ML052500702

Closeout Letter for Bulletin 2003-01, Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized-Water Reactors.

ML052500702
Person / Time
Site:	Calvert Cliffs
Issue date:	09/20/2005
From:	Dave Solorio Plant Systems Branch
To:	Richard Laufer NRC/NRR/DLPM/LPD1
Whitney L, NRR/DSSA/SPLB, 415-3081
References
BL-03-001, TAC MB9620
Download: ML052500702 (8)

Text

September 20, 2005 MEMORANDUM TO: Richard Laufer, Chief, Section 1 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:

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 Calvert Cliffs 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: 50-317, 50-318

Attachment:

As stated CONTACTS: Leon Whitney, SPLB/DSSA 415-3081 Alan B. Wang, DLPM, PD IV 415-1445

September 20, 2005 MEMORANDUM TO: Richard Laufer, Chief, Section 1 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:

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 Calvert Cliffs 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: 50-317, 50-318

Attachment:

As stated CONTACTS: Leon Whitney, SPLB/DSSA 415-3081 Alan B. Wang, DLPM, PD IV 415-1445 DISTRIBUTION:

LWhitney PMilano Awang Accession No.: ML052500702 NRR-106 OFFICE DLPM/PDIV-2/PM DSSA/SPLB DSSA/SPLB NAME AWang LWhitney DSolorio DATE 09/ 20 /05 09/ 09 /05 09/ 08 /05 OFFICIAL RECORD COPY

Constellation Generation Group, LLC 1650 Calvert Cliffs Parkway Lusby, Maryland 20657

SUBJECT:

CALVERT CLIFFS NUCLEAR POWER PLANT UNITS 1 & 2 - RESPONSE TO NRC BULLETIN 2003-01, POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY SUMP RECIRCULATION AT PRESSURIZED WATER REACTORS (TAC NO. MB9620)

Dear Mr. Gallagher:

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 ATTACHEMENT

Mr. Gallagher 2 inject into the reactor core and spray into the containment atmosphere; (4) more aggressive 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.

In your bulletin response of August 8, 2004, you provided the following information:

(1) all sump strainer materials are stainless steel and are therefore able to withstand long-term exposure to a boric acid environment - ICM category #6; (2) containment cleanliness controls already explicitly provide guidance for continuously maintaining the containment clean during shutdown conditions (foreign material controls), and the closeout procedure directs the identification and removal of trash and debris from all areas inside containment (with particular instructions for inspecting and cleaning the lowest level of the containment) - ICM category #4; (3) containment closeout controls require inspection of the containment sump for evidence of structural distress or abnormal corrosion.- ICM category #6; (4) containment coating controls ensure that degraded coatings are identified and repaired and/or replaced - ICM category #4; (5) during containment recirculation operators are trained to monitor high head safety injection pump flow, discharge pressure and amperage for indications of sump blockage, and to take appropriate action such as reducing pump flow rates - ICM category #1; (6) Severe Accident Management Guidelines direct Technical Support Center (TSC) personnel to recommend the establishment of alternate sources of water/flowpath alignments for RCS injection in the event of sump blockage, within containment water level structural limits - ICM category #3; and (7) although containment drains are inspected for debris/blockage, Calvert Cliffs has a conservative net-postitive suction head (NPSH) calculation which assumes that the refueling pool drain and the drain in the reactor pedestal annular area are clogged - ICM category #5.

You also stated in your response that you would consider enhancements to current operator training relative to sump clogging, and that this evaluation would, if applicable, be completed by January 31, 2004.

You further stated in your response, including justifications, that you would not be implementing the following interim compensatory measure: procedural modifications, if appropriate, that would delay the switchover to containment pump recirculation. You stated that you would evaluate all such actions, in collaboration with the Westinghouse Owners Group, to determine if any such actions are beneficial.

In a November 8, 2004, response to a September 10, 2004, NRC request for additional information (RAI), you stated that you had evaluated operator sump clogging responses and determined that a lesson plan and a formal procedure modification were to be created and used to reinforce these existing operator actions, all actions to be completed by June 30, 2005 - ICM category #1.

Mr. Gallagher 3 In your November 8, 2004 RAI response you provided a detailed discussion of your evaluation of Westinghouse Owners Group (WOG) WCAP-16204, Revision 1, Evaluation of Potential ERG and EPG Changes to Address NRC Bulletin 2003-01 Recommendations (PA-SEE-0085) and its 11 applicable candidate operator actions (COA) as follows:

(1) COA 1a, Secure One CS Pump Before Recirculation Alignment: concluding that voluntarily terminating one CS train and then losing the other train via single-failure early in an event would result in so harsh a containment environment that it would adversely affect the qualification of certain pieces of electrical equipment which are required to be operable, and that therefore this COA would not be implemented; (2) COA 1b, Operator Action to Secure Both Spray Pumps, concluding that voluntarily terminating one CS train and then losing the other train via single-failure early in an event would result in so harsh a containment environment that it would adversely affect the qualification of certain pieces of electrical equipment which are required to be operable, and that therefore this COA would not be implemented:

(3) COA 2, Manually Initiate One Train of Containment Sump Recirculation Before a Recirculation Actuation Signal: concluding that timing factors effectively prevent this action during large-break LOCAs, and for small break LOCAs low flow rates due to RCS back-pressure could lead to catastrophic LPSI pump damage, and that therefore this COA would not be implemented; (4) COA 3, Terminate One Train of HPSI Following a Recirculation Actuation Signal:

concluding that this COA results in an unacceptable increase in NPSH requirements over existing procedures, which already require significant throttling of both HPSI pumps, and that therefore this COA would not be implemented; (5) COA 4, Terminate Low Pressure Safety Injection Pump Before Recirculation Actuation Signal, concurring with the WOG WCAP-16204 analysis that this is not a net-benefit action, and that therefore this COA would not be implemented; (6) COA 5, Refill the Refueling Water Tank (RWST): concluding that Calvert Cliffs will modify its emergency operating procedures for a LOCA to include a step instructing that preparations be made to refill the RWST - ICM category #3; (7) COA 6, Inject Into RCS from Refilled RWST, or by Bypassing RWST: concluding that Calvert Cliffs will modify its emergency operating procedures to include steps instructing that preparations be made to allow injection from an alternate source directly into the RCS - ICM category #3; (8) COA 7, Provide More Aggressive Cooldown and Depressurization Following a Small-Break LOCA: concluding that current Calvert Cliffs procedures currently allow for aggressive cooldown within safety limits - ICM category #2; (9) COA 8, Provide Guidance on Symptoms and Identification of Sump Blockage as Well as Contingency Actions to be Taken in the Event of Sump Blockage: concluding that Calvert Cliffs will modify its emergency operating procedures for a LOCA to include a step instructing that the ECCS pumps should be monitored for a loss of suction (CS and HPSI flow, discharge pressure, motor current, and noise) - ICM category #1;

Mr. Gallagher 4 (10) COA 9, Develop Contingency Actions in Response to Containment Sump Blockage, Loss of Suction, and Cavitation: concluding that if any conditions of COA 8 are detected, operators are instructed to secure CS pumps and shift to containment air coolers while monitoring HPSI pumps for indications that flow throttling, or flow stoppage, and shifting to severe accident management guidelines are required - ICM category #1; (11) COA 10, Terminate HPSI Prior to Recirculation Actuation Signal: concluding that Calvert Cliffs concurs with the WOG that unacceptable conditions would result in single-failure situations, and that therefore this COA would not be implemented.

(12) COA 11, Prevent or Delay Containment Spray for Small Break LOCAs (<1.0 Inch Diameter) in Ice Condenser Plants, (not applicable to Calvert Cliffs dry containment design).

In an August 4, 2005, response to questions raised in a July 5, 2005, conference call with the NRC staff, you amplified your responses regarding COA 5, COA 6 and COA 7 as follows:

(1) COA 5, Refill the Refueling Water Tank (RWST): stating that under EOP-05-1 and EOP-08-1 for Unit 1, if there is a recirculation actuation signal, the operators are directed to refill the RWT, and similar information exists for Unit 2 - ICM category #3, (2) COA 6, Inject Into RCS from Refilled RWST, or by Bypassing RWST: stating that under EOP-08-1 the steps exist for accomplishing RWT injection from a refilled RWT - ICM category

1. 3, and (3) COA 7, Provide More Aggressive Cooldown and Depressurization Following a Small-Break LOCA: stating that changes have been made to EOP-05 and EOP-08 basis documents clearly stating that cooldown during a LOCA should be as aggressive as plant conditions allow, and that this change is being incorporated into applicable training programs - ICM category #2.

In an August 30, 2005, response to questions raised in a an August 11, 2005, conference call with the NRC staff you discussed COA 6, Inject Into RCS from Refilled RWST, or by Bypassing RWST as follows: the opposite unit RWT is the alternate source for RWT makeup water (with two such paths for RWT cross-tie refill existing), and the multiple alternate (RWT bypass) injection paths are from the opposite unit RWT (2 paths), the spent fuel pools (2 paths), and the condensate storage tanks - 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-[xxix] or the lead PM for this issue, Alan Wang at 301-415-1445.

Sincerely,

Mr. Gallagher 5

[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