ML051890259
| ML051890259 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 07/14/2005 |
| From: | Dave Solorio Plant Systems Branch |
| To: | Darrell Roberts NRC/NRR/DLPM/LPD2 |
| Whitney L, NRR/DSSA/SPLB, 415-3081 | |
| References | |
| BL-03-001 | |
| Download: ML051890259 (7) | |
Text
July 14, 2005 MEMORANDUM TO: Darrell J. Roberts, Section Chief, LPD1-2 Project Directorate I 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:
SEABROOK, UNIT 1 - 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 Seabrook, Unit 1. 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 plant. 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:
50-443
Attachment:
As stated CONTACTS: Leon Whitney, SPLB/DSSA 415-3081 Alan B. Wang, DLPM, PD IV 415-1445
ML051890259 NRR-106 OFFICE DLPM/PDIV-2/PM DSSA/SPLB DSSA/SPLB NAME AWang LWhitney DSolorio DATE 07/ 16 /05 07/ 08 /05 07/ 14 /05
ATTACHMENT FPL Energy Seabrook Station P.O. Box 300 Seabrook, NH 03874
SUBJECT:
SEABROOK UNIT 1 - RESPONSE TO NRC BULLETIN 2003-01, POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY SUMP RECIRCULATION AT PRESSURIZED WATER REACTORS (TAC NO. MB9612)
Dear Mr. Warner:
This letter acknowledges receipt of your response dated August 8, 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 interim compensatory measures 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 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 interim compensatory measures (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
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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 8, 2003, that you had implemented the following interim compensatory measures:
(1) operator guidance and training for continuously monitoring ECCS and containment building spray (CBS) pump parameters, including loss of net-positive suction head (NPSH) as indicated by erratic current, flow, discharge pressure, suction pressure (CBS pumps only), and pump bearing temperature - ICM category #1; (2) for small to medium LOCAs, guidance to delay depletion of the refueling water storage tank (RWST) before switchover to recirculation through cooldown and depressurization of the reactor coolant system (RCS), with sequential stopping of ECCS pumps based on core cooling criteria - ICM category #2; (3) RWST refill, to be accomplished after it is determined that there is a loss of sump recirculation capability using chemical and volume control system (CVCS) blended makeup - ICM category #3; (4) an aggressive containment cleaning and foreign material exclusion program meeting the latest industry guidance of NEI 02-01, Revision 1, Condition Assessment Guidelines; Debris Sources Inside PWR Containments - ICM category #4; (5) the existence of numerous bio-shield openings from the area containing the reactor vessel and RCS piping to the outer containment annulus leading to the sumps, the existence of large stairwell openings in the upper levels of the containment, verified open refueling pool drains, and engineering/design reviews of equipment to be left in containment after outages - ICM category #5; (6) visual inspections of the containment sumps at least once per 18 months for signs of distress or abnormal conditions - ICM category #6.
You also stated in your response that you would be implementing the following interim compensatory measures:
(1) adding operator guidance and training for continuously monitoring ECCS CBS pump parameters in procedures for transferring to cold leg recirculation by October 2003 - ICM category #1; (2) procedural changes to use residual refueling water storage tank (RWST) capacity by lining up the high head safety injection charging pumps to take a suction from the RWST, by October 2003 - ICM category #2; (3) to support debris transport analyses, a walkdown of the containment building recirculation flowpaths in accordance with the guidance of NEI 02-01, Revision 1, Condition Assessment Guidelines; Debris Sources Inside PWR Containments by October 2003 - ICM category #5;
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(4) the addition of more details in the acceptance criteria for inspections of the containment sumps, and application of these enhanced criteria during the October 2003 outage - ICM category #6.
You further stated in your response, including justifications, that you would not be implementing the following interim compensatory measure: for larger LOCAs, procedural changes that would delay the switchover to containment sump recirculation.
In an October 28, 2004, response to a September 10, 2004, NRC request for additional information (RAI) you elaborated on the existing operator actions now included in your revised EOPs. The EOP steps address responses to small, medium and large break LOCAs, transfer to cold leg recirculation, and operator response to sump clogging and loss of ECCS recirculation capability, with new emphasis on shutting down redundant pumps not necessary for core heat removal and containment building cooling/depressurization/iodine removal - ICM category #1 and ICM category #2.
In your October 28, 2004, response you also elaborated on your evaluation of the Westinghouse Owners Group (WOG) Candidate Operator Actions (COAs) of WCAP-16204, Evaluation of Potential ERG and EPG Changes to Address NRC Bulletin 2003-01 Recommendations (PA-SEE-0085), Revision 1 dated March 2004. Your COA evaluation results were as follows:
(1) COA A1a-W Secure One Spray Pump was not appropriate for Seabrook Station due to its non-fan cooler design; (2) COA A1b Operator Action to Secure Both Spray Pumps was not appropriate for Seabrook Station due to its non-fan cooler design; (3) COA A2 Manually Establish One Train of Containment Sump Recirculation Prior to Automatic Actuation was only applicable to small break LOCAs, which for Seabrook will reach cooldown conditions before switchover to recirculation (as discussed for COA A7 below), and therefore will not be implemented; (4) COA A3-W Terminate One Train of Safety Injection after Recirculation Alignment was determined to be non-beneficial due to increased localized flow rates in the vicinity of the remaining independent sump screen; (5) COA A4 Early Termination of One LPSI/RHR Pump Prior to Recirculation Alignment was not applicable to the Seabrook ECCS design with its dependent low and high pressure pumps (CE plant applicability only, unlike Seabrooks Westinghouse design);
(6) COA A5 Refill of Refueling Water Storage Tank was accomplished by refilling the RWST from the chemical and volume control system (CVCS) upon switchover to sump recirculation, and also by drawing a suction on the RWST with the charging pumps (which take suction lower in the RWST thereby drawing upon normally unused RWST capacity) - ICM category #3; (7) COA A6 Inject more than one RWST Volume from a Refilled RWST or by Bypassing the RWST was implemented by refilling the RWST and taking a suction on the RWST with charging pumps (as discussed for COA A5 above), and by aligning the Volume Control Tank
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(VCT) for makeup via the CVCS blended makeup system and charging pumps to the RCS when the charging pumps can no longer take a suction on the RWST (RWST bypass) - ICM category #3; (8) COA A7 Provide More Aggressive Cooldown and Depressurization Following a Small Break LOCA Seabrook procedures, modeled on the Westinghouse Emergency Response Guidelines (ERGs), already address maximizing the cooldown rate up to the Technical Specification limit (see discussion above for small to medium LOCAs) - ICM category #2; (9) COA A8-W Provide Guidance on Symptoms and Identification of Containment Sump Blockage: considered and implemented (see discussion above) - ICM category #1; (10) COA A9-W Develop Contingency Actions in Response to: Containment Sump Blockage, Loss of Suction, and Cavitation: applicable WOG recommended items considered and implemented (see discussion above) - ICM category #1; (11) COA A10 Early Termination of One Train of HPSI/High-Head Injection Prior to Recirculation Alignment (RAS): applicable to CE plants only, unlike Seabrooks Westinghouse design; (12) COA A11 Prevent or Delay Containment Spray for Small Break LOCAs (<1.0 Inch Diameter) in Ice Condenser Plants: Seabrooks dry containment is not equipped with an ice condenser.
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