ML22034A595

FC-18-002 Rev. 0 - Potential Radionuclides of Concern During the Decommissioning of Fort Calhoun Station

ML22034A595
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Site:	Fort Calhoun
Issue date:	03/06/2018
From:	Brehm D Omaha Public Power District
To:	Office of Nuclear Reactor Regulation
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ML22034A602	List: LIC-22-0001, Well Water Results with River Stage ML22034A559 ML22034A594 ML22034A595
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LIC-22-0001 FC-18-002
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UHHU OaMaMeePowerDUrict Page 1 of 15 FC-18-002 Revision 0 Potential Radionuclides of Concern During the Decommissioning of Fort Calhoun Station Prepared By: DM Brehm 3/6/2018 Date Reviewed By: AK Barker (j Jjj sjU? 1 Date '

Approved By: DRWhisler Date

Potential Radionuclides of Concern During FC-18-002 HFFH OmihiPatBePaterDUikl the Decommissioning of Fort Calhoun Station Revision 0 Page 2 of 15 ACRONYMS AND ABBREVIATIONS BWR Boiling water reactor Cl/g Curies per gram MDA Minimum detectable activity MWe Megawatts electric NRG United States Nuclear Regulatory Commission PWR Pressurized water reactor

Potential Radionuclides of Concern During FC-18-002 the Decommissioning of Fort Calhoun Station Revision 0 Page 3 of 15 1.0 PURPOSE The purpose of this Technical Basis Document is to document an Initial suite of potential radionuclides of concern for the decommissioning of Fort Calhoun Station. Industry guidance is reviewed as are the analysis results associated with representative samples associated with various site activities. The initial suite of potential radionuclides will be used to help define sample analysis requirements associated with decommissioning activities including characterization activities and license termination plan development. It is expected that as additional samples are collected and analyzed, this initial suite of radionuclides will be updated and will eventually represent those long lived radionuclides with a potential to be present at the time of the final status survey.

2.0 DISCUSSION Fort Calhoun Station (FCS)is located in eastern Nebraska, on the western shore of the Missouri River approximately 20 miles north of Omaha, Nebraska. FCS consists of one pressurized water reactor supplied by Combustion Engineering.

The reactor was rated at approximately 500 MWe. The reactor was permanently shut down on October 24, 2016.

As Decommissioning activities commence, numerous samples will be collected requiring radiological analysis. These radiological analyses may support operational health physics concerns; free release surveys, characterizations of equipment, buildings, and the environment; and planning activities associated with the development of a license termination plan. This initial suite of potential radionuclides will help guide the required analyses of these samples. As the decommissioning progresses, additional samples will be collected and analyzed allowing for the initial suite of radionuclides to be updated. Some radionuclides may prove not to have been present, some radionuclides may be removed with the removal of a specific source term, some radionuclides may continue to decay to insignificant activity concentrations, and some radionuclides may be eliminated due to insignificant dose contributions. Eventually an updated suite of radionuclides representative of radionuclides with a potential to be present at the time of final status survey will be prepared. The ultimate goal being to establish a concise list, or lists, of radionuclides present in the various media subject to final status survey.

3.0 INDUSTRY GUIDANCE To aid in the development of an initial suite of potential radionuclides of concem for the decommissioning of FCS, several industry guidance documents were reviewed to generate a list of potential radionuclides. These guidance documents included NUREG/CR-3474, NUREG/CR-4289 and WINGO-1191.

Radionuclide half-lives were obtained from ICRP Publication 38.

NUREG/CR-3474 provides tables of theoretical activation products for both pressurized water reactors(PWR)and boiling water reactors(BWR)based on

Potential Radionuclides of Concern During FC-18-002 UHHU the Decommissioning of Fort Calhoun Station OmbiPabBePimfDiarkl Revision 0 Page 4 of 15 typical materials of construction, anticipated impurities, assumed neutron flux, etc. Four tables from NUREG/CR-3474 were reviewed in order to prepare a list of potential radionuclides with half lives of two years or greater. These tables from NUREG/CR-3474 were as follows:

• Table 5.1-Activation of PWR Internals (Ci/gm), Type 305L Stainless Steel, 30 EFPY at Core Axial Midplane

• Table 5.3-Activation of Pressure Vessel Walls(Ci/gm), 30 EFPY at Core Axial Midplane

• Table 5.4-Activation of PWR Bioshield (Ci/gm), Average Concrete, 30 EFPY at Core Axial Midplane

• Table 5.6-Activation of PWR Bioshield (Ci/gm), Average Rebar, 30 EFPY at Core Axial Midplane Based on a review of the above tables. Table 3-1 was prepared listing the potential radionuclides due to neutron activation of reactor components.

Table 3-1 Potential Activation Products Radionucllde Half Life (years) Radionucllde Half Life (years)

H-3 1.24E1 Ag-108m 1.27E2 C-14 5.73E3 Sn-121m 5.50E1 CI-36 3.01E5 1-129 1.57E7 Ar-39 2.69E2 Ba-133 1.07E1 Ca-41 1.40E5 Cs-134 2.06E0 Mn-53 3.70E6 Cs-137 3.00E1 Fe-55 2.70E0 Pm-145 1.77E1 Ni-59 7.50E4 Sm-146 1.03E8 Co-60 5.27E0 Sm-151 9.00E1 Ni-63 9.60E1 Eu-152 1.33E1 Se-79 6.50E4 Eu-154 8.80E0 Kr-81 2.10E5 Eu-155 4.96E0 Kr-85 1.07E1 Tb-158 1.50E2 Sr-90 2.91E1 Ho-166m 1.20E3 Nb-92m 2.70E7 Hf-178m 3.10E1 Zr-93 1.53E6 Pb-205 1.43E7 Mo-93 3.50E3 U-233 1.58E5 Nb-94 2.03E4 Pu-239/240 2.41 E4 Tc-99 2.13E5 NUREG/CR-4289 provides tables of actual sample analysis results obtained from seven nuclear power plants, both PWRs and BWRs, and included both fission and activation products. Four tables from NUREG/CR-4289 were reviewed in order to supplement the list of radionuclides with half lives greater than two years presented in Table 3-1. These tables were as follows:

Potential Radionuclides of Concern During uhhu OmihiPatBePowerDIstikt the Decommissioning of Fort Calhoun Station FC-18-002 Revision 0 Page 5 of 15

• Table 4.1-Long-lived Residual Radionuclide Compositions in Total Plant inventories at Seven Nuclear Generating Stations.

• Table 4.2-Concentration Ranges of Radionuclides in Corrosion Films on Piping Exposed to Primary Reactor Coolant.

• Table 4.3-Concentration Ranges of Radionuclides in Corrosion Films Internally Deposited in Piping and Hardware Exposed to Liquid Radwastes and Secondary Coolant.

• Table 4.4-Concentration Ranges of Radionuclides Associated with Concrete from Highly Contaminated Areas Within Selected Nuclear Generating Stations.

Based on a review of these four tables from NUREG/CR-4289, Table 3-2 was prepared listing potential radionuclides with half lives of two years or greater that were not included in Table 3-1.

Table 3-2 Additional Fission and Activation Products Based on Actual Analysis Results Radionuclide Half Life (years)

PU-23B 8.77E1 Np-237 2.14E6 Am-241 4.32E2 Am-243 7.3BE3 Cm-244 1.81E1 WINCO-1191, Reference 6.3, presents a theoretical listing of radionuclides expected to be found in both PWRs and BWRs and includes both fission and activation products. Of particular interest is Table 1 entitled "Radionuclides Found in Nuclear Power Reactors (limited to half-lives longer than 50 days)."

Table 1 from WINCO-1191 was reviewed in order to supplement the lists of radionuclides with half lives greater than two years presented in Tables 3-1 and 3-2.

Based on a review of Table 1 from WINCO-1191, Table 3-3 was prepared listing potential radionuclides with half lives of two years or greater that were not included in Table 3-1 or Table 3-2.

Table 3-3 Additional Fission and Activation Products Based on Theoretical Considerations Radionuclide Half Life (years)

Sb-125 2.77E0 Pm-147 2.62E0 Pu-241 1.44E1

Potential Radionuclides of Concern During FC-18-002 UHHSS OmtlaPtMePtmerOlslricI the Decommissioning of Fort Calhoun Station Revision 0 Page 6 of 15 4.0 REPRESENTATIVE SAMPLES To further aid in the development of an initial suite of potential radionuclides of concern for the decommissioning of PCS the analytical results of representative samples collected at PCS were reviewed. In general the samples associated with these results were collected from within various waste/process streams and sent off site for a 10CPR61-type of analysis. Table 4-1 provides a summary of the samples.

Table 4-1 Summary of Samples Analyzed Sample Date Media Description Number/identifier Collected L70787 10/18/2016 Smear smear samples from various plant locations.

L71393 1/8/2016 Resin primary coolant purification media L71393 2/4/2018 Charcoal liquid waste processing media L71393 7/29/2013 Resin liquid waste processing media L76112 12/20//2017 Liquid Spent Fuel Pool 10-Oct-16-200029 10/18/2016 Smear Room 506 sink 04-Jan-17-200006 1/4/2017 Smear Room 60 sink 10-Oct-16-200032 10/18/2016 Smear Spent Fuel Pool 10-Oct-16-200026 10/18/2016 Smear Room 23 sump 09-NOV-16-200010 11/9/2016 Smear underside of reactor vessel 04-NOV-16-200011 11/4/2016 filter upper reactor cavity air sample Attachment 1 contains a summary of each of the analysis results for the samples.

The data summarized in Attachment 1 shows the radionuclides analyzed for, the half-life of each of the radionuclides listed, the activity concentration of each radionuclide detected, the uncertainty in the activity concentration of each radionuclide detected, and the minimum detectable activity(MDA)concentration of each radionuclide analyzed for but not detected. In reviewing which of the radionuclides analyzed for were detected, the MDA of the radionuclides not detected must be considered to ensure that the analytical techniques used were sufficient to detect all the radionuclides of concern.

Attachment 2 contains a summary of the radionuclides In each of the samples that were detected. The radionuclide activity concentrations for each of the radionuclides detected were decay corrected to February 15, 2018. Based on the decay corrected activity concentrations, the relative fraction represented by each radionuclide is provided.

Based on the data contained in Attachment 2, a list of radionuclides with relative fractions equal to, or greater than, 0.001% was generated. Table 4-2 lists those radionuclides that were detected and had a relative fraction equal to, or greater than, 0.001%.

Potential Radionuclides of Concern During FC-18-002 ilFFIl the Decommissioning of Fort Calhoun Station OnabaPutBePimerDlsbkl Revision 0 Page 7 of 15 Table 4-2 Radionuc ides Relative Fractions Equal To, or Greater Than,0.001%

^Ci Composite Half-life Nuclide  % In Plant  % alpha  % beta % gamma Sample (Years)

Cs-137 2.83E+01 52.8% 52.8% 79.8% 30.04 Ni-63 1.46E+01 27.3% 27.3% 100.10 Co-60 6.90E+00 12.9% 12.9% 19.5% 5.27 Fe-55 3.18E+00 5.9% 5.9% 2.73 Sr-90 2.60E-01 0.49% 0.49% 28.74 Cs-134 2.10E-01 0.39% 0.39% 0.59% 2.06 Pu-241 3.26E-02 0.061% 0.06% 14.35 Mn-54 2.37E-02 0.044% 0.04% 0.07% 0.86 H-3 7.33E-03 0.014% 0.01% 12.33 ftg-IIOm 6.52E-03 0.012% 0.01% 0.02% 0.68 Am-241 2.89E-03 0.005% 59.2% 0.0082% 432.20 Cm-243/244 9.27E-04 0.002% 18.97% 29.10 Pu-238 8.96E-04 0.002% 18.32% 0.003% 87.70 Pu-239{1) 1.73E-04 0.0003% 3.53% 24,110 (1) Pu-239 Is included due to its significant a pha contri )ution.

5.0 INITIAL SUITE OF POTENTIAL RADIONUCLIDES To prepare the initial suite of potential radionuclides of concern for the decommissioning of PCS, NUREG/CR-3474 Tables 4.1, 4.2, 4.3, and 5.13 were used as a basis to form a single list after eliminating noble gases and other short lived radionuclides since they are not expected to be present at the time of final status survey. Table 5-1 provides the combined list of potential radionuclides.

Oprb OauhiMBtPowerOlttrict Potential Radlonuclides of Concern During the Decommissioning of Fort Calhoun Station FC-18-002 Revision 0 Page 8 of 15 Table 5-1 Potential Radlonuclides Radionucllde Half Life (years) Radionucllde Half Life (years)

H-3 12.3 Cs-134 2.07 C-14 5,370 Cs-137 30.04 CI-36 301,000 Pm-145 17.7 Ca-41 103,000 Pm-147 2.62 Mn-53 3.70E6 Sm-146 1.03E8 Fe-55 2.73 Sm-151 90 Ni-59 76,000 Eu-152 13.54 Co-60 5.27 Eu-154 8.59 NI-63 100.1 Eu-155 4.76 Se-79 650,000 Tb-158 180 Sr-90 28.74 Ho-166m 1,200 Nb-92m 3.47E7 Hf-178m 31 Zr-93 1.53E6 Pb-205 1.52E7 Mo-93 4,000 U-233 159,200 Nb-94 20,300 Pu-238 87.7 Tc-99 211,100 Pu-239/240 24,110 Ag-108m 418 Pu-241 14.35 Sn-121m 55 Np-237 2.144E6 Sb-125 2.76 Am-241 432.2 1-129 1.57E7 Am-243 7,370 Ba-133 10.52 Cm-243/244 29.1 The bolded radlonuclides in Table 5-1 represent those radlonuclides that were identified in the samples collected from the PCS site.

Upon review of the radlonuclides listed in Table 5-1 that were not identified in the samples collected at the PCS site, it became apparent that some of the radlonuclides were only included based on the theoretical considerations related to neutron activation. In order to pare down the list of potential radlonuclides, the calculated activity concentrations of these theoretical neutron activation products were compared to the calculated activity concentrations of Co-60, Cs-137, and NI-63. As shown in Attachment 2, the most prominent activation products Identified In the samples collected at PCS were Co-60, Cs-137, and Ni-63.

Theoretical neutron activation products listed in Table 5-1 that have calculated activity concentrations less than 0.001% of the calculated activity concentrations of Co-60, C§^1^^7rahdlsJh63ivtMia^minated from further consideration. Tables 5.1 and ^^of NUREG/CR-3734 prj^^ calculated activity concentrations for PWR Internals and Ve5setT/VMs"based on theoretical considerations for neutron activation products. Tables 5.1 and 5.4 of NUREG/CR-6567 contains results from analysis of materials obtained from operating reactors. WINCO-1191 Tables 1 and 2 contains a list of radlonuclides found in nuclear reactors that have significant (for decommissioning/disposal purposes) radiological half-lives.

Based on the review of this data, the following radlonuclides have been eliminated from further consideration: CI-36, Ca-41, Mn-53, Se-79, Nb-92m, Zr-93, Mo-93, Ag-108m. Sn-12lm, 1-129, Ba-133, Pm-145, Sm-146, Sm-151,

Potential Radlonuclldes of Concern During FC-18-002 IIFFII OmihiPabliePoweraorict the Decommissioning of Fort Calhoun Station Revision 0 Page 9 of 15 Eu-155, Tb-158, Ho-166m. Hf-187m, Pb-205, and U-233. Additionally, Cs-134, Cs-137, Sr-90, Pu-238, Pu-238, Pu-241, and Cm-243/244 were included due to FCS's history with failed fuel elements.

Based on the elimination of the theoretical neutron activation products due to having low activity concentrations relative to either Co-60 or Ni-63, an initial suite of potential radionuclides of concern for the decommissioning of PCS has been prepared. Table 5-2 lists these radionuclides.

Table 5-2 Initial Suite of Potential Radionuclides Radionuclide Half Life (years)

H-3 12.3 Pe-55 2.73 Co-60 5.27 Ni-63 100.1 Sr-90 28.74 Cs-134 2.07 Cs-137 30.04 Pu-238 87.7 Pu-239/240 24,110 Pu-241 14.35 Am-241 432.2 Cm-243/244 29.1 As the decommissioning of PCS progresses the list of radionuclides in Table 5-2 may be updated as needed. The collection and analysis of site specific samples should be considered to support specific site activities and or requirements such as the derivation of surrogate relationships between the radionuclides present in support of the final status survey.

6.0 REFERENCES

6.1 NUREG/CR-3474. "Long-Lived Activation Products in Reactor Materials", Pacific Northwest Laboratory, 1984.

6.2 NUREG/CR-4289,"Residual Radionuclide Concentration Within and Around Commercial Nuclear Power Plants; Origin, Distribution. Inventory, and Decommissioning Assessment," Pacific Northwest Laboratory, 1985.

6.3 NUREG/CR-6567,"Low-Level radioactive Waste Classification, Characterization, and Assessment: Waste Streams and Neutron-Activated Metals," Pacific Northwest National Laboratory, 2000.

6.4 WINCO-1191,"Radionuclides in United States Commercial Nuclear Power Reactors," Westinghouse Idaho Nuclear Company, Inc., 1994.

Potential Radionuclldes of Concern During FC-18-002 Anabf AMfcftocfD&Htf the Decommissioning of Fort Calhoun Station Revision 0 Page 10 of 15 6.5 iCRP Publication 38, "Radionuclide Transformations - Energy and Intensity of Emissions," Pergamon Press, 1983.

7.0 ATTACHIVIENTS 7.1 Attachment 1 - Sample Analysis Results 7.2 Attachment 2 - Evaluation of Theoretical Neutron Activation Products Relative to Co-60 and Ni-63

Potential Radionuclldes of Concern During FC-18-002 Omb$PMePmmDlslikt the Decommissioning of Fort Calhoun Station Revision 0 Page 11 of 15 Attachment 1 Sample Analysis Results Decay Corrected to 2/15/2018 L70787 - Room 506 sink #1 Room 506 sink (10-Oct-16-200029) Room 60 sink (04-Jan-17-200006) L70787 - Room 60 sink #3 10/18/2016 10/18/2016 1/4/2017 10/18/2016 Nuclide uCi/Sample % in Plant Nuclide yCi/Sample % in Plant Nuclide uCi/Sample % in Plant Nuclide uCi/Sampie % in Plant Aq-IIOm Aq-IIOm Aq-IIOm 1.11E-04 1.053% Aq-110m 4.09E-04 0.334%

Am-241 Am-241 Am-241 Am-241 3.22E-05 0.026%

Cm-243/244 Cm-243/244 Cm-243/244 Cm-243/244 3.06E-06 0.003%

Co-57 Co-57 Co-57 1.06E-05 0.100% Co-57 Co-58 1.87E-05 0.446% Co-58 4.33E-07 0.022% Co-58 8.27E-05 0.783% Co-58 1.66E-05 0.014%

Co-60 4.20E-04 10.018% Co-60 3.49E-04 18.060% Co-60 9.85E-03 93.265% Co-60 1.13E-01 92.051%

Cr-51 Cr-51 Cr-51 2.05E-07 0.002% Cr-51 Cs-134 Cs-134 Cs-134 Cs-134 Cs-137 2.00E-03 47.665% Cs-137 1.58E-03 81.918% Cs-137 1.32E-04 1.246% Cs-137 6.90E-04 0.564%

Fe-55 1.04E-03 24.694% Fe-55 Fe-55 Fe-55 2.17E-03 1.775%

H-3 H-3 H-3 H-3 Mn-54 1.25E-05 0.298% Mn-54 Mn-54 2.18E-04 2.065% Mn-54 1.67E-03 1.363%

Nb-95 Nb-95 Nb-95 6.75E-06 0.064% Nb-95 6.38E-07 0.001%

Ni-63 7.07E-04 16.879% Ni-63 Ni-63 Ni-63 4.21 E-03 3.445%

Pu-238 Pu-238 Pu-238 Pu-238 8.37E-06 0.007%

Pu-239 Pu-239 Pu-239 Pu-239 4.38E-06 0.004%

Pu-241 Pu-241 Pu-241 Pu-241 3.35E-04 0.274%

Sr-90 Sr-90 Sr-90 Sr-90 1.42E-04 0.116%

Y-90 Y-90 r-90 r-90 3.18E-59 0.000%

Zr-95 Zr-95 Zr-95 1.50E-04 1.421% Zr-95 2.90E-05 0.024%

appB Om^PutilkPemrDlsMtt Potential Radionuclides of Concern During the Decommissioning of Fort Calhoun Station FC-18-002 Revision 0 Page 12 of 15 Attachment 1 Sample Analysis Results Decay Corrected to 2/15/2018 L70787 - SFP SFP-(10-Oct-16-200032) L70787 - Rm 23 Sump #2 Rm 23 sump (18-0ct-16-200026) 10/18/2016 10/18/2016 10/18/2016 10/18/2016 Nuclide MCi/Sample % in Plant Nuclide uCi/Sample % in Plant Nuclide uCi/Sample % In Plant Nuclide uCi/Sample % in Plant Am-241 1.71E-04 0.032% ftm-241 ^m-241 Am-241 Cm-243/244 2.84E-06 0.001% Cm-243/244 Cm-243/244 Cm-243/244 Co-58 Co-58 Co-58 Co-58 Co-60 2.48E-02 4.691% Co-60 4.20E-04 2.171% Co-60 2.62E-03 17.363% Co-60 1.52E-03 54.238%

Cs-134 2.95E-03 0.558% Cs-134 1.08E-04 0.559% Cs-134 Cs-134 Cs-137 4.93E-01 93.280% Cs-137 1.88E-02 97.270% Cs-137 1.55E-03 10.272% Cs-137 1.17E-03 41.873%

Fe-55 3.13E-03 0.592% Fe-55 Fe-55 7.73E-03 51.226% Fe-55 1-129 1-129 1-129 1-129 1.09E-04 3.889%

Mn-54 Mn-54 Mn-54 7.99E-05 0.529% Mn-54 Ni-63 1.81E-03 0.343% Ni-63 Ni-63 3.11E-03 20.610% Ni-63 Pu-239 1.05E-05 0.002% Pu-239 Pu-239 Pu-239 Pu-241 2.56E-03 0.485% Pu-241 Pu-241 Pu-241 Sr-90 9.01 E-05 0.017% Sr-90 Sr-90 Sr-90 y-90 2.01 E-59 0.000% Y-90 Y-90 Y-90 Zr-95 Zr-95 Zr-95 Zr-95

Potential Radionuclldes of Concern During FC-18-002 UHFU OirmhtPiiMePowtrOislikt the Decommissioning of Fort Calhoun Station Revision 0 Page 13 of 15 Attachment 1 Sample Analysis Results Decay Corrected to 2/15/2018 Upper Rx Cavity A/S (09-NOV-16-200012) Upper Rx Cavity A/S (04-Nov-16-200011) Primary Resin (L71393) Process Charcoal (L71393) 9/16/2016 11/4/2016 1/8/2018 2/4/2018 Nuclide liCi/Sample % in Plant Nuclide nCi/Sampie % in Plant Nuclide pCI/Sample % in Plant Nuclide uCi/Sample % in Plant Aq-IIOm 5.50E-03 45.789% Aq-110m 1.2DE-05 0.375% Aq-110m Aq-IIOm Am-241 Am-241 Am-241 7.16E-04 0.001% Am-241 1.25E-05 0.005%

Cm-243/244 Cm-243/244 Cm-243/244 9.41 E-04 0.002% Cm-243/244 8.09E-06 0.003%

Co-57 Co-57 3.27E-06 0.102% Co-57 Co-57 3.42E-04 0.125%

Co-58 3.01 E-05 0.250% Co-58 2.93E-05 0.913% Co-58 Co-58 1.98E-02 7.203%

Co-60 6.19E-03 51.511% Co-60 3.02E-03 94.282% Co-60 7.85E+00 13.977% Co-60 6.73E-02 24.550%

Cr-51 3.00E-08 0.000% Cr-51 6.33E-09 0.000% Cr-51 Cr-51 Cs-134 Cs-134 Cs-134 3.11E-01 0.554% Cs-134 3.90E-04 0.142%

Cs-137 Cs-137 1.81 E-05 0.565% Cs-137 2.85E+01 50.790% Cs-137 2.70E-02 9.838%

Fe-55 Fe-55 Fe-55 4.31 E+00 7.680% Fe-55 4.93E-03 1.798%

Fe-59 6.58E-08 0.001% Fe-59 9.11E-08 0.003% Fe-59 Fe-59 H-3 H-3 H-3 H-3 1.11E-03 0.404%

Mn-54 2.10E-04 1.751% Mn-54 7.34E-05 2.289% Mn-54 5.71 E-02 0.102% Mn-54 1.07E-03 0.391%

Nb-95 1.16E-06 0.010% Nb-95 7.53E-07 0.023% Nb-95 Nb-95 Ni-59 Ni-59 NI-59 2.12E-01 0.377% Ni-59 1.55E-03 0.565%

Ni-63 Ni-63 NI-63 1.46E+01 25.971% NI-63 1.48E-01 53.951%

Pu-238 Pu-238 Pu-238 8.68E-04 0.002% Pu-238 2.76E-05 0.010%

Pu-239 Pu-239 Pu-239 1.50E-04 0.000% Pu-239 7.74E-06 0.003%

Pu-241 Pu-241 Pu-241 3.00E-02 0.053% Pu-241 1.44E-03 0.524%

Sb-125 Sb-125 Sb-125 Sb-125 1.27E-03 0.463%

Sr-90 Sr-90 Sr-90 2.67E-01 0.476% Sr-90 6.54E-05 0.024%

Zn-65 Zn-65 1.16E-05 0.362% Zn-65 Zn-65 Zr-95 8.27E-05 0.689% Zr-95 3.48E-05 1.086% Zr-95 Zr-95

Potential Radionuclides of Concern During FC-18-002 OmOtPaUcPimrimkt the Decommissioning of Fort Calhoun Station Revision 0 Page 14 of 15 Attachment 1 Sample Analysis Results Decay Corrected to 2/15/2018 Underside of Rx. Vessel SFP (L76112) 11/9/2016 12/20/2017

% in  % In Nuclide uCi/Sample Plant Nuclide nCi/Sample Plant Aq-110m 5.59E-04 0.433% Aq-IIOm Am-241 Am-241 Cm~243/244 Cm-243/244 Co-57 7.00E-05 0.054% Co-57 Co-58 1.33E-03 1.029% Co-58 2.31 E-06 0.017%

Co-60 1.24E-01 95.832% Co-60 5.32E-05 0.400%

Cr-51 1.32E-06 0.001% Cr-51 Cs-134 Cs-134 3.11E-05 0.234%

Cs-137 Cs-137 6.05E-03 45.462%

Fe-59 2.82E-06 0.002% Fe-59 H-3 H-3 6.73E-03 50.592%

Mn-54 2.20E-03 1.707% Mn-54 Nb-94 Nb-94 Nb-95 1.52E-05 0.012% Nb-95 Ni-63 Ni-63 3.89E-04 2.921%

Pu-239 Pu-239 Pu-241 Pu-241 Sr-90 Sr-90 4.97E-05 0.374%

U-233/234 U-233/234 Zn-65 5.40E-04 0.419% Zn-65 Zr-95 6.58E-04 0.510% Zr-95

Potential Radlonuclides of Concern During FC-18-002 HFFH OmalaMBePewtrOMct the Decommissioning of Fort Calhoun Station Revision 0 Page 15 of 15 Attachment 2 Evaluation of Theoretical Neutron Activation Products Relative to Co-60 and Ni-63 From Table 5.3 From Table 5.1 of NUREG ofNUREG CR-3734 CR-3734 Shroud Core Barrel Thermal Pads Vessel Cladding Pres Vessel Walls Activity Activity Activity Activity Activity Radlonuclides (Ci/fl) (Ci/fl) (Cl/p) (Ci/fl) (Ci/g)

Co-60 1.3E-01 1.4E-02 2.0E-03 3.3E-04 3.2E-02 Ni-63 1.8E-02 2.4E-03 3.8E-04 5.4E-05 5.7E-03 0.01% Limit 1.8E-06 2.4E-07 3.8E-08 5.4E-09 5.7E-07 01-36 5.1E-07 6.4E-08 1.0E-08 1.4E-09 1.6E-07 Ca-41 4.7E-09 5.6E-10 8.6E-11 1.2E-11 1.4E-09 Mn-53 3.3E-09 2.1E-10 I.OE-II 6.9E-12 4.6E-10 Se-79 6.1E-10 4.6E-11 4.7E-12 1.2E-12 1.0E-10 Nb-92m 1.2E-12 6.5E-14 3.2E-15 2.0E-15 4.5E-14 Zr-93 1.1E-10 3.9E-12 2.9E-13 8.6E-14 1.0E-11 Mo-93 9.4E-07 3.9E-08 2.1E-09 1.1E-09 7.7E-08 Aq-108m <1E-7 <9E-9 <1.1 E-9 <2.2E-10 <2.0E-8 Sn-121m 4.8E-09 3.4E-10 1.7E-11 1.1E-11 <7.6E-18 1-129 <6E-13 <1.4E-14 <7.9E-16 <1.1E-16 <4.2E-14 Ba-133 <6E-6 <3E-7 <4.5E-8 <7.1 E-9 <7.4E-7 Pm-145 8.9E-10 1.4E-10 2.2E-11 3.1E-12 <3.1E-10 Sm-146 1.0E-16 1.3E-17 6.7E-19 4.3E-19 2.9E-17 Sm-151 4.6E-09 4.5E-09 2.9E-09 5.9E-10 3.8E-9 Eu-152 0.00 9.1E-10 1.7E-07 7.6E-08 2.2E-14 Eu-154 5.7E-07 6.0E-07 6.2E-08 1.2E-08 9.1E-07 Eu-155 4.1E-07 1.4E-07 5.aE-09 5.2E-10 3.6E-07 Tb-158 1.9E-09 1.7E10 8.5E-12 5.6E-12 3.8E-10 Ho-116m 1.6E-07 1.3E-08 1.1E-09 3.0E-10 2.8E-08 Hf-178m 4.3E-08 2.8E-08 3.1E-09 1.2E-09 <3.7E-8 Pb-205 1.8E-12 1.3E-13 1.3E-14 3.4E-15 2.9E-13 U-233 <3.6E-10 1.0E-10 1.1E-11 3.4E-12 <1.6E-10 Bolded/shaded values exceed 0.01% of either the Co-60 or Ni-63 activity concentrations.