ML080230112
| ML080230112 | |
| Person / Time | |
|---|---|
| Issue date: | 03/28/2008 |
| From: | Ruland W NRC/NRR/ADES/DSS |
| To: | Pietrangelo A Nuclear Energy Institute |
| Scott M L, NRR/DSS/SSIB, 415-0565 | |
| Shared Package | |
| ML080230234 | List: |
| References | |
| GL-04-002 | |
| Download: ML080230112 (3) | |
Text
March 28, 2008 Mr. Anthony R. Pietrangelo Nuclear Energy Institute 1776 I Street, NW, Suite 400 Washington DC, 20006-3708
SUBJECT:
REVISED GUIDANCE FOR REVIEW OF FINAL LICENSEE RESPONSES TO GENERIC LETTER 2004-02, POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY RECIRCULATION DURING DESIGN BASIS ACCIDENTS AT PRESSURIZED-WATER REACTORS
Dear Mr. Pietrangelo:
By letter dated September 27, 2007 (ADAMS Accession No. ML072600425), the U.S. Nuclear Regulatory Commission (NRC) staff provided you draft guidance for the staffs review of licensee responses to Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation during Design Basis Accidents at Pressurized-Water Reactors. The review guidance addresses the areas of chemical effects, coatings, and head loss testing. The letter noted that the review guidance is primarily intended for the use of the NRC staff, but that it should also help licensees ensure their final responses to GL 2004-02 are adequate to support closure of GL 2004-02 for their plants. As with any guidance, its use by licensees is not mandatory. Alternate approaches may be used if adequately supported and the NRCs regulations are met.
The September 27, 2007, letter solicited comments on the draft review guidance. The subject was discussed in a public meeting with the Nuclear Energy Institute and other stakeholders on October 24, 2007. In finalizing the review guidance, the staff has considered comments provided verbally at the October 24 meeting. No written comments were received.
This letter transmits the final review guidance. Changes from the draft guidance are indicated in the enclosures through use of sidebars. In general, changes from the draft guidance are minor.
However, new information obtained since the draft guidance was issued has resulted in some changes to Enclosure 1, Guidance for Strainer Head Loss and Vortexing. Specifically, recently obtained test results and test observations indicate that: (1) strainer head loss during testing is very sensitive to debris introduction sequence and assumptions about debris composition, and (2) head losses from a thin bed of debris in a conservative test can be significant.
In revising the guidance, the NRC staff is aware that many plants have completed head loss testing. Head loss testing information was presented in many licensee responses to GL 2004-02, which the staff received in February and March 2008. In addition, many licensees are expected to submit a further response when remaining corrective actions for Generic Letter 2004-02 are complete.
The staff will review licensee responses already received as well as future responses in light of the new information further discussed in Enclosure 1. The staff will consider whether each plants head loss testing supports a holistic conclusion of reasonable assurance of compliance with applicable regulations. Where such assurance has not yet been obtained, the staff plans to seek additional information from affected licensees.
If you would like to discuss the contents of this letter further, please contact me at (301) 415-3283.
Sincerely,
/RA/
William H. Ruland, Director Division of Safety Systems Office of Nuclear Reactor Regulation
Enclosures:
- 1. Review Guidance for Strainer Head Loss and Vortexing
- 2. Review Guidance for Coatings
- 3. Review Guidance for Chemical Effects
The staff will review licensee responses already received as well as future responses in light of the new information further discussed in Enclosure 1. The staff will consider whether each plants head loss testing supports a holistic conclusion of reasonable assurance of compliance with applicable regulations. Where such assurance has not yet been obtained, the staff plans to seek additional information from affected licensees.
If you would like to discuss the contents of this letter further, please contact me at (301) 415-3283.
Sincerely,
/RA/
William H. Ruland, Director Division of Safety Systems Office of Nuclear Reactor Regulation
Enclosures:
- 1. Review Guidance for Strainer Head Loss and Vortexing
- 2. Review Guidance for Coatings
- 3. Review Guidance for Chemical Effects DISTRIBUTION:
Y020070008 PUBLIC DSS r/f WRuland, NRR AHiser, NRR JWermiel, NRR MEvans, NRR MScott, NRR WBateman, NRR DBessette, ACRS RArchitzel, NRR JGolla, NRR LWhitney, NRR RTorres, NRR JLehning, NRR SSmith, NRR PKlein, NRR EGeiger, NRR TCollins, NRR MYoder, NRR Package:
ML080230234 Letter:
ML080230112 : ML080230038 : ML080230462 : ML080380214
- See previous concurrence NRR-106 OFFICE NRR/DSS/SSIB: BC NRR/DCI: D NRR/DSS: D NAME MScott MEvans WRuland DATE 03/03/08 03/05/08 03/28/08 OFFICIAL RECORD COPY