ML21140A363
| ML21140A363 | |
| Person / Time | |
|---|---|
| Site: | 07200011 |
| Issue date: | 04/20/2021 |
| From: | Gacke B Sacramento Municipal Utility District (SMUD) |
| To: | Document Control Desk, Office of Nuclear Material Safety and Safeguards |
| References | |
| DPG 21-053 | |
| Download: ML21140A363 (28) | |
Text
DPG 21-053 April 20, 2021 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Docket No. 72-11 Rancho Seco Independent Spent Fuel Storage Installation Renewed License No. SNM-2510 Powering forward. Together.
ANNUAL RADIOLOGICAL ENVIRONMENTAL OPERATING REPORT FOR 2020 Attention: Scott Morris In accordance with Rancho Seco Quality Manual, Appendix A, Section 1.5.2.2, SMUD is submitting the Rancho Seco 2020 Annual Radiological Environmental Operating Report for the period of January 1, 2020 through December 31, 2020.
If you or members of your staff have questions requiring additional information or clarification, please contact me at (916) 732-4812 or by email at Brad.Gacke@smud.org.
Brad Gacke Manager, Rancho Seco Assets
Enclosure:
Rancho Seco Annual Radiological Environmental Operating Report for 2020 cc:
NRG, Region IV (w/ enclosure)
William C. Allen, NRG (w/ enclosure)
RIC 1 F.099 (w/ enclosure) r1::Z5
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).)1-j _s s Rancho Seco Nuclear Generating Station I 14440 Twin Cities Road I Herald, CA 95638-9799 I 916.452.3211 I smud.org
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ANNUAL RADIOLOGICAL ENVIRONMENTAL OPERATING REPORT JANUARY - DECEMBER 2020 Rancho Seco ISFSI Herald, California 10 CFR Part 72 License Number SNM-2510
2020 ANNUAL RADIOLOGICAL ENVIRONMENTAL OPERATING REPORT TABLE OF CONTENTS LIST OF FIGURES........................................................................................................................................ 3 LIST OF TABLES.......................................................................................................................................... 4 I.
EXECUTIVE
SUMMARY
.................................................................................................................... 5 II.
LAND USE CENSUS.......................................................................................................................... 5 Ill.
RADIOLOGICAL IMPACT EVALUATION........................................................................................... 5 IV.
PROGRAM ANALYSIS RESULTS
SUMMARY
.................................................................................. 7 IV-A. ATMOSPHERIC MONITORING.................................................... :.......................................... 7 IV-B. WATER MONITORING............................................................................................................. 8 IV-C. DIRECT RADIATION MONITORING....................................................................................... 8 V.
REFERENCES..................................................................................................................................... 10 VI.
APPENDICES..................................................................................................................................... 11 APPENDIX A: LAND USE CENSUS RESULTS............................................................................... 12 APPENDIX B: SAMPLE SITE DESCRIPTIONS AND MAPS........................................................... 13 APPENDIX C: QUALITY CONTROL SAMPLE ANALYSIS RESULTS............................................ 18 APPENDIX D: SAMPLE COLLECTION AND ANALYSIS METHODS............................................. 20 APPENDIX E: ENVIRONMENTAL MONITORING PROGRAM DESIGN........................................ 21 APPENDIX F: 2020 SAMPLE ANALYSIS RAW DATA TABLES..................................................... 26 APPENDIX G: 2020 MISSED SAMPLE REPORT........................................................................... 27 Rancho Seco ISFSI 2
2020AREOR
LIST OF FIGURES FIGURE TITLE PAGE FIGURE B-1 RADIOLOGICAL ENVIRONMENTAL SAMPLING LOCATIONS ON AND NEAR THE SITE--------------*---
15 FIGURE B-2 RADIOLOGICAL ENVIRONMENTAL CONTROL LOCATIONS DI ST ANT FROM THE SITE------------------------------------------------------------- 16 Rancho Seco ISFSI 3
2020AREOR
TABLE LIST OF TABLES TITLE PAGE 1
ENVIRONMENTAL RADIOLOGICAL MONITORING PROGRAM ANNUAL
SUMMARY
9 B-1 RADIOLOGICAL ENVIRONMENTAL MONITORING SITES AND MAP LOCATIONS 17 F-1 2020 LUXEL BADGE
SUMMARY
{DIRECT RADIATION) 26 Rancho Seco ISFSI 4
2020AREOR
2020 ANNUAL RADIOLOGICAL ENVIRONMENTAL OPERATING REPORT I.
EXECUTIVE
SUMMARY
This report contains results from the Radiological Environmental Monitoring Program (REMP) for the Rancho Seco Independent Spent Fuel Storage Installation (ISFSI) compiled for the period January 1, 2020 through December 31, 2020. This program is conducted by Sacramento Municipal Utility District (SMUD) staff in accordance with the REMP Manual. This report is compiled and submitted in accordance with the Rancho Seco Quality Manual, Appendix A, Section 1.5.2.2 [RS01 ].
The results of the 2020 Radiological Environmental Monitoring Program showed that operations at the Rancho Seco ISFSI had no significant radiological impact on the environment.
Phase I radiological dismantlement of the nuclear facility was completed in December 2008 and the release of the Rancho Seco property, except for the area associated with the Interim Onsite Storage Building (IOSB), from NRC license DPR-54 was approved on September 25, 2009.
Phase II decommissioning activities, including the performance of Final Site Status Surveys, were performed in 2016 and early 2017. The NRC terminated the Part 50 license on August 31,
'2018.
The remaining licensed area at the site consists of the approximately 14-acre Independent Spent Fuel Storage Installation licensed under 10 CFR Part 72 for the storage of used nuclear fuel.
In accordance with the current site status, the REMP Manual reflects that the only normal remaining pathway to impact a member of the public at the Rancho Seco ISFSI is the direct radiation pathway.
During the reporting period, the environs adjacent to the Rancho Seco ISFSI were monitored using Luxel monitoring badges. Doses resulting from ambient exposure to terrestrial and atmospheric direct radiation sources were measured through the placement and retrieval of Luxe! monitoring badges. Direct radiation measurements attributable to ISFSI operations, based on control and indicator locations and review of historical data, ranged from indistinguishable above background levels to slightly elevated levels (approximately 1-2x BKGD).
II.
LAND USE CENSUS With the completion of Phase I of Radiological Decommissioning in 2008, the requirement to perform a Land Use Census was removed as a required program from the Rancho Seco Quality Manual (RSQM).
Ill.
RADIOLOGICAL IMPACT EVALUATION PREDICTED POTENTIAL RADIOLOGICAL IMPACT Rancho Seco ISFSI 5
2020AREOR
Gaseous Effluent Exposure Pathways No gaseous effluent releases were conducted in 2020; therefore, no dose calculations were performed.
Liquid Effluent Exposure Pathways The onsite liquid effluent pathway and any potential source of liquid effluents were removed during the decommissioning process; therefore, there were no liquid effluent releases conducted nor dose calculations performed for 2020.
FUEL CYCLE DOSE EVALUATION REMP Manual section 8.1.4 requires each Annual Radiological Environmental Operating Report (AREOR) to include information related to REMP Manual section 5.0, Fuel Cycle Dose. The Fuel Cycle Dose Specification limits the annual dose or dose commitment to any real member of the public to 25 mrem to the total body or any organ, except the thyroid which is limited to 75 mrem.
This specification implements requirements promulgated by the United States Environmental Protection Agency [CFRa].
Consistent with REMP Manual section 5.0, no fuel cycle dose evaluation was required to be performed during 2020 since no REMP measurement exceeded the established reporting levels.
Additionally, with no liquid or gaseous effluent releases, effluent dose predictions did not exceed twice the dose guidelines of 10 CFR Part 50, Appendix I [CFRb]. Therefore, Appendix I guidelines for radioactive effluents were not exceeded and determination of an actual dose commitment delivered to a real member of the public was not required.
Analysis of the Luxel measurements taken at the perimeter of the facility (fence boundaries beyond which public access is not normally controlled) indicate that in no case could a real member of the public have received more than 25 mrem during 2020, indicating compliance with 10 CFR 72.104.
Rancho Seco ISFSI 6
2020AREOR
OBSERVED POTENTIAL RADIOLOGICAL IMPACT Gaseous Effluent Exposure Pathways No routine gaseous effluent pathways remain in the current site configuration. No gaseous effluents were released in 2020; therefore, no dose calculations were performed.
Liquid Effluent Exposure Pathways All liquid effluent pathways have been decommissioned at Rancho Seco. The REMP Manual was revised to delete all liquid exposure pathway sample locations in reflection of current site conditions, therefore, no dose calculations were completed for 2020.
Direct Radiation Exposure Pathway Based on Luxel control and indicator locations, and a review of historical data, the ISFSI did not contribute a significant component to the recorded direct gamma radiation field. The current year's data shows that there is little measurable direct radiation effect on the environment. Since the ISFSI is in a static materials storage condition and there are minimal direct radiation measurements of the surrounding environment, the conclusion remains that the ISFSI has no significant direct radiation effect on the environment. This is the same conclusion that has been made since the fuel was placed into the ISFSI in 2002.
Luxel badge locations around the ISFSI security fence indicated higher readings, attributed to the fuel stored in the ISFSI, and are within design calculations. This monitoring is outside of the REMP and therefore the results of this monitoring are not included in this report.
IV.
PROGRAM ANALYSIS RESULTS
SUMMARY
This section compiles Program data with corresponding evaluations. Each of the following subsections presents information about each of the principal environmental exposure pathways monitored by the Program:
Direct Radiation (Section IV-C)
Table 1 is a comprehensive data summary presented in a format considered acceptable by the US Nuclear Regulatory Commission. Information contained in Table 1 was derived from data presented in Appendix F.
IV-A. ATMOSPHERIC MONITORING DATA EVALUATION The REMP Manual was revised in January 2010 to delete all sample locations except for the Luxel direct radiation monitoring badges. No atmospheric monitoring data was collected.
Rancho Seco ISFSI 7
2020AREOR
IV-8. WATER MONITORING DATA EVALUATION The REMP Manual Was revised in January 2010 to delete all sample locations except for the Luxel direct radiation monitoring badges. No water monitoring data was collected.
IV-C. DIRECT RADIATION MONITORING DATA EVALUATION The revision to the REMP Manual conducted in 201 O eliminated some locations where dose monitoring was performed to reflect the current status of the licensed facility as discussed above. During 2010, and again in 2011, the locations eliminated from the REMP continued to be monitored. Beginning in 2012, only the locations requiring monitoring by the REMP are being monitored. Comparisons of historical data on a year-to-year basis have been provided in previous reports. Because the environmental impact is so low, such comparisons will no longer be reported.
In addition to the Control Locations utilized for comparison purposes, Quality Control Luxels are included throughout the process to account for variables like dose received during shipment.
Luxel data for indicator and control locations during 2020 ranged from 3 to 12 mrem per quarter; with an average of 8.2 mrem. This confirms that there continues to be no significant observable direct radiation component due to ISFSI operations (i.e., storage or utilization of licensed radioactive material within the restricted area).
The summary data for 2020 direct radiation monitoring is presented in Table 1. Comprehensive data tables are given in Appendix F, Table F-1.
Rancho Seco ISFSI 8
2020AREOR
Medium or Pathway Sampled (Unit of Measurement)
Direct Radiation (mrem/qtr.)
TABLE 1 ENVIRONMENTAL RADIOLOGICAL MONITORING PROGRAM ANNUAL
SUMMARY
Name of Facility Rancho Seco ISFSI Docket No.72-011 Location of Facility Sacramento, California (County, State)
Type and Lower All Indicator Total Limit of Locations Number of Detection Mean (f)a Analysis (LLD)
Range Performed Luxel 8.7 (48/48) 56 1 mrem/qtr (6-12)
. Reporting Period January - December 2020 Location with Highest Annual Control locations Mean Mean (f) a Name Mean (f} a Range Distance Range
& Direction RTL0.5 NP 10.8 (8/8) 4.9 (8/8) 0.5 miles 281 ° (8-12)
(3-7)
RTL0.2 NP 9.8 (8/8) 0.2 miles 280° (8-12) a Mean and Range based upon detectable measurements only. Fraction of detectable measurements at specified locations is indicated in parentheses. (f)
Rancho Seco ISFSI 9
2020AREOR Number of Non-routine Reported Measurements 0
V.
REFERENCES CFRa CFRb NRC79a NRC79b NUREG79 NUREG80a RS01 Rancho Seco ISFSI Code of Federal Regulations, "Environmental Radiation Protection Standards for Nuclear Power Operations," Title 40, Part 190.
Code of Federal Regulations, "Domestic Licensing of Production and Utilization Facilities," Title 10, Part 50.
United States Nuclear Regulatory Commission, 1979, "An Acceptable Radiological Environmental Monitoring Program," Branch Technical Position, Revision 1.
United States Nuclear Regulatory Commission, 1979, "Quality Assurance for Radiological Monitoring Programs (Normal Operations) - Effluent Streams and the Environment," Regulatory Guide 4.15, Revision 2.
United States Nuclear Regulatory Commission, 1979, "Radiological Effluent Technical Specifications for PWRs," NUREG-0472, Revision 2.
United States Nuclear Regulatory Commission, 1980, "Methods for Demonstrating LWR Compliance with the EPA Uranium Fuel Cycle Standard (40 CFR Part 190)," NUREG-0543.
RSLBD-010, Rancho Seco Quality Control Manual, Appendix A 10 2020AREOR
VI.
APPENDICES Rancho Seco ISFSI 11 2020AREOR
APPENDIX A: LAND USE CENSUS RES UL TS With the revision of the REMP Manual in January 2010, the requirement to complete a Land Use Census has been deleted.
Rancho Seco ISFSI 12 2020AREOR
APPENDIX B: SAMPLE SITE DESCRIPTIONS AND MAPS This appendix provides descriptive information about the sampling locations and maps of all the locations for the Radiological Environmental Monitoring Program sites.
Table B-1 provides information on sample type, identification codes, and map location references.
The sample identification code is an alphanumeric string beginning with the prefix "R" (for Rancho Seco ISFSI) followed by two letters to identify the sample media:
TL Direct Gamma Radiation (Luxel)
The numeric designations, which follow the letter designations, indicate the straight-line distance (in miles) from the center of the Reactor Building to the monitoring site.
The next letter designates the sector in which the monitoring location is located. The letters A through R are used for sector designators. The letters I and O are not used to prevent confusion with the numbers one and zero in the ID codes.
Sector Letter Degrees Azimuth Compass Point A
348.75 to 11.25 N
B 11.25 to 33.75 NNE C
- 33. 75 to 56.25 NE D
56.25 to 78. 75 ENE E
- 78. 75 to 101.25 E
F 101.25 to 123.75 ESE G
123.75 to 146.25 SE H
146.25 to 168.75 SSE J
168.75 to 191.25 s
K 191.25 to 213.75 SSW L
213.75 to 236.25 SW M
236.25 to 258.75 WSW N
258.75 to 281.25 w
p 281.25 to 303. 75 WNW Q
303.75 to 326.25 NW R
326.25 to 348. 75 NNW The final letter designation indicates if the location is part of the operational REMP program ("O")
or post-operational REMP program ("P").
Rancho Seco ISFSI 13 2020AREOR
Table 8-1 Figure 8-1 Lists each location referencing the sample type and the location ID code to the map site number on one of the four Radiological Environmental Monitoring Site Maps included in this Appendix.
Site Location Map:
Shows the locations of the sample locations near the Site.
Figure 8-2 Distant Locations Map: Control locations away from the site are shown on this map.
Map Key O ~
Location that requires monitoring per REMP Rancho Seco ISFSI 14 2020AREOR
Figure B-1 Radiological Environmental Sampling Locations on and near the Site Rancho Seco ISFSI 15 2020AREOR
Figure 8-2 Radiological Environmental Control Locations Rancho Seco ISFSI 16 2020AREOR
Table B-1 Radiological Environmental Monitoring Sites and Map Locations Sample Type ID Code Class Map Collection Description. of Location Miles Sector Location No.
Freauencv LUXEL RTL1.7FO CON.
43 Quarterly Well pump fence @ reservoir 1.7 G
LUXEL RTL 1.8FO CON.
19 Quarterly Rancho Seco Lake Maintenance Building 1.8 F
LUXEL RTL0.3PO IND.
68 Quarterly West Perimeter Fence, West of IOSB 0.3 p
LUXEL RTL0.3NP IND.
88 Quarterly South ISFSI 1 00m Fence 0.3 N
LUXEL RTL0.4NP IND.
89 Quarterly Southwest Comer ISFSI 100 m Fence 0.4 N
LUXEL RTL0.5NP IND.
90 Quarterly Northwest ISFSI 100 m Fence 0.5 p
LUXEL RTL0.3QP IND.
91 Quarterly North Perimeter Fence/Pole UD034403*
0.3 Q
LUXEL RTL0.4PP IND.
94 Quarterly North ISFSI 100 m Fence 0.4 p
LUXEL RTL0.2PP IND.
95 Quarterly Well East of IOSB 0.2 p
LUXEL RTL0.2NP IND.
96 Quarterly IOSB Electrical Transformer, SE comer 0.2 p
LUXEL RTL0.3NP IND.
97 Quarterly IOSB west roof access ladder 0.3 p
LUXEL RTL0.2NP IND.
98 Quarterly Switchyard Fence north side 0.2 N
LUXEL RTL0.3NP IND.
99 Quarterly ISFSI 100 meter fence, vehicle access qate 0.3 N
LUXEL RTL0.3NP IND.
100 Quarterly West Perimeter Fence, NW of IOSB 0.3 N
Note: Prior to the 2010 Report, the "Map Location No." used here was different than the "Location Number" used in Table F-1. To prevent confusion, the same numbering system is now used throughout the report.
- The monitoring badge at Map Location No. 91 was moved approximately 30 feet southwest on November 20, 2018 to support removal of unnecessary fencing. The badge was moved from the fence to utility pole UD034403.
Rancho Seco ISFSI 17 2020AREOR
APPENDIX C: QUALITY CONTROL SAMPLE ANALYSIS RESULTS QUALITY ASSURANCE AND CONTROL Implementation of the Radiological Environmental Monitoring Program (REMP) consists of a number of discrete steps including:
Sample collection, Packaging, Shipment and receipt, Measurements of radioactivity, Data evaluation, and Reporting.
These program elements are performed according to approved, written procedures to assure the validity of REMP results.
Because REMP measurement validity is important for evaluating protection of the health and safety of the public, the Rancho Seco ISFSI has established an Environmental Quality Assurance Program (EQAP) for radiological environmental measurements. The Environmental QA Program implements the guidance provided in Regulatory Guide 4.15, [NRC79b].
INTERLABORA TORY COMPARISON PROGRAM With the revision of the REMP Manual to delete all sample locations except for Direct Radiation monitoring locations, no discussion of lnterlaboratory Comparison or analysis of laboratory Quality Assurance program is necessary.
RANCHO SECO AUDIT AND SURVEILLANCE RESULTS The Rancho Seco Quality Program requires periodic audits of REMP activities. Audits are performed by an independent Quality Assurance audit company.
Rancho Seco ISFSI 18 2020AREOR
DIRECT RADIATION {Luxel) COMPARISON PROGRAM Landauer maintains NVLAP certification with NIST. A review of Landauer's NVLAP certific.ation results indicates that Landauer has satisfactorily completed all the required tests for the types of environmental radiation monitored at the Rancho Seco ISFSI and is certified through December 31, 2021. NVLAP certification is considered to satisfy the interlaboratory comparison requirements for the direct radiation measurement devices.
This comparison program satisfies the requirement of the REMP Manual section 6.0.
Rancho Seco ISFSI 19 2020AREOR
APPENDIX D: SAMPLE COLLECTION AND ANALYSIS METHODS For each of the sample media collected, the method of collection is documented in Rancho Seco ISFSI procedures. A brief description of these collection and analysis methods is included in this Appendix.
Sample Media DIRECT RADIATION Rancho Seco ISFSI Collection/Analysis Method Monitoring badges, (Luxels), are located within a two (2) mile radius of the site. The badges within a one (1) mile radius are considered indicator badges. Two (2) badges are placed at each monitoring location to assure adequate data recovery and to improve measurement statistics. The badge field exposure cycle is approximately ninety (90) days. At the end of the field exposure cycle, the badges ~re exchanged and returned to the contract laboratory for processing.
20 2020AREOR
APPENDIX E: ENVIRONMENTAL MONITORING PROGRAM DESIGN PROGRAM BASIS The Sacramento Municipal Utility District conducts a continuous Radiological Environmental Monitoring Program (REMP) at the Rancho Seco ISFSI to assess the impact of ISFSI operation on the surrounding environment. The current Post-Operational REMP has been revised to reflect the requirements of the ISFSI Technical Specifications for direct radiation monitoring.
During 2020, the program was directed and executed by the Manager, Rancho Seco Assets, who has primary accountability.
The Program is designed consistent with Title 10, Code of Federal Regulations, Part 50, Appendix I - Section IV, B.2, B.3 and C, and Appendix A, "General Design Criteria for Nuclear Power Plants," Criterion 64. The program also complies with Title 10, Code of Federal Regulations, Part 20, "Standards for Protection Against Radiation," Section 1302. These federal requirements are cited in the Rancho Seco Quality Manual, Appendix A, and the REMP Manual. REMP requirements are implemented through the review, approval and routine use of several documents, namely the REMP Manual, Surveillance Procedures and Health Physics Implementing Procedures.
The programmatic elements of the REMP are based on regulatory requirements and associated guidelines. The objectives of the Program are to:
- 1.
Provide the technological basis and the instruction for monitoring the environs for radioactivity sources. The radioactive sources, which contribute to detectable radioactivity in the local environs, are comprised of:
Naturally occurring background, Direct radiation from materials storage, World-wide weapons testing, and Major global nuclear accidents
- 2.
Provide quantitative measurements in the direct radiation exposure pathway.
- 3.
Provide indications of the largest potential radiation exposure for individuals because of radionuclides in the principal exposure pathways.
The Program is developed and conducted using recognized standards and practices NRC79a, NRC79b, NUREG79, and NUREG80a.
Rancho Seco ISFSI 21 2020AREOR
REMP CHANGES The REMP Manual. and sampling program was revised during 2010 to delete all sample locations except for the direct radiation pathway. The requirement for a Land Use Census and conducting an ICP for the radioactivity analysis laboratory was also deleted.
No revisions to the REMP Manual have occurred since that revision.
EXPOSURE PATHWAYS The fundamental parameters, which have been defined prior to monitoring the environs, are:
- 1.
Identification of the effluent release pathways
- 2.
Identification of the human exposure pathways Each of these parameters is discussed below.
Effluent Release Pathways The principal pathways which may result in human exposure to radiation and radioactive material originating from Station operation are direct radiation from onsite sources. Gaseous and liquid effluents are not currently being discharged or monitored.
Direct Radiation In the direct radiation pathway, potential radiation exposure may occur from radioactive material storage areas, which are contained within the facility perimeter.
MONITORING LOCATION SELECTION The required monitoring sites are listed in the REMP Manual, Table 3. This program is supplemented with additional samples to compensate for changes in the radiological environment surrounding the Rancho Seco ISFSI. Indicator sites are placed in areas which would be most sensitive to the effects of ISFSI operations. If radioactive material is detected above background at any of these indicator sites, observed potential exposure and dose to humans can be estimated to verify the effectiveness of the REMP in monitoring potential exposures or doses.
Control locations provide data that should not be influenced by the operations of the Rancho Seco ISFSI. These locations are selected based upon distance from the ISFSI. Samples obtained from control locations should, upon analysis, reveal information about the presence and distribution of naturally occurring and man-made radioactive materials. Data from these locations are used to.aid in the discrimination between the effects of Rancho Seco direct radiation sources
- and other natural phenomena or accidental releases, which may result in human exposure.
The direct radiation pathway is monitored through a network of monitoring badges at sites distributed in sectors centered on the facility. The badges are located primarily at the site around the ISFSI. This design provides the capability to easily detect ISFSl-induced direct radiation contributions to the observed terrestrial and cosmic direct radiation background.
Rancho Seco ISFSI 22 2020 AREOR
Some badges have been sited in locations to record direct radiation to provide 10 CFR Part 72 license required data for the Independent Spent Fuel Storage Installation (ISFSI).
Appendix B contains a detailed description and illustration of the REMP sample and monitoring locations.
SAMPLE MEDIA Samples are collected from predetermined monitoring sites at a specified frequency. The sample media chosen is a function of the type of monitoring desired and coincides with one of the following exposure pathways:
o Direct radiation Direct radiation monitoring is achieved by placing monitoring badges at aboveground sites.
The monitoring badges respond to, and record the amount of, gamma radiation exposure. The source of this gamma radiation exposure is varied and includes potential ISFSI effluents, naturally occurring terrestrial, and cosmogenic radionuclides. The monitoring badges are also influenced by seasonal and global (fallout) radiation sources.
There are 14 sites that require monitoring per the REMP, which are within a 2-mile radius of the Rancho Seco ISFSI. The monitoring badges are placed at the Rancho Seco Industrial Area Boundary, at the ISFSI and IOS8, and at control locations located beyond one mile of the Station.
SAMPLE ANALYSIS & DA TA HANDLING Data comparisons are made between individual control and indicator sample sites to isolate potential ISFSI influences on the measurement results. Quality Control dosimeters stored in a shielded storage location during the measurement period but kept with the dosimeters during shipping and storage measure non-environmental doses and this amount is subtracted from the total measurements at the monitoring and control locations.
The summarized results of the 2020 Radiological Environmental Monitoring Program are presented in Table 1.
Individual (raw data) results are presented in Appendix F, Table F-1.
Rancho Seco ISFSI 23 2020 AREOR
REGULATORY REPORTING LEVELS Sample analysis data is reviewed and evaluated by the Staff as the results are received. All sample analysis results are reviewed for correct sensitivity and anomalies.
Activity concentration values are used to determine the environmental Fuel Cycle Dose quantities that, if exceeded, require a Special Report to be submitted to the USN RC. In accordance with the REMP Manual (Section 5, Fuel Cycle Dose), the Special Report must include an evaluation of any release conditions, environmental factors, or other aspects, which caused the reporting limits to be exceeded.
In addition to the Fuel Cycle Dose reporting requirements, a Special Report is required to be submitted to the USNRC when more than one radionuclide is detected in the sampling medium and the summed ratio of detected activity concentration to the respective Reporting Level concentration is greater than, or equal to, unity (1 ). When radionuclides are detected which are a result of ISFSI effluents, a Special Report is required to be submitted if the potential annual dose commitment exceeds the 10 CFR 50, Appendix I guidelines.
No reports of the types described above were required to be submitted during 2020.
SENSITIVITY OF THE REMP MEASUREMENT PROCESS All Program measurements must be performed at a sensitivity, which meets USNRC requirements. This sensitivity is determined "before the fact" (a prion) for each radionuclide of interest and sample analysis type. Typical controllable sensitivity parameters include:
Sample volume or mass Sampling efficiency Time from sample collection to measurement Instrument detection efficiency for the nuclides (energies) of interest Background radiation levels Chemical recovery factors By adjusting and controlling each of these parameters to maximize measurement process efficiency, a maximum sensitivity level (activity concentration) can be specified for each nuclide of interest and analysis type while maintaining an economic measurement process. The maximum sensitivities in the REMP are specified by the USNRC in the REMP Manual approved for Rancho Seco. These sensitivities are referred to as "LLD's", an acronym for "Lower Limit of Detection".
LLD's are specified on an "a priori" basis and apply to routine measurement process capabilities when no other interfering radioactivity is present. The word "routine" is emphasized since occasional circumstances, such as limited sample mass, elevated levels of background radiation and interfering nuclides can contribute to sensitivity degradation.
Such occurrences are normally noted and reported during the conduct of REMP activities.
Rancho Seco ISFSI 24 2020 AREOR
Meeting the LLD requirements is a quality control function shared by both REMP and the analytical laboratory personnel. Once the laboratory establishes values for the controllable parameters for each analysis type, sample chain of custody controls ensure that these parameters are upheld. If all parameters are upheld, then compliance with the LLD requirements has been demonstrated. No specific LLD values for Program measurements are included in this report as no applicable monitoring was performed.
Since most of the samples analyzed result in the detection decision "activity not identified", a Minimum Detectable Activity (MDA) concentration value is calculated and reported. This value can be thought of as the LLD-at-the-time-of-counting since it is calculated using an equation which is similar to the one used to establish LLD parameters. The biggest difference is that actual (not "a prior,") parameters are used, including interference from natural radioactive material in the sample. It is important to note that MDA's are reported only for those measurements where the "activity not identified" decision has already been made.
MDA values are used primarily to identify changes in the measurement process and to convey more information about the measurement itself. Without the use of the MDA concept, most Program measurements would be reported simply as "<LLD". With MDA used, Program measurements are reported as"< xxx "where "xxx" is the calculated MDA concentration.
With the revision of the REMP Manual to delete all exposure pathways except for direct radiation, these sensitivities are no longer applicable to the current monitoring program.
Rancho Seco ISFSI 25 2020AREOR
APPENDIX F: 2020 SAMPLE ANALYSIS RAW DATA TABLES TABLE F-1 2020 Luxel Badge Summary (Direct Radiation)
Quarterly (mrem)
Location ID Description Type 2020-1 2020-2 Number 19 43 68 88 89 90 91 94 95 96 97 98 99 100 RTL 1.8FO RS Lake Maintenance Building RTL 1.7FO RS Lake Well Enclosure RTL0.3PO Site fence west by ISOB RTL0.3NP ISFSI south fence RTL0.4NP ISFSI south fence RTL0.5NP ISFSI west fence RTL0.3QP Site fence NW corner RTL0.4PP ISFSI fence north RTL0.2PP IOSBWell RTL0.2NP IOSB Electrical Transformer RTL0.3NP IOSB Roof Access Ladder RTL0.2NP Switchyard Fence RTL0.3NP 100 Meter Fence RTL0.3NP Access Road NW of IOSB Minimal Reporting Dose is 1 mrem.
I = Indicator Location / C = Control Location M = Missing Data, see Appendix G Rancho Seco ISFSI 26 C
6 4
C 6
6 8
8 9
10 8
8 10 12 9
7 10 10 10 10 10 10 9
8 8
7 10 10 8
8 2020-3 2020-4 4
5 5
6 8
8 9
9 7
8 10 12 7
8 10 9
9 10 10 10 8
7 7
8 10 10 8
9 2020AREOR
APPENDIX G: 2020 MISSED SAMPLE REPORT In accordance with the requirements REMP Manual section 3.1, the following samples are being reported as not being collected for the reasons indicated. Corrective action as required by the REMP Manual is as indicated.
Direct Monitoring Pathway (Luxel Badge)
No Luxel badges were missing from their locations in 2020.
Rancho Seco ISFSI 27 2020AREOR