ML14071A169

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Request for Additional Information
ML14071A169
Person / Time
Site: Summer 
Issue date: 03/24/2014
From: Shawn Williams
Plant Licensing Branch II
To: Gatlin T
South Carolina Electric & Gas Co
Williams S
References
TAC ME7586
Download: ML14071A169 (6)
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Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 March 24, 2014 Mr. Thomas D. Gatlin Vice President, Nuclear Operations South Carolina Electric & Gas Company Virgil C. Summer Nuclear Station Post Office Box 88, Mail Code 800 Jenkinsville, SC 29065

SUBJECT:

VIRGIL C. SUMMER NUCLEAR STATION, UNIT NO.1 (VCSNS)- REQUEST FOR ADDITIONAL INFORMATION (TAC NO. ME7586)

Dear Mr. Gatlin:

By letters dated November 15, 2011, January 26 and October 10, 2012, the South Carolina Electric & Gas Company (SCE&G, the licensee) submitted a license amendment request (LAR) to revise Facility Operating License Number NPF-12 for the Virgil C. Summer Nuclear Station, Unit No. 1. The LAR would permit transition of the fire protection licensing basis from Title 10 of the Code of Federal Regulations (10 CFR), Section 50.48(b), to 10 CFR 50.48(c), "National Fire Protection Association Standard NFPA 805" (NFPA 805).

The staff has determined that additional information is needed to continue the review as discussed in the Enclosure. We request that SCE&G respond to these RAis by May 2, 2014.

Docket No. 50-395

Enclosure:

Request for Additional Information cc w/encl: Distribution via Listserv Sincerely, Shawn Williams, Senior Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation

REQUESTS FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST TO ADOPT PERFORMANCE-BASED NATIONAL FIRE PROTECTION ASSOCIATION STANDARD 805 FOR FIRE PROTECTION FOR VIRGIL C. SUMMER NUCLEAR STATION, UNIT 1 DOCKET NO. 50-395 Probabilistic Risk Assessment (PRA) Request for Additional Information (RAI) 01.02 In a letter dated October 10, 2012Property "Letter" (as page type) with input value "RC-12-0142, License Amendment Request - LAR-06-00055, License Amendment Request to Adopt NFPA 805, Response to Request for Additional Information" contains invalid characters or is incomplete and therefore can cause unexpected results during a query or annotation process. (Agencywide Documents Access and Management System

{ADAMS) Accession No. ML12297A218), the licensee responded to PRA RAI 01 and discussed the treatment of cables fires due to welding and fires of junction boxes. This requires further clarification in order to judge the acceptability of methods employed. See additional requests below:

a. Discuss and justify the acceptability of the approach by which ignition frequencies, which are developed on a compartment-or fire-zone-basis, are apportioned to cables and junction boxes within a transient zone.
b. Discuss how the conditional core damage probability {CCDP) assigned to a junction box was determined and whether it bounds the CCDP associated with all of the cables that enter the junction box. If not bounding, justify the approach. Otherwise, update the PRA and provide the aggregate change in risk evaluation requested in PRA RAJ 98.
c. In a letter dated November 26, 2013Property "Letter" (as page type) with input value "RC-13-0166, License Amendment Request - LAR-06-00055, License Amendment Request to Adopt NFPA 805, Response to Request for Additional Information" contains invalid characters or is incomplete and therefore can cause unexpected results during a query or annotation process. (ADAMS Accession No. ML13333A283), the licensee responded to PRA RAI 93 and stated that for ungrouped transient zones, where separate fire scenarios are postulated, the failure of cables in a single raceway determine the CCDP for the junction box. The staff notes that a single cable tray is not necessarily representative of all the cables entering a junction box and given that the CCOP from a single cable tray is not necessarily higher than the CCDP for all cables entering the junction box, this approach may be non-conservative. Describe whether or not the guidance provided in Frequently Asked Question (FAQ) 13-0006, will be applied.

Note that FAQ 13-0005, "Cable Fires Special Cases: Self-Ignited and Caused by Welding and Cutting" and 13-0006, "Modeling Junction Box Scenarios in a Fire PRA

[FPRA]," offer acceptable resolutions related to cable fires and junction box fires, respectively.

PRA RAI10.03 In a letter dated January 9, 2014 {ADAMS Accession No. ML14013A074), the licensee responded to PRA RAI 10.02 regarding the probability of failing to successfully shutdown the reactor after abandonment of the main control room (MCR) caused by a fire. The licensee provided additional information about the Human Error Probabilities (HEP) estimates in the updated License Amendment Request (LAR), Attachment G. See additional requests below:

a. Summarize the feasibility evaluation for the Control Room Evacuation Fire Response Abnormal Operating Procedure that support the estimates developed, e.g., the time available before core damage and the time required to perform the necessary actions.
b. Clarify how fire affected equipment failure is included in the MCR abandonment scenarios. Include a description of how individual equipment, single spurious, and multiple spurious operational failures are developed for different scenarios.
c. Provide the range of CCDP/ Conditional Large Early Release Probability (CLERP) values used to estimate the MCR abandonment core damage frequency (CDF) and Large Early Release Frequency (LERF) and summarize the types of scenarios that refer to those ranges. Also, indicate what failures (i.e., equipment failures and human action failures) contribute to those values, and how the conditional values are generated from those failures.

PRA RAI10.04 In a letter dated October 10, 2012Property "Letter" (as page type) with input value "RC-12-0142, License Amendment Request - LAR-06-00055, License Amendment Request to Adopt NFPA 805, Response to Request for Additional Information" contains invalid characters or is incomplete and therefore can cause unexpected results during a query or annotation process. (ADAMS Accession No. ML12297A218), the licensee responded to PRA RAI 1 0 and provided discussion on the calculation of the additional risk of recovery actions (RAs) associated with MCR abandonment, indicating that for the compliant plant, RAs are always taken to be successful. For those actions taken in the MCR or at the remote shutdown panel, the HEPs are unchanged between the variant and compliant plant.

For the variant plant, indicate if the equipment credited for control room abandonment for the variant plant is the same as for the compliant plant. If not, evaluate the additional risk of RAs for MCR abandonment relying on the same equipment for the variant and compliant case (e.g., use the variant case PRA model with then without the RAs because NFPA 805 requests the additional risk from RAs after transition).

PRA RAI99 In a letter dated April 1, 2013Property "Letter" (as page type) with input value "RC-13-0054, License Amendment Request - LAR-06-00055 - License Amendment Request to Adopt NFPA 805 Additional Information Regarding Response to Request for Additional Information" contains invalid characters or is incomplete and therefore can cause unexpected results during a query or annotation process. (ADAMS Accession No. ML13092A333), the licensee responded to PRA RAI 07 and addressed the impact of the sensitivity study required as part of FAQ 08-0048, "EPRI/NRC-RES Fire PRA Methodology for Nuclear Power Facilities," (NUREG/CR-6850)

Revised Fire Ignition Frequencies." The licensee noted that the sensitivity study caused the total CDF to slightly exceed one of the Regulatory Guide (RG) 1.17 4, "An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis," acceptance guidelines which would normally mean that any risk increase should be less than 1 E-6/year. Consistent with the guidance in the FAQ, the licensee identified fire protection and related measures that provide additional defense-in-depth as justification for the sensitivity results exceeding the acceptance guideline. Evaluate whether any additional measure would be necessary, if the sensitivity study was applied to the PRA which uses only approved methods (i.e., the PRA requested in PRA RAI 98) and indicate whether any such measures were developed.

PRA RAI 50.01 In a letter dated October 10, 2012Property "Letter" (as page type) with input value "RC-12-0142, License Amendment Request - LAR-06-00055, License Amendment Request to Adopt NFPA 805, Response to Request for Additional Information" contains invalid characters or is incomplete and therefore can cause unexpected results during a query or annotation process. (ADAMS Accession No. ML12297A218), the licensee responded to PRA RAI 50 and indicated that an internal consistency review to the PRA guideline for human reliability would be completed by the end of 2012. Confirm completion of this review.

PRA RAI 66.02 In a letter dated April 1, 2013Property "Letter" (as page type) with input value "RC-13-0054, License Amendment Request - LAR-06-00055 - License Amendment Request to Adopt NFPA 805 Additional Information Regarding Response to Request for Additional Information" contains invalid characters or is incomplete and therefore can cause unexpected results during a query or annotation process. (ADAMS Accession No. ML13092A333), the licensee included an additional response to PRA RAI 66 and indicated that the CDF was unacceptable with the corrections to the model. Describe the additional detailed modeling and increased scope of circuit protection modifications that were implemented and incorporated in the PRA model and indicate if accepted methods were used in these areas.

PRA RAI 86.01 In a letter dated November 26, 2013Property "Letter" (as page type) with input value "RC-13-0166, License Amendment Request - LAR-06-00055, License Amendment Request to Adopt NFPA 805, Response to Request for Additional Information" contains invalid characters or is incomplete and therefore can cause unexpected results during a query or annotation process. (ADAMS Accession No. ML13333A283), the licensee responded to PRA RAI 86 and implied that the total CDF and LERF only reflect internal events and fire risk contributions. The staff notes that the total CDF/LERF must also reflect seismic risk. Provide an estimate of seismic risk, and incorporate the seismic risk in the results of the integrated study RAI 98 to determine if the acceptance guidelines of RG 1.17 4, are met.

PRA RAI98 Section 2.4.3.3 of the NFPA 805 standard incorporated by reference into 50.48(c) states that the probabilistic safety assessment (PSA) (PSA is also referred to as PRA) approach, methods, and data shall be acceptable to the authority having jurisdiction, which is the NRC. RG 1.205, "Risk-Informed, Performance-Based Fire Protection for Existing Light-Water Nuclear Power Plants," identifies NUREG/CR-6850 as documenting a methodology for conducting an FPRA and endorses, with exceptions and clarifications, NEI 04-02, "Guidance for Implementing a Risk-Informed, Performance-Based Fire Protection Program Under [Title 10 of the Code of Federal Regulations] 10 CFR 50.48(c)," Rev. 2, as providing methods acceptable to the staff for adopting a fire protection program consistent with NFPA 805.

The NRC staff identified several methods and weaknesses that were used in the FPRA that have not been accepted by the staff. RAis were provided about these methods and weaknesses and the responses have been reviewed. The staff has concluded that the following methods and weaknesses are unacceptable in that justification does not seem to be complete (e.g., credit for control power transformers is not supported by experiments).

Unacceptable Methods and Weaknesses:

  • PRA RAI 01.01 regarding evaluation of hot work induced cable fires
  • PRA RAI 15.01 on time to damage and crediting suppression across a fire zone boundary
  • PRA RAI 66 on error in calculations of main control board (MCB) fire
  • PRA RAI 73.01 on parameters for cable damage above cabinets with incipient detection installed
  • PRA RAI 83 on assignment of heat release rate (HRR) for the oil spill size
  • PRA RAI 85.01 on propagating parameter uncertainty to obtain a mean value that includes state-of-knowledge correlations.
  • PRA RAI 88 (i.e., SSD RAI 11) on installation of a new power source
  • PRA RAI 93 on evaluating junction boxes
  • PRA RAI 94 on the use of FAQ 12-0064, "Hot Work/Transient Fire Frequency: Influence Factors" to model administrative controls
  • PRA RAI 90 on removal on administrative limit credit The following methods and weaknesses have been identified, but the NRC staff review is continuing with additional RAis and further supporting information has been requested. The NRC staff will review any supporting information received. Alternatively the licensee may replace any of these methods and weaknesses with a method or model previously accepted by the NRC by modifying the FPRA.
  • PRA RAI 95 and 10.02/10.03 on modeling MCR abandonment
  • PRA RAI 01.02 on cable fires from welding and cutting and junction box fires
  • PRA RAI 66.02 on additional detailed modeling and increased scope of circuit protection modifications
a. For each method (i.e., each bullet) above, indicate how the issue (i) is addressed in the final composite analysis results provided in 98.b in support of the LAR and (ii) how the issue will be addressed in the PRA that will be used at the beginning of the self-approval of post-transition changes. In addition, provide confidence (e.g., with a proposed implementation item) that all changes will be made and that a focused-scope peer review will be performed on changes that are PRA upgrades as defined in the PRA standard, and that any findings will be resolved before self-approval of post-transition changes. Note that continued use of unacceptable methods without compensating measures may prevent the staff from completing its review for self-approval.
b. Provide the results of a composite analysis that shows the integrated impact on the transition fire risk (CDF, LERF, delta(~) CDF, ~ L~RF, and the additional risk of recovery actions) after replacing all unacceptable methods and weaknesses with acceptable methods. In the composite analysis, for the cases where individual issues have a synergistic impact on the results, a simultaneous analysis must be performed.

For those cases where no synergy exists, a one-at-a-time analysis may be done. If the impact of an issue on the risk from transition is negligible, as demonstrated by an evaluation in a referenced RAI response or in response to this RAI, it is not necessary to incorporate its effect into the composite analysis. However, all unacceptable methods and weakness should be addressed in the fire FPRA before self-approval evaluations that could be affected by the issue. In the response, explain how the RG

1. 17 4 risk acceptance guidelines are satisfied for the composite analysis and, if applicable, describe any new modifications or operator actions being credited to reduce the delta risk and the associated impacts to the fire protection program.

SSD RAI 21.01 While reviewing the licensee's RAI response letter of February 25, 2014, the staff noted that the RAI package contained a complete revision toLAR Attachment C (NEI 04-02 Table 8-3).

During a cursory review of the revised Attachment C, the staff noted numerous changes that did not appear to be directly related to the changes required to address SSD RAI 21 (elimination of LAR Attachment X). The submittal did not include a list of changes nor an explanation of why the changes were made. Therefore, the NRC staff requests the licensee to provide a list of the changes made to Attachment C and include an explanation for each change.

Some examples identified by the staff to be changes to Attachment C are as follows:

1. For fire area A801, the required fire protection features table does not agree with revised Tables 4-9 and 4-10 from the same RAI response letter.

Fire Zone A801.21.01 requires Suppression & Detection due to FPEEE but 8-3 table does not Fire Zone A801.21.02 requires Suppression due to FPEEE but 8-3 table does not Fire Zone A801.18.01 requires Detection due to FPEEE but 8-3 table does not Fire Zone A801.18.02 requires Detection due to FPEEE but 8-3 table does not

2. DROID A801.10, 13, 14, 15, 16,17-01 appears to delete component IPT00476.
3. Fire Area A801 Fire Risk Summary indicates that this fire area risk dropped almost an order of magnitude when it should have increased a small amount due to several VFDRs addressing 20 foot separation issues.
4. Fire Area C804 appears to delete DROID C804-01.
5. Fire Area C806 appears to delete DROID C806-02.
6. Fire Area C812, DROID C812-18 appears to add a new component failure mode, IFT03531: Available: Non-Spurious.
7. Fire Area C815 appears to delete DROID C815-01.
8. Fire Area C815 appears to add new DROID CB15-67.
9. Fire Area C817 appears to delete DROID C817-01.
10. Fire Area C817 appears to add new DROID C817-68.
11. For Fire Area FH01, the required fire protection features table does not agree with revised Tables 4-10 from the same RAI response letter.

Fire Zone FH01.01 requires Detection due to FPEEE but 8-3 table does not Fire Zone FH01.03 requires Detection due to FPEEE but 8-3 table does not Fire Zone FH01.04 requires Detection due to FPEEE but 8-3 table does not

12. Fire Area 1820, DROID 1820-03 disposition changed from modification to FRE but the Fire Risk Summary numbers went down (previously was 2.61 E-09 CDF, 4.3E-14 LERF both are now E)
13. Fire Area 1825, the required fire protection features table does not agree with revised Tables 4-9 and 4-10 from the same RAI response letter.

Fire Zone 1825.03.01 requires Suppression due to separation and Detection due to FPEEE but 8-3 table does not Fire Zone 1825.03.02 requires Suppression due to separation but 8-3 table does not

14. Fire Area 1825 appears to delete FPEEE 1825-04.
15. Fire Area 1825 appears to add new DROID 1825.08-03.
16. Fire Area 1825 appears to add new DROIDs 1825.01.01,.02,.05-22 and 1825.01.01,.02,

.05-23.

17. Fire Area 1825 appears to delete DROID 1825.03-03.
18. Fire Area R801, DROID R801.02-08 disposition changed from ERF8S modification to FRE.
19. Fire Area SWPH05, removed all requirements for Suppression and Detection.
20. Fire Area T801, added requirement for Suppression in Fire Zone T801.02
21. Fire Area YD02, appears to delete requirements for both Suppression and Detection.

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