ML080940639
| ML080940639 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 04/10/2008 |
| From: | Olshan L NRC/NRR/ADRO/DORL/LPLII-2 |
| To: | Brandi Hamilton Duke Energy Carolinas |
| Olshan L N, NRR/DORL, 415-1419 | |
| Shared Package | |
| ML080980548 | List: |
| References | |
| TAC MC5630 | |
| Download: ML080940639 (144) | |
Text
April 10, 2008 Mr. Bruce H. Hamilton Vice President, Oconee Site Duke Energy Carolinas, LLC 7800 Rochester Highway Seneca, SC 29672
SUBJECT:
OCONEE NUCLEAR STATION, UNIT 3 - PRELIMINARY RESULTS OF THE NRC STAFF REVIEW OF THE FIRE PROBABILISTIC RISK ASSESSMENT MODEL TO SUPPORT IMPLEMENTATION OF NATIONAL FIRE PROTECTION ASSOCIATION STANDARD NFPA-805, PERFORMANCE-BASED STANDARD FOR FIRE PROTECTION FOR LIGHT WATER REACTOR ELECTRIC GENERATING PLANTS (TAC NO. MC5630)
Dear Mr. Hamilton:
This letter is to provide you with a high-level summary and preliminary detailed observations resulting from the U.S. Nuclear Regulatory Commissions (NRCs) review of the Oconee Nuclear Station, Unit 3 (Oconee) fire probabilistic risk assessment (PRA) model. The high-level summary and preliminary detailed observations are provided in the enclosure. A final detailed report is in preparation and will be available in the near future in the Agencywide Documents Access and Management System (ADAMS) at Accession No. ML080940603.
The NRC conducted this review because Oconee is a National Fire Protection Association (NFPA) standard NFPA-805 pilot plant application, and the results of this pre-application audit will support our review of your anticipated license amendment request to transition the Oconee fire protection program to one based on NFPA-805. Licensees that intend to transition to NFPA-805, other than the pilot plants, should plan to subject their fire PRA to an industry peer review as described in Regulatory Guide 1.205, Risk-Informed, Performance-Based Fire Protection for Existing Light-Water Nuclear Power Plants.
NRC staff and contractors conducted a review of the Oconee fire PRA model in the first quarter of calendar year 2008. The onsite portion of the review took place the week of March 17, 2008, at the Oconee site. As stated in an NRC February 20, 2008, letter (ADAMS Accession No. ML080450471), the purpose of the review was to allow the NRC staff to assess the technical adequacy of the base Oconee fire PRA model. Although not a peer review, the NRC staff review was conducted in accordance with the peer review guidelines in the PRA Standard to the extent practicable.
The American Society of Mechanical Engineers (ASME) and American Nuclear Society (ANS) combined PRA Standard, ASME/ANS RA-S-2008, Standard for Level 1/Large Early Release Frequency Probabilistic Risk Assessment for Nuclear Power Plant Application, (draft) hereafter referred to as the PRA Standard, includes a number of technical requirements for assessing the technical adequacy of a fire PRA. A peer review of a fire PRA model, as defined in the PRA Standard, evaluates that model against the applicable requirements. The scope of the review also includes the results of the peer review of the internal events PRA that formed the basis for
B. Hamilton building the fire PRA, as well as the requirements for configuration control and updates to the fire PRA model.
The NRC review team noted that the Oconee Unit 3 fire PRA is not yet complete, although all tasks but one have been started and many of the tasks have been completed. The areas requiring the most additional work include resolution of internal events PRA peer review comments, fire modeling (especially multi-compartment analysis), identification and refinement of higher risk scenarios, and completion of an uncertainty analysis. The NRC team noted that work continues to be done by your staff to finalize the fire PRA.
For the above reasons, the NRC staff review of the Oconee Unit 3 baseline fire PRA cannot be regarded as sufficient for determination of technical adequacy to support risk-informed applications in general. A focused review of those portions of your fire PRA that change substantially in the time between the NRC staff review and your NFPA-805 submittal may be necessary.
If you have any questions regarding this matter, please contact me at (301) 415-1419.
Sincerely,
/RA/
Leonard N. Olshan, Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-287
Enclosure:
As stated cc w/encl: See next page
(Letter) ML080940639 (Pkg) ML080980548 Fire: ML080940603 OFFICE NRR/LPL2-1/PM NRR/LPL2-1/BC NRR/DRA NAME LOlshan MWong SLaur DATE 04/05/08 04/10/08 04/08/08 OFFICE NRR/DRA/AFPB NRR/AFPB NRR/DRA/DD NAME PLain AKleinn MCunningham DATE 04/08/08 04/08/08 04/09/08 Oconee Nuclear Station, Unit 3 cc:
Mr. Bruce H. Hamilton Mr. Leonard G. Green Vice President, Oconee Site Assistant Attorney General Duke Energy Carolinas, LLC NC Department of Justice 7800 Rochester Highway P.O. Box 629 Seneca, SC 29672 Raleigh, NC 27602 Ms. Lisa F. Vaughn Mr. R. L. Gill, Jr.
Associate General Counsel and Managing Manager - Nuclear Regulatory Attorney Issues and Industry Affairs Duke Energy Carolinas, LLC Duke Energy Carolinas, LLC 526 South Church Street - EC07H 526 S. Church St.
Charlotte, North Carolina 28202 Mail Stop EC05P Charlotte, NC 28202 Manager, LIS NUS Corporation Division of Radiation Protection 2650 McCormick Dr., 3rd Floor NC Dept of Environment, Health, & Natural Clearwater, FL 34619-1035 Resources 3825 Barrett Dr.
Senior Resident Inspector Raleigh, NC 27609-7721 U.S. Nuclear Regulatory Commission 7812B Rochester Highway Mr. Peter R. Harden, IV Seneca, SC 29672 VP-Customer Relations and Sales Westinghouse Electric Company Mr. Henry Porter, Director 6000 Fairview Road Division of Radioactive Waste Management 12th Floor Bureau of Land and Waste Management Charlotte, NC 28210 Dept. of Health and Env. Control 2600 Bull St. Mr. Dhiaa M. Jamil Columbia, SC 29201-1708 Group Executive and Chief Nuclear Officer Duke Energy Carolinas, LLC Mr. Michael A. Schoppman P.O. Box 1006-EC03XM Framatome ANP Charlotte, NC 28201-1006 1911 North Ft. Myer Dr.
Suite 705 Mr. Charles Brinkman Rosslyn, VA 22209 Director, Washington Operations Westinghouse Electric Company Mr. B. G. Davenport 12300 Twinbrook Parkway, Suite 330 Regulatory Compliance Manager Rockville, MD 20852 Oconee Nuclear Site Duke Energy Carolinas, LLC Ms. Kathryn B. Nolan ON03RC Senior Counsel 7800 Rochester Highway Duke Energy Carolinas, LLC Seneca, SC 29672 526 South Church Street - EC07H Charlotte, NC 28202
OCONEE NUCLEAR STATION, UNIT 3 PRELIMINARY RESULTS OF THE NRC STAFF REVIEW OF THE FIRE PROBABILISTIC RISK ASSESSMENT MODEL TO SUPPORT IMPLEMENTATION OF NATIONAL FIRE PROTECTION ASSOCIATION (NFPA) STANDARD NFPA-805, PERFORMANCE-BASED STANDARD FOR FIRE PROTECTION FOR LIGHT WATER REACTOR ELECTRIC GENERATING PLANTS, AS ALLOWED UNDER TITLE 10 OF THE CODE OF FEDERAL REGULATIONS, PARAGRAPH 50.48(c)
DOCKET NO. 50-287 I. BACKGROUND Nuclear Regulatory Commission (NRC) staff and contractors conducted a review of the Oconee Nuclear Station, Unit 3 (Oconee) Fire Probabilistic Risk Assessment (fire PRA; FPRA) model in the first quarter of calendar year 2008. The onsite portion of the review took place the week of March 17, 2008, at the Oconee site in Santee, South Carolina. The purpose, methodology, and other aspects of the review may be found in the NRC letter to Duke Power Company (now Duke Energy Carolinas, LLC) dated February 20, 2008 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML080450471).
As stated in that letter, the purpose of the review was to allow the NRC staff to assess the technical adequacy of the base Oconee fire PRA model. The results of this review will support the staffs review of Oconees license amendment request to transition the Oconee fire protection program to one based on the National Fire Protection Association (NFPA) standard NFPA-805, as allowed under Title 10 of the Code of Federal Regulations, Part 50, Section 48(c). The NRC conducted this review because Oconee is a NFPA-805 pilot application.
The American Society of Mechanical Engineers (ASME) and American Nuclear Society (ANS) combined PRA Standard, ASME/ANS RA-S-2008, Standard for Level 1/Large Early Release Frequency Probabilistic Risk Assessment for Nuclear Power Plant Application, (draft), hereafter referred to as the PRA Standard, includes a number of technical requirements for assessing the technical adequacy of a fire PRA. There are thirteen technical elements, each addressing an area or task involved in constructing and using a fire PRA. The technical elements are composed of one or more high level requirements (HLRs). The HLRs are further broken down into one or more supporting requirements (SRs). A peer review of a fire PRA model, as defined in the PRA Standard, evaluates that model against the applicable SRs and the HLRs. In addition to the thirteen elements, the peer review process requires the team to review the results of the peer review of the internal events PRA that formed the basis for building the fire PRA. Finally, the PRA Standard includes requirements for configuration control and updates to the fire PRA model, and a peer review includes an assessment of those requirements.
The NRC staff review of the Oconee fire PRA model was a pre-application audit of the technical adequacy of the base fire PRA that will be used to support a license amendment request to transition the plants fire protection program to one based on NFPA-805, as stated above.
Although not a peer review, the NRC staff review was conducted in accordance with the peer review guidelines in the PRA Standard to the extent practicable.
A report is in preparation to document the staffs review of the Oconee Unit 3 FPRA in a manner consistent with the requirements in the PRA Standard. The report will include not only the findings resulting from the NRC staff review of the fire PRA, but also information regarding review team members and qualifications. Paragraph V of the February 20, 2008, letter describes the content of the report that is being prepared.
This document provides the preliminary technical findings from the NRC staff review. It is being made available in advance of the final report so that interested stakeholders and Oconee are afforded a timely accounting of the results of the review. While there may be changes to some of the technical findings between issuance of this report and the final version, these are expected to be minor and should not impact the ability of Oconee to begin addressing the findings or of the public to be informed of their general nature.
II.
SUMMARY
OF FIRE PRA STAFF REVIEW High-Level Results of the NRC Staff Review of the Oconee Fire PRA Model The NRC review team noted that the Oconee Unit 3 fire PRA is not yet complete, although all tasks but one have been started and many of the tasks have been completed. The areas requiring the most additional work include resolution of internal events PRA peer review comments, fire modeling (especially multi-compartment analysis), identification and refinement of higher risk scenarios, and completion of an uncertainty analysis. The NRC team noted that work continues to be done by your staff to finalize the fire PRA.
For the above reasons, the NRC staff review of the Oconee Unit 3 baseline fire PRA cannot be regarded as sufficient for determination of technical adequacy to support risk-informed applications in general. A focused review of those portions of your fire PRA that change substantially in the time between the staff review and your NFPA-805 submittal may be necessary.
Scope of Review There are 187 SRs in the fire portion of the PRA Standard if the model configuration control and update requirements are included. The NRC staff reviewed 172 SRs applicable to the Oconee fire PRA model. An additional two SRs could not be reviewed because Oconee had not yet completed the uncertainty and sensitivity analysis element.
The scope of this review included both estimation of core damage frequency (CDF) and large early release frequency (LERF) resulting from internal fire events.
General Findings and Results There were a number of findings and suggestions1 as a result of the NRC staff review of the Oconee Unit 3 fire PRA model. The detailed facts and observations (F&Os) are in the next section. The findings and suggestions included the following:
- Fire PRA model developed before resolving current PRA model issues o Issues from 2006 Maracor review not resolved o Internal events PRA model upgrade in progress parallel to FPRA development o Un-reviewed and undocumented 2005 fire PRA logic used in current FPRA for a few scenarios o Documentation describing LERF analysis needs improvement
- Issues with fire modeling o Open issue regarding cables with Polyvinyl Chloride (PVC) jackets (horizontal propagation of fires; failure threshold with pooling of PVC at the cables) o Fire brigade response time with respect to hot gas layer formation o Requirements for treatment of multi-compartment fire scenarios not met o Documentation of boundaries; general nature and key or unique features of partitions
- Plant response model and quantification o Choice of initiating event to use for a given fire scenario not documented or justified. Inconsistent treatment (most fire scenarios utilize a selected transient initiator from the internal events PRA model, but a couple cases use fire initiating events from the un-reviewed 2005 fire PRA logic) o Convergence of results for selected truncation limit not demonstrated o Use of nominal human error probabilities (HEPs) during quantification may result in cutset loss due to truncation o Have not identified significant contributors in accordance with definitions in the PRA Standard; inconsistencies between LERF and CDF cutsets not explained o Potential issue regarding breaker coordination analysis
- Human reliability analysis o No documentation for how procedures (alarm response, emergency, abnormal operating, and safe-shutdown facility) are followed given a fire o No documentation on why the Internal Events PRA human failure events (HFEs) are still valid o Basis for HEP adjustment process not documented 1
Findings and Suggestions are discussed in NEI-07-12, Fire Probabilistic Risk Assessment (FPRA) Peer Review Process Guidelines, Draft Version F (ADAMS Accession No. ML073551166)
o HFEs added for the 2005 fire PRA are not developed to the same level of detail as the other HFEs in the model.
o Several issues regarding human reliability analysis (HRA) timing (relative timing of the HFEs in the accident scenarios; adjustment of HEP based on time from cue rather than from fire; dependency based on comparison of cognitive times rather than time separation)
- The seismic fire element is not complete (need to evaluate suppression diversion; fire pre-plan does not cover seismic; seismic plant response procedure does not cover fire)
- One area not performed (uncertainty and sensitivity analysis)
About 43 percent of the HLRs had one or more SR that was not met. While HLRs are not assigned a capability category as are the SRs, all applicable SRs must be met at some level in order to conclude that the HLR has been satisfied. The second table shows that almost 80 percent of the applicable SRs were met.
Two caveats are associated with the SRs that are shown as met. First, in some areas the Oconee Unit 3 fire PRA is still being refined, and an update to the internal events model is in progress. To the extent that changes made to the fire model are substantive, additional or follow-on review of those changes may be warranted (e.g., through a focused peer review of those areas). The second caveat is that the assigned capability categories apply to the base Oconee unit 3 fire PRA model. Oconee will need to determine what capability category is necessary to support a given risk-informed application, such as transition to NFPA-805.
High Level Requirements Overview: # %
HLRs with "Not Met" SRs 22 43.1%
HLRs not Ready for Review 1 2.0%
HLRs with no SRs "Not Met"
- 28 54.9%
Total: 51 100.0%
Supporting Requirements Overview # %
SRs Not Met - Model Appears Ready 33 19.0%
SRs Not Reviewed - Model Not Ready 2 1.1%
SRs Appeared to be Met 139 79.9%
Total: 174 100.0%
III. PRELIMINARY DETAILED FINDINGS OF THE NRC STAFF REVIEW This section presents the detailed findings of the NRC staff review team, organized by PRA Standard technical element. Summary tables showing a breakdown of HLRs, SRs, and numbers of F&Os are presented first. The review of the internal events PRA quality is documented next, followed by the thirteen technical elements in the same order as presented in the PRA Standard, section 3-1.7. The final section contains the results of the assessment of the PRA configuration control/model update area.
A typical section that follows has an up-front introduction, followed by a summary of the review teams conclusions regarding each HLR for that element. A second table2 provides the individual assessment of each SR that supports that HLR. Finally, the fact and observation (F&O) forms associated with that technical element are provided for each finding and suggestion generated by the review team.
As shown in the following table, the NRC review team identified 41 findings and 25 suggestions, for a total of 66 F&Os.
Oconee Unit 3 Fire PRA - Number of F&Os by Element F&O Type Element Finding Suggestion
- Internal Events Peer Review 2 PP Plant Partitioning 3 2 ES Equipment Selection CS Cable Selection and Location 2 QLS Qualitative Screening 1 PRM FPRA Plant Response Model 2 3 FSS Fire Scenario Selection and Analysis 13 9 IGN Ignition Frequency 1 3 QNS Quantitative Screening CF Circuit Failures 3 HRA Human Reliability Analysis 6 2 SF Seismic Fire 3 FQ Fire Risk Quantification 5 UNC Uncertainty and Sensitivity Analysis 1 MUD PRA Configuration Control 2 3 Total: 41 25 2
The internal events PRA review has no HLRs or SRs, so a SR summary table is not included.
The table below shows the number of supporting requirements that were not met in each HLR. An HLR is designated by the element abbreviation followed by a letter; for example, PP-A.
Oconee Unit 3 Fire PRA High Level Requirements Summary Number of Supporting Requirements "Not Met" Element A B C D E F G H
- Internal Events Peer Review -
PP Plant Partitioning 2 1 ES Equipment Selection CS Cable Selection and Location 1 1 QLS Qualitative Screening 1 PRM FPRA Plant Response Model 1 NA 1 FSS Fire Scenario Selection and Analysis 1 1 6 2 IGN Ignition Frequency QNS Quantitative Screening CF Circuit Failures HRA Human Reliability Analysis 1 1 1 SF Seismic Fire 3 FQ Fire Risk Quantification 1 1 1 1 1 UNC Uncertainty and Sensitivity Analysis NR MUD PRA Configuration Control 3 1 Sum: 6 9 5 1 3 1 6 2
The following table shows the number of SRs in each element that met a given capability category. It includes the number of SRs that did not meet any capability category, and includes columns for not reviewed and not applicable. The not reviewed designation is applied to SRs that should have been met but the associated task was not complete as of the onsite review.
Oconee Unit 3 Fire PRA Supporting Requirements Summary Element Not Met Met 1 1&2 2 2&3 3 Not Rev NA
- Internal Events Peer Review PP Plant Partitioning 3 6 1 1 1 ES Equipment Selection 8 1 2 4 CS Cable Selection and Location 2 13 1 QLS Qualitative Screening 1 6 PRM FPRA Plant Response Model 2 18 2 FSS Fire Scenario Selection and 10 20 6 5 4 1 1 3 Analysis IGN Ignition Frequency 10 3 2 QNS Quantitative Screening 5 1 CF Circuit Failures 2 1 HRA Human Reliability Analysis 3 3 2 SF Seismic Fire 3 3 FQ Fire Risk Quantification 5 4 1 UNC Uncertainty and Sensitivity 2 1 Analysis MUD PRA Configuration Control 4 9 1 Totals: 33 107 10 5 6 3 8 2 13
REVIEW INTERNAL EVENTS PRA QUALITY The combined PRA standard states that the review team should verify that the internal events PRA has been reviewed against the internal events elements, high-level requirements and supporting requirements, and that the fire PRA review team should review the outcome of that effort. It further states that results of the internal events PRA review shall be used in support of the determination of the capability category for supporting requirements in the fire PRA standard that reference requirements from the internal events section.
The most recent peer review was performed in 2006 by Maracor on Rev. 3a of the Oconee PRA, developed in March 2005. The peer review identified 159 supporting requirements as partially met at Capability Category II, 103 not met at Capability Category II, 21 met at Capability Category I. There were 23 supporting requirements that were determined to be indeterminate.
Oconee personnel determined that all but 60 of the Maracor issues were not valid findings, but documentation to justify these determinations was not provided. From these Oconee determined that 31 were important to the fire PRA.
Section 1-6.6.2 of the combined PRA standard states: Resolution of Peer Review Team comments shall be documented. Exceptions to the alternatives recommended by the Peer Review team shall be justified. This portion of the standard was not met with respect to the issues identified for the Oconee internal events PRA (F&O finding IEPRA-1)
The NRC staff review team attempted to identify the Maracor issues that potentially affect the linkage between the internal events PRA and the FPRA. Oconee staff was questioned regarding the status of these "issues," and their responses were reviewed. Of the "issues," the one related to "Human Reliability (HR) Post-Initiator Recoveries" requires particular attention with regard to the linkage between the internal events PRA and FPRA. The staff provided other comments as well (see F&O finding IEPRA-2).
Note that the NRC staff did not perform a detailed review of the internal events PRA model or of the specific issues identified by Maracor. The staff identified a subset of the issues that may impact the fire PRA, but the list should not be considered all-inclusive. Resolution of F&O IEPRA-2 should not focus on the comments provided herein; the Oconee staff should disposition all the issues identified in the Maracor peer review. Any interface with resolution of F&O finding PRM-B1-1 should be addressed as well.
SR Level Observation Basis Cap Cat IEPRA Finding Document resolution of the issues identified in F&O IEPRA-1 N/A the Maracor review; justify any exceptions.
IEPRA Finding Need to perform updates credited in "Oconee F&O IEPRA-2 N/A Responses" to the 2006 Maracor review.
See also F&O PRM-B1-1.
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number : IEPRA-1 Level of Significance: Finding Reviewer: SCD Capability Category: N/A OBSERVATION:
The issues identified in the Maracor report documenting the peer review of the Oconee PRA revision 3a (March 2005) have not been resolved. In many cases, the licensee does not agree that the issues are applicable. The resolution has not been documented. Exceptions to the alternatives recommended by the Peer Review have not been justified.
BASIS FOR LEVEL OF SIGNIFICANCE:
Section1-6.6.2 of the combined PRA standard states: Resolution of Peer Review Team comments shall be documented. Exceptions to the alternatives recommended by the Peer Review team shall be justified.
POSSIBLE RESOLUTION (REVIEWER):
Document resolution of the issues identified in the Maracor review; justify any exceptions.
Reference(s): Personnel Contacted:
2006 Maracor Oconee-3a PRA Peer Review
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :IEPRA-2 Level of Significance: Finding Reviewer: RHG Capability Category: Not Met OBSERVATION:
The most recent "peer review" was performed in 2006 by MARACOR on Rev. 3a of the Oconee PRA, developed in March 2005. The following "issues" (the MARACOR review did not specifically characterize these as F&Os, nor did they assign severity levels) were considered by the staff to have the most potential to affect the linkage between the internal events PRA and the FPRA. Oconee staff was questioned regarding the status of these "issues," and their responses are provided below following each issue.
- Grouping: When subsuming an initiator into another, assure that the subsumed initiator frequency is added to that of the subsuming initiator. Also re-examine the assumption that the initiator for loss of power to 4160-VAC bus 3TC bounds all other bus losses of power. The appropriate IE SRs are not identified, nor is the resolution discussed. Oconee Response:
Grouping of initiators (SR IE-B3) in "Response Table [Att. 2]") is addressed in OSC-9068, but an update is needed to add initiators for buses 3TD and 3TE (not necessarily bounded by existing initiator for bus 3TC).
ACCIDENT SEQUENCES (AS)
- Dependencies: Examine the adequacy of DC power and the effect of environmental conditions during SBO/LOOP. The appropriate AS SRs are not identified, nor is the resolution discussed.
Oconee Response: SAAG 519 for LOOP Recovery should be enhanced to discuss DC power adequacy and environmental conditions (SR AS-B6 in "Response Table [Att. 2]").
SYSTEMS (SY)
- CCF/Dependencies: References are needed for plant-specific analyses of HVAC during accident mitigation. The appropriate SY SRs are not identified, nor is the resolution discussed.
Oconee Response: Temperature analyses for SQUG equipment (OSC-6579) did not address HVAC failure dependencies in heatup calculations. These need review to determine if the existing conclusions of no HVAC failure effect on heatup remain valid. Each conclusion will be documented in the system model along with the applicable heatup calculation (SR SY-A17 in "Response Table [Att. 2]"). Also, OSC-9068, Rev. 1, identifies a Loss of HVAC initiator for the electrical equipment rooms and Main Control Room for an extended period of time, due to which spurious instrument behavior could result.
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :IEPRA-2 Level of Significance: Finding Reviewer: RHG Capability Category: Not Met HUMAN RELIABILITY (HR)
- Post-Initiator Recoveries: When recoveries are credited, the following plant-specific justifications must be provided: (1) that the recovery is proceduralized and trained-upon (if not, then justification is needed as to why this should be credited); (2) that appropriate "cues" exist to alert the operator to perform the recovery, with a basis on procedures, training or skill-of-craft; (3) that PSFs are considered; and (4) that there is sufficient manpower to perform the recovery (SR HR-H2). In addition, dependencies among the recoveries themselves and between the recoveries and "non-recovery" human actions must be examined. Oconee Response: Oconee staff recognize that more detailed documentation would be desirable for all of these. Any interface with resolution of the Finding for SR FQ-xx should be addressed as well.
QUANTIFICATION (QU)
- Quantification Methodology: The convergence of CDF truncation values must be demonstrated. The appropriate QU SRs are not identified, nor is the resolution discussed.
Oconee Response: A truncation convergence study, or equivalent, is needed to determne the lowest level of truncation for which adequate convergence is assured. Cognizance must be kept of the systematic underestimation of RAW values due to truncation (SR QU-B2 in "Response Table [Att. 2]"). The truncation issue carries over into the fire PRA; see F&O FQ-B1-1.
LEVEL 2 (LE)
- In general, Oconee PRA Rev. 3a meets CC I for the SRs in this element because it used NUREG/CR-6595 for its Level 2 analysis. A need to review the dominant LERF contributors was cited, and this appears to have been completed through the "Results and Insights from Oconee PRA Rev. 3a" report. Oconee does not discuss any plans to aspire to CC II for the Level 2 analysis. Oconee Response: Although many of the SRs for LE have been determined to meet CC-II ("Response Table [Att. 2]"), a large number of model enhancements are recommended, including plant-specific Level 2 analysis beyond the generic approach of NUREG/CR-6595, consideration of potential SAMG effects, and reintroduction of the analysis for thermally-induced SGTR into the PRA.
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :IEPRA-2 Level of Significance: Finding Reviewer: RHG Capability Category: Not Met MAINTENANCE AND UPDATE (MU)
- Plant Consistency: The M&U procedure needs to be updated to the ASME internal events PRA standard. The appropriate MU SRs are not identified, nor is the resolution discussed.
Oconee Response: "Workplace Procedure for PRA Modeling Guidelines," Rev. 10, (XSAA-115),
has been updated to and also now references ASME RA-Sb-2005.
- Impact of Pending Changes on PRA: Oconee needs to annually assess the cumulative impact of pending changes upon the PRA, as required by its procedures. In addition, any PRA updates must comply with the ASME internal events PRA standard. The appropriate MU SRs are not identified, nor is the resolution discussed. Oconee Response: "Workplace Procedure for Risk Impact Review of Nuclear Plant Changes ..." (XSAA-101) requires an annual trending of the PRA Change Database. This was last performed on 3/12/08 ((NED-A08-7).
BASIS FOR LEVEL OF SIGNIFICANCE:
To meet the requirements of the ASME/ANS standard for the fire PRA, the internal events model used as a basis for building the PRM should meet the requirements of the internal events PRA standard.
POSSIBLE RESOLUTION (REVIEWER):
While the staff identified a subset of the issues it considered most relevant to the fire PRA, resolution of the issues should not focus on this subset. Instead the Oconee staff should disposition all the issues identified in the peer review by either resolving them or explaining why they are not relevant to the fire PRA.
Reference(s): Personnel Contacted:
- 1. 2006 Maracor Oconee-3a PRA Peer Brandi Weaver Review & Oconee Draft Response Table Rob Boyer (as per Rob Boyer, Attachment 2)
- 2. The 60 ASME SRs that are not fully met for Oconee
- 3. Results and Insights from Oconee PRA Revision 3a
- 4. Oconee Rev 3a. F & O Status
- 5. XSAA-115, Rev. 10
- 6. OSC-9068, Rev. 1
- 7. XSAA-101
- 8. NED-A08-7
PLANT PARTITIONING ELEMENT This element defines the physical boundaries of the analysis (i.e., the locations within a plant where fire scenarios are postulated),
and divides the various volumes within that boundary into physical analysis units generally referred to as fire areas or fire compartments. Fire is a highly spatial phenomenon; hence, FPRA quantification and reporting is generally organized in accordance with the physical divisions (the physical analysis units) defined during plant partitioning.
HIGH LEVEL REQUIREMENTS FOR PLANT PARTITIONING (PP)
HLR HLR Description HLR Summary (From Review)
HLR-PP-A The FPRA shall define the global Review of documentation and a plant tour show that the global boundaries do boundaries of the analysis so as to include all plant locations relevant to the plant-wide FPRA.
include all plant locations relevant to the plant-wide FPRA.
HLR-PP-B The FPRA shall perform a Plant HLR-PP-B is not fully met because SRs, PP-B2 and PPB-3 have not been met.
Partitioning analysis to identify and define However, the failure to meet these two SRs does not appear to have had an the physical analysis units to be adverse impact on the analysis quality or completeness. The analysis has applied a considered in the FPRA. fire scenario development methodology that is somewhat different from the FPRA structure embodied in the standard. Fire Compartments are based on Fire Zones rather than Fire Areas. The turbine building Fire Compartments do not all have walls that would contain a fire, but do correspond to areas that a fire could be reasonably be confined to by suppression. PP-B2 and PP-B3 include a requirement to justify that physical analysis unit boundaries are "sufficient to substantially contain the damaging effects of fires" when crediting non-rated walls/floors/ceiling elements or spatial separation as a partitioning element - this was not done.
However, the analysis has, in effect, not exercised the assumption that the partitions will "substantially contain the damaging effects of fires." Instead, in the development of fire scenarios, physical analysis unit boundaries have been ignored in assessing the zone of influence for the fire scenarios. That is, the individual fire scenarios in such physical analysis units inherently capture multi-compartment fire damage. The approach taken is reasonable in view of the large area of the turbine building. The multi-compartment fire modeling needs to be reviewed carefully to insure that it properly handles postulated fires that could spread across some Fire Compartments
HIGH LEVEL REQUIREMENTS FOR PLANT PARTITIONING (PP)
HLR HLR Description HLR Summary (From Review)
HLR-PP-C The FPRA shall document the results of The plant described the global analysis boundary and this boundary includes all the Plant Partitioning analysis in a manner structures and equipment that could reasonably be expected to be included in the that facilitates FPRA applications, analysis.
upgrades, and peer review.
The Equipment Selection Report, OSC-8979, does not adequately describe the general nature and key/unique features of each Fire Compartment. Its usability could be improved by adding details describing the physical boundaries of the Fire Compartments.
SUPPORTING REQUIREMENTS FOR PLANT PARTIONING SR Level Observation Basis Cap Cat PP-A1 Summary Overall Global Analysis boundary seems to Met include all equipment and equipment that could threaten vital equipment if it caught fire. Sister units 1 and 2 equipment - specifically power supplies and control cables - are included in the global analysis boundary as needed.
PP-A1 Reviewed global site drawings outlying buildings in and out of the FPRA. Adequate criteria were used to determine those building in, those out, and those that are exposure hazards. Also reviewed plan view drawings of the turbine, aux, and containment buildings and the selection of fire zones. The sister units were taken into account.
PP-B1 Summary Fire Compartments are based on Fire Zones 2&3 rather than Fire Areas. The turbine building Fire Compartments do not all have walls that would contain a fire, but do correspond to areas that a fire could be reasonably be confined to by suppression.
The approach taken is reasonable in view of the large area of the turbine building. The multi-compartment fire modeling needs to be reviewed carefully to insure that it properly handles postulated fires that could spread across some Fire Compartment boundaries PP-B1 Suggestion The SSF should be divided into more than one F&O PP-B1-1 Fire Compartment; it has a control room and a Diesel room that are separated by fire doors.
The Keowee station dam should be divided into Fire Compartments or justification for not doing so should be provided.
PP-B1 For the purposes of the global plant analysis boundary, the buildings included in the FPRA were divided into a number of fire compartments corresponding to their IPEEE fire zones. The analysis then considers the impact of fires in a given zone, and those fire scenarios that might impact multiple zones. Due to the limited number of physical analysis units (fire areas), this procedure did not follow the standard FPRA methodology. The product of this task imposed an increased burden for the analysis of multi-compartment fire scenarios.
Buildings like the Keowee Station and the Essential Siphon Vacuum building were not
SUPPORTING REQUIREMENTS FOR PLANT PARTIONING SR Level Observation Basis Cap Cat partitioned into separate fire areas and were considered single fire areas in the fire scenario report.
It was noted that the SSF partitioning was not noted in Table 9.1 for plant partitioning, but compartmentalization was credited in the fire scenario report.
PP-B2 Finding The FPRA credited partitioning elements that F&O PP-B2-1 Not Met lacked fire resistance rating.
PP-B3 Finding Some turbine building Fire Compartments have F&O PP-B3-1 Not Met boundaries that do not correspond to a physical wall, and thus have no fire rating. The use of these boundaries implies crediting spatial separation; therefore the standard is not met at Category 1.
PP-B4 Summary Did not credit raceway fire barriers, thermal N/A wraps, fire-retardant coatings, radiant energy shields, or any other localized cable or equipment protection feature as partitioning elements in defining physical analysis units. This was verified by walkdown on 18 March 08.
PP-B5 Summary Did not credit active fire barrier elements as a 1 partitioning feature for the roll-up fire door between Block House 1&2 and CT-4 or fire door closure devices in the SSF. Fire Dampers between Unit 1 and 2 Electrical Equipment rooms and Unit 1 and 2 Cable Spreading rooms were already defined and justified.
PP-B5 Roll-up door in the Blockhouse between CT-4 and BH-12 is a rated door with automatic closing feature. This was verified by walkdown on 18 March 08.
This door is not credited since it is in a wall internal to Fire Compartment including Fire Area CT4 and Fire Area BH12.
Fire Dampers between Unit 1 and Unit 2 Electrical Equipment Rooms are not included in the analysis, but are part of a credited fire barrier, the wall between these 2 Fire Compartments.
(Unit 3 cables run through Unit 1 and Unit 2 Electrical Equipment Rooms)
PP-B6 Summary Oconee lined up their physical analysis units with Met fire zones with in fire areas. No physical analysis units were found to be left out of the global analysis boundary or found to be overlapping.
No two Fire Compartments overlap per drawings O-5 to O-11. The Fire Compartments cover all of
SUPPORTING REQUIREMENTS FOR PLANT PARTIONING SR Level Observation Basis Cap Cat the area contained in the global analysis boundary.
PP-B7 Summary Conducted a walkdown on 18 March 08, covering Met most of the turbine building, the SSF, the Unit 3 Main Control Room, the Unit 3 Equipment Room, auxiliary building, and the transformers and other equipment in the yard. The walkdown did not identify any significant issues with partitioning.
PP-C1 Summary Global Analysis boundary includes the entire Met main plant building, plus parts of the yard equipment. These are documented in a table in OSC-8789.
The most useful documentation of the boundaries is by hand-drawn boundaries on a single set of plant drawings (drawings O-5 to O-11). A more controlled, official version of this documentation should be prepared, preferably in a way that it can be made available on some sort of electronic media. These drawings do not show the Keowee dam and don't show the detail of the SSF, which are needed for a complete analysis.
PP-C2 Summary Reviewed marked-up site drawing and compared Met to selection criteria in OSC-8979 for excluded site areas. Locations excluded from the global analysis boundary are buildings in the yard that do not contain any safety-related equipment and any reasonably postulated fire in them cannot affect safety-related equipment PP-C3 Finding The lack of rated barriers was documented in F&O PP-C3-1 Not Met OSC-8979:
PP-C3 Suggestion OSC-8979 does not adequately describe the F&O PP-C3-2 general nature and key/unique features of each Fire Compartment. Its usability could be improved by adding details describing the physical boundaries of the Fire Compartments.
PP-C4 Summary Compartment naming scheme combines the Met building and IPEEE fire zone designation to facilitate the review. The Fire Compartments are numbered from 01 to (about) 124. The numbering scheme goes across all 3 units, with lower numbers generally corresponding to lower elevations and/or turbine building locations.
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :PP-B1-1 Level of Significance: Suggestion Reviewer: MXM Capability Category: 2&3 OBSERVATION:
The SSF should be divided into more than one Fire Compartment, it has a control room and a Diesel room that are separated by fire doors.
The Keowee station dam should be divided into Fire Compartments as well BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :PP-B2-1 Level of Significance: Finding Reviewer: PWL Capability Category: Not Met OBSERVATION:
The FPRA credited partitioning elements that lacked fire resistance rating. The lack of rated barriers was documented in OSC-8979: fire compartments are generally well defined enclosed volumes that can substantially contain the effects of fire. This description is consistent with the fire areas within the Oconee Appendix R Program. However, Oconee has relatively few enclosed volumes (fire areas) with physical barriers to prevent the spread of fire from one zone to another. For example, a single fire area, BOP, encompasses the Auxiliary Building and Turbine Building for all 3 units with the exception of the West Penetration Rooms. Oconee partitioned the plant into a greater number of compartments based on fire zones rather than fire areas and increased the burden for the analysis of multicompartment fire scenarios.
Credit for fire rated barriers was taken for fire area boundaries, except in BH03, credit was taken for a fire barrier between the Block House and the turbine building without rated penetrations for two fans. {combined from another record - check for duplication: Some turbine building Fire Compartments have boundaries that do not correspond to a physical wall, and thus have no fire rating. The standard is not technically met.
Harold Lefkowitz stated that the Fire Compartments correspond to Fire Zones established about 1995, and that they correspond to areas that a fire can be confined to by suppression and/or Fire Brigade actions. A plant walkdown verified that the turbine building Fire Compartments represent reasonable subdivisions of the turbine building area.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. General Arrangement Plan DWGs 0-5 to Kiang Zee 0-11 Harold Lefkowitz
- 2. OSC-8979
- 3. R0237-05-0001.04
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :PP-B3-1 Level of Significance: Finding Reviewer: PWL Capability Category: Not Met OBSERVATION:
For the purposes of the global plant analysis boundary, the buildings included in the FPRA were divided into a number of fire compartments coresponding to their IPEEE fire zones. The analysis then considers the impact of fires in a given zone, and those fire scenarios that might impact multiple zones. Due to the limited number of physical analysis units (fire areas), this procedure did not follow the standard FPRA methodology. This resulted in additional work for the multiple compartment modeling. {added from another record; check for redundancy: Some turbine building Fire Compartments have boundaries that do not correspond to a physical wall, and thus have no fire rating. The use of these boundaries implies crediting spatial separation, therefore the standard is not met at Category 1.
Harold Lefkowitz stated that these correspond to established Fire Zones established about 1995, and that they correspond to areas that a fire can be confined to by suppression and/or Fire Brigade actions. Due to the unique large turbine building at Oconee, most turbine building Fire Compartments are administrative rather than physical boundaries, interaction between them should be treated in the Multi-Compartment Analysis.}
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. OSC-8979 Drawings O-5 to O-11 Harold Lefkowitz
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :PP-C3-1 Level of Significance: Finding Reviewer: PWL Capability Category: Not Met OBSERVATION:
The lack of rated barriers was documented in OSC-8979: Fire compartments are generally well defined enclosed volumes that can substantially contain the effects of fire. This description is consistent with the fire areas within the Oconee Appendix R Program. However, Oconee has relatively few enclosed volumes (fire areas) with physical barriers to prevent the spread of fire from one zone to another. For example, a single fire area, BOP, encompasses the Auxiliary Building and Turbine Building for all 3 units with the exception of the West Penetration Rooms.
The fire compartments analyzed in FRANC are consistent with Oconees fire zones rather than its designated fire areas. Oconee partitioned the plant into a greater number of compartments based on fire zones rather than fire areas and increased the burden for the analysis of multicompartment fire scenarios.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. OSC-8979
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/17/2008 ID Number :PP-C3-2 Level of Significance: Suggestion Reviewer: MXM Capability Category:
OBSERVATION:
OSC-8979 does not adequately describe the general nature and key/unique features of each Fire Compartment. It's usability could be improved by adding details describing the physical boundaries of the Fire Compartments.
The Fire Compartments are either the same as, or are groups of, the Fire Zones established about 1995. In the basement, and in the Auxiliary Building, the Fire Zones generally correspond with actual rooms. The 3 reactor buildings are one Fire Compartment each. Due to the unique large turbine building at Oconee, most turbine building Fire Compartments are administrative rather than physical boundaries, interaction between them should be treated in the Multi-Compartment Analysis.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
EQUIPMENT SELECTION ELEMENT This element identifies (and locates) the set of plant equipment that will be included in the FPRA. This includes: a) equipment that, if damaged as a result of a fire will lead to a plant trip (or other initiating event) either directly or as a result of operator action in response to a fire, b) equipment required to respond to each of the initiating events identified, and c) equipment whose spurious operation as a result of a fire will adversely affect the response of systems or functions required to respond to a fire. Equipment selection must occur in close coordination with the FPRA plant response model element because the plant response model defines the initiating events to be considered in the FPRA. Selected equipment is also mapped to the fire compartments defined in the PP element. This mapping information is needed to complete the Qualitative Screening (QLS) and Fire Scenario Selection and Analysis (FSS) elements.
HIGH LEVEL REQUIREMENTS FOR EQUIPMENT SELECTION (ES)
HLR HLR Description HLR Summary (From Review)
HLR-ES-A The FPRA shall identify equipment whose All Supporting Requirements were met.
failure caused by an initiating fire including spurious operation will contribute to or otherwise cause an initiating event.
HLR-ES-B The FPRA shall identify equipment whose The plant uses the ARTAK database to list selected equipment, associated cables, failure including spurious operation would and interrelationships between them. This database has above-average tracking of adversely affect the changes, and includes detailed references to original plant drawings such as operability/functionality of that portion of electrical schematics, piping and instrumentation diagrams (P&IDs), etc.
the plant design to be credited in the FPRA. Spurious operation is included in the analysis to at least the level of 2 spurious operations for valves in series and spurious operation of all valves was analyzed for the case of multiple valves in parallel.
HLR-ES-C The FPRA shall identify instrumentation The plant identified instrumentation that could affect the reliability of operator whose failure including spurious operation actions during a fire event. A simulator review was conducted, resulting in 6 would impact the reliability of operator instruments being added to the equipment list, based in part on errors made by actions associated with that portion of the operators during scenarios.
plant design to be credited in the FPRA.
A "list of safe shut down (SSD) devices affected by valid process parameters" was provided to the inspection team with ES, ICS, and ICCM groups of instruments.
HLR-ES-D The FPRA shall document the FPRA The ARTRAK database provides excellent documentation of the equipment
HIGH LEVEL REQUIREMENTS FOR EQUIPMENT SELECTION (ES)
HLR HLR Description HLR Summary (From Review) equipment selection, including that selection, including the reference material that the information was originally information about the equipment obtained from, and a detailed change history including who made the change, the necessary to support the other FPRA date of the change, and a brief synopsis of the change made.
tasks (e.g., equipment identification; equipment type; normal, desired, failed states of equipment; etc.) in a manner that facilitates FPRA applications, upgrades, and peer review.
SUPPORTING REQUIREMENTS FOR EQUIPMENT SELECTION SR Level Observation Basis Cap Cat ES-A1 Summary Verified safety significant components including Met affects of spurious operations such as pilot operated relief valves (PORVs), Block valves, Emergency Feedwater, Aux Servicewater (Feeds SG), Feedwater, HP Injection Pumps (Charging and Injection), Reactor Head Vents, Reactor Sample valves, Reactor Coolant Make-up Pumps (RCP Seal Cooling), Component Cooling pumps, Low Pressure Service Water Cooling, Circulating W(CCW), Letdown valves, Containment Spray, Low Pressure Safety Injection./ Shutdown Cooling, Power (4KV, Load Centers, motor control centers (MCCs), direct current (DC) Buses, alternating current (AC) Emergency), safe shutdown facility (SSF) Diesel Water Cooling (From component cooling water (CCW)), and Keowee are included in ARTRAK.
ES-A2 Summary Reviewed Pressurizer Relief Valve 3RV-67 Met interlock circuit for K3 and K4 contacts. All required additional equipment for this interlock circuit is in ARTRAK. Reviewed HP Injection Pumps 3HP-23 and 3HP-98 for power feed circuits.
All MCC, Load Center, and 4KV required equipment is in ARTRAK.
ES-A3 Summary Ensured safety significant components not Met including affects of spurious operations such as PORVs, Block valves, Emergency Feedwater, Aux Servicewater (Feeds SG), Feedwater, HP Injection Pumps (Charging and Injection), Reactor Head Vents, Reactor Sample valves, Reactor Coolant Make-up Pumps (RCP Seal Cooling), Component Cooling pumps, Low Pressure Service Water Cooling, Circulating W(CCW), Letdown valves, Containment Spray, Low Pressure Safety Injection./ Shutdown Cooling, Power (4KV, Load Centers, MCCs, DC Buses, AC Emergency), SSF Diesel Water Cooling (From CCW), and Keowee are included in ARTRAK.
ES-A3 Summary (internal events SR referenced by ES-A3) Met IE-C4 Previously screened initiating events, from the ONS PRA Initiating Event analysis [6] were re-evaluated for applicability to the FPRA. The complete list of candidate initiating events that were reviewed as part of the initial Level 1 PRA development was reviewed once again to determine if: 1) The Initiating Event can result from a fire? 2) The Initiating Event is more likely as a result of a fire? 3) The consequences of the fire-induced Initiating Event are worse than assumed in
SUPPORTING REQUIREMENTS FOR EQUIPMENT SELECTION SR Level Observation Basis Cap Cat the Level 1 PRA?
Based on this review, several potential initiating events were identified. These were added as new sequences or were already identified from the MSO review by the Expert Panel ES-A4 Summary Reviewed OCONEE FPRA Documentation File 3 031408 Component Selection Attachment D (Kiang Zee explained # of spurious actuations applicability in table), Multiple Spurious Considerations, 51-5044354-001 OCONEE App R Analysis U 2 & 3, and the ARTRAK Cable Database and determined that the FPRA model includes additional equipment based on the consideration of cases where up to two spurious operations of equipment alone or in combination with other fire induced loss of function failures could cause an initiating event associated with the affected equipment considering
- fire-induced initiating events treated in the Fire Safe Shutdown/Appendix R analysis,
- Internal Events PRA initiators as identified using the IE requirements in ASME-RA-2002/RA-Sb-2005 [2] (including any gradations across capability categories in that standard) as modified per the PRM requirements of this standard, or
- unique fire-induced initiating events not addressed or otherwise screened from the above two analyses if SR IE-C4 in ASME-RA-2002/RA-Sb- 2005 [2] cannot be met (See ES-A3/4-IE-C4)
ES-A5 Summary Reviewed OCONEE FPRA Documentation File 3 031408 Component Selection Attachment D (Kiang Zee explained # of spurious actuations applicability in table), Multiple Spurious Considerations, 51-5044354-001 OCONEE App R Analysis U 2 & 3, and the ARTRAK Cable Database and determined that the PRA model includes the consideration of up to and including three spurious actuations of equipment alone or in combination with other fire-induced loss of function failures for the special case where fire-induced failures could contribute not only to an initiating event but also simultaneously (a) affects the operability/
functionality of that portion of the plant design to be credited in response to the initiating event in the Fire PRA or (b) results in an initiating event where the mitigating function is not addressed in the Fire Safe Shutdown/Appendix R Analysis or (c) results
SUPPORTING REQUIREMENTS FOR EQUIPMENT SELECTION SR Level Observation Basis Cap Cat in a loss of reactor coolant system integrity.
ES-A6 Summary Reviewed OCONEE FPRA Documentation File 3 031408 Component Selection Attachment D (Kiang Zee explained # of spurious actuations applicability in table), Multiple Spurious Considerations, 51-5044354-001 OCONEE App R Analysis U 2 & 3, and the ARTRAK Cable Database and determined that the PRA model includes the consideration of up to four spurious actuations of equipment alone or in combination with other fire-induced loss of function failures for the special case where fire-induced failures could contribute to an initiating event that in turn leads to core damage and a large early release as addressed in SR ES-B4.
ES-B1 The ARTAK data base, originally built for Appendix 3 R equipment only, has been updated to include all Internal Events equipment as well.
ES-B2 Equipment was identified and listed in the ARTAK 2 database. All cables that can affect equipment, either by de-energization or by spurious operation, are listed in ARTRAK. PRA analysts would evaluate the function of the cable relative to failure mode. This is documented in the "altered events" section of the (PDF) and the FRANC database.
Considering flow paths and valves, when equipment selection was done, up to 2 valves were included for flow diversion, but for valves in parallel ALL parallel paths were considered. (ONP does not use trains in their equipment list.)
ES-B3 Additional equipment was added to the Appendix R Met and Internal Events lists according to the Oconee FPRA report dated 02.20.08, specifically an expert group studied unique fire-induced equipment failures, and an analysis of PRA supporting analysis: PRA screening analysis, IS-LOCA analysis, and containment isolation system analysis. The expert panel added 5 equipment items listed in Table 9-3 of the Oconee FPRA report.
ES-B4 The plant identified the 4 Main Coolant Pump seal 1 return isolation valves as additions to the equipment list based on IS-LOCA analysis.
ES-B5 Entries in the ARTAK data base include power Met supply, interlock circuits, instrumentation and support system dependencies ES-B6 Plant opted not to screen out equipment using this Met technique.
ES-C1 Summary The instrumentation identified was that needed to Met provide the cues necessary to initiate the actions whose failure is captured in the HFEs. This is
SUPPORTING REQUIREMENTS FOR EQUIPMENT SELECTION SR Level Observation Basis Cap Cat sufficient to support the quantification approach used for the HEPs. Errors of commission are not included in the internal events model, and are not included in the fire PRA model.
However, if the quantification of the execution errors were to be revised to a more detailed, e.g.,
THERP like method, that uses a formal task analysis, it should be recognized that other instruments should be reviewed. For example, in the switchover to sump recirculation (Enclosure 5.12 to EP/3/A/1800/001) there are steps that could lead to undesired operator actions. An example is step 29, if valve 3LP-19 could not be verified to be open, the response not obtained (RNO) is to stop the 3ALPI pump. In this case, it is probably not a significant issue, since there are redundant paths, and in all likelihood, the cables for indications are collocated with those controlling the valves. This comment is included here for completeness and not intended to suggest that additional work is required at this time. Such an activity would be beyond the current state of practice.
ES-C1 A simulator review was conducted, resulting in 6 instruments being added to the equipment list, based in part on errors made by operators during scenarios.
A "list of SSD devices affected by valid process parameters" was provided, with ES, ICS, and ICCM groups of instruments.
ES-C2 Summary The identification of instruments performed in the 2 ES task is independent of failure mode. Only a limited number of instruments were added to those on the SSEL (see section 9.7 0f OSC-8978). In many cases the argument was made that there was sufficient redundant or diverse instrumentation to provide the operators with the information needed to perform the required actions.
ES-D1 Summary The ARTAK database models FPRA equipment Met such that:
- it is clear which equipment will be associated with determining initiating events in the FPRA plant response model for the postulated fires,
- the equipment and its failures including spurious operation or indication can be modeled appropriately (for required equipment only),
SUPPORTING REQUIREMENTS FOR EQUIPMENT SELECTION SR Level Observation Basis Cap Cat
- cables associated with the equipment can be identified,
- failure modes of interest for the equipment are clear so as to support circuit analyses if required, and Table 9.5 of FPRA Summary Report NUREG/CR-6850 Task 16 Revision D documents
- justifications with regard to equipment considered but screened out of the FPRA including when meeting SR ES-A3 relevant to meeting SR IE-C4 in the ASME PRA Standard for initiating events, meeting SR ES-B6 for the mitigating equipment to be credited in the FPRA, and using the exception under SR ES-C2 for instrumentation considerations.
CABLE SELECTION ELEMENT This element identifies (and locates) (a) cables that are required to support the operation of FPRA equipment selected (see element ES), and (b) cables whose failure could adversely affect credited systems and functions. This element includes an assessment of cable failure modes and effects including consideration of fire-induced spurious operations. Equipment failure mode information is used in the Plant Response Model (PRM) element to ensure that all potentially risk-relevant equipment failure modes are included in the plant response model (e.g., loss of function failures versus spurious operation). Selected cables are also mapped to the fire compartments defined in the PP element. This mapping information is needed to complete the Qualitative Screening (QLS) and Fire Scenario Selection and Analysis (FSS) elements.
HIGH LEVEL REQUIREMENTS FOR CABLE SELECTION AND LOCATION (CS)
HLR HLR Description HLR Summary (From Review)
HLR-CS-A The FPRA shall identify and locate the plant cables whose All Supporting Requirements were met.
failure could adversely affect credited equipment or functions included in the FPRA plant response model, as determined by the Equipment Selection process (HLR-ES-A, HLR-ES-B, and HLR-ES-C).
HLR-CS-B The FPRA shall (a) perform a review for additional circuits Plant personnel self-identified some issues with overcurrent that are either required to support a credited circuit (i.e., coordination during the inspection. The plant is working to resolve per HLR-CS-A) or whose failure could adversely affect a issues with molded-case circuit breaker instantaneous overcurrent credited circuit, and (b) identify any additional equipment tripping coordination.
and cables related to these additional circuits consistent with the other equipment and cable selection requirements of this Standard.
HLR-CS-C The FPRA shall document the cable selection and location The cables associated with a particular equipment item are listed with process and results in a manner that facilitates FPRA the item in ARTAK. The ARTRAK database facilitates FPRA applications, upgrades, and peer review. applications, upgrades, and peer review, allowing the user to "fail" a cable or component, or specify failure of all equipment in a particular Fire Compartment, from this it will provide any additional equipment that is taken out of service or impaired by the postulated failures. The ARTAK database includes reference to original plant documents such as P&I Drawings for cable routing and for which cables are connected to an equipment The ARTAK database maintains a record of all changes, including which authorized user made the change and when it was made.
SUPPORTING REQUIREMENTS FOR CABLE SELECTION SR Level Observation Basis Cap Cat CS-A1 Summary The ARTRAK database has a list of all power, Met input, output, and sensing cables for each equipment item. Ensured cables whose fire-induced failure could adversely affect selected equipment and/or credited functions in the FPRA plant response model are in the FPRA model.
Reviewed cables related to PORVs, Block valves, Emergency Feedwater, Aux Service water (Feeds SG), Feedwater, HP Injection Pumps (Charging and Injection), Reactor Head Vents, Reactor Sample valves, Reactor Coolant Make-up Pumps (RCP Seal Cooling), Component Cooling pumps, Low Pressure Service Water Cooling, Circulating W(CCW), Letdown valves, Containment Spray, Low Pressure Safety Injection./ Shutdown Cooling, Power (4KV, Load Centers, MCCs, DC Buses, AC Emergency), SSF Diesel Water Cooling (From CCW), and Keowee and determined cables are included in ARTRAK.
Reviewed Pressurizer Relief Valve 3RV-67 for cables associated with relays K3 and K4 (Pressurizer Level and Pressure) instrumentation to determine if cables are modeled in the FPRA.
As per referenced drawings and ARTRAK Cable database K3 and K4 cables were considered in the FPRA model.
CS-A2 Summary Reviewed referenced drawings and License Met Amendment Correspondence dated 1981-04-30.
An additional circuit failure mode has been identified for valves 3HP-3, 3HP-23, 3HP-98, and 3LP1. This failure mode has not been identified previously and is not modeled into the FPRA. For each valve a short across the open or close limit switch combined with operator action and a seal-in circuit across the hand switch results in opening or closing the valve into the seat or yoke such that the valve could be damaged and become jammed as per IN 92-18. License Amendment correspondence dated 1981-04-30 for valves LP-1 and HP-3 stated that for a Containment fire the control power cannot be applied inadvertently.
Contrary to this operator action combined with fire effects and a seal in circuit as described above may result in valve damage and the valve being inoperable.
This scenario is not a significant contributor since operator action must coincide with an unknown
SUPPORTING REQUIREMENTS FOR CABLE SELECTION SR Level Observation Basis Cap Cat fire which has a very low occurrence probability as per Kiang Zee.
CS-A2 PIP G-97-00059 documented Oconee's IN 92-18 issues. The cable analysis given in the PIP needs to agree with the licensees recent Armored Cable Testing. For a Control Room fire and for the limited number of components reviewed, limit switches as described in the PIP do protect the circuits from IN 92-18 effects except for cables that service multiple components. For a MCC related fire, the cables from the Control Room and Valve terminate at the MCC and then are routed in wire bundles. It has not been demonstrated that a fire at or near the MCC would not cause conductor damage and cause valve damage resulting in non-recoverable damage to motor operated valves (MOVs).
This IN 92-18 issue is not a FPRA concern since these cable faults are all identified in the model and only eliminated when the respective failures are adequately justified and only if risk levels are high for a given scenario as per Kiang Zee.
CS-A2 Reviewed Oconee FPRA Documentation File 031408 Component Selection Attachment D (Kiang Zee explained # of spurious actuations applicability in table), Multiple Spurious Considerations, 51-5044354-001 OCONEE App R Analysis U 2 & 3, and the ARTRAK Cable Database for circuits whose fire-induced failure of one or two or more cables due to multiple hot shorts (intra-cable and inter-cable), by themselves, could adversely affect selected equipment due to spurious operation(Not applicable for IN 92-18 circuits). Reviewed cables related to PORVs, Block valves, Emergency Feedwater, Aux Service water (Feeds SG),
Feedwater, HP Injection Pumps (Charging and Injection), Reactor Head Vents, Reactor Sample valves, Reactor Coolant Make-up Pumps (RCP Seal Cooling), Component Cooling pumps, Low Pressure Service Water Cooling, Circulating W(CCW), Letdown valves, Containment Spray, Low Pressure Safety Injection./ Shutdown Cooling, Power (4KV, Load Centers, MCCs, DC Buses, AC Emergency), SSF Diesel Water Cooling (From CCW), and Keowee and determined analysis results are included in ARTRAK.
CS-A3 Summary Reviewed Pressurizer Relief Valve 3RV-67 for Met
SUPPORTING REQUIREMENTS FOR CABLE SELECTION SR Level Observation Basis Cap Cat cables associated with relays K3 and K4 (Pressurizer Level and Pressure) instrumentation to determine if cables are modeled in the FPRA.
As per referenced drawings and ARTRAK Cable database K3 and K4 cables were considered in the FPRA model.
Reviewed HP Injection Pumps 3HP-23 and 3HP-98 for power feed circuits. All MCC, Load Center, and 4KV required cables are in ARTRAK.
CS-A4 Summary OCONEE FPRA Documentation File 031408 Met Cable Selection Sections 3.2 and 3.3 may not have considered manual actions when transferring from Normal Power to Alternate Power in the FPRA model.
FPRA model does not credit Bus transfer scenarios that require manual actions as per Kiang Zee.
CS-A4 Reviewed Pressurizer Relief Valve 3RV-67 cables associated with relays K3 and K4 (Pressurizer Level and Pressure) instrumentation to determine if the adverse fire effects are modeled in the FPRA. As per referenced drawings and ARTRAK Cable database K3 and K4 cable adverse fire effects were considered in the FPRA model.
Reviewed high pressure (HP) Injection Pumps 3HP-23 and 3HP-98 for power feed circuit adverse fire effects. All MCC, Load Center, and 4 kilo-volt (KV) required cable adverse fire effects are in ARTRAK.
CS-A5 Summary Reviewed circuits whose cable conductor-to- Met ground and conductor-to-conductor shorts (both intra-cable and inter-cable) as potential could adversely affect FPRA equipment. Reviewed cables related to PORVs, Block valves, Emergency Feedwater, Aux Service water (Feeds SG), Feedwater, HP Injection Pumps (Charging and Injection), Reactor Head Vents, Reactor Sample valves, Reactor Coolant Make-up Pumps (RCP Seal Cooling), Component Cooling pumps, Low Pressure Service Water Cooling, Circulating W(CCW), Letdown valves, Containment Spray, Low Pressure Safety Injection./ Shutdown Cooling, Power (4KV, Load Centers, MCCs, DC Buses, AC Emergency), SSF Diesel Water Cooling (From CCW), and Keowee and determined analysis results are included in ARTRAK.
SUPPORTING REQUIREMENTS FOR CABLE SELECTION SR Level Observation Basis Cap Cat CS-A6 Summary Reviewed circuit failure modes associated with Met the effects of circuits de-energizing as a result of the design operation of overcurrent protective devices responding to fire-induced cable short circuits that could adversely affect FPRA equipment. Reviewed cables related to PORVs, Block valves, Emergency Feedwater, Aux Service water (Feeds SG), Feedwater, HP Injection Pumps (Charging and Injection), Reactor Head Vents, Reactor Sample valves, Reactor Coolant Make-up Pumps (RCP Seal Cooling), Component Cooling pumps, Low Pressure Service Water Cooling, Circulating W(CCW), Letdown valves, Containment Spray, Low Pressure Safety Injection./ Shutdown Cooling, Power (4KV, Load Centers, MCCs, DC Buses, AC Emergency), SSF Diesel Water Cooling (From CCW), and Keowee and determined analysis results are included in ARTRAK.
CS-A7 Summary As per NUREG/CR-6850 (pages 9-9) "Case 3: Met Armored cable or cable in dedicated conduit.
Three-phase proper polarity faults are not considered credible for armored power cable or a single triplex cable in a dedicated conduit. The basis for exclusion is that multi-conductor-to-multi-conductor hot shorts are not plausible given the intervening grounded barrier (i.e., the armor or conduit)." Since all applicable 3 phase cables are armored cables at OCONEE 3, this requirement is met.
CS-A8 ONS uses armored cables with thermoset Met insulation exclusively inside containment. Per FPRA Cable Selection Report NUREG/CR-6850 Task 3 R0237-05-0001.03: "The basis for excluding spurious operation as a result of a fire in containment is due to a combination of: 1) inter-cable hot shorts involving armored cables are not considered credible, and 2) intra-cable hot shorts involving heater control power or lamp control power conductors located downstream of the MCC are not capable of energizing the coil."
CS-A9 Summary Scenarios requiring two proper polarity inter-cable Met hot shorts on an ungrounded DC system (e.g.,
repositioning of a DC powered valve with the breaker for the DC circuit open where the only cable in the area is associated with the DC power cable) were not considered credible for thermoset insulated armored cables. However, wire bundles inside panels or cabinets should consider this failure mode since it is not IAW RIS 2004-03.
SUPPORTING REQUIREMENTS FOR CABLE SELECTION SR Level Observation Basis Cap Cat Circuits are identified in FPRA model. Fire initiators at the cabinets or panels would consider these fire effects as per Kiang Zee. .
CS-A10 Summary Specific information on cable routing through fire 1 compartments is available in the ARTAK database, specifically including both ends of the cable, and raceways, with the exception of the "Y2" components, where cable location is TBD, and the "Y3" components, where cable routing information is considered to not be worth the effort necessary to obtain it. Quote from the Cable Selection Report: "In order to facilitate the compartmental analysis, the cable information has been segregated into fire compartments that are made up of one or more Appendix R fire zones. In some cases, the fire compartments cannot be defined as having an enclosed fire boundary.
Accordingly, a given scenario may identify one or more targets that are not in the same zone as the ignition source. In this case, it will be necessary to add the cables associated with each target (e.g.,
cable tray) to the zone in order to adequately address the attendant component failures associated with the given scenario."
CS-A11 Summary Cable routing is assumed for "Y3" group cables. Met Cables are sorted into Y1 (Credited in safe shutdown analysis, known location) Y2 (Credited in safe shutdown analysis, TBD location), and Y3 components linked to one or more PRA basic events that will be assumed to be failed in every compartment in lieu of assembling the cable routing information necessary to credit their operation in the event of a fire.
CS-B1 Finding Plant personnel self-identified some issues with F&O CS-B1-1 Not Met overcurrent coordination during the inspection.
The plant is working to resolve issues with molded-case circuit breaker instantaneous overcurrent tripping coordination.
CS-C1 Summary The cables associated with a particular equipment Met item are listed with the item in ARTAK. The ARTRAK database facilitates FPRA applications, upgrades, and peer review, allowing the user to "fail" a cable or component, or specify failure of all equipment in a particular Fire Compartment, from this it will provide any additional equipment that is taken out of service or impaired by the postulated failures.
CS-C2 Summary The ARTAK database includes reference to Met original plant documents such as P&I Drawings
SUPPORTING REQUIREMENTS FOR CABLE SELECTION SR Level Observation Basis Cap Cat for cable routing and for which cables are connected to an equipment The ARTAK database maintains a record of all changes, including which authorized user made the change and when it was made.
CS-C3 Summary The general assumed cable routing for these "Y3" Met components is given in tables and text in section 2.3 of the reference document - FPRA Cable Selection Report NUREG/CR-6850 Task 3 (R0237-05-0001.03t): This cable selection report states: "...the Y3 entry is presumed failed unless specifically excluded for a given compartment or scenario. This is generally a much less rigorous process than assembling the cable information for a component or a group of components that comprise a system." Use of the provision of SR CS-A11is inherently a judgment call, the examples cited in the report seem to be reasonable applications of this exemption CS-C4 Finding No specific documentation of overcurrent F&O CS-C4-1 Not Met coordination was provided during the inspection. .
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/20/2008 ID Number :CS-B1-1 Level of Significance: Finding Reviewer: MXM Capability Category: Not Met OBSERVATION:
Plant personnel self-identified some issues with overcurrent coordination during the inspection.
The plant is working to resolve issues with molded-case circuit breaker instantaneous overcurrent tripping coordination.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Breaker Coordination Study, OSC3120, Kiang Zee rev 13 David Goforth
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/20/2008 ID Number :CS-C4-1 Level of Significance: Finding Reviewer: MXM Capability Category: Not Met OBSERVATION:
No specific documentation of overcurrent coordination was provided during the inspection. This conclusion is subject to revision whenever documentation is provided by the plant.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
QUALITATIVE SCREENING ELEMENT This element identifies fire compartments that can be assumed to have little or no risk significance without quantitative analysis.
(QLS only considers compartments as individual contributors. All compartments are reconsidered as a part of the multi-compartment fire scenario analysis (see HLR-FSS-E.) Qualitative screening is based on the fire compartments defined in element PP and on the equipment and cable location information provided by elements ES and CS. Any fire compartment that fails to satisfy the qualitative screening criteria is retained for further analysis.
HIGH LEVEL REQUIREMENT FOR QUALITATIVE SCREENING (QLS)
HLR HLR Description HLR Summary (From Review)
HLR-QLS-A The FPRA shall identify those physical analysis units that Initial boundary is Owner Controlled area. Building and structure screen out as individual risk contributors without level physical analysis units (PAUs) identified and qualitatively quantitative analysis. screened out. One SR not met because resolution of 4 PAUs not finalized.
HLR-QLS-B The FPRA shall document the results of the qualitative Extensive tables identifying final disposition of all PAUs and ignition screening analysis in a manner that facilitates FPRA sources (aside from 4 PAUs unresolved).
applications, upgrades, and peer review.
SUPPORTING REQUIREMENTS FOR QUANTITATIVE SCREENING SR Level Observation Basis Cap Cat QLS- Summary 18 Buildings/structures qualitatively screened Met A1 out. Maintenance Support Bldg, Service Bldg, Admin Bldg, and cluster of building north east of plant identified for further analysis but no further analysis identified.
QLS- Summary Building/Structure screening criteria explicitly Met A2 described on page 22 (building PAU screening) of OSC-8979. Criteria include, fire in PAU does not lead to plant trip or require TS shutdown, and does not fail PRA or safe shutdown component.
QLS- Finding 22 buildings structures screened, 4 left F&O QLS-A3-1 Not Met A3 unresolved.
QLS- Summary Qualitative screening of ignition sources Met A4 resulted in excluding some sources from development if ignition source itself is not credited and it cannot impact credited targets (no local definition of "credited" but most likely components that are in the PRA or safe shutdown lists).
QLS- Summary Screening criteria explicitly described on page Met B1 22 (building PAU screening) and page 3 (ignition source screening). Fire in PAU does not lead to plant trip or require TS shutdown, and does not fail PRA or safe shutdown component. Ignition source screening if source is not a target and no PRA targets can be affected.
QLS- Summary Extensive tables identifying final disposition of Met B2 all PAUs and ignition sources (aside from 4 buildings unresolved).
QLS- Summary Buildings and ignition sources screened out Met B3 identified as well as criteria used.
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/17/2008 ID Number :QLS-A3-1 Level of Significance: Finding Reviewer: SCD Capability Category: Not Met OBSERVATION:
Disposition of 4 building/structure PAUs left as unresolved after initial qualitative screening.
These include The Maintenance Support Bldg, Service Bldg, Admin Bldg, and cluster of building north east of plant. These 4 were left for further analysis but no further analysis was idenitifed.
BASIS FOR LEVEL OF SIGNIFICANCE:
The qualitative screening was incomplete so the SR was not met.
POSSIBLE RESOLUTION (REVIEWER):
Complete the evaluation of the four buildings either in qualitative or quantitative screening, or include in the FPRA.
Reference(s): Personnel Contacted:
- 1. OSC-8979
PLANT RESPONSE MODEL ELEMENT This element involves the development of a logic model that reflects the plant response following a fire. The FPRA plant response model is central to the quantification of fire risk and is exercised in the Fire Risk Quantification (FQ) element to quantify conditional core damage probability (CCDP) and conditional large early release probability (CLERP) values for selected fire scenarios. This model is commonly constructed based on an Internal Events PRA model that is then modified to include only those initiating events that can result from a fire, to include unique additional equipment failure modes, such as spurious operation, not addressed in an Internal Events PRA model, and to reflect fire-specific plant procedures and operator actions (e.g., alternate and remote shutdown actions).
HIGH LEVEL REQUIREMENTS FOR FIRE PRA PLANT RESPONSE MODEL (PRM)
HLR HLR Description HLR Summary (From Review)
HLR-PRM-A The FPRA shall include the FPRA plant Large fault tree model capable of collecting inputs and estimating fire CDFs and response model capable of supporting the LERFs by combining equipment failures with ignition frequencies in the logic HLR requirements of FQ. model. However, resolution of the findings from the Maracor review has not been completed and needs to be completed.
HLR-PRM-B The FPRA plant response model shall include The net change from the internal events PRA (including a Fire Event tree fire-induced initiating events, both fire-induced developed in 2005) to the 2008 integrated model needs to be fully explained and random failures of equipment, fire-specific and documented as part of the FPRA report. Although some of the FPRA as well as non-fire related human failures documentation discussed new logic modes and scenarios, utility and contractor associated with safe shutdown, accident PRA personnel stated repeatedly that no new logic models were needed. Both progression events (e.g., containment failure would be correct if the documentation on new models and scenarios dealt with modes), and the supporting probability data evaluations that were performed, but the results of the evaluations were that it (including uncertainty) based on the SRs was not necessary to actually change the logic models. These results and provided under this HLR that parallel, as conclusions were not, however, provided in the documentation.
appropriate, the ASME PRA Standard for Internal Events PRA.
- The 2005 PRA introduced several fire ignition sources (e.g., cable shaft, turbine building, 4 kv switchgear) that were mapped into the existing accident sequence (and event tree) initiated by a HELB. The 2008 PRA modified some of these ignition sources, introduced others mapping into the ones that remained after the modification, and created new ones that were mapped into existing accident sequences (and event trees) initiated by various transients. One in particular is a spuriously-actuated deboration. Both the 2005 and 2008 modifications should be viewed collectively as transforming the internal events PRA into an integrated model that includes fire. The net change from the 2005 internal events PRA to the 2008 integrated model needs to be fully explained and documented as part of the FPRA report. Included would be explanation as to which sequences (i.e., event tree branches) for ignition sources (such as %CSFIRE) were modeled and why some sequences (branches)
HIGH LEVEL REQUIREMENTS FOR FIRE PRA PLANT RESPONSE MODEL (PRM)
HLR HLR Description HLR Summary (From Review) produced by the event tree leading to core damage were apparently not modeled.
HLR-PRM-C The FPRA plant response model shall be Expert panel met and identified potential new scenarios caused by spurious expanded to include new contributors operation but, according to utility and contractor personnel, no changes were because of additional spurious operation needed to the PRA.
considerations following a review of the results produced in meeting Section 4.16 of this Standard.
HLR-PRM-D The FPRA shall document the FPRA plant The documentation is incomplete and inconclusive. New, fire specific failure response model in a manner that facilitates modes and potential changes are discussed throughout the documents but the FPRA applications, upgrades, and peer final resolution of these evaluations is not clear and sometimes contradicts what review. the utility and contractor personnel stated.
SUPPORTING REQUIREMENTS FOR PLANT RESPONSE MODEL SR Level Observation Basis Cap Cat PRM-A1 Summary Model results in tables providing PRA results F&O PRM-B1-1 Met for fire ignition source (or PAU) specific CCDPs and CLERPS.
PRM-A2 Summary Large fault tree model capable of collecting F&O PRM-B1-1 Met inputs and estimating fire CDF and LERFs by combining equipment failures with ignition frequencies in the logic model. However, resolution of the findings from the Maracor review has not been completed and needs to be completed.
PRM-A3 Summary Clear link between PAU/ignitions source and F&O PRM-B1-1 Met results, must go the cut-set files to identify which initiating event was caused by each ignition source.
PRM-A4 Summary Used the suite of codes and types of basic Met events that they used for the internal events, uncertainty propagation should be the same.
PRM-A5 Summary All Equipment and cable location for all PRA, Met safe shutdown, and plant trip equipment identified and documented, or assumed to be failed.
PRM-A6 Summary Cables and equipment linked to logic models Met through appropriate basic events for all important sequences and ignition source PRM-B1 Finding Oconee used a version of the internal events F&O PRM-B1-1 Not Met model with a substantial number of outstanding issues (see F&O IEPRA-1) as the base model. The finding is based on the fact that the issues identified in the peer review have not been resolved.
PRM-B2 Summary As per R0237-05-0001.5, Rev. G, "Special Met cases also required the application of unique fire-specific initiators such as %CSFIRE for cable shaft fire scenarios and %TB0FIRE for the Control Room abandonment scenarios."
However, as these and the new fire-specific initiator for deboration (%T-DEBOR) are ultimately mapped directly to existing accident sequences initiated by existing internal events initiators (HELB for %CSFIRE and
%TB0FIRE, and Reactor Trip for %T-DEBOR), there are no new initiating events.}
Nonetheless, an expert panel met to identify the effects of multiple spurious failures, some of which could initiate Boron dilution and spurious pressurize heater operation. These events were analyzed (with MAAP) as needed, but it was determined that they could all be represented by existing initiating events.
Two unique fire initiating events (CSFIRE,
SUPPORTING REQUIREMENTS FOR PLANT RESPONSE MODEL SR Level Observation Basis Cap Cat TBOFIRE) created from the previous (2005) fire model were in the logic model but appeared to not have been used.
PRM-B3 Suggestion Although some of the FPRA documentation F&O PRM-B3-1 Met discussed new logic modes and scenarios, utility and contractor PRA personnel stated repeatedly that no new logic models were needed.
PRM-B4 Suggestion In general, fire induced initiators are modeled F&O PRM-B4-1 Met by assuming an existing transient in the model (e.g., turbine trip; loss of condenser vacuum) occurs. Rational for assigning a given initiator to each ignition source should be better developed and documented.
PRM-B4 (internal events SR referenced by PRM-B4 Met AS-A1 and PRM-B5) Update documentation of initiating events caused by each ignition source which will provide the link to the key safety functions. Clarify large fault tree structure correspondence with the graphical event tree structure, e.g., not all event tree sequences carried clearly over into large fault tree.
PRM-B4 (internal events SR referenced by PRM-B4 Met AS-A2 and PRM-B5) This SR is Met (but see PRM-B2) because any fire effects have been linked to existing internal events fault/event trees, which previously identified key safety functions.
PRM-B4 (internal events SR referenced by PRM-B4 Met AS-A3 and PRM-B5) This SR is Met (but see PRM-B2) because any fire effects have been linked to existing internal events fault/event trees, which previously identified key safety functions.
PRM-B4 (internal events SR referenced by PRM-B4 Met AS-A4 and PRM-B5) This SR is Met (but see PRM-B2) because any fire effects have been linked to existing internal events fault/event trees, which previously identified key safety functions.
PRM-B4 (internal events SR referenced by PRM-B4 Met AS-A5 and PRM-B5) This SR is Met (but see PRM-B2) because any fire effects have been linked to existing internal events fault/event trees PRM-B4 (internal events SR referenced by PRM-B4 Met AS-A6 and PRM-B5) This SR is Met (but see PRM-B2) because any fire effects have been linked to existing internal events event trees PRM-B4 (internal events SR referenced by PRM-B4 1&2
SUPPORTING REQUIREMENTS FOR PLANT RESPONSE MODEL SR Level Observation Basis Cap Cat AS-A7 and PRM-B5) This SR is Met (but see PRM-B2 and AS-A1) because any fire effects have been linked to existing internal events event trees PRM-B4 (internal events SR referenced by PRM-B4 Met AS-A8 and PRM-B5) This SR is Met (but see PRM-B2) because any fire effects have been linked to existing internal events event trees PRM-B4 (internal events SR referenced by PRM-B4 2 AS-A9 and PRM-B5) This SR is CC-II based on the link between the FPRA and internal events PRA. For the internal events PRA, SR AS-A9 was originally assigned CC-II in the 2001 Peer Review, and this is assumed applicable here as well (but see PRM-B2)
PRM-B4 (internal events SR referenced by PRM-B4 2 AS-A10 and PRM-B5) This SR is capability category 2 (but see PRM-B2) because any fire effects have been linked to existing internal events fault/event trees PRM-B4 (internal events SR referenced by PRM-B4 N/A AS-A11 and PRM-B5) This SR is N/A because the Oconee model does not use transfers between event trees PRM-B4 (internal events SR referenced by PRM-B4 Met AS-B1 and PRM-B5) The CC = Met is consistent with the 2006 Maracor Peer Review of the Oconee-3a PRA model.
PRM-B5 Summary This SR is Met (but see PRM-B2) because fire Met effects have been linked to existing internal events fault/event trees, which previously identified key safety functions and no new models were need (but see PRM-B3 regarding discovery of fire specific initiating events and PRM-b about use or non-use of 2005 fire event tree).
PRM-B6 Summary Identified events demonstrate a search Met (concentrating on spurious events) that included potential changes to timing and other mitigating requirements (i.e., success criteria).
There remains some inconsistency in documentation with some statements that no new models were needed while others state, for example, new initiator and structure added.
PRM-B7 Summary Addition of pressurizer heaters and sprays to Met fire plant response models discussed but probably not added because scenarios enveloped by existing internal events.
Deboration determined to be unimportant
SUPPORTING REQUIREMENTS FOR PLANT RESPONSE MODEL SR Level Observation Basis Cap Cat because only important during shutdown and not added.
PRM-B8 Suggestion Although some documents indicated that new F&O PRM-B8-1 Met models were properly developed, utility and contractor statements that none of these models needed to be added.
PRM-B9 Summary Oconee located all cables required to operate Met equipment. Cable location for some cables was not identified if it was assumed that the supported components always fail after a fire (called an Y3 component). If necessary, Y3 component failures could be removed from the guaranteed failed list by reviewing specific fire target set and excluding the component and its cables from the targets.
PRM-B10 Summary Existing HRA actions reviewed for applicability Met PRM-B11 Summary No failure events required re-analysis given Met the fire context (excluding human actions).
Hot short probabilities that are not included in the internal events PRA were assigned to new events or existing events, and failed equipment for each fire ignition source identified and assigned Failed PRM-B12 Summary Only hot short probabilities assigned. Fire N/A failed equipment assigned a failed state.
PRM-B13 Summary Existing ISLOC analyses reviewed and new Met containment bypass events were added as needed.
PRM-B14 Summary No new ISLOCA sequences identified that Met lead to new accident sequences, only new failures added to existing sequences.
PRM-C1 Comment Problem with Fire PRA Standard N/A on Standard PRM-D1 Finding Final documentation should identify and F&O PRM-D1-1 Not Met clearly describe all fire related changes made to the internal event PRA in one document to meet the standard. The current documentation provides an incomplete and sometimes contradictory description of proposed changes versus real changes.
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :PRM-B1-1 Level of Significance: Finding Reviewer: SCD Capability Category: Not Met OBSERVATION:
The most recent "peer review" was performed in 2006 by Maracor on Rev. 3a of the Oconee PRA, developed in March 2005. The Maracor team identified numerous issues although they did not specifically characterize these as F&Os, nor did they assign severity levels.
The peer review also identified 159 Partially met Cat II, 103 not met cat II, 21 Cat I, and 23 Indeterminate supporting requirements. From these Oconee identified 60 not-met and partially met internal events supporting requirements unresolved (others determined to be invalid).
Oconee classified 31 of these as important to Fires.
In addition, it is not clear whether the fire event trees introduced in revision 3a to the Oconee PRA have been reviewed.
BASIS FOR LEVEL OF SIGNIFICANCE:
There are numerous unresolved issues regarding the technical adequacy of the internal events PRA that Oconne used as their baseline model. All the logical modelling and event quantification into which the fire PRA OR3a)
POSSIBLE RESOLUTION (REVIEWER):
RG 1.200 calls for resolution of all issues identified in Peer reviews before use of a PRA in a given application. Resolution may include a conclusion that the issue need not be resolved because it has minimal or no affect on the particular application.
Reference(s): Personnel Contacted:
- 1. 2006 Maracor Oconee-3a PRA Peer Brandi Weaver Review & Oconee Draft Response Table Rob Boyer (as per Rob Boyer, Attachment 2)
- 2. The 60 ASME SRs that are not fully met for Oconee
- 3. Results and Insights from Oconee PRA Revision 3a
- 4. Oconee Rev 3a. F & O Status
- 5. XSAA-115, Rev. 10
- 6. OSC-9068, Rev. 1
- 7. XSAA-101
- 8. NED-A08-7
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :PRM-B3-1 Level of Significance: Suggestion Reviewer: SCD Capability Category: Met OBSERVATION:
As per R0237-05-0001.5, Rev. G, "[t]he application of the fire-specific initiators was limited and the applicable scenario results were compared to results assuming more commonly used initiators." Review of the or3a_FIRE_CDF.caf file indicates that at least seven of these types of fire-specific initiators are present in the model: %C4KVFIRE, %CLPIHATCH, %CPENROOM,
%CSFIRE, %TB0FIRE, %SBOFIRE and %T-DEBOR. As per OSC-8979, Rev. 1, "[a]n event tree for fire initiating events has been developed and is included as Figure C-1. The top events considered in the event tree are the availability of SSHR, RCS integrity (relief valves and seal LOCAs), and HPI short and long term success. This event tree has been developed using the HELB event tree as a model." Comparison of Figure C-1 (provided separately) and the HELB event tree from the internal events model indicates that they are the same, except for the change in initiator.
BASIS FOR LEVEL OF SIGNIFICANCE:
New initiators caused by fires reportedly incorporated into existing models.
POSSIBLE RESOLUTION (REVIEWER):
Although it appears that these special fire initiators have been incorporated into the FPRA model following the same analytic process as for existing initiators, such as the cited HELB (event tree), this needs to be verified and documented in the current version of the FPRA report, not just in OSC-8979, Rev. 1, which is superseded by the current FPRA. All Internal Events SRs referenced in this SR need to be addressed.
Reference(s): Personnel Contacted:
- 1. PRA Rev 3 Fire Analysis,
- 2. OSC-8789 (2005)
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :PRM-B4-1 Level of Significance: Suggestion Reviewer: SCD Capability Category: Met OBSERVATION:
In general, fire induced initiators are modeled by generically mostly assuming T1 trip (sometimes Loss of Condenser vacuum T4 or loss of main feedwater T2) beacause it was stated that proper seqeunces are developed within the logic models given the fire inducted failures input for each calculation. Although this could work, success requires a very high technical quality in the internal event trees beacuse non-dominate sequences under random failures will become dominate. Rational for assigning each ignition to T2 or T4 was not fully consistent with utilities position that the logic models will appropraitly refelct sequences without identifying particular initiating events for each ignition source. Use of 2005 fire event tree developed to model loss of secondary side cooling and RCP seal LOCA unclear (see PRM-B2).
BASIS FOR LEVEL OF SIGNIFICANCE:
This SR is Met because components/HFEs potentially affected by fire that could cause existing initiating events were mapped to the internal events fault tree for the initiating events linked to the specific fires. The corresponding fire-affected basic events (some new, some modified from before) were integrated into the existing internal events trees (including the introduction of new gates where appropriate).
POSSIBLE RESOLUTION (REVIEWER):
Although it appears that fire initiators have been incorporated into the FPRA model following the same analytic process as for existing initiators this needs to be verified and documented in the current version of the FPRA report. A through evaluation of the results of the FPRA (not evidenced during this review) should be perfromed to confirm that the orignial models are appropriate when the previuosly non-dominated seqeunces become dominanted.
Reference(s): Personnel Contacted:
- 3. PRA Rev 3 Fire Analysis,
- 4. OSC-8789 (2005)
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/17/2008 ID Number : PRM-B8-1 Level of Significance: Suggestion Reviewer: RHG Capability Category: Met OBSERVATION:
An older 2005 fire PRA states that new EFW and SSF system models were developed that stripped out failure to run contributions from some pumps because, following fire induced initiating event, a successful EFW or SSF start could provide time needed to activate HPI to deal with upcoming seal LOCA or PORV sticking open. HPI needs to be successfully aligned within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and including long term run failures would over account for EFW and SSF failures. The utility and contractor personal were unable to unambiguously determine whether these models were incorporated into the FPRA or were not needed and not used.
The following components were cited as being added to the FPRA, but no current basic events for them were found (either new or previously existing): 3FDWP0206, -0231, -0232; 3MPS0056; 3RCPDP05, -06, -08, -09. Oconee staff explained that some had previous links to basic events, subsequently removed, while others were associated as instruments for HFEs related to subcooling margin, ultimately not incorporated into the FPRA. These explanations need to be provided.
BASIS FOR LEVEL OF SIGNIFICANCE:
Based on the utility and contractor statements that none of these models needed to be added, the Capability Category is met.
POSSIBLE RESOLUTION (REVIEWER):
Complete documentation to include the final resolution of all proposed models.
Reference(s): Personnel Contacted:
- 1. OSC-8978 Ed Simbles
- 2. FPRA CAFTA Fault Tree Model
- 3. 2006 Maracor Oconee-3a PRA Peer Review
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :PRM-D1-1 Level of Significance: Finding Reviewer: SCD Capability Category: Not Met OBSERVATION:
Oconee developed a fire PRA in 2005 and added it to their base PRA. When the current 2008 FPRA was performed, this earlier 2005 FPRA was used for selected unique fire specific initing events. There is a separate description of the development of this 2005 FPRA model. The 2008 FPRA descibes changes made to develop the FPRA, but does describe 1) the changes made in 2005 and 2) the changes made in 2008 relative to 2005.
An older 2005 fire PRA states that new EFW and SSF system models were developed that stripped out failure to run contributions from some pumps because, following fire induced initiating event, a successful EFW or SSF start could provide time needed to activate HPI to deal with upcoming seal LOCA or PORV sticking open. HPI needs to be successfully aligned within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> and including long term run failures would over account for EFW and SSF failures. The utility and contractor personal were unable to unambiguously determine whether these models were incorporated into the FPRA or were not needed because similar models were in the high energy line break event tree which is in the internal events model that was used as a basis for the FPRA.
BASIS FOR LEVEL OF SIGNIFICANCE:
The current documentation is confusing, incoplete, and inconsistent. The final FPRA docemnt include numerous discussions implyinng that model cahnges are needed (see F&O PRM-B2, PRM-B3) but the utlity and contractor personel sated that no logic model changes were needed.
The final FPRA docuemntation also did not dicsus the 2005 fire PRA aothough the fire event tree from that study was indentified in the FPRA models. Final documentation should include all fire related changes in one document to meet the standard.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
FIRE SCENARIO SELECTION AND ANALYSIS ELEMENT In this element, fire scenarios are selected, defined, and analyzed in order to represent the collection of fire events that might contribute to plant fire risk. The purpose of the fire scenario analysis is to quantify the likelihood that, given ignition of a fire, fire-induced damage to selected equipment and cables (as defined in the ES and CS elements) occurs. The result is expressed for each fire scenario as a) a set of cable and equipment failures, including specification of the failure modes, reflecting the loss of a specific set of damage targets and b) a conditional probability that given the fire, the postulated cable and equipment failures are realized (potentially including both a severity factor and a non-suppression probability). These results are fed forward to the FQ element for incorporation into the final risk calculations.
HIGH LEVEL REQUIREMENTS FOR FIRE SCENARIO SELECTION AND ANALYSIS (FSS)
HLR HLR Description HLR Summary (From Review)
HLR-FSS-A The FPRA shall select one or more All supporting requirements were met except FSS-A5, Horizontal propagation combinations of an ignition source and outside zone of influence (ZOI) not done yet, as the effects of PVC jacket (typically damage target sets to represent the fire TP) on horizontal spread is an open item self identified by Oconee. Current scenarios for each unscreened physical chemical composition of PVC jackets are being examined. There were three analysis unit upon which estimation of the suggestions also. The first dealing with hot work fires, they are not identified in all risk contribution (CDF and LERF) of the zones. For example, the Unit 3 equipment room located in the FPRA Summary physical analysis unit will be based. Report Task 16 Appendix A scenario description. Either include hot work scenario in the equipment room or provide a justification for omitting it. The second concerns solid state componets. They were not mentioned as part of target sets. The third suggestion states that Oconee has identified the need to develop additional fire scenarios to evaluate the risk for the safe shutdown facility (SSF). These scenarios and their risk contribution should be reviewed.
HLR-FSS-B The FPRA shall include an analysis of All supporting requirements were met for this HLR. One suggestion was made.
potential fire scenarios leading to the Lost degraded functions should be clearly discussed in the documentation of the MCR abandonment. control room abandonment analysis.
HLR-FSS-C The FPRA shall characterize the factors Oconee unit 3, for the most part, applies a two point model for heat release rates that will influence the timing and extent of and corresponding split fractions. Peak HRR is conservatively established initially in fire damage for each combination of an the fire scenario, and no decay modeled from fuel limitations. A thermoset damage ignition source and damage target sets criterion has been applied for the Oconee cable configuration, i.e. conductors selected per HLR-FSS-A. insulated with thermoset insulation, armored, and wrapped with a PVC jacket.
Although Oconee is collecting information regarding the PVC jacket, the current NRC position is that thermoplastic failure criteria should be applied in cases where the PVC can pool since PVC generally constitutes a thermoplastic material (see
HIGH LEVEL REQUIREMENTS FOR FIRE SCENARIO SELECTION AND ANALYSIS (FSS)
HLR HLR Description HLR Summary (From Review)
NUREG/CR-6850 Appendix H for further explanation). Regarding the heat release rates (HRRs) applied for transient combustibles, Oconee has provided a weak basis for only using the 75% HRR. This use of only the 75% HRR for transient combustibles is addressed in FSS-D. Finally, Oconee was not assessed on the requirements in the Fire PRA standard for raceway fire barriers since none are installed in Unit 3.
HLR-FSS-D The FPRA shall quantify the likelihood of The fire modeling assessments used by Oconee relied upon an approach based risk-relevant consequences for each upon Hughes Associates Generic Fire Modeling Treatments. The correlations and combination of an ignition source and CFAST used in the Hughes approach were used within their limitations to develop damage target sets selected per HLR- zone of influence regions in which fire damage was postulated to occur. Hughes FSS-A. provided technical justification for the assumptions used in its approach. Should a target be in the zone of influence, and therefore assumed damaged, Oconee postulated that the zone of influence be extended to the ceiling. Significant to the hot gas layer work done by Hughes, Oconee independently credited the fire brigade with preventing damage to cables that had not occurred within the first 20 minutes from hot gas layer. Oconee has conducted drills on fire brigade successfully applying a hose stream to fires within 20 minutes, yet they have also exceeded the 20 minute assumption. A probability needs to be established to recognize that a brigade response to interrupt damage from the hot gas layer may vary, which is also in keeping with the risk-informed approach. As identified in FSS-C, a weak basis is established for only using the 75% HRR for transient combustibles. Thus, Oconee needs to review its records with respect to the transient combustible program, including violations, to reassess the need for a higher HRR for transient combustibles as well. Walkdowns regarding zone of influence impacts were conducted using the Hughes guidance, supplemented by identifying fire structures and systems, and those walkdowns applied in the development of fire scenarios.
The following is from page 318 of the Hughes Associates Generic Fire Modeling Treatments January 5, 2007, It is readily seen that the ability to model fires near a wall or in a corner has been disabled in CFAST version 6.0.10, though this is not documented. This needs further investigation.
HLR-FSS-E The parameter estimates used in fire All supporting requirements for this HLR were met.
modeling shall be based on relevant generic industry and plant-specific information. Where feasible, generic and
HIGH LEVEL REQUIREMENTS FOR FIRE SCENARIO SELECTION AND ANALYSIS (FSS)
HLR HLR Description HLR Summary (From Review) plant-specific evidence shall be integrated using acceptable methods to obtain plant-specific parameter estimates. Each parameter estimate shall be accompanied by a characterization of the uncertainty.
HLR-FSS-F The FPRA shall search for and analyze All supporting requirements for this HLR were met risk-relevant scenarios with the potential for causing fire-induced failure of exposed structural steel.
HLR-FSS-G The FPRA shall evaluate the risk The Oconee approach to developing individual fire scenarios (i.e., the fire scenarios contribution of multi-compartment fire considered consistent with HLR-FSS-A) has inherently captured the potential effects scenarios. of fires impacting more than one physical analysis unit for partitions within the turbine building. However, the analysis has not treated potential multi-compartment fire scenarios for other combinations of physical analysis units (for example, fires involving the large oil-filled outdoor transformers could impact the turbine building or turbine building fires could impact adjacent fire areas including the main control room). As a result, a number of the Supporting Requirements associated with HLR-FSS-G have not been met.
HLR-FSS-H The FPRA shall document the results of Oconee has documented its fire scenarios, including ignition source, damage target the fire scenario and fire modeling set, and factors which determine CDF. Fire model selection, inputs, and uncertainty analyses including supporting information information for parameter uncertainty are documented in the Hughes report.
for scenario selection, underlying Consistent with the finding on PVC jackets, Oconee has not documented the impact assumptions, scenario descriptions, and on the extent of fire damage as well as on cable failure threshold. (Oconees report the conclusions of the quantitative does identify that the impact of the PVC jacket on fire damage from horizontal analysis, in a manner that facilitates FPRA propagation is an open item). No uncertainties for the brigade successfully applications, upgrades, and peer review. intervening in damage from the hot gas layer have been developed. Documentation for the selection of the 75% HRR as the only transient combustible fire load will have to be expanded once the suggested review is done of the program records and violations. The multi-compartment analysis which examines the risk across the physical analysis units which divide the plant is incomplete; therefore, documentation remains to be done. Information regarding FSS-B (Main Control Room Abandonment) was not available at the outset and had to be requested from the licensee.
SUPPORTING REQUIREMENTS FOR FIRE SCENARIO SELECTION AND ANALYSIS SR Level Observation Basis Cap Cat FSS- Suggestion Although hot work fires appear to be attributed F&O FSS-A1-1 Met A1 to most physical analysis units, it is not identified in the Unit 3 equipment room located in the FPRA Summary Report Task 16 Appendix A scenario description. Either provide a justification for excluding hot work from all zones where full fire damage is not assumed, i.e. non A zones, or add hot work scenario.
FSS- Suggestion Need to consider other equipment NUREG F&O FSS-A2-1 Met A2 6850 Appendix H Section H.2 with regards to scenarios involving solid state control components.
FSS- Summary From Section 6.1 of Oconee FPRA 031408 Met A3 Tasks 5 FPRA Model Development: Basic events linked to Appendix R components with known cable routing are assigned the Y1 disposition code. Basic events linked to components for which the cable location information will be determined are assigned the Y2 disposition code. Other fire affected components with unknown cable location information and linked directly to basic events are assigned the Y3 disposition code. Basic events assigned the Y3 disposition code are presumed failed unless specifically excluded for a given compartment or scenario. The credit by exclusion process is addressed in the Oconee FPRA 031408 Tasks 3, 9 and 10 Cable Selection Section 2.3 Credit By Exclusion (Y3 Components).
FSS- Summary The information from Oconee FPRA 031408 Met A4 Tasks 1 and 6 Partitioning and Frequency Attachment A, Fire Compartment Ignition Source Data Sheet and Oconee FPRA 031408 Tasks 1 and 6 Partitioning and Frequency Attachment B, Walkdown Sheets result in an Ignition Source/Scenario Development table which represents the fire sources and related target sets for each fire compartment. This table groups the scenario specific target sets so the fire compartment impact can be analyzed.
FSS- Finding Horizontal propagation outside zone of F&O FSS-A5-1 Not Met A5 influence (ZOI) not done yet, as the effects of PVC jacket (typically TP) on horizontal spread is an open item self identified by Oconee.
FSS- Suggestion Suggestion: Oconee has identified the need to F&O FSS-A5-2 A5 develop additional fire scenarios to evaluate the risk for the safe shutdown facility (SSF). These scenarios and their risk contribution should be reviewed.
FSS- Summary The approach used was to compare the 1&2
SUPPORTING REQUIREMENTS FOR FIRE SCENARIO SELECTION AND ANALYSIS SR Level Observation Basis Cap Cat A6 cumulative CCDP assuming the fire spread from left side of the main control board to the right with the cumulative CCDP assuming the fire spread from the right side of the main control board to the left. Once the damage distance between key targets was established, the probability of damage from NUREG/CR-6850 Appendix L was applied to the scenario.
FSS- Suggestion Lost degraded functions should be clearly F&O FSS-B1-1 Met B1 discussed in the documentation of the control room abandonment analysis.
FSS- Summary Two abandonment scenarios were postulated: 1&2 B2 Scenario W1 addresses Control Room abandonment resulting from a Main Control Board (MCB) fire; Scenario W2 addresses Control Room abandonment resulting from a fire originating from all other ignition sources (i.e., non Bin 4) in the Control Room. Each Control Room fire scenario may be divided into a severe and non-severe component. The non-severe cases are represented by the fire scenarios in Attachment A where Control Room abandonment is not postulated. The severe cases are assumed to lead to Control Room abandonment. The method used to calculate the CDF for Main Control Room Abandonment is given. Non Suppression Probability obtained from NUREG 6850 Figure P-2. Information regarding times and severity factors was obtained from the Hughes Associates Summary of Control Room Abandonment Times at the Oconee Nuclear Power Station Unit 3 Preliminary Results October 8, 2007.
FSS- Summary A two point model is applied for most ignition 2 C1 sources. An exception is made for transient fire sources, where the 75% heat release rate is used alone, and no higher HRR is applied. See FSS-D5 for a Finding on use of 75% HRR alone for transient combustibles FSS- Summary For criteria to establish HGL threshold, peak 1 C2 HRR assumed at t=0. For development of scenarios for individual ignition sources, the peak HRR assumed to occur initially as well.
FSS- Summary The choice to apply a peak heat release rate N/A C3 initially in the fire scenario is a conservative assumption.
No decay is applied for the HRRs due to a limitation of fuel; therefore no requirement is appropriate FSS- Suggestion Oconee should verify that hot work can F&O FSS-C4-1 2
SUPPORTING REQUIREMENTS FOR FIRE SCENARIO SELECTION AND ANALYSIS SR Level Observation Basis Cap Cat C4 reasonably be expected at most, if not all, locations in the physical analysis unit at an equivalent probability.
FSS- Finding For those cases with potentially pooling F&O FSS-C5-1 Not Met C5 thermoplastic, TP characteristics for failure should be attributed to Oconee cable.
FSS- Summary Thermoset target damage threshold applied, 1&2 C6 consistent with FSS-C5 FSS- Summary Fixed suppression system and manual N/A C7 suppression are not credited in the same scenario. Also, no credit is given for recovery of a failed fire suppression system.
FSS- Summary Oconee does not use cable/raceway fire wrap N/A C8 per plant personnel and the March 17, 2008 morning presentation. Could not find any reference to this in the Oconee FPRA 031408 document.
FSS- Summary Attachment B of Oconee FPRA 031408 Tasks 8 Met D1 and 11 Scenario Development is a summary of scoping fire modeling separation distance data for vertical and horizontal zone of influence.
Combustible packages considered in Attachment B are transient combustibles, combustible liquids, motor fires, pumps with lube oil and motors, battery, open electrical cabinets, high energy arcing faults, hydrogen fires, transformer fires, turbine generator fires.
Instruction is also given in this attachment on how to handle the effects on heat release rate based on the location of the combustible, i.e.,
against a wall or in a corner.
Hot gas layer criteria were developed from Hughes Associates Generic Fire Modeling Treatments January 5, 2007. The results of the hot gas layer evaluation are documented in the spreadsheet located in Oconee FPRA 031408 Tasks 8 and 11 Scenario Development Attachment C, Hot Gas Layer Compartment Evaluation.
FSS- Summary The Hughes Associates Generic Fire Modeling Met D2 Treatments January 5, 2007 gives details on the correlations and fire model that were used.
Many correlations were used to compare and contrast the output from various inputs. These outputs were also compared to the fire model CFAST. The fire model CFAST was the only zone model used in the calculations. Within the document there are lists of the assumptions that are used when using different correlations and CFAST. It appears that these correlations and
SUPPORTING REQUIREMENTS FOR FIRE SCENARIO SELECTION AND ANALYSIS SR Level Observation Basis Cap Cat model were used within their limitations.
FSS- Suggestion It is readily seen that the ability to model fires F&O FSS-D3-1 2 D3 near a wall or in a corner has been disabled in CFAST version 6.0.10, though this is not documented. This needs further investigation.
FSS- Summary The document Hughes Associates Generic Fire Met D4 Modeling Treatments January 5, 2007 provides the technical justification and assumptions used for the inputs to CFAST and correlations used.
FSS- Finding Finding: Oconee has provided a weak basis for F&O FSS-D5-1 1&2 D5 applying only the 75% fire HRR for transient combustibles, excluding the larger HRR.
FSS- Suggestion Provide a basis for those factors applied due to F&O FSS-D5-2 D5 the conditional trip probability.
FSS- Finding A probability should be developed for manual F&O FSS-D6-1 Met D6 suppression for the fire brigade intervening to prevent damage from the hot gas layer.
FSS- Summary Fixed suppression only credited for MFW pump. 2 D7 Those fixed suppression systems are maintained in accordance with applicable codes and standards; the credited system is in a fully operable state during plant operation except for expected, nominal unavailability; and the system has not experienced outlier behavior relative to system unavailability.
FSS- Summary Fixed suppression system only credited for Met D8 limiting fire damage for one U3 MFW pump scenario, i.e., the 100 gallon fire. Cable trays in close proximity on the East Wall are failed even with successful fixed suppression. The cables credited under successful fixed suppression are not in the immediate vicinity of the oil fire.
Critical cables are not credited for the larger 1000 gallon oil fire FSS- Summary Smoke damage to FPRA equipment was not 1 D9 considered. There is a no requirement listed for capability category one, therefore they automatically meet capability category one.
FSS- Summary Walkdowns were conducted to identify fire 2&3 D10 ignition sources and respective target sets within the ZOI according to the Hughes guidance. Information from those walkdowns were applied in Summary Fire Model Scoping Study sheets and the fire PRA scenarios FSS- Summary Walkdowns were performed to identify fire Met D11 hazards and fire protection systems and features. Information from those walkdowns was applied in Summary Fire Model Scoping Study sheets.
FSS- Summary The document Hughes Associates Generic Fire Met E1 Modeling Treatments January 5, 2007 gives
SUPPORTING REQUIREMENTS FOR FIRE SCENARIO SELECTION AND ANALYSIS SR Level Observation Basis Cap Cat references for the use of material properties used. Most information, data, and properties were derived from NUREG 6850.
FSS- Summary For fire modeling parameters generic Met E2 estimations were used from the referenced documents.
FSS- Summary The document Hughes Associates Generic Fire 1 E3 Modeling Treatments December 11, 2007 gives many examples of the uncertainties in the fire modeling and the effect of uncertainties on different parameters. Uncertainties in the material properties used in the fire modeling are also discussed. This is discussed in the terms of how the model is sensitive to different material properties such as the thermal conductivity or thermal diffusivity. An example is the gas layer temperature. It is very sensitive to the boundary materials. The sensitivity is such that the results could be substantially different if a different boundary material were assumed.
FSS- Summary Course assumptions regarding locations of Met E4 cables were made from applying the plant-specific exclusionary method for Y3 basic events.
FSS-F1 Summary The turbine building has exposed structural 1&2 steel. Scenarios are developed with high hazard sources within the turbine building with the potential for causing fire-induced failure of exposed structural steel. Sources outside the turbine building, i.e. yard transformers, are also considered for purposes of challenging the wall of the turbine building. Plant specific mitigating factors are discussed with respect to these scenarios affecting the turbine building Oconee provided additional information on structural collapse after the team initially indicated that all three of the SRs were not met.
All three of the SRs have been adjusted.
FSS-F2 Summary Capability category one has No Requirement 1 listed.
FSS-F3 Summary Oconee indicates that failure of a structural 1 steel member would not cause collapse of the turbine building. However, should it collapse, they state that a pre-existing quantified scenario based upon a MFW oil fire bounds the CCDP of failure of all components in the turbine building.
FSS- Finding Multi-compartment analysis does not include a F&O FSS-G1-1 Not Met G1 range of potential multi-compartment fire scenarios.
SUPPORTING REQUIREMENTS FOR FIRE SCENARIO SELECTION AND ANALYSIS SR Level Observation Basis Cap Cat FSS- Finding No screening criteria for multi-compartment F&O FSS-G2-1 Not Met G2 fires have been defined.
FSS- Finding The analysis has not screened potential multi- F&O FSS-G3-1 Not Met G3 compartment combinations of interest nor defined any multi-compartment fire scenarios beyond those that are inherently captured in the treatment of fire scenarios for the turbine building fire zones (see PP).
FSS- Finding Multi-compartment analysis is incomplete and F&O FSS-G4-1 Not Met G4 has not included an assessment of credits given to passive fire barrier features.
FSS- Finding Active fire barriers have been credited in F&O FSS-G5-1 Not Met G5 partitioning but not assessed per this SR.
FSS- Finding No assessment of a range of potential multi- F&O FSS-G6-1 Not Met G6 compartment scenarios has been provided.
FSS- Summary The fire scenarios identify the ignition source Met H1 and damage target set in each case, and are organized according to physical zones identified by Oconee. Should a severity factor and non-suppression probability be applied for a scenario, then its value is identified as well in the scenario. This information is organized well and facilitates fire PRA applications, upgrades, and peer review.
Some physical analysis units do not break down into fire scenarios per ignition source and these are captured as well in the same document.
FSS- Finding Treatment of PVC jacket on cable failure is not F&O FSS-H2-1 Not Met H2 addressed and is an open item. The cable jacket affects Oconee conclusion that TS failure criteria should be used. Oconee is collecting information regarding the PVC jacket to establish the nature of the PVC; however, PVC is typically thermoplastic material.
FSS- Summary The document Hughes Associates Generic Fire Met H3 Modeling Treatments December 11, 2007 provides the basis for selection of the applied fire modeling tools.
FSS- Summary The document Hughes Associates Generic Fire Met H4 Modeling Treatments December 11, 2007 documents the fire modeling input values used in the analysis of each fire scenario.
FSS- Summary The document Hughes Associates Generic Fire 3 H5 Modeling Treatments December 11, 2007 documents the results for each analyzed fire scenario including the results of parameter uncertainty. There is discussion within the document on the impact that uncertainties for certain input parameters in the context of the resulting fire risk estimates. Specifically the
SUPPORTING REQUIREMENTS FOR FIRE SCENARIO SELECTION AND ANALYSIS SR Level Observation Basis Cap Cat variations in output results related in the change in material properties used for inputs. For each model discussed there is usually a set of assumptions listed that are applied to that model.
FSS- Suggestion Expand documentation to explain area ratio F&O FSS-H6-1 1 H6 approach for hot work. Provide discussion that F&O FSS-D5-1 supports the contention that using the area ratio is adequate. Also provide expanded justification for plant specific modification to NUREG/CR-6850 for only considering 75%
HRR for transient combustibles, given plant records including violations of combustible controls.
FSS- Summary Refer to F&O FSS-D6-1. A specific example of F&O FSS-D6-1 Met H7 not meeting 20 minutes for a fire was given.
References were made to former cases as well.
FSS- Finding The multi-compartment analysis remains F&O FSS-H8-1 Not Met H8 incomplete (see FSS-F and its SRs); hence, documentation is also incomplete.
FSS- Finding There are no uncertainties listed for manual fire F&O FSS-H9-1 Met H9 brigade suppression which limits the development of the hot gas layer as given in the document Oconee FPRA 031408 Tasks 8 and 11 Scenario Development Attachment A, Scenario Summary Report.
FSS- Suggestion Suggestion: Document results of walkdowns to F&O Met H10 identify targets and raceways within ZOI FSS-H10-1 independently of fire PRA itself
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/17/2008 ID Number :FSS-A1-1 Level of Significance: Suggestion Reviewer: RXV Capability Category: Met OBSERVATION:
Fixed and transient ignition sources are identified in the following two documents:
- Oconee FPRA 031408 Tasks 1 and 6 Partitioning and Frequency Attachment A Fire Compartment Ignition Source Data Sheet.
- Oconee FPRA 031408 Tasks 1 and 6 Partitioning and Frequency Attachments B Walkdown Sheets.
- Approximately 3300 fixed ignition sources have been identified.
- Information from these two documents was used to develop the Ignition Source/Scenario Summary which is located in Oconee FPRA 031408 Tasks 8 and 11 Scenario Development Attachment A.
The transient walkdown was conducted to identify specific general transient locations where a trash bag fire could impact cable trays or risers. The hypothetical trash bag was generally assumed to be at floor level unless a ledge or permanent scaffolding obligated elevating the transient placement.
Suggestion: Hot work fires appear to be attributed to most physical analysis units. However, hot work is not identified in the Unit 3 equipment room located in the FPRA Summary Report Task 16 Appendix A scenario description, and no justification for excluding it is provided. Either provide a justification for excluding hot work from all zones where full fire damage is not assumed, i.e. non A zones, or add hot work scenario.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Oconee FPRA 031408 Tasks 8 and 11 Usama Farradj Scenario Development Attachment A
- 2. Oconee FPRA 031408 Tasks 1 and 6 Partitioning and Frequency Attachment A, Fire Compartment Ignition Source Data Sheet
- 3. Oconee FPRA 031408 Tasks 1 and 6 Partitioning and Frequency Attachment B, Walkdown Sheets
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/17/2008 ID Number :FSS-A2-1 Level of Significance: Suggestion Reviewer: RXV Capability Category: Met OBSERVATION:
Oconee FPRA 031408 Tasks 8 and 11 Scenario Development Attachment A identifies the targets (typically in terms of raceways and component failures) associated with each scenario.
From information obtained from the self assessment spreadsheet and discussion with personnel the damage criteria used was the thermoset cable damage criteria from NUREG/CR-6850.
BASIS FOR LEVEL OF SIGNIFICANCE:
Did not consider other equipment NUREG 6850 Appendix H Section H.2 with regards to scenarios involving solid state control components.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Oconee FPRA 031408 Tasks 8 and 11 Usama Farradj Scenario Development Attachment A
- 2. Self Assessment Information Spreadsheet
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :FSS-A5-1 Level of Significance: Finding Reviewer: JSH Capability Category: Not Met OBSERVATION:
Finding: Horizontal propagation outside zone of influence (ZOI) not done yet, as the effects of PVC jacket (typically TP) on horizontal spread is an open item self identified by Oconee. Current chemical composition of PVC jackets are being examined.
In most cases, Oconee establishes a zone of infuence ( ZOI) per ignition source and applies this ZOI to establish targets to develop those potentially risk significant contributors. The ZOI is established from the Hughes report. Should a target raceway be captured by the ZOI, then ZOI is extended to the ceiling.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Oconee FPRA 031408 Kiang Zee
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :FSS-A5-2 Level of Significance: Suggestion Reviewer: JSH Capability Category:
OBSERVATION:
Suggestion: Oconee has identified the need to develop additional fire scenarios to evaluate the risk for the safe shutdown facility (SSF). These scenarios and their risk contribution should be reviewed.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 2. Oconee FPRA 031408 Kiang Zee
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :FSS-B1-1 Level of Significance: Suggestion Reviewer: RXV Capability Category: Met OBSERVATION:
The abandonment criteria used in the document Hughes Associates Summary of Control Room Abandonment Times at the Oconee Nuclear Power Station Unit 3 Preliminary Results Revision 2 March 21, 2008 is as follows:
- Temperature 50 °C (122 °F)
- Smoke layer height 1.8 m (6 ft) above the floor
- Visibility criteria is based on an optical density of 3m-1 (0.9ft-1) which corresponds to a visibility of 0.4m (1.4ft) for a light reflecting surface and a visibility of 1.1m (3.7 ft) for a light emitting surface.
BASIS FOR LEVEL OF SIGNIFICANCE:
Lost degraded functions should be clearly discussed in the documentation of the control room abandonment analysis.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Oconee FPRA 031408 Tasks 8 and 11 Scenario Development
- 2. Hughes Associates Summary of Control Room Abandonment Times at the Oconee Nuclear Power Station Unit 3 Preliminary Results Revision 2 March 21, 2008
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :FSS-C4-1 Level of Significance: Suggestion Reviewer: JSH Capability Category: 2 OBSERVATION:
Severity factors are applied for ignition sources. In particular, for hot work, in addition to suppression credit, a factor is applied. Hot work is strategically placed in Oconee fire PRA according to a confluence of cables; therefore, the severity factor for hot work is developed according to probability of a particular location. Oconee should verify that hot work can reasonably be expected at most, if not all, locations in the physical analysis unit at an equivalent probability. Such an assumption, while common in the evaluation of transient combustibles, is used less often for hot work.
BASIS FOR LEVEL OF SIGNIFICANCE:
Two point fire intensity model is applied. The full split fraction from the two point approach is attributed to the fire frequency.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Oconee FPRA 031408 Usama Farradj
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :FSS-C5-1 Level of Significance: Finding Reviewer: JSH Capability Category: Not Met OBSERVATION:
Cable construction at Oconee is Armored with thermoset (TS) internal insulation, and PVC (typically thermoplastic (TP)) jacket. For those cases with potentially pooling thermoplastic, TP characteristics for failure should be attributed to Oconee cable. Note that NUREG/CR-6850, Appendix H section H.1.3, directs the analyst to use TP cable characteristics for cable construction such as Oconee's unless justification is provided. NUREG/CR-6850 provides guidance for selecting the overall treatment of such cable. This issue is an additional issue to the self identified one on PVC jacket for Oconee cables which was raised by Oconee with respect to horizontal propagation.
Oconee is getting further information on the jackets, and has identified the treatment of the jacket material as an open issue.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Oconee FPRA 031408 Usama Farradj Ed Simbles
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :FSS-D3-1 Level of Significance: Suggestion Reviewer: RXV Capability Category: 2 OBSERVATION:
The computer model CFAST version 6.0.1.0 was selected to compute the fire environment in generic enclosures because it provides a broader versatility than an empirical approach.
Because of the large number of parameters that are involved in a zone model analysis simplifying assumptions were necessary for practical application to generic enclosures. This is discussed in the Hughes Associates Generic Fire Modeling Treatments January 5, 2007 document. Areas have been identified that are risk significant in that a hot gas layer may develop in that area. No detailed fire modeling concerning a specific scenario, geometry, fuel loading, ventilation, etc., has been done with either CFAST or other fire models such as Fire Dynamics Simulator.
BASIS FOR LEVEL OF SIGNIFICANCE:
The following is from page 318 of the Hughes Associates Generic Fire Modeling Treatments January 5, 2007, It is readily seen that the ability to model fires near a wall or in a corner has been disabled in CFAST version 6.0.10, though this is not documented. This needs further investigation.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Hughes Associates Generic Fire Modeling Treatments December 11, 2007
- 2. Oconee FPRA 031408 Tasks 8 and 11 Scenario Development Attachment B, Summary Fire Modeling Scoping Study
- 3. Oconee FPRA 031408 Tasks 8 and 11 Scenario Development Attachment C, Hot Gas Layer Compartment Evaluation
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :FSS-D5-1 Level of Significance: Finding Reviewer: JSH Capability Category: 1&2 OBSERVATION:
Finding: Oconee has provided a weak basis for applying only the 75% fire HRR for transient combustibles, excluding the larger HRR. Oconee needs to review plant procedures, and administrative control records including violations, to provide adequate justification for their plant specific modification to a generic statistical model in NUREG/CR-6850.
BASIS FOR LEVEL OF SIGNIFICANCE:
Parsing of area according to location is acceptable for transient fires NUREG/CR-6850 Appendix L applied for Main Control Board fires Nominal credit for autosuppression (failures/demand) taken is in keeping with generally accepted credit Credit for manual suppression for hot work fires taken from NUREG/CR-6850 POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Oconee FPRA 031408
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :FSS-D5-2 Level of Significance: Suggestion Reviewer: JSH Capability Category: 1&2 OBSERVATION:
Suggestion: Provide a basis for the factors applied due to the conditional trip probability.
Sensitivity studies on this factor for a particular application; in particular for the 0.01 value, should be performed.
BASIS FOR LEVEL OF SIGNIFICANCE:
Parsing of area according to location is acceptable for transient fires NUREG/CR-6850 Appendix L applied for Main Control Board fires Nominal credit for autosuppression (failures/demand) taken is in keeping with generally accepted credit Credit for manual suppression for hot work fires taken from NUREG/CR-6850 POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Oconee FPRA 031408
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :FSS-D6-1 Level of Significance: Finding Reviewer: RXV Capability Category: Met OBSERVATION:
The document Hughes Associates Generic Fire Modeling Treatments January 5, 2007 provides the technical basis for the empirical models used.
BASIS FOR LEVEL OF SIGNIFICANCE:
Oconee has postulated that within 20 minutes of detection of a fire, the fire brigade can apply a hose stream to the fire and prevent additional damage to cables from the hot gas layer.
Discussion with Oconee personnel has indicated that this 20 minute time to apply a hose stream has typically been achieved. However, according to Oconee personnel, a response of 20 minutes to apply the hose stream has not been achieved for every drill. Time for the fire brigade to apply water to a fire depends upon several factors, including the location of the fire.
Therefore, a probability should be developed for preventing further damage from the hot gas layer.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Hughes Associates Generic Fire Modeling Usama Farradj Treatments December 11, 2007 Harold Lefkowitz
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :FSS-G1-1 Level of Significance: Finding Reviewer: SPN Capability Category: Not Met OBSERVATION:
Multi-compartment fire scenarios involving interactions between plant fire areas have been defined or analyzed. Examples include consideration of high hazard fire sources failing fire barriers (e.g. oil-filled transformers), failure of passive fire barriers (random or fire-induced),
failure of active fire barriers to operate on demand, etc.)
BASIS FOR LEVEL OF SIGNIFICANCE:
Analysis does not include a range of potential multi-compartment fire scenarios.
POSSIBLE RESOLUTION (REVIEWER):
Provide a systematic analysis of fire multi-compartment fire scenarios.
Reference(s): Personnel Contacted:
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :FSS-G2-1 Level of Significance: Finding Reviewer: SPN Capability Category: Not Met OBSERVATION:
No screening criteria for multi-compartment fires have been defined.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Define screening criteria Reference(s): Personnel Contacted:
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :FSS-G3-1 Level of Significance: Finding Reviewer: SPN Capability Category: Not Met OBSERVATION:
The anlaysis has not screened potential mult-compartment combinations of interest nor defined any multi-compartment fire scenarios beyond those that are inherently captured in the treament of fire scenarios for the turbine building fire zones (see PP).
BASIS FOR LEVEL OF SIGNIFICANCE:
SR has not been met.
POSSIBLE RESOLUTION (REVIEWER):
Conduct a complete multi-compartment fire analysis.
Reference(s): Personnel Contacted:
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :FSS-G4-1 Level of Significance: Finding Reviewer: SPN Capability Category: Not Met OBSERVATION:
multi-compartment analysis is incomplete and has not included an assessment of credits given to passive fire barrier features.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :FSS-G5-1 Level of Significance: Finding Reviewer: SPN Capability Category: Not Met OBSERVATION:
Active fire barriers have been credited in partitioning but not assessed per this SR.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :FSS-G6-1 Level of Significance: Finding Reviewer: SPN Capability Category: Not Met OBSERVATION:
No assessment of a range of potential multi-compartment scenarios has been provided.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 6 Date: 3/19/2008 ID Number :FSS-H2-1 Level of Significance: Finding Reviewer: JSH Capability Category: Not Met OBSERVATION:
Treatment of PVC jacket on cable failure is not addressed and is an open item. The cable jacket affects Oconee conclusion that TS failure criteria should be used. Oconee is collecting information regarding the PVC jacket to establish the nature of the PVC; however, PVC is typically thermoplastic material.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Oconee FPRA 031408 Usama Farradj
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 10 Date: 3/19/2008 ID Number :FSS-H6-1 Level of Significance: Suggestion Reviewer: JSH Capability Category: 1 OBSERVATION:
Expand documentation to explain severity factor approach for hot work. Provide discussion that supports the contention that using the area ratio is adequate.
Also provide expanded justification for plant specific modification to NUREG/CR-6850 for only considering 75% HRR for transient combustibles, given plant records including violations of combustible controls. See Finding on FSS-D5 for this assumption.
BASIS FOR LEVEL OF SIGNIFICANCE:
Documentation provided generally for severity factors.
MCB approach folllows NUREG/CR-6850.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Oconee FPRA 031408
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :FSS-H8-1 Level of Significance: Finding Reviewer: SPN Capability Category: Not Met OBSERVATION:
The multi-compartment analysis remains incomplete (see FSS-G and its SRs), hence, documentation is also incomplete.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Complete the multi-compartment analysis and document methos and results.
Reference(s): Personnel Contacted:
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :FSS-H9-1 Level of Significance: Finding Reviewer: RXV Capability Category: Met OBSERVATION:
The uncertainties regarding model use and assumptions are delineated in the Hughes Associates Generic Fire Modeling Treatments December 11, 2007 document. There is discussion regarding the uncertainties within the models and also the sensitivity the models have with input values such as material properties.
BASIS FOR LEVEL OF SIGNIFICANCE:
There are no uncertainties listed for manual fire brigade suppression which limits the development of the hot gas layer as given in the document Oconee FPRA 031408 Tasks 8 and 11 Scenario Development Attachment A, Scenario Summary Report. There is a deterministic criteria that is applied to limit the formation of a hot gas layer. There are no uncertainties documented associated with cable failure threshold all though the presence of PVC jackets complicates the failure threshold significantly.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Oconee FPRA 031408 FPRA Summary (Task 16)
- 2. Hughes Associates Generic Fire Modeling Treatments December 11, 2007
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 5 Date: 3/19/2008 ID Number :FSS-H10-1 Level of Significance: Suggestion Reviewer: JSH Capability Category: Met OBSERVATION:
Suggestion: Document results of walkdown independently of fire PRA itself.
BASIS FOR LEVEL OF SIGNIFICANCE:
Walkdown process applied for ZOI to identify targets and raceways within ZOI. Additional guidance to walkdown fire hazards and fire protection features. Results identified in PRA POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Oconee FPRA 031408 Ed Simbles
- 2. Hughes Assoc Generic Fire Modeling Usama Farradj Treatments 12/11/07
IGNITION FREQUENCY ELEMENT This element estimates the frequency of fires (expressed as fire ignitions per reactor-year). Fire frequencies are ultimately estimated for each selected fire scenario (from the FSS element) and can be developed for a compartment as a whole, for a group of ignition sources, or for a specific individual ignition source depending on the nature of the fire scenario. The ignition frequency values are fed forward to the FQ element for incorporation into the final risk calculations.
The following Note (3) from Table 4.5.1-2(c) of ASME RA-Sb-2005 under HLR-IE-C applies throughout HLR-IGN. Note that the IGN SRs for the Oconee FPRA were not evaluated against this Note because this Note was not followed in developing the generic ignition frequencies in NUREG/CR-6850, the currently acceptable source for generic ignition frequencies. It is anticipated that NUREG/CR-6850 will correct their frequencies (either through the NFPA-805 frequently asked question (FAQ) process or another revision) to align with the Note. Nonetheless, this Finding (applicable to all related SRs under HLR-IGN) is to ensure compatibility with the requirement of Note (3) to Table 4.5.1.2(c) of ASME RA-Sb-2005 (HLR-IE-C) throughout HLR-IGN for the Oconee FPRA.
Here is the Note. "For the computation of average annual CDF/LERF the appropriate units for initiating event frequency are events per calendar year, commonly expressed as events per reactor-year, where a reactor-year is one full calendar of experience for one reactor." Additional detail as to how to perform the appropriate calculation can be found in the Note.
HIGH LEVEL REQUIREMENTS FOR IGNITION FREQUENCY (IGN)
HLR HLR Description HLR Summary (From Review)
HLR-IGN-A The FPRA shall develop fire ignition frequencies for every Except for the Finding noted for IGN-A5 (endemic to NUREG/CR-physical analysis unit that has not been qualitatively 6850 ignition frequencies), this HLR is met throughout as Oconee screened. used the NUREG/CR-6850 values and techniques to assign ignition frequencies, including apportionment for transient fires. Plant-specific review and Bayesian update for Oconee fires through 2005 were performed. This HLR is well-documented, with only minor suggestions for quality assurance.
HLR-IGN-B The FPRA shall document the fire frequency estimation in As per HLR IGN-A, documentation for Ignition Frequency is very a manner that facilitates FPRA applications, upgrades, good, with only minor suggestions for quality assurance.
and peer review.
SUPPORTING REQUIREMENTS FOR IGNITION FREQUENCY SR Level Observation Basis Cap Cat IGN-A1 Summary This SR is Met because the NUREG/CR-6850 Met ignition frequency data are used and these are based on nuclear power history for plants of similar type, characteristics, etc. No datum was excluded. The NUREG/CR-6850 list of fire events between 1993 and 2000 was reviewed to confirm that important Oconee fire events were included.
IGN-A2 Summary This SR is N/A because no datum outside the N/A nuclear power industry was included.
IGN-A3 Summary This SR is N/A because no engineering N/A judgment was required or employed.
IGN-A4 Suggestion Sufficient time has passed since 2000, the last F&O IGN-A4-1 3 fire event date in the EPRI fire events database, so that an additional 5 years of Oconee experience may be used to Bayesian update the generic frequencies.
IGN-A5 Finding Need to update ignition frequency data once F&O IGN-A5-1 Met NUREG/CR-6850 is updated with the correct numbers based on reactor-year basis.
IGN-A6 Summary This SR is Met because plant-specific Bayesian Met updating was performed in order to determine if any generic frequencies from NUREG/CR-6850 should be adjusted. Only two events met the criteria for inclusion and Bayesian update, and one of those events was already in the EPRI database (pre-2001) and, therefore, not used to Bayesian update the generic priors. The other event affects Bin 21, Pumps. Starting with the NUREG/CR-6850 ignition frequency for Bin 21 (2.1E-02/ry), and considering one additional event in 13.27 additional reactor years, the updated frequency is 3.10E-02/ry. Bayesian update spreadsheet BayesSRL.v01_1.xls was used for the update.
IGN-A7 Summary This SR is Met because the NUREG/CR-6850 Met ignition source counting and frequency apportioning methods are used, as supplemented by NFPA-805 FAQs.
For Transient Cable Fires Caused by Cutting and Welding (Bins 5, 11, and 31), the NUREG/CR-6850 guidance suggests using the ratio of quantity of cables in compartment to the total quantity in the location as one of the weighting factors. In lieu of actual cable loading data (unavailable at Oconee), this weighting factor was based on the number of ARTRAK raceways in the compartment. It is noted that
SUPPORTING REQUIREMENTS FOR IGNITION FREQUENCY SR Level Observation Basis Cap Cat ARTRAK data typically includes "credited" trays as well as endpoints which can lead to variations with actual cable loading (conservative by including endpoints and non-conservative by ignoring non-credited trays). Additionally, the Unit 3 data includes routing points while routing points are not generally applicable to the Unit 2 data (and the Unit 1 data which is incomplete).
Consequently, the values for some compartments were adjusted to account for these variations. However, the primary objective in using raceway data was to provide a means to reflect a higher cable fire transient frequency for compartments with an expectedly higher density of cables.
As per the Discussion, a calculation was performed by Oconee staff to verify that the sums of ignition bin frequencies [ISDS] and physical analysis unit frequencies [Section 10]
match (i.e., "plant-wide fire frequency must be conserved"). This calculation was provided via Excel spreadsheet "OC Fire Ignition Frequency Workbook - 805 Version N.xls."
IGN-A8 Summary This SR is CC-III because not only are greater- 3 than-zero ignition frequencies assigned to every plant physical analysis unit, but also each potentially fire-risk-relevant ignition source has an assigned frequency.
IGN-A9 Suggestion Recalculate ignition frequencies for transient F&O IGN-A9-1 Met activities in physical analysis units based on reassignment of values for LDST Rooms.
IGN- Summary This SR is CC-III because (1) use of the 3 A10 NUREG/CR-6850 fire ignition frequencies carries with it fully characterized uncertainty distributions; and (2) the Bin-21 frequency resulting from plant-specific Bayesian update also has a fully characterized uncertainty distribution analogous to those for the NUREG/CR-6850 ignition frequencies.
IGN-B1 Summary This SR is Met per the documentation in OSC- Met 8979.
IGN-B2 Summary This SR is Met per the documentation in OSC- Met 8979.
IGN-B3 Summary This SR is Met per the documentation in OSC- Met 8979.
IGN-B4 Summary This SR is Met per the documentation in OSC- Met 8979.
IGN-B5 Suggestion In OSC-8979, include reference to (or include F&O IGN-B5-1 Met specifically) the discussion of ignition frequency uncertainties in NUREG/CR-6850, including parametric values for the generic frequencies.
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/6/2008 ID Number :IGN-A4-1 Level of Significance: Suggestion Reviewer: RHG Capability Category: 3 OBSERVATION:
Oconee plant fire experience has been collected for all dates since the plant began commercial operation. The events were reviewed to see if they met the criteria for challenging fire events as defined in NUREG/CR-6850, Appendix C. When an event was considered challenging, it was assigned to one of the 37 frequency bins depending on location and ignition source. The event(s) in these bins were then used to Bayesian update the generic fire ignition frequencies provided in Table C-3 of NUREG/CR-6850, Appendix C. Sufficient time has passed since 2000, the last fire event date in the EPRI fire events database, so that an additional 5 years of Oconee experience may be used to Bayesian update the generic frequencies. These subsequent years were collected and reviewed in order to determine if they meet NUREG/CR-6850 criteria for "challenging." To be considered a challenging fire event any one of the following must be true about the event: (1) A hose stream, multiple portable fire extinguishers, and/or a fixed fire suppression system (either manually or automatically actuated) were used to suppress the fire; (2) One or more components outside the boundaries of the fire ignition source were affected where the term "outside the boundaries of the fire ignition source" will depend on the specific ignition source; (3) Combustible materials outside the boundaries of the fire ignition source were ignited "outside the fire ignition source;" Or (4), the event must meet any 2 of the following criteria: (a) Actuation of an automatic detection system; (b) A plant trip was experienced; (c) A reported loss of greater than $5,000 (not including any lost business damages); or (d) A burning duration or suppression time of 10 minutes or longer. The Fire Protection Engineering Support Document was used in addition to a Problem Investigation report (PIP) search for the review of fire events between 2001 and 2005. The criteria for the PIP search was that the brief problem description contained the character strings, "smo," "fire," "flash," or "arc." The fire events associated with these searches, deemed relevant to this analysis, were listed and dispositioned.
In addition to the Objective Criteria cited by Oconee in its review of plant-specific fire events for potential inclusion through Bayesian update, NUREG/CR-6850 also specifies Subjective Criteria to be considered. As stated there, "[a] fire was classified as potentially challenging if there are sufficient indications to determine that the fire was self-sustaining or that it might have affected components or led to ignition materials outside the fire ignition source.
This judgment may be based on the general tone of the event report or on the observation of specific aspects of a fire event. In general, observations of the following features in an event report can be indicative of a potentially challenging fire: (1) It is apparent that active intervention was needed to prevent potential spread; (2) There are indications that heat was generated of sufficient intensity and duration to affect components outside the fire ignition source, had such been in close proximity to the ignition source; (3) There are indications that flames or heat were generated of sufficient intensity and duration to cause the ignition of secondary combustibles outside the fire ignition source, had such been in close proximity to the ignition source; (4)
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/6/2008 ID Number :IGN-A4-1 Level of Significance: Suggestion Reviewer: RHG Capability Category: 3 Substantial smoke was generated (e.g., a room was reported to be smoke-filled when first responders arrived on the scene, or the report includes a description (such as 'heavy' or 'dense smoke)." These Subjective Criteria need to be considered for the Oconee plant-specific fires from 2001 onward to determine if there might be others that merit inclusion for the Bayesian update.
BASIS FOR LEVEL OF SIGNIFICANCE:
While it is recognized that events prior to 2001 were assumed to already have been included in the NUREG/CR-6850 fire events database, still consider re-evaluating the following plant-specific fire event in terms of whether or not it should be treated as "challenging" based on the cited criteria. It is #35 (year 2000) in Table C-2. The lack of available information as to the fire progression and means of suppression brings into question its exclusion as "challenging," at least without further discussion as to why it was excluded. "O-00-01925: During CRD Patch testing an arc and fireball was observed. No information on how the fire was extinguished, but it is noted that the fuses blew in the unit. Damage was noted on the breaker and other related components in the same panel."
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. OSC-8979
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/6/2008 ID Number :IGN-A5-1 Level of Significance: Finding Reviewer: RHG Capability Category: Met OBSERVATION:
This SR is Met because the NUREG/CR-6850 ignition frequency data are used and these are calculated on a reactor-year basis which includes weighting by the plant availabilities in the database. In addition, plant-specific Bayesian updating was performed in order to determine if any generic frequencies from NUREG/CR-6850 should be adjusted. Only two events met the criteria for inclusion and Bayesian update, and one of those events was already in the EPRI database (pre-2001) and, therefore, not used to Bayesian update the generic priors. The other event affects Bin 21, Pumps. Starting with the NUREG/CR-6850 ignition frequency for Bin 21 (2.1E-02/ry), and considering one additional event in 13.27 additional reactor years, the updated frequency is 3.10E-02/ry. Bayesian update spreadsheet BayesSRL.v01_1.xls was used for the update.
BASIS FOR LEVEL OF SIGNIFICANCE:
The following Note (3) from Table 4.5.1-2(c) of ASME RA-Sb-2005 under HLR-IE-C applies throughout HLR-IGN. Note that the IGN SRs for the Oconee FPRA were not evaluated against this Note because this Note was not followed in developing the generic ignition frequencies in NUREG/CR-6850, the curently acceptable source for generic ignition frequencies. It is anticipated that NUREG/CR-6850 will correct their frequencies (either through the NFPA-805 FAQ process or another revision) to align with the Note. Nonetheless, this Finding (applicable to all related SRs under HLR-IGN) is to ensure compatibility with the requirement of Note (3) to Table 4.5.1.2(c) of ASME RA-Sb-2005 (HLR-IE-C) throughout HLR-IGN for the Oconee FPRA.
Here is the Note. "For the computation of average annual CDF/LERF the appropriate units for initiating event frequency are events per calendar year, commonly expressed as events per reactor-year, where a reactor-year is one full calendar of experience for one reactor." Additional detail as to how to perform the appropriate calculation can be found in the Note.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. OSC-8979
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/6/2008 ID Number :IGN-A9-1 Level of Significance: Suggestion Reviewer: RHG Capability Category: Met OBSERVATION:
This SR is Met, as all physical analysis units have been assigned frequencies for transient combustible fires. Oconee staff was questioned about the assignment of a zero to the Maintenance Weighting Factor for Transient Fire. Such an assignment presumes that transient combustible fires are precluded by design during power operations. This translates into assigning a zero fire frequency for Transients due to Welding and Cutting and Cable Fires due to Welding and Cutting for the corresponding physical analysis unit. There were four such zero assignments, the LDST Rooms in each unit and the Unit 1 Lube Oil Storage House. Upon questioning, the Oconee staff determined that a zero assignment was appropriate only for the Unit 1 Lube Oil Storage House, because that location is strictly for storage (no maintenance activities conceivable). For the other three LDST Rooms, the Maintenance Weighting Factor was raised to 1 (Low) based on these Rooms being very high radiation zones (locked with highly restricted entry).
BASIS FOR LEVEL OF SIGNIFICANCE:
Recalculate ignition frequencies for transient activities in physical analysis units based on reassignment of values for LDST Rooms.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. OSC-8979 Brandi Weaver Harold Lefkowitz Charles Williams
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/6/2008 ID Number :IGN-B5-1 Level of Significance: Suggestion Reviewer: RHG Capability Category: Met OBSERVATION:
This SR is Met because the uncertainties associated with the NUREG/CR-6850 ignition frequency data automatically apply (although this should be mentioned specifically in OSC-8979) - as per R0237-05-0001.6, Rev. D, "[i]n general, the sources of uncertainty for each of the FPRA development tasks are discussed in the industry reference document, EPRI TR-1011989/NUREG-6850." R0237-05-0001.6, Rev. D, discusses uncertainty for counting ignition sources in a general sense, along with specific discussion of uncertainty inherent to the Bayesian update process.
BASIS FOR LEVEL OF SIGNIFICANCE:
In OSC-8979, include reference to (or include specifically) the discussion of ignition frequency uncertanties in NUREG/CR-6850, including parametric values for the generic frequencies.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. OSC-8979
- 2. R0237-05-0001.6, Rev. D
QUANTITATIVE SCREENING ELEMENT This element involves the screening of fire compartments based on their quantitative contribution to fire risk. [As with QLS, element QNS only considers physical analysis units as individual risk contributors. All physical analysis units are reconsidered as a part of the multi-compartment fire scenario analysis (see HLR-FSS-E).] Physical analysis units (PAUs) whose contribution to fire risk is shown to meet the quantitative screening criteria need not be analyzed in additional detail.
HIGH LEVEL REQUIREMENTS FOR QUANTITATIVE SCREENING (QNS)
HLR HLR Description HLR Summary (From Review)
HLR-QNS-A If quantitative screening is performed, the FPRA shall Quantitative screening developed at the PAU (building structure establish quantitative screening criteria to ensure the PAUs only) level, and ignition sources within PAUs. Impact of 4 estimated cumulative impact of screened physical analysis screened buildings not evaluated but most likely very low. Impact units on CDF and LERF is small. of screened ignition sources retained in final risk estimates as ignition frequency times plant trip CCDP/CLERP HLR-QNS-B If quantitative screening is performed, the FPRA shall identify those physical analysis units that screen out as individual risk contributors.
HLR-QNS-C VERIFY the cumulative impact of screened physical Not done but unimportant at building level, no evaluation of analysis units on CDF and LERF is small. magnitude of contribution at ignition source level but also most likely unimportant.
HLR-QNS-D The FPRA shall document the results of quantitative Building screening documentation incomplete, ignition source screening in a manner that facilitates FPRA applications, screening well documented.
upgrades, and peer review
SUPPORTING REQUIREMENTS FOR QUANTITATIVE SCREENING SR Level Observation Basis Cap Cat QNS- Summary During the building structure screening Met A1 defined the criteria that overall fire frequency in a building structure that is less than 10X lower than internal events initiating frequency assuming same level of fire damage could be screened out. Physical analysis units (PAUs) and fire ignition sources within PAUs with a
<10E-7 CDF were not further evaluated by an ignition source analysis but conservative CDF (assuming all possible targets failed) included in final results.
QNS- Summary Unclear if quantitative screening applied to Met B1 buildings structures defined in OSC-8979 (see QNS-A1) was ever applied, although the final screening of 4 non-qualitative screened structures is unknown.
QNS- Summary The PAUs that were screened from ignition Met B2 source analysis were retained and identified for consideration during the multi-compartment scenarios. This is important because PAUs are not separated by walls and a fire in one PAU might easily fail a component in another PAU - this would not be found unless an ignition specific analysis was done. The screened PAUs are carried over to the multi-compartment analysis.
QNS- Summary Quantitative screening criteria (buildings 1 C1 structures) were defined based on less than 10% of internal event initiating event frequency for same damage event. So high risk areas most likely not screened out but no evaluation to demonstrate satisfying Cat II or III was met because there was no evaluation relating criteria on initiating event frequency to risk significance QNS- Summary Disposition of 4 building structure PAUs left Met D1 open, possibly based on quantitative screening. Maintenance Support Bldg, Service Bldg, Admin Bldg, and cluster of building north east of plant identified for further analysis but no further analysis identified. See F&O QLS-A3-1.
QNS- Table provided of buildings structures PAUs Met D2 screened out and reason (aside from 4 not finally dispositioned in QNS-D1). Each fire PAU has one or more table entries. From these table entries it can be determined if the PAU was quantified as one unit, or if it was broken up into ignition sources.
CIRCUIT FAILURES ELEMENT This element refines that treatment of fire-induced cable failures and their impact on the plant equipment, systems, and functions included in the FPRA plant response model. This element also estimates the relative likelihood of various circuit failure modes such as loss of function failures versus spurious operation failures. Quantified circuit failure mode likelihood estimates are incorporated into the FPRA plant response model (developed under element PRM) as a part of CCDP and CLERP quantification in element FQ.
HIGH LEVEL REQUIREMENTS FOR CIRCUIT FAILURES (CF)
HLR HLR Description HLR Summary (From Review)
HLR-CF-A The FPRA shall determine the applicable conditional Based upon conversations with licensee staff, both supporting probability of the cable and circuit failure mode(s) that requirements for this HLR were met. However, the performance of would cause equipment functional failure and/or undesired these tasks was not documented. Two suggestions were made spurious operation based on the credited function of the regarding documentation. Refer to F&O suggestions CF-A1-1 and equipment in the FPRA. CF-A2-1.
HLR-CF-B The FPRA shall document the development of the The supporting requirement for this HLR was not met due to lack of elements above in a manner that facilitates FPRA documentation of the tasks performed. Refer to F&O finding CF-applications, upgrades, and peer review. B1-1.
SUPPORTING REQUIREMENTS FOR CIRCUIT FAILURES SR Level Observation Basis Cap Cat CF-A1 Suggestion Basic event GHP014BDEX, which appears in F&O CF-A1-1 2&3 the cutsets for AB089Y7 (0.3), should be added to the altered events list by Oconee staff, if appropriate. Oconee staff should add discussion to the altered events table for the three basic events cited by Note 5 as candidates for "further circuit analysis" (FEF0038MVT, FEF0047MVT, and HHP0031AVT), but for which failure probabilities of 1.0 were actually assigned.
CF-A2 Suggestion Include the uncertainty values from NUREG/CR- F&O CF-A2-1 Met 6850 directly into the documentation.
CF-B1 Suggestion Consider adding the additional discussion in SR F&O CF-B1-1 Met A2 to the documentation.
FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/13/2008 ID Number :CF-A1-1 Level of Significance: Suggestion Reviewer: RHG Capability Category: 2&3 OBSERVATION:
This SR is CC II/III. Following cable selection is circuit failure analysis, with specific attention paid to spurious actuations for fire both inside and outside containment. While intercable hot shorting is deemed too unlikely to include in modeling due to the exclusive use of armored cables (except for circuitry in the Main Control Board, which is not armored), best estimates and upper bounds from NUREG/CR-6850 are assigned for intracable spurious actuations as follows:
(1) 0.3 is used for all M/C intracable hot shorts based on the best estimate for circuits protected by a CPT (NUREG/CR-6850 Table 10-1) or the upper bound for an armored cable without a CPT (Table 10-5); (2) 0.6 is used for M/C intracable hot shorts in the MCB based on the best estimate for thermoset cable without a CPT (Table 10-2) [note that this would bound any non-armored intercable hot shorts within the MCB as well]. In addition, to ensure that the assigned 0.3 values were appropriate when reliance on instrumentation signals in open or closed circuitry, a table of "altered events" (basic events assigned fire-induced spurious actuation probabilities) was created and its entries' schematics reviewed for such reliance based on a set of criteria. Basic event GHP014BDEX, which appears in the cutsets for AB089Y7 (0.3), will be added to the altered events list by Oconee staff, if appropriate.
Oconee staff will add discussion to the altered events table for the three basic events cited by Note 5 as candidates for "further circuit analysis" (FEF0038MVT, FEF0047MVT, and HHP0031AVT), but for which failure probabilities of 1.0 were actually assigned.
BASIS FOR LEVEL OF SIGNIFICANCE:
Basic event GHP014BDEX, which appears in the cutsets for AB089Y7 (0.3), should be added to the altered events list by Oconee staff, if appropriate. Oconee staff should add discussion to the altered events table for the three basic events cited by Note 5 as candidates for "further circuit analysis" (FEF0038MVT, FEF0047MVT, and HHP0031AVT), but for which failure probabilities of 1.0 were actually assigned. Oconee staff verified that the use of the conservative probability
= 1.0 did not impact the CDF results for the dominant screening scenarios (i.e., even if lower probabilities were assigned, the CDFs did not change due to other failures in the cutsets)
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. R0237-05-0001.3, Rev. E Ed Simbles
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/13/2008 ID Number :CF-A2-1 Level of Significance: Suggestion Reviewer: RHG Capability Category: Met OBSERVATION:
This SR is Met. By using the values from NUREG/CR-6850, the associated uncertainties are assumed to apply (see Tables 10-1 through 10-5).
BASIS FOR LEVEL OF SIGNIFICANCE:
Include these uncertainty values directly into the documentation.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. R0237-05-0001.3, Rev. E
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/13/2008 ID Number :CF-B1-1 Level of Significance: Suggestion Reviewer: RHG Capability Category: Met OBSERVATION:
This SR is Met because the material discussed in SRs CF-A1 and A2 has been incorporated into the documentation.
BASIS FOR LEVEL OF SIGNIFICANCE:
Consider adding the additional discussion in SR A2 to the documentation.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. R0237-05-0001.3, Rev. E
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HUMAN RELIABILITY ANALYSIS ELEMENT This element considers operator actions as called out in the relevant plant fire response procedures. It also includes the identification of human failure events (HFEs) for inclusion in the FPRA plant response model. The HRA element also includes the quantification of human error probabilities (HEPs) for the modeled actions which are fed forward to element FQ in support of the CCDP and CLERP calculations for each selected fire scenario from element FSS.
HIGH LEVEL REQUIREMENTS FOR HUMAN RELIABILITY ANALYSIS (HRA)
HLR HLR Description HLR Summary (From Review)
HLR-HRA-A The FPRA shall identify human actions Even though the reviewer concluded that this high level requirement has been met, relevant to the sequences in the FPRA there is no documentation to support this.
plant response model.
HLR-HRA-B The FPRA shall include events where No new human failure events (HFEs) were defined for the 2008 fire PRA model but appropriate in the FPRA that represent a limited number of HFEs were carried over from the 2005 fire PRA. The definition the impacts of incorrect human responses of these HFEs is inadequate.
associated with the identified human actions.
HLR-HRA-C The FPRA shall quantify HEPs associated A process was defined for adjusting the human error probabilities (HEPs) to with the incorrect responses accounting account for the effects of fires, but the assumptions underlying it were not for the plant-specific and scenario-specific documented. A review of the implementation of the process indicated an instance influences on human performance, of misinterpretation of the definition of an HFE with respect to its timing in the particularly including the effects of fires. context of the accident scenario. The HRA should be reviewed to confirm that the HFEs are understood and quantified correctly in the context of the accident scenarios.
HLR-HRA-D The FPRA shall include recovery actions Few recovery events are identified, and they are evaluated according to the only if it has been demonstrated that the screening rules.
action is plausible and feasible for those scenarios to which it applies, particularly accounting for the effects of fires.
HLR-HRA-E The FPRA shall document the HRA, The documentation of the HRA is inadequate. Specifically: there is no description including the unique fire-related influences of the way in which the procedures are followed given a fire, which is necessary to of the analysis, in a manner that facilitates draw the conclusion that the HFEs modeled in the internal events PRA are still valid FPRA applications, upgrades, and peer for the fire PRA; the assumptions supporting the HEP adjustment to reflect the fire review. performance shaping factors (PSFs) are not documented; and the documentation of the evaluation of the HEPs for the 2005 fire PRA HFEs is incomplete.
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SUPPORTING REQUIREMENTS FOR HUMAN RELIABILITY ANALYSIS SR Level Observation Basis Cap Cat HRA-A1 Finding No documentation that for each fire scenario, for F&O HRA-A1-1 Met each safe shutdown action carried over from the Internal Events PRA, each action remains valid in the context of the Fire PRA HRA-A1 (internal events SR referenced by HRA-A1 and Met HR-E1 HRA-A2) See comment on HRA-A1.
HRA-A1 (internal events SR referenced by HRA-A1 and Met HR-E2 HRA-A2) The actions that are analyzed fall into both categories in the requirement.
HRA-A1 (internal events SR referenced by HRA-A1 and Met HR-E3 HRA-A2) Since no new actions were identified, the category associated with this SR is the same as for the internal events.
HRA-A1 (internal events SR referenced by HRA-A1 and 1 HR-E4 HRA-A2) No evidence of any simulator observations or talk-throughs.
HRA-A2 Summary There are no fire-specific safe shutdown actions Met included in the model (Ed Simbles). There are no Appendix R manual actions, except for those taken to remove power from those minor lines associated with the main steam lines after they have been closed, to prevent them reopening if there were spurious actuation (Camden Eflin).
However, on further review there are a number of fire-scenario specific HFEs, CASWHPIDHE and CEF0ASWDHE, that were included in Rev 3 of the fire PRA model that were incorporated into the current fire PRA model.
HRA-B1 Suggestion No new HFEs were added nor were existing F&O HRA-B1-1 N/A HFEs modified. However, HR-F2 requires the definition of the HFEs to include accident sequence specific timing of cues. This needs to be verified to conclude that the HFE definitions are still valid.
HRA-B1 (internal events SR referenced by HRA-B1, N/A HR-F1 HRA-B2 and HRA-B3) The events CASWHPIDHE and CEF0ASWDHEare defined appropriately in terms of impact HRA-B1 Summary (internal events SR referenced by HRA-B1, Met HR-F2 HRA-B2 and HRA-B3) See comment on HRA-B1.
HRA-B2 Finding For events CASWHPIDHE and CEF0ASWDHE F&O HRA-B2-1 Not Met the definition of the HFEs is not as detailed as that for the other HFEs.
Rob Boyer (Duke Energy Carolinas, LLC) agreed and indicated that this documentation would be improved.
HRA-B3 Summary None identified. N/A
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SUPPORTING REQUIREMENTS FOR HUMAN RELIABILITY ANALYSIS SR Level Observation Basis Cap Cat HRA-C1 Finding The approach to the quantification of the HEPs F&O HRA-C1-1 Not Met is to revise the internal events HEPs using a set of rules revising the HEPs based on, among other things, allowable action time. The basis, or the set of assumptions upon which this set of rules is based is not provided. This does not seem to have been applied correctly.
See also HRA-C1-HR-G4 through 7.
HRA-C1 (internal events SR referenced by HRA-C1) 1 HR-G1 Screening values have been used for all HEPs, HRA-C1- (internal events SR referenced by HRA-C1) The Met HR-G2 screening values are based on the existing HEPs, the method for which, in principle, includes failure in cognition as well as execution.
HRA-C1 Suggestion (internal events SR referenced by HRA-C1) The F&O HR-G3-1 Met HR-G3 approach used for the cognitive contribution is to use either the CBDT method or the original HCR method. The latter has been superseded by the EPRI ORE/HCR method, since the basis for the original HCR was unsupported by the ORE project back in the late 1980s. Recommend changing from the HCR to a newer methodology (e.g., the HCR/ORE) in the revision 4 update of the PRA.
HRA-C1 (internal events SR referenced by HRA-C1) For F&O HRA-C1-1 Not Met HR-G4 events CASWHPIDHE and CEF0ASWDHE the basis for the time available is not provided HRA-C1 (internal events SR referenced by HRA-C1) For F&O HRA-C1-1 Not Met HR-G5 events CASWHPIDHE and CEF0ASWDHE the basis for the timing is not provided.
HRA-C1 Finding (internal events SR referenced by HRA-C1) F&O HRA-C1-2 Not Met HR-G6 There is no evidence that the fire related post-initiator HEP quantifications have been checked for consistency.
HRA-C1- Finding In reviewing the documentation for ZHFC-2-058 F&O HR-G7-1 Not Met HR-G7 there is evidence that there is a lack of appreciation of the relative timing of events. The comment in the documentation on relative timing focuses on cognitive response time (2 minutes and 15 minutes for the two events (NSF0RCMDHE and CASWHPIDHE) respectively. However, these two events are separated in time by a significant time, the first event being required at 30 minutes, the second at four hours respectively.
Finding: The dependency evaluations should be reviewed carefully for the internal events model and the fire model.
HRA-C1 (internal events SR referenced by HRA-C1) Met Met
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SUPPORTING REQUIREMENTS FOR HUMAN RELIABILITY ANALYSIS SR Level Observation Basis Cap Cat HR-G9 to the extent that it is met in the internal events.
HRA-D1 Summary Relatively few recovery events are included and Met are evaluated according to the screening rules.
HRA-E1 Finding There is no documentation to describe the F&O HRA-E1-1 Not Met procedures and their use during a fire scenario.
There is no documentation of the assumptions underlying the screening approach. There is no justification that the timing associated with the analyzed HFEs is appropriate for the accident scenarios.
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :HRA-B1-1 Level of Significance: Suggestion Reviewer: GWP Capability Category: N/A OBSERVATION:
With the exception of the events identified in the Rev 3 fire PRA (OSC-8789) no new events are included and no modifications of the HFE definitions made. However, HR-F2 requires the definition of the HFEs to include accident sequence specific timing of cues for both capability category I and II. The report does not specify whether, and if so, how, this was achieved. The philosophy of the internal events model (Kiang Zee) is that the HFEs are included on a generic basis with the most demanding boundary conditions so that the model is, if anything, conservative. This is a widely used practice, and this is more of a general methodological issue than an issue specifically related to the fire PRA model. In terms of the fire model, the reviewer was recommended to review the expert panel considerations concerning unique fire induced core damage sequences (section 7.4 of OSC-8978). This however refers to what the panel will do, not what its conclusions were. The MSO expert panel meeting minutes reviewed did not contain any conclusions.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
While no specific accident scenarios were identified during the review that raised this as a significant concern, it is recommended that the timing be verified to conclude that the HFE definitions are still valid.
Reference(s): Personnel Contacted:
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :HRA-B2-1 Level of Significance: Finding Reviewer: GWP Capability Category: Not Met OBSERVATION:
The definition of the HFEs CASWHPIDHE and CEF0ASWDHE is not as detailed as that for the other HFEs incorporated from the internal events PRA, particularly with respect to timing issues.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Refine the definitions to the same level of detail as those in the internal events HRA analysis.
Reference(s): Personnel Contacted:
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :HRA-C1-1 Level of Significance: Finding Reviewer: GWP Capability Category: Not Met OBSERVATION:
The approach to the quantification of the HEPs is to revise the internal events HEPs using a set of rules revising the HEPs based on, among other things, allowable action time.
The basis, or the set of assumptions upon which this set of rules is based is not provided, but on discussion with Kiang Zee it is based on the assumption that, after a certain time, the fire is under control and there is no impact on the HEP from additional stress. Document the assumptions behind the screening analysis.
However, this does not seem to have been applied correctly. For example for event HHPHPR0DHE, switchover to recirculation, the allowable time is given as 3.5 minutes. This is in fact the time available from when the cue (low level in the RWST) to perform the switchover is reached. This cue however, occurs after a long time, much longer than the 30 minutes used as the criterion for changing the HEP, since the RWST must be depleted for this to happen. The HEPs need to be reviewed for when they actually occur in the time line of the accident.
For events CASWHPIDHE and CEF0ASWDHE the basis for the time available is not provided.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Document the assumptions for the revision of the HEPs from the internal events analysis.
Review to make sure that the rules have been applied correctly.
Reference(s): Personnel Contacted:
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number : HR-G3-1 Level of Significance: Suggestion Reviewer: GWP Capability Category:
OBSERVATION:
Internal events SR HR-G3-2 is incorporated by reference. The category is the same as for the internal events for the base value before modification.
The approach used for the cognitive contribution is to use either the CBDT method or the original HCR method. The latter has been superceded by the EPRI ORE/HCR method, since the basis for the original HCR was unsupported by the ORE project back in the late 1980s.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Rob Boyer (Duke Energy Carolinas, LLC) indicated that there is a plan to switch from the HCR to the HCR/ORE in the revision 4 update of the PRA.
Reference(s): Personnel Contacted:
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number : HRA-C1-2 Level of Significance: Finding Reviewer: GWP Capability Category: Not Met OBSERVATION:
(internal events SR referenced by HRA-C1) There is no evidence that the fire related, post-initiator HEP quantifications have been checked for consistency BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number : HR-G7-1 Level of Significance: Finding Reviewer: GWP Capability Category: Not Met OBSERVATION:
In reviewing the documentation for ZHFC-2-058 there is evidence that there is a lack of appreciation of the relative timing of events. The comment in the dcoumentation on relative timing focuses on cognitive response time (2 minutes and 15 mintes for the two events (NSF0RCMDHE and CASWHPIDHE) respectively. However, these two events are separated in time by a significant time, the first event being required at 30 minutes, the second at four hours repectively.
Finding: The dependency evaluations should be reviewed carefully for the internal events model and the fire model.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/17/2008 ID Number :HRA-E1-1 Level of Significance: Finding Reviewer: GWP Capability Category: Not Met OBSERVATION:
There is no documentation to describe the procedures and their use during a fire scenario. This is needed to justify the same HFEs that are included in the internal events model are relevant for the fire PRA PRM.
There is no documentation of the assumptions underlying the screening approach.
There is no justification that the timing associated with the analyzed HFEs is appropriate for the accident scenarios.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
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SEISMIC FIRE ELEMENT This element involves a qualitative review of potential interactions between an earthquake and fire that might contribute to plant risk.
This element does not include quantitative estimates of the risk associated with such interactions, but rather, seeks to ensure that such interactions have been considered and that steps are taken to ensure that the potential risk contributions are not significant.
HIGH LEVEL REQUIREMENTS FOR SEISMIC FIRE (SF)
HLR HLR Description HLR Summary (From Review)
HLR-SF-A The FPRA shall include a qualitative assessment of Oconee IPEEE conducted seismic - fire interaction evaluations that potential seismic-fire interaction issues in the FPRA. included walkdowns and resolution of findings. However, some standard required procedures have not been developed.
HLR-SF-B The FPRA shall document the results of the seismic-fire The seismic - fire interaction evaluation was documented with in interaction assessment in a manner that facilitates FPRA their IPEEE summary and reference site calculations.
applications, upgrades, and peer review.
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SUPPORTING REQUIREMENTS FOR SEISMIC FIRE SR Level Observation Basis Cap Cat SF-A1 Summary As part of the IPEEE, each zone was walked down Met to determine if there was a potential for a seismic event to damage equipment resulting in fire ignition, propagation, increased fire hazard, or cause a PRA Event.
SF-A2 Finding A seismic induced assessment of the potential for F&O SF-A2-1 Not Met diversion of suppressants from areas where needed for fire suppression systems associated with a common suppressant supply was not conducted.
SF-A3 Summary The IPEEE review of seismic/fire evaluation did not Met include an assessment of the potential for common-cause failure of multiple fire suppression systems due to the seismically-induced failure of supporting systems such as fire pumps, fire water storage tanks, yard mains, gaseous suppression storage tanks, or building stand-pipes.
However, Oconee fire brigade response procedure and mutual aid agreement is designed for the loss of fire fighting water event and the ability to use portable water pumps or offsite fire department fire trucks to pump lake water to conduct fire fighting.
SF-A4 Finding The plant seismic response procedures covers F&O SF-A4-1 Not Met seismically induced flooding, but not seismically induced fire.
SF-A5 Finding No assessment has been conducted on the F&O SF-A5-1 Not Met potential that an earthquake might compromise one or more of the fire brigade.
SF-B1 Summary The seismic/fire interface review was done in the Met 90's as part of the IPEEE and the results are documented in a number of places that are accessible for review within the site NEDL system.
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :SF-A2-1 Level of Significance: Finding Reviewer: PWL Capability Category: Not Met OBSERVATION:
The potential for fire protection systems water piping failure during a seismic event was investigated as part of the seismic walkdowns. Fire protection control panels and actuation devices were review to determine if a seismic event would cause an inadvertent actuation.
Deluge valves were identified as not being seismically qualified, but it was noted transformers were not effected by actuation of the deluge system. The potential for fire protection water piping failures was investigated resulting is several recommended upgrades.
Seismically induced inadvertent actuation of CO2 suppression systems causing loss of habitability was not specifically addressed, but Oconee has developed a fire brigade guide to address fire response to bulk CO2 dumps.
A seismic induced assessment of the potential for diversion of suppressants from areas where they might be needed for those fire suppression systems associated with a common suppressant supply was not conducted.
BASIS FOR LEVEL OF SIGNIFICANCE:
A seismic induced assessment of the potential for diversion of suppressants from areas where needed for fire suppression systems associated with a common suppressant supply was not conducted.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. IPEEE Submittal Report Harold Lefkowitz
- 2. OSS-0254
- 3. OSC-6048
- 4. OSC-5995
- 5. Fire Brigade Guide SOG #15
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 4 Date: 3/19/2008 ID Number :SF-A4-1 Level of Significance: Finding Reviewer: PWL Capability Category: Not Met OBSERVATION:
The plant seismic response procedures covers seismically induced flooding, but not seismically induced fire.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. IPEEE Submittal Report Harold Lefkowitz
- 2. AP/0/A/1700/005
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :SF-A5-1 Level of Significance: Finding Reviewer: PWL Capability Category: Not Met OBSERVATION:
The Fire Pre-Plans do not specifically address seismically induced fire response, but does cover responses to seismically induced fire events like inadvertent CO2 dumps and fires in zones containing safe-shutdown equipment. Fire Brigade equipment is available onsite and in remote locations. No assessment has been conducted on the potential that an earthquake might compromise one or more of these features.
BASIS FOR LEVEL OF SIGNIFICANCE:
No assessment has been conducted on the potential that an earthquake might compromise one or more of the fire brigade.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Fire Pre-Plans Harold Lefkowitz
- 2. IPEEE Submittal Report
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FIRE RISK QUANTIFICATION ELEMENT This element involves the quantification and presentation of fire risk results. In this element the FPRA plant response model (developed under element PRM), modified to include additional HFEs as identified in the HRA, is exercised for each fire scenario (as defined in element FSS). CCDP and CLERP values are calculated based on translation of the cable and equipment failures for each scenario, including specification of the failure modes, into PRM basic events, quantitative equipment failure mode values (from element CF), and HEP values (from element HRA). Final quantification mathematically combines the calculated CCDP/CLERP values with the corresponding fire frequency (IGN) and the conditional probability of fire damage (potentially including both a severity factor and non-suppression probability (FSS)) to yield estimates of fire risk in the form of CDF and LERF.
HIGH LEVEL REQUIREMENTS FOR FIRE RISK QUANTIFICATION (FQ)
HLR HLR Description HLR Summary (From Review)
HLR-FQ-A Quantification of the FPRA shall quantify the fire-induced The chosen analysis method did not identify the initiating events CDF. caused by a fire at each ignition source but, instead, failed the targets and relied on the logic model to yield the proper scenarios including identifying the required mitigating functions and using the appropriate success criteria for these functions. The internal events standard and, by reference, the fire standard uses initiating events as a basic logic model building blocks and quantitative reference points so the proposed method does not met the standard. The proposed method may be able to produce the correct quantitative result without meeting the standard. The review of the models was not sufficient to verify this level of detail during the site audit.
HLR-FQ-B The fire-induced CDF quantification shall use appropriate Integration performed using same logic models and code package models and codes, and shall account for method specific as internal events.
limitations and features.
HLR-FQ-C Model quantification shall determine that all identified Using nominal HEPs during quantification can result in cutsets dependencies are addressed appropriately. being truncated. Rule Based Recovery (RBR) will not correct this, since the cutsets are not present in the results and this HLR is not met.
HLR-FQ-D The frequency of different containment failure modes There are no intermediate core damage states. Fault trees leading to a fire-induced large early release shall be generally resulting in high or low vessel pressure at vessel failure quantified and aggregated thus determining the fire- are "anded" directly with basic events containing a generic induced LERF. conditional containment probability given high versus low pressure event. Although this yielded LERF results for all sequences,
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HIGH LEVEL REQUIREMENTS FOR FIRE RISK QUANTIFICATION (FQ)
HLR HLR Description HLR Summary (From Review) inconsistencies were identified in the LER results which the utility was not able to resolve during the audit. The LERF analysis is incomplete so this HLR is not met.
HLR-FQ-E The fire-induced CDF and LERF quantification results The proposed method produces significant fire location and shall be reviewed and significant contributors to CDF and accident sequence contributors and may be able to produce the LERF, such as fires and their corresponding plant initiating correct quantitative result without meeting the standard. The review events, fire locations, accident sequences, basic events of the models was not sufficient to verify this level of detail during (equipment unavailability and human failure events), plant the site audit.
damage states, containment challenges and failure modes, shall be identified. The results shall be traceable to the inputs and assumptions made in the FPRA.
HLR-FQ-F The CDF and LERF analyses shall be documented The documentation needs to be improved so that a knowledgeable consistent with the applicable SRs. peer reviewer can readily understand how the fire PRA is quantified. In a number of areas, the documentation was not adequate for the reviewers to readily determine compliance with the standard; refer to finding F&O FQ-F1-1.
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SUPPORTING REQUIREMENTS FOR FIRE RISK QUANTIFICAITON SR Level Observation Basis Cap Cat FQ-A1 Summary Cable/ignition source/component data bases Met appropriately link the failures into the basic events and can substitute failed (or circuit failure probabilities) into the model. The substitution is done before the model is reduced and quantified.
FQ-A2 Finding Fire scenarios frequencies are documented and F&O FQ-A2-1 Not Met reported based on PAU and/or ignition source.
The corresponding Failed components are identified, but there is no identification of which initiating event is initiated by the fire.
FQ-A3 Summary Assembled and integrated by the software Met package used.
FQ-A4 Summary Quantification using only point estimates so Met Corresponds to capability category 1 from internal events SR QU-A2b.
FQ-A4 (internal events SR referenced by FQ-A4) Met QU-A1 Integration performed using same code package as internal events. Throughout the study specific initiating events are not used. Alternative method of failing equipment can result in the correct numerical results.
FQ-A4 (internal events SR referenced by FQ-A4) Met QU- Licensee used plant wide fault tree method, not A2a linked fault trees or split fractions.
FQ-A4- (internal events SR referenced by FQ-A4) Point 1 QU- estimate only.
A2b FQ-A4 (internal events SR referenced by FQ-A4) Same Met QU-A3 code package used for internal events.
Discrimination down to basic event level.
FQ-A4 (internal events SR referenced by FQ-A4) HEP Met QU-A4 modified by generic factors associated with fire effects, not scenario specific modifications.
FQ-B1 Finding Internal events QU-B3 is incorporated by F&O FQ-B1-1 Not Met reference and is not met: An iterative demonstration of convergence versus truncation level has not yet been performed.
FQ-B1 (internal events SR referenced by FQ-B1) Used Met QU-B1 same code package as used for internal events.
FQ-B1 (internal events SR referenced by FQ-B1) Used, Met QU-B2 in general, 1E-8 for CCDP, which is an effective CDF cutoff of several orders of magnitude lower (depending on the fire ignition frequency). Based on looking at a range of CCDP values, this cutoff appears acceptable.
FQ-B1 (internal events SR referenced by FQ-B1) An F&O FQ-B1-1 Not Met QU-B3 iterative demonstration of convergence versus truncation level has not yet been performed.
FQ-B1 (internal events SR referenced by FQ-B1) The Met
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SUPPORTING REQUIREMENTS FOR FIRE RISK QUANTIFICAITON SR Level Observation Basis Cap Cat QU-B4 code package uses min-cut upper bound (MCUB).
FQ-B1 (internal events SR referenced by FQ-B1) Utility N/A QU-B5 and contractors stated that no new models were needed.
FQ-B1 (internal events SR referenced by FQ-B1) Done Met QU-B6 through use of "one top gate" model.
FQ-B1 (internal events SR referenced by FQ-B1) Met QU- Evaluation performed and documented. Mutually B7a exclusive events (valve fails open/valve fails closed) were left in the model except for PORV.
Statement made that all other mutually exclusive events are insignificant.
FQ-B1 (internal events SR referenced by FQ-B1) Met QU- Mutually exclusive cutsets are deleted using the B7b rule based recovery file.
FQ-B1 (internal events SR referenced by FQ-B1) The Met QU-B8 model is being solved setting failed equipment to TRUE and then solved again, as a logic check, with the failed equipment set to 1.0.
FQ-B1 (internal events SR referenced by FQ-B1) N/A QU-B9 Modules, subtrees, or split fractions are not used to facilitate the quantification.
FQ-C1 Finding Using nominal HEPs during quantification can F&O FQ-C1-1 Not Met result in cutsets being truncated. Rule Based Recovery (RBR) will not correct this, since the cutsets are not present in the results.
FQ-D1 Summary LERF is quantified with a large fault tree as is Met CDF. There are no intermediate core damage states. Fault trees resulting in high or low pressure core pressure ate vessel failure are "anded" directly with basic events containing a generic conditional containment probability given RCS pressure (0.05 given for high pressure and no Hot leg creep (0.70), and 0.01 given low pressure and some sequences with hot leg creep). As summarized in PRM-B1 Oconee used an inadequate version of the internal events model as the base model based on their failure to resolve multiple F&Os from the Maracor review.
There are many F&Os are related to the LERF analysis.
FQ-E1 Finding The chosen method (see PRM-FQ-A) does not F&O FQ-E1-1 Not Met produce different significant contributor categories to support results review. As of audit review, limited review of available results had been performed.
FQ-F1 Finding It is not possible to see the initiating event F&O FQ-F1-1 Not Met assigned to each scenario unless one looks in the cut-set output files and deduces the initiating event based on the failed equipment. Method
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SUPPORTING REQUIREMENTS FOR FIRE RISK QUANTIFICAITON SR Level Observation Basis Cap Cat used by the licensee can produce the correct numerical results without meeting the standard.
FQ-F2 Summary The fire PRA documentation did not claim that N/A referenced internal event HLRs and SRs were not applicable; therefore, this is not applicable.
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :FQ-A2-1 Level of Significance: Finding Reviewer: SCD Capability Category: Not Met OBSERVATION:
Fire scenarios frequencies are documented and reported based on PAU and/or ignition source.
The corresponding Failed components are identified, but there is no identification of which initiating event is initiated by the fire.
BASIS FOR LEVEL OF SIGNIFICANCE:
The internal events and the fire standard calls for indentifying the type of transient that would be initiated by the fire, where type of transient is normally associated with the internal events transients. A generic initiating event is assumed (e.g., plant trip) and any furter refinement of the initing event (e.g., SBO) is determined by the model and the equipment that is failed by the fire. This method does not evaluate the failures caused by the fire to indentify the type of transient and therefore this SR is not met.
POSSIBLE RESOLUTION (REVIEWER):
The method being employed is capable of giving the correct quantitative results.
Reference(s): Personnel Contacted:
- 1. R0237-05-0001.04, Table attachment A Kiang Zee Ed Simbles
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :FQ-B1-1 Level of Significance: Finding Reviewer: SCD Capability Category: Not Met OBSERVATION:
While the review team was onsite, the CCDP for two fire scenarios were run at differing truncation cutoffs. Changing the cutoff from 1E-8 to 1E-11 resulted in about a 1% increase in CCDP for one scenario and about a 4% increase in the second.
BASIS FOR LEVEL OF SIGNIFICANCE:
Internal events QU-B3 is incorporated by reference and is not met: An iterative demonstration of covergence versus truncation level has not yet been performed.
POSSIBLE RESOLUTION (REVIEWER):
Perform an analysis to demonstrate that the chosen truncation level is adequate.
Reference(s): Personnel Contacted:
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/19/2008 ID Number :FQ-C1-1 Level of Significance: Finding Reviewer: SCD Capability Category: Not Met OBSERVATION:
HFE dependencies are handled via post-processing using a rule-based recovery file. The fire results available to the team used non-conservative, base HEPs for solution of the model. The RBR file then would apply multipliers to cutsets containing multiple HFEs. (Some of these multipliers are above 5E+8.)
BASIS FOR LEVEL OF SIGNIFICANCE:
Using nominal HEPs during quantification can result in cutsets being truncated. Rule Based Recovery (RBR) will not correct this, since the cutsets are not present in the results for application of the multiplier. Also, even using higher HEPs and then re-setting them to nominal HEPs in the RBR process, followed by addition of "multiplier" events to get the correct number, has another potential problem: New combinations of HEPs that might be dependent will be low in the cutset file or truncated. The opposite approach, where operator actions get set to 1.0 in the recovery process and the joint HEP for the dependent group is applied (as a fraction) has the advantage that new, un-analyzed combinations show up in a conservative manner and, if important to the results, will be noted by the analyst so that dependency can be assessed.
POSSIBLE RESOLUTION (REVIEWER):
Use high, screening HEPs during quantification to avoid losing cutsets to truncation. [Note:
Licensee provided a sensitivity that showed, re-solving all fire sequences with HEPs set to 0.1 and then resetting to nominal in the results, followed by application of the recovery rules, did result in an increase in calculated CCDP. The increase over all scenarios was about 3%, with some low probability CCDPs having a large increase percentage-wise but small in absolute value.
Reference(s): Personnel Contacted:
- 1. or3aboth%.txt (RBR file)
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/20/2008 ID Number :FQ-E1-1 Level of Significance: Finding Reviewer: SCD Capability Category: Not Met OBSERVATION:
The chosen method neither uses nor produces results that include initiating events. Other contributor categories such as plant damage states, containment challenges and failure modes were not available and may be difficult or impossible to extract without modifying the model logic and quantification process. As throughout the FPRA, results are disucssed in terms of ignition sources within each location and the equipment that is damaged from that location. The initiating event caused by the fire is not normally available.
CDF and LERF cutsets that should be the same aside from the multiplier were not always the same. Some additional cuts sets were identified in the LERF tree (Note that two different CDF trees are used during quantification, one for CDF and another for LERF)
Some observations (such as difference in cut sets) were new to the licensee. Importance measures have not been generated.
BASIS FOR LEVEL OF SIGNIFICANCE:
Results identifying significant contributores not available (aside from ignition sources). Insights sections do not include LERF insights. Inconsistencies in documeted results (such as unexpectde difference in CDF and LERF cut-set) were new to the licensee. Several computer calculations intended to to help clarify reuslts failed to run propoerly.
POSSIBLE RESOLUTION (REVIEWER):
It was apparent that litle time for reveiw of results was avaiable before audit. Utility should complete a detailed review of the different results to provide conifidence that the models are correct.
Reference(s): Personnel Contacted:
- 1. R0237-05-0001.06, Appendix C
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/17/2008 ID Number :FQ-F1-1 Level of Significance: Finding Reviewer: SCD Capability Category: Not Met OBSERVATION:
The only results normally available are cut sets associated with each ignition source. It is not possible to determine which initiating event is caused by an ignition source without looking at the ones-runs cut set files. Ones-runs are used moslty as a sensitivity study and are sometimes unstable Method used by the licensee can produce the correct numerical results.
BASIS FOR LEVEL OF SIGNIFICANCE:
Method selected by utility does not result in documentation of results according to the Standard because initiating events and other sequence characteristics are not available. Method can yield the correct numerical results.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
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UNCERTAINTY AND SENSITIVITY ANALYSIS ELEMENT This element involves the identification and treatment of uncertainties throughout the FPRA process.
HIGH LEVEL REQUIREMENT FOR UNCERTAINTY AND SENSITIVITY ANALYSIS (UNC)
HLR HLR Description HLR Summary (From Review)
HLR-UNC-A The FPRA shall identify key sources of CDF and LERF Not reviewed. The analysis is not yet at the stage where the uncertainties, including key assumptions and modeling assessment of parameter uncertainty is necessary. However, this approximations. These uncertainties shall be will be met only to the extent that the other SRs identified are met.
characterized such that their impacts on the results are understood.
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SUPPORTING REQUIREMENTS FOR UNCERTAINTY AND SENSITIVITY SR Level Observation Basis Cap Cat UNC- Finding Not reviewed. When the analysis is complete and UNC-A1-1 Not Rev A1 stable, the sources of model uncertainty should be identified.
UNC- Finding Not reviewed. The analysis is not yet at the stage UNC-A1-1 Not Rev A2 where the assessment of parameter uncertainty is necessary. However, this will be met only to the extent that the other SRs identified are met.
UNC- Summary This was not reviewed, since it the intent of the N/A A3 staff to take exception to this as being unnecessary in the context of the base PRA.
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 03/20/2008 ID Number: UNC-A1-1 Level of Significance: Finding Reviewer: GWP Capability Category: Not Met (not reviewed)
OBSERVATION:
In the NRC's comments on the combined standard, the descriptor "key" associated with a source of uncertainty or related assumption is recommended to be dropped. Key is defined only within the context of an application, where it is used to identify those sources of uncertainty that can change the decision. The staff expects that this SR will be met by identifying the sources of model uncertainty.
The fire PRA is still in the process of development, and therefore it is difficult to assess this SR.
This will be achieved consistent with the identification of sources of model uncertainty in the constituent elements of the fire PRA. For example, the current status of the fire PRA is such that the fire modeling is primarily conservative or screening in nature. The fire modeling report (Hughes generic treatment) does identify sources of model uncertainty and lists assumptions that are used in the use of the model. The treatment of uncertainty for ignition frequencies follows that in NUREG/CR-6850.
When the analysis is complete and stable, the sources of model uncertainty should be identified.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Perform the tasks associated with fire PRA standard element UNC and document. Self-assess to HLR UNC-A and the associated supporting requirements. Have the completed work peer reviewed per the fire PRA standard requirements.
Reference(s): Personnel Contacted:
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PRA CONFIGURATION CONTROL AND MODEL UPDATE (This is required by the standard in Section 1-5, but not called out as an element)
HIGH LEVEL REQUIREMENTS FOR PRA CONFIGURATION CONTROL/MODEL UPDATE (MUD)
HLR HLR Description HLR Summary (From Review)
HLR-MUD-A A process for monitoring FPRA inputs and collecting new This requirement was met. Two suggestions were made. The first information is to provide procedural guidance on how to capture general industry events, operating experience feedback, or other information that could challenge PRA model assumptions, point to new failure modes or mechanisms, or reveal new event scenarios.
The second is to add the requirement to monitor updated or new methods. Refer to F&O suggestions MUD-A3-1 and MUD-A3-2.
HLR-MUD-B A process that maintains and upgrades the FPRA to be This requirement was not met because the Oconee configuration consistent with the as-built, as operated plant control procedures do not reference the fire PRA standard or the supporting requirements therein. Refer to F&O finding MUD-B4-1.
HLR-MUD-C A process that ensures that the cumulative impact of This requirement was met.
pending changes is considered when applying the FPRA HLR-MUD-D A process that evaluates the impact of changes on This requirement was met. One requirement that is currently in the previously implemented risk-informed decisions that have standard, to assess past risk-informed applications when the PRA used the FPRA model is updated or upgraded, is slated for removal from the PRA standard in a future revision. The Oconee configuration control procedure does include such a requirement for applications listed an enclosure.
HLR-MUD-E A process that maintains configuration control of computer This requirement was not met because the FRANC computer code codes used to support FPRA quantification had not been qualified as required by procedure. Refer to finding F&O MUD-E1-1.
HLR-MUD-F Documentation of the Program This requirement was met.
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SUPPORTING REQUIREMENTS FOR CONFIGURATION CONTROL/MODEL UPDATE SR Level Observation Basis Cap Cat MUD- Summary XSAA-104 requires monitoring plant experience Met A1 for impact on PRA IE and failure rate data based on a review of the PIP (corrective action program) database. XSAA-110 has limited guidance to look for IE and failures that should be incorporated into the data update. No evidence of industry-wide operational history monitoring. XSAA-101 monitors plant hardware changes, TS changes, EP, AP changes and industry events (references NSD 415 - not reviewed). Checklist in Ref XSAA-101 includes impact on fires, floods, seismic, tornados as well as internal events MUD- Summary See MUD-A2 for detailed discussion. Met A2 MUD- Suggestion Add procedural guidance on how to capture F&O MUD-A3-1 Met A3 general industry events, operating experience feedback, or other information that could challenge PRA model assumptions, point to new failure modes or mechanisms, or reveal new event scenarios do not appear to be captured in the procedures. Note that fire-specific guidance is not provided.
MUD- Suggestion Suggestion: Add language to monitor updated F&O MUD-A3-2 A3 or new methodologies as appropriate.
MUD- Suggestion The fire PRA being developed to support F&O MUD-B1-1 Met B1 NFPA-805 transition is not specifically included in the scope of the model update procedures.
MUD- Summary XSAA-106 does not specifically include the fire Met B2 PRA being developed to support NFPA-805 transition. Refer to F&O MUD-B1-1.
MUD- Summary XSAA-106 does not specifically include the fire Met B3 PRA being developed to support NFPA-805 transition. Refer to F&O MUD-B1-1.
MUD- Finding Fire standard needs to be referenced in XSAA- F&O MUD-B4-1 Not Met B4 106 and the fire PRA model should be explicitly in the scope of the procedure.
MUD- Summary See F&O MUD-B4-1 for discussion regarding F&O MUD-B4-1 Not Met B5 lack of reference of fire or combined PRA standard.
MUD- Summary See F&O MUD-B4-1 for discussion regarding F&O MUD-B4-1 Not Met B6 lack of reference of fire or combined PRA standard.
MUD- Summary XSAA-106 covers this. As stated in F&O MUD- Met C1 B1-1, the fire PRA being developed to support NFPA-805 transition is not specifically included in the scope of the procedure and should be added to the scope.
MUD- Other XSAA-106 requires that risk applications in N/A D1 enclosure 3 be evaluated, and notes that the list is not all-inclusive. However, as noted in MUD-B4-1, the fire PRA model is not explicitly
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SUPPORTING REQUIREMENTS FOR CONFIGURATION CONTROL/MODEL UPDATE SR Level Observation Basis Cap Cat referenced in the procedure. Further, the NFPA-805 application is not within scope of the procedure. However, this is not a "finding' because this portion of the requirement is slated for removal from the PRA standard in a future revision.
MUD- Finding The FRANC computer code and corresponding F&O MUD-E1-1 Not Met E1 Microsoft Access databases have not been evaluated and documented at any software and data quality assurance (SDQA) classification per NSD-800.
MUD- Summary Met, based on review of Duke Energy Met F1 Carolinas, LLC procedures.
MUD- Summary Met, based on review of Duke Energy Met F2 Carolinas, LLC procedures.
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :MUD-A3-1 Level of Significance: Suggestion Reviewer: SAL Capability Category: Met OBSERVATION:
Suggestion: Although references to "industry experience" are made in the various procedures, very little guidance is given regarding what to monitor. It appears that new industry generic data reports, for example, or initiating event history, would be included in the review. However, general industry events, operating experience feedback, or other information that could challenge PRA model assumptions, point to new failure modes or mechanisms, or reveal new event scenarious do not appear to be captured in the procedures. Note that fire-specific guidance is not provided.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Provide direction in process to monitor industry wide operational history. Ensure that component data (generic and plant-specific) includes active fire protection systems, e.g. fixed suppression, dampers.
Reference(s): Personnel Contacted:
- 1. Workplace procedure XSAA-101, Rev 12, "Risk-Impact Review of Nuclear Plant Changes Including Nuclear Station Modification, and Emergency or Abnormal Procedure Changes"
- 2. Workplace procedure XSAA-104, Rev 6, "Evaluation of Operating Experience Events"
- 3. Workplace procedure XSAA-106, Rev 15, "PRA Maintenance, Update and Application"
- 4. Workplace procedure XSAA-110, Rev 4, "Developing PRA Data"
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :MUD-A3-2 Level of Significance: Suggestion Reviewer: SAL Capability Category:
OBSERVATION:
Suggestion: Add language to monitor updated or new methodologies as appropriate Currently, XSAA-106 does not have language to use updated or new methodologies which reflect current industry and requirements as appropriate.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Workplace procedure XSAA-101, Rev 12, "Risk-Impact Review of Nuclear Plant Changes Including Nuclear Station Modification, and Emergency or Abnormal Procedure Changes"
- 2. Workplace procedure XSAA-104, Rev 6, "Evaluation of Operating Experience Events"
- 3. Workplace procedure XSAA-106, Rev 15, "PRA Maintenance, Update and Application"
- 4. Workplace procedure XSAA-110, Rev 4, "Developing PRA Data"
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :MUD-B1-1 Level of Significance: Suggestion Reviewer: SAL Capability Category: Met OBSERVATION:
XSAA-106 covers this in detail, requiring both periodic PRA model updates and interim updates if significant changes to the plant are made. XSAA-101 ensures that plant changes, including TS and procedures, are evaluated for impact on the PRA model. Fires are mentioned, although in a cursory manner. The fire PRA being developed to support NFPA-805 transition is not specifically included in the scope of the procedure. EDM-601 Appendix K.8 provides a checklist for fire protection features to be considered when engineering changes are developed.
EDM-601 Appendix N provides a checklist for fire protection electrical reviews that refers the designer to the PRA group.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
The ASME combined PRA standard needs to be referenced in XSAA-106. The fire PRA model should be explicitly included within the scope of the procedure.
Reference(s): Personnel Contacted:
- 1. Workplace procedure XSAA-101, Rev 12, Brandi Weaver "Risk-Impact Review of Nuclear Plant Changes Including Nuclear Station Modification, and Emergency or Abnormal Procedure Changes"
- 2. Workplace procedure XSAA-104, Rev 6, "Evaluation of Operating Experience Events"
- 3. Workplace procedure XSAA-106, Rev 15, "PRA Maintenance, Update and Application"
- 4. Workplace procedure XSAA-110, Rev 4, "Developing PRA Data"
- 5. EDM-601 Rev 7, "Engineering Change Manual"
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :MUD-B4-1 Level of Significance: Finding Reviewer: SAL Capability Category: Not Met OBSERVATION:
Only the internal events PRA standard is referenced. Since the combined standard or fire standard is not referenced, those SRs are not evaluated. Fire standard needs to be referenced in XSAA-106 and the fire PRA model should be explicitly in the scope of the procedure.
BASIS FOR LEVEL OF SIGNIFICANCE:
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Workplace procedure XSAA-106, Rev 15, "PRA Maintenance, Update and Application"
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FACT/OBSERVATION REGARDING FIRE PRA (FPRA)
TECHNICAL ELEMENTS Plant Name: Oconee 3 Date: 3/18/2008 ID Number :MUD-E1-1 Level of Significance: Finding Reviewer: SAL Capability Category: Not Met OBSERVATION:
XSAA-106 states that PRA codes are under the software QA program in accordance with procedure NSD-800. NSD-800 defines SDQA Classification C as including "software or data that is used to meet a licensing commitment or monitor licensing compliance activities without alternative methods to verify the results." Based on conversation with licensee personnel, the FRANC computer code and corresponding Microsoft Access databases have not been evaluated and documented at any SDQA classification per NSD-800.
BASIS FOR LEVEL OF SIGNIFICANCE:
This is a finding because the FRANC software and corresponding databases are relied upon to map specific fire events and impacts into the PRA CAFTA model, call the quantification engine, and display the results. FRANC also performs nominal calculations such as multiplying CCDP by severity factor, fire ignition frequency, etc.
POSSIBLE RESOLUTION (REVIEWER):
Reference(s): Personnel Contacted:
- 1. Workplace procedure XSAA-106, Rev 15, Brandi Weaver "PRA Maintenance, Update and Application"
- 2. NSD 801 Rev 11, "Software and Data Quality Assurance (SDQA) Program