ML25041A189
| ML25041A189 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 12/31/2024 |
| From: | Wiblin C ADP CR3 |
| To: | Office of Nuclear Material Safety and Safeguards, Document Control Desk |
| Shared Package | |
| ML25041A177 | List: |
| References | |
| 3F0225-01 | |
| Download: ML25041A189 (1) | |
Text
ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 ADP CR3, LLC DOCKET NUMBER 50-302 / DOCKET NUMBER 72-1035 LICENSE NUMBER DPR - 72 ATTACHMENT 9 TBD - Basis for No Contaminated Water Dose at CR3 3F0225-01 / Attachment 9 A1
ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 Crystal River 3 Nuclear Power Plant - Technical Basis Document Basis for No Contaminated Water Dose at CR3 Revision 0 December 2024 Prepared by: _____________________________
December 15, 2024___
Claude Wiblin, CHP Date Chesapeake Nuclear Services, Inc.
Reviewed by: _____________________________
_December 15, 2024__
J. Stewart, Bland, CHP Date Chesapeake Nuclear Services, Inc.
Approved by: ____________________________
L. Bryant Atkins, RPM Date December 16,2024 3F0225-01 / Attachment 9 / Page 1 of 10
ADP CR3, LLC 15760 West Power Line Street l Crystal River, FL 34428 i
Contents 1.0 Introduction............................................................................................................ 1 2.0 Groundwater Modeling............................................................................................. 1 3.0 Waterborne Pathway Dose Assessment.................................................................... 1 3.1 Insigni"cant Pathways and Radionuclide Dose Contributors.................................. 1 3.2 Saturated Zone Hydraulic Conductivity................................................................. 3 4.0 Conclusions............................................................................................................ 7 5.0 References.............................................................................................................. 8 Tables Table 1 Peak Dose DCGLs and Time for 1E+05 and 100 m/y Saturated Zone Hydraulic Conductivities for 0.15 m Depth......................................................................... 5 Table 2 Peak Dose DCGLs and Time for 1E+05 and 100 m/y Saturated Zone Hydraulic Conductivities for 1 m Depth.............................................................................. 6 3F0225-01 / Attachment 9 / Page 2 of 10 A1
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Basis for No Contaminated Water Dose at CR3 1.0 Introduction The evaluation of the exposure scenarios and pathways of exposure for Crystal Rives 3 License Termination Plan determined that the groundwater was not usable as a source of drinking water or other waterborne pathways, such as irrigation. This determination was based on several factors, including salinity; the primary factor was that based on State of Florida regulations, a well and groundwater extraction would not be permitted [H&A, 2024b]. However, since the elimination of the waterborne pathways was founded, in part, on a regulatory constraint (restriction on permitting a well and extraction), there was concern that this restriction could be changed in the future. The feasibility of this changing in the future is considered unlikely due to groundwater characteristics. However, to determine the relative dose signi"cance of the groundwater pathways, an evaluation of the waterborne pathways of exposures was performed using the RESRAD-ONSITE V7.02 code.
This TSD calculates the potential doses to an average member of the critical group from waterborne pathways over 1,000 years post license termination.
2.0 Groundwater Modeling CR3 through contractor, Haley & Aldrich, Inc., (H&A) assessed the feasibility of the groundwater pathway [H&A, 2024b]. Based on H&A modeling, if a well were to be installed, saltwater intrusion would impact the well as soon as 1,000 days for the resident farmer and at approximately 6,000 days for a single dwelling using the RESRAD default extraction rates.
This intrusion would not only limit the uses for the Residential Farmer scenario, but the estimated water use or withdrawal does not meet the reasonable assurance criteria required to obtain a water use permit from the Southwest Florida Water Management Division. The model predicts intrusion would negatively impact the aquifer and therefore the permit would be denied. For the foreseeable future, regulatory restrictions nullify the matter (H&A, 2024b).
3.0 Waterborne Pathway Dose Assessment 3.1 Insigni"cant Pathways and Radionuclide Dose Contributors The waterborne pathway requires migration of plant-related radionuclides through the topsoil to the saturated zone and then the contaminated groundwater pumped from a well to reach the pathways of exposure through drinking water and irrigation.
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The dose signi"cance of this migration needs examination, relative to the probable exposure scenarios as evaluated in the LTP for the Resident Farmer. Pathway may be considered insigni"cant if they are less than 10% contributors, collectively. The NRC addresses its de"nition and requirements for insigni"cance in NUREG-1757, Vol. 2, page 3-4:
The NRC staff considers radionuclides and exposure pathways that contribute no more than10 percent of the dose criteria, considering uncertainty1, to be insigni"cant contributors to dose. Because the dose criteria are performance criteria, this 10-percent limit is an aggregate limitation only. That is, the sum of the dose contributions from all radionuclides and pathways considered insigni"cant should be no more than 10 percent of the dose criteria (e.g., no more than 0.025 mSv/y (2.5 mrem/y) for the unrestricted release limit of 0.25 mSv/y (25 mrem/y)). No limitation on either single radionuclides or individual pathways is necessary. In cases of restricted release, where two dose criteria apply (one for institutional controls in place and one that considers the possibility of restrictions failing), the 10-percent limitation should be met for both dose criteria. In making a determination that radionuclides or pathways are insigni"cant, licensees should consider both reasonably foreseeable and less likely but plausible exposure scenarios (see Section 5 for more information). Licensees should also consider the presence of elevated areas, and potential in-growth of progeny from postulated insigni"cant radionuclides, when determining that the radionuclides or pathways contribute no more than 10 percent of the dose criteria and are, therefore, insigni"cant.
With footnote:
1 Uncertainty in exposure scenarios is considered through evaluation of both reasonably foreseeable and less likely but plausible scenarios. Uncertainty in parameter values can be managed through conservative assumptions (e.g., selection of parameter values from parameter distributions that tend to lead to higher doses). Chapter 5, Appendix I and Appendix Q have more information on consideration of uncertainty. (NRC, 2022).
The selection of the Resident Farmer as the average member of the critical group (AMCG), as prescribed in 10 CFR 20.1402, includes all plausible exposure scenarios, certain waterborne pathways have been excluded for the CR3 evaluations. (Refer to LTP Section 6.2 for a detailed discussion on selection of the AMCG for CR3.)
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Both reasonably foreseeable and less likely but plausible exposure scenarios could include waterborne pathways. Results, as evaluated below, showing that the addition of conservatively bounding waterborne pathways would contribute no more than 10% of the total dose for the Resident Farmer provides a basis for exclusion of this less likely but plausible exposure pathway, i.e., additional rationale for elimination of the groundwater pathways from the CR3 DCGL determination. Any perceived water dose, in the future, is insigni"cant.
3.2 Saturated Zone Hydraulic Conductivity Groundwater modeling has shown that the value assumed for the saturated zone hydraulic conductivity is a primary factor affecting the potential contamination levels in groundwater.
Based on site-speci"c modeling, H&A determined that a value of 1 x 105 m/y was representative of site conditions [H&A 2024a]. This value may be considered on the high side of typical environmental values; however, it re"ects the underlying limestone and the tidal in"uence. To bound the scenario, modeling and RESRAD-ONSITE dose calculations have been performed using the site-speci"c value of 1 x 105 m/y, compared with doses using the default value of 100 m/y.
Four different scenarios were evaluated. Two with water pathways active and soil contamination levels at the DCGL values for a 0.15 m depth and a 1 m depth for a top-soil contaminated zone. The other two were for the same conditions but with the water pathways suppressed. This approach allows for a comparison of hypothetical waterborne pathways and doses for the CR3 site, using the H&A modeling versus a very conservative RESRAD default conditions.
NUREG/CR-7267 (NRC, 2020), Default Parameter Values and Distribution in RESRAD-ONSITE V7.2, RESRAD-BUILD V3.5, and RESRAD OFFSITE V4.0 Computer Codes, provides a listing and explanation of modeling input parameters. This NUREG was reviewed for speci"cs on Saturated Zone Hydraulic Conductivity:
- Table 1-1 lists the Saturated Zone Hydraulic Conductivity as a physical parameter with a lognormal distribution.
- Table 2-1 places the RESRAD-ONSITE default value at 100 m/y.
- Table 4-4 list the high correlation with dose for the Resident Farmer Scenario with an intermediate ++ score for the only radionuclide I-129 at with a standardized rank regression coefficient (SRRC) range >0.1 to 0.2; no other radionuclides of the 12 tested (C-14, Co-60, Cs-137, I-129, Np-129, Pu-239, Ra-226, Ra-228, Sr-90, Tc-99, and U-238) were listed. Of the 12, six were CR3 ROCs, including the LTP Chapter 5 identi"ed dose-signi"cant contributors (C-14, Co-60, Sr-90, Cs-137).
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- Table 4-5 indicates that the hydraulic conductivity in the contaminated zone is used along with the water in"ltration rate and soil b parameter to determine the water saturation ratio in soil, which is then used to determine the leach rate of contaminants as well as that saturated zone hydraulic conductivity and hydraulic gradient determine the "ow rate.
- Table 4-13 provides that a faster transport rate allows radionuclides from the far end of the primary contamination to reach the well before the "ow of radionuclides from the near end decreases appreciably.
From the NUREG data, peak times for doses generated with the default parameter of 100 m/y were selected for comparison to peak times for doses generated with the site-speci"c value of 1 x 105 m/y to determine if the parameter were sensitive in dose making times. The factor of a 1,000 difference was deemed sufficient to reveal sensitivity recalling that only I-129 was previously considered sensitive.
For the evaluation, multiple RESRAD-ONSITE runs out to a period of 1,000 years at increments of 0, 1, 3, 10, 30, 100, 300, 1000 years were performed with all parameters the same except for water pathways being set to active with runs for the Saturated Zone Hydraulic Conductivity parameter set at 1 x 105 m/y and for 100 m/y, the RESRAD-ONSITE default. The other parameters are established in Appendix B to LTP Chapter 6, Crystal River Unit 3 RESRAD-Onsite Input Parameter Sensitivity Analysis. Appendix B to LTP Chapter 6 showed that the maximum dose for all ROCs occurs at the license termination date, i.e., within the 1st year after release for unrestricted use. This situation is with waterborne pathways excluded.
Table 1 provides RESRAD-ONSITE results and determined peak dose times for the 0.15 m depth contaminated zone and Table 2 provides the data for a 1 m depth. With RESRAD-ONSITE for 0.15 m and 1 m soil depths, with active water pathways and the Saturated Zone Hydraulic Conductivity parameter value set to both 100 m/y and 1 x 105 m/y, the maximum dose for the 0.15 m depth occurs within the 1st following license termination, except for H-3 and C-14 which occur at 7.5 years and 1.3 years, respectively. At the 1 m depth, there was a maximum time for the Tc-99 dose at 17.2 years; all others were for the 1st year. These times of maximum dose (H-3 at 7.5 years, C-14 at 1.3 years, and Tc-99 at 17.2 years) are all within the 30-years assumed for continued restrictions on groundwater extraction.
For a conservative assumption, it is assumed that the installation of a well would occur at 30 years after unrestricted release of the site. Examining the RESRAD-Onsite calculations, it is shown that at this 30-year time, the waterborne dose contributions for H-3 and C-14 are zero and Tc-99 is close to zero; the more time beyond the peak dose time, the less dose from both water independent and water dependent pathways. The DCGLs for the Resident 3F0225-01 / Attachment 9 / Page 6 of 10 A1
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Farmer in the LTP CH 5 remain conservative. All RESRAD-ONSITE runs (78) are provided in Attachment D.
Table 1 Peak Dose Times and DCGLs for 1E+05 and 100 m/y Saturated Zone Hydraulic Conductivities for 0.15 m Soil Depth ROC Pathways Saturated Zone Hydraulic Conductivity (m/y)
Peak Dose Rate (mrem/pCi/g)
Time of Peak Dose (y)
DCGLSS (pC/g)
Am-241 w H2O 1.00E+05 1.17E-01 0.00E+00 214 w H2O 1.00E+02 1.17E-01 0.00E+00 214 no H2O 1.17E-01 0.00E+00 214 C-14 w H2O 1.00E+05 2.91E-01 1.30E+00 86 w H2O 1.00E+02 2.31E-01 0.00E+00 108 no H2O 2.31E-01 0.00E+00 108 Co-60 w H2O 1.00E+05 6.10E+00 0.00E+00 4.1 w H2O 1.00E+02 6.10E+00 0.00E+00 4.1 no H2O 6.10E+00 0.00E+00 4.1 Cs-137 w H2O 1.00E+05 1.64E+00 0.00E+00 15.2 w H2O 1.00E+02 1.64E+00 0.00E+00 15.2 no H2O 1.64E+00 0.00E+00 15.2 Eu-152 w H2O 1.00E+05 2.81E+00 0.00E+00 8.9 w H2O 1.00E+02 2.81E+00 0.00E+00 8.9 no H2O 2.81E+00 0.00E+00 8.9 Eu-154 w H2O 1.00E+05 3.03E+00 0.00E+00 8.3 w H2O 1.00E+02 3.03E+00 0.00E+00 8.3 no H2O 3.03E+00 0.00E+00 8.3 Fe-55 w H2O 1.00E+05 7.12E-04 0.00E+00 35,100 w H2O 1.00E+02 7.12E-04 0.00E+00 35,100 no H2O 7.12E-04 0.00E+00 35,100 H-3 w H2O 1.00E+05 7.04E-04 0.00E+00 35,500 w H2O 1.00E+02 9.37E-04 7.45E+00 26,678 no H2O 7.04E-04 0.00E+00 35,500 Ni-59 w H2O 1.00E+05 2.11E-03 0.00E+00 11,800 w H2O 1.00E+02 2.11E-03 0.00E+00 11,800 no H2O 2.11E-03 0.00E+00 11,800 Ni-63 w H2O 1.00E+05 5.78E-03 0.00E+00 4,300 w H2O 1.00E+02 5.78E-03 0.00E+00 4,300 no H2O 5.78E-03 0.00E+00 4,300 Pu-239 w H2O 1.00E+05 1.14E-01 0.00E+00 219 w H2O 1.00E+02 1.14E-01 0.00E+00 219 no H2O 1.14E-01 0.00E+00 219 Sr-90 w H2O 1.00E+05 1.07E+00 0.00E+00 23.4 w H2O 1.00E+02 1.07E+00 0.00E+00 23.4 no H2O 1.07E+00 0.00E+00 23.4 Tc-99 w H2O 1.00E+05 1.97E-02 0.00E+00 1,260 w H2O 1.00E+02 1.97E-02 0.00E+00 1,260 no H2O 1.97E-02 0.00E+00 1,260 3F0225-01 / Attachment 9 / Page 7 of 10 A1 I
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Table 2 Peak Dose Times and DCGLs for 1E+05 and 100 m/y Saturated Zone Hydraulic Conductivities for 1 m Soil Depth ROC Pathways Saturated Zone Hydraulic Conductivity (m/y)
Peak Dose Rate (mrem/pCi/g)
Time of Peak Dose (y)
DCGLVS (pC/g)
Am-241 w H2O 1.00E+05 2.86E-01 0.00E+00 87.4 w H2O 1.00E+02 2.86E-01 0.00E+00 87.4 no H2O 2.86E-01 0.00E+00 87.4 C-14 w H2O 1.00E+05 1.52E+00 0.00E+00 16.4 w H2O 1.00E+02 1.52E+00 0.00E+00 16.4 no H2O 1.52E+00 0.00E+00 16.4 Co-60 w H2O 1.00E+05 7.20E+00 0.00E+00 3.4 w H2O 1.00E+02 7.20E+00 0.00E+00 3.4 no H2O 7.20E+00 0.00E+00 3.4 Cs-137 w H2O 1.00E+05 2.60E+00 0.00E+00 9.6 w H2O 1.00E+02 2.60E+00 0.00E+00 9.6 no H2O 2.60E+00 0.00E+00 9.6 Eu-152 w H2O 1.00E+05 3.18E+00 0.00E+00 7.8 w H2O 1.00E+02 3.18E+00 0.00E+00 7.8 no H2O 3.18E+00 0.00E+00 7.8 Eu-154 w H2O 1.00E+05 3.44E+00 0.00E+00 7.2 w H2O 1.00E+02 3.44E+00 0.00E+00 7.2 no H2O 3.44E+00 0.00E+00 7.2 Fe-55 w H2O 1.00E+05 7.43E-04 0.00E+00 33,600 w H2O 1.00E+02 7.43E-04 0.00E+00 33,600 no H2O 7.43E-04 0.00E+00 33,600 H-3 w H2O 1.00E+05 1.68E-02 0.00E+00 1,480 w H2O 1.00E+02 1.68E-02 0.00E+00 1,480 no H2O 1.68E-02 0.00E+00 1,480 Ni-59 w H2O 1.00E+05 9.31E-03 0.00E+00 2,685 w H2O 1.00E+02 9.31E-03 0.00E+00 2,685 no H2O 9.31E-03 0.00E+00 2,685 Ni-63 w H2O 1.00E+05 2.55E-02 0.00E+00 980 w H2O 1.00E+02 2.55E-02 0.00E+00 980 no H2O 2.55E-02 0.00E+00 980 Pu-239 w H2O 1.00E+05 4.23E-01 0.00E+00 59 w H2O 1.00E+02 4.23E-01 0.00E+00 59 no H2O 4.23E-01 0.00E+00 59 Sr-90 w H2O 1.00E+05 6.94E+00 0.00E+00 3.6 w H2O 1.00E+02 6.94E+00 0.00E+00 3.6 no H2O 6.94E+00 0.00E+00 3.6 Tc-99 w H2O 1.00E+05 4.04E-01 0.00E+00 61.8 w H2O 1.00E+02 4.90E-01 1.72E+01 51.0 no H2O 4.04E-01 0.00E+00 61.8 3F0225-01 / Attachment 9 / Page 8 of 10 A1 I
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4.0 Conclusions The above comparison illustrates that for H-3, C-14, and Tc-99, the inclusion of the waterborne pathways would lead to reduced DCGL values but only if wells were permitted within the 30-year period post license termination. Additionally, including the 30-year restriction on groundwater extraction, the waterborne dose contributions for H-3, C-14 and Tc-99 are essentially zero; there is no waterborne dose contribution and the DCGLs for the Resident Farmer in the LTP CH 5 remain conservative.
Salinity of the groundwater for the CR3 site can be expected to increase in the future due to rising sea water levels creating a larger inland geographical saline area. Duke Energy has designated the CR3 as industrial, supporting its future generation needs. Duke Energy originally chose the Resident Farmer scenario as a conservative bounding scenario at license termination but clearly that scenario will not occur in the next 30-plus years.
Household use and irrigation with groundwater is implausible for the foreseeable future.
Characterization has con"rmed that there are no detectable levels of radioactive contamination of groundwater for CR3; and the RESRAD-ONSITE modeling shows that assuming groundwater extraction is permitted post 30-years, the waterborne dose contribution is essentially zero.
The position established in the LTP is that groundwater pathways are not applicable due to restrictions on extraction under State of Florida regulations; salinity level further prevents its use. This TBD demonstrates that even if considered, the waterborne pathways would not increase the evaluated dose to the AMCG, conservatively assumed to be a Resident Farmer.
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5.0 References Haley & Aldrich, Inc. (H&A), (2024a). Development of Site-Speci"c Values for RESRAD Hydrogeological and Hydrological Parameters, ADP CR3 Decommissioning Project, Crystal River, Florida. December 9, 2021. Revised January 31, 2024.
Haley & Aldrich, Inc. (H&A), (2024b). Groundwater Well and Withdrawal Permit Limits Under the Florida Department of Environmental Protection Regulations, and February 28, 2024 March 21, 2024.
US Nuclear Regulatory Commission (NRC), (2020). NUREG/CR-7267, Default Parameter Values and Distribution in RESRAD-ONSITE V7.2, RESRAD-BUILD V3.5, and RESRAD OFFSITE V4.0 Computer Codes.
US Nuclear Regulatory Commission (NRC). (2022). NUREG-1757, Vol. 2, Consolidated Decommissioning Guidance Characterization, Survey, and Determination of Radiological Criteria, page 3-4. July.
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