ML20247D997
| ML20247D997 | |
| Person / Time | |
|---|---|
| Issue date: | 08/31/1989 |
| From: | Shum E NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Gray R Battelle Memorial Institute, PACIFIC NORTHWEST NATION |
| References | |
| REF-WM-3 NUDOCS 8909150181 | |
| Download: ML20247D997 (22) | |
Text
.
Dr. Rob;rt H. Gray l
,Ba.ttelle,. Pacific Northwest'
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Laboratories L
PO. Box 999, K1-30 AUG 311939 i
Richland, WA 99352
Dear Dr. Gray:
Enclosed are the three manuscripts and diskettes titled:
1.
Environmental Monitoring for Low-Level Radioactive Waste Disposal Facilities (Oral presentation) ;
'2.
The Decommissioning of Nuclear Facilities Involving the Operation of Uranium and Thorium (Oral presentation); and 3.
Dose Assessment and Environmental Monitoring to Demonstrate Compliance with the EPA's Environmental Radiation Standards-Established for Nuclear Fuel Cycle Facilities (Poster presentation);
submitted for presentation at the Twenty-Eighth Hanford Life Sciences Symposium held at Richland, Washington on October 16-19, 1989.
The registration form for the symposium is also enclosed.
If you have any questions on these manuscripts, please call me at (301)492-0607.
ofid"gf Edward Y. Shum, PhD Technical Branch Division of Low-Level Waste Management and Decommissioning, NMSS
Enclosure:
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.e ENVIRONMENTAL MONITORING FOR LOW-LEVEL RADI0 ACTIVE WASTE DISPOSAL FACILI L
Edward Y'. Shum, Robert J. Starmer, Kristin Westbrook, and Michael H. Young Division of Low-Level Waste Management and Decommissioning Office of Nuclear Material Safety and Safeguards i
U.S. Nuclear Regulatory Commission Washington, DC 20555 Abstract The U.S. Nuclear Regulatory Commission staff has prepared a Branch Technical Position (BTP) paper concerning the environmental monitoring program for a low-level radioactive waste disposal facility. -The BTP is intended to provide guidance on what is required tv Section 61.53 of 10 CFR Part 61 for licensees submitting a license application.
In general,.the environmental monitoring program consists of three phases:
pre operational, operational, and post-operational.
Each phase of the monitoring program should be designed to fulfill the specific objectives defined in the BTP.
During the pre-operational phase, the' objectives of the program are to provide site characterization information, to demonstrate site suitability and acceptability and to obtain background or baseline information.
During the operational phase, the emphasis on measurement shifts.
Monitoring data is obtained to demonstrate compliance with regulations, the dose limits of 10 CFR Part 61 or applicable EPA standards.
Data'is also used to update important pathway parameters to improve predictions of site performance and to provide a record of performance for public information.
The post-closure environmental monitoring program emphasizes measurements to demonstrate compliance with the site closure requirements and continued compliance with the performance objective for release.
The data is used to support evaluation of long-term impacts to the general public and for public information.
Guidance is also provided in the BTP on choice of constituents to measure, setting action levels, relating measurements to appropriate actions in a corrective action plan, and quality assurance.
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4 1 INTRODUCTION The Atomic Energy Act of 1954 and the Energy Reorganization Act of 1974 assign to.the U.S. Nuclear Regulatory Commission (NRC) the responsibility for licensing and regulating commercial nuclear facilities.
The licensing requirements for near-surface disposal of low-level radioactive wastes (LLW) are in Part 61 of Title 10 of the Code of Federal Regulations (10 CFR Part 61)2 The basic NRC requirement for near surface LLW disposal site monitoring is in 10 CFR 61.53.
The regulation calls for environmental monitoring during the preoperational, operational, and postoperational stages of the facility.
The purpose' of the staff's technical position paper is to provide general guidance to applicants, their consultants and regulatory authorities (NRC Agreement States) on design of a monitoring program for low-level waste disposal facilities.
The
- primary objective of environmental monitoring is to provide assurance that the performance objectives in 10 CFR Part 61 are met.
The technical position paper is not intended to be a handbook of detailed or mandatory procedures and it must be stressed that because each site has unique topography, meteorology, demography, and geohydrogeology, a detailed environmental monitoring program for a low-level waste disposal facility must be tailored to the site specific operating and environmental conditions.
In the design of an environmental monitoring program, there is no substitute for good professional judgement combined with a thorough knowledge of the local environment (ICRP)2 This paper summarizes the technical position and provides insight into the opinions and expectations of NRC staff for the acceptance review of the applicant's environmental monitoring program.
For more detailed design and implementation of an environmental monitoring program, NRC staff has provided references 3 s in the technical position paper for further l
guidance.
2 ENVIRONMENTAL MONITORING PROGRAM OBJECTIVES 2.1 Regulatory Requirements The requirements pertaining to an environmental monitoring program are described in 10 CFR Section 61.53, " Environmental Monitoring":
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"(a)
At the time a. license, application is submitted, the applicant shall have conducted a preoperational monitoring program to provide basic-environmental data on the disposal site' characteristics.
The appli-cant shall obtain information about the ecology, meteorology, climate, hydrology,' geology, geochemistry, and seismology of the dispoal site.
For those characteristics that are subject to seasonal variation, data must cover at least a twelve month period.
(b)l The licensee must have plans for taking corrective measures if migra-tion of radionuclides would indicate that the performance objectives of Subpart C may not be met.
(c)
During the land disposal facility site construction and operation, the licensee _shall maintain a monitoring program.
Measurements and
-observations must be made and recorded to provide data to evaluate the.
potential health and environmental impacts during both the construction and the operation of the facility and to enable the evaluation of long-term effects and the need for mitigative measures.
The monitoring system must be capable of providing early warning of releases of radionuclides from the disposal site, before they leave the site boundary.
(d) After the dispoal site is closed, the licensee responsible for postoperational surveillance of the disposal site shall maintain a monitoring system based on the operating history and the closure and stabilization of the disposal site.
The monitoring system must be capable of providing early warning of releases of radionuclides from the disposal site before they leave the site boundary."
2.2 Objectives of Environmental Monitoring program The principal objectives of the three phases of an environmental monitoring program for a low-level radioactive waste disposal facility are as follows:
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- Preoperational Monitoring Objectives-i
'1.
Provide' site characterization information.
2.
-Demonstrate site suitability and acceptability.
3.
Obtain background or baseline ~ data.
Operational Monitoring Objectives 1.
Demonstrate compliance with applicable environmental radiation standards-2.
'Obtain data on critical pathway parameters to allow more accurate evaluation of radiation dose to the general public.
3.
Provide records for public information.
Postoperational Monitorino Objectives 1.
Demonstrate compliance with site-closure requirements.
2.
Provide data to support long-term impact evaluation, such as long-term impacts on groundwater.
3.
Provide records for site closure and for public information.
GEN'ERAL GUIDANCE'ON PRE 0PERATIONAL ENVIRONMENTAL 3
The primary. purpose of the preoperational program is to characterize the site environment.
The program consists principally of collecting new or existing monitoring data to evaluate the geological, hydrogeological, climatological, ecological, radiological, and nonradioactive pollutant environments of the site and the surrounding area.
Characterization is needed to demonstrate the site's acceptability and suitability for LLW disposal, compared with other alternative sites in the applicant's site-selection process.
In the preoperational phase, environmental media are sampled and analyzed to provide background or baseline data to characterize the site environment.
Some of the environmental sampling can be used as indicators for long-term impact assessment.
For some character-istics, generally those which may be subject to seasonal changes, the program must be continued for at least one year and should be extended through NRC's 4
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' license review period of from 12 to 15 months.
The typical measurements of-
.various parameters covering the site characteristics are summarized in Table 1.
Table 1~
Site Characteristics and Typical Measurements Site Characteristics Typical Measurements Meteorology / Climatology Windspeed and direction; stability; precipitation; temperature; evaporation Groundwater Hydrology Rate and direction of water-table elevation; groundwater movement; movement of infiltrate; identification of aquifers and groundwater systems; hydraulic conductivity; background contaminant levels Surface Water Hydrology.
Runoff, infiltration _ rates; erosion rates; surface water discharge rates; surface water quality
-Geology / Seismology
' Stratigraphy, tectonics, seismicity; surface and trench mapping; geophysical borehold logging
- Geochemistry /Hyrdochemistry Water quality, ion-exchange capacity, Eh pH, distribution coefficient l -
Ecology Inventory of plants and animals (domestic, commercial, and natural)
Demography Population distribution by distance and sectors Land Use Inventory of agricultural, recreational, commercial and other uses Background Radiation Direct radiation; soil, air and water i
concentration levels i
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'4' GENERAL GUIDANCE ON OPERATIONAL ENVIRONMENTAL MONITORING The principal purposes.of.the operational environmental program are to monitor site performance and to demonstrate compliance with applicable standards. 'The
.j following monitoring discussion will emphasize radiological aspects resulting I
from operation.
Non radiological constituents are discussed only to the extend E
that'they affect transport of radionuclides and can be used.as~early warning indicators of waste migration, into groundwater.
t.
4.1. Considerations in the Design of the Operational Environmental-Monitoring Program
.I i
. Pathway Analysis The-knowledge of pathways for waste ~ migration from the burial site to members of the public are important in the design of an operational environmental-monitoring program.
By performing a pathways analysis which consists of (1) pathways identification, (2) pathways modeling and (3) dose calculation, the critical pathways for exposure of humans can~ be identified.
An important objective of the. operational program is to monitor critical pathways, by selecting appropriate environmental sampling media and sampling locations, to ensure that human exposure can be measured or calculated as accurately as possible.
The critical pathways where monitoring efforts should be concentrated are dependent on waste stream characteristics, facility operation and design, and site environmental factors.
The detail or level of monitoring a particular pathway also depends on the performance assessment to demonstrate compliance with applicable standards.
Critical Nuclides and Groups The " critical" nuclides and groups refer to the radionuclides most subject to release and population groups potentially subject to the greatest exposure.
To d
identify critical radionuclides, the characteristics of the wastes that are to be buried at the facility must be known.
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!c Measurement'of Parametersin the. Environment Physical Parameters L
Data collected to characterize fundamental parameters of the site such as-geology, ecology, hydrology, etc. may not be repeated during the operational phase.
Howev~er, time variant parameters, such-as wind speed, direction, precipitation.and evaporation data which are important in dose assessment should be remeasured and evaluated periodically.
Radiological Measurements
-The radiological measurements include direct ~ radiation and the sampling and measuring radiological contaminants in air, groundwater surface water, soil and sediment, flora and fauna.
The sample locations, sampling frequency, and radionuclides measurement are site-specific and are determined on a case-by-case basis.
In general, samples should be collected to determine background levels, areas of maximum impact, where people can be exposed, and where measurements can be useful in interpreting the results of the overa11' monitoring program.
The sampling program depends on the critical pathway determination which is site-specific and the compliance requirements.
Radionuclides to be measured in the sampling media depend on the waste characterization and pathway consideration-and compliance requirements.
Action Levels The applicant.should set action levels on the key environmental media to provide early warning and to ensure that mitigating measures are taken in a timely manner and in compliance with 10 CFR 61.53(b).
The following types of action levels should be considered:
1.
Triggering Level:
defined as the~ concentration of radioactivity or chemical indicators above which an investigation is required.
2.
Reporting Level:
defined as the concentration of radioactivity or cFemicals
. that exceed or are about to exceed regulatory standards.
A report should be sent to NRC or state on the monitoring results, its investigation and findings and mitigating measures taken to correct the problem.
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5 GENERAL GUIDANCE ON POSTOPERATIONAL ENVIRONMENTAL MONITORING After closure of a LLW disposal sit'e, it is expected that the facility buildings and land has been properly decommissioned and that residual contamination has been decontaminated to acceptable levels.
Disposal units are capped to. limit infiltration, to protect intruders and to prevent bio-intrusion.
Then the' site is placed under institutional control. 'The postoperational monitoring ensures
~that the site continues to' meet closure requirements.
Physical surveillance should be conducted periodically after site closure.
The surveillance program should provide for physical-inspection of the site and the performance' of any required repairs to maintain the site integrity.
This
' includes the repairing, and maintaining of the perimeter fence, backfilling subsidence of the trenches, and repairing damage caused by erosion.
After site closure, the primary path for radionuclides release to the environment is through the groundwater pathway.
The groundwater monitoring program for the operational phase should be continued during the inititial period after site closure,'and can be gradually reduced if no potential problem is identified.
The analysis of chemical indicators and radioactivity should be continued. 'If subsurface water is known to reach ground surface and eventually enter any streams, l
rivers, or lakes, these water bodies should be monitored.
Vegetation (parti-cularly deep-root plants) should be sampled periodically to determine any uptake of radionuclides.
Burrowing animals or fecal pellets should also be sampled and i
analyzed.
Such plants and animals serve to indicate whether the biological barrier continues to be effective.
6 QUALITY ASSURANCE / QUALITY CONTROL The applicant's environmental monitoring program should include a quality assurance / quality control. program.
These programs are needed to identify deficiencies in the sampling and measurement processes to those responsible for these operations so.that corrective action can be taken, and to obtain some measure of' confidence in the results of the monitoring programs in order to assure the regulatory agencies and the public that the results are valid.
The 1
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applicant should refer to NRC's Regulatory Guide 4.157 and NUREG-09458 for the design of a QA/QC program.
REFERENCE 1.
Code of Federal Regulations, Title 10, Part 61:
Licensing Requirements for Land Disposal of Radioactive Waste, U.S. Nuclear Regulatory Commission.
2.
International Commission on Radiological Protection - Principles of Monitoring for Radiation Protection of the Population, Publication 43, 1984.
3.
Department of Energy - Site Characterization Handbook - National Low-Level Waste Management Program, DOE /LLW-67T, 1988.
4.
Department of Energy - Low-Level Radioactive kaste Management Handbook Series - Environmental Monitoring for Low-Level Waste-Disposal Site, DOE /LLW-13Tg, 1989.
5.
U.S. Nuclear Regulatory Commission - Recommendations to the NRC for Review Criteria for Alternative Methods of Low-Level Radioactive Waste Disposal Environmental Monitoring and Surveillance Program, NUREG/CR-5054, 1988.
6.
U.S. Nuclear Regulatory Commission - Branch Technical Position -
Low-Level Waste Licensing Branch - Site Suitability, Selection and Characterization, NUREG-0902, 1982.
7.
U.S. Nuclear Regulatory Commission - Quality Assurance for Radiological Monitoring Program (Normal Operations) - Effluent Streams and the Environment, Reg. Guide 4.15, 1979.
8.
U.S. Nuclear Regulatory Commission - Quality Assurance Guidance for Low-level Waste Disposal Facility, NUREG-1293, 1989.
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if THE DECOMMISSIONING OF NUCLEAR FACILITIES INVOLVING t'.
THE OPERATION OF URANIUM AND THORIUM Edward Y., Shum and Stanley M. Neuder' Office of-Nuclear Material. Safety and Safeguards U.S. Nuclear Regulatory Commission Washington, DC 20555 ABSTRACT When.a licensed nuclear facility. ceases its operation, the U.S. Nuclear Regulatory Commission (NRC) is responsible to ensure that the facility and its site be decontaminated to an acceptable level such that it is safe to release
.that facility and site.for unrestricted public use.
Since specific environmental standards or broad Federal guidelines. governing the release of residually radio-active contamination have not been issued, the NRC has developed Ad Hoc clean-up criteria for the decommissioning of nuclear facilities involving' operations'with uranium'and thorium.
The. clean-up criteria include the decontamination of-
.(1) building and equipment,=and (2) land or soil. 'This paper describes the Eclean up' criteria used and their rationale; the procedures for the decommissioning of these. facilities; radiological survey designs and procedures; radiological monitoring and measurement; and cost effectiveness to demonstrate compliance.
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l 1 INTRODUCTION i
l In the decommissioning of a nuclear facility, two sets of clean-up criteria are
)
generally applied.
One set of criteria is to define acceptable residual levels I
of radioactivity for the decontamination of facility building and equipment; the other set of criteria is to define acceptable residual levels of radioactivity for land or soil clean-up.
The U.S. Nuclear Regulatory Commission (NRC) has i
developed Ad Hoc clean-up criteria for the decommissioning of nuclear facilities involving operations with uranium and thorium.
The following sections describe the NRC's criteria and the procedures for decontamination of these facilities to demonstrate compliance of these criteria.
2 CRITERIA FOR CLEAN-UP 2.1 Building and Equipment The guidelines specifying acceptable surface contamination levels for uranium and thorium are contained in NRC's document titled " Guidelines for Decontamination of Facilities and Equipment Prior to Release for Unrestricted Use or Termination of Licenses for Byproduct, Source or Special Nuclear Material - July, 1982"1 Table 1 summarizes the acceptable surface contamination levels for uranium and thorium.
2
e Table 1 Acceptable Surface Contamination Levels for Uranium and Thorium Nuclides Average Maximum Removable U nat, U-235, U-238 5,000 dpm a/100cm2 15,000 dpm a/100cm2 1,000 dpm a/100cm2 and associated decay products Th-nat and 1,000 dpm/100cm2 3,000 dpm/100cm2 20 dpm/100cm2 associated decay products Beta gamma emitters 5,000 dpm sy/100cm2 15,000 dpm sy/100cm2 1,000 dpm sy/100cm2 Note 1.
Wh'ere surface contamination by both alpha-and beta gamma emitting nuclides exists, the limits established for alpha-an'd beta gamma-emitting nuclides should apply independently.
Note 2.
The average and maximum radiation levels associated with surface contamination resulting from beta gamma emitters should not exceed 0.2 mrad /hr at 1 cm and 1.0 mrad /hr at I cm, respectively, measured through not more than 7 milligrams per square centimeter of total absorber.
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The NRC is currently working on revised residual radioactive contamination limits for decommissioning based'on a dose limit.
Prior to the publication and acceptance of tha revised limits, the above criteria are to be used for the routine decontamination of these facilities.
- 2. 2 Land - Soil For clean-up of land or soil, the NRC has established target criteria specified as Option 1 in the NRC's Branch Technical Position on the Disposal of Residual 2
The clean-up criteria'are summarized in Table 2.
Table 2 Clean-up Criteria for Land - Soil Kind of Material Concentration (pCi/g)
Natural Thorium (Th-232 + Th-228) with 10 daughters present and in equilibrium Natural Uranium (U-238 + U-234) with 10 daughters present and in equilibrium Depleted Uranium, natural uranium with daughters separated 35 Enriched Uranium 30 In establishing soil decontamination criteria, NRC staff has applied the following rationale and objectives:
a.
The radiation exposure to individuals using the land must be within current NRC and EPA radiation exposure guidelines including the requirement that these exposures be as low as reasonably achievable.
b.
These criteria must be consistent with criteria currently being applied or developed for similar type situations.
The clean up criteria for natural uranium and thorium with daughters in equilibrium are based on EPA's mill tailings clean-up standards (40 CFR Part 192)3 The clean-up criteria for depleted and enriched uranium are based on EPA's proposed guidance on dose limits for persons exposed to transuranium elements in the general environment (EPA - 1977)4 4
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= 3 DECOMMISSIONING PROCEDURES
- The general. requirements and procedures.for decommissioning nuclear facilities are specified in NRC's final rule on decommissioning (53 FR 24108 - June 27, 1988)5 The.. specific requirements for decommissioning of the above-mentioned I
facilities are specified'in 10 CFR Parts 30, 40 and 70 covering byproduct, 1
- source material and special nuclear material licenses.
Prior to the initiation of. decommissioning work, the licensee is' required to submit a decommissioning plan for review and approval.
The decommissioning plan should
. include the following items:
(1) a desc'ription of decommissioning procedures to be used including plans for processing.and disposing of the radioactive waste; (2) a description of methods used to ensure the safety of' workers and members of the public; (3). a plan.for a final. radiation survey to ensure that the property is suitable for release for unrestricted use; (4) a cost estimate to ensure that adequate funds will be available before decommissioning activities are initiated; and
' (5)- a description of quality assurance and safeguards provisions if appropriate for the specific license, such as for special nuclear material license.
The following sections emphasize the radiological surveillance' procedures to demonstrate compliance with the above criteria for the unrestrictive release of the facility and the site.
l-3.1 Radiological Survey of Building and Equipment
{
l Instrumentation 1.-
All instruments used in the survey should have been calibrated by qualified personnel, using accepted practices under the license.
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e 2.:
Instruments'should have sufficient detection sensitivity so that the
. measured data can be'used to verify compliance with acceptable contami-
-nation levels.. Guidance concerning the detection sensitivity for different types of radiation' detection instruments is included in Chapter 4 of NUREG/
CR-20826 and NCRP Report No. 50, Environmental-Radiation Measurements.7
. Scope of Surveys All indoor areas (such as floors, walls, ceilings, equipment,' furniture) of the building and outdoor areas (such as roofs, ground area, etc.) should be surveyed
'for' radiation contamination levels and reported in the proper units in the appli-cant!s survey report.
Prior to surveying the facility it should-be divided into.
specific areas suitable for surveying.
Guidance conce'rning the choice of grid sizes and the total sample size required can be found in Chapter 3 of NUREG/
- CR-20826 In each survey block which is formed by the grid, the following set of measurements should be conducted and reported:
(a).' Direct readings for alpha and beta gamma:
The average and the maximum contamination levels at the surface should be reported in dpm/100 cm2 for the alpha counting mode; and in dpm/100 cm2 and prads/hr for.the beta gamma counting mode.
(b). Smear testing for determining alpha and beta gamma removable contamination levels should be reported in dpm/100 cm,
2 3.2. Radiological Survey for Land - Soil Sample Collection and Measurement Acceptable. procedures for sample collection and measurement can be referred to
-those described in NC. EG/CR-20826 Prior to decommissioning work, it is import-ant that split samples of soil should be sent for analysis to NRC or its contractor for comparison of results.
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Land Area Survey A.
Surface l
(1) Samples of surface (0-15 cm) soil should be collected, systematically, from each 10 m x 10 m grid block for all affected areas; samples from the block center and 4 points, midway between the center and the block corners, will be composited for analysis.
An affected area is an area that there is a high potential for contamination due to plant operation.
Grid blocks for unaffected areas can be sampled and analysed in a random manner.
(2) Exposure rate measurements will be made at the surface and at 1 m above the surface at locations of soil sampling as above.
(3) Beta gamma radiation levels at 1 cm above the surface should be measured at locations of soil sampling.
(4) Composite samples of sediment should be obtained from lagoons and outfalls.
B.
Subsurface Subsurface soil sample measurements are required if there is any reason to suspect that subsurface contamination exists in the outdoor area or under the building.
Standard core sampling techniques may be used in the suspected con-taminated area to assess the subsurface soil contamination as a function of depth.
The existence of any of the following conditions may require analysis of subsurface samples:
(i)
Record showing that radioactive material has been buried at that area.
(ii)
Radioactive material (such as dry or liquid wastes) had been stored in the areas, underground, or in a pond.
(iii)
Any unexplainable, elevated, direct survey reading in the area.
(iv)
Creeks, streams, or underground transfer pipes were used as a pathway for contaminated liquid effluent release.
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C.
Water Samples
-Su:aples shall be taken from each source of potable water, surface water, and groundwater on the site, including water found in core holes drilled for subsurface soil samples.
Additional onsite and offsite groundwater samples may be required if there is any reason to suspect that subsurface contamination exists.
Demonstration of Compliance The NRC staff has considered the high cost in soil analysis for various radionuclides in the uranium and thorium series, and encourages the licensee to propose easy and less costly methods to demonstrate compliance.
The fcilowing are some of the acceptable methods to demonstrate compliance:
1.
Natural uranium with daughters in equilibrium: Ra-226 can be used as the dominant radionuclides because of the easily measurable gamma peak from Bi-214.
2.
Natural thorium with daughters in equilibrium: Ra-228 or Ac-228 can be used as the dominant radionuclides for the same reason as Ra-226 is used for natural uranium with daughters.
Radionuclides in the thorium series have strong gamma emitters and the NRC also has criterion for direct gamma radiation to limit exposure to less than 10 pR/hr above background measured at 1 m above surface.
If the licensee can correlate 10 pR/hr to less than 5 pCi/g of Ra-228, direct gamma radiation measurement, which is much cheaper than specific radionuclides measurements can be used to demonstrate surface soil compliance.
3.
For depleted uranium, gross alpha activity measurement in soil may be used for screening to demonstrate compliance.
4.
For enriched uranium, U-235 can be used ts the dominant radionuclides because of the easily measurable gamma peak provided that the ratio of U-234/U-235 is accurately measured.
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.The criteria listed:in Table.2 are aimed essentially at surface and subsurface soil decontamination..The issues arising from groundwater contamination are
~
dealt with on a case-by-case basis.
For example, if the ground water is or could be'used for. municipal drinking water, the EPA's drinking water standards
~on some of the' radionuclides, such as Ra-226 and Ra-228 will be applied.
At present, t'ere is no drinking water standard on uranium.
If the ground. water h
is not used for drinking water, then the full pathway analysis to meet a target
~
dose limit may be applied.
' REFERENCES 1.-
U.S. Nuclear Regulatory Commission - Guidelines for Decontamination of Facilities:and. Equipment Prior to' Release for Unrestricted Use or Termination of-Licenses for Byproduct, Source, or Special Nuclear
- Material, July 1982.
2.
U.S. Nuclear Regulatory Commission - Branch Technical Position on the Disposal of. Residual Thorium or Uranium, 46FR52061-3, October 23, 1981.
3.
U.S. Environmental Protection Agency - 40 CFR Part 192:
Standards for Remedial-Actions of Inactive Uranium Processing Sites, 52 FR 36000-8, September 24, 1987.
4.
U.S. Environmental Protection Agency - Interim Recommendations on Doses.
to Persons Exposed to Transuranium Elements in the General Environment, August 11, 1987.
i 5.
U.S. Nuclear Regulatory Commission - General Requirements for Decommissioning Nuclear Facilities, 53FR24108-56, June 27, 1988.
6.
U.S. Nuclear Regulatory Commission - Monitoring'for Compliance with Decommissioning Termination Survey Criteria, NUREG/CR-2082, June 1981.
7.
National Council on Radiation Protection and Measurements - Environmental L
Radiation Measurements, NCRP Report No. 50, December 27, 1976.
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DOSE ASSESSMENT AND ENVIRONMENTAL MONITORING TO DEMONSTRATE COMPLIANCE WITH THE EPA'S ENVIRONMENTAL RADIATION STANDARDS ESTABLISHED FOR NUCLEAR FUEL
' CYCLE FACILITIES Edward Y. Shum and Dennis M. Sollenberger Office cf Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission Washington, DC 20555 1.
INTRODUCTION On January 13, 1977, the Environmental Protection Agency issued regulations (40 CFR Part 190)1 setting forth environmental radiation standards for the uranium fuel cycle facilities.
The regulations specify that radioactivity in planned effluent releases, radon and its daughters excepted, from uranium fuel cycle plants be limited 'so that no member of the public will receive an annual dose equivalent of more than 25 millirems to the whole body, 75 millirems to the thyroid or 25 millirems to any other organs.
The Nuclear Regulatory Com-mission is responsible for assuring that the uranium fuel cycle plants licensed by the Commission meet the requirements of the standards.
The following sections describe the NRC's experience in enforcing the standards covering the uranium milling, UFs conversion and fuel fabrication facilities.
2.
DEMONSTRATION OF COMPLIANCE WITH THE ENVIRONMENTAL RADIATION STANDARDS To demonstrate compliance with the EPA's standards, the NRC staff has conducted a radiological assessment on each of these facilities using effluent release data as source terms.
The radiological assessment includes pathway analysis which consists of:
(1) pathway identification; (2) pathway modeling; and (3) dose calculation.
The annual maximum doses to the nearest resident can be calculated using the following information and methods:
j 1.
Measured effluent (air and liquid) released rates L
l 2.
Regulatory Guide 1.111 for atmospheric dispersion calculation2 L
3.
Regulatory Guide 1.109 for modeling of pathways and for dose calculation except that for the inhalation pathway, the dose conversion factors are 3
t generated using ICRP-30 methodology 4 1
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'4.
Regulatory Guide 3.51 - Calculational Models for Estimating Radiation Doses to Man from Airborne Radioactive Material Resulting from Uranium Milling Operations
- 5.
" Compliance Determination Procedures for Environmental Radiation Protection Standards for Uranium Recovery Facilities, 40 CFR Part 190".6 The above radiological assessment reveals that the air pathway is the critical pathway of radiation dose to man.
For certain unique facilities, it is found that these models may not be adequate to demonstrate compliance without the use of a supplemental environmental monitoring program.
The requirements for specific monitoring include: (1) continuous air sampling at the receptor location and composite air samples analysed for radionuclides; (2) measurement of uranium solubility in air particulate collected near the receptor and (3) measurement of particle size distribution in air particulate.
Details on environmental monitoring for uranium mill is presented in Regulatory Guide 4.14.7 3.
CONCLUSION In enforcing the EPA's environmental radiation standards for the uranium fuel cycle facilities, the NRC staff has learned that generic models developed may not be adequate to demonstrate compliance in some of the facilities.
Sometimes, rather sophisticated measurements and analysis have to be taken to provide more accurate estimation in the performance of dose calculation.
At present, all facilities are generally in compliance with the standards.
REFERENCE 1.
Code of Federal Regulation; Title 40, Part 190:
Environmental Radiation Protection Standards for Uranium Fuel Cycle Facilities, January 13, 1977.
2.
U.S. Nuclear Regulatory Commission - Regulatory Guide 1.111, " Methods for Estimating Atmospheric Transport and Dispersion of Gaseous Effluents in Routine Releases from Light-Water-Cooled Reactors," July,1977.
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3.
U.S. Nuclear Regulatory Commission - Regulatory Guide 1.109, " Calculation of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR Part 50, Appendix I, March, 1976.
4.
International Commission on Radiological Protection - Limits for Intakes of Radionuclides by Workers, ICRP 30, 1979.
5.
U.S. Nuclear Regulatory Commission - Regulatory Guide 3.51, " Calculational Models for Estimating Radiation Doses to Man from Airborne Radioactive Material Resulting from Uranium Milling Operation," 1982.
6.
U.S. Nuclear Regulatory Commission - NUREG-0859, " Compliance Determination Procedures for Environmental Radiation Protection Standards for Uranium Recovery Facilities, 40 CFR Part 190", 1982.
7.
U.S. Nuclear Regulatory Commission - Regulatory Guide 4-14
" Radiological / Effluent and Environmental Monitoring at Uranium Mills," 1980.
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