L-04-004, 11/24/2008 - Summary of Meeting to Discuss 11/21/2008 and 11/18/2008 Requests for Additional Information GL 2004-04, Potential Impact of Debris Blockage of Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors
| ML083310397 | |
| Person / Time | |
|---|---|
| Site: | Mcguire, Catawba, McGuire  |
| Issue date: | 12/03/2008 |
| From: | Thompson J H Plant Licensing Branch II |
| To: | Office of Nuclear Reactor Regulation |
| Thompson Jon, NRR/DORL/LPL 2-1, 415-1119 | |
| References | |
| GL-04-004, TAC MD7718, TAC MD7719, TAC MD7720, TAC MD7721 | |
| Download: ML083310397 (4) | |
Text
December 3, 2008 LICENSEE: DUKE ENERGY CAROLINAS, LLC (DUKE)
FACILITY: CATAWBA NUCLEAR STATION, UNITS 1 AND 2 (CATAWBA) AND MCGUIRE NUCLEAR STATION, UNITS 1 AND 2 (MCGUIRE)
SUBJECT:
SUMMARY
OF NOVEMBER 24, 2008, MEETING TO DISCUSS NOVEMBER 21, 2008, AND NOVEMBER 18, 2008, REQUESTS FOR ADDITIONAL INFORMATION CONCERNING GENERIC LETTER 2004-04, "POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY RECIRCULATION DURING DESIGN BASIS ACCIDENTS AT PRESSURIZED-WATER REACTORS" (TAC NOS. MD7718, MD7719, MD7720 AND MD7721)
On November 24, 2008, a category 1 public meeting was held between the U.S. Nuclear Regulatory Commission (NRC) and representatives of Duke at NRC Headquarters, Two White Flint North, 11545 Rockville Pike, Rockville, Maryland. The purpose of the meeting was to discuss Duke's approach to responding to the subject Requests for Additional Information (RAI). A list of attendees is provided as Enclosure 1. The discussions were held in the context of two NRC staff RAIs dated November 21, 2008 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML083080373) and November 18, 2008 (ADAMS Accession No. ML083080350).
During this meeting Duke presented an overview of the Generic Safety Issue - 191 project team, the strainer design and layout, recent testing, NRC-provided feedback on Duke testing, and high-level conservatisms (see ADAMS Accession No. ML083300061). The NRC staff had several concerns with Duke's test program which it expressed during this presentation including:
- 1) The debris beds for the array testing and Integrated Prototype Test (IPT) appeared to be non-conservative due to the debris preparation and introduction methods used during the testing. More specifically, the NRC staff is concerned that fine fibrous debris, which may be the only debris to reach the strainer under actual plant post-loss-of-coolant accident conditions, was not adequately represented due to inadequate debris preparation resulting in less than the predicted amount of fine fiber being added to the test, and inadequate debris introduction resulting in agglomeration of the fibrous debris into larger clumps. The NRC staff considers fine fibrous debris to be easily suspendible. Larger fibrous debris pieces do not transport as readily as fine pieces and have also been noted to result in lower head losses than fine fiber for equivalent amounts of debris when they reach the strainer. Most early head loss testing was conducted with generically prepared fiber that did not consider specific plants' debris generation and transport calculations.
- 2) It appeared that the IPT testing experienced non-conservative bed formation resulting from flow-induced effects. The bed formed on the test strainer in the IPT was significantly skewed toward the base of the module. A significant portion of the strainer was observed to be clean. The NRC staff has observed top-hats with debris accumulations that are greater at the base, but not to such a significant degree. It Duke appeared that the axially oriented flow approaching the test module helped to prevent debris from accumulating at the open end of the top-hat by sweeping it toward the base of the test module. Although some flow may approach the strainer module axially, the IPT setup resulted in a majority of the flow approaching the open end of the test module.
Some of the modules in the plant array may have a majority of the flow approaching from the open end, but most would not. Since non-prototypically induced clean strainer area would be non-conservative, application of such test results would also be non-conservative.
As a result of the concerns expressed in this meeting, the NRC staff is not certain that Duke will be able to adequately address the NRC staff's RAI questions without performing additional testing which addresses the NRC staff's concerns expressed above.
A member of the public was in attendance. Public Meeting Feedback forms were not received.
Please direct any inquiries to me at 301-415-1119, or jht2@nrc.gov. /RA/ Jon H. Thompson, Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-413, 50-414, 50-369 and 50-370
Enclosure:
List of Attendees cc w/encl: Distribution via Listserv
PKG ML083310428 Meeting Notice: ML083100948 Meeting Summary: ML083310397 Handouts: ML083300061 OFFICE DORL/LPL2-1/PM DORL/LPL2-1/LA DORL/LPL2-1/BC DORL/LPL2-1/PM NAME JThompson MO'Brien MWong (LOlshan for) JStang DATE 12/3/08 12/3/08 12/3/08 12/3/08 LIST OF ATTENDEES NOVEMBER 24, 2008, MEETING WITH DUKE ENERGY CAROLINAS, LLC TO DISCUSS NOVEMBER 21, 2008, AND NOVEMBER 18, 2008, REQUESTS FOR ADDITIONAL INFORMATION CONCERNING GENERIC LETTER 2004-04, "POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY RECIRCULATION DURING DESIGN BASIS ACCIDENTS AT PRESSURIZED-WATER REACTORS" NRC DUKE ENERGY CAROLINAS, LLC J. Stang R. Lytton M. Scott P. Roberson A. Hiser D. Rochester J. Lubinski M. Branham M. Yoder T. Hamilton J. Lehning A. Tuckman M. Wong A. Jackson W. Golumbfskie E. Crabtree E. Wong A. Smith B. Lin R. Hart E. Geiger J. Nolin E. Dickson K. Ashe D. Harrison S. Smith P. Klein L. Whitney J. Thompson
Mitsubishi Nuclear Energy Systems, Inc.
J. Chung Enclosure