ML24214A057

Enclosure 12, ENG-OCS-009 Revision: 0, Area Factors for Soil – Industrial Use Scenario, August 4, 2022

ML24214A057
Person / Time
Site:	Oyster Creek
Issue date:	08/04/2022
From:	Bisson J BHI Energy, Holtec Decommissioning International, Westinghouse
To:	Office of Nuclear Reactor Regulation
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References
HDI-OC-24-018 ENG-OCS-009, Rev 0
Download: ML24214A057 (1)

Text

ENGINEERING CALCULATION

Area Factors for Soil - Industrial Use Scenario ENG-OCS-009 Revision: 0 August 4, 2022

Prepared by:

BHI Energy 97 Libbey Industrial Pkwy Weymouth, MA

Prepared by

Approved by BHI Engineering ENG -OCS-009 AF Values for Soil - Industrial Use Scenario Rev. 0

1.0 PURPOSE The purpose of this calculation is to develop area factors (AFs) for use with derived concentration guideline levels (DCGL) values for assessing soil at the Oyster Creek Station (OCS) site.

2.0 APPLICABILITY This calculation addresses only the development of AF values for use with DCGLs for surface soils at the OCS site.

3.0 REFERENCES

3.1 BHI Energy Engineering Procedure ENG-AP-02, Verification of Software Operability 3.2 ANL/EVS/TM-18/1, RESRAD-Onsite 7.2 Users Guide, April 2018 3.3 ENG-OCS-008, Derived Concentration Guideline Levels for Soil-Industrial Use Scenario 3.4 NUREG-1575, Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM),

August 2000 3.5 Radionuclide Selection for DCGL Development-Oyster Creek Station Site Characterization Project, January 2022 3.6 NUREG/CR-5512, Volume 1, Residual Radioactive Contamination from Decommissioning:

Technical Basis for Translating Contamination Levels to Annual Total Effective Dose Equivalent ,

Final Report, U.S. Nuclear Regulatory Commission, October 1992.

4.0 DISCUSSION The operability of the RESRAD-Onsite 7.2 computer code was verified on each computer used for code executions in accordance with BHI Energy Engineering procedure ENG-AP-02, Verification of Software Operability [3.1]. The RESRAD-Onsite 7.2 Users Guide [3.2] provided instructions for code use.

The method applied in the calculation of AFs is the same as that applied in BHI Energy Engineering calculation ENG-OCS-003, Derived Concentration Guideline Levels for Soil-Industrial Use Scenario [3.3],

in the development of OCSs soil DCGL values. However, the input values for the following RESRAD-Onsite input parameters were adjusted to account for the reduced areas of the contaminated zone (CZ):

• the size of the CZ

• the length of parallel to aquifer flow The base case for AFs was an assumed CZ equal to 2,000 m2 because that is the maximum size for a MARSSIM Class 1 land survey unit [3.4]. AF values are calculated from the peak of the mean (POM) doses generated by RESRAD-Onsite. The following equation was used:

AF = (POM2000/POMi)

Where AF = the area factor (unitless)

POM2000 = peak of the mean dose for the base case (mrem/y), and POMi = peak of the mean dose for the reduced area i (mrem/y), where i is set at various sized areas

5.0 INPUT 5.1 Source input consisted of the radionuclides-of-concern (ROCs) identified for the OCS site

[3.5]. Table 1 provides the ROCs for the OC site.

Page 1 of 5 BHI Engineering ENG -OCS-009 AF Values for Soil - Industrial Use Scenario Rev. 0 Table 1: Radionuclides-of-Concern for input to RESRAD-Onsite

ROCa Progenyb ROCa Progenyb Am-241 Np-237, Th-229, U-233 Nb-94 ---

C-14 --- Ni-63 ---

Cm-243 Ac-227, Am-243, Pa-231, Np-237 Th-229, U-233 Pu-239, U-235 Cm-244 Pu-240, Ra-228, Th-228, Pu-238 Pb-210, Po-210, Ra-226, Th-232, U-236 Th-230, U-234 Cs-137 --- Pu-239 Ac-227, Pa-231, U-235 Co-60 --- Pu-240 Ra-228, Th-228, Th-232, U-236 Eu-152 Gd-152 Pu-241 Am-241, Np-237, Th-229, U-233 Eu-154 --- Sb-125 Te-125m Fe-55 --- Sr-90 ---

H-3 --- Tc-99 ---

Mn-54 ---

a ROC = radionuclide-of-concern identified for the OCS site.

b Included automatically with input of parent ROC.

5.2 The Industrial Use Scenario was modeled in the development of the OCS soil DCGL values. The pathways used to estimate human radiation exposure resulting from residual radioactivity in the soil under that scenario include the following:

• Direct external radiation exposure pathway

• Inhalation exposure pathway

• Aquatic food ingestion exposure pathway

• Inadvertent ingestion of contaminated soil These 4 pathways are active exposure pathways in the development of AFs.

5.3 Eight sizes for the CZ were assumed: 2000 m2 (base case), 1000 m2, 500 m2, 100 m2, 50 m2, 10 m2, 5 m2, and 1m2.

5.3.1 As the area of the CZ decreases, the value for the length parallel to aquifer flow (LCZPAQ) also decreases. The CZ is assumed to be circular, so the value for LCZPAQ is equal to the diameter of the circle:

LCZPAQ (m) = 2 (A/)

Table 2 shows the input values for the CZ and LCZPAQ.

Table 2: RESRAD-Onsite Input Parameters for Assumed CZ Sizes RESRAD Input Value Parameter CZ (m2) 2,000 1,000 500 100 50 10 5 1 LCZPAQ (m) 50 36 25 11 8.0 3.6 2.5 1.1

5.4 Except for the parameter values shown in Table 2, input parameter values used in AF calculations were the same values as those used to calculate DCGLs.

Page 2 of 5 BHI Engineering ENG -OCS-009 AF Values for Soil - Industrial Use Scenario Rev. 0 6.0 RESULTS 6.1 The POM doses for reduced CZ sizes are presented by ROC in Table 3. The AF values for each ROC are presented in Table 4.

6.2 AF values were generated from the POM doses using the following equation:

AF = (POM2000/POMi)

Where:

AF = the area factor (unitless)

POM2000 = peak of the mean dose for the base case (mrem/y), and POMi = peak of the mean dose for the reduced area i (mrem/y), where i is set at various sized areas

Table 3: RESRAD-Onsite Dose Results by CZ Size POM Dose (mrem/y) for CZ Size (m2):

ROC 2000 1000 500 100 50 10 5 1 Am-241 3.19E-02 3.16E-02 2.12E-02 1.20E-02 1.02E-02 6.79E-03 5.02E-03 2.62E-03 C-14 3.64E-04 2.13E-04 1.30E-04 2.96E-05 1.42E-05 3.48E-06 2.01E-06 6.22E-07 Cm-243 1.29E-01 1.27E-01 1.19E-01 1.03E-01 9.39E-02 6.13E-02 4.13E-02 1.45E-02 Cm-244 1.28E-02 1.26E-02 7.05E-03 2.43E-03 1.79E-03 1.15E-03 1.01E-03 8.10E-04 Co-60 2.91E+00 2.88E+00 2.82E+00 2.53E+00 2.30E+00 1.47E+00 9.74E-01 3.16E-01 Cs-137 6.42E-01 6.34E-01 6.22E-01 5.61E-01 5.12E-01 3.30E-01 2.19E-01 7.23E-02 Eu-152 1.31E+00 1.30E+00 1.27E+00 1.14E+00 1.04E+00 6.66E-01 4.43E-01 1.44E-01 Eu-154 1.42E+00 1.40E+00 1.37E+00 1.23E+00 1.12E+00 7.16E-01 4.75E-01 1.55E-01 Fe-55 2.97E-06 2.97E-06 1.49E-06 3.08E-07 1.60E-07 3.95E-08 2.40E-08 1.07E-08 H-3 6.33E-05 4.48E-05 3.17E-05 1.41E-05 1.00E-05 4.47E-06 3.16E-06 1.41E-06 Mn-54 6.77E-01 6.69E-01 6.55E-01 5.88E-01 5.37E-01 3.44E-01 2.29E-01 7.50E-02 Nb-94 1.85E+00 1.83E+00 1.79E+00 1.61E+00 1.47E+00 9.44E-01 6.28E-01 2.06E-01 Ni63 3.21E-06 3.21E-06 1.62E-06 3.42E-07 1.82E-07 5.11E-08 3.38E-08 1.82E-08 Np-237 4.05E-01 4.01E-01 3.67E-01 3.11E-01 2.83E-01 1.84E-01 1.23E-01 4.31E-02 Pu-238 2.05E-02 2.03E-02 1.13E-02 3.89E-03 2.86E-03 1.84E-03 1.62E-03 1.30E-03 Pu-239 2.19E-02 2.18E-02 1.18E-02 3.70E-03 2.60E-03 1.55E-03 1.35E-03 1.06E-03 Pu-240 2.19E-02 2.17E-02 1.18E-02 3.68E-03 2.58E-03 1.54E-03 1.34E-03 1.05E-03 Pu241 9.39E-04 6.87E-04 6.18E-04 1.20E-04 8.85E-05 5.49E-05 4.83E-05 3.86E-05 Sb-125 4.13E-01 4.08E-01 4.01E-01 3.62E-01 3.30E-01 2.13E-01 1.42E-01 4.70E-02 Sr-90 5.50E-03 5.44E-03 4.93E-03 4.14E-03 3.75E-03 2.38E-03 1.59E-03 5.21E-04 Tc-99 4.86E-05 2.83E-05 1.90E-05 1.40E-05 1.24E-05 7.93E-06 5.30E-06 1.81E-06

Page 3 of 5 BHI Engineering ENG -OCS-009 AF Values for Soil - Industrial Use Scenario Rev. 0

Table 4: Area Factors for Soil DCGLs Area Factor for Area CZ (m2):

ROC 2000 1000 500 100 50 10 5 1 Am-241 1 1 2 3 3 5 6 12 C-14 1 2 3 12 26 104 181 585 Cm-243 1 1 1 1 1 2 3 9 Cm-244 1 1 2 5 7 11 13 16 Co-60 1 1 1 1 1 2 3 9 Cs-137 1 1 1 1 1 2 3 9 Eu-152 1 1 1 1 1 2 3 9 Eu-154 1 1 1 1 1 2 3 9 Fe-55 1 1 2 10 19 75 124 278 H-3 1 1 2 4 6 14 20 45 Mn-54 1 1 1 1 1 2 3 9 Nb-94 1 1 1 1 1 2 3 9 Ni63 1 1 2 9 18 63 95 176 Np-237 1 1 1 1 1 2 3 9 Pu-238 1 1 2 5 7 11 13 16 Pu-239 1 1 2 6 8 14 16 21 Pu-240 1 1 2 6 8 14 16 21 Pu241 1 1 2 8 11 17 19 24 Sb-125 1 1 1 1 1 2 3 9 Sr-90 1 1 1 1 1 2 3 11 Tc-99 1 2 3 3 4 6 9 27

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