NG-13-0182, Response to Request for Additional Information, License Amendment Request to Adopt National Fire Protection Association Standard 805, Performance-Based Standard for Fire Protection for Light Water Reactor Generating Plants
| ML13122A045 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 05/01/2013 |
| From: | Richard Anderson NextEra Energy Duane Arnold |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NG-13-0182 | |
| Download: ML13122A045 (27) | |
Text
May 1, 2013 NEXTeraM ENERGY
DUANE ARNOLD NG-13-0182 10 CFR 50.90 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Duane Arnold Energy Center Docket No. 50-331 Renewed Op. License No. DPR-49 Response to Request for Additional Information, License Amendment Request to Adopt National Fire Protection Association Standard 805, Performance-Based Standard For Fire Protection For Light Water Reactor Generating Plants
References:
- 1) License Amendment Request (TSCR-128): Transition to 10 CFR 50.48(c) - NFPA 805, Performance-Based Standard For Fire Protection For Light Water Reactor Generating Plants (2001 Edition), NG-11-0267, dated August 5, 2011 (ML11221A280)
- 2) Clarification of Information Contained in License Amendment Request (TSCR-128): Transition to 10 CFR 50.48(c) - NFPA 805, Performance-Based Standard For Fire Protection For Light Water Reactor Generating Plants (2001 Edition), NG-11-0384, dated October 14, 2011
- 3) Response to Request for Additional Information, License Amendment Request to Adopt National Fire Protection Association Standard 805, Performance-Based Standard For Fire Protection For Light Water Reactor Generating Plants, NG 0056, dated February 12, 2013 (ML13046A031)
- 4) Response to Request for Additional Information, License Amendment Request to Adopt National Fire Protection Association Standard 805, Performance-Based Standard For Fire Protection For Light Water Reactor Generating Plants, NG 1 02, dated March 6, 2013 (ML13070A065)
- 5) Electronic Communication, ME6818 - DAEC Adoption of NFPA-805 - Request for Additional Information (revised), dated April 4, 2013 (ML13098B072)
In the Reference 1 letter, as clarified by Reference 2, NextEra Energy Duane Arnold, LLC (hereafter NextEra Energy Duane Arnold) submitted a License NextEra Energy Duane Arnold, LLC, 3277 DAEC Road, Palo, lA 52324
Document Control Desk NG-13-0182 Page 2 of 2 Amendment Request for the Duane Arnold Energy Center (DAEC) pursuant to 10 CFR 50.90. Subsequently, the NRC Staff requested, via Reference 5, additional information regarding that application. The Attachment to this letter contains the requested information.
This additional information does not impact the 10 CFR 50.92 evaluation of "No Significant Hazards Consideration" previously provided in the referenced application.
Reference 1 discusses, in Table 4-3 and Attachments C, S and W, installation of an incipient detection modification. Subsequently, reference to that commitment appeared in RAI PRA 78 of Reference 3 and was clarified in the cover letter and attached response to RAI SSA 1.01 of Reference 4. That commitment, to design and install an incipient detection modification, is hereby retracted. This letter makes no new commitments.
If you have any questions or require additional information, please contact Tom Byrne at 319-851-7929.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on May 1, 2013 Tc/.} ()
Richard L. Ande
Vice President, Duane Arnold Energy Center NextEra Energy Duane Arnold, LLC
Attachment:
Response to Request for Additional Information, License Amendment Request to Adopt National Fire Protection Association Standard 805, Performance-Based Standard For Fire Protection For Light Water Reactor Generating Plants cc:
M. Rasmusson (State of Iowa)
24 pages follow Attachment to NG-13-0182 Response to Request for Additional Information, License Amendment Request to Adopt National Fire Protection Association Standard 805, Performance-Based Standard For Fire Protection For Light Water Reactor Generating Plants
Page 1 of 22 DAEC RAI PRA 82 The NRC staff identified numerous methods that were used in the fire probabilistic risk assessment (FPRA) that have not yet been accepted by the staff. Requests for Additional Information (RAIs) were provided (January 31, 2012 Agencywide Document Access and Management System (ADAMS) Accession No. ML12031A112, October 26, 2012 ADAMS Accession No. ML12304A069, and December 5, 2012, ADAMS Accession No. ML12340A450) about these methods and the responses (April 23, 2012, ADAMS Accession No. ML12117A052, May 23, 2012, ADAMS Accession No. ML12146A094, February 12, 2013, ADAMS Accession No. ML13046A031, and March 6, 2013 (ADAMS Accession No. ML13070A065) have been reviewed.
RAIs have identified the method differences from NUREG/CR 6850 or FAQs. Some RAI responses describe that the method differences have been addressed to be consistent with acceptable methods. For other RAIs, the staff has determined that additional information is needed. An integrated analysis is being requested for all of these methods, as discussed below:
Regarding determining the HRR of transient fires that differ from those endorsed by the NRC in its letter to NEI dated June 21, 2012 on Recent Fire PRA Methods Review Panel Decisions and EPRI 1022993, Evaluation of Peak Heat Release Rates in Electrical Cabinet Fires (ADAMS Accession No. ML12171A583). (PRA RAI 01.01c)
Regarding the need to sum all barrier elements in the multi-compartment analysis. (PRA RAI 05)
Regarding the use of an emergency diesel generator aggressive fire factor. (PRA RAI 07)
Regarding turbine generator ignition frequency and credit for manual suppression. (PRA RAI 11.01)
Regarding the use of excessive Control Power Transformer (CPT) credit. (PRA RAI 12)
Regarding removal of the hot-work pre-initiator factor of 0.01 for hot work administrative controls. (PRA RAI 14a)
Regarding the use of a Very Low transient influence factor in the frequency factors for distributing transient frequency. (PRA RAI 14b)
Regarding the use of a minimum non-suppression probability of less than 0.001.
Regarding not following NUREG/6850 Step 5.c (Section 11.5.4.5) while determining the extent of fire damage during MCA. (PRA RAI 08.01)
Regarding crediting prompt (i.e., hot work type) suppression for transient fires.
Regarding credit given to sealed electrical cabinets to prevent fire spread. (PRA RAI 70)
Regarding the credit for incipient detection in the main control room. The staff and industry have not completed the FAQ on incipient detection in the main
Page 2 of 22 control room. A sensitivity study is requested for the integrated analysis with no credit for incipient detection in the main control room until an acceptable method is completed. In addition, you may provide and evaluate a proposed method.
Regarding modeling of sensitive electronics in cabinet using cable damage criteria instead of sensitive electronics criteria. The response discussed the main control room only; however, any application of this method for sensitive electronics outside the main control room should also be considered in the integrated analysis. In addition, please discuss the assumptions, approach, and analyses applied to the Fire PRA for sensitive electronics outside the main control room. (PRA RAI 69)
Regarding the use a conditional probability of 0.1. The response does not provide adequate justification for the use of the conditional probability of 0.1.
Either provide additional justification or remove the 0.1 credit in the integrated analysis. (PRA RAI 71)
Regarding a sensitivity study for the transient HRR if it differs from NUREG/CR-6850 guidance. If it is determined to differ, include it in the integrated analysis.
In addition, the data collection effort on identification of which cables are thermoplastic and which are unqualified should be incorporated into the Fire PRA as appropriate for this integrated analysis. (FM RAI 02 response)
The following information is requested for the methods discussed above:
- a. Results of a composite analysis that shows the integrated impact on the fire risk (Core Damage Frequency (CDF), Large Early Release Frequency (LERF), delta
()CDF, and LERF) of all of the above method changes analyses. In this composite analysis, for those cases where the individual issues have a synergistic impact on the results, perform a simultaneous analysis. For those cases where no synergy exists, perform a one-at-a-time analysis. In the response, provide justification of how the Regulatory Guide 1.174, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis, risk acceptance guidelines are satisfied for the composite analysis of all the issues identified and, if applicable, a description of any new modifications or operator actions being credited to reduce delta risk and the associated impacts of the fire protection program.
- b. An additional composite analysis that includes only the analyses believed to be appropriate and justification for not using selected methods. Include justification of how the RG 1.174 risk acceptance guidelines are satisfied.
RESPONSE
A response to each of the identified RAIs in this RAI PRA 82 was provided in which the analysis was revised, justification provided, or the results of a sensitivity study was provided. These analyses performed in support of these RAI responses were utilized in the composite analyses requested in this RAI. In response to this RAI, the results of two analyses are provided:
Page 3 of 22
- 1) A composite analysis that includes revised treatments from the identified RAIs in the PRA and the sensitivity studies from the identified RAIs
- 2) A composite analysis that includes revised treatments from the identified RAIs in the PRA without the sensitivity studies The treatment of each identified RAI in the composite analyses is summarized below.
Page 4 of 22 PRA RAI Treatment in the Fire PRA RAI Response Reflected in Part A RAI Response Reflected in Part B 01.01c The RAI response dated March 6, 2013, provided the results of a sensitivity study using the NUREG/CR-6850 transient HRR of 317 kW. The results of the sensitivity study are included in the composite sensitivity analysis. At the time of the LAR submittal, guidance for justification of HRRs different than NUREG/CR-6850 guidance was in review. In lieu of incorporating the guidance that was eventually accepted, a sensitivity study has been provided and estimates a small change in the fire PRA CDF and LERF and the delta CDF and delta LERF.
Yes No 05 The RAI response dated May 23, 2012, included a revised MCA in which barrier elements were summed.
The revised MCA is included in the composite analysis.
Yes Yes 07 The RAI response dated May 23, 2012, included a revised analysis without the factor. The revised analysis is included in the composite analysis.
Yes Yes 11.01 The RAI response dated March 6, 2013, included a revised analysis without manual suppression credit.
The revised analysis is included in the composite analysis.
Yes Yes 12 The RAI response dated May 23, 2012, provided the results of a sensitivity study removing CPT credit.
The results of the sensitivity study are included in the composite sensitivity analysis. Currently, NUREG/CR-6850 is the only available guidance for applying circuit failure mode probabilities.
Yes No 14a The response to PRA RAI 14.01 dated February 12, 2013, included a revised CSR analysis without use of the factor. The revised analysis is included in the composite analysis.
Yes Yes 14b The response to PRA RAI 14.01 dated February 12, 2013, included a revised CSR analysis with the use of the Very Low ranking consistent with new FAQ 12-0064. The revised analysis is included in the composite analysis.
Yes Yes 72 The RAI response dated March 6, 2013, included revised analysis to use a minimum non-suppression probability of 0.001. The revised analysis is included in the composite analysis.
Yes Yes 08.01 The RAI response dated March 6, 2013, included a revised MCA to include NUREG/CR-6850 Step 5.c (Section 11.5.4.5) while determining the extent of fire damage during MCA. The revised analysis is included in the composite analysis.
Yes Yes 14.01d The response to PRA RAI 14.01 dated February 12, 2013, included a revised CSR analysis with credit for prompt suppression only for hot work fires. The revised analysis is included in the composite analysis.
Yes Yes 70 The RAI response dated February 12, 2013, identified that the credit given to sealed electrical cabinets to prevent fire spread was consistent with the treatment in FAQ 08-0042.
Yes Yes 35.01 The RAI response dated March 6, 2013, included justification for incipient detection credit and the results of a sensitivity without incipient detection credit. No credit for incipient detection is included in the composite analysis.
No No
Page 5 of 22 PRA RAI Treatment in the Fire PRA RAI Response Reflected in Part A RAI Response Reflected in Part B 69 In response to this RAI, an evaluation of electronics outside the Main Control Room was performed. The results of the evaluation are included in the composite analysis.
The sites Electrolytic Capacitor Database was reviewed for equipment and equipment types that contain electrolytic capacitors on the basis that components with electrolytic capacitors are most likely to contain electronics that may have a lower damage threshold than cables. Electrolytic capacitors are used in the power supplies for transistors and integrated circuits. There is not yet a clear industry definition for electronics that have a lower damage threshold as identified by NUREG/CR-6850 Section H.2; therefore, any component that could contain semi-conductors, resistors, capacitors (electrolytic or ceramic), or similar solid-state components were included.
The fire PRA and NSCA equipment lists were reviewed to identify equipment that may contain electronics or be part of a loop of components that contain electronics.
Components that are part of the Alternate Shutdown Capability system are not included. These components require transfer for use and are only credited for Main Control Room abandonment scenarios.
Based on these criteria, components with electronics outside the Main Control Room were selected.
Walkdowns were performed to identify ignition sources that may result in fire damage to these components. NUREG/CR-6850 Section H.2 was used in determining the threshold damage temperature.
The fire PRA was updated to reflect the additional component failures.
Refer to Appendix G of report 0493080001.006, Rev. 2, for more details regarding the treatment of electronics outside the Main Control Room.
Yes Yes 71 In response to this RAI, the conditional probability was removed. The revised analysis is included in the composite analysis.
Yes Yes 83b In response to the RAI, it was clarified that the HRR used in the updated CSR analysis was based on NUREG/CR-6850 guidance. The revised analysis is included in the composite analysis.
Yes Yes FM RAI 02 In response to the RAI dated October 15, 2012, an evaluation of unqualified and thermoplastic cables was performed. The results of the evaluation are included in the composite analysis.
Yes Yes
Page 6 of 22
- a. A composite analysis was performed to include the acceptable revised treatments from the identified RAI responses summarized above and the results of the requested sensitivity studies provided in RAI responses PRA RAI 01.01c and PRA RAI 12. The simultaneous composite analysis includes the synergistic effect of each of the treatments. Table 1 presents the results of the analysis. Given these results, the risk acceptance guidelines of RG 1.174 are satisfied. No new modifications or operator actions are required.
Table 1 Composite Sensitivity Analysis Results Risk Metric Fire Risk (/yr)
Fire Risk (/yr)
CDF 3.04E-5 (1,3) 1.33E-7 (2)
LERF 9.39E-6 (1,3) 8.44E-8 (2)
Notes to Table 1:
- 1.
Presented results include the fire ignition frequencies (FIFs) from FAQ 08-0048 and are calculated using the ACUBE software. The following table presents the calculated results with NUREG/CR-6850 FIFs using the FRANC software.
Model CDF (/yr)
LERF (/yr)
NUREG/CR-6850 FIFs FRANC Calculation 4.89E-5 1.65E-5 FAQ 08-0048 FIFs FRANC Calculation 3.30E-5 1.19E-5
- 2.
The Fire Risk Calculations were performed using NUREG/CR-6850 FIFs and using the FRANC software.
- 3.
The CSR evaluation in report 0493080001.007 identified several refinements in the late alternate injection model that will result in an estimated 9% decrease in CDF and 13% decrease in LERF when applied to the base model. Additionally, Section 8.6 of the quantification report (0493080001.004, Rev. 3) identified potential risk decrease from Section B.5.b of Commission Order EA-02-026 strategies that could decrease the estimated LERF by 25% when implemented into the model. The results in Table 1 do not reflect these additional refinements.
- b. A composite analysis was performed to include the acceptable revised treatments from the identified RAI responses summarized above without the results of the requested sensitivity studies provided in RAI responses PRA RAI 01.01c and PRA RAI 12. The simultaneous composite analysis includes the synergistic effect of each of the treatments. Table 2 presents the results of the analysis. Given these results, the risk acceptance guidelines of RG 1.174 are satisfied. No new modifications or operator actions are required.
Table 2 Composite Analysis Results Risk Metric Fire Risk (/yr)
Fire Risk (/yr)
CDF 3.01E-5 (1,3) 1.26E-7 (2)
LERF 9.23E-6 (1,3) 8.14E-8 (2)
Notes to Table 2:
- 1.
Presented results include the FIFs from FAQ 08-0048 and are calculated using the ACUBE software. The following table presents the calculated results with NUREG/CR-6850 FIFs using the FRANC software.
Page 7 of 22 Model CDF (/yr)
LERF (/yr)
NUREG/CR-6850 FIFs FRANC Calculation 4.86E-5 1.64E-5 FAQ 08-0048 FIFs FRANC Calculation 3.29E-5 1.18E-5
- 2.
The Fire Risk Calculations were performed using NUREG/CR-6850 FIFs and using the FRANC software.
- 3.
The CSR evaluation in report 0493080001.007 identified several refinements in the late alternate injection model that will result in an estimated 9% decrease in CDF and 13% decrease in LERF when applied to the base model. Additionally, Section 8.6 of the quantification report (0493080001.004, Rev. 3) identified potential risk decrease from Section B.5.b of Commission Order EA-02-026 strategies that could decrease the estimated LERF by 25% when implemented into the model. The results in Table 2 do not reflect these additional refinements.
Consistent with the information provided in Attachment W of the LAR, the risk change due to the NFPA 805 transition meets the acceptance guidelines of RG 1.205. RG 1.205 requires that the total risk increase should be consistent with the acceptance guidelines in RG 1.174.
The total increase in CDF for this application is calculated to be 1.26E-07/yr and the total increase in LERF is calculated to be 8.14E-08/yr; these meet the RG 1.174 criteria.
RG 1.174 classifies an increase in CDF of less than 1E-06/yr and an increase in LERF of less than 1E-07/yr as very small and allows the change to be considered regardless of whether there is a calculation of total CDF or LERF if these criteria are met.
Although RG 1.174 does not require calculation of total CDF and LERF if the increases are below the delta CDF and delta LERF of 1E-06/yr and 1E-07/yr respectively, it does recommend that if there is an indication that the CDF is considerably higher than 1E-04/yr or if LERF is considerably higher than 1E-05/yr then the focus should be on finding ways to decrease rather that increase CDF or LERF.
For this application the total CDF has a value below the 1E-04/yr criteria. LERF has a value which is not considerably higher than the 1E-05/yr criteria. Furthermore, there are additional conservatisms that were not considered in the Fire PRA model that if applied would significantly reduce LERF. These conservatisms are identified in the footnotes to Table 1 and Table 2.
LAR Attachment W replacement tables are provided as Tables 3 - 6 of this RAI response. These tables reflect the composite effects of the RAI response and also supersede LER attachment W tables provided in the RAI response dated May 23, 2012.
Page 8 of 22 Table 3 Summary of Risk Significant CDF Fire Scenarios (CDF Contribution > 1.0%)
(LAR Table W-1 Replacement)
Scenario Description Contribution(1)
Risk Insights FIF(1)
CCDP(1)
(/yr)(1) 10F F40 1A3 - 4160V HEAF - Cub. 301-302 8.6%
Fire scenario 10F F40 is a high energy arching fault fire at the 1A3 essential switchgear that is postulated to damage the adjacent cubicles and the cable tray above. The scenario results in a loss of offsite power given damage to the 1X3 and 1X4 protective relaying cables. 1A4 Essential switchgear is unavailable due to the loss of offsite power coupled with maintenance or random failures of the Standby Diesel Generator 1G21. Offsite power recovery is not credited given the fire damage.
5.88E-05 7.13E-02 4.19E-06 10E F56 1A4 - HEAF - Cub. 401-402 8.2%
Fire scenario 10E F56 is a high energy arching fault fire at the 1A4 essential switchgear that is postulated to damage the adjacent cubicles and the cable tray above. The scenario results in a loss of offsite power given damage to the 1X3 and 1X4 protective relaying cables. 1A3 Essential switchgear is unavailable due to the loss of offsite power coupled with maintenance or random failures of the Standby Diesel Generator 1G31. Offsite power recovery is not credited given the fire damage.
5.88E-05 6.79E-02 3.99E-06 10F F14 1B3 - 480V LC Fire - Target Damage 5.1%
Fire scenario 10F F14 is a fire at the 1B3 480V Load Center which is postulated to damage cables in the 98th percentile heat release rate zone of influence. The scenario results in general transient accident sequences with a complete loss of Division 1 equipment coupled with maintenance or random failure of Division 2 equipment.
2.14E-04 3.45E-02 2.50E-06 12A F66 1C-31 Electrical Panel - Loss of 1A3 5.0%
Fire scenario 12A F66 is a panel fire in the MG & Plant Relay Cabinet isolated to Division 1. The scenario results in the loss of offsite power and the 1A3 Essential Switchgear from postulated fire damage. 1A4 Essential switchgear is unavailable due to the loss of offsite power coupled with maintenance or random failures of the Standby Diesel Generator 1G21. Offsite power recovery is not credited given the fire damage.
1.42E-04 7.13E-02 2.44E-06
Page 9 of 22 Table 3 Summary of Risk Significant CDF Fire Scenarios (CDF Contribution > 1.0%)
(LAR Table W-1 Replacement)
Scenario Description Contribution(1)
Risk Insights FIF(1)
CCDP(1)
(/yr)(1) 10E F01 1D44 - BC Fire - Target Damage -
Full ZOI 4.9%
Fire scenario 10E F01 is a fire at the 1D44 battery charger which is postulated to damage cables in the 98th percentile heat release rate zone of influence. The scenario results in a loss of offsite power given damage to the 1X3 and 1X4 protective relaying cables. 1A3 Essential switchgear is unavailable due to the loss of offsite power coupled with maintenance or random failures of the Standby Diesel Generator 1G31. Offsite power recovery is not credited given the fire damage. Additionally, HPCI and RCIC are unavailable given fire damage to cables.
1.90E-04 7.36E-02 2.38E-06 12A F67 1C-31 Electrical Panel - Loss of 1A4 4.8%
Fire scenario 12A F67 is a panel fire in the MG & Plant Relay Cabinet isolated to Division 2. The scenario results in the loss of offsite power and the 1A4 Essential Switchgear from postulated fire damage. 1A3 Essential switchgear is unavailable due to the loss of offsite power coupled with maintenance or random failures of the Standby Diesel Generator 1G31. Offsite power recovery is not credited given the fire damage.
1.42E-04 6.78E-02 2.32E-06 11A CDF CSR - CDF 2.6%
Fire scenario 11A CDF is a surrogate for the postulated fire scenarios in the Cable Spreading Room. Refer to report 0493080001.007 for details of the postulated fire scenarios.
The FIF presented in this table is a surrogate for the estimated Cable Spreading Room CDF.
1.26E-06 1.00E+00 1.26E-06 10E F76 1D44 - BC Fire - Target Damage -
First Set 2.2%
Fire scenario 10E F76 is a fire at the 1D44 battery charger which is postulated to damage cables in the first overhead cable tray. The scenario results in a loss of offsite power given damage to the 1X3 and 1X4 protective relaying cables. 1A3 Essential switchgear is unavailable due to the loss of offsite power coupled with maintenance or random failures of the Standby Diesel Generator 1G31. Offsite power recovery is not credited given the fire damage.
1.90E-04 7.07E-02 1.07E-06
Page 10 of 22 Table 3 Summary of Risk Significant CDF Fire Scenarios (CDF Contribution > 1.0%)
(LAR Table W-1 Replacement)
Scenario Description Contribution(1)
Risk Insights FIF(1)
CCDP(1)
(/yr)(1) 10E F46 1B4 - 480V LC Fire - Target Damage 1.7%
Fire scenario 10E F46 is a fire at the 1B4 load center which is postulated to damage targets in the 98th percentile heat release rate zone of influence. Fire induced damage results in loss of Division 2 equipment. Dominate sequences include loss of room cooling scenarios. Additionally, the MSIVs have target cables in the scenario and operator failure to manually close the MSIVs from the MCR is postulated to result in a large steam LOCA.
2.14E-04 1.15E-02 8.33E-07 10F F12 1A3 Cub. 312 - 4160V SWGR Fire -
Target Damage 1.6%
Fire scenario 10F F12 is a panel fire at the 1A3 essential switchgear cubicle 312 that is postulated to damage the adjacent cubicles and the cable tray above. The scenario results in a loss of offsite power given damage to the 1X3 and 1X4 protective relaying cables. 1A4 Essential switchgear is unavailable due to the loss of offsite power coupled with maintenance or random failures of the Standby Diesel Generator 1G21. Offsite power recovery is not credited given the fire damage. Additionally, HPCI and RCIC are unavailable because of cables postulated to be damaged.
7.09E-05 7.86E-02 7.81E-07 10E F05 1XL80 - XFMR Fire - Target Damage 1.6%
Fire scenario 10E F05 is a fire at the 1XL80 transformer that damages the cables in the above trays. The scenario results in general transient accident sequences with complete loss of Division 2 equipment coupled with maintenance or random failure of Division 1 equipment.
2.19E-04 7.40E-03 7.61E-07 10F F01 1A3 Cub. 301 - 4160V SWGR Fire -
Target Damage 1.5%
Fire scenario 10F F01 is a panel fire at the 1A3 essential switchgear cubicle 301 that is postulated to damage the adjacent cubicles and the cable tray above. The scenario results in a loss of offsite power given damage to the 1X3 and 1X4 protective relaying cables. 1A4 Essential switchgear is unavailable due to the loss of offsite power coupled with maintenance or random failures of the Standby Diesel Generator 1G21. Offsite power recovery is not credited given the fire damage.
7.09E-05 7.20E-02 7.15E-07
Page 11 of 22 Table 3 Summary of Risk Significant CDF Fire Scenarios (CDF Contribution > 1.0%)
(LAR Table W-1 Replacement)
Scenario Description Contribution(1)
Risk Insights FIF(1)
CCDP(1)
(/yr)(1) 10F F02 1A3 Cub. 302 - 4160V SWGR Fire -
Target Damage 1.5%
Fire scenario 10F F02 is a panel fire at the 1A3 essential switchgear cubicle 302 that is postulated to damage the adjacent cubicles and the cable tray above. The scenario impacts are similar to scenario 10F F01.
7.09E-05 7.20E-02 7.15E-07 10F F03 1A3 Cub. 303 - 4160V SWGR Fire -
Target Damage 1.5%
Fire scenario 10F F03 is a panel fire at the 1A3 essential switchgear cubicle 303 that is postulated to damage the adjacent cubicles and the cable tray above. The scenario impacts are similar to scenario 10F F01.
7.09E-05 7.20E-02 7.15E-07 10F F38 1A3 - 4160V SWGR Fire - No Target Damage - Cub. 302 1.5%
Fire scenario 10F F38 is a panel fire at the 1A3 essential switchgear cubicle 302 that damages the cables in the cubicle only. The scenario results in general transient accident sequences with fire damage to the Startup Transformer cables and complete loss of Division 1 equipment coupled with maintenance or random failure of Division 2 equipment.
7.12E-05 1.17E-02 7.13E-07 10E F51 1A4 Cub. 401 - 4KV MVSG Fire -
Target Damage 1.5%
Fire scenario 10E F51 is a panel fire at the 1A4 essential switchgear cubicle 401 that is postulated to damage the adjacent cubicles and the cable tray above. The scenario results in a loss of offsite power given damage to the 1X3 and 1X4 protective relaying cables. 1A3 Essential switchgear is unavailable due to the loss of offsite power coupled with maintenance or random failures of the Standby Diesel Generator 1G31. Offsite power recovery is not credited given the fire damage.
7.09E-05 7.17E-02 7.12E-07 10E F77 1A4 Cub. 402 - 4KV MVSG Fire -
Target Damage 1.5%
Fire scenario 10E F77 is a panel fire at the 1A4 essential switchgear cubicle 402 that is postulated to damage the adjacent cubicles and the cable tray above. The scenario impacts are similar to scenario 10E F51.
7.09E-05 7.17E-02 7.12E-07 10F F07 1A3 Cub. 307 - 4160V SWGR Fire -
Target Damage 1.5%
Fire scenario 10F F07 is a panel fire at the 1A3 essential switchgear cubicle 307 that is postulated to damage the adjacent cubicles and the cable tray above. The scenario impacts are similar to scenario 10F F01.
7.09E-05 7.16E-02 7.11E-07
Page 12 of 22 Table 3 Summary of Risk Significant CDF Fire Scenarios (CDF Contribution > 1.0%)
(LAR Table W-1 Replacement)
Scenario Description Contribution(1)
Risk Insights FIF(1)
CCDP(1)
(/yr)(1) 10F F04 1A3 Cub. 304 - 4160V SWGR Fire -
Target Damage 1.5%
Fire scenario 10F F04 is a panel fire at the 1A3 essential switchgear cubicle 304 that is postulated to damage the adjacent cubicles and the cable tray above. The scenario impacts are similar to scenario 10F F01.
7.09E-05 7.13E-02 7.07E-07 10F F05 1A3 Cub. 305 - 4160V SWGR Fire -
Target Damage 1.5%
Fire scenario 10F F05 is a panel fire at the 1A3 essential switchgear cubicle 305 that is postulated to damage the adjacent cubicles and the cable tray above. The scenario impacts are similar to scenario 10F F01.
7.09E-05 7.13E-02 7.07E-07 10F F06 1A3 Cub. 306 - 4160V SWGR Fire -
Target Damage 1.5%
Fire scenario 10F F06 is a panel fire at the 1A3 essential switchgear cubicle 306 that is postulated to damage the adjacent cubicles and the cable tray above. The scenario impacts are similar to scenario 10F F01.
7.09E-05 7.13E-02 7.07E-07 10F F08 1A3 Cub. 308 - 4160V SWGR Fire -
Target Damage 1.5%
Fire scenario 10F F08 is a panel fire at the 1A3 essential switchgear cubicle 308 that is postulated to damage the adjacent cubicles and the cable tray above. The scenario impacts are similar to scenario 10F F01.
7.09E-05 7.13E-02 7.07E-07 10F F09 1A3 Cub. 309 - 4160V SWGR Fire -
Target Damage 1.5%
Fire scenario 10F F09 is a panel fire at the 1A3 essential switchgear cubicle 309 that is postulated to damage the adjacent cubicles and the cable tray above. The scenario impacts are similar to scenario 10F F01.
7.09E-05 7.13E-02 7.07E-07 10F F19 1D43 - BC Fire - Target Damage 1.4%
Fire scenario 10F F19 is a fire at the 1D43 Battery Charger that damages the cables in the 98th percentile heat release rate zone of influence. The scenario results in general transient accident sequences with complete loss of Division 1 equipment coupled with maintenance or random failure of Division 2 equipment.
1.90E-04 7.50E-03 6.70E-07 10E F75 1A4 Cub. 405-412-4KV MVSG Fire
- Target Damage 1.3%
Fire scenario 10E F75 is a fire at the 1A4 essential switchgear that does not result in a fire induced LOOP. Fire induced damage results in loss of Division 2 equipment.
Dominate sequences include loss of room cooling scenarios. The scenario results generally in transient sequences with random failures of Division 1 equipment resulting in core damage.
5.70E-04 7.82E-03 6.24E-07
Page 13 of 22 Table 3 Summary of Risk Significant CDF Fire Scenarios (CDF Contribution > 1.0%)
(LAR Table W-1 Replacement)
Scenario Description Contribution(1)
Risk Insights FIF(1)
CCDP(1)
(/yr)(1) 10F F16 1X31 - 1B03 XFMR Fire - Target Damage 1.3%
Fire scenario 10F F16 is a fire at the 1B3 480V Load Center 1X31 transformer which is postulated to damage cables in the 98th percentile heat release rate zone of influence. The scenario results in general transient accident sequences with complete loss of Division 1 equipment coupled with maintenance or random failure of Division 2 equipment.
2.19E-04 8.18E-03 6.08E-07 10F F34 1A3 - 4160V SWGR Fire - No Target Damage - Cub. 303 - 312.
1.1%
Fire scenario 10F F34 is a fire at the 1A3 essential switchgear that does not result in a fire induced LOOP. Fire induced damage results in the loss of the switchgear and Division 1 equipment. The scenario results in general transient accident sequences with complete loss of Division 1 equipment coupled with maintenance or random failure of Division 2 equipment.
7.12E-04 8.89E-04 5.44E-07 Notes to Table 3
- 1.
Results based on the FRANC model using NUREG/CR-6850 FIFs at a CCDP truncation of 1E-9. The table only presents the FIF, CCDP, and CDF. Refer to Table D-1 of report 0493080001.006, Rev. 2, for the applicable non suppression probability (NSP) and severity factor (SF).
Page 14 of 22 Table 4 Summary of Risk Significant LERF Fire Scenarios (LERF Contribution > 1.0%)
(LAR Table W-2 Replacement)
Scenario Description Contribution (1)
Risk Insights FIF(1)
CLERP(1)
LERF (/yr)
(1) 10E F01 1D44 - BC Fire - Target Damage -
Full ZOI 13.6%
Fire scenario 10E F01 is a fire at the 1D44 battery charger which is postulated to damage cables in the 98th percentile heat release rate zone of influence. The scenario results in a loss of offsite power given damage to the 1X3 and 1X4 protective relaying cables. 1A3 Essential switchgear is unavailable due to the loss of offsite power coupled with maintenance or random failures of the Standby Diesel Generator 1G31. Offsite power recovery is not credited given the fire damage. Additionally, HPCI and RCIC are unavailable given fire damage to cables. Alternate depressurization methods are not credited post core damage resulting in a failure to arrest the core melt in vessel and subsequent large early release.
1.90E-04 6.87E-02 2.22E-06 10F F14 1B3 - 480V LC Fire - Target Damage 11.3%
Fire scenario 10F F14 is a fire at the 1B3 480V Load Center which is postulated to damage cables in the 98th percentile heat release rate zone of influence. The scenario results in general transient accident sequences with complete loss of Division 1 equipment coupled with maintenance or random failure of Division 2 equipment. Post core damage, core melt is not arrested in vessel, combustible gas venting fails, drywell shell fails, and the Reactor Building in ineffective resulting in a large early release.
2.14E-04 2.55E-02 1.85E-06
Page 15 of 22 Table 4 Summary of Risk Significant LERF Fire Scenarios (LERF Contribution > 1.0%)
(LAR Table W-2 Replacement)
Scenario Description Contribution (1)
Risk Insights FIF(1)
CLERP(1)
LERF (/yr)
(1) 10F F12 1A3 Cub. 312 - 4160V SWGR Fire -
Target Damage 4.3%
Fire scenario 10F F12 is a panel fire at the 1A3 essential switchgear cubicle 312 that is postulated to damage the adjacent cubicles and the cables in the 98th percentile heat release rate zone of influence. The scenario results in a loss of offsite power given damage to the 1X3 and 1X4 protective relaying cables. 1A4 Essential switchgear is unavailable due to the loss of offsite power coupled with maintenance or random failures of the Standby Diesel Generator 1G21. Offsite power recovery is not credited given the fire damage. Additionally, HPCI and RCIC are unavailable given fire damage to cables. Alternate depressurization methods are not credited post core damage resulting in a failure to arrest the core melt in vessel and subsequent large early release.
7.09E-05 7.02E-02 6.97E-07 10E F51 1A4 Cub. 401 - 4KV MVSG Fire -
Target Damage 4.1%
Fire scenario 10E F51 is a panel fire at the 1A4 essential switchgear cubicle 401 that is postulated to damage the adjacent cubicles and the cables in the 98th percentile heat release rate zone of influence. The scenario results in a loss of offsite power given damage to the 1X3 and 1X4 protective relaying cables. 1A3 Essential switchgear is unavailable due to the loss of offsite power coupled with maintenance or random failures of the Standby Diesel Generator 1G31. Offsite power recovery is not credited given the fire damage. Alternate depressurization methods are not credited post core damage resulting in a failure to arrest the core melt in vessel and subsequent large early release.
7.09E-05 6.69E-02 6.64E-07 10E F77 1A4 Cub. 402 - 4KV MVSG Fire -
Target Damage 4.1%
Fire scenario 10E F77 is a panel fire at the 1A4 essential switchgear cubicle 402 that is postulated to damage the adjacent cubicles and the cable tray above. The scenario impacts are similar to scenario 10E F51 7.09E-05 6.69E-02 6.64E-07
Page 16 of 22 Table 4 Summary of Risk Significant LERF Fire Scenarios (LERF Contribution > 1.0%)
(LAR Table W-2 Replacement)
Scenario Description Contribution (1)
Risk Insights FIF(1)
CLERP(1)
LERF (/yr)
(1) 10E F46 1B4 - 480V LC Fire - Target Damage 3.3%
Fire scenario 10E F46 is a panel fire at the 1B4 480V load center that damages the cables in the 98th percentile heat release rate zone of influence. The scenario results in general transient accident sequences with complete loss of Division 2 equipment coupled with maintenance or random failure of Division 1 equipment. Post core damage, core melt is not arrested in vessel, combustible gas venting fails, drywell shell fails, and the Reactor Building in ineffective resulting in a large early release.
2.14E-04 7.45E-03 5.41E-07 10E F05 1XL80 - XFMR Fire - Target Damage 2.4%
Fire scenario 10E F05 is a fire at the 1XL80 transformer that damages the cables in the 98th percentile heat release rate zone of influence. The scenario results in general transient accident sequences with complete loss of Division 2 equipment coupled with maintenance or random failure of Division 1 equipment. Post core damage, core melt is not arrested in vessel, combustible gas venting fails, drywell shell fails, and the Reactor Building in ineffective resulting in a large early release.
2.19E-04 3.78E-03 3.88E-07 11A LERF CSR - LERF 2.3%
Fire scenario 11A LERF is a surrogate for the postulated fire scenarios in the Cable Spreading Room. Refer to report 0493080001.007 for details of the postulated fire scenarios.
The FIF presented in this table is a surrogate for the estimated Cable Spreading Room LERF.
3.69E-07 1.00E+00 3.69E-07 10F F19 1D43 - BC Fire - Target Damage 2.2%
Fire scenario 10F F19 is a fire at the 1D43 Battery Charger that damages the cables in the 98th percentile heat release rate zone of influence. The scenario results in general transient accident sequences with complete loss of Division 1 equipment coupled with maintenance or random failure of Division 2 equipment. Post core damage, core melt is not arrested in vessel, combustible gas venting fails, drywell shell fails, and the Reactor Building in ineffective resulting in a large early release.
1.90E-04 4.02E-03 3.59E-07
Page 17 of 22 Table 4 Summary of Risk Significant LERF Fire Scenarios (LERF Contribution > 1.0%)
(LAR Table W-2 Replacement)
Scenario Description Contribution (1)
Risk Insights FIF(1)
CLERP(1)
LERF (/yr)
(1) 10E F75 1A4 Cub. 405-412-4KV MVSG Fire
- Target Damage 2.1%
Fire scenario 10E F75 is a panel fire at the 1A4 cubicles 405-412 that damages the cables in the 98th percentile heat release rate zone of influence. The scenario results in general transient accident sequences with complete loss of Division 2 equipment coupled with maintenance or random failure of Division 1 equipment. Post core damage, core melt is not arrested in vessel, combustible gas venting fails, drywell shell fails, and the Reactor Building in ineffective resulting in a large early release.
5.70E-04 4.40E-03 3.51E-07 10E F45 1X41 - XFMR Fire - Target Damage 1.9%
Fire scenario 10E F45 is a transformer fire at the 1B4 480V load center 1X41 transformer that damages the cables in the 98th percentile heat release rate zone of influence. The scenario results in general transient accident sequences with complete loss of Division 2 equipment coupled with maintenance or random failure of Division 1 equipment.
Post core damage, core melt is not arrested in vessel, combustible gas venting fails, drywell shell fails, and the Reactor Building in ineffective resulting in a large early release.
8.75E-04 6.03E-03 3.16E-07 10F F16 1X31 - 1B03 XFMR Fire - Target Damage 1.8%
Fire scenario 10F F16 is a fire at the 1B3 480V Load Center 1X31 transformer which is postulated to damage cables in the 98th percentile heat release rate zone of influence. The scenario results in general transient accident sequences with complete loss of Division 1 equipment coupled with maintenance or random failure of Division 2 equipment.
Post core damage, core melt is not arrested in vessel, combustible gas venting fails, drywell shell fails, and the Reactor Building in ineffective resulting in a large early release.
2.19E-04 4.06E-03 3.02E-07 10E F03 1D22 - BC Fire - Target Damage 1.4%
Fire scenario 10E F03 is a 1D22 battery charger fire that results in fire damage to targets in the 98th percentile heat release rate zone of influence. The scenario results in transient sequences without high pressure injection. HPCI and RCIC are assumed failed due to DC power supply failures. Core damage at high pressure without injection results in drywell shell failure.
1.90E-04 4.12E-03 2.35E-07
Page 18 of 22 Table 4 Summary of Risk Significant LERF Fire Scenarios (LERF Contribution > 1.0%)
(LAR Table W-2 Replacement)
Scenario Description Contribution (1)
Risk Insights FIF(1)
CLERP(1)
LERF (/yr)
(1) 10F F11 1A3 Cub. 311 - 4160V SWGR Fire -
Target Damage - Full ZOI 1.3%
Fire scenario 10F F11 is a panel fire at the 1A3 essential switchgear cubicle 311 that is postulated to damage the adjacent cubicles and both cable trays above. The scenario impacts are similar to scenario 10F F12 7.09E-05 6.15E-02 2.18E-07 10F F10 1A3 Cub. 310 - 4160V SWGR Fire -
Target Damage - Full ZOI 1.3%
Fire scenario 10F F10 is a panel fire at the 1A3 essential switchgear cubicle 310 that is postulated to damage the adjacent cubicles and both cable trays above. The scenario impacts are similar to scenario 10F F12.
7.09E-05 6.07E-02 2.15E-07 10F F21 1D12 - BC Fire - Target Damage 1.3%
Fire scenario 10F F21 is a fire at the 1D12 Battery Charger which is postulated to damage cables in the 98th percentile heat release rate zone of influence. The scenario results in transient sequences without high pressure injection. HPCI and RCIC are assumed failed due to the postulated cable damage. Core damage at high pressure without injection results in drywell shell failure.
1.90E-04 4.02E-03 2.14E-07 07A08A A MCA scenario from PAU 07A to PAU 08A 1.3%
Fire scenario 07A08A A is a postulated feedwater pump oil fire that result in assumed wide spread damage to PAU 07A and PAU 08A. The scenario results in transient sequences at low pressure. The Startup Transformer and diesel generators are unavailable due to fire damage. Random failures associated with the Standby transformers result in the loss of low pressure injection. Core damage at low pressure without injection results in early drywell shell failure.
2.65E-04 1.57E-02 2.08E-07 10F F22 1D120 - BC Fire - Target Damage 1.3%
Fire scenario 10F F22 is a fire at the 1D120 Battery Charger which is postulated to damage cables in the 98th percentile heat release rate zone of influence. The scenario results in transient sequences without high pressure injection. HPCI and RCIC are assumed failed due to the postulated cable damage. Core damage at high pressure without injection results in early drywell shell failure.
1.90E-04 3.89E-03 2.07E-07
Page 19 of 22 Table 4 Summary of Risk Significant LERF Fire Scenarios (LERF Contribution > 1.0%)
(LAR Table W-2 Replacement)
Scenario Description Contribution (1)
Risk Insights FIF(1)
CLERP(1)
LERF (/yr)
(1) 10F F38 1A3 - 4160V SWGR Fire - No Target Damage - Cub. 302 1.2%
Fire scenario 10F F38 is a fire in the 1A3 essential switchgear cubicle 302. The fire results in a loss of the switchgear, Startup Transformer, and Division 1 equipment.
The scenario results in a loss of torus cooling due to random failures in Division 2 equipment. Containment is successfully vented; however injection post containment venting is not successful.
7.12E-05 3.34E-03 2.04E-07 10F F36 1B32 - 480V MCC Fire 1.2%
Fire scenario 10F F36 is a fire at the 1B32 MCC that results in fire damage to the MCC and loss of Division 1 equipment.
The scenario results in transient sequences without high pressure injection. HPCI and RCIC are assumed failed due to DC power supply failures. Core damage at high pressure without injection results in early drywell shell failure.
5.70E-04 3.58E-04 2.04E-07 10E F52 1B42 480V MCC Fire 1.2%
Fire scenario 10E F52 is a 1B42 MCC fire that results in fire damage to the MCC and loss of Division 2 equipment. The scenario results in transient sequences without high pressure injection. HPCI and RCIC are assumed failed due to DC power supply failures. Core damage at high pressure without injection results in early drywell shell failure.
4.98E-04 3.88E-04 1.93E-07 10E F50 Bus Duct HEAF 1.2%
Fire scenario 10E F50 is a bus duct HEAF that results in fire damage to targets in the zone of influence. The scenario results in transient sequences without high pressure injection. HPCI and RCIC are assumed failed due to DC power supply failures. Core damage at high pressure without injection results in early drywell shell failure.
5.24E-05 3.62E-03 1.90E-07 10D A01 Bounding Fire 1.1%
Fire scenario 10D A01 is a fire in the 1D1 battery room.
The fire scenario results in loss of high pressure injection sequences. HPCI and RCIC are assumed lost due to DC power failure. Core damage at high pressure without injection results in early drywell shell failure.
5.02E-04 3.47E-04 1.74E-07 10F F47 1D120 - BC Fire - No Target Damage 1.1%
Fire scenario 10F F47 is a fire at the 1D120 battery charger.
The scenario results in loss of high pressure injection sequences. Random failures in DC power supplies results in assumed loss of HPCI and RCIC for high pressure injection. Core damage at high pressure without injection results in early drywell shell failure.
1.90E-04 1.10E-03 1.74E-07
Page 20 of 22 Table 4 Summary of Risk Significant LERF Fire Scenarios (LERF Contribution > 1.0%)
(LAR Table W-2 Replacement)
Scenario Description Contribution (1)
Risk Insights FIF(1)
CLERP(1)
LERF (/yr)
(1) 10F F34 1A3 - 4160V SWGR Fire - No Target Damage - Cub. 303 - 312.
1.0%
Fire scenario 10F F34 is a fire in the 1A3 essential switchgear cubicles. The fire results in a loss of the switchgear and Division 1 equipment. The scenario results in a loss of low pressure injection sequences due to random failures of Division 2 equipment. Core damage at low pressure without injection results in early drywell shell failure.
7.12E-04 2.79E-04 1.71E-07 Notes to Table 4
- 1.
Results based on the FRANC model using NUREG/CR-6850 FIFs at a CLERP truncation of 1E-9. Refer to Table E-1 of report 0493080001.006, Rev. 2, for the applicable non suppression probability (NSP) and severity factor (SF).
Page 21 of 22 Table 5 Duane Arnold Energy Center / Fire Area Risk Summary (LAR Table W-3 Replacement)
Fire Area Area Description NFPA 805 Basis Fire Area CDF/LERF
(/yr)(1)
VFDR (Yes/No)
RAs Fire Risk Eval CDF/LERF
(/yr)(1)
Additional Risk of RAs (/yr)(1)
BA Buffer Area 4.2.3 2.24E-07/4.12E-08 No No N/A N/A CB1 Control Building - Cable Spreading Room, Control Room, and Control Building HVAC Room 4.2.4.2 7.19E-06/7.70E-07 Yes Yes 3.55E-08/3.53E-08 3.55E-08/3.53E-08 CB2 Control Building - Div. 2 Essential Switchgear Room and 1D2 Battery Room 4.2.4.2 1.51E-05/7.48E-06 Yes No N/A CB3 Control Building - Div. 1 Essential Switchgear Room and 1D1 Battery Room 4.2.4.2 2.20E-05/6.50E-06 Yes No 1.82E-08/1.67E-08 N/A CB4 Control Building - Battery Room Corridor and 250 VDC Battery Room 4.2.4.2 8.74E-08/1.65E-08 Yes No 1.72E-10/2.59E-12 N/A DRY Drywell Containment 4.2.3.4 N/A No No N/A N/A EX1 Exterior Plant Areas 4.2.3.2 1.85E-07/1.18E-07 No No N/A N/A IS1 Intake Structure - Div. 1 Pump Area 4.2.3.2 3.82E-08/7.66E-09 No No N/A N/A IS2 Intake Structure - Div. 2 Pump Area 4.2.3.2 7.92E-08/1.70E-08 No No N/A N/A PH1 Pump House - Div. 2 Pump Area 4.2.3.3(b) 4.11E-08/8.09E-09 No No N/A N/A PH2 Pump House - Div. 1 Pump Area 4.2.3.2 1.28E-07/2.71E-08 No No N/A N/A RB1 Reactor Building - Northwest, Southeast, Southwest Corner Rooms and 757 Elevation 4.2.4.2 5.12E-07/2.69E-07 Yes No 7.44E-09/1.07E-09 N/A RB3 Reactor Building - 786 Elevation and above 4.2.4.2 4.03E-07/2.34E-07 Yes No 6.41E-08/2.83E-08 N/A RB4 Reactor Building - Northeast Corner Room 4.2.3.2 5.20E-09/8.49E-10 No No N/A N/A TB1 Turbine Building 4.2.4.2 2.62E-06/8.58E-07 Yes No 1.83E-10/4.91E-11 N/A Total 4.86E-05/1.64E-05 1.26E-07/8.14E-08 3.55E-08/3.53E-08 Notes to Table 5
- 1.
Results based on the FRANC model using NUREG/CR-6850 FIFs at a CCDP/CLERP truncation of 1E-9.
- 2.
CB2 has a VFDR; however, there is not a calculated delta CDF/LERF. Refer to Report Number 0027-0042-000-004 Duane Arnold Energy Center Fire Risk Evaluation for details.
Page 22 of 22 Table 6 Summary of Risk Decrease Associated with Modifications (LAR Table W-4 Replacement)
Fire Area Area Description Fire Area CDF/LERF
(/yr)(1)
Modification (Yes/No)
Fire Area CDF/LERF Without Modification (/yr)(1)
Risk Decrease Associated with Modification (/yr)(1)
BA Buffer Area 2.24E-07/4.12E-08 No 2.24E-07/4.12E-08 N/A CB1 Control Building - Cable Spreading Room, Control Room, and Control Building HVAC Room 7.19E-06/7.70E-07 No 7.19E-06/7.70E-07 N/A CB2 Control Building - Div. 2 Essential Switchgear Room and 1D2 Battery Room 1.51E-05/7.48E-06 No 1.51E-05/7.48E-06 N/A CB3 Control Building - Div. 1 Essential Switchgear Room and 1D1 Battery Room 2.20E-05/6.50E-06 No 2.20E-05/6.50E-06 N/A CB4 Control Building - Battery Room Corridor and 250 VDC Battery Room 8.74E-08/1.65E-08 No 8.74E-08/1.65E-08 N/A DRY Drywell Containment N/A No N/A N/A EX1 Exterior Plant Areas 1.85E-07/1.18E-07 No 1.85E-07/1.18E-07 N/A IS1 Intake Structure - Div. 1 Pump Area 3.82E-08/7.66E-09 No 3.82E-08/7.66E-09 N/A IS2 Intake Structure - Div. 2 Pump Area 7.92E-08/1.70E-08 No 7.92E-08/1.70E-08 N/A PH1 Pump House - Div. 2 Pump Area 4.11E-08/8.09E-09 No 4.11E-08/8.09E-09 N/A PH2 Pump House - Div. 1 Pump Area 1.28E-07/2.71E-08 No 1.28E-07/2.71E-08 N/A RB1 Reactor Building - Northwest, Southeast, Southwest Corner Rooms and 757 Elevation 5.12E-07/2.69E-07 No 5.12E-07/2.69E-07 N/A RB3 Reactor Building - 786 Elevation and above 4.03E-07/2.34E-07 No 4.03E-07/2.34E-07 N/A RB4 Reactor Building - Northeast Corner Room 5.20E-09/8.49E-10 (2)
No 5.20E-09/8.49E-10 (2)
N/A TB1 Turbine Building 2.62E-06/8.58E-07 Yes 5.93E-06/1.52E-06 3.31E-06/6.67E-07 Total 4.86E-05/1.64E-05 5.19E-05/1.70E-05 3.31E-06/6.67E-07 Notes to Table 6
- 1.
Results based on the FRANC model using NUREG/CR-6850 FIFs at a CCDP/CLERP truncation of 1E-9.
- 2.
The ESW B circuit modification for TB1 will also impact RB4. The risk decrease due to the modification is not included in the RB4 fire scenarios resulting in a slight conservatism in the calculated fire risk.
Page 1 of 2 DAEC RAI PRA 83 (Revised)
In a letter dated May 23, 2012, (ADAMS Accession No. ML12146A094) you responded to Probabilistic Risk Assessment RAI 20 and provided the conditional core damage probabilities (CCDP) and the conditional large early release probabilities (CLERP) but did not provide a discussion of the analysis, assumptions, and ignition frequency as requested. The staff is requesting additional information as summarized below:
- a.
Discussion of the analysis, assumptions, and ignition frequency, using the clarification guidance criteria discussed in NEIs letter to NRC dated September 27, 2011 on Recent Fire PRA Methods Review Panel Decision: Clarification for Transient Fires and Alignment Factor for Pump Oil Fires (ADAMS Accession Nos. ML113130448, ML113130451, ML113130453, ML113130454) and as endorsed by the NRC in its letter to NEI dated June 21, 2012 on Recent Fire PRA Methods Review Panel Decisions and EPRI 1022993, Evaluation of Peak Heat Release Rates in Electrical Cabinet Fires (ADAMS Accession No. ML12171A583). Include the basis for the ignition frequency.
Also include justification for the transient heat release rate used.
- b.
If the heat release rate differs from NUREG/CR-6850, EPRI/NRC-RES Fire PRA Methodology for Nuclear Power Facilities, provide a sensitivity study containing the risk and change in risk, using the values in NUREG/CR-6850.
RESPONSE
In response to RAI PRA 14.01 the Cable Spreading Room (CSR) evaluation was updated and is documented in the CSR Fire Scenario and Quantification Report 0493080001.007 Revision 0. Report 0493080001.007 is included on the NextEra Online Reference Portal. Section 4.2.5 of the report discusses the fire scenario postulated that includes Division 1 targets. The scenario designator is DIV1 and the results are presented in Table 5.0-1 and Table 5.0-2.
- a.
Section 4.1 of report 0493080001.007 discusses the assumptions employed in the CSR evaluation. Assumptions include:
Fire ignition sources - Section 4.1.1 Heat release rate, damage threshold, and zone of influence - Section 4.1.2 Detection and Suppression - Section 4.1.3 Fire Propagation - Section 4.1.4 Hot Gas Layer - Section 4.1.5 Section 4.2 of report 0493080001.007 discusses the analysis of the CSR. The CSR was analyzed based on target sets. Section 4.2.5 discusses the postulated fire at the Division 1 penetrations.
Page 2 of 2 Section 3.0 of report 0493080001.007 describes the CSR fire ignition frequencies (FIFs). Section 4.1.1 discusses the fire ignition sources included for the postulated scenarios. The FIF for scenario DIV1 is 2.75E-5/yr and is presented in Table 5.0-1.
The FIF is the sum of the CSR FIFs for NUREG/CR-6850 bins 5, 6, and 7. From Table 3.3-1 the bin 5, 6, and 7 FIFs are 2.93E-5/yr, 2.10E-5/yr, and 7.78E-6/yr, respectively.
As discussed in Section 4.1.3, prompt suppression is included for hotwork fires (i.e., bin 5 and 6) based on FAQ 08-0050 (i.e., 0.392 based on the welding curve). Therefore, the scenario FIF is calculated as follows:
Bin 5 FIF
- NSP = 2.93E-5/yr
- 0.392 = 1.15E-5/yr Bin 6 FIF
- NSP = 2.10E-5/yr
- 0.392 = 8.23E-6/yr Bin 7 FIF = 7.78E-6/yr Total FIF = 1.15E-5/yr + 8.23E-6/yr + 7.78E-6/yr = 2.75E-5/yr.
- b.
As discussed in Section 4.1.2 of report 0493080001.007, the NUREG/CR-6850 transient heat release rate of 317 kW was used.