ML22342B266
| ML22342B266 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 12/08/2022 |
| From: | Ameren Missouri, Union Electric Co |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML22342B264 | List: |
| References | |
| ULNRC-06787 | |
| Download: ML22342B266 (1) | |
Text
Enclosure to ULNRC-06787 Page 1 of 19 Ameren Missouri Response to NRC RAIs 18 pages follow cover sheet
Enclosure to ULNRC-06787 Page 2 of 19 In its Request for Additional Information dated October 14, 2022, the NRC staff presented results from the safety review it had performed to date. The NRC staff described how it used the ARCON2 dispersion model for performing confirmatory checks of the ARCON96-NAI model runs performed by Ameren Missouri and its contractor. It was noted that the same ARCON96-formatted meteorological data files provided by Ameren Missouri were used for the confirmatory model runs. Numerous potentially questionable results were identified based on these confirmatory checks.
With respect to the controlling /Q values for a given accident scenario, the staff noted that different /Qs for all averaging times are not unusual when doing confirmatory checks (e.g., due to round-off, etc.).
Results are generally considered acceptable if the ARCON2 /Q estimates differ from the ARCON96-NAI /Qs by less than 5 percent. However, ARCON2 /Q values found to be higher than ARCON96-NAI values by more than 10 percent or by greater than 5 percent but less than 10 percent were identified.
All overpredictions occurred for only the longest accident averaging period (i.e., 4 to 30 days or 96 to720 hours).
It was noted that the data count for the 720-hour interval as indicated for the ARCON96-NAI model run and the /Q discrepancies between the two models are suspect without further clarification and/or justification for their use.
RAI-1a Given the preceding observations from the Staffs safety review, please confirm the validity of the ARCON96-NAI calculations of the 4-to 30-day (96-to 720-hour) averaging interval /Qs.
Response
In the original Callaway AST LAR submittal and supplemental enclosures (ML21272A167, ML21335A451, and ML22186A103), the minimum number of hours for the 720-hour /Q bin was incorrectly entered as 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> (rather than 648 as indicated in Table A-2 of RG 1.194). This input error led to a mixture of over and underpredicted 4-30 day /Q values. In response to RAI-1a through RAI-1c of NRC email dated October 14, 2022, this input was corrected and the ARCON models were rerun.
Likewise, for ARCON case clwA96_71 (diffuse containment to TSC Intake), the y and z values were zero, despite specification as a diffuse source; this led to a significant overprediction of the /Q. As such, the corrected /Q values are provided in parentheses for this case in Table 3-26 under the RAI-1c response.
During review of the /Q values used for the Fuel Handling Accident in the Fuel Handling Building (FHA in FHB) analysis, it was also identified that although the initial LAR and supplement listed limiting /Q values representing the Unit Vent release point, /Q values were not provided for the fuel building release point, which is the more conservative case with respect to control room dose. (The release/receptor pair for this case is the closest point of the fuel handling building and the control room air intakes on the control building.) Table 3-30 has been updated to reflect the correct limiting values used in the analysis.
Table 3-29 has also been updated to correctly show the fuel handling building assumed release point.
These changes to Table 3-30 and Table 3-29 were made to correctly reflect the FHA in FHB analysis. No changes to the analysis itself or the reported dose consequences have been made.
Enclosure to ULNRC-06787 Page 3 of 19 RAI-1b If that portion of the ARCON96-NAI dispersion model is inaccurate, revise the code and any affected documentation accordingly.
Response
The response to RAI-1a documents /Q calculation errors that resulted from incorrect user-provided inputs. No errors were identified with the ARCON96-NAI software.
RAI-1c Also, if that portion of the ARCON96-NAI dispersion model is inaccurate, either:
revise all of the model runs and any affected tables and/or figures in Enclosure 1 of the December 1, 2021, supplemental submittal, evaluate whether any of the conclusions drawn from the previous modeling results change (as reflected in Table 3-29 of Enclosure 1) and update as necessary, and revise all affected dose calculations; or document and provide other adequate justification for the retention of the previous ARCON96-NAI modeling results and related dose calculations and/or revisions to that modeling and those dose calculations.
Response
As discussed in the response to RAI-1a, inputs to the ARCON models were corrected and rerun. The following tables from the LAR and supplement are updated (and provided herein) to reflect the revised atmospheric dispersion factors.
Table 3-26: /Q Factors for Each Release/Receptor Pair Table 3-27: Bounding Stack/Plant Vent /Q Factors for Control Room Access Dose Analysis Table 3-28: Bounding RWST Vent /Q Factors for Control Room Access Dose Analysis Table 3-30: Control Room /Q Factors for Dose Analysis The tables are re-provided in their entirety. However, corrected Table 3-26 provides both the original and revised /Q values for the 4-to 30-day averaging period for each release/receptor pair. Corrected Tables 3-27, 3-28 and 3-30 also reflect the updated /Q values for the 4-to 30-day (96-to 720-hour) averaging period (but the originally provided values are not included). (The values were unchanged from the originally provided values in few cases).
The downstream dose calculations were subsequently revised to use the maximum of the original and revised /Q values for the 4-to 30-day period from Table 3-26. Additionally, a transcription error in the half-life of Te-133 used to generate the core nuclide inventory file for the dose calculations was corrected; while this error underestimated the Te-133 inventory, correction of the error had an extremely limited impact on dose results due to the short half-life of Te-133 (12.5 minutes). Table 3-32, "Fuel Source Term," has been updated (and provided herein) to reflect the correct Te-133 inventory.
Ultimately, only the dose results of the Loss of Coolant Accident (LOCA) and the Rod Ejection (RE)
Accident were impacted by the revised /Q values and Te-133 inventory correction. The remaining dose analyses saw no change in results despite use of the revised /Q values.
Enclosure to ULNRC-06787 Page 4 of 19 The following sections from the LAR are updated to reflect the Control Room isolation results and dose results due to revised atmospheric dispersion factors.
Section 3.3.2.5 Dose Due to Control Room Access Section 3.3.6.2.3.2 Rod Ejection Primary to Secondary Leakage Release Section 3.3.6.4 Rod Ejection Accident Results and Conclusions Section 3.3.8.1.5 Steam Generator Tube Rupture with Stuck Open ADV Control Room Section 3.3.9.2.3 Loss of Coolant Accident - Control Room Section 3.3.9.4 Loss of Coolant Accident Results and Conclusions Section 3.3.10.2.3 Fuel Handling Accidents - Control Room
Enclosure to ULNRC-06787 Page 5 of 19 Table 3-26. /Q Factors for Each Release/Receptor Pair Release Point Receptor Point 0-2 hr /Q (s/m3) 2-8 hr /Q (s/m3) 8-24 hr
/Q (s/m3) 1-4 day
/Q (s/m3) 4-30 day
/Q (s/m3)
Original 4-30 day
/Q (s/m3)
Revised Stack/Plant Vent
'A' CB intake (Emergency) 6.85E-04 5.64E-04 2.32E-04 1.41E-04 9.54E-05 9.95E-05 Stack/Plant Vent
'B' CB intake (Emergency) 6.86E-04 5.72E-04 2.32E-04 1.42E-04 9.57E-05 1.00E-04 Stack/Plant Vent Midpoint between Intakes 6.85E-04 5.69E-04 2.31E-04 1.42E-04 9.56E-05 9.99E-05 Stack/Plant Vent CB intake (Normal) 1.90E-03 1.58E-03 6.67E-04 3.90E-04 2.29E-04 2.65E-04 Stack/Plant Vent TSC Intake 1.74E-04 1.30E-04 6.30E-05 3.38E-05 2.43E-05 2.42E-05 RWST
'A' CB intake (Emergency) 7.31E-04 6.39E-04 2.61E-04 1.47E-04 8.85E-05 1.14E-04 RWST
'B' CB intake (Emergency) 7.47E-04 6.55E-04 2.71E-04 1.52E-04 9.17E-05 1.15E-04 RWST Midpoint between Intakes 7.33E-04 6.49E-04 2.66E-04 1.50E-04 8.95E-05 1.14E-04 RWST CB intake (Normal) 9.28E-04 6.97E-04 2.90E-04 1.69E-04 1.14E-04 1.22E-04 RWST TSC Intake 9.65E-05 7.82E-05 3.06E-05 1.86E-05 1.27E-05 1.32E-05 FHB Closest Point
'A' CB intake (Emergency) 1.15E-03 1.02E-03 4.17E-04 2.31E-04 1.55E-04 1.91E-04 FHB Closest Point
'B' CB intake (Emergency) 1.17E-03 1.04E-03 4.27E-04 2.34E-04 1.58E-04 1.94E-04 FHB Closest Point Midpoint between Intakes 1.15E-03 1.03E-03 4.21E-04 2.33E-04 1.57E-04 1.92E-04 FHB Closest Point CB intake (Normal) 2.23E-03 1.85E-03 7.49E-04 4.30E-04 2.94E-04 3.17E-04 FHB Closest Point TSC Intake 1.18E-04 9.44E-05 3.81E-05 2.28E-05 1.55E-05 1.66E-05 Closest ASD
'A' CB intake (Emergency) 1.74E-03 1.33E-03 6.50E-04 3.62E-04 2.96E-04 2.94E-04 Closest ASD
'B' CB intake (Emergency) 1.73E-03 1.33E-03 6.42E-04 3.60E-04 2.97E-04 2.95E-04 Closest ASD Midpoint between Intakes 1.74E-03 1.33E-03 6.50E-04 3.62E-04 2.96E-04 2.94E-04 Closest ASD CB intake (Normal) 1.66E-02 1.26E-02 5.91E-03 3.46E-03 2.91E-03 2.83E-03 Closest ASD TSC Intake 2.13E-04 1.80E-04 7.73E-05 4.12E-05 2.92E-05 3.02E-05 Closest MSSV
'A' CB intake (Emergency) 1.57E-03 1.35E-03 6.25E-04 3.51E-04 2.84E-04 2.85E-04 Closest MSSV
'B' CB intake (Emergency) 1.57E-03 1.35E-03 6.28E-04 3.51E-04 2.85E-04 2.85E-04 Closest MSSV Midpoint between Intakes 1.57E-03 1.35E-03 6.25E-04 3.51E-04 2.84E-04 2.85E-04 Closest MSSV CB intake (Normal) 1.76E-02 1.46E-02 6.74E-03 3.81E-03 3.05E-03 3.05E-03 Closest MSSV TSC Intake 1.88E-04 1.60E-04 6.43E-05 3.63E-05 2.67E-05 2.76E-05 Closest Main Steam Line Point
'A' CB intake (Emergency) 1.69E-03 1.56E-03 6.61E-04 3.83E-04 3.22E-04 3.23E-04 Closest Main Steam Line Point
'B' CB intake (Emergency) 1.69E-03 1.56E-03 6.61E-04 3.83E-04 3.22E-04 3.23E-04 Closest Main Steam Line Point Midpoint between Intakes 1.69E-03 1.56E-03 6.61E-04 3.83E-04 3.22E-04 3.23E-04 Closest Main Steam Line Point CB intake (Normal) 1.71E-02 1.57E-02 6.73E-03 3.87E-03 3.23E-03 3.24E-03 Closest Main Steam Line Point TSC Intake 7.64E-04 5.73E-04 2.38E-04 1.42E-04 9.38E-05 1.02E-04 Closest Feedwater Line Point
'A' CB intake (Emergency) 1.69E-03 1.54E-03 6.53E-04 3.75E-04 3.21E-04 3.22E-04
Enclosure to ULNRC-06787 Page 6 of 19 Table 3-26. /Q Factors for Each Release/Receptor Pair Release Point Receptor Point 0-2 hr /Q (s/m3) 2-8 hr /Q (s/m3) 8-24 hr
/Q (s/m3) 1-4 day
/Q (s/m3) 4-30 day
/Q (s/m3)
Original 4-30 day
/Q (s/m3)
Revised Closest Feedwater Line Point
'B' CB intake (Emergency) 1.69E-03 1.54E-03 6.53E-04 3.75E-04 3.21E-04 3.22E-04 Closest Feedwater Line Point Midpoint between Intakes 1.69E-03 1.54E-03 6.53E-04 3.75E-04 3.21E-04 3.22E-04 Closest Feedwater Line Point CB intake (Normal) 1.40E-02 1.24E-02 5.28E-03 3.07E-03 2.60E-03 2.61E-03 Closest Feedwater Line Point TSC Intake 7.56E-04 5.63E-04 2.35E-04 1.40E-04 9.02E-05 1.00E-04 Containment Maintenance Hatch (DSM52)
'A' CB intake (Emergency) 7.92E-04 6.98E-04 2.98E-04 1.64E-04 1.16E-04 1.28E-04 Containment Maintenance Hatch (DSM52)
'B' CB intake (Emergency) 8.01E-04 7.07E-04 3.00E-04 1.66E-04 1.17E-04 1.29E-04 Containment Maintenance Hatch (DSM52)
Midpoint between Intakes 7.96E-04 7.01E-04 2.99E-04 1.64E-04 1.16E-04 1.28E-04 Containment Maintenance Hatch (DSM52)
CB intake (Normal) 2.20E-03 1.92E-03 8.12E-04 4.39E-04 3.00E-04 3.56E-04 Containment Maintenance Hatch (DSM52)
TSC Intake 1.36E-04 1.08E-04 4.40E-05 2.55E-05 1.78E-05 1.90E-05 Steam Jet Air Ejector (Condenser Vacuum Pump)
'A' CB intake (Emergency) 1.64E-03 1.38E-03 5.94E-04 3.60E-04 3.22E-04 3.14E-04 Steam Jet Air Ejector (Condenser Vacuum Pump)
'B' CB intake (Emergency) 1.63E-03 1.37E-03 5.79E-04 3.52E-04 3.18E-04 3.09E-04 Steam Jet Air Ejector (Condenser Vacuum Pump)
Midpoint between Intakes 1.64E-03 1.38E-03 5.90E-04 3.58E-04 3.19E-04 3.11E-04 Steam Jet Air Ejector (Condenser Vacuum Pump)
CB intake (Normal) 4.66E-03 3.63E-03 1.44E-03 9.05E-04 7.16E-04 6.81E-04 Steam Jet Air Ejector (Condenser Vacuum Pump)
TSC Intake 2.29E-04 1.73E-04 7.20E-05 4.25E-05 2.89E-05 3.07E-05 Condenser
'A' CB intake (Emergency) 1.19E-03 9.96E-04 4.10E-04 2.59E-04 2.25E-04 2.18E-04 Condenser
'B' CB intake (Emergency) 1.15E-03 9.79E-04 4.00E-04 2.53E-04 2.20E-04 2.13E-04 Condenser Midpoint between Intakes 1.16E-03 9.91E-04 4.07E-04 2.55E-04 2.24E-04 2.17E-04 Condenser CB intake (Normal) 2.61E-03 1.99E-03 7.84E-04 4.95E-04 3.74E-04 3.55E-04 Condenser TSC Intake 4.20E-04 3.18E-04 1.31E-04 7.76E-05 5.16E-05 5.66E-05 TDAFP Exhaust Vent
'A' CB intake (Emergency) 1.16E-03 1.02E-03 4.40E-04 2.57E-04 2.16E-04 2.17E-04 TDAFP Exhaust Vent
'B' CB intake (Emergency) 1.16E-03 1.02E-03 4.40E-04 2.57E-04 2.18E-04 2.18E-04 TDAFP Exhaust Vent Midpoint between Intakes 1.16E-03 1.02E-03 4.40E-04 2.57E-04 2.18E-04 2.18E-04
Enclosure to ULNRC-06787 Page 7 of 19 Table 3-26. /Q Factors for Each Release/Receptor Pair Release Point Receptor Point 0-2 hr /Q (s/m3) 2-8 hr /Q (s/m3) 8-24 hr
/Q (s/m3) 1-4 day
/Q (s/m3) 4-30 day
/Q (s/m3)
Original 4-30 day
/Q (s/m3)
Revised TDAFP Exhaust Vent CB intake (Normal) 6.18E-03 5.58E-03 2.37E-03 1.39E-03 1.21E-03 1.20E-03 TDAFP Exhaust Vent TSC Intake 1.90E-04 1.49E-04 6.05E-05 3.56E-05 2.46E-05 2.61E-05 Emergency Personnel Access Hatch
'A' CB intake (Emergency) 8.55E-04 7.49E-04 3.20E-04 1.82E-04 1.42E-04 1.49E-04 Emergency Personnel Access Hatch
'B' CB intake (Emergency) 8.61E-04 7.54E-04 3.22E-04 1.84E-04 1.43E-04 1.50E-04 Emergency Personnel Access Hatch Midpoint between Intakes 8.59E-04 7.53E-04 3.22E-04 1.83E-04 1.43E-04 1.50E-04 Emergency Personnel Access Hatch CB intake (Normal) 2.66E-03 2.43E-03 1.01E-03 5.57E-04 4.14E-04 4.48E-04 Emergency Personnel Access Hatch TSC Intake 1.56E-04 1.24E-04 5.12E-05 3.01E-05 2.04E-05 2.19E-05 Containment (Diffuse)
CB intake (Normal) 7.12E-03 4.62E-03 2.04E-03 1.43E-03 1.05E-03 2.86E-04 Containment (Diffuse)
CB Intake (Emergency)
Midpoint 7.49E-04 5.32E-04 2.29E-04 1.50E-04 9.56E-05 1.02E-04 Containment (Diffuse) 10 m CB intake (Normal) 1.85E-03 1.23E-03 5.40E-04 3.84E-04 2.87E-04 2.82E-04 Containment (Diffuse) 20 m CB intake (Normal) 1.54E-03 1.00E-03 4.42E-04 3.10E-04 2.26E-04 2.24E-04 Containment (Diffuse)
TSC Intake 1.82E-04 (1.32E-
- 04) 1.45E-04 (1.06E-
- 04) 5.92E-05 (4.42E-05) 3.37E-05 (2.53E-
- 05) 2.41E-05 1.86E-05
Enclosure to ULNRC-06787 Page 8 of 19 Table 3-27 Bounding Stack/Plant Vent /Q Factors for Control Room Access Dose Analysis Time Period Stack/Plant Vent to Access Point 1
/Q (sec/m3)
Stack/Plant Vent to Access Point 2
/Q (sec/m3)
Stack/Plant Vent to Access Point 3
/Q (sec/m3)
Stack/Plant Vent to Access Point 41
/Q (sec/m3)
Stack/Plant Vent to Access Point 5
/Q (sec/m3)
Stack/Plant Vent to Access Point 6
/Q (sec/m3)
Stack/Plant Vent to Access Point 7
/Q (sec/m3) 0-2 hours 4.18E-05 8.59E-05 1.15E-04 2.57E-04 2.11E-04 4.76E-04 6.10E-04 0-8 hours 2.94E-05 6.41E-05 8.58E-05 1.95E-04 1.59E-04 3.64E-04 4.79E-04 8-24 hours 1.36E-05 2.88E-05 3.73E-05 9.53E-05 8.30E-05 1.79E-04 2.33E-04 1-4 days 7.88E-06 1.65E-05 2.17E-05 4.99E-05 4.16E-05 9.14E-05 1.18E-04 4-30 days 5.54E-06 1.18E-05 1.57E-05 3.59E-05 2.85E-05 6.89E-05 8.47E-05 1The location of analyzed Dose Point 4 is actually at the closest point to containment along Segment 4. This point is referred to as Access Point 4 for simplicity.
Table 3-28 Bounding RWST Vent /Q Factors for Control Room Access Dose Analysis Time Period RWST to Access Point 1
/Q (sec/m3)
RWST to Access Point 2
/Q (sec/m3)
RWST to Access Point 3
/Q (sec/m3)
RWST to Access Point 41
/Q (sec/m3)
RWST to Access Point 5
/Q (sec/m3)
RWST to Access Point 6
/Q (sec/m3)
RWST to Access Point 7
/Q (sec/m3) 0-2 hours 3.23E-05 5.44E-05 6.78E-05 1.40E-04 1.36E-04 3.20E-04 3.62E-04 0-8 hours 2.27E-05 4.33E-05 5.39E-05 1.16E-04 1.14E-04 2.81E-04 3.02E-04 8-24 hours 9.19E-06 1.65E-05 2.08E-05 4.59E-05 4.87E-05 1.17E-04 1.27E-04 1-4 days 5.93E-06 1.10E-05 1.35E-05 2.74E-05 2.72E-05 6.56E-05 7.18E-05 4-30 days 4.08E-06 7.02E-06 8.99E-06 1.99E-05 2.04E-05 5.01E-05 5.43E-05 1The location of analyzed Dose Point 4 is actually at the closest point to containment along Segment 4. This point is referred to as Access Point 4 for simplicity.
Enclosure to ULNRC-06787 Page 9 of 19 Table 3-29 Accident Release Sources Accident Transport Path Release Points Limiting Release Point(s)
Fuel Handling Accident Release in Containment Stack Vent Containment Maintenance Hatch Emergency Personnel Access Hatch Containment (Diffuse)
Emergency Personnel Access Hatch (Emergency CR Intake)
Containment (Diffuse)
(Normal CR Intake and TSC)
Release in Fuel Handling Building Stack Vent FHB Closest Point Stack Vent (TSC)
FHB Closest Point (Emergency CR Intake and Normal CR Intake)
Letdown Line Break Release Outside Containment Stack Vent Stack Vent Loss of Coolant Accident Containment Leakage Containment Wall (Diffuse)
Equipment Hatch Stack Vent Containment (Diffuse)
ECCS Leakage Stack Vent Stack Vent RWST Back-Leakage RWST Vent RWST Vent Containment Purge Stack Vent Stack Vent Locked Rotor Primary-to-Secondary Leakage Closest ASD Closest MSSV TDAFP Exhaust Vent Closest ASD (Emergency CR Intake and TSC)
Closest MSSV (Normal CR Intake)
Loss of Non-Emergency AC Power Primary-to-Secondary Leakage Closest ASD Closest MSSV TDAFP Exhaust Vent Closest ASD (Emergency CR Intake and TSC)
Closest MSSV (Normal CR Intake)
Enclosure to ULNRC-06787 Page 10 of 19 Table 3-29 Accident Release Sources Accident Transport Path Release Points Limiting Release Point(s)
Main Steamline Break Primary-to-Secondary Leakage to a Faulted SG Closest ASD Closest Main Steamline Point Closest MSSV TDAFP Exhaust Vent Closest ASD (Emergency CR Intake)
Closest Main Steamline Point (Emergency CR Intake, Normal CR Intake, and TSC)
Closest MSSV (Normal CR Intake)
Steam Generator Tube Rupture Primary-to-Secondary Leakage Closest ASD Closest MSSV TDAFP Exhaust Vent Condenser (Stuck Open ASD Only)
Plant Vent (Stuck Open ASD Only)
Steam Jet Air Ejector (Stuck Open ASD Only)
Closest ASD (Emergency CR Intake and TSC)
Closest MSSV (Normal CR Intake)
Condenser (TSC when Stuck Open ASD)
Rod Ejection Containment Leakage Stack Vent Containment Wall (Diffuse)
Containment Wall (Diffuse)
Primary-to-Secondary Leakage Closest ASD Closest MSSV TDAFP Exhaust Vent Closest ASD (Emergency CR Intake and TSC)
Closest MSSV (Normal CR Intake)
Enclosure to ULNRC-06787 Page 11 of 19 Table 3-30 Control Room /Q Factors for Dose Analysis Time Interval (hours)
/Q (Sec/meters3)
LOCA Containment Leakage, Rod Ejection (Diffuse Containment) 0 - Isolation 7.12E-03 Isolation - 2 7.49E-04 2 - 8 5.32E-04 8 - 24 2.29E-04 24 - 96 1.50E-04 96 - 720 1.02E-04 LOCA Mini-Purge[1] & ECCS Leakage 0 - Isolation (LOCA Mini-Purge &
ECCS Leakage) 1.90E-03 Isolation - 2 6.86E-04 2 - 8 5.72E-04 8 - 24 2.32E-04 24 - 96 1.42E-04 96 - 720 1.00E-04 Letdown Line Break[1] (Unit Vent Exhaust) 0 - 2 1.90E-03 2 - 8 1.58E-03 8 - 24 6.67E-04 24 - 96 3.90E-04 96 - 720 2.65E-04 LOCA RWST Backleakage (RWST Vent) 0 - Isolation 9.28E-04 Isolation - 2 7.47E-04 2 - 8 6.55E-04 8 - 24 2.71E-04 24 - 96 1.52E-04 96 - 720 1.15E-04 FHA in FHB (FHB Closest Point) 0 - Isolation 2.23E-03 Isolation - 2 1.17E-03 2 - 8 1.04E-03 8 - 24 4.27E-04 24 - 96 2.34E-04 96 - 720 1.94E-04 FHA in Containment (Emergency Personnel Access Hatch[2])
0 - Isolation[2]
7.12E-03 Isolation - 2 8.61E-04
Enclosure to ULNRC-06787 Page 12 of 19 Table 3-30 Control Room /Q Factors for Dose Analysis Time Interval (hours)
/Q (Sec/meters3) 2 - 8 7.54E-04 8 - 24 3.22E-04 24 - 96 1.84E-04 96 - 720 1.50E-04 Locked Rotor, SGTR (Closest ASD[3]), Rod Ejection (Closest ASD) 0 - Isolation[3]
1.76E-02 Isolation - 2 1.74E-03 2 - 8 1.33E-03 8 - 24 6.50E-04 24 - 96 3.62E-04 96 - 720 2.96E-04 LOOP[1] (MSSV) 0 - 2 1.76E-02 2 - 8 1.46E-02 8 - 24 6.74E-03 24 - 96 3.81E-03 96 - 720 3.05E-03 MSLB (Closest MSL Point[4])
0 - Isolation[4]
1.76E-02 Isolation - 2[4]
1.74E-03 2 - 8 1.56E-03 8 - 24 6.61E-04 24 - 96 3.83E-04 96 - 720 3.23E-04
[1] In this accident, the control room never isolates, so the normal intake receptor location is used for the entire accident.
[2] Diffuse leakage through the containment wall is used before isolation instead, since it has a higher /Q value.
[3] The closest MSSV is used before isolation instead, since it has a higher /Q value.
[4] The closest MSSV is used before isolation instead, since it has a higher /Q value. Additionally, the closest ASD is used for the first two hours instead, since it has a higher /Q value.
Enclosure to ULNRC-06787 Page 13 of 19 Table 3-32. Fuel Source Term Isotope Core Activity (Ci)
Isotope Core Activity (Ci)
Isotope Core Activity (Ci)
Kr-85 9.677E+05 Cs-134 1.405E+07 Te-125m 1.590E+05 Kr-85m 2.469E+07 Cs-136 4.531E+06 Te-133m 9.382E+07 Kr-87 4.866E+07 Cs-137 1.008E+07 Ba-141 1.587E+08 Kr-88 6.507E+07 Ba-139 1.807E+08 Ba-137m 9.583E+06 Rb-86 1.834E+05 Ba-140 1.715E+08 Pd-109 3.214E+07 Sr-89 9.252E+07 La-140 1.777E+08 Rh-106 5.544E+07 Sr-90 7.220E+06 La-141 1.594E+08 Rh-103m 1.540E+08 Sr-91 1.151E+08 La-142 1.515E+08 Tc-101 1.680E+08 Sr-92 1.235E+08 Ce-141 1.620E+08 Eu-154 5.726E+05 Y-90 7.816E+06 Ce-143 1.492E+08 Eu-155 2.368E+05 Y-91 1.214E+08 Ce-144 1.213E+08 Eu-156 2.182E+07 Y-92 1.250E+08 Pr-143 1.460E+08 La-143 1.475E+08 Y-93 1.416E+08 Nd-147 6.421E+07 Nb-97 1.662E+08 Zr-95 1.651E+08 Np-239 1.907E+09 Nb-95m 1.894E+06 Zr-97 1.651E+08 Pu-238 2.539E+05 Pm-147 1.575E+07 Nb-95 1.659E+08 Pu-239 2.836E+04 Pm-148 1.720E+07 Mo-99 1.811E+08 Pu-240 3.890E+04 Pm-149 5.969E+07 Tc-99m 1.603E+08 Pu-241 1.171E+07 Pm-151 1.881E+07 Ru-103 1.541E+08 Am-241 1.130E+04 Pm-148m 3.619E+06 Ru-105 1.080E+08 Cm-242 3.128E+06 Pr-144 1.222E+08 Ru-106 4.835E+07 Cm-244 2.900E+05 Pr-144m 1.699E+06 Rh-105 9.707E+07 I-130 1.809E+06 Sm-153 4.468E+07 Sb-127 8.907E+06 Kr-83m 1.164E+07 Y-94 1.493E+08 Sb-129 2.816E+07 Xe-138 1.697E+08 Y-95 1.591E+08 Te-127 8.717E+06 Xe-131m 1.280E+06 Y-91m 6.664E+07 Te-127m 1.443E+06 Xe-133m 6.204E+06 Br-82 3.049E+05 Te-129 2.590E+07 Xe-135m 4.176E+07 Br-83 1.154E+07 Te-129m 4.971E+06 Cs-138 1.785E+08 Br-84 2.094E+07 Te-131m 1.886E+07 Cs-134m 4.054E+06 Am-242 6.242E+06 Te-132 1.390E+08 Rb-88 6.626E+07 Np-238 3.962E+07 I-131 9.758E+07 Rb-89 8.706E+07 Pu-243 4.014E+07 I-132 1.414E+08 Sb-124 7.037E+04 I-133 1.996E+08 Sb-125 7.418E+05 I-134 2.240E+08 Sb-126 4.691E+04 I-135 1.893E+08 Te-131 8.272E+07 Xe-133 1.995E+08 Te-133 1.0710E+08 Xe-135 4.704E+07 Te-134 1.772E+08
Enclosure to ULNRC-06787 Page 14 of 19 3.3.2.5 Dose Due to Control Room Access During the 30-day period following a LOCA event, operators will routinely enter and leave the Control Building as shifts change. As these operators walk from the parking lot to the Control Building, they receive a CR access dose due to the activity released from containment. Although numerous AST license amendments have historically been approved without specific analysis to quantify this dose contribution, recent NRC reviews have required a specific assessment with the most recent approvals adding the requirement to assess the CR access dose contribution from ground deposition. Reg Guide 1.183 provides no guidance relative to the methodology or assumptions for assessment of Control Room operator transit/access dose. Furthermore, the NRC has issued no supplemental guidance to assist licensees in developing appropriate methodologies to address this issue. Therefore, the methodologies and assumptions employed herein are based upon engineering judgment to determine an acceptable analysis as interpreted by the various recent NRC actions and interactions on similar AST submittals available through the limited public record.
Each operators access dose is comprised of four components - inhalation dose, immersion/cloudshine dose, containment shine dose and shine dose from deposition of released activity on the ground. The four RADTRAD-NAI models defined for LOCA are used to determine the inhalation and immersion doses along the path from all four sources (containment leakage, ECCS leakage, RWST back-leakage, and containment mini-purge).
Two of the MicroShield models discussed in Section 3.3.2.4.1 (containment shine at 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />) are used to determine the containment shine contribution to the operator access dose. These models are modified to remove the CR wall as shielding and update the buildup material to be the containment wall.
The assessment of the ground deposition contribution uses a slight augmentation of the RADTRAD-NAI models in order to determine the airborne activity concentration at various points along the access path at a number of times during the course of the event for each of the LOCA sub-cases. This airborne activity output from the RADTRAD-NAI cases is then post-processed via spreadsheets using assumed deposition velocities to assess the activity deposited along the access path and its associated dose rate.
The cumulative inhalation, immersion, and containment shine access dose for a single operator over the 30-day period using the defined method is thus 0.57 rem TEDE. Combined with the ground deposition dose of 0.27 rem TEDE, the total access dose for a single operator over the 30-day period following a LOCA event is 0.84 rem TEDE.
Enclosure to ULNRC-06787 Page 15 of 19 3.3.6.2.3.2 Primary-to-Secondary Leakage Release For the primary-to-secondary leakage case, where the RCS is assumed to be intact, there is no SI signal generated; however, the control room intake radiation monitor signal setpoint is reached in the analysis.
Since the analysis assumes no delay in the release of activity and no delays in the transport of activity through the primary and secondary systems or in the transport from the release point to the air intake, the activity concentration at the detector immediately following event initiation, 3 seconds, is 7.1E-3 Ci/cc Xe-133. The analysis models a detector setpoint of 2.2E-3 Ci/cc Xe-133. Therefore, an instantaneous generation of the high radiation signal could be assumed. As a result, the control room ventilation system enters emergency mode operation 120 seconds into the event, which includes a 60-second delay from the control room air intake monitor initiating signal and an additional 60 seconds of margin. As discussed in Section 3.3.2.1, operator action is taken 30 minutes after control room isolation to isolate the ventilation train with failed filtration.
3.3.6.4 Results and Conclusions The rod ejection accident doses are listed below:
For the containment leakage case:
EAB 1.43 rem TEDE LPZ 3.24 rem TEDE Control room 4.09 rem TEDE TSC 1.56 rem TEDE For the primary-to-secondary leakage case:
EAB 1.34 rem TEDE LPZ 7.2E-01 rem TEDE Control room 4.13 rem TEDE TSC 4.3E-01 rem TEDE
Enclosure to ULNRC-06787 Page 16 of 19 3.3.8.1.5 Control Room The control room intake radiation monitor signal setpoint is reached in the analysis. Since the analysis assumes no delay in the release of activity and no delays in the transport of activity through the primary and secondary systems or in the transport from the release point to the air intake, the activity concentration at the detector immediately following event initiation, 3 seconds, is 9.51E-3 Ci/cc Xe-133.
The analysis models a detector setpoint of 2.2E-3 Ci/cc Xe-133. Therefore, an instantaneous generation of the high radiation signal could be assumed.
As a result, the Control Building and Control Room HVAC enters the emergency mode of operation 120 seconds into the accident, which includes the 60 seconds for the Control Room to isolate and an additional 60 seconds of margin.
Operator action is taken after 30 minutes to remedy the half-train failure in the Control Building/Control Room Emergency HVAC to isolate the ventilation train with failed filtration.
Enclosure to ULNRC-06787 Page 17 of 19 3.3.9.2.3 Control Room In the event of a LOCA, the low pressurizer pressure SI setpoint will be reached almost immediately following the break. The SI signal causes the control room to switch from the normal operation mode to the emergency operation mode. The switch is conservatively modeled at 62 seconds following event initiation, which includes a 60-second delay from the initiating signal. As discussed in Section 3.3.2.1, operator action is taken after 30 minutes to remedy the half-train failure in the Control Building/Control Room Emergency HVAC to isolate the ventilation train with failed filtration.
As discussed in Section 3.3.2.4.1, the dose to control room personnel from external sources was calculated to be 0.012 rem TEDE. These external sources include the activity remaining in containment following the LOCA, the activity cloud outside of the control room in the environment, and the activity buildup on recirculation filters. This is added to the dose calculated from the four release paths discussed above.
As discussed in Section 3.3.2.5, the dose to control room personnel due to transit to and from the control room was calculated to be 0.84 rem TEDE. The transit dose includes contributions from inhalation, immersion, and shine from ground deposition along the operators path between the control room and the parking lot. This is added to the dose calculated from the four release paths discussed above.
Note that the assumed iodine chemical fractions for the containment purge pathway do not impact the analysis results since neither spray nor filtration is credited for removal of the RCS activity in the release path. Also, since control room isolation does not occur until after mini-purge is isolated, no filtration of air flow to the control room is modeled.
3.3.9.4 Results and Conclusions The following summarizes the doses for each pathway analyzed for the LOCA dose consequence analysis:
EAB Containment Leakage 4.60 rem TEDE ECCS Leakage 0.88 rem TEDE RWST Back-Leakage 0.15 rem TEDE Containment Purge 7.0E-03 rem TEDE LPZ Containment Leakage 2.96 rem TEDE ECCS Leakage 2.18 rem TEDE RWST Back-Leakage 1.10 rem TEDE Containment Purge 2.4E-03 rem TEDE
Enclosure to ULNRC-06787 Page 18 of 19 Control Room Containment Leakage 1.34 rem TEDE ECCS Leakage 1.31 rem TEDE RWST Back-Leakage 7.1E-01 rem TEDE Containment Purge 1.5E-01 rem TEDE External Shine 1.2E-02 rem TEDE CR Access Dose 0.84 rem TEDE TSC Containment Leakage 1.02 rem TEDE ECCS Leakage 0.85 rem TEDE RWST Back-Leakage 2.2E-01 rem TEDE Containment Purge 1.2E-03 rem TEDE External Shine 7.2E-03 rem TEDE The total LOCA doses from all of the pathways are listed below:
EAB 5.64 rem TEDE LPZ 6.24 rem TEDE Control room 4.36 rem TEDE TSC 2.10 rem TEDE
Enclosure to ULNRC-06787 Page 19 of 19 3.3.10.2.3 Control Room FHA_FHB Technical Specifications do not require the radiation monitors at the control room air intakes to be operable during movement of irradiated fuel assemblies in the fuel building. Instead, the High gaseous Fuel Building Exhaust Radiation channels GG-RE-27 and GG-RE-28 actuate both the Emergency Exhaust System (EES) and control room isolation. For these channels the Hi Alarm setpoint is 3.2E-3
µCi/cc Xe-133.
The High gaseous Fuel Building Exhaust Radiation Hi setpoint is reached in the analysis. Since the analysis assumes no delay in the release of activity and no delays in the transport from the release point to the detector, the Xe-133 activity concentration at the detector immediately following event initiation (72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after shutdown) is 0.63 Ci/cc. This value is over 3 orders of magnitude greater than the setpoint.
Therefore, an instantaneous generation of the high radiation signal could be assumed.
However, control room isolation is assumed to occur 120 seconds after event initiation; a 60-second delay is allowed for the detector to reach its setpoint and an additional 60 seconds is allowed for control room isolation once the setpoint has been reached.
Operator action is taken after 30 minutes to remedy the half-train failure in the Control Building/Control Room Emergency HVAC to isolate the ventilation train with failed filtration.
FHA_RCB The control room intake radiation monitor signal setpoint is reached in the analysis. Since the analysis assumes no delay in the release of activity and no delays in the transport of activity through the primary and secondary systems or in the transport from the release point to the air intake, the activity concentration at the detector immediately following event initiation, 3 seconds, is 9.66E-2 Ci/cc Xe-133.
The analysis models a detector setpoint of 2.2E-3 Ci/cc Xe-133. Therefore, an instantaneous generation of the high radiation signal could be assumed.
However, control room isolation is assumed to occur 120 seconds after event initiation; a 60-second delay is allowed for the detector to reach its setpoint and an additional 60 seconds is allowed for control room isolation once the setpoint has been reached.
Operator action is taken after 30 minutes to remedy the half-train failure in the Control Building/Control Room Emergency HVAC to isolate the ventilation train with failed filtration.