ML052520245
| ML052520245 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 09/22/2005 |
| From: | Dave Solorio Plant Systems Branch |
| To: | Marinos E NRC/NRR/DLPM/LPD2 |
| Whitney L, NRR/DSSA/SPLB, 415-3081 | |
| References | |
| BL-03-001, TAC MB9618, TAC MB9619 | |
| Download: ML052520245 (7) | |
Text
September 22, 2005 MEMORANDUM TO: Evangelos C. Marinos, Chief, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation FROM: David L. Solorio, Chief /RA/
Balance of Plant Section Plant Systems Branch Division of Systems Safety and Analysis Office of Nuclear Reactor Regulation
SUBJECT:
CLOSEOUT LETTER FOR BULLETIN 2003-01, POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY SUMP RECIRCULATION AT PRESSURIZED-WATER REACTORS The Plant Systems Branch (SPLB) has reviewed and evaluated the information provided in responses to Bulletin 2003-01 by the licensee for Surry Unit 1 and Unit 2. SPLB has determined that the licensees actions have been responsive to and meet the intent of Bulletin 2003-01. Attached to this letter is the proposed close-out letter for the above plants. If you have any questions, please contact Leon Whitney or Alan Wang. Please include Alan Wang and Leon Whitney on the distribution list.
Docket Nos: 50-280, 50-281
Attachment:
As stated CONTACTS: Leon Whitney, SPLB/DSSA 415-3081 Alan B. Wang, DLPM, PD IV 415-1445
September 22, 2005 MEMORANDUM TO: Evangelos C. Marinos, Chief, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation FROM: David L. Solorio, Chief /RA/
Balance of Plant Section Plant Systems Branch Division of Systems Safety and Analysis Office of Nuclear Reactor Regulation
SUBJECT:
CLOSEOUT LETTER FOR BULLETIN 2003-01, POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY SUMP RECIRCULATION AT PRESSURIZED-WATER REACTORS The Plant Systems Branch (SPLB) has reviewed and evaluated the information provided in responses to Bulletin 2003-01 by the licensee for Surry Unit 1 and Unit 2. SPLB has determined that the licensees actions have been responsive to and meet the intent of Bulletin 2003-01. Attached to this letter is the proposed close-out letter for the above plants. If you have any questions, please contact Leon Whitney or Alan Wang. Please include Alan Wang and Leon Whitney on the distribution list.
Docket Nos: 50-280, 50-281
Attachment:
As stated CONTACTS: Leon Whitney, SPLB/DSSA 415-3081 Alan B. Wang, DLPM, PD IV 415-1445 DISTRIBUTION:
LWhitney SMonarque Awang Accession No.: ML052520245 NRR-106 OFFICE DLPM/PDIV-2/PM DSSA/SPLB DSSA/SPLB NAME AWang LWhitney DSolorio DATE 09/ /05 09/ /05 09/ /05 OFFICIAL RECORD COPY
Virginia Electric and Power Company 5000 Dominion Boulevard Glen Ellen, VA 23060
SUBJECT:
SURRY UNIT 1 AND UNIT 2 - RESPONSE TO NRC BULLETIN 2003-01, POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY SUMP RECIRCULATION AT PRESSURIZED WATER REACTORS (TAC NO. MB9618 AND MB9619)
Dear Mr. Hartz:
This letter acknowledges receipt of your response dated August 7, 2003, to Nuclear Regulatory Commission (NRC)Bulletin 2003-01, Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized Water Reactors, dated June 9, 2003. The NRC issued Bulletin 2003-01 to all pressurized-water reactor (PWR) licensees requesting that they provide a response, within 60 days of the date of Bulletin 2003-01, that contains either the information requested in following Option 1 or Option 2 stated in Bulletin 2003-01:
Option 1: State that the emergency core cooling system (ECCS) and containment spray system (CSS) recirculation functions have been analyzed with respect to the potentially adverse post-accident debris blockage effects identified in the Discussion section, and are in compliance with all existing applicable regulatory requirements.
Option 2: Describe any ICMs that have been implemented or that will be implemented to reduce the risk which may be associated with potentially degraded or nonconforming ECCS and CSS recirculation functions until an evaluation to determine compliance is complete. If any of the interim compensatory measures (ICMs) listed in the Discussion section will not be implemented, provide a justification. Additionally, for any planned interim measures that will not be in place prior to your response to this bulletin, submit an implementation schedule and provide the basis for concluding that their implementation is not practical until a later date.
You provided an Option 2 response.
Bulletin 2003-01 discussed six categories of ICMs:
(1) operator training on indications of and responses to sump clogging; (2) procedural modifications if appropriate, that would delay the switchover to containment sump recirculation (e.g., shutting down redundant pumps that are not necessary to provide required flows to cool the containment and reactor core, and operating the CSS intermittently); (3) ensuring that alternative water sources are available to refill the RWST or to otherwise provide inventory to inject into the reactor core and spray into the containment atmosphere; (4) more aggressive ATTACHMENT
Mr. Hertz 2 containment cleaning and increased foreign material controls; (5) ensuring containment drainage paths are unblocked; (6) ensuring sump screens are free of adverse gaps and breaches.
You stated in your bulletin response of August 7, 2003, that you had implemented the following ICM:
(1) for small LOCAs where the pressurizer level can be maintained, ECCS injection is terminated as specified by procedure - ICM category #1; (2) for small LOCAs where pressurizer pressure remains above LHSI pump shutoff head, ECCS injection is systematically reduced from two trains to termination and charging is realigned from ECCS injection to the normal charging lineup - ICM category #1; (3) for loss of emergency coolant recirculation conditions, the strategy includes reduction of ECCS flow to one train, cycling the recirculation spray pumps to maintain containment pressure while minimizing flow, aligning alternate core coolant sources, refilling the refueling water storage tank (RWST) if the normal recirculation path is lost due to sump debris blockage, cross-connecting to the non-faulted units charging pump (as a source of charging pump discharge) or RWST (as a source of charging pump suction) - ICM category #1 and ICM category #3; (4) pre-RCS heatup containment inspection procedures which verify the containment free of debris - ICM category #4; (5) the use of significant amounts of floor grating outside of the crane wall, and gated doorways and floor gratings inside the crane wall to enhance drainage to the ECCS sump area - ICM category #5; (6) RCS heatup verification that the operating deck floor plugs are removed for RCS heatup -
ICM category #5, and verification that the refueling cavity transfer canal drain paths valve lineup is open - ICM category #5; (7) sub-atmospheric containment entry procedures to inspect entry and work areas for loose debris, and to obtain approval for equipment remaining in containment - ICM category #4; and (8) comprehensive sump structure inspection procedures each refueling outage against design requirements to detect and correct gaps or breaches - ICM category #6.
You also stated in your response that you would be implementing the following ICMs:
(1) enhancements to the Surry Power Station (SPS) EOPs to provide continuous monitoring of key sump performance indications and the streamlining of instructions to identify debris blockage and to prioritize sources of alternate core cooling (by March 31, 2004) - ICM category
- 1 and ICM category #3; and (2) informational briefings to operating staff to review Bulletin 2003-01 issues, key sump performance indicators to be monitored, and current procedures which respond to sump debris blockage - ICM category #1.
Mr. Hertz 3 You further stated in your response that any changes involving preemptive operator actions to shut off one train of ECCS would be considered after the Westinghouse Owners Group (WOG) evaluation of the generic impact of the changes. In that regard, in your response you stated, including justifications, that you would not be implementing the following ICM: preemptive operator actions to shut off one train of ECCS or quench spray to preserve RWST inventory prior to transfer to sump recirculation.
In an October 29, 2004, response to a September 2, 2004, NRC request for additional information (RAI), you described enhancements to the SPS EOPs that would decrease risk associated with potential sump blockage while not impacting the current symptom-based response strategies in the EOPs. These were to:
(1) provide for continuous monitoring of key sump performance indicators to ensure transfer to procedure ECA 1.1 (Loss of Emergency Coolant Recirculation) on indications of pump cavitation due to debris blockage of the sump - ICM category #1; and (2) streamline procedure ECA 1.1 instructions to identify debris blockage as the reason for the loss of recirculation, and to prioritize sources of alternate core cooling - ICM category #1.
In your October 29, 2004, response you stated that you had implemented the EOP changes with appropriate training before March 31, 2004, having modified EOPs ES 1.3 Transfer to Cold Leg Recirculation, and ECA 1.1. You stated that you had performed plant simulator validation runs with multiple operator teams to simulate a loss of sump recirculation after a LOCA, exercising the recent EOP changes and demonstrating a consistent level of response from control room operators - ICM category #1.
In your October 29, 2004, response you further stated that subsequent to the implementation of these SPS EOP changes, in March 2004, the Westinghouse Owners Group (WOG) published WCAP-16204, Evaluation of Potential ERG and EPG Changes to Address NRC Bulletin 2003-01 Recommendations (PA-SEE-0085), Revision 1, and that the WOG recommendation was to implement a Westinghouse-specific Sump Blockage Control Room Guideline (SBCRG) from WCAP-16204 Volume II as an interim compensatory action to reduce the potential risk associated with sump blockage. You stated that the SBCRG, as a generic procedure outside of the ERG network of procedures, identified seven major actions to be performed in response to loss of a sump recirculation in a Westinghouse plant with a large dry containment (protect ECCS and CSS pumps, establish and maintain optimum emergency coolant flow, increase/conserve RWST level, initiate cooldown to cold shutdown, depressurize the reactor coolant system (RCS) to minimize RCS subcooling, depressurize steam generators to cool down and depressurize the RCS, and maintain RCS heat removal). You have reviewed the SBCRG and concluded that the March 2004, SPS plant-specific EOP changes addressed the issues covered by the SBCRG, and that no additional compensatory measures related to EOPs were being implemented at SPS.
In a May 17, 2005, response to a March 31, 2005, supplemental RAI you noted at the outset that the SPS has a large, dry sub-atmospheric containment design with ECCS and containment heat removal systems that are specific to that kind of containment, and therefore, there are several non-trivial system differences compared to the Westinghouse reference plant that was used for the evaluations in Volume I of WCAP-16204, Revision 1.
In Table 1 of your May 17, 2005, response you summarized the Dominion evaluation of each candidate operator Action (COA) from Volume 1 of WCAP-16204, Revision 1 as follows:
Mr. Hertz 4 (1) COA A1a, Operator Action to Secure One Spray Pump, would not be implemented at SPS because the SPS containment fan coolers are non-safety related components located in the basement of the containment and would be flooded as the containment fills with water during a LOCA, and because continuous operation of the containment spray system is credited in the radiological analysis for the design basis LOCA (and failure of the running pump could result in a significant increase in offsite dose while providing no appreciable delay in transfer to recirculation);
(2) COA A1b, Operator Action to Secure Both Spray Pumps, would not be implemented at SPS because the SPS containment fan coolers are non-safety related components located in the basement of the containment and would be flooded as the containment fills with water during a LOCA, and because continuous operation of the CSS is credited in the radiological analysis for the design basis LOCA.
(3) COA A2, Manually Establish One Train of Containment Sump Recirculation Prior to Automatic Actuation, would not be implemented because the low head safety injection (LHSI) pump net-positive suction head (NPSH) margin was considered too small to support early switchover to sump recirculation; (4) COA A3, Terminate One Train of Safety Injection After Recirculation Alignment, would not be implemented because a failure of the running pump could result in a significant increase in peak cladding temperature and increase the radiological dose to the public from a LOCA event; (5) COA A4, Early Termination of One LPSI/RHR Pump Prior to Recirculation Alignment, would not be implemented because this action could increase the probability of interrupting all safety injection flow; (6) COA A5, Refill of Refueling Water Storage Tank, had already been implemented since the SPS EOPs include guidance to refill the RWST using borated sources - ICM category #3; (7) COA A6, Inject More Than One RWST Volume From a Refilled RWST or By Bypassing the RWST, had already been implemented in that the SPS EOPs and Severe Accident Management Guidelines (SAMGs) include operator guidance for using the opposite unit RWST as an alternate supply of core cooling (after the beyond design basis condition of complete loss of recirculation) - ICM category #3; (8) COA A7, Provide More Aggressive Cooldown and Depressurization Following a Small Break LOCA, had already been implemented in that the SPS EOPs, which are consistent with the WOG ERGs, include guidance for aggressive cooldown and depressurization - ICM category #2.
(9) COA A8, Provide Guidance on Symptoms and Identification of Containment Sump Blockage, had already been implemented in the SPS EOPs based on the changes completed in March 2004, which provided operators with multiple diverse indicators of containment sump blockage, and related operator training addressed symptoms and identification of sump blockage - ICM category #1; (10) COA A9, Develop Contingency Actions in response to Containment Sump Blockage, Loss of Suction, and Cavitation, had already been implemented in the SPS EOPs based on the changes completed in March 2004, which included the seven major actions outlined in the
Mr. Hertz 5 SBCRG, and simulator scenarios of a loss of recirculation capability due to sump blockage were conducted with multiple operator teams to confirm the validity and efficacy of the EOP changes - ICM category #1; (11) COA A10, Early Termination of One Train of HPSI/High-head Injection Prior to Recirculation Alignment, was not implemented since it was applicable to CE design plants, unlike SPSs Westinghouse design; (12) COA A11, Prevent or Delay Containment Spray for Small Break LOCAs in Ice Condenser Plants, was not applicable to SPS which has a large dry containment.
In an August 26, 2005, letter in response to a July 13, 2005, conference call with NRC staff, you stated that for COA A5, Refill of Refueling Water Storage Tank, Surry EOPs direct cross connection to the non-faulted units RWST upon the event of emergency sump blockage, with refill of the faulted units RWST initiated when the faulted units RWST is being used for injection - ICM category #3.
The NRC staff has considered your Option 2 response for compensatory measures that were or were to have been implemented to reduce the interim risk associated with potentially degraded or nonconforming ECCS and CSS recirculation functions. Based on your response, the NRC staff considers your actions to be responsive to and meet the intent of Bulletin 2003-01. Please retain any records of your actions in response to Bulletin 2003-01, as the NRC staff may conduct subsequent inspection activities regarding this issue.
Should you have any questions, please contact me at 301-415-[xxxx] or the lead PM for this issue, Alan Wang at 301-415-1445.
Sincerely,
[Name], Project Manager, Section [1 or 2]
Project Directorate [I, II, III, or IV]
Division of Licensing Project Management Office of Nuclear Reactor Regulation cc: See next page [Plant Mailing List]
ADD TO DISTRIBUTION: AWang, RArchitzel, DSolorio, MKowal, LWhitney, THafera