ML050630569

Unit 2 - Closeout Letter for Bulletin 2003-01, Potential Impact of Debris Blockage on Emergency Sump Recirculation at Pressurized-Water Reactors.

ML050630569
Person / Time
Site:	Byron, Braidwood
Issue date:	08/08/2005
From:	Dave Solorio Plant Systems Branch
To:	Suh G NRC/NRR/DLPM/LPD3
Whitney, L.E., NRR/DSSA/SPLB, 415-3081
References
BL-03-001, TAC MB9558, TAC MB9559, TAC MB9560, TAC MB9561
Download: ML050630569 (7)

Text

August 8, 2005 MEMORANDUM TO: Gene Suh, Section Chief, LPDIII-2 Project Directorate III 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:

BYRON, UNIT 1 AND UNIT 2 - 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 the Byron, Unit 1 and Unit 2, and Braidwood, Unit 1 and Unit 2. SPLB has determined that the licensees actions have been responsive to and meet the intent of Bulletin 2003-01. The attachment to this letter provides input to be used in a formal closeout letter to the licensee. 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: 50-454, 50-455, 50-456, 50-457

Attachment:

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

ML050630569 NRR-106 OFFICE DSSA/SPLB DSSA/SPLB DLPM/PDIV-2/PM NAME LWhitney DSolorio AWang DATE 07/ 26 /2005 07/ 29 /2005 08/ 08 /2005 AmerGen Energy Company, LLC 200 Exelon Way Kennett Square, PA19348

SUBJECT:

BYRON STATION UNITS 1 AND 2/BRAIDWOOD STATION UNITS 1 AND 2 -

RESPONSE TO NRC BULLETIN 2003-01, POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY SUMP RECIRCULATION AT PRESSURIZED WATER REACTORS (TAC NOS. MB9560, MB9561, MB9558, AND MB9559)

Dear Mr. Gallegher:

This letter acknowledges receipt of your response dated August 6, 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 reactor water storage tank (RWST) or to otherwise provide inventory to inject into the reactor core and spray into the containment atmosphere; (4) more aggressive containment cleaning and increased foreign material controls; ATTACHMENT

Mr. Gallegher 2 (5) ensuring containment drainage paths are unblocked; (6) ensuring sump screens are free of adverse gaps and breaches.

You stated in your August 6, 2003,Bulletin 2003-01 response that the thermal insulation used on the reactor coolant piping and on the exterior of the reactor vessel is reflective metal insulation (RMI), and that at Braidwood and Byron two ECCS sumps each serve one train of the ECCS and containment spray system. You further stated that you would be implementing the following ICMs:

(1) operator training on indications of and responses to sump clogging, including simulator training on steps to delay RWST depletion - ICM category #1 and ICM category #2; (2) more aggressive containment cleaning and foreign materials control, including specific references to potential debris sources in the containment loose debris inspection procedures, and revisions to containment access procedures to ensure consistent implementation of the loose debris inspection procedure - ICM category #4; and (3) ensuring containment drainage paths are unblocked, including the addition of two inside missile barrier (IMB) access openings and their screen doors at containment elevation 377 feet to the containment loose debris inspection procedure - ICM category #5.

You also stated in your response that you would not be implementing the following as ICMs, because they had already been implemented on a permanent basis:

(1) ensuring sump screens are free of gaps and breaches - ICM category #6; and (2) ensuring that alternative water sources are available to refill the RWST or to otherwise provide inventory to inject into the core and spray into the containment atmosphere - ICM catagory #3.

In your Bulletin response you further stated that:

(1) to reduce the potential for latent debris inside containment, procedures would be enhanced to include specific references to debris sources and make loose debris inspection an integral aspect of containment access - ICM cateory #4; and (2) that it would be inappropriate to implement the suggested practice of delaying the initialtion of cold leg recirculation by reducing ECCS flow during the injection phase of design basis events, but that Byron and Braidwood would monitor Westinghouse Owners Group (WOG) activities to address ECCS sump blockage and would consider implementation of any issued guidance.

In March 2004, the WOG issued WCAP-16204, Revision1, Evaluation of Potential ERG and EPG Charges to Address NRC Bulletin 2003-01 Recommendation (PA-SEE-0085).

Mr. Gallegher 3 In a July 15, 2004, response to a May 4, 2004, NRC request for additional information (RAI),

and a July 8, 2004 correction to that NRC RAI, you stated that you would be implementing the following WOG candidate operator actions (COAs) from WCAP-16204:

(1) COA5 - refill of RWST after switchover to containment sump recirculation (by June 30, 2005) - ICM category #3 (2) COA 6 - pending evaluation of the impact of higher water levels inside the containment, injection of more than one RWST volume from a refilled RWST or by bypassing the RWST (by June 30, 2005) - ICM category #3; (3) COA 7 - provision of more aggressive cooldown and depressurization following a small break LOCA through procedure changes and operator training to emphasize the need to provide a rapid cooldown (by January 31, 2005) - ICM category #2; (4) COA 8 - provision of guidance on symptoms and identification of containment sump blockage with enhanced use of containment sump level indications, predicated on evaluation of whether on the water level indication from in-sump instrumentation can be expected to be accurate and reliable in post-accident situations (by June 30, 2005) - ICM category #1; and (5) COA 9 - development of contingency actions in response to containment sump blockage, loss of suction and cavitation through implementation of the new WOG Sump Blockage Control Room Guideline (SBCRG) (by June 30, 2005) - ICM category #1.

In your July 15, 2004, RAI response you further stated, with justifications, that you would not be implementing the following WOG COAs:

(1) COA 1A - secure one containment spray pump prior to initiating containment sump recirculation (securing one containment spray pump will have virtually no effect on delaying switchover to containment sump recirculation in a large-break LOCA, and for a small break LOCA, reactor coolant system pressure may be above residual heat removal pump shutoff head, containment pressure may not exceed the core spray actuation setpoint of 20 psig, and therefore the low volume centrifugal charging pumps and safety injection pumps would draw so little upon the RWST that the time to switchover on RWST low level would by necessity be significantly increased).

(2) COA 1B - secure both containment spray pumps prior to initiating containment sump recirculation (containment spray pumps are required for iodine removal and pH control);

(3) COA 2 - manually establish one train of containment sump recirculation prior to automatic actuation (debris accumulation at the ECCS sump screens may increase because debris present in the LOCA water would have less time to settle to the containment floor before recirculation flow from the ECCS sump begins);

(4) COA 3 - terminate one train of the ECCS system after recirculation alignment (significant blockage unlikely at this RMI plant);

Mr. Gallegher 4 (5) COA 4 - early termination of one RHR pump prior to recirculation alignment (CE plants only, unlike Byron/Braidwood Westinghouse design);

(6) COA 10 - early termination of one train of HPSI/high head injection prior to recirculation alignment (CE plants only, unlike Byron/Braidwood Westinghouse design); and (7) COA 11 - prevent or delay containment spray for small-break LOCAs in ice condenser plants (Byron and Braidwood have non-ice condenser design containments).

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