ML110140404
| ML110140404 | |
| Person / Time | |
|---|---|
| Site: | Boiling Water Reactor Owners Group, PROJ0694 |
| Issue date: | 05/13/2011 |
| From: | Bahadur S NRC/NRR/DSS |
| To: | Schiffley F Exelon Generation Co |
| Architzel R, NRC/NRR/DSS/SSIB, 415-2804 | |
| References | |
| GSI-191 | |
| Download: ML110140404 (3) | |
Text
May 13, 2011 Frederick P. "Ted" Schiffley, II BWROG Chairman c/o Exelon Generation Co., LLC Cornerstone II at Cantera 4300 Winfield Road Warrenville, IL 60555
Dear Mr. Schiffley:
The purpose of this letter is to provide feedback to the Boiling Water Reactor Owners Group (BWROG) regarding its program to assess the performance of boiling water reactor (BWR) emergency core cooling system (ECCS) suction strainers in light of lessons learned during the resolution of Generic Safety Issue (GSI) 191, Assessment of Debris Accumulation on PWR
[pressurized water reactor] sump performance.
The BWR licensees and the Nuclear Regulatory Commission (NRC) staff conducted research and developed guidance to resolve the issue of debris blockage of BWR ECCS suction strainers, and BWR licensees made significant hardware and procedure changes in the 1990s.
Research and testing for GSI-191 led to subsequent refinements in the guidance used by PWR licensees for evaluating debris blockage. The NRC staff assessed the differences between the PWR and BWR methodologies and noted that (1) several areas were treated less conservatively for BWRs than PWRs and (2) some areas had not been addressed by BWRs, including the potential for debris to bypass the ECCS suction strainer and block flow to the core
[1]. The BWROG assessed the differences between the BWR and PWR methodologies, and developed a program to evaluate the new information.
The BWROG described the program in letters dated April 13, 2009 [2], July 17, 2009 [3], and August 31, 2010 [4], and discussed the details with the NRC staff in a series of meetings including four in late 2010 [5-8]. In a letter dated January 5, 2011 [9], the BWROG clarified that the program would result in updates to the previous guidance documents and a series of topical reports. The NRC staff is currently reviewing several work products that were developed as part of the BWROG program. The plans show completion of BWR guidance documents in 2015.
The staff has reviewed the BWROGs program as described in the above letters and meeting presentations. The staff concludes that the program is comprehensive in that it addresses all of the identified technical issues. Further, the BWROGs April 13, 2009 [2], letter discusses the modifications made to BWRs in the 1990s, margin considerations regarding the ECCS suction strainer evaluations, and the availability of alternative paths for cooling the reactor in the case of debris blockage. One margin noted by the BWROG was the significant reduction in the amount of debris generated by the more probable, smaller breaks when compared to the large breaks that were assumed in the design of the strainers. Regarding the issue of debris that bypasses the ECCS suction strainer, the BWROG developed a topical report [10], currently under staff review, to show that core cooling will be maintained even if the core inlet is completely blocked by debris.
F. Schiffley Based on the above, the staff considers the overall program scope to be reasonable and the schedule to be generally consistent with the staff requirements memorandum to SECY-10-0113
[11]. Enclosed you will find a list of references.
We look forward to continuing interactions with the BWROG staff on this subject. Please contact Mr. Stewart Bailey (Stewart.Bailey@nrc.gov, 301-415-1321) as necessary to further discuss these matters.
Sincerely,
/RA/
Sher Bahadur, Acting Director Division of Safety Systems Office of Nuclear Reactor Regulation
Enclosure:
As stated
Based on the above, the staff considers the overall program scope to be reasonable and the schedule to be generally consistent with the staff requirements memorandum to SECY-10-0113
[11]. Enclosed you will find a list of references.
We look forward to continuing interactions with the BWROG staff on this subject. Please contact Mr. Stewart Bailey (Stewart.Bailey@nrc.gov, 301-415-1321) as necessary to further discuss these matters.
Sincerely,
/RA/
Sher Bahadur, Acting Director Division of Safety Systems Office of Nuclear Reactor Regulation
Enclosure:
As stated Distribution:
SSmith JBeall RArchitzel EGeiger RidsNrrDssSsib MYoder EWong JGolla RidsNrrDss RidsNrrDciCsgb PUBLIC RidsNrrDprPlpb RidsOgcMailCenter ADAMS Accession Number: ML110140404 NRR-106 OFFICE NRR/DSS/PLPB NRR/DSS/SSIB: BC NRR/DSS: D(A)
NAME JGolla*
SBailey SBahadur DATE 5/12/11 5/13/11 5/13/11
- see previous OFFICIAL RECORD COPY
REFERENCES
[1]
Letter to R. Anderson, BWROG, from J. Grobe, NRC, dated April 10, 2008, Potential Issues Related to Emergency Core Cooling Systems Strainer Performance at Boiling Water Reactors, ML080500540.
[2]
Letter to J. Grobe, NRC, from R. Anderson, BWROG, dated April 13, 2009, Boiling Water Reactor Owners' Group, Potential Issues Related to Emergency Core Cooling Systems Strainer Performance at Boiling Water Reactors, ML092160139
[3]
Letter to J. Grobe, NRC, from R. Anderson, BWROG, dated July 17, 2009, Boiling Water Reactor Owners Group Plans for Addressing NRC Concerns Related to Emergency Core Cooling System (CCS) Strainer Performance At Boiling Water Reactors, ML092010500.
[4]
Letter to J. Golla, NRC, from F. Schiffley II, BWROG, dated August 31, 2010, BWROG ECCS Suction Strainer Issue Resolution Schedule Update, ML102520050.
[5]
Memorandum to M. Scott, NRC, from J. Golla, NRC, dated September 8, 2010, Summary of August 10 & 11, 2010, Public Meeting with the Boiling Water Reactor Owners Group (BWROG), ML102360056.
[6]
Memorandum to S. Bailey, NRC, from J. Golla, NRC, dated October 18, 2010, Summary of September 22, 2010, Public Meeting with the Boiling Water Reactor Owners Group (BWROG), ML102800152.
[7]
Memorandum to S. Bailey, NRC, from J. Golla, NRC, dated November 4, 2010, Summary of October 20, 2010, Public Meeting with the Boiling Water Reactor Owners Group (BWROG), ML103010393.
[8]
Memorandum to S. Bailey, NRC, from J. Golla, NRC, dated February 2, 1011, Summary of November 17, 202, Public Meeting with the Boiling Water Reactor (BWR)
Owners Group (BWORG), ML110110307.
[9]
Letter to J. Golla, NRC, from F. Schiffley II, BWROG, dated January 5, 2011, BWROG ECCS Suction Strainers Action Item No. 15 Status, ML110070027.
[10]
Letter to J. Golla, NRC, from F. Schiffley II, BWROG, dated January 13, 20011, Submittal of Boiling Water Reactor Owners Group (BWROG) Licensing Topical Report, Boiling Water Reactor Emergency Core Cooling Suction Strainer In-Vessel Downstream Effects NEDC-33608P, ML110140479.
[11]
Memorandum to R. Borchardt, NRC, from A. Vietti-Cook, NRC, dated December 23, 2010, Staff Requirements - SECY-10-0113 - Closure Options for Generic Safety Issue - 191, Assessment of Debris Accumulation on Pressurized Water Reactor Sump Performance, ML103570354.
ENCLOSURE
BWR Owners= Group Project No. 691 BWROG Chairman Frederick P. Schiffley Exelon Generation Co., LLC Cornerstone II at Cantera 4300 Winfield Road Warrenville, IL 60555 Frederick.schiffley@exeloncorp.com BWROG Vice Chairman Michael H. Crowthers PPL Susquehanna, LLC 2 North Ninth Street Allentown, PA 18101-1179 mhcrowthers@pplweb.com BWROG Project Manager Robert Whelan GE-Hitachi Nuclear Energy 3901 Castle Hayne Road, M/C F-12 Wilmington, NC, 28402, USA Robert.Whelan@ge.com BWROG Program Manager:
Craig J. Nichols GE-Hitachi Nuclear Energy PO Box 780 M/C F12 3901 Castle Hayne Road Wilmington, NC 28402 craig.nichols@ge.com GEH Senior Vice President:
Jerald G. Head Senior Vice President, Regulatory Affairs GE-Hitachi Nuclear Energy Americas LLC PO Box 780, M/C A-18 Wilmington, NC 28401-0780 Jerald.head@ge.com