or the State, as discussed previously. NRC has interpreted such long-term custody by a governmental agency, whether Federal or State, as "...a prudent, added measure of control" (NRC, 1980a), so that land uses that might contribute to the degradation of the cover or lead to direct human exposures can be prevented.
In the final Generic Environmental Impact Statement (GEIS) on Uranium Milling (Nuclear Regulatory Commission,1980a), NRC staff developed the bases for the long-term surveillance charge, given the
, intent that no ongoing active maintenance of site conditions should be necessary to preserve waste l isolation. In the GEIS, the assumptions underlying the so-callal " passive monitoring" approach to l surveillance of the site are as follow:
l (1) An annual visual inspection of the site, either as a site visit or in a flyover, lasting one to two l days; l (2) No maintenance of equipment or facilities, no fence replacement, and no sampling nor airborne
( environmental monitoring would be expected.
(3) Essentially, the only costs for continued surveillance / maintenance would consist of time spent in i l preparing for the inspection, travel to the site, conduct of the inspection, and annual report writing; and
- (4) Minimal NRC oversight would be required.
<a <e monitoring, thus, would not involve such activities as: irrigation, hauling of fill, regrading, or seeding.
I Finally, as discussed previously, licensees will contribute the funds necessary to cover the costs of long- {
term surveillance of their sites. The charge assessed is a one-time fee, and of an amount such that J interest on the funds, assuming a 1 percent annual real interest rate, will yield a corresponding amount ;
sufficient to cover the annual costs of site surveillance. The GEIS provides more detailed discussion j regarding the determination of this interest rate.
3.4.2 Determination of Surveillance Charge Amount NUREG-1620 E-8
r Based on the assumptions discussed in Section 3.4.1, NRC developed the minimum long-term surveillance charge of $250,000 (1978 dollars) reflected in Criterion 10 of Appendix A. It is this charge, adjusted to account for inflation, that the licensee is required to pay into the general treasury of the United States, or alternately, to the appropriate State agency (if the State is to become the long-term site custodian). The methodology the staff will use to determine the adjusted surveillance charge that accounts for inflationary increases since 1978 involves: (1) using the Consumer Price Index (CPI) available at the time the licensee requests termination and (2) applying the rate of increase for the last month for which it has been calculated to any following month leading to license termination. For example, in June 1996, NRC determined the final surveillance charge for the TVA/Edgemont site. In doing so, the staff used the April 1996 CPI and applied the rate of increase between March and April to the months of May and June.
Criterion 10 does allow for the escalation of this minimum charge, if, on the basis of a site-specific evaluation, the expected site surveillance or control requirements are determined to be significantly greater than those specified in Criterion 12 of Appendix A (i.e., annual inspections to confirm site integrity and determine the need, if any, for maintenance and/or monitoring).
Escalation could result from a licensee's propon1 of attematives to the requirements in Appendix A, as allowed under Section 84c of the Act. For example, a licensee could demonstrate by analysis that the only mechanism for achieving a minimum disposal cell design life of 200 years at its site is though the use of ongoing maintenance. NRC may approve such a design if it finds that the design will achieve a level of stabilization and containment for the site concemed, and a level of protection of public health and safety, and of the environment, that is equivalent to, to the extent practicable, or more stringent than, the level which would be achieved by NRC's requirements. However, the licensee would likely be required to place additional funds in the long-term surveillance charge to cover the costs of the ongoing maintenance.
Another situation that may lead to the escalation of the minimum charge is the recognition that sonae degree of active care (e.g., fence upkeep, vegetation control, maintenance of crosional control measures) is necessary to preserve the as-designed conditions of the site. This need should become apparent in the course of site observations during the reclamation and observational periods.
In any case, any escalation in the minimum charge will be discussed with the licensee and long-term custodian, before license termination. Any final variance in the funding requirements will be determined solely by NRC.
A situation may arise in which the custodial agency desires to have commitments in the LTSP that are beyond those required in Appendix A and which are not determined necessary by NRC. In such a case, the amount of the long-term surveillance charge would not be affected (NRC,1990;" Detailed Comment Analysis," Comment 1.2). The custodial agency will need to identify a mechanism for funding these additional self-imposed requirements.
3.4.3 Payment of Long-Term Surveillance Charge Licensees may pay the final site surveillance charge directly to the NRC or the custodial agency. If paid to NRC, the funds will be deposited, in accordance with the Miscellaneous Receipts Act,in the U.S.
General Treasury. A custodial agency receiving payment from the licensee, will need to document E-9 NUREG-1620 I
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l receipt and subsequent deposition of the payment. Copies of such documentation should be provided to l NRC.
Finally,10 CFR 150.32(a) provides that, when an Agreement State license is terminated and the disposal site is to be transferred to the Federal government for long-term care, all funds collected by the
- Agreement State for the purposes of long-term surveillance will be transferred to the United States.
l 3.5 PREPARATION OF THE LONG-TERM SURVEILLANCE PLAN l
While surface remediation and ground-water cleanup activities are ongoing, it is in the best interest of the licensee to begin interaction with the custodial agency with regard to that agency's preparation of the site LTSP. The custodial agency's responsibilities under the general license are defined in the LTSP, the
- required contents of which are provided at 10 CFR 40.28 and in Criterion 12 of Appendix A. These contents include
- A legal description of the site to be transferred and licensed;
- A detailed description of the site, as a baseline from which future inspectors can determine the nature and seriousness of any changes (licensees may reference previously submitted information, to the extent applicable, in providing this description (10 CFR 40.31(a)));
- A detailed description of the long-term surveillance prograne including: (a) the frequency of inspections and reporting to the NRC; (b) the frequency and extent of ground-water raonitoring, if required; (c) appropriate ground-water concentration limits; and (d) inspection procedures and personnel qualifications;
- The criteria for follow-up inspections in response to observations from routine inspections or extreme natural events; and ,
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- The criteria for instituting maintenance or emergency measures. l l
In addition to these regulatory requirements, NRC will also require that the LTSP contain documentation l of title transfer of the site from the licensee to the custodial agency. This requirement does not apply to sites located on Indian lands, since transfer does not occur for such sites (Criterion ilF of Appendix A).
Because the LTSP must reflect the remediated condition of the site, it is expected that the existing licensee willinteract with the custodial agency in the preparation of the LTSP. As discussed in Section 2.2, this will likely involve supplying the custodial agency with appropriate documentation (e.g., as-built drawings) of the remedial actions taken and reaching agreements (formal or informal) with the custodial agency regarding the necessary surveillance control features of the site (e.g., boundary markers, fencing).
Although it is possible that the LTSP may be prepared by the licensee, it is more likely that the documera will be developed by the custodial agency, since the LTSP will reflect post-transfer responsibilities committed to by the custodial agency. The LTSP must be submitted to NRC for approval by the custodial agency.
As the likely custodial agency for most, if not all, of the sites, DOE has proposed an approach intended to streamline NRC staff reviews of site LTSPs. This approach would involve NRC approval of a NUREG-1620 E-10
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seneric LTSP shell" prepared and submitted by DOE. For sites under the long-term care of DOE, significant portions of the LTSP will not change from site to site (e.g., criteria for followup inspections and for instituting maintenance or emergency measures). NRC's approval of the "shell" would cover this generic information, and allow NRC staff to focus its review on the site-specific information in the LTSP. This information may reflect site-specific activities that are not to be reflected in the long-term care charge, but are voluntarily committed to by the custodial agency.
3.6 SITE READY FOR LICENSE TERMINATION When a licensee has completed site reclamation, decommissioning, and, if necessary, ground-water corrective action, and is ready to terminate its specific Source Material License, it will need to formally notify NRC ofits intentions. Such notification should be accompanied by a completed NRC Form 314,
" Certificate of Disposition of Materials."
Additionally, an environmental report (ER) is requiad under 10 CFR 51.60(b)(3) for termination of a license for the possession and use of source material for uranium milling. However, because the environmental impacts associated with reclamation and deconunissioning of a uranium mill site will already have been assessed by NRC staff before license termination, licensees seeking license termination can submit a supplemental ER summarizing site decommissioning and reclamation objectives, activities, and results.
i Agreement State licensees should apply to their Agreement State for license termination, providing the l appropriate State-required documentation as needed.
3.7 TERMINATION OF THE SPECIFIC LICENSE / ISSUANCE OF THE GENERAL LICENSE Actual termination of a licensee's specific license and the subsequent placement of the site under the general license provisions of 10 CFR 40.28 will involve a number of separate actions to be completed by NRC. Significant intemal coordination (and external, if Agreement State licensees are involved) will be required so that these actions will be completed in an efficient and timely manner, thereby ensuring that the byproduct material and any land used for the disposal of such byproduct material remain under NRC license throughout the process.
3.7.1 NRC Determination under Section 83c/274c of the Act Under Section 83c of the Act for NRC licensees, or Section 274c for Agreement State licensees, NRC determines whether all applicable standards and requirements have been met by the licensee in the completion of site reclamation, decommissioning, and ground-water corrective action. Necess.arily, this determination will rely primarily on NRC or Agreement State reviews and acceptance of the documentation provided by the licensee. In addition, NRC or Agreement State site closure inspection activities, potentially including limited confirmatory radiological surveys, will provide supplemental information to NRC's determination.
For Agreement State licensees, NRC's periodic reviews of the Agreement State's regulatory program will 1 provide confidence that the State's reviews and licensing actions associated with termination have been E-11 NUREG-1620
t conducted appropriately, from a technical, administrative, and procedural perspective. The staff will not conduct independent detailed technical reviews of a Agreement State licensee's documentation of completed site decommissioning and reclamation. j l
3.7.2 NRC Review and Acceptance of the LTSP 1 i
An LTSP is required before termination of the specific heense and placement of the site and byproduct material under the 10 CFR 40.28 general license. Review and acceptance of the LTSP is the sole :
purview of NRC. Formal concurrence on the LTSP by other entities, including the State in which the site
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is located, is not provided for, since these entities have no regulatory authority under the Act, during the long-term care period. However, NRC will accept public comments on any licensing action taken by the Commission. Lack of NRC acceptance of a site LTSP can delay termination of the specific license. !
i NRC staff's acceptance of an LTSP will be documented in written notification to the custodial agency, I and, separately, by noticing the action in the Federal Recister. In addition, for Agreement State l licensees, NRC will also notify the relevant Agreement State of the action. j i
3.7.2.1 Issuance of a specific order under 10 CFR40.28 )
If an acceptable IJTSP has not been received by NRC for a reclaimed site ready for transfer to the custodial agency, two options are available to NRC. First,if appropriate, the Commission may choose to not terminate the existing license for a shon period of time, while awaiting an acceptable LTSP.
Alternately, under 10 CFR 40.28, NRC may issue a specific order to the custodial a3ency to take custody of the site and to commence long-term surveillance, while the agency prepares the LTSP for final NRC approval.
A substantial supponing basis would be required to support NRC issuance of an order. An (
understanding of the circumstances leading to the custodial agency's inability to take the site would also i be necessary. Factors that would be considered include whether:
i (1) Adequate notice (at least 16 months) has been provided by the existing licensee to allow the custodial agency to effect title transfer to the land and byproduct material; (2) Sufficient time (at least two years) has been allowed for the custodial agency to prepare, and the NRC to review, the LTSP; (3) NRC has reviewed the CCR, decommissioning report, and ground-water cleanup repcrt, i j
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and conducted the final license-termination inspection and found that the closure actions were completed in an acceptable manner; (4) Site degradation has occurred, and if so, whether appropriate re' pairs have been completed; (5) The required long-term surveillance funding payments have been made to the U.S. General ;
Treasury or to the designated State agency; and i (6) The custodial agency has an acceptable basis for delaying for inclusion of the site under the l
generallicense.
NUREG-1620 E-12 1
In cases where DOE or another Presidentially designated Federal agency is to be the long-term custodian, and is unable to take custody of the site because of lack of funding, NRC may still order the agency to do so. The intended custodial agency will have at most one year (i.e., the time by which an annual site inspection is to have been completed) in which to obtain the funds through the necessary appropriations process.
3.7.3 Transfer of Site Control to the Custodial Agency Given a determination that all applicable standards and requirements have been met and acceptance of the site LTSP, NRC will need to complete the remaining relevant licensing actions: (1) terminating the specific license by letter of terrnination addressed to the specific licensee, or concurring in the Agreement State's termination of the specific license; (2) placing the site under the general license in 10 CFR 40.28; (3) noticing, in the Federal Recister. the completion of these licensing actions; and (4) informing appropriate Federal and State officials directly of the termination of the specific license and the placement of the site under the general license.
For Agreement State licenses, these actions will need to be closely coordinated with the relevant Agreement State. After NRC's concurrence in the proposed action, the Agreement State should be ready to terminate the specific license, and to transfer the long-term care fonds to the U.S. General Treasury, on notification from NRC that the LTSP has been accepted. The long-term custodian, for its part, should be prepared to accept title to the land and byproduct material. Completion of these final actions should .
occur within a relatively short period of time (e.g., within a week).
4.0 ADDITIONAL ISSUES 4.1 UMTRCA TITLE II SITES ON INDIAN LANDS For UMTRCA Title II disposal sites on Indian lands, UMTRCA provides that long-term surveillance will be accomplished by the Federal govemmcat and that the licensee (i.e., the custodial agency) will be required to enter into arrangements with NRC to ensure this surveillance. UMTRCA does not state explicitly which Federal agency is responsible for the disposal site. In addition, because these sites are located on Indian lands, no title transfer will occur.
NRC will work out long-term care arrangement for these disposal sites on a case-by-case basis. Likely, this will involve a site access agreement between the Indian Tribe, the custodial agency, and NRC, to allow the custodial agency to conduct the required site surveillance. Currently, the only site on Indian lands is Westem Nuclear, Inc.'s Sherwood uranium mill, located on the Spokane Indian Tribe reservation in eastern Washington State.
! 4.2 CONCURRENT JURISDICTION It is the intent of NRC staff to make a good-faith effort in working with the States on issues related to a licensee's completion of remedial actions and preparation for license termination. However, concurrent jurisdictional issues between NRC and the States may arise over the rerulation of the non-radiological j constituents of ground-water (previously, NRC has concluded that it has sole jurisdiction over the
( radiological ground-water constituents (NRC,1980b)). Such issues would involve disagreements over
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f the ground-water concentration limits to which licensees must restore, especially when a State's l concentration limits for certain constituents are lower than NRC's. Although NRC will, to the extent i possible, accommodate a State's perspective, it retains the right to terminate a specific license should a licensee have completed closure activities in accordance with NRC-approved closure plans.
Where the issues involved are not those of direct NRC concern, NRC will address such issues with the
- States or other Federal agencies on a case-by-case basis.
1 Currently, four sites (two NRC licensees -- the United Nuclear Corporation / Church Rock site; and the Homestake Mining Company / Grants site - and two Agreement State licensees -- the Cotter Corp / Canon l City and the UMETCO/Uravan sites, both in Colorado) are on the Superfund National Priorities List.
For these sites, NRC considers that it will need to determine ifit is appropriate to terminate any of these licenses on a case-by-case basis.
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5.0 REFERENCES
Nuclear Regulatory Commission,198C " Final Generic EnvironmentalImpact Statement on Uranium Milling " NUREG-0706,3 vols, September 1980.
l Nuclear Regulatory Commission,1980b. "OELD Legal Opinion on Two Questions Relating to Operation of the Uranium Mill Tailings Radiation Control Act of 1978," Shapar, H.K., memorandum to Commissioner Ahearne, April 28,1980.
i Nuclear Regulatory Commission,1990. "Rulemaking Issue (Affirmation): Amendments to 10 CFR Part 40 for General Licenses for the Custody and Long-Term Care of Uranium and Thorium Mill Tailings Disposal Sites," SECY-90-282, August 10,1990.
1 Nuclear Regulatory Commission,1996. " Staff Technical Position: Alternate Concentration Limits for l Title II Uranium Mills: Standard Format and Content Guide, and Standard Review Plan for Altemate
' 1 Concentration Limit Applications," February 1996.
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APPENDIX F GUIDANCE TO THE NRC STAFF ON EFFLUENT DISPOSAL AT LICENSED URANIUM RECOVERY FACILITIES CONVENTIONAL MILLS
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APPENDIX F GUIDANCE TO THE NRC STAFF ON EFFLUENT DISPOSAL AT LICENSED URANIUM RECOVERY FACILITIES CONVENTIONAL MILLS BACKGROUND l
NRC-licensed uranium mill recovery facilities, generate liquid wastes (i.e., effluent) that require proper disposal. Nuclear Regulatory Commission Office of Nuclear Material Safety and Safeguards policy is presented below.
PURPOSE AND APPLICABILITY This appendix provides guidance and discusses the technical and regulatory basis for review and evaluation of applications for disposal ofliquid waste. It is primarily intended to guide NRC staff reviews of site-specific applications for disposal of liquid.
ONSITE EVAPORATION Applications for onsite evaporation systems must demonstrate that the proposed disposal facility is designed, operated, and closed in a manner that prevents migration of waste from the evaporation systems to a subsurface soil, groundwater, or surface water in accordance with 10 CFR Part 40, l Appendix A. Applicants must also demonstrate that site-specific groundwater protection standards and monitoring requirements are adequately established to detect any migration of contaminants to the groundwater and to implement corrective action to mstore groundwater quality if and when necessary as mquired by the regulations.
If surface impoundments are employed for evaporation, but they are not used for waste disposal, they must comply with the design provisions for surface impoundments [ criteria SA(1) through 5A(5)];
I installation ofliners (Criterion SE); and seepage control (Criterion 5F) of 10 CFR Part 40, Appendix A.
However, if surface impoundments are employed for evaporation and waste disposal, they must comply with the regulatory requirements in 10 CFR Part 40, Appendix A. These include the design provisions for surface impoundments [ criteria SA(1) through 5A(5)]; installation ofliners (Criterion SE); and seepage control (Criterion 5F). In r idition, evaporation ponds must also meet other generally applicable regulatory provisions in Appendix A, including in particular the site-specific groundwater protectiori standards and leak detection (criteria 5B and SC); corrective action programs (Criterien 5D);
groundwater monitoring requirements (Criterion 7); and closure requirements (Criterion 6).
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, i RELEASE IN SURFACE WATERS The new source performance standards [40 CFR 440.34(b)] stipulate that for new sources there shall be no discharge of process wastewater to navigable waters from mills using the acid lem , alkaline leach or combined acid and alkaline leach process for the extraction of uranium.
LAND APPLICATIONS Proposals for disposal of liquid waste by land applications, including irrigation, must demonstrate that doses are maintained As Low As Reasonably Achievable (ALARA) and within the dose limits in 10 CFR 20.1301. Proposed land application activities must be described in sufficient detail to satisfy the NRC need to assess environmental impacts. This may require analysis to assess the chemical toxicity of radioactive and nonradioactive constituents. Specifically, licensees must provide (1) a description of the waste, including its physical and chemical properties that are imponant to risk evaluation; (2) the proposed manner and conditions of waste disposal; (3) projected concentrations of radioactive contaminants in the soil; and (4) projected impacts on groundwater and surface water quality, and on land uses including particularly crops and vegetation. In addition, projected exposures and health risks l must be analyzed that may be associated with radioactive constituents reaching the food chain to ensure that doses are ALARA and within the dose limits in 10 CFR 20.1301. Proposals should include provisions for periodic soil surveys to verify that contammant levels in the soil do not exceed those ,
projected, and a remediation plan that can be implemented in the event that the projected levels are !
exceeded. Appropriate state and federal agency permits must be obtained per 10 CFR 20.2007 and the applicant will be required to comply with NRC regulatory provisions for decommissioning.
DEEP-WELL INJECTION Proposals for disposal of liquid waste by injection in deep wells musts must meet the regulatory provisions in 10 CFR 20.2002 and demonstrate that doses are ALARA and within the dose limits in 10 CFR 20.1301. The injection facility must be described in sufficient detail to satisfy the NRC need to assess environmental impacts. Specifically, proposals must include a description of the waste, including its physical and chemical properties important to risk evaluation; the proposed manner and conditions of waste disposal; an analysis and evaluation of pertinent information on the nature of the environment; information on the nature and location of other potentially affected facilities; and analyses and procedures to ensure that doses are ALARA, and within the dose limits in 10 CFR 20.1301.
1 In addition, pursuant to the provisions of 10 CFR 20.2007, pmposals for disposal by injection in deep wells must also meet any other applicable federal, state, and local. government regulations pertaining to deep well injection, and obtain any necessary permits for this purpose. In panicular. proposals rr st satisfy the EPA regulatory provisions in 40 CFR Part 146: Underground Injection Control Program:
Criteria and Standards, and obtain necessary permits from the EPA and/or States authorized by EPA to enforce these provisions. In general, applications that satisfy the EPA regulations under the Underground Injection Control Program and the applicable provisions of 10 CFR 20 will be approved by NRC staff.
Licensees and applicants disposing effluent by injection in deep wells are further required to comply with NRC's regulatory provisions for decommissioning. Abandonment of wells should be done in accordance with the requirements of the state engineer.
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! APPENDIX G l
i NATIONAL HISTORIC PRESERVATION ACT AND j ENDANGERED SPECIES ACT :
CONSULTATIONS i
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APPENDIX G NATIONAL PERSERVATION HISTORIC ACT AND ENDANGERED SPECIES ACT CONSULTATIONS I
1.0 BACKGROUND
Prior to completion of the licensing action, Section 106 of the National Historic Preservation Act (NHPA) requires federal agencies to take the effects of actions licensed by federal agencies on properties included in or eligible for the National Register of Historic Places. The implementing regulations for l Section 106 are found in 36 CFR Part 800. Similarly, Section 7 of the Endangered Species Act (ESA) requires that federal agencies consult with the U.S. Fish and Wildlife Service on any federal action that could impact endangered species or their habitats. 50 CFR Part 402, Subpart B contains the regulations related to such consultations. The purpose of this appendix is to provide guidance to the U.S. Nuclear Regulatorf Commission (NRC) staff on how to fulfill the NRC's obligations under the NHPA and the ESA.
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2.0 NATIONAL HISTORIC PRESERVATION ACT -
2.1 Review Procedures I The staff shall determine that the applicant has used the appropriate databases and records to identify 1 historic, archaeologic, scenic, cultural, or natural landmarks that are found within the study region. The staff shall determine that the locations and descriptions of the landmark features are acceptable to allow an evaluation of the likely consequences of any impacts of the proposed facihties. Of particular interest are landmarks included in the National Registry of Natural Landmarks and/or the National Register of Historic Places. Means to consider and treat such data are discussed in the SFCG (U.S. Nuclear Regulatory Commission,1982). The reviewer shall verify that data presented supports the determination of estimates of long-term costs of any licensed activity in terms of the likely consequences of any eftects on the aesthetic or recreational values of such landmarks. If an applicant indicates that there are no l landmarks within the sutdy region, it is important that the application document evidence of contact with I knowledgeable sources. The reviewer shall examine the likely impact of the presence of new roads, pipelines, or other utilities on areas and locations of known historic, scenic, cultural, natural, )
archaeologic, or architectural significance.
The reviewer shall also confer with the SHPO in accordance with the National Historic Preservation Act l (NHPA), Section 106, and NHPA Bulletin 38. As specified in 36 CFR Part 800, the SHPO can enter into i a memorandum of understanding (MOU) to assume the function of the Advisory Council on Historic l l Preservation (ACHP). In these situations, consistent with 36 CFR 800.7(b)(1), NRC can comply with the l l State review process in lieu of the ACHP regulations. If such an MOU is not in place, the staff must consult with the SHPO and other interested parties, as specified by 36 CFR Part 800 and follow the j
, requirements of 36 CFR 800.4 through 800.6. .
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For license renewals and amendment applications, Appendix A to this SRP provides guidance for examining facility operations and the approach that should be used in evaluating amendments and G-1 NUREG-1620 1
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'e renewal applications. {
2.2 Acceptance Criteria j The characterization of regional historic, archeological, scenic, cultural, md natural landmarks is acceptable if it meets the following criteria:
(1) A listing of all areas included in or eligible to be incluc ed in the National Registry of Historic Landmarks is provided.
(2) A listing for all properties included in or c'igible for inclusion in the National Register of Historic Places is provided. 4 (3) A map is included indicating where all identified historic landmarks and historic places J with respect to the location of facilities such as buildings, new roads, well fields, j pipelines, surface impoundments, and utilities that might affect these areas are located, j 1
The license shall contain a condition prohibiting work if cultural artifacts are found in locations other than those indicated on this map.
(4) Discussions of the treatment of areas of historic, archeological, architectural, scenic, and cultural significance that follow guidance equivalent to that provided by the National Park Service Preparation of Environmental Statements: Guidelines for Discussion of Cultural (Historic, Archeological, Architectural) Resources (National Park Service, 1973). Where appropriate, tribal authorities shall have been consulted for the likely consequences of any impact on Native American cultural resources. For a consideration of environmentaljustice, see Section 7.6.1.3, Acceptance Criterion (3) and Appendix B.
(5) Evidence is provided of contact with the appropriate SHPO and tribal authorities. This evidence includes a copy of the SHPO and tribal authority comments conceming the j effects of the proposed facility on historic, archeological, architectural, and cultural ;
resources. 1 I
(6) The applicant presents a Memorandum of Agreement accompanied by specified documentation between the SHPO, tribal authorities, and other interested parties regarding their satisfaction with regard to the protection of historic, archeological, architectural, and cultural resources during site constmetion and operations.
(7) A letter from the SHPO has been obtained that describes if there are any issues associated with the State or Federal register or any sites eligible for inclusion in the State or Federal register.
(8) A letter has been obtained from the SHPO describing archeological sites (cultural resources) that may be affected by the ISL operations.
(9) The aesthetic and scenic quality of the site is rated in accordance with the U.S. Bureau of Land Management (BLM) Visual Resource Inventory and Evaluation System (U.S.
Bureau of Land Management,1978).
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l.s e I If the rating is below 19 (scale of 0 to 33), no special management is required. If the l rating is 19 or atove, the application provides a management plan for minimizing the l impact of the proposed facility.
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2.3 Evaluation Findings
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! If the staff's review as described in this section results in the acceptance of the characterization of the ,
I regional historic, archeological, architectural, scenic, cultural, and natural landmarks, the following conclusions may be presented in the Environmental Assessment (EA).
NRC has completed its review of the site characterization information concerned with regional historic, l archeological, architectural, scenic, cultural, and natural landmarks near the mill l l site. This review included an evaluation using the review procedures in Appendix G, Section 2.1 of NUREG-1620 and the acceptance criteria outlined in Appendix G, Section 2.2 of NUREG-1620. I The licensee has acceptably described the regional historic, archeological, architectural, scenic, cultural, and natural landmarks. A listing of all nearby areas and propenies included or eligible for inclusion in the National Registry of Natural Landmarks or the National Register of Historic Places is provided. A map indicating where all historic landmarks and places with espect to facilities are located. A record of the investigation of places and propenies with historic, archeological, architectural, scenic, cultural, and naturallandmark significance, which follows guidance equivalent to that of the National Park Service,is l provided. Contact with local tribal authorities is acceptably documented. A letter from the SHPO i
! addressing any issues related to the properties that might be affected by the facilities is included. The applicant has acceptably demonstrated that the SHPO and tribal authorities agree with the planned I protection from or determination of lack of conflict with facilities and activities and with any places of importance to the State, Federal, or tribal authorities. The applicant has acceptably rated the aesthetic and scenic quality of the site in accordance with the BLM Visual Resource Inventory and Evaluation System.
Based on the information provided in the application, and the detailed review conducted of the characterization of regional historic, archeological, architectural, scenic, cultural, and natural landmarks near the uranium mill site, the staff has concluded that the information is acceptable and is in compliance with 10 CFR 51.45, which requires a description of the affected environment containing sufficient data to aid the Commission in its conduct of an independent analysis.
2.4 References National Park Service,1973, Preparation ofEnvironmental Statements: Guidelinesfor Discussion of l Cultural (Historic, Archeological, Architectural) Resources, Washington, DC: National Park Service.
l U.S. Bureau of Land Management,1978, Upland Visual Resource Inventory and Evaluation, BLM Manual Section 8411, Washington, DC: U.S. Department of the Interior.
U.S. Nuclear Regulatory Commission,1982, " Standard Format and Content of License Applications, t Including Environmental Reports, for In Situ Uranium Solution Mining" (SFCG), Regulatory I
Guide 3.46. Washington, DC: U.S. Nuclear Regulatory Commission, Office of Standards Development.
3.0 Endangered Species Act G-3 NUREG-1620 t
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I 3.1 Consultation Process
'The specific approach that should be used in performing the ESA, Section 7 consultation are outlined in 50 CFR Part 400. Consistent with this regulation, the NRC must determine if any proposed actions could impact endangered species or their habitats. These are listed in 50 CFR Part 17. The purpose of the consultations is to insure that any action authorized by NRC wil not likely jeopardize the condnued existence of any endangered species.
In detennining if such consultations are necessary, the NRC staff could take into consideration impacts resulting from excavation of clay used in radon barrier construction or procurement of rocks used in rip rap. Other surface reclamation work such as the cleanup of windblown tailings could have the potential to impact endangered animals or plants, and as such the NRC should review 50 CFR Part 17 to determine if any endangered species could be impacted. Consultations would also be necessary for the processing of any alternate concentration limit (ACL) application filed for a site located on or near a river, if that river contains endangered species. Because of this, it is important that the NRC staff use the information found in 50 CFR Part 17 to determine if any etidangered species can be found at the site, or possible locations of borrow areas or rock sources to assess if any endangered species could be impacted.
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'e b v.* l NRC FORM 335 u.s. NUCLEAR REGULATORY coMMiss!ON 1. AEPoRT NUM1ER p 89) (Assegned by NRC, Add Vol.. Supp., Rev.,
NRCM 1102. and Addendum Numbers, N any.)
22o1. 22c2 BIBLIOGRAPHIC DATA SHEET (see mauuccons on u,e rsei NUREG-1620
- 2. TITLE AND SUBTITLE DRAFT Dr;ft Standard Review Plan for the Review of a Reclamation Plan for Mill Tailings Sites Under 3. DATE REPORT PUBLISHED Title il of the Uranium Mill Tailings Radiation Control Act: Draft Report for comments MONTH YEAR January 1999
- 4. FIN oR GRANT NUMBER
- 6. AUTHOR (S) 6. TYPE of REPORT Draft I
- 7. PERIOD COVERED (inesusve Deres) 8 PEAFoRMINbRGANIZATioN - NAME AND ADDRESS (# NRC. ponoe Owson, omco or Regen, u s Nucear Regulatory commasa, ana mmeng address, a contracror j prowar narre and mssng aaareas >
Division of Waste Management Office of Nuclear Material Safety and Safeguards i
) U.S. Nucleer Regulatory Commission l W;shington, DC 20555-0001
- 9. SPONSORING ORGANIZATION - NAME AND ADDRESS (#NRc, type 'Same as anove'. # contracror, powar NRc Desen. omce or Reg,on u S Nucear Repuiawy Comasson, and maeng actfress)
Same as 8 above l
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- 10. SUPPLEMENTARY NOTES
- 11. ABSTRACT (200 was or ess)
A Nuclear Re ulatory Commission source and byproduct material license is required, as per 10 CFR Part 40, for the operation
{ of uranium mi s and disposition of tailings or wastes produced by the extraction or cor.:antration of source material from ores l processed primarily for their source material. Appendix A to Part 40 establishes technical and other criteria relating to siti'ig, I operation, decontamination, decommissioning, and reclamation of mills and tailings at mill sites. The licensee's site reclamation plan documents how the proposed activities demonstrate compliance with the enteria in Appendix A to Part 40 and the information needed to prepare the environmental report on the effects of the proposed reclamation activities on the health and safety of the public and on the environment.
The Standard Review Plan (SRP)is for the guidance of staff reviewers, in the Office of Nuclear Material Safety and Safeguards, in performing safety ano environmental reviews of reclamation plans for Title 11 uranium recovery sites. It provides guidance for new reclamation plans, renewals, and amendments. The principal purpose of the SRP is to assure the quality cnd uniformity of staff reviews and to present a well-defined base from which to evaluate changes in the scope and requirements of a review.
The SRP is wntten to cover a wide variety of site conditions and reclamation plans. Each section is written to provide a description of the areas of review, review procedures acceptance enteria, and evaluation of findings.
13 Ava,lLABILITY slATEMLNT
- 12. KEY WoRDS/DESCRIPToRS rust worps or parases that m# ass,st researchers m beatmp the report) unlimited Title 11 sites, tailings, reclamation plans, closure activity, license amendments, license renewals, financial surety, license termination, long-term surveillance. 14 stCURITY CLASstFICATION l lhs Page) unclassified (hs Report) unclassified i
- 15. NUMBER OF PAGES l
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