ML16326A447
| ML16326A447 | |
| Person / Time | |
|---|---|
| Site: | Texas A&M University |
| Issue date: | 11/21/2016 |
| From: | Mcdeavitt S Texas A&M Univ |
| To: | Alexander Adams, Patrick Boyle Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 2016-0059 | |
| Download: ML16326A447 (60) | |
Text
Nuclear Science Center 1095 Nuclear Science Road, 3575 TAMU College Station, TX 77843-3575 Tel. (979) 845-7551 1
NUCLEAR SCIENCE CENTER Dr. Sean M. McDeavitt Director, TEES Nuclear Science Center Texas A&M University Texas A&M Engineering Experiment Station 1095 Nuclear Science Road, 3575 TAMU College Station, TX 77843-3575 November 21, 2016 2016-0059 Docket Number 50-59 / License No. R-23 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Ref: 10 CFR 50.90
SUBJECT:
License Amendment Request for the Approval of the Unrestricted Release of the Zachry Engineering Center and Changes to the AGN-201M Facility License No. R-23, Docket 50-59, Technical Specification Sections 5.2 and 5.3 Attn: Mr. Alexander Adams Jr., Chief, Research and Test Reactors Branch Office of Nuclear Reactor Regulation Mr. Patrick M. Boyle, Project Manager, Research and Test Reactors Branch Office of Nuclear Reactor Regulation Texas A&M University (TAMU) is proposing this license amendment request (LAR) to Operating License No. R-23, Docket 50-59 seeking U.S. Nuclear Regulatory Commission (U.S. NRC) approval for the unrestricted release of the Zachry Engineering Center located on the TAMU Campus. The Zachry Engineering Center is a currently-licensed location for the AGN-201M reactor. The approval of this LAR will result in the removal of the Zachry site from the R-23 license.
Further, TAMU proposes to remove the requirement to maintain an Emergency Plan and Physical Security Plan as a license condition from the R-23 license. The material possession levels at the AGN-201M site have been and will be below the regulatory requirements for having a Physical Security Plan.
For clarity, let me state that there are two license holders involved in recent relevant licensing actions preceding this current request. The first is TAMU, the licensee for the AGN-201M reactor that is the subject of this present LAR (Facility License No. R-23, Docket 50-59). The second is the Texas A&M Engineering Experiment Station (TEES), the licensee for the TEES Nuclear Science Center (NSC) 1 MW TRIGA reactor (Facility License No. R-83, Docket 50-128). Both TAMU and TEES are members of the Texas A&M University System (TAMUS), but TAMU is one of eleven academic members and TEES is one of seven state agency members; they have distinct legal standing within
Nuclear Science Center 1095 Nuclear Science Road, 3575 TAMU College Station, TX 77843-3575 Tel. (979) 845-7551 2
NUCLEAR SCIENCE CENTER the TAMUS.
On October 14, 2015, an LAR was submitted by TEES (U.S. NRC ADAMS Accession No. ML15287A148) to modify license R-83 to enable the relocation and safe storage of the AGN-201M special nuclear material on the NSC site; this LAR was approved by the U.S. NRC on August 31, 2016 (ADAMS Accession No. ML16109A153). Following this approval, the AGN-201M SNM was packaged, transported, and placed into storage under the conditions outlined in the amended Facility License No. R-83. All SNM was removed from the Facility License No. R-23 at that point.
On November 11, 2015, an LAR was submitted by TAMU (U.S. NRC ADAMS Accession No. ML15315A027) to modify license R-23 to enable to storage of the AGN-201M reactor tank, control console, and associated components either at the current Zachry Engineering Center location or at the TEES NSC site in designated storage areas; this LAR was approved by the U.S. NRC on October 14, 2016 (ADAMS Accession No. ML16278A497). Following this approval, the AGN-201M reactor tank and associated components were packaged, transported and placed into their proper storage locations at the NSC facility where they will be stored for up to 5 years. In that time, TAMU and TEES will work toward the establishment of a new AGN facility to enable the reassembly and operation of the AGN-201M reactor. The reactor tank and associated components are now stored at the NSC under the conditions outlined in the amended Facility License No. R-23.
The following are the enclosures and attachment accompanying this letter:
contains the justification for unrestricted release of the Zachry Engineering Center; the no significant hazards consideration determination and the environmental consideration associated with the unrestricted release of the Zachry Engineering Center.
(attached to Enclosure 1) contains proposed modifications to page 3 of Facility License No. R-23 and the Technical Specifications (TSs) associated with license R-23. The modification to TS Page 15 removes all reference to the SNM storage location and various rooms within the Zachry Engineering Center. (Specifically, TSs 5.2 and 5.3 will be deleted to reflect that the AGN-201M SNM, the reactor, and all associated reactor components have been packaged, transported to, and stored at the NSC.) The modified TS Pages 20 and 21 and modified license page remove all references to the AGN-201M Emergency Plan and Physical Security Plan. (Specifically, license page 3, TSs 6.4.3(b) and 6.6(f) will be changed to remove reference to the AGN-201M Emergency Plan and Physical Security Plan.)
contains the TAMU Final Status Survey Plan, Revision 1 that is to be implemented in support of the unrestricted release of the Zachry Engineering Center. This LAR will be supplemented with the final survey results once they have been completed. It is anticipated that these results will be submitted in December 2016.
Should you have any questions regarding the LAR, please contact me or Mr. Jerry Newhouse at (979) 845-7551 or via email at mcdeavitt@tamu.edu or newhouse@tamu.edu.
Nuclear Science Center 1095 Nuclear Science Road, 3575 TAMU College Station, TX 77843-3575 Tel. (979) 845-7551 3
NUCLEAR SCIENCE CENTER Oath of Affirmation I declare under penalty of perjury that the foregoing is true and correct to the best of my knowledge.
Sincerely, Sean M. McDeavitt, PhD Director, TEES Nuclear Science Center Submitted with Level 2 Delegate Authorization from Dr. Yassin Hassan in letter dated February 8, 2016 (ADAMS Accession No. ML16043A048)
Justification for Unrestricted Release of the Zachry Engineering Center :
Proposed Modifications to AGN-201M License Page 3 and Technical Specification Pages 15, 20, and 21 (Attached to Enclosure 1) :
Final Status Survey Plan, Revision 1 (previously submitted, included for clarity)
CC: next page
Nuclear Science Center 1095 Nuclear Science Road, 3575 TAMU College Station, TX 77843-3575 Tel. (979) 845-7551 4
NUCLEAR SCIENCE CENTER cc:
William Dean, Office Director United States Nuclear Reactor Commission Office of Nuclear Reactor Regulation Michael Young, President Texas A&M University 1246 TAMU College Station, TX 77843-1246 Dr. M. Katherine Banks, Vice Chancellor and Dean Dwight Look College of Engineering 3126 TAMU College Station, TX 77843-3126 Dr. Yassin Hassan, Department Head, Nuclear Engineering Texas A&M University Nuclear Engineering Department 3133 TAMU College Station, TX 77843-3133 Dr. John Hardy Reactor Safety Board Chairman Texas A&M University 3255 TAMU College Station, TX 77843-3255 Dr. Latha Vasudevan Radiological Safety Officer, Texas A&M University Environmental Health and Safety 1111 Research Parkway College Station, TX 77843-4472 Jerry Newhouse NSC Assistant Director Texas A&M Engineering Experiment Station 3575 TAMU College Station, TX 77843-3575 Scott Miller NSC Manager of Reactor Operations Texas A&M Engineering Experiment Station 3575 TAMU College Station, TX 77843-3575 Jeremy Osborn AGN-201M Reactor Supervisor Texas A&M University Nuclear Engineering Department 3133 TAMU College Station, TX 77843-3133
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ENCLOSURE 1 TEXAS A&M UNIVERSITY FACILITY LICENSE R-23, DOCKET NO. 50-59 AMENDED FACILITY OPERATING LICENSE AGN-201M REACTOR JUSTIFICATION FOR THE UNRESTRICTED RELEASE OF THE ZACHRY ENGINEERING CENTER
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1.0 ABBREVIATIONS AND SYMBOLS The following is a list of abbreviations, symbols, and units used in Enclosure 1:
ABBREVIATIONS:
ADAMS Agencywide Documents Access and Management System AEC Atomic Energy Commission AGN-201M Aerojet General Nucleonics Model 201-Modified ALARA As Low As Reasonably Achievable ANSI American National Standards Institute CFR Code of Federal Regulations DQOs Data Quality Objectives FSS Final Status Survey LAR License Amendment Request MARSSIM Multi-Agency Radiation Survey and Site Investigation Manual MDC Minimum Detectable Concentrations NSC Texas A&M Engineering Experiment Station Nuclear Science Center NUREG US Nuclear Regulatory Commission Regulation SNM Special Nuclear Material TAMU Texas A&M University TEDE Total Effective Dose Equivalent TEES Texas A&M Engineering Experiment Station TRIGA Training, Research, and Isotope Production, General Atomics TS Technical Specification U.S. NRC United States Nuclear Regulatory Commission SYMBOLS:
Alpha Beta Gamma
µ Micro Less than Percent k/k Reactivity
°C Celsius 14C Carbon 14 41Ar Argon 41 UO2 Uranium Dioxide PuBe Plutonium-Beryllium UNITS:
s Second h
Hour y
Year cm Centimeter dpm Disintegrations Per Minute Ci Curie R
Roentgen rem Roentgen Equivalent Man mrem Millirem
µrem Microrem rad A Unit of Absorbed Radiation Dose mSv Millisieverts
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2.0 INTRODUCTION
Texas A&M University (TAMU) owns and operates the AGN-201M reactor (Facility License No.
R-23, Docket No. 50-59). Per the recent license amemndment to Facility License No. R-23 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML16278A497), the licensed locations for the AGN-201M are in the Zachry Engineering Center and the TEES Nuclear Science Center (NSC); the NSC site is approved for storage only. On October 15, 2016, TAMU completed a project to defuel, disassemble, package, and transport the AGN-201M SNM, reactor, and associated components from the Zachry Engineering Center to the NSC site and the Zachry site is now empty.
There are two license holders involved in recent relevant licensing actions preceding this document. The first is TAMU, the licensee for the AGN-210M reactor that is the subject of this present LAR (Facility License No. R-23, Docket 50-59). The second is TEES, the licensee for the NSC 1 MW TRIGA reactor (Facility License No. R-83, Docket 50-128).
On October 14, 2015, an LAR was submitted by TEES (ADAMS Accession No. ML15287A148) to modify license R-83 to enable the relocation and safe storage of the AGN-201M SNM on the NSC site; this LAR was approved by the U.S. NRC on August 31, 2016 (ADAMS Accession No. ML16109A153). On November 11, 2015, an LAR was submitted by TAMU (U.S. NRC ADAMS Accession No. ML15315A027) to modify license R-23 to enable to storage of the AGN-201M reactor tank, control console, and associated components at the TEES NSC facility in designated storage areas; this LAR was approved by the U.S. NRC on October 14, 2016 (ADAMS Accession No. ML16278A497). These approvals enabled TAMU to transport and store the AGN-201M SNM, reactor, and associated components at the NSC facility.
The AGN-201M SNM is now stored in the NSC fuel storage vault. The reactor tank and components are stored in the accelerator building and a cargo container on the NSC site. The reactor tank is stored in a defueled and drained condition and all associated components are stored in secured locations. The NSC license was amended to allow temporary storage for a period not to exceed 5 years to enable TAMU to establish a new site in which to operate the reassembled AGN-201M reactor.
The purpose of this LAR is threefold: First, TAMU requests approval from the U.S. NRC for the unrestricted release of the Zachry Engineering Center. TAMU has prepared this LAR in accordance with Chapter 17 of the NUREG-1537 Part 1, Guidelines for Preparing and Reviewing Applications for Licensing of Non-Power Reactors. The AGN-201M license and applicable TSs will remain active while the AGN-201M SNM, reactor, and associated components are stored at the NSC facility.
Second, as part of the unrestricted release, TAMU proposes the deletion of TS Sections 5.2 and 5.3 to reflect that the AGN-201M SNM, reactor, and all associated reactor components have been packaged, transported and stored at the NSC site. The AGN-201M SNM, reactor, and associated components no longer exist in the Zachry Engineering Center. Justification for the proposed TS changes is in Enclosure 1 (this document). Attachment 1 to this enclosure contains the new proposed TS page 15.
Third, TAMU requests the AGN-201M license reference to the Physical Security Plan and associated TSs reference to the AGN-201M Physical Security Plan and Emergency Plan be removed from the AGN-201M TSs. The material possession levels at the AGN-201M site have
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been and will be below the regulatory requirements for having a Physical Security Plan and Emergency Plan. Attachment 1 contains the new proposed TS pages and license page 3. (See Section 5.13 for details on this matter.)
Currently, all SNM formerly associated with license R-23 has been transferred to license R-83 and is now protected under the Physical Security Plan for R-83. The Physical Security Plan for R-83 was approved by the U.S. NRC as part of the license renewal process completed in October 2015. Since the R-83 Physical Security Plan has been approved by the U.S. NRC, this SNM transfer does not decrease the effectiveness of the protection of the SNM as described in 10 CFR 50.54(p).
3.0 BACKGROUND
On August 26, 1957, the Atomic Energy Commission (AEC) issued an operating license to TAMU for the operation of the AGN-201M reactor. The original location of the AGN-201M Reactor was in the Mechanical Engineering Shops in Thompson Hall on the TAMU campus. On November 3, 1970, TAMU submitted a LAR to the AEC requesting approval to disassemble, package, transport, and reassemble the AGN-201M reactor in the newly constructed Zachry Engineering Center. The AEC approved this LAR and issued Amendment 9 to the AGN-201M License on February 4, 1972. The Zachry Engineering Center became the licensed location of the AGN-201M reactor at TAMU.
Radiological surveys performed over the operating history of the AGN-201M reactor have identified no contamination over release limits in the reactor areas of Zachry Engineering Center.
In addition, recent surveys conducted during reactor disassembly and in support of the removal, packaging, and transport of the SNM have identified no contamination over release limits on the reactor external surfaces or on reactor internal component surfaces (e.g., in the core tank, on control rod drive thimbles that pass through the unclad fuel disks, and on the lower core plate).
(Enclosure 2 of this document contains the Final Status Survey (FSS) Plan, Revision 1 associated with the unrestricted release of the Zachry Engineering Center; it describes the procedures to be followed to certify the Zachry site is not measurably contaminated.) This LAR will be supplemented with the final radiological survey results once they are collected. It is anticipated that the final survey results will be submitted in December 2016. Successful results from the FSS will demonstrate compliance with U.S. NRC regulations and guidance in support of the unrestricted release of the Zachry Engineering Center.
As a final point of background for this LAR, it is notable that TAMU instigated the relocation of the AGN-201M reactor as part of a much larger-scale project wherein the Zachry Engineering Center is being completely renovated and repurposed. The expansion project required the transport and temporary storage of the AGN-201M SNM, reactor, and associated components from the Zachry Engineering Center to the NSC site. By letter dated April 15, 2015 (ADAMS Accession No. ML15183A462), TAMU provided an overview of the entire project to the U.S. NRC. In the letter, TAMU specifically committed to operating the AGN-201M reactor in the future, and as such, committed to construct or modify a facility to house the AGN-201M reactor within or adjacent to the NSC site. In the near future, TAMU anticipates submitting a construction permit application to the U.S. NRC requesting approval to proceed.
As noted briefly in Section 2.0, the relocation project required two LARs be submitted to the U.S.
NRC for approval in order to relocate the AGN-201M SNM, reactor, and associated components.
The first LAR was submitted from TEES to the U.S. NRC by letter dated October 14, 2015
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(ADAMS Accession No. ML15287A148), as supplemented. The October 14, 2015 LAR and supplements requested U.S. NRC approval of changes to the TEES License and TSs (Facility License No. R-83, Docket No. 50-128) to receive and possess the AGN-201M fuel and SNM in the NSC fuel storage vault for a period of up to 5 years. On August 31, 2016 (ADAMS Accession No. ML16109A153), the U.S. NRC issued Amendment 18 to the NSC operating license approving the changes to the NSC License and TSs. The AGN-201 M fuel and SNM have been transported and stored at the NSC facility.
The second LAR was submitted to the U.S. NRC on November 11, 2015 (ADAMS Accession No. ML15315AA027). This LAR and supplements requested U.S. NRC approval to transport and store the AGN-201M reactor and associated components in secured locations at the NSC facility for a period up to 5 years. On October 14, 2016 (ADAMS Accession No. ML16278A497), the U.S. NRC issued Amendment 15 to the AGN-201M operating license approving the changes to the AGN-201M License and TSs. The AGN-201M reactor and associated components have been transported and stored at the NSC site.
This LAR represents the final step in the regulatory process associated with the AGN-201M relocation project. In short, TAMU is requesting approval from the U.S. NRC for the unrestricted release of the Zachry Engineering Center. The substance of this LAR is focused on detailed activities to be undertaken by TAMU to accomplish this unrestricted release.
4.0 REGULATORY EVALUATION
The AGN-201M SNM, reactor, and components have been moved to and stored at the NSC. No contamination was identified during the move. The licensed site at the Zachry Engineering Center is now being controlled until the FSS plan is implemented and this LAR is approved. TAMU is now seeking U.S. NRC approval for the unrestricted release of the Zachry Engineering Center.
TAMU developed an FSS plan (Enclosure 2) which details the process to be implemented to meet the criteria required to achieve the unrestricted release of the Zachry Engineering Center. It is expected that this LAR will be supplemented in December 2016 with the FSS results to justify the unrestricted release of the Zachry Engineering Center.
This LAR and the FSS plan were prepared using the guidance and format specified in Chapter 17 of NUREG-1537. The radiological criteria for the unrestricted release of the Zachry Engineering Center is set forth in 10 CFR 20.1401. The FSS plan was developed and will be administered per the applicable sections of the following regulations and regulatory guidance documents:
Code of Federal Regulations 10 CFR 19 Notices, Instructions and Reports to Workers 10 CFR 20 Standards for Protection Against Radiation 10 CFR 30 Rules of General Applicability to Domestic Licensing of Byproduct Material 10 10 CFR 50 Domestic Licensing of Production and Utilization Facilities 10 CFR 51 Licensing and Regulatory Policy and Procedures for Environmental Protection U.S. NRC Regulatory Guides 1.86 Termination of Operating Licenses for Nuclear Reactors (Withdrawn)
(Note: this withdrawn Guide is referenced because it contains a table of surface contamination values that is still contained in 25 Texas Administrative Code §289.202(ggg)(6), Acceptable Surface Contamination Levels and are applicable to State-licensed activities at TAMU.)
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8.21 Health Physics Surveys for Byproduct Material at NRC-Licensed Processing and Manufacturing Plants 8.30 Health Physics Surveys in Uranium Recovery Facilities NUREG - Publications 1505 A Nonparametric Statistical Methodology for the Design and Analysis of Final Status Decommissioning Surveys 1507 Minimum Detectable Concentrations with Typical Radiation Survey Instruments for Various Contaminants and Field Conditions 1537 Guidelines for Preparing and Reviewing Applications for Licensing of Non-Power Reactors 1575 Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) Facilities 1757 Consolidated Decommissioning Guidance The FSS Plan, Revision 1 was developed in accordance with appropriate sections of above NRC guidance documents. The primary purpose of conducting surveys is to demonstrate that the former AGN-201M site within the Zachry Engineering Center satisfies U.S. NRC criteria for unrestricted release. Also, satisfying U.S. NRC criteria will assist the State of Texas Department of State Health Services, and Texas A&M University Radiological Safety, Environmental Health and Safety in supporting the unrestricted release. By satisfying these criteria, the remaining structure can be reused without radiological restrictions. The design of the AGN-201M reactor precludes the possibility of groundwater or soil contamination as there are no external cooling loops, coolant cleanup systems, or irradiation loops. Further, there are no radioactive waste processing systems (e.g., waste compaction, liquid waste treatment, or contaminated off gas treatment systems). Accordingly, the FSS (Enclosure 2) does not address soil or groundwater sampling.
Texas A&M University will comply with the requirements of 10 CFR 20.1402 for the radiological criteria for the unrestricted release of the Zachry Engineering Center. In accordance with this rule, the site will be considered acceptable for unrestricted use if the residual radioactivity that is distinguishable from background radiation results in a TEDE to an average member of the public that does not exceed 25 mrem (0.25 mSv) per year. Although no contamination has been detected on any surfaces or components during extensive surveys conducted in support of defueling and during earlier scoping surveys, TAMU commits to using the default screening values for surface contamination as presented in Appendix H to NUREG-1757, Volume 2, Revision 1, as upper limits for the project. Site characteristics support the use of these values as only superficial surface contamination is expected. There are no buried pipes or potentially contaminated structures, and no unusual radionuclides are anticipated. The screening values have been determined by the U.S. NRC to be ALARA and no further analyses are required (Appendix N to NUREG-1757).
TAMUs self-imposed release criteria are more limiting (contamination is not to exceed twice background, using appropriate instrumentation) and determined by the TAMU radiological safety program.
NUREG-1537 Section 17.1.4 will be used by TAMU. The following are the criteria to be used to release the Zachry Engineering Center for unrestricted use:
- 1. a) No more than 5 µrem per hour above background at 1 meter from the surface measured for indoor gamma radiation fields from concrete, components, and structures, or,
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b) No more than 10 mrem per year for gamma emitters above background absorbed dose to any person, considering reasonable occupancy and proximity.
- 2. Residual surface contamination limitations consistent with Regulatory Guide 1.86.
Regulatory Guide 1.86 was withdrawn by U.S. NRC, effective August 12, 2016, although similar numerical guidance remains in Regulatory Guides 8.21, and 8.30. The table of surface contamination values in RG 1.86 has been retained for this project as these values are also contained in 25 Texas Administrative Code §289.202(ggg)(6) Acceptable Surface Contamination Levels and are applicable to State-licensed activities at TAMU.
The TAMU radiological safety program has a policy of no detectable activity for unrestricted use and release. No detectable activity is interpreted by TAMU as not exceeding twice the background level. For direct radiation levels, the TAMU EHS criteria of less than twice background will be established by confirming that dose rates from any residual licensed material are no more than twice background levels at 1 meter from the surface consistent with the previously noted guidance from NUREG-1537. Surface contamination levels will be evaluated relative to background data presented in instrument manufacturers technical literature and using field measurements. Meeting the TAMU Radiological Safety criteria for release will also satisfy U.S. NRC requirements. This demonstrates conservatism in the TAMU program for unrestricted release.
NUREG-1575 defines impacted areas as those with a possibility of residual radioactivity in excess of background levels. Radiological surveys of impacted areas are required to demonstrate that established criteria have been satisfied. Non-impacted areas are those with no reasonable expectation of residual contamination; no surveys of non-impacted areas are required. Impacted areas are classified by contamination potential as follows:
Class 1: Areas that have, or had prior to remediation, a potential for radioactive contamination (based on site operating history) or known contamination (based on radiological surveys) expected to be in excess of established unrestricted release criteria.
Class 2: Areas that have, or had prior to remediation, a potential for radioactive contamination or known contamination, but are not expected to exceed established criteria.
Class 3: Areas that are potentially impacted but are not expected to contain any residual radioactivity, or are expected to contain levels of residual activity at a small fraction of the established criteria, based on site operating history and previous radiological surveys.
Based upon extensive survey experience in the building and due to the acceptance criteria being very close to background, TAMU finds it is appropriate to use the Scenario B Null Hypothesis, as presented in NUREG-1505. This scenario assumes the facility is acceptable for release if the alternative hypothesis (i.e., it is contaminated) is rejected. All static survey points and scans must not exceed twice background to pass. No statistical treatment of the survey data is required.
Implementing the FSS plan, developed in accordance with NRC regulatory guidance will demonstrate conditions for the unrestricted release of the Zachry Engineering Center in accordance with Subpart E of 10 CFR 20, Radiological Criteria for License Termination, thus allowing building renovations to proceed without radiological safety constraints.
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5.0 TECHNICAL EVALUATION
5.1 FSS Plan Synopsis Texas A&M University prepared a comprehensive FSS plan which is presented in Enclosure 2.
With the removal of the reactor and any known radioactive materials and components associated with AGN-201M reactor operations from the Zachry Engineering Center, the FSS plan may now be implemented to demonstrate that residual radiological conditions satisfy U.S. NRC criteria for future unrestricted uses of the facility. This FSS plan will be implemented in accordance with U.S.
NRC recommended guidance as presented in NUREG-1575, and NUREG-1757. The process emphasizes the use of Data Quality Objectives and Data Quality Assessment. The graded approach methodology will be followed to ensure survey efforts are maximized in those areas having the greatest potential for residual contamination.
Based upon the self-contained design of the AGN-201M reactor, TAMU operating procedures, and thorough survey work performed in preparation for and during reactor disassembly and defueling work, the Zachry Engineering Center meets the NUREG-1757, Vol 1 description of a Group 2 decommissioning. Screening values are applicable (no surface contamination or activation of structures has been identified), no liquid, solid, or particulate effluents were routinely generated, and there are no pathways for soil or groundwater contamination.
The radiological dose criterion of <25 mrem/y specified in 10 CFR 20.1402 will be the basis for unrestricted release. To date, no surface contamination has been identified in the facility and no activation products have been identified in volumetric sampling of reactor shielding and the building structure and only trace levels of contamination have been found on reactor internals (including components in contact with the reactor fuel). The lack of detectable surface contamination prevents selection of a default radionuclide of concern. However, the selected survey instruments exhibit MDCs for commonly encountered radionuclides that are well below the Default Screening Values presented in Table 1 of Appendix H to NUREG 1757, Volume 2, Revision 1. The screening values are upper limits for the project, and are based upon conservative exposure pathway considerations and have been determined by the U.S. NRC to meet the ALARA criteria for release. No further ALARA analysis is required. It was determined by ongoing site surveys that no specific radionuclide contamination can be identified and there is no potential for fission product contamination. Therefore, the conservative screening value for 60Co has been chosen as the upper limit for release surveys.
Impacted surfaces have been classified (Class 1, 2, or 3) by contamination potential and those surfaces further subdivided into survey units. The process for classification and survey unit identification is described in NUREG-1575, Sections 4.4 and 4.6. Because each survey point must not exceed the screening values (and the more limiting TAMU constraint of not exceeding twice the background levels), no statistical tests are required.
The FSS plan presents the applicable release criteria, categorization of areas for survey work, survey methodology and instrumentation, and survey data evaluation. The FSS plan will be implemented, the results will be analyzed, and a summary submitted to the U.S. NRC.
5.2 Facility Description The AGN-201M reactor is an educational research reactor formerly located on the TAMU campus in the Zachry Engineering Center (Fig. 1). The reactor was first assembled in 1957 and began
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operation in Thompson Hall before it was relocated to the Zachry site in 1972. As noted above, the AGN-201M reactor has been dismantled and the SNM, reactor tank and all related components have been relocated to the NSC facility according to the provisions in the amended R-23 and R83 Facility Operating Licenses. The Zachry site described here is the location to be surveyed for unrestricted release under this LAR.
The location in the Zachry Engineering Center allowed for the complete isolation of the reactor room from the remainder of the building. Also, the AGN reactor room was designed with approximately 3-foot thick reinforced concrete walls, ceilings and floors. Floor areas were covered with tile identified to be asbestos containing material.
Over the past 59 years TAMU students in the Department of Nuclear Engineering used the reactor for educational experiments and applications and graduate students occasionally used the reactor for research purposes. The reactor has not been operated since 2014. The AGN-201M reactor area on the former Ground Floor is divided into 3 rooms (Fig. 2):
- 1. Room 60C Office/Control point area with minimal potential for contamination.
- 2. Room 61A Safeguards Laboratory, a small laboratory used for research.
- 3. Room 61B Reactor Room, housing the reactor, shielded control area, and storage.
The First Floor area (Room 135 in Fig. 3) is a single large room designed with removable concrete shield plugs in the floor to allow access to the top of the reactor. This room was used extensively for unrelated ion beam accelerator work, which limited access to the top (thermal column) of the reactor.
5.3 Operating History Over the past 59 years the AGN-201M reactor has experienced numerous intermittent periods in which the reactor was not operational. It is noteworthy that the reactor was relocated in the early 1970s to the Zachry Engineering Center and began operation in 1972 with a maximum thermal power rating of 5 watts.
From 1957 to the present, based upon its documented power history and using estimated data, a total of approximately 2 x 1017 fissions have occurred in the AGN-201M fuel. Accordingly, the fuel has not been significantly depleted and fission product content is negligible.
From 1972 through to the present, power operation of the AGN-201M reactor has produced approximately 1.3 kilowatt-hours of energy. Logs document approximately 1,400 total operating hours with an average power level of approximately 0.93 watts. The reactor has not operated since 2014 and has only logged 142 operating hours since the 1999. The very low fission product content was confirmed during the recent defueling work; measured levels close to contact with the fuel disks were <2 mrem/h gamma dose rate and approximately 60 mrad/h beta dose rate.
As noted above, all SNM has been packaged, transported, and stored at the NSC facility.
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Figure 1. Map of Texas A&M Campus, indicating location of Zachry Engineering Center.
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Figure 2. Ground Floor Layout. (Main 61 Area Rooms: ~27 ft by ~48 ft)
Figure 3. First Floor Layout. (Room135: ~27 ft by ~48 ft)
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5.4 Reactor Description (When Assembled)
TAMUs AGN-201M and all other AGN-201M reactors are described by the reactor description given in the original Aerojet-General Nucleonics AGN-201M reactor report (Hazard Report and Preliminary Design Report by Aerojet-General Nucleonics, Docket F-40). The reactor is a free standing unit as depicted in Fig. 4.
Figure 5 presents a cutaway schematic of the AGN-201M design. Key components and safety features are identified. The AGN-201M reactor is designed to use homogenous polyethylene-UO2 fuel plates with graphite reflectors. The reactor is equipped with one thermal column, eight access ports, and one glory hole through the core tank. The reactor fuel is sealed in a gas-tight aluminum tank surrounded by a graphite reflector, lead shield, and large water shield tank. The water shield is designed to eliminate fast neutron release from the system. During operation, heat flows from the core through the graphite reflector and the lead shield into the tank of water that surrounds the reactor core. An external heat sink is not required since the reactor power level is so low.
The maximum neutron fluence rate is 2.4 x 108 n/cm2-s at 5 watts. This power level was approved by the AEC in Amendment No. 10 to License R-23 issued on January 18, 1973. Excess reactivity is approximately 0.137% k/k (empty glory hole), and the design has a temperature coefficient of
-0.024% k/k per degree C.
Ventilation for power operation was provided by a roof-mounted blower connected to a high efficiency particulate filter box in the accelerator room above the reactor room (Fig. 3). A grate in the floor of the accelerator room provided a flow path for air from the reactor room. All airflow from the reactor room was dispersed in the accelerator room before discharge via the filtered collector inlet in a corner of the accelerator room. No real-time stack monitoring equipment was provided, as effluents (e.g., 41Ar) were negligible.
5.5 Planned Activities for the Unrestricted Release of the Zachry Engineering Center Important basic tasks to support TAMUs efforts in achieving unrestricted release of the Zachry Engineering Center included 1) removal of the AGN-201M SNM, reactor, and associated components in preparation for general cleanup of the facility and 2) development and continued implementation of the FSS Plan. The project is not a decommissioning project since the AGN-201M reactor and associated components have been placed in temporary storage with no disposal of reactor equipment or SNM. No contamination has been identified in the facility. No significant radioactive waste volumes have been generated to date. Significant contamination is not anticipated as building clean-up progresses. Contamination surveys and core sampling to date show no detectible surface contamination over background, and no activation products detected in core samples.
Since the AGN-201M SNM, reactor tank, associated components, and all floor tiles have now been removed, initial floor surveys were completed. Concrete cores were extracted from the floor directly under the former site of the reactor pedestal and laboratory analysis did not detect the presence of activation products. Calculations based upon power history and observed neutron dose rate along with sample data from concrete shield blocks removed from around the reactor skirt also support the conclusion that there has been no detectable activation of the concrete building structure.
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Figure 4. AGN-201M Reactor.
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Figure 5. Cut-away View of AGN-201M Reactor 5.6 Organization and Roles and Responsibilities The TAMU senior (Level 2) manager for oversite of the entire AGN-201M relocation project is Dr.
Sean M. McDeavitt, Director of the TEES Nuclear Science Center, as delegated by the Department Head of Nuclear Engineering, Dr. Yassin Hassan (see Table 1). Dr. McDeavitt holds level 2 management authority for the TEES NSC Facility License No. R-83 and delegated level 2 management authority for the TAMU AGN-201M Facility License No. R-23.
Dr. McDeavitt ultimately reports to Dr. M. Katherine Banks, Vice Chancellor and Dean of Engineering for the Texas A&M University System (TAMUS), Dean of the TAMU College of Engineering, and the Director of TEES. Dr. Banks holds Level 1 management authority for the TEES NSC Facility License No. R-83 and shares level 1 management authority for the TAMU AGN-201M Facility License No. R-23 with the President of Texas A&M University, Michael K.
Young.
Table 1 presents additional information describing the list of responsible individuals or groups and their respective roles within the project:
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Table 1. Responsible Individuals/Groups and Roles in the AGN-201M Relocation Project Role Michael Young, TAMU President Level 1 management authority over the AGN-201M operating license (R-23).
Regulatory responsibility for the AGN-201M Dr. M. Katherine Banks, TAMUS Vice Chancellor and Dean of Engineering, TAMU Dean, College of Engineering, and Director of TEES Shared Level 1 management authority over the AGN-201M operating license (R-23).
Dr. Stuart Anderson, Assistant Vice Chancellor for Facilities Planning and Management Direct leadership of the Zachry renovation project, AGN relocation project for TEES.
Reports to Level 1 management for both operating licenses (R-23 and R-83).
Dr. Yassin Hassan, Head, Nuclear Engineering Department Level 2 management authority on the AGN-201M operating license (R-23)
Dr. Sean M. McDeavitt, Director, TEES Nuclear Science Center AGN Relocation Activity Coordinator for TAMU and TEES (April 2015).
Delegated Level 2 management authority on the AGN-201M operating license (R-23) from Dr. Y.
Hassan. (Delegation letter dated Jan. 22, 2016 - NRC ADAMS No. ML16043A048)
Level 2 management authority for the NSC TRIGA operating license (R-83).
TEES Reactor Safety Board (Dr.
John Hardy, Chair)
The Reactor Safety Board (RSB) has internal oversight and regulatory compliance authority over both the NSC TRIGA and AGN-201M reactors, per provisions within the NRC licensing documents (i.e.,
TRIGA and AGN technical specifications).
The RSB has jurisdiction for the technical review or concurrence approval for primary communications with the Nuclear Regulatory Commission regarding the licensing, technical, and safety issues for the NSC TRIGA and AGN-201M reactors.
When needed, the RSB relies on the expertise of the Radiological Safety Committee (RSC) or external consultants to provide expert review of matters under its jurisdiction.
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TAMU Radiological Safety Committee (Dr.
John
- Poston, Chair)
The RSC advises the TAMU administration on matters related to radiological safety and recommends policies and procedures to ensure an adequate radiological safety program.
The RSB will rely on the RSC for review of matters related to radiological safety as part of this relocation project; this includes the review of site decontamination plan.
ReNuke Services, Inc. (Oak Ridge, TN)
Rich Werdann, Project Manager ReNuke Services (renuke.com) is an external contractor tasked with managing the relocation project to move the AGN-201M to the NSC site.
ReNuke will work with the Director of the Nuclear Science Center, RSB, RSC, and other necessary individuals and groups to achieve the successful relocation of the AGN-201M to the NSC site.
Reports to Stuart Anderson and coordinates activity with Sean McDeavitt 5.7 Dose Estimate All project personnel frequently accessing the reactor rooms or engaged in the direct handling of radioactive material have been and will continue to be monitored under the TAMU personnel monitoring program (Landauer Luxel dosimeters as the dosimeter of record). General area exposure rates in the reactor room were approximately 10 to 15 µR/h near the defueled reactor.
Maximum exposure rates of up to 50 mrem/h were observed during removal and leak testing of the 1 Ci 239PuBe neutron start-up source. This was a brief task (15 minutes) and effectively removed the largest exposure potential from the project. The source is now in shielded storage at the TEES NSC along with all of the AGN-201M SNM. Total project occupational collective dose is expected to be <120 mrem TEDE. The maximum occupational dose to any project employee is not expected to exceed approximately 50 mrem over the duration of planned activities. This very low dose value represents a small fraction of the 620 mrem National Council on Radiation Protection and Measurements estimated average U.S. annual radiation dose per person.
5.8 Data Collection and Data Evaluation Extensive facility radiological surveys were conducted in preparation for defueling, and reactor disassembly. No surface contamination in excess of twice background has been identified on facility equipment removed or disposed, building surfaces, reactor external surfaces, or on laboratory equipment and furniture. In addition, surveys were conducted in the only floor drain in the reactor site (in the reactor room to capture potential leakage of radiologically uncontaminated chromated water), in the floor electrical penetrations opened to verify status, and on piping penetrations through the walls and floor of the facility used to provide utility services (e.g., gas, compressed air, and water). Two small glass drain lines from laboratory sinks were surveyed and removed with no detectable contamination in or on the glass surfaces or in the associated traps.
No contamination in excess of twice background was detected in any of these areas.
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Particularly noteworthy is contamination survey data from reactor internals obtained during reactor defueling. All surfaces monitored were <<100 dpm/100 cm2, and <<1,000 dpm/100 cm2. These surfaces included the graphite reflectors that were in direct contact with the polyethylene fuel plates, the core tank internal surfaces, control rod drive guide thimbles, and the glory hole tube.
Volumetric samples were collected and analyzed, as follows:
Four concrete cores from reactor pedestal shield blocks at maximally-exposed surfaces.
Four concrete cores: two obtained from the concrete reactor pedestal and two from the floor under it.
Three concrete cores from the building wall that was cut out to facilitate removal of the reactor tank (including samples collected in line with the reactor glory hole).
One aqueous liquid sample from the reactor shield tank (chromated water).
One aqueous liquid sample from the sink trap in room 61B.
The samples were submitted to General Engineering Laboratories (Charleston, South Carolina) for analysis. No activation product activity was detected in the concrete samples when analyzed by gamma spectroscopy. Aliquots from all liquid samples were also analyzed by liquid scintillation counting for tritium and 14C, with no activity detected.The sampling data supports the initial assessment that any activation of the building structure is negligible. Data are presented in the FSS Plan, Revision 1 (Enclosure 2).
Removal of all reactor components has been completed and the rooms in Zachry Engineering Center emptied in preparation for the FSS work. The tile floors, identified by the renovation contractor as potentially asbestos-bearing material, were confirmed to meet surface contamination limits and asbestos abatement work was completed. The exposed concrete floor has been surveyed and determined to be free of detectable surface contamination, allowing preparations for Final Survey Status work to continue. An additional survey of the floors will be conducted as part of the Final Survey Status.
Data evaluation will be performed on Final Survey Status results for individual survey units to determine whether the survey unit meets the release criteria. Static and scan surveys must individually pass the 60Co screening value release criteria (and the TAMU requirement that no survey point exceed twice background) for the survey unit to pass. Instrument count rates are necessarily the measurements of record and will be recorded as such. No statistical tests are required. Sample data will be summarized and presented in the final survey report.
5.9 Survey Instruments Based on guidance from the referenced NUREG documents (Section 2.0), TAMU has selected instrumentation that provides the accuracy and reliability required for the surveys to be undertaken accurately and thoroughly. Given the relatively low instrument background count rates and high counting efficiencies, 100 cm2 dual phosphor detectors (Ludlum Instruments Model 43-
- 93) have been used with dual channel scaler/ratemeters (Ludlum Instruments Model 2360) for radiological surveys conducted in support of defueling and cleanup work. These were augmented with thin-window pancake Geiger-Mueller detectors with scaler/ratemeters (Ludlum Instruments Model 43-9 detectors with Model 3 scaler/ratemeters) to access smaller diameter penetrations (e.g., for electric cables, water supply lines, natural gas lines, and the drain piping).
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For direct comparison with proposed confirmatory surveys, the Final Survey Status Plan for contamination is being implemented using large area gas proportional detectors (Ludlum Instruments, handheld 126 cm2 model 43-68, and a cart-mounted 580 cm2 model 43-37 floor monitor). These detectors have been extensively evaluated and the data published in a variety of documents, including Decommissioning Health Physics (Ablequist, 2001), and NUREG-1507.
Operational surveys include swipes for removable contamination. Swipes are counted using a dual channel scaler (Ludlum Instruments 2929 with a 43-10 dual phosphor detector).
5.10 Release Criteria Since no detectable contamination has been identified in the facility or on associated equipment, no specific radionuclides of concern have been identified. Cobalt-60 (60Co) has been conservatively selected as the possible radionuclide of concern, and its corresponding screening value for surface contamination, as presented in NUREG 1757 (Table H.1 of volume 2), is the applicable regulatory limit for the project.
The TAMU requirements for unrestricted release are specified in the Radiological Safety Program, Section 7, paragraph B, Limits, paragraph 2.
Contamination levels on laboratory surfaces (removable) as determined by either wipe survey or instrument survey:
- a. no detectable contamination above background, i.e., not more than twice background levels
- b. the determination of no detectable contamination above background must be made with a detector which has been response checked within the past 12 months and which is suitable for measuring the type(s) of radiation expected.
Although specifically noted as applicable to removable surface contamination, it is also being applied to directly measured total contamination (i.e., fixed + removable). These criteria for removable and total contamination are well within the screening values presented in Appendix H to NUREG-1757 for typically encountered radionuclides (including 60Co, the limiting value in the table H.1) as well as current State of Texas limits that remain applicable to State-licensed activities at TAMU.
5.11 Protection of Workers and the Public Industrial safety specialists, such as experienced health physics staff, professional staff, along with management personnel, will be responsible for ensuring that the project complies with applicable federal safety requirements and general safe work practices.
All personnel working on the project have received appropriate training to recognize and understand potential hazards and risks. Training requirements for subcontractors will be determined based on the specific task the subcontractor is performing.
The Project Coordinator or his/her designee (through the TAMU EHS personnel) will direct site activities necessary for ensuring that the project meets occupational safety and health requirements for protection of project personnel and the public. The functional responsibility will be to ensure compliance with the Occupational Safety and Health Act of 1973.
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As a minimum, the management on-site shall implement the following:
General site safety procedures A requirement for a daily site safety meeting TAMU emergency contact telephone numbers Local emergency medical responders (as required) 5.12 Data Collection Quality Assurance Measurements will be performed in accordance with the Final Survey Status Plan by qualified personnel following written instrument operating procedures. Instrument calibration practices meet ANSI standards and daily background and source response checks of instruments will be performed. For quality control purposes, static and removable activity measurements will be obtained at 2 locations in each survey unit.
5.13 Security Plan and Emergency Plan The AGN-201M SNM, reactor and associated components have been removed from the Zachry Engineering Center. TAMU will follow 10 CFR 50.54(p) for changes to the Security Plan. TAMU is modifying the Security Plan, as appropriate, during the removal of the AGN-201M reactor and associated components, and the decontamination of the Zachry Engineering Center. TAMU will continue to monitor and restrict access to Zachry Engineering Center until it achieves unrestricted release. TAMU has no intention of reducing the safeguard effectiveness for the AGN-201M Security Plan for the Zachry Engineering Center until the unrestricted release is approved by the NRC.
Once the FSS results have been shown to meet 10 CFR 20.1401 criteria for unrestricted release for the Zachry Engineering Center, the material possession will be less than regulatory requirement for having a Physical Security Plan (Category 3). Therefore, TAMU is requesting to eliminate the AGN-201M Physical Security Plan.
The AGN-201M fuel, SNM, reactor and associated components have been removed from the Zachry Engineering Center. TAMU will follow 10 CFR 50.54(q)(iv)(3) in evaluating changes to the current AGN-201M Emergency Plan. TAMU will maintain all records of the proposed changes in accordance with 10 CFR 50.54(q)(iv)(5). Residual radioactivity levels, if any, remaining in Zachry Engineering Center do not approach the emergency planning thresholds of 10 CFR 30.72, Schedule C. Therefore, TAMU is requesting to eliminate the AGN-201M Emergency Plan.
5.14 Schedule The following are proposed milestones to achieve the unrestricted release of the Zachry Engineering Center:
Reactor and Associated Components Removed and Transported to the NSC (Complete);
Cleanup and Decontamination (if needed) of the Zachry Engineering Center (Complete);
Final Survey Results Completed (11/18/2016);
Submit Survey Results to U.S. NRC (12/09/2016);
U.S. NRC Completes Inspection of the Zachry Engineering Center (12/16/2016); and U.S. NRC Issues Unrestricted Release Amendment (12/30/2016).
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5.15 FSS Plan Changes Any changes to the Final Survey Status Plan will be conducted in accordance with 10 CFR 50.59.
5.16 Conclusion The AGN-201M SNM, reactor, and associated components have been relocated to the NSC facility for temporary storage. TAMU will comply with 10 CFR 20.1402 criteria for unrestricted release of the Zachry Engineering Center.
In the future, the AGN-201M reactor will be reconstructed and ultimately brought back to an operational status. This project is taking all steps deemed necessary to retain the integrity of this reactor and associated components. While the AGN-201M reactor and associated components are stored at the NSC facility the AGN-201M license and applicable TSs will remain active.
Once the FSS results have been shown to meet 10 CFR 20.1401 criteria for unrestricted release for the Zachry Engineering Center, the NRC regulatory requirements for the Emergency Plan and the Physical Security Plan no longer exist for the AGN-201M reactor. Therefore, reference to the plans can be eliminated from the AGN-201M License and TSs.
Technical Specification Sections 5.2 and 5.3 contain terminology specifically identifying Fuel Storage and the Zachry Engineering Center. Now that the successful removal of the reactor and associated components has occurred, the TSs are no longer applicable as the building will be empty. Thus, these TSs can be eliminated.
Following the comprehensive surveys as described in the FSS plan, TAMU will provide the U.S.
NRC with the results of the surveys to justify the unrestricted release the Zachry Engineering Center. The survey results are intended to demonstrate that areas of the Zachry Engineering Center that previously housed the AGN-201M reactor satisfy the unrestricted release criteria of the U.S. NRC. The Zachry Engineering Center can then be reused without radiological restrictions.
TAMU has concluded, based on the considerations above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by the proposed activities, (2) there is reasonable assurance that such activities will be conducted in compliance with U.S. NRC regulations, and (3) the issuance of this amendment will not be inimical to the common defense and security or the health and safety of the public.
6.0 CHANGES TO THE AGN-201M LICENSE AND TECHNICAL SPECIFICATIONS Once the FSS results have been shown to meet 10 CFR 20.1401 criteria for unrestricted release for the Zachry Engineering Center, the NRC regulatory requirements for the AGN-201M Emergency Plan and Physical Security Plan no longer exist for the AGN-201M reactor. Therefore, reference to the plans can be eliminated from the AGN-201M License and TSs. Specifically, references to the plans on page 3 of the AGN-201M license and TSs 6.4.3(c) and TS 6.6(f)are being eliminated.
Technical Specification Sections 5.2 and 5.3 are also being eliminated as the AGN-201M SNM, reactor, and associated components have been disassembled, transported, and placed into storage at the NSC facility for a period up to five years. These TSs specify the fuel storage location
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and various rooms within Zachry Engineering Center. Once unrestricted release is achieved, the AGN-201M site will be turned over for complete renovation and the former Zachry Engineering Center will no longer exist; the building is being completely renovated and transformed into the Zachry Engineering Education Complex. Therefore, deleting TSs 5.2 and 5.3 is warranted.
to Enclosure 1 contains proposed TSs and license page changes.
7.0 ENVIRONMENTAL CONSIDERATION
7.1 Proposed Action:
Issuance of the proposed LAR for the AGN-201M reactor (Facility License No. R-23, Docket No.
50-59) for the unrestricted release of the Zachry Engineering Center.
Following the relocation and storage of the AGN-201M SNM, reactor and associated components to the NSC facility, the Zachry Engineering Center is ready for final surveys and any decontamination (as necessary). This LAR proposes that the U.S. NRC approve the unrestricted release of the Zachry Engineering Center and deletion of TS Sections 5.2 and 5.3.
7.2 Environmental Impacts of the Proposed Action Surveys over the operating history of the AGN-201M reactor indicate very little, if any, contamination in the Zachry Engineering Center. The procedures used will control radiation exposure to the workers, public, and environment. TAMU will follow the FSS plan to support the unrestricted release of the Zachry Engineering Center. This LAR will be supplemented with the final radiological survey results, once they have been completed. TAMU anticipates submitting the survey results in December 2016. Implementation of the FSS plan will demonstrate compliance with U.S. NRC regulations and guidance in support of the unrestricted release of the Zachry Engineering Center.
Texas A&M University will comply with the requirements of 10 CFR 20.1402 radiological criteria for the unrestricted release of the Zachry Engineering Center. In accordance with this rule, the Zachry Engineering Center will be considered acceptable for unrestricted release if the residual radioactivity that is distinguishable from background radiation results in a TEDE to an average member of the critical group does not exceed 25 mrem (0.25 mSv) per year.
The FSS plan requires that the release surveys demonstrate that the former AGN-201M site within the Zachry Engineering Center has been certified clean and satisfies unrestricted release criteria for 1) the U.S. NRC, 2) the state of Texas Department of State Health Services, and 3) Texas A&M University Radiological Safety, Environmental Health and Safety. If these criteria are satisfied, then the remaining structure can be reused without radiological restrictions.
7.3 Environmental Impacts of the Alternatives to the Proposed Action As an alternative to the proposed unrestricted release of the subject area within the Zachry Engineering Center, the potentially-contaminated site would remain in possession-only status under Facility Operation License No. R-23. It would also eventually be subject to the U.S. NRC rule Timeliness in Decommissioning of Material Facilities (59 FR 36026-36040). This would eliminate the benefits of incorporating the subject area into the ongoing expansion of the Zachry Engineering Center for increasing the engineering education activities at TAMU.
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7.4 Finding of No Significant Impact Based on the above, TAMU finds that issuing the proposed LAR for the unrestricted release of the Zachry Engineering Center and the modifications to TS Section 5.2 and 5.3 will have no significant impact on the environment. TAMU is committed to following U.S. NRC rules and regulations to achieve the unrestricted release of the Zachry Engineering Center. The implementation of the FSS plan will demonstrate compliance with U.S. NRC regulations and guidance in support of the unrestricted release of the Zachry Engineering Center. Therefore, TAMU finds that issuing the proposed LAR will have no significant environmental impacts.
8.0 NO SIGNIFICANT HAZARDS CONSIDERATION The LAR will allow TAMU to delete TS Sections 5.2 and 5.3 associated with fuel storage and the term Zachry Engineering Center as well as justify the unrestricted release of the Zachry Engineering Center. Discussion of the expansion of Zachry Engineering Center has been presented to the U.S. NRC in several correspondences from TAMU. The guidance was followed to achieve the goal of unrestricted release, as allowed by 10 CFR 20.1401. The FSS plan will be followed to ensure the Zachry Engineering Center attains unrestricted release in accordance with the U.S. NRC regulations.
The AGN-201M SNM, reactor, and associated components have been removed from the Zachry Engineering Center. All potential hazards related to the previously-installed reactor have been eliminated. TAMU has evaluated the potential for significant hazards associated with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, as presented below:
- 1. Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?
Response: No.
The transport of the AGN-201M SNM, reactor, and associated support equipment renders the area within the Zachry Engineering Center empty. Once empty and the FSS results have been shown to meet 10 CFR 20.1401 criteria for unrestricted release for the Zachry Engineering Center, the NRC regulatory requirements for the Emergency Plan and Physical Security Plan no longer exist for the AGN-201M reactor. Therefore, reference to the plans can be eliminated from the AGN-201M License and TSs. In addition, TS Sections 5.2 and 5.3 are no longer applicable and can be deleted from the AGN-201M TSs. The empty room, following comprehensive cleaning and surveys, will meet the criteria to be released for unrestricted use. Therefore, this TS change and compliance with the governing rules and regulations fulfills the goals and objectives required to support unrestricted release of the Zachry Engineering Center. The proposed changes do not involve a significant increase in the probability or consequences of an accident previously evaluated. The Technical Evaluation describes the methodology and requirements TAMU intends to meet to achieve unrestricted release of the Zachry Engineering Center.
- 2. Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?
Response: No.
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The AGN-201M SNM, reactor, and associated components have been transported to and are now stored at the TEES NSC. Once empty and the FSS results have been shown to meet 10 CFR 20.1401 criteria for unrestricted release for the Zachry Engineering Center the NRC regulatory requirements for the Emergency Plan and Physical Security Plan no longer exist for the AGN-201M reactor. Therefore, reference to the plans can be eliminated from the AGN-201M License and TSs. In addition, TS Sections 5.2 and 5.3 are no longer requiredsince the surveillance would be applied to empty rooms. As such, it is not credible to postulate the possibility of a new or different kind of accident from any accident previously evaluated. The AGN-201M reactor license and applicable TSs will remain in effect while the AGN-201M SNM, reactor, and associated components are stored at the NSC, thus eliminating any association with the Zachry Engineering Center. There are no new accidents or unevaluated scenarios associated with preparing the Zachry Engineering Center for unrestricted release.
- 3.
Does the proposed amendment involve a significant reduction in a margin of safety?
Response: No.
There are no activities to be undertaken associated with the AGN-201M, as all work is to be performed in the empty Zachry Engineering Center. Noting the work to be performed, the existing margin of safety is greatly enhanced relative to conditions at the start of the project, when all the AGN-201M equipment was in the building. Removal of all equipment demonstrates that there will be no reduction in the margin of safety and no adverse consequences to the staff and surrounding areas.
9.0 CONCLUSION
The AGN-201M SNM, reactor, and associated components have been relocated to the TEES NSC for temporary storage. TAMU will comply with 10 CFR 20.1402 criteria for unrestricted release of the Zachry Engineering Center.
The FSS plan will be implemented to provide the basis for the unrestricted release of the Zachry Engineering Center. This project is taking all steps deemed necessary to retain the integrity of this reactor and associated components while stored at the NSC facility. While the AGN-210M reactor and associated components are stored at the NSC facility the AGN-201M license and applicable TSs will remain active.
Once the FSS results have been shown to meet 10 CFR 20.1401 criteria for unrestricted release for the Zachry Engineering Center, the NRC regulatory requirements for the Emergency Plan and Physical Security Plan no longer exist for the AGN-201M reactor. Therefore, reference to plans can be eliminated from the AGN-201M License and TSs.
Technical Specification Sections 5.2 and 5.3 contain terminology specifically identifying Fuel Storage and the Zachry Engineering Center. Having successfully removed the AGN-201M SNM, reactor, and associated components from the Zachry Engineering Center, these TSs can be deleted.
Texas A&M University will provide the U.S. NRC with the results of the FSS to justify the unrestricted release the Zachry Engineering Center. The survey results are intended to demonstrate that areas of the Zachry Engineering Center that previously housed the AGN-201M reactor satisfy the unrestricted release criteria of the U.S. NRC. The Zachry Engineering Center can then be reused without radiological restrictions.
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TAMU has concluded, based on the considerations above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by the proposed activities, (2) there is reasonable assurance that such activities will be conducted in compliance with the U.S. NRC regulations, and (3) the issuance of this amendment will not be inimical to the common defense and security or the health and safety of the public.
ATTACHMENT 1 TEXAS A&M UNIVERSITY FACILITY LICENSE R-23, DOCKET NO. 50-59 AMENDED FACILITY OPERATING LICENSE AGN-201M REACTOR PROPOSED PAGES:
TECHNICAL SPECIFICATION PAGES 15, 20, and 21 FACILITY LICENSE NO. R-23 PAGE 3
- c. The core, reflector, and lead shielding are enclosed in and supported by a fluid-tight steel reactor tank. An upper or "thermal column tank" may serve as a shield tank when filled with water or a thermal column when filled with graphite.
- d. The 6 1/2 foot diameter, fluid-tight shield tank is filled with water constituting a 55 cm thick fast neutron shield. The fast neutron shield is formed by filling the tank with approximately 1000 gallons of water. The complete reactor shield shall limit doses to personnel in unrestricted areas to levels less than permitted by 10 CFR 20 under operating conditions.
- e. Two safety rods and one control rod (identical in size) contain less than 15 grams of U-235 each in the same form as the core material. These rods are lifted into the core by electromagnets, driven by reversible DC motors through lead screw assemblies.
De-energizing the magnets causes a spring-driven, gravity-assisted scram. The fourth rod or fine control rod (approximately one-half the diameter of the other rods) is driven directly by a lead screw. This rod may contain fueled or unfueled polyethylene.
5.2 Fuel Storage DELETED 5.3 Reactor Room, Reactor Control Room, Accelerator Room DELETED 6.0 ADMINISTRATIVE CONTROLS 6.1 Organization The administrative organization for control of the reactor facility and its operation shall be as set forth in Figure 1 attached hereto. The authorities and responsibilities set forth below are designed to comply with the intent and requirements for administrative controls of the reactor facility as set forth by the Nuclear Regulatory Commission.
15
- c. Proposed tests or experiments which are significantly different from previous approved tests or experiments, or those that involve an unreviewed safety question as defined in 10 CFR 50 paragraph 50.59.
- d. Proposed changes in Technical Specifications or licenses.
- e. Violations of applicable statues, codes, regulations, orders, Technical Specifications, license requirements, or of internal procedures or instructions having nuclear safety significance.
- f.
Significant operating abnormalities or deviations from normal and expected performance of facility equipment that affect nuclear safety.
- g. Reportable occurrences.
- h. Audit reports.
6.4.3 Audits Audits of facility activities shall be performed at least quarterly under the cognizance of the Reactor Safety Board but in no case by the personnel responsible for the item audited. These audits shall examine the operating records and encompass but shall not be limited to the following:
- a. The conformance of the facility operation to the Technical Specifications and applicable license conditions, at least annually.
- b.
DELETED
- c.
DELETED 6.4.4 Authority The Reactor Safety Board shall report to the President and shall advise the Head of the Department of Nuclear Engineering on those areas of responsibility outlined in section 6.1.6 of these Technical Specifications.
6.4.5 Minutes of the Reactor Safety Board The Chairman of the Reactor Safety Board shall direct the preparation, maintenance, and distribution of minutes of its activities. These minutes shall include a summary of all meetings, actions taken, audits, and reviews.
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6.5 Approvals The procedure for obtaining approval for any change, modification, or procedure which requires approval of the Reactor Safety Board shall be as follows:
- a. The Reactor Supervisor shall prepare the proposal for review and approval by the Head of the Department of Nuclear Engineering.
- b. The Head of the Department of Nuclear Engineering shall submit the proposal to the Chairman of the Reactor Safety Board.
- c. The Chairman of the Reactor Safety Board shall submit the proposal to the Reactor Safety Board members for review and comment.
- d. The Reactor Safety Board can approve the proposal by majority vote.
6.6 Procedures There shall be written procedures that cover the following activities:
- a. Startup, operation, and shutdown of the reactor.
- b. Fuel movement and changes to the core and experiments that could affect reactivity.
- c. Conduct of irradiation and experiments that could affect the operation or safety of the reactor.
- d. Preventative or corrective maintenance which could affect the safety of the reactor.
- e. Surveillance, testing, and calibration of instruments, components, and systems as specified in section 4.0 of these Technical Specifications.
- f.
DELETED The above listed procedures shall be approved by the Head of the Department of Nuclear Engineering and the Reactor Safety Board. Temporary procedures which do not change the intent of previously approved procedures and which do not involve any unreviewed safety question may be employed on approval by the Reactor Supervisor.
6.7 Experiments
- a. Prior to initiating any new reactor experiment and experiment procedures shall be prepared by the Reactor Supervisor and reviewed and approved by the Head of the Department of Nuclear Engineering and the Reactor Safety Board
- b. Approved experiments shall only be performed under the cognizance of the Head of the Department of Nuclear Engineering and the Reactor Supervisor.
21
- 2)
Technical Specifications The Technical Specifications contained in Appendix A, as revised through Amendment xx, are hereby incorporated in their entirety in the license. The licensee shall operate the facility in accordance with the Technical Specifications.
(3)
Physical Security Plan DELETED D.
DELETED E.
This license is effective as of the date of issuance and shall expire at midnight, August 26, 1997.
FOR THE NUCLEAR REGULATORY COMMISSION
/RA/
Brian K. Grimes, Assistant Director For Engineering & Projects Division of Operating Reactors
Attachment:
Appendix A, Technical Specifications dated Date of Issuance: April 25, 1979 Amendment xx
ENCLOSURE 2 TEXAS A&M UNIVERSITY FACILITY LICENSE R-23, DOCKET NO. 50-59 AMENDED FACILITY OPERATING LICENSE AGN-201M REACTOR FINAL STATUS SURVEY PLAN, REVISION 1
SURVEYPLANFORTHE UNRESTRICTEDRADIOLOGICALRELEASEOFTHE AGN201MRESEARCHREACTORFACILITY ZACHRYENGINEERINGCENTER TEXASA&MUNIVERSITY COLLEGESTATION,TEXAS
Revision1 November10,2016
Contents ACRONYMS,ABBREVIATIONS,ANDUNITS...........................................................................................1
1.0 INTRODUCTION
.......................................................................................................................2 2.0 PURPOSEANDSCOPE.............................................................................................................3 3.0 SITEDESCRIPTION...................................................................................................................3 4.0 RADIONUCLIDECONTAMINANTSANDCRITERIA...................................................................9 5.0 IMPACTEDAREASANDSURVEYUNITS................................................................................13 6.0 SURVEYAPPROACH.......................................................................................................................14 6.1 General...........................................................................................................................14 6.2 SitePreparation.................................................................................................................15 6.3 IntegratedSurveyStrategy...............................................................................................15 6.4 FSSSurveyInstrumentation..............................................................................................17 6.5 SurfaceScans..................................................................................................................18 6.6 StaticSurfaceActivityMeasurements............................................................................19 6.7 RemovableContaminationMeasurements...................................................................19 6.8 SamplesandAnalyses....................................................................................................19 6.9 QualityAssurance/QualityControl...................................................................................19 7.0 DATAEVALUATION...............................................................................................................19 8.0 ISOLATIONANDCONTROL.20 9.0 REPORT20
10.0 REFERENCES
.......................................................................................................................20 APPENDIXA...................................................................................................................................A1 APPENDIXB...................................................................................................................................B1
1
ACRONYMS,ABBREVIATIONS,ANDUNITS
C carbon cm centimeter cm2 squarecentimeter cpm countsperminute Cs cesium dpm disintegrationsperminute Eu europium 3H tritium hr hour keV kiloelectronvolt m
meter m2 squaremeter MARSSIM MultiAgencyRadiationSurveyandSiteInvestigation Manual MDC minimumdetectableconcentration MDCR minimumdetectablecountrate MeV millionelectronvolts NRC NuclearRegulatoryCommission pCi picocurie pCi/g picocuriepergram PuBe plutoniumberyllium(neutronsource)
RSSI RadiationSiteSurveyandInvestigation TAMU TexasA&MUniversity TDSHS TexasDepartmentofStateHealthServices U
uranium Ci microcurie
2
UNRESTRICTEDRADIOLOGICALRELEASESURVEYPLAN AGN201MRESEARCHREACTORFACILITY ZACHRYENGINEERINGCENTER TEXASA&MUNIVERSITY,COLLEGESTATION,TX
1.0 INTRODUCTION
TexasA&MUniversity(TAMU)isrenovatingtheZachryEngineeringCenter.ThisCenterhoused the AGN201Mreactor,licensedbytheNuclearRegulatoryCommission(FacilityLicenseR23).Italso containedofficesandlaboratoriesinwhichradiologicalmaterialswereusedinsupportofreactor operationsandotheractivities,asauthorizedunderTexasDepartmentofStateHealthServices (TDSHS)licenseL00448.Furnishings,materialsandequipmentweresurveyedandremovedfrom theStatelicensed areasofthefacility.Buildingsurfacesinthosenonreactorareasweresurveyed and demonstratedtosatisfytheTAMUcriterionfordemolitionwithoutneedfor radiological restrictions.Theseareashavebeenrazedinpreparationforrenovation.
Thereactorandassociatedcomponentshavebeenpackagedandplacedinsecureoffsitestorage, awaitingreinstallationinanewfacility(notethatthePart50licenseisnotbeing terminated).
Remainingmaterialsandequipmentinthereactorfacilityhavebeen surveyed,removed,and dispositioned inaccordancewiththe TAMUcriteria. Radiological surveys performed over the operatinghistoryoftheAGN201MreactorhaveidentifiednocontaminationoverTAMUrelease limitsinthereactorareasofZachryEngineeringCenter.Inaddition,recentsurveysconducted duringreactordisassemblyandinsupportoftheremoval,packagingandtransportofthereactor fuelandSNMhavenotidentifiedcontaminationoverTAMUreleaselimitsonthereactorexternal surfacesoronreactorinternalcomponentsurfaces(e.g.,inthecoretank,oncontrolroddrive thimblesthatpassthroughtheuncladfueldisks,andonthelowercoreplate).
ReNukeServices,Inc.,ofOakRidge,TN,hasbeencontractedbyTAMUtoremoveandrelocatethe reactor,developasurveyplan,andconductunrestrictedreleasesurveysofthebuilding.Thefinal resultswillbesubmittedasasupplementtoalicenseamendmentrequestfortheunrestricted releaseoftheZachryEngineeringCenter.
Office furnishings, miscellaneous materials and nonreactor equipment have been surveyed in accordance with the TAMU Radiological Safety Program and removed from the facility. No contaminateditemswereidentified.Screeningsurveys ofthereactorfacilitysurfaceshavebeen performed,withnocontaminationdetectedandnoneedfordecontaminationidentified.Based upon reactor power history and neutron surveys during power operation, activation of the buildingstructureisconsideredveryunlikely.Concretesamplesfromshieldblocksaroundthe reactor support skirt and from walls in the reactor room have been analyzed by an offsite laboratory for the presence of neutron activation products, and support this assessment; no activation products were detected. Based upon these surveys, the AGN201M design
3
characteristics,andthefacilityhistoricaluses,theareashavebeenclassifiedastocontamination potential.Radiologicalsurveysoftheimpacted areaswillbeconductedtodemonstratethatthe facility conditions satisfy requirements for unrestricted future use and thus enable building renovationstoproceedwithoutradiologicalsafetyconstraints.
2.0 PURPOSEANDSCOPE
ThepurposeofthereleasesurveysistodemonstratethatareasoftheTexasA&MUniversity ZachryEngineeringCenter,whichhousestheAGN201Mreactorfacility,satisfycriteriaofthe Nuclear Regulatory Commission, Texas Department of State Health Services, and Texas A&M University Radiological Safety, Environmental Health and Safety for unrestricted release. By satisfyingthesecriteria,theremainingstructurecanbedemolishedorreusedwithoutradiological restrictions.
TexasA&MUniversitywillcomplywiththerequirementsof10CFR20.1402,radiologicalcriteria fortheunrestrictedreleaseoftheZachryEngineeringCenter.Inaccordancewiththisrule,thesite will be considered acceptable for unrestricted use if the residual radioactivity that is distinguishablefrombackgroundradiationresultsinatotaleffectivedoseequivalent(TEDE)toan averagememberofthepublicdoesnotexceed25mrem(0.25mSv)peryear.Nocontamination hasbeendetectedonanysurfacesorcomponentsduringextensivesurveysconductedinsupport ofdefuelingandduringearlierscopingsurveys,andTAMUcommitstousingthedefaultscreening valuesforsurfacecontaminationaspresentedinAppendixHtoNUREG1757,Volume2,Revision 1asupperlimitsfortheproject.Sitecharacteristicssupporttheuseofthesevalues,asonly superficial surface contamination is expected. There are no buried pipes or potentially contaminatedstructures,andnounusualradionuclidesareanticipated.Thescreeningvalueshave been determined by the NRC to be ALARA; no further pathways evaluations are required (AppendixNtoNUREG-1757,Volume2).TAMUsselfimposedreleasecriteriaaremorelimiting (contamination is not to exceed twice background, using appropriate instrumentation), as explainedbelow.
3.0 SITEDESCRIPTION
Figure1isasitemapoftheTexasA&Mcampus,indicatingthelocationoftheZachry Engineering Center,onBizzellStreetnearUniversityDrive. This Centerwashometo EngineeringStudent ServicesandAcademicProgramsOffice,aswellastheDepartmentof NuclearEngineeringandthe DepartmentofElectricalandComputerEngineering.Thebuilding isalargeconcretestructureand consistsofabasementlevel,agroundlevel,andthree additionalfloors. AsdepictedinFigure3, theAGN201MreactorwaslocatedinRoom61Bonthe groundfloor,inthesouthwestportionof thebuilding. Itisafullyselfcontainedunit,withno externalcoolantorirradiationsystems.The reactorcoreisarightcylinder,approximately26cmdiameterby24cmhighconsistingofninefuel discsandfueledcontrolrodscontainingnominally665gramsofU235atanenrichmentofjustless than20%.ThefuelisamixtureofUO2microspheresina polyethylenematrix. Thecoreandthe controlandsafetyrodsaresurroundedbyaleaktight, 95cmdiameterby148cmhighcoretank.
4
A10cmthickleadshieldsurroundsthecoretank and20cmthickgraphitereflectors. A198cm diameterby213cmheightwatershieldtanksurroundsthereactorcoreassembly(Figure2). The maximumauthorizedsteadystate operatingpowerlevelis5watts,thermal.Thereactorhasnot operated for several years. The design of the AGN201M reactor precludes the possibility of groundwaterorsoilcontamination,astherearenoexternalcoolantpumps,heatexchangers,or coolantmakeup/cleanupsystems,andnoexternalirradiationloops.Inaddition,thebasicdesign precludestheneedforradioactivewasteprocessingsystems(e.g.,nowastecompaction,liquid waste treatment, or contaminated off gas treatment systems). Accordingly, the FSS does not addresssoilorgroundwatersampling.
Room60Cwasprimarilyusedforofficespaceandaccesscontrol.Room61Awasusedinsupport of reactor operations (e.g., safeguards laboratory work, experiment preparation). Room 61B contains the reactor control console and a small inner room where radioactive sources were stored.AccesstothetopofthereactoristhroughRoom135onthe1stfloorlevel,directlyabove thereactorroom.Rooms60C,61A,61B,and135(whichalsopreviouslycontainedanionimplant particleaccelerator)constitutetheprimarysitesecurityboundariesforthereactor.Theserooms occupy approximately 170 m2 on each level. They have 1m reinforced concrete walls; the acceleratorroomceilingisalso1mthickconcreteandasteelplateliner.Figures3and4showthe layoutsofthereactorfacility;boldedoutlinesindicatePrimaryReactorSiteboundaries.
ApolyethylenetankwaslocatedintheBasementdirectlybeneaththeprimaryreactorfacilityand wasconnectedtoafloordraininRoom61Btoallowcollectionofwaterintheunlikelyeventof leakage from the reactor shield tank (radiologically uncontaminated chromated water). This capabilitywasnotused,andthetankremainedemptyuntilitssurveyandremoval.ThesinglePVC drainlinedidnotcontaindetectableradioactivitywhenexaminedduringscopingsurveys.Itwas removedandallsectionssurveyed,alongwiththepolyethylenetank.Rooms135and61Awere alsoequippedwithsinkdrainspreviouslyconnectedtoasumpintheStatelicensedareaofthe building.Nocontaminationwasdetectedintheglassdrainlineortheinlinetrapinthereactor areas,andnocontaminationwasidentifiedduringsamplingofthesumportheStatelicensed laboratorydrains.Thesedrainswereterminatedandthesumpreleasedaspartofthelaboratory decommissioning.
ThefacilityshareselectricpowerandairsupplywiththeremainderofZachryEngineeringCenter building. During normal power operation, ventilation for the reactor area was provided by a ventilationfaninRoom135,which pulledairthroughagratedopeningintheRoom61Bceiling.
Portionsoftheventilationsystem weresurveyedinearly2016duringlaboratoryfacilitysurveys, andfoundtomeetthe applicablereleasecriteria.
5
Figure1-MapofTexasA&MCampus,indicatinglocationofZachryEngineering
6
Figure2-CutawayViewofAGN201MReactor
7
Figure2a-AGN201MReactorwithoutblockshielding,ascurrentlylocatedinZachry EngineeringCenter
8
Figure3ReactorFacilityGroundFloor;BoldedoutlineindicatesSecurityBoundary
Figure4-ReactorFacilityFirstFloor;BoldedoutlineindicatesprimaryReactorSite Boundary
Sampled block wall
48 ---------------------------
27 -------------
27 ------------
48 --------------------
9
4.0 RADIONUCLIDECONTAMINANTSANDCRITERIA
AGN201MreactoroperationsintheZachryEngineeringCenterbeganin1972andconcludedin 2014. Duringtheschoolyearsof1999/2000through2009/2010,thereactorwasnotoperated.
Inotheryears,annualoperatingwatthoursrangedfrom4.32to82.36. Sincethe2009/2010 schoolyear,thetotaloperatingtimehasbeenapproximately138watthours.Therehasbeenno reactoroperationsince2014.RecordsandanecdotalinformationfromthepreviousSeniorReactor Operatorhave not revealedanyreactorincidentsoroccurrenceswhichmayhaveresultedin contaminationof surfacesexternaltothereactorshieldtank. Resultsofsurveysperformedby theTAMURadiologicalSafetystaffdidnotidentifyanydetectableremovablecontaminationon reactorcomponentsorreactor roomsurfaces.Recentscopingsurveysdidnotdetectanyfixed orremovablecontaminationonsurfacesinrooms61Aand61B. Consideringthelowpowerlevel andlimitedoperatingtime,low neutronfluencerate(1.5x108n/cm2sec,averageatthe5watts maximum licensed power), inherent shielding provided by the reactor components and containmenttank,andthedecaytimesince lastoperation,thelikelihoodofdetectableactivity infacilitystructuralmediaisconsideredtobenegligible.
Conservative,boundingcalculationsestimate152Eu(likelythepredominantactivationproductin concrete)specificactivityintherangeof103pCi/ginconcreteshieldblocksthatwerelocated around the reactor support skirt. Sampling and analyses was conducted to validate the calculationbased conclusion that no activation products are present at detectable levels.
Candidate radionuclides for concrete activation include 152Eu, 154Eu, 60Co, 134Cs, 3H, and 14C.
Laboratoryanalyses(gammaspectrometryandliquidscintillationcounting)ofcoresamplesare summarizedbelow.Samplesincludedcoresfrom4innermostshieldblockspreviouslyaroundthe reactorskirt(shieldingsubjecttothehighestneutrondose),1corefromtheNorthroomwall, collecteddirectlyacrossfromthegloryhole,3coresfromtheSouthblockwallinlinewiththe gloryhole,2coresfromthenominal31/2concretereactorpad,2coresfromtheconcretefloor directlyunderthereactorpad,and1corefromthewallintheaccesshallway,anareawithno significantneutronexposure.Noneofthesampleswerefoundtocontaindetectableactivation products,withminimumdetectableconcentrationsfortheradionuclidesofinterestlessthan10%
oftheNUREG1757soilscreeningvalues.EuropiumMDCswerealso<10%oftheEPAvaluesfor residentialsoils.ThesescreeningvaluesaredirectlyapplicableasaportionoftheSouthwallwas openedforremovalofthereactorshieldtank.Exposureratesurveys1meteroverthereactorpad werenotdifferentthanthenominal5microR/hambientexposureratesthroughoutthefacility.
SampleresultsarepresentedinTable1.
10
Table1.
Volumetricsampledata
134Cs 60C 152Eu 154Eu 3H 14C Noactivationproductsdetected MDC, pCi/g MDC, pCi/g MDC, pCi/g MDC, pCi/g MDC, pCi/g MDC, pCi/g Wall:hallway(noneutronirradiation) 5.82E02 7.23E02 1.12E01 1.73E01 5.43E+00 1.41E+00 Wall:Nside,oppositegloryhole 8.97E02 9.91E02 1.90E01 2.97E01 5.44E+00 1.37E+00 S.Wall1:IW1(wallremoved) 4.77E02 4.30E02 1.09E01 1.01E01 7.63E+00 6.26E01 S.Wall2:IW2(wallremoved) 4.52E02 4.11E02 1.40E01 1.30E01 7.85E+00 6.01E02 S.Wall3:IW3(wallremoved) 7.01E02 6.72E02 1.29E01 2.26E01 8.08E+00 6.21E01 Reactorshieldblock:E1 7.87E02 7.69E02 1.31E01 2.17E01 7.96E+00 5.98E01 Reactorshieldblock:S1 8.06E02 7.64E02 1.70E01 1.86E01 8.07E+00 6.14E01 Reactorshieldblock:N1 5.54E02 7.87E02 1.64E01 1.99E01 7.88E+00 6.07E01 Reactorshieldblock:W1 6.01E02 5.80E02 1.30E01 1.84E01 8.06E+00 1.00E+00 Reactorpadconcrete1 5.89E02 5.19E02 1.26E01 1.55E01 6.85E+00 6.34E01 Reactorpadconcrete2 5.59E02 5.20E02 1.14E01 1.41E01 6.30E+00 6.35E01 Floorunderreactorpad,1 9.17E02 6.72E02 1.77E01 2.07E01 6.27E+00 6.51E01 Floorunderreactorpad,2 6.87E02 5.17E02 1.69E01 1.98E01 6.58E+00 6.30E01
SouthWall(IW1toIW3)
ShieldBlockWall(4Samples)
ReactorPadConcrete(4samples)
Coveringshavenotbeen appliedoveranyknownlocationofcontamination. Thelocationinthe facilityconsideredmost likelytohavebeenimpactedbyreactoroperationsistheconcretefloor directlybeneaththe reactorshieldtank. Potentialactivationradionuclidesincludethe same radionuclidesintheabovetable.Thecoreassemblycontainsenricheduraniumfueland(likely) verysmallquantitiesof longerhalflifefissionproductsincluding 137Cs,90Sr,144Ce,and 95Zrand activation productssuchas60Coincomponents;however,thereisnohistoryofcontaminationby theseradionuclidesonsurfacesexternaltothereactor.
TheNRCreactorlicenseincludesa239PuBespecialformneutronsourcecontainingupto16grams of239Puforuseinreactoroperation.Thissourcewasleaktested(nocontaminationwasdetected),
removedfromtheAGN201Mreactor,andtransportedtooffsitestorage
Section 17.1.4 of NUREG1537 establishes the following criteria to release nonpower reactor facilitiesforunrestricteduse
11
- 1. a)nomorethan5microremperhourabovebackgroundat1meterfromthesurface measured for indoor gamma radiation fields from concrete, components, and structures,or
b)nomorethan10milliremperyearforgammaemittersabovebackgroundabsorbed dosetoanyperson,consideringreasonableoccupancyandproximity(NRCletters dated March17,1981andApril21,1982).
- 2. residualsurfacecontaminationconsistentwithRegulatoryGuide1.86.
Regulatory Guide 1.86 was withdrawn by NRC, effective August 12, 2016, although similarnumericalguidanceremainsinRegulatoryGuides8.21,HealthPhysicsSurveys forByproductMaterialatNRCLicensedProcessingandManufacturingPlants,and8.30, Health Physics Surveys in Uranium Recovery Facilities. The table of surface contaminationvalueshasbeenretained(seeTable2)fortheprojectasthesevaluesare alsoinTexasRegulation25TAC§289.202(ggg)(6),Acceptablesurfacecontamination levels(Ref2),andareapplicabletoStatelicensedactivitiesatTAMU.
Table2.
AcceptableSurfaceContaminationLevelsbasedonDetectability Nuclidea Total Removable Unat,U235,U238,andassociateddecay products 5000 dpm/100 cm2 1000dpm/100 cm2 Transuranics,Ra226,Ra228,Th230,Pa231,Ac227, I125,I129 100dpm/100cm2 20dpm/100cm2 Thnat,Th232,Sr90,Ra223,Ra224,U232,I126,I 131,I133 1000dpm/100cm2 200dpm/100cm2 Betagammaemitters(nuclideswithdecaymodes otherthanalphaemissionorspontaneousfission) exceptSr90andothersnotedabove 5000dpm/100cm2 1000dpm/100cm2 a.Wheresurfacecontaminationbybothalphaandbetagammaemittingradionuclidesexist,thelimits establishedforalphaandbetagammaemittingradionuclidesapplyindependently.
TheTAMUradiationsafetyprogramhasapolicyofnodetectableactivityfor unrestricteduse and release. No detectable activity is interpreted by TAMU as not exceeding twice the backgroundlevel(Ref1).
DuetootherZachryEngineeringCenterrenovationworkstartingpriortothereactorrelocation project,suitableconcretesurfacesoutsidethereactorcomplexwerenotavailableforreference backgroundmeasurements.BackgroundmeasurementswereperformedinaClass3area(Room 60C)onasectionofpouredconcretefloorunlikelytohavebeenimpactedbyreactoroperations.
Thisarea,aswiththeotherfloorareas,wascoveredwithfloortilesincethestartofreactor operations.Thetilehassincebeenremovedfromallareas.Thepouredconcretebackground levelsforthe126cm2gasflowproportionaldetectorsareeffectivelytheobservedambientbackground levels of 3 alpha cpm and 250 beta cpm. As expected, the larger (nominally 580 cm2) gasflow proportionalfloormonitorexhibitshigherambientbackgroundlevelsofapproximately9alphacpmand
12
300betacpm.Initialsurveyworksupportstheconservativeuseofambientbackgroundlevelsfor scanningsurveysofthefloorsandtheremainderofthefacilitysurfaces(primarilypouredconcrete walls,steelandglass).Theambientbackgroundvalueswillalsobeconservativelyappliedtosurveys oftwohigherdensityblockshieldwallsinRoom61B.Laboratoryanalysisdemonstratesahigher concentrationofthe232Thseriesradionuclidesrelativetootherblockandconcreteusedinfacility construction,andtheimpactonsurveysisanincreasedbackgroundcountrateof100cpmonthese blocks.Thismaterialspecificbackgroundwillnot,however,beapplied.Theambientbackground will also be used for scanning surveys of these walls. To summarize, no materialsspecific backgroundcountrateswillbesubtractedfromscanningsurveysoffacilitysurfaces.Notethat2 stepsurveyswillbeusedforstaticmeasurements,asdescribedinsection6.3,IntegratedSurvey Strategy.
The nominal ambient background values are used to calculate the sensitivity of the scanning surveys to ensure they are adequate relative to the surface contamination Screening Values presentedNUREG1757,AppendixH.Becausenoresidualradioactivityhasbeenidentifiedduring extensivesurveysofthereactor,associatedcomponents,andthefacility,nospecificradionuclides ofinteresthavebeenidentified.TheNUREG1757,AppendixHsurfacecontaminationscreening valuefor 60Co(7,100dpm/100cm2)hasbeenconservativelychosenforevaluationofpotential building contamination. Table 3 presents a summary of the minimum detectable surface contamination,theNRCscreeningvalue,andthesurfacecontaminationlevelscorrespondingto twicethebackgroundlevels(theTAMUconstraint).
Duringscanningsurveys,netcountratesexceeding450cpmbetawhenusingthe126cm2detectors, or800cpmbetaforthe580cm2 detector, willbeindicativeof contaminationexceedingthe screeningvaluefor60Co.
Theassumptionthattheremovableactivityfractiondoesnotexceed10%willbeevaluatedif contaminated areas are identified. Table 3 clearly demonstrates that meeting the TAMU Radiological Safety criteria for release will also satisfy the NRC requirements. As noted, no contamination has been detected and no specific radionuclides have been identified during extensivescopingsurveys; 60Cohasbeenconservativelyselectedasapossibleradionuclideof concern.Grossalphaandbetagammasurveyslimitswillbeapplied(i.e.,nottoexceedtwice background,alphaandbetagammaactivityevaluatedindependently).Alsonotethatnetcount ratesexceeding3cpmalphaor250cpmbetawhenusingthe126cm2detectors,or9cpmalphaor 300cpmbetaforthe580cm2detector,willbeindicativeof contaminationexceedingtheTAMU criteria(twicebackground)andwillrequirefurtherinvestigation.
13
Table3.
SummaryData Detector/Application MDA (dpm/100 cm2)
NRC Co-60 Default Screening Value (dpm/100 cm2)
TAMU twice background equivalent (net dpm/100 cm2) 126 cm2 gas proportional/scan Alpha - N/A
- 1500 beta Alpha - N/A*
7100 N/A 3000 126 cm2 gas proportional/static 63 alpha 470 beta Alpha - N/A*
7100 26 alpha (< MDC) 2200 beta 580 cm2 gas proportional/scan Alpha - N/A*
2280 beta (for a 100 cm2 spot)
Alpha - N/A*
7100 A > 2 x background reading will be investigated with a 126 cm2 detector Laboratory counter/removable activity 19 alpha 90 beta Alpha - N/A*
710 4 alpha 500 beta
- No potential alpha-emitting contaminants have been identified
MeasuredbackgroundexposurerateswithintheZachryEngineeringCenterare5to8microR/hr.
TheTAMUlessthantwicebackgroundcriterionwill bemetby confirmingthatdoseratesfrom backgroundplusresiduallicensedmaterialarenomorethan10microR/h,measuredat1meter frombuildingsurfaces.Thisisconsistentwiththepreviouslynoted guidancefromNUREG1537.
5.0 IMPACTEDAREASANDSURVEYUNITS
The MultiAgency Radiation Survey and Site Investigation Manual (MARSSIM) (Ref 3) defines impactedareasasthosewithapossibilityofresidualradioactivityinexcessofbackground levels.
Radiologicalsurveysofimpactedareasarerequiredtodemonstratethatestablished criteriahave been satisfied. Nonimpacted areas are those with no reasonable expectation of residual contamination;nosurveysofnonimpactedareasare required. Impactedareasareclassifiedas tocontaminationpotentialasfollows:
Class1: Areasthathave,orhadpriortoremediation,apotentialforradioactive contamination(basedonsiteoperatinghistory)orknowncontamination(basedon radiologicalsurveys)expectedtobeinexcessofestablishedunrestrictedrelease criteria.
Class2: Areasthathave,orhadpriortoremediation,apotentialforradioactive contaminationorknowncontamination,butarenotexpectedtoexceedestablished criteria.
Class3:Areasthatarepotentiallyimpactedbutarenotexpectedtocontain any residualradioactivity,orareexpectedtocontainlevelsofresidualactivityatasmall fraction oftheestablished criteria,basedonsiteoperatinghistoryandprevious radiologicalsurveys.
14
Therigorofareleasesurveyisbasedonthesecontaminationpotentialclassifications.Structure surveyunitsareestablishedwithsizelimitationspresentedinTable4.
Table4.
SurveyUnitAreabyClassification Classification MaximumArea(m2)
Class1 100 (floor surface)
Class2 100 to 1000 Class3 No limit
Table5containsapreliminarylistofAGN201Mreactorfacilityimpactedareasandsurvey units.
Thislistisbasedonusehistoryandpreviousmonitoringrecords.Screeningsurveys, conducted during removal of furnishings, materials, and equipment from the facility support the recommendedclassifications.
Table5.
ImpactedAreasandSurveyUnits
Class
Level
Room(s)
Surfaces
Numberof SurveyUnits
Class1
Ground
61A
Floorandlowerwalls
1
Ground
61B
Floorandlowerwalls
1
First
135
Floorandlowerwalls
2
Class2
Ground
61Aand61B
Upperwallsandceiling
1
Class2
First
135
Upperwallsandceiling
1
Class3
Ground
60C
All
1
6.0 SURVEYAPPROACH
6.1 General Thissurveyplanwaspreparedinaccordancewithguidelinesandrecommendations,presented in theMultiAgencyRadiationSurveyandSiteInvestigationManual. Theprocessdescribedin this reference emphasizes and incorporates the useof Data Quality Objectives and Data Quality Assessment,alongwithaqualityassurance/qualitycontrolprogram. Aqualityassuranceprogram forsurveyactivitieswillbeimplemented. Thegradedapproachis followedtoassurethatsurvey effortsaremaximizedinthoseareashavingthegreatest potentialforresidualcontaminationor thehighestpotentialforadverseimpactsofresidual contamination.
15
Trainedandqualifiedradiologicaltechnicianswillconductfieldmeasurements,followingstandard procedures and using calibrated instruments, sensitive to the potential contaminants.
Professionalhealthphysicspersonnelwillassessandevaluatethesurveydataandpreparea reportofthefindings.
6.2 SitePreparation Furnishings,materialsandequipmenthavebeenremovedfromthefacilityinaccordancewith TAMURadiationSafetyProgramprocedures.Followingremovalandtransferofthereactorand associated components, drains, ducts, diffusers, grates, cable trays, etc., were accessed and surveyed. Nominal100cm2dualphosphordetectors(LudlumInstrumentsModel4393)have been used with dual channel scaler/ratemeters (Ludlum Instruments Model 2360) for health physicssurveysconductedinsupportofdefuelingandcleanupwork.Notethatbackgroundand efficienciesforthesescintillationdetectorsareidenticaltothegasflowproportionaldetectors selectedforfinalstatussurveys.Useofthemodel4393scintillationdetectorswasaugmented with thinwindow pancake GeigerMueller detectors with scaler/ratemeters (Ludlum InstrumentsModel439detectorswithModel3scaler/ratemeters)toaccesssmallerdiameter penetrations(e.g.,usedforelectriccables,watersupplylines,naturalgaslines,etc).Todate,no buildingsurfaceshavebeenfoundtocontaindetectableresidual activity,withMDCswellbelow theNRCandTAMUreleasecriteriaaspresentedinTable2andnoremediationhasbeenrequired.
Buildingsurfaceshavebeenappropriately griddedtoprovideameansforreferencingsurvey locations. Measurementswillbeidentifiedbygridcoordinateor,ifnotpractical,byreferencingto buildingfeaturesorbyphotograph. Surfaceswherecontaminationwasdeemedlikely(Class1)or possible(Class2)havebeengriddedat1meter intervals,asispracticalfortheconditions. Grid originsareinthesouthwestcorneroftheroom. If,duringthesurvey, contaminationabovelimits isidentifiedinClass2orClass3areas,therigorofthesurveyunitwillbeincreased tothatofClass 1areas.
6.3 IntegratedSurveyStrategy
Radiologicalsurveyswillconsistof:
surfacescansforelevatedlevelsofgrossalpha,beta,andgammaradiationlevels, staticmeasurementsofgrossalphaandgrossbetaactivity, smearsforremovablegrossalphaandgrossbetaactivity,and samplingforlaboratoryanalysisofspecificradionuclidecontaminants,ifnetactivityis found
Baseduponfacilityhistoryandsurveysperformedinsupportofreactordisassemblyandremoval oftheshieldtank,therigorofsurveyswillfollowagradedapproachbasedonthelikelihoodof contamination. Table6indicatesthesurveyrigorforvariouscontaminationclassifications.
16
Table6.
SurveyRigorforEachSurveyUnit Contamination Class Alpha,Beta, andGamma Scan StaticAlphaandBeta Removable Alphaand Beta 1
100%all structure surfaces Systematic static measurement at a minimum of 18 locationsandatadditionallocationsofhighest potentialcontamination,basedonprofessional judgmentandscanresults Ateachstatic measurement location 2
50%floorand lowerwalls; 10%upperwalls andceiling surfaces Systematicstaticmeasurementataminimumof18 locationsandatadditionallocationsofhighest potentialcontamination,basedonprofessional judgmentandscanresults Ateachstatic measurement location 3
10%floor and1m2 aroundeach static measurement locationon lowerwalls Onefloormeasurementand1lowerwall measurementper10m2offloorareaineach room,andmeasurementsandatadditional locationsofpotentialcontamination,basedon professionaljudgmentandscanresults(minimum of18datapointspersurveyunit).
Ateachstatic measurement location
Becausetheacceptablereleasecriterionoftwicebackgroundislow,ScenarioB,as recommended byNUREG1505(Ref4),isthebasisforthesurveydesign.TheNullHypothesis forthatScenariois:
Thesurveyunitmeetsthereleasecriterion.
TheobjectiveofthereleasesurveyistoacceptthisNullHypotheses,bydemonstratingata TypeI
() decision error level of 0.05 and a Type II () decision error level of 0.025 that residual contaminationislessthantwicebackground. Therearemultiplebuildingsurfacetypes (concrete, metal,wood,glass,etc.)inmostsurveyunitsand,backgroundlevelswilllikelyvary, byinstrument, material,timeofday,andlocationwithinthefacility. Tofacilitateadjustingmeasurementsfor appropriatelocalizedbackgroundcontributions,apairedmeasurementapproach willbeused. To performpairedmeasurements,ameasurementisfirstperformedbyplacinga pieceofnominal1/4 inchplasticormetalshieldmaterial,betweenthesurfaceandtheLudlum4368detectorface. The static measurement is repeated without the intervening shield material, and the difference betweenthesecondandfirstmeasurementindicatesthenetcontaminationlevel.
Eachmeasurementwillbeindividuallyevaluatedandnoindividualmeasurementmay indicate detectableactivityinexcessoftheprojectlimits(e.g.,allnetmeasurementsmustbelessthanthe 3alphaand250 betacpmnominalcountratesasmeasuredwiththe4368detectorsthemore restrictiveTAMUlimits). Nostatisticaltestwillberequiredtodemonstratecompliance with releasecriteria.
Toestablishthenumberofmeasurementsneededtodemonstratethatresidualcontamination criteriahavebeensatisfied,aparameterknownastherelativeshift,whicheffectively describes thedistributionoffinalsampledata,iscalculated,asfollows:
17
(1) /=(DCGLLBGR)/
where:
/
= relativeshift DCGLCriteria= cleanupcriteria LBGR
= lowerboundofthegrayregionandisdefinedintheDQOsas50percent oftheDCGL. Wherefinalsampledataarenotyetavailable,MARSSIM guidance(Section5.5.2.2)assignsavalueofonehalfoftheDCGLforthe LBGR.
= standard deviation of the sample concentrations in the survey unit.
Where final sample data are not yet available, MARSSIM guidance (Section5.5.2.2)recommendsavalueof30percentoftheDCGL.
UsingtheequationforrelativeshiftandMARSSIMguidanceforsituationswherefinalsample data arenotyetavailable,therelativeshiftfordesignpurposesis(1-0.5)/0.3foravalueof1.67. Based ontherelativeshiftof1.67andTypeIandTypeIIdecisionerrorsof0.05and 0.025,respectively, thenumberofrequireddatapointsfromeachsurveyunittoperformthe evaluation,asobtained fromMARSSIMguidance(Table5.5)is18.
ForstaticmeasurementlocationsonClass1andClass2roomsurfaces,arandomstartpoint will beidentifiedonthefloorandadditionalmeasurementlocationswillbesystematically selectedon atriangularspacingfromthatstartpoint.Spacingdistance,L,isdeterminedby
L=[(SurveyUnitArea)/0.866xnumberofdatapoints]0.5
Internal surfacesofductwork and piping will be accessed, scanned, and static measurements performedattheentranceanddischargeandadditionalpointsatafrequencyof1 measurement per4m2ofinternalsurfacearea.
Static measurement locations on Class 3 room surfaces will be at locations of highest contaminationpotential,asselectedbyprofessionaljudgment.
6.4 FSSSurveyInstrumentation Table7isalistofradiologicalsurveyinstrumentationthatwillbeusedtoimplementtheAGN201M reactor facility surveys. These instruments will be maintained, calibrated, and operated in accordancewithwrittenprocedures.Forapplicationtounrestrictedrelease,instrument response (efficiency)isbasedonNIST-traceablesourcesofTc99(betaEMAX=292keV)andTh 230(alpha E=4.68MeV). Theenergiesoftheseradionuclidesarerepresentativeofthe dominantpotential contaminants.Notethatthe126cm24368gasflowproportionaldetectorshavedetectorefficiencies andambientbackgroundcountratesthatareidenticaltothe100cm24393dualphosphorscintillation detectorsusedforhealthphysicssurveysduringfacilitypreparationsforrelease;surveydataaredirectly comparable.
18
Table7.
InstrumentationforReleaseSurveys Detector Display Application Ludlum4337 Ludlum2360 Alpha/betascans Ludlum4368 Ludlum2360 Alpha/betascans Ludlum4368 Ludlum2360 Alpha/betastaticmeasurements Ludlum4310 Ludlum2929 Removablealpha/betameasurements (scaler)
Ludlum19 N/A Gammascans/directgammameasurements
For field measurement applications, calibration represents 2 response. Effects of surface conditionsonmeasurementsareintegratedintotheoverallinstrumentresponsethroughuse ofa sourceefficiencyfactor,inaccordancewiththeguidanceinISO75031(Ref7)and NUREG/CR 1507(Ref8). Defaultsurfaceefficienciesof0.25foralphaemittersand0.25forbeta emitterswill beused.
Detection sensitivities are estimated using the guidance in MARSSIM and NUREG/CR1507.
Instrumentation and survey techniques are chosen with the objective of achieving detection sensitivities of <50% of the criteria for structure surfaces, for both scanning and direct measurement.Thesedetectionsensitivitiesassureidentificationofareaspotentiallyexceedingthe establishedproject criteria. Minimumdetectableactivitylevels(refertoAppendixA)forthis surveysatisfythe Table1values.
6.5 SurfaceScans Scans of surfaces will be performed to identify locations of potential residual surface contaminationandinducedactivity. Gasproportionaldetectorswillbeusedforalphaandbeta scans. ALudlumModel4337gasproportionaldetector(580cm2)willbeusedwitha Ludlum Model2360scaler/ratemetertoscanthefloorsurfaces. Surfacesnotaccessiblewith thislarge detector will be scanned with the smaller Ludlum Model 4368 gas proportional detectors (126cm2) used with Ludlum Model 2360 scaler/ratemeters. Alpha/beta scanning will be performedby maintainingthedetectorwithin1/4inchofthesurfaceandpassingthedetectorover thesurface atarateofapproximately1/2detectorwidthpersecond,whilemonitoringtheaudible outputof thescaler/ratemeterforimmediateidentificationofincreasesincountrate. When2 alpha countsaredetectedwithinapproximately2seconds,thedetectormovementwillbehalted atthelocationforapproximately10 secondstodetectapossibleelevatedcountrate.Thisis consistentwithAppendixJguidanceintheMARSSIMdocument(NUREG1575).
ALudlumModel19gammascintillationdetectorwillbeusedforgammascans. Generalarea gammamonitoringwillbeperformedwiththedetector approximately1mabovethefloor.
19
6.6 StaticSurfaceActivityMeasurements
StaticmeasurementofalphaandbetasurfaceactivitywillbeperformedusingLudlumModel 43 68gasproportionaldetectorswithLudlumModel2360scaler/ratemeters.Measurementswillbe conductedbyholdingthedetectorinpositionwithin1/4inchofthe surfaceandintegratingthe countovera2minuteperiod.Twomeasurements,1shieldedand1unshielded,willbeperformed ateachstaticmeasurementlocation,withthenetcountratebeingthedifferencebetweenthe twomeasurements,foralphaandbetadetection.
6.7 RemovableContaminationMeasurements
Asmearforremovableactivitywillbeperformedateachstaticsurfaceactivitymeasurement location. A100cm²surfaceareawillbewipedwithanominal2inchdiameterclothsmear,using moderatepressure.
6.8 SamplesandAnalyses
SmearswillbeanalyzedonsiteforgrossalphaandgrossbetaactivityusingaLudlumModel 2929 scalerwithaModel43101dualscintillationdetector(orequivalentinstrumentation).
6.9 QualityAssurance/QualityControl
Measurements will be performed in accordance with the survey plan by qualified personnel followingwritteninstrumentoperatingprocedures. InstrumentcalibrationpracticesmeetANSI standardsanddailybackgroundandsourceresponsechecksofinstrumentswillbeperformeddaily.
Forqualitycontrolpurposes,replicatestaticandremovableactivitymeasurementswere obtained at2locationsineachsurveyunit.
7.0 DATAEVALUATION
Surface contamination measurement data will be adjusted for background contributions and convertedtounitsofnetcountsperminute.Datawillbeassessedtoverifythatthetype, quantity, andqualityareconsistentwiththesurveyplananddesignassumptions.Individual datavalueswill becomparedwiththecountratelimitderivedfromNUREG1757surfacecontaminationscreening values for 60Co and the TAMU criteria of twice background. Residual contamination limits establishedfortheproject(seeSection4)arepresentedinTable3,includingacomparisonofthe TAMUlimitsandtheNRCscreeningvalues.
EvaluationofvolumetricsampledataisdiscussedinSection4,RadionuclideContaminantsand Criteria
20
8.0 ISOLATIONANDCONTROL Followingcompletionofthereleasesurvey,thefacilitywillbeisolatedandaccesscontrolled until NRCapprovalforunrestrictedreleaseisreceived. ItisrecognizedthattheNRCmay chooseto conduct independent surveys to confirm the findings of this survey. These areas will not be availableforgeneralaccessorworkuntilNRCapprovalforunrestrictedreleaseisobtained.
9.0 REPORT
Adraftreportdescribingthesurveyproceduresandfindingswillbeprepared. Thisreportwill standaloneandprovideacompleterecord,documentingthefacilitysradiologicalstatus satisfies established project criteria and that the facility is therefore ready for unrestricted release.
AppendixB isasampleofthereportcontent. Thereportwillincludeallsampledatasupporting this determination.Commentsonthedraftreportwillberesolvedandafinalreportpreparedand submittedtotheNRCforreviewandapproval.
10.0 REFERENCES
- 1. RadiologicalSafetyProgramManual,RadiologicalSafetyEnvironmentalHealthand Safety Department,TexasA&MUniversity,July2004.
- 2. Texas Regulations for acceptable contamination levels for unrestricted use, 25 TAC§289.202(ggg)(6).
- 3. MultiAgencyRadiationSurveyandSiteInvestigationManual(MARSSIM),NUREG1575 (Rev.
1),U.S.NuclearRegulatoryCommission,2000.
- 4. A Nonparametric Statistical Methodology for the Design and Analysis of Final Status DecommissioningSurveys,NUREG1505(Rev1)U.S.NuclearRegulatoryCommission, 1998.
- 5. EvaluationofSurfaceContamination-Part1:BetaEmittersandAlphaEmitters,ISO 75031, InternationalOrganizationforStandardization,1988.
- 6. MinimumDetectableConcentrationswithTypicalRadiationSurveyInstruments for Various ContaminantsandFieldConditions,NUREG/CR1507,U.S.NuclearRegulatory Commission, 1997.
- 7. ConsolidatedDecommissioningGuidanceCharacterization,Survey,and Determination of RadiologicalCriteria,NUREG1757,Vol.2,Rev.1,U.S.Nuclear RegulatoryCommission,2006.
A1
AppendixA
Measurement/DetectionSensitivitiesofSurveyTechniques
ThemethodsforcalculatingsurveydetectionsensitivitiesarepresentedinMARSSIM(Ref1)and NUREG1507(Ref2).Detectorparametersusedinthesecalculationarebackgroundcountrate, efficiency(instrumentresponseandsurfacecorrectionfactors),anddetectorarea.Thefollowing tablepresentstypicalvaluesoftheseparametersfordetectorsusedfor surveysofconcrete structuresurfacesoftheAGNreactorfacility.Backgroundlevelsforconcretearethehighestfor surfacemediaremaininginthisfacility,andthereforedirectmeasurementsonothermediawill bemoresensitivethanthosepresentedhereforconcrete.
Detector/
Instrument Probe Area (cm2)
Background(cpm)
Detectorefficiency Surfacecorrection
alpha beta alpha beta alpha beta 4337 580 9
300 0.50 0.46 0.25 0.25 4368 126 3
250 0.36 0.36 0.25 0.25 2929 N/A 1
25 0.25 0.20 N/A N/A
AlphaScans
SurfacescansforalphaactivityareconductedusingLudlumModel4337andModel4368gas proportional detectors, coupled with Ludlum Model 2360 scaler/ratemeters. MARSSIM recommendstheuseofPoissonsummationstatisticstoestimatetheprobabilityofdetectinga smallnumberofcountsthatmayindicatethepossiblepresenceofalphacontaminationduringa relativelyshortobservationperiod.Theequationforestimatingtheprobabilityofdetecting1or morecountsis:
P(n>1)=1-e[((GE+B)t))/60]
where:
P(n>1)=Probabilityofgetting1ormorecountsduringthetimeinterval G=Sourceactivity(disintegrationsperminute,dpm)
B=Backgroundcountrate(countsperminute,cpm)
E=Detectorefficiency(counts/disintegration) t=Dwelltimeoversource(sec)
Theprobabilityofdetecting2ormorecountsisgivenby:
P(n>2)=1-(e[((GE+B)t)]/60]-((GE+B)(t))/60).e[((GE+B)t)]/60]
Using these parameters, detection probability calculations for a contamination level of 100
A2
dpm/100cm2wereperformedforascanrateof1/2detectorwidthpersecond(i.e.,dwelltimesof 2seconds)Theprobabilitiesofdetectingasinglealphacountduringa2seconddwelltimeare approximately33%forthe4368detectorand52%forthe4337detector.Becauseofthehigher backgroundcountrateassociatedwiththe4337floormonitordetector,MARSSIM(AppendixI) recommendsusing2countsasascreeningvaluewhenscanningforalphacontamination.The probability of detecting 2 counts with the larger detector increases to approximately 82%.
Whenever a count is detected, the detector is paused over the surface for 10 seconds to determine whether there is actually elevated alpha activity present, in which case, a static measurementisthenperformed.A10secondpauseresultsina90%orgreaterprobabilityof identifyingthepresenceofalphaactivityexceeding100dpm/100cm2.Althoughthecalculated scandetectionprobabilitiesmayappearrelativelylow,itshouldbenotedthathistoricrecords andcharacterizationsurveyshavenotidentifiedanypotentialforalphacontaminationinthis facility.
AlphaActivityStaticMeasurements
Staticmeasurementsofalphasurfaceactivityareperformedusing4368detectors,withthesame background and response characteristics as indicated above for alpha scanning. A static measurementisperformedbyplacingthedetectoronthesurfaceandallowedtointegratethe countforaperiodof2minutes.Theminimumdetectablealphacontaminationlevel(MDC)is calculatedasfollows:
MDC=[3+4.65(BKGD)1/2]/(efficiencyfactors)(detectorarea/100)(counttime)
Theresultingvalueisapproximately63dpm/100cm2.
BetaScans
SurfacescansforbetaactivityareconductedusingLudlumModel4337andModel4368gas proportional detectors, coupled with Ludlum Model 2360 scaler/ratemeters. The detector is passedoverthesurfaceatarateof1/2detectorwidth/sec,whilemaintainingthedistancefrom thedetectortothesurfaceatapproximately0.5cm.Theaudiblesignalfromtheinstrumentis monitoredbythesurveyor.Detectablechangesinthecountratearenoted,andtheimmediate arearesurveyedatareducedspeedtoconfirmthechangeinaudiblesignaland,ifapplicable,to identifytheboundaryoftheimpactedarea.Theminimumdetectablecountrate(MDCR)isa functionofthebackgroundcountrate(BKGD)incountsperminute(cpm)andthetime(i)in secondsthatthedetectoriswithincloseproximitytothesourceofradiation.Equation66of NUREG1507providesthefollowingrelationship:
MDCR=d[BKGD*i/60]1/2*60/i
Ahighprobability(95%)oftruedetectionistheobjective,andthesurveyiswillingtoaccepta highprobabilityoffalsepositivedetections(60%)withresultinginvestigations.Thevalueofdis selectedfromTable6.1inNUREG1507tobe1.38.
A3
Toaccountforlessthanidealsurveyperformance,asurveyorefficiencyfactor(p)of(0.5)1/2was alsoincorporatedintothefinalcalculationofbetascansensitivityasfollows:
(B2)
(0.5)1/2*(cpm/dpm)(probearea/100)
Theresultingvaluesareapproximately1500dpm/100cm2forthe4368detectorandanaverage of390dpm/100cm2forthe4337detector.Ifonlyasingle100cm2areaispresent,thescan sensitivityforthe4337detectorwouldbeapproximately2280dpm.
BetaActivityStaticMeasurements
Static measurements of beta surface activity are performed using 4368 detectors. A static measurementisperformedbyplacingthedetectoronthesurfaceandallowingittointegratethe countforaperiodof2minutes.Theminimumdetectablebetacontaminationlevel(MDC)is calculatedasfollows:
MDC=[3+4.65(BKGD)1/2]/(efficiencyfactors)(detectorarea/100)(counttime)
Theresultingvalueisapproximately470dpm/100cm2.
RemovableAlphaandBetaActivityMeasurements
Smearsforremovableactivityarecountedfor2minutesinaLudlumModel2929alpha/beta counter.Thebackgroundsare1alphacpmand25betacpm;4detectionefficienciesare0.25 alphaand0.20beta.Usingthesameequation(withoutprobeareacorrection)asabovefordirect measurementsyieldsremovableactivityMDCsofapproximately19alphadpm/100cm2and90 betadpm/100cm2.
References
- 1.
MultiAgencyRadiationSurveyandSiteInvestigationManual(MARSSIM),NUREG 1575(Rev.1),USNuclearRegulatoryCommission,2000.
- 2.
MinimumDetectableConcentrationswithTypicalRadiationSurveyInstrumentsfor VariousContaminantsandFieldConditions,NUREG/CR1507,USNuclearRegulatory Commission,1997.
B1
APPENDIXB
SampleOutlineofReleaseSurveyReport
1.0 ExecutiveSummary 2.0 Introduction 3.0 PurposeandScope 4.0 SiteDescription 5.0 RadionuclideContaminantsandCriteria 6.0 SurveyApproach 7.0 SurveyResultsSummary 8.0 Conclusion 9.0 References
Attachments
Fielddata(electronic)