ML12131A492
| ML12131A492 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 05/11/2012 |
| From: | Jacqueline Thompson Plant Licensing Branch II |
| To: | Morris J Duke Energy Carolinas |
| Thompson J | |
| References | |
| TAC ME7659, TAC ME7660 | |
| Download: ML12131A492 (9) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 11ly 2012 Mr. J. R. Morris Site Vice President Catawba Nuclear Station Duke Energy Carolinas, LLC 4800 Concord Road York, SC 29745
SUBJECT:
CATAWBA NUCLEAR STATION, UNITS 1 AND 2 (CATAWBA 1 AND 2),
REQUEST FOR ADDITIONAL INFORMATION (RAI) REGARDING LICENSE AMENDMENT RELATED TO REQUEST TO REVISE TECHNICAL SPECIFICATION (TS) 3.7.8, NUCLEAR SERVICE WATER SYSTEM (NSWS)
(TAC NOS. ME7659 AND ME7660)
Dear Mr. Morris:
By letter dated November 22,2011, Duke Energy Carolinas, LLC (the licensee), submitted a proposed license amendment to change the Catawba 1 and 2 TSs. The proposed change would revise TS 3.7.8 to allow single discharge header operation of the NSWS for a time period of 14 days.
The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the licensee's submittal and determined that additional information is needed in order to complete our review. The enclosed document describes this RAt. A written response should be provided to the NRC staff within 30 days of the issuance of this letter in order to support our timely review of this application. Please inform me if you are unable to support this response timeframe.
If you have any questions, please call me at 301-415-1345.
Sincerely, Jon Thompson, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-413 and 50-414
Enclosure:
As stated cc w/encl: Distribution via Listserv
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 REQUEST FOR ADDITIONAL INFORMATION (RAI)
BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING LICENSE AMENDMENT RELATED TO REVISION OF THE TECHNICAL SPECIFICATION (TS) 3.7.8 TO ALLOW SINGLE DISCHARGE HEADER OPERATION OF THE NUCLEAR SERVICE WATER SYSTEM (NSWS) FOR A TIME PERIOD OF 14 DAYS CATAWBA NUCLEAR STATION, UNITS 1 AND 2 (CATAWBA 1 AND 2)
DOCKET NOS. 50-413 AND 50-414 By letter dated November 22, 2011, (Agencywide Document Access and Management System Accession No. ML11327A149), Duke Energy Carolinas, LLC (Duke Energy or the licensee),
submitted a proposed license amendment request (LAR) in the form of changes to the Technical Specifications (TSs) for Catawba 1 and 2. The proposed LAR would revise TS 3.7.8 to allow single discharge header operation of the NSWS [Nuclear Service Water System] (Duke Energy designation "RN") for a time period of 14 days.
To complete its review, the U.S. Nuclear Regulatory Commission (NRC) staff requests the following additional information:
- 1. According to the LAR, the licensee concludes that "the NSWS single discharge header alignment supports operation in this configuration... [and] the increase in risk... is minimal and acceptable." Provide the quantitative results that are being compared against the Regulatory Guide (RG) 1.177 and RG 1.174 acceptance guidelines.
- 2. RG 1.200 states "A peer review is needed to determine if the intent of the requirements in the standard is met." The standard referred to is the American Society of Mechanical Engineers (ASME) and American Nuclear Society (ANS) probabilistic risk assessment (PRA) standard that provides both process and technical requirements for an at-power Level 1 and limited Level 2 PRA for internal events, internal flood, internal fire, seismic, wind, external flood and other external events. RG 1.200 also states that "The results of the peer review and/or self-assessment, and a description of the resolution of all the peer review or self-assessment findings and observations are included."
- a. The submittal does not address an independent peer review according to the ASME/ANS PRA Standard, for any of the hazard groups, including internal events. The NRC staff expects applications to have had PRA peer reviews of all Enclosure
- 2 potentially significant hazard groups for an application. Please indicate what were the findings and observations of these reviews and how they were dispositioned for this application.
- b. The licensee states that the "[self] assessment indicated that 231 of the 306 Supporting Requirements (SRs) for Rev. 1 were fully met [but] 24 of the SRs were not applicable to Catawba [1 and 2] at aiL" However, only 10 SRs were actually considered to have an impact on the PRA model and were addressed in the submittal. Please provide a detailed list addressing all SRs that were not met in the self assessment.
- c. In this risk-informed submittal, the licensee makes use of a self assessment that should only be used if it builds off of an independent full scope peer review. To use this self assessment, the license~ would need to describe and provide the results of (and disposition of) any findings from the full scope peer review.
Furthermore, if there has been a PRA upgrade (as defined in the NRC-endorsed ASME/ANS-RA-Sa-2009) since the latest full scope peer review, a focused scope peer review of the upgraded areas would be needed. Please provide information regarding any full-scope independent peer review findings and dispositions relevant to this LAR. Also, if there have been any upgrades to the PRA since the last full scope independent peer review, please describe the upgrades and provide information on the associated focused scope peer review, including findings and dispositions relevant to this LAR.
- 3. According to the submittal, the seismic analysis of the NSWS components and piping caused "the seismic [cord damage frequency] CDF [to show] only a modest increase using very conservative bounding assumptions... [due to] a sensitivity study [that] was performed to conservatively bound the impact of having a NSWS discharge line unavailable during a seismic event." Please provide a description of the change in seismic analysis and the resulting seismic CDF and [large early release frequency]
LERF for this application.
- 4. Please provide a description of the internal fire PRA analysis and resulting change in internal fire CDF and LERF for this application.
- 5. Please provide a description of the internal/external floods PRA analysis and resulting change in internal flooding CDF and LERF for this application.
- 6. Please provide a description of the tornado/high winds PRA analysis and resulting change in the tornado/high winds CDF and LERF for this application.
- 7. Background The guidelines of RG 1.177 state that one of the elements of consistency with defense in-depth philosophy is maintaining "defenses against potential common-cause failures (CCFs).... " In the proposed new Condition C for TS 3.7.8 only one path of NSWS
- 3 discharge flow to the standby nuclear service water pond (SNSWP) is available when one NSWS header is isolated between 1 RPN-19 to 1 RN63A or between 1RPN-20 to 1 RN58B and flow is blocked to Lake Wylie.
If the only operable NSWS discharge header, as described above, had a pipe break or became blocked or became inoperable, all NSWS cooling could stop.
Request a)
Discuss your contingency plans, training, procedures, and compensatory measures to restore NSWS and maintain core and spent fuel pool cooling, in the event that this sole return to the SNSWP unexpectedly breaks/cracks or becomes flow blocked causing a total loss of NSWS cooling.
b)
Discuss any other possible CCF and associated contingency plans, training, procedures and compensatory measures or discuss why other CCF's do not exist.
- 8. Backqround Proposed new Condition C defines a new TS Condition statement where a NSWS discharge header is inoperable. This condition makes the associated NSWS train for Catawba 1 inoperable, causing a condition that does not meet the limiting condition for operation (LCO). Cases 1 and 2 as shown in the LAR on attachment 1, page 17, describe initial conditions for new Condition C.
The licensee is additionally placing a Catawba 2 diesel generator (DG) and a Catawba 2 NSWS pump out of service as an initial condition and calling this a single failure. Single failures are normally failures that are postulated to occur after a design basis accident, not as initial conditions.
Request Please explain:
a) Why are DGs and NSWS pumps placed out of service for maintenance and called single failures? [in the initial conditions and Note 9 of cases 1 and 2]
b) Since DGs 2A and 2B can discharge to the SNSWP downstream of 1 RN63A and 1 RN58B, and apparently do not have to be out of service, why are they assumed to be unavailable?
- 4
- 9. Background The licensee is proposing a single discharge header alignment to allow a portion of each of the NSWS return headers in the Auxiliary Building to the SNSWP to be removed from service for cleaning, repairing, coating and inspecting. The licensee has stated these activities "will ensure the long-term reliability of the NSWS."
The proposal addresses the short length of NSWS piping in the Auxiliary Building, while most of the NSWS discharge piping to the NSWSP and Lake Wylie is outside the Auxiliary Building.
Request a) Explain how the work on the short length of piping in the Auxiliary Building ensures long term reliability of the NSWS, when most of the pipe is outside the Auxiliary Building.
b) What will be done to clean, repair, coat and inspect the NSWS piping outside the Auxiliary Building?
- 10. Background During the proposed single discharge header lineups, valves 1 RN63A, 1 RN58B, 1RPN19A and 1 RPN20 isolate the pipe to be worked and form single valve barriers from Lake Wylie and the SNSWP to the Auxiliary Building.
Failure of any of the valves or personnel error could allow flooding into the Auxiliary Building.
Request a) Discuss the elevation of the work boundaries 1 RN63A, 1 RN58B, 1 RPN19A and 1 RPN20 as compared to the maximum elevation of the SNSWP and the maximum elevation of discharge pipes to the SNSWP. Describe design features that will prevent the SNSWP and/or NSWS discharge piping from draining into the Auxiliary Building if work boundaries failedlleaked or personnel error breached the work boundary.
b) Discuss additional backup isolation features and compensatory measures to prevent internal flooding.
- 5
- 11. Background The LAR describes two cases of single discharge header operation, i.e. a) pipe between 1 RPN63A and 1RPN19 is isolated, and b) pipe between 1RPN 58B and 1 RPN20 is isolated. In each case NSWS return header crossover valves are open with power removed; the NSWS return isolation valve to the SNSWP is open (power removed); NSWS suction is aligned to the SNSWP; and Lake Wylie discharge isolation valves are closed.
The updated facility safety analysis report (UFSAR) refers to the NSWS discharge headers as the A header and the B header, each serving both units.
The LAR description and the proposed new Insert 2 for the proposed TS Bases refer to both headers as the Catawba 2 discharge headers.
New Condition C of the proposed TS refers to them individually as one NSWS Auxiliary Building discharge header.
The above descriptions of the NSWS discharge headers in the TS Bases and new Condition C are unclear without reading the LAR. New Condition C and the Bases (Insert 3) do not define which portion of the discharge is allowed to be inoperable and the special lineup for safety that is described in the LAR. Therefore, operators may be inconsistent in plant configuration when entering new Condition C. Inspectors may not be able to know valid Condition C lineups.
Request Explain the licensee's intent to adequately define single discharge header operation in the UFSAR, new Condition C, and TS Bases, so that operators can align the plant to meet new Condition C as defined in the LAR when allowed, and inspectors can know the required discharge header alignment when in new Condition C.
- 12. Background Insert 2 of the proposed TS Bases describes the NSWS operating in the single discharge header alignment. This places Catawba 1 in new Condition C of the proposed TS which describes a condition where LCO 3.7.8 is not met. However, Insert 2 also says that each NSWS train is operable.
a) The licensee has placed the proposed Insert 2 for the single discharge header lineup in the LCO section of the TS Bases. However, as stated above, the single discharge header lineup does not meet the LCO.
- 6 b) Insert 2 states that each NSWS train is operable. Yet, Insert 2 describes Condition C which does not meet the LCO. Therefore, not all NSWS trains would be operable.
Throughout the LAR, the licensee lists either NSWS 1A or 1 B train as inoperable when in the single discharge header lineup. Thus Insert 2 conflicts with the background/technical evaluation in the LAR.
Request Explain the inconsistencies in the location of Insert 2 in the TS Bases and the content of Insert 2 as described above in a) and b) and correct Insert 2 as appropriate.
- 13. Background When in a single discharge header lineup, the background/technical sections of the LAR state that Catawba 2 must be in Mode 5, 6 or no Mode.
New Condition C of the TS as proposed in Insert 1 does not specifically require that Catawba 2 be in Mode 5, 6 or no Mode.
Request Explain why new Condition C of the TS does not require that Catawba 2 be in Mode 5, 6, or no Mode.
- 14. Background Insert 3 of the LAR states"... Condition C is only allowed to be entered in support of planned maintenance or modification activities associated with the Auxiliary Building discharge header that is taken out of service. An example of a situation for which entry into this Condition is allowed is refurbishment of an Auxiliary Building discharge header.
Entry into this Condition is not allowed in response to unplanned events or for other events involving the NSWS."
The LAR cover letter and description describes the proposed scope to be for the NSWS discharge header to be removed from service for cleaning. coating and follow-up inspections.
Insert 3 defines the allowed entry into Condition C to be much broader than the scope delineated in the rest of the LAR.
Request Explain how you will modify Insert 3 to be in consistent with the rest of the LAR.
- 7
- 15. Background The guidelines of RG 1.177 state that the licensee "should consider... whether there are appropriate restrictions in place to preclude simultaneous equipment outages that would erode the principles of redundancy and diversity," and "whether compensatory actions to be taken when entering the modified [completion time] CT for preplanned maintenance are identified."
When operating in a single discharge header as proposed by the LAR, one NSWS train is inoperable. NSWS is a support system. In accordance with TS 3.0.6, the corresponding supported systems are required to be declared inoperable if determined to be inoperable as a result of the support system inoperability. Supported systems include Emergency Core Cooling System, Containment Spray System, Containment Valve Injection Water System, Auxiliary Feedwater, Component Cooling Water, Control Room Area Ventilation System, Auxiliary Building Filtered Ventilation Exhaust System, and Emergency Diesel Generators.
The licensee has not identified any inoperable systems that are supported by NSWS in the LAR. The licensee has not expressed any compensatory measures to ensure the redundant trains of supported systems are protected to reduce the risk of loss of safety function. The licensee has not described any evaluation required by LCO 3.0.6 to perform an evaluation in accordance with TS Administrative Control 5.5.15, "Safety Function Determination Program (SFDP)" for supported systems.
Request Identify all inoperable supported system as a result of each inoperable NSWS train.
Identify all compensatory measure to protect the redundant system as determined by TS Administrative Control 5.5.15.
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- DATE 05/11/12 05/10/12 104/16/12 04130112 05/11/12 05/11/12