ML070080185
| ML070080185 | |
| Person / Time | |
|---|---|
| Site: | Boiling Water Reactor Owners Group |
| Issue date: | 01/24/2007 |
| From: | Ho Nieh NRC/NRR/ADRA/DPR |
| To: | Bunt R BWR Owners Group, Southern Nuclear Operating Co |
| honcharik, M C, NRR/DPR, 415-1774 | |
| References | |
| NEDC-0000-0034-6043, RG-1.174, RG-1.177, TAC MD2837 | |
| Download: ML070080185 (5) | |
Text
January 24, 2007 Mr. Randy C. Bunt Chair, BWR Owners Group Southern Nuclear Operating Company 40 Inverness Center Parkway/Bin B057 Birmingham, AL 35242
SUBJECT:
REQUEST FOR THE REVIEW OF THE BOILING WATER REACTOR (BWR) OWNERS GROUP (BWROG) TOPICAL REPORT (TR)
NEDC-0000-0034-6043, "TECHNICAL JUSTIFICATION TO SUPPORT RISK-INFORMED COMPLETION TIME EXTENSIONS FOR THE STANDBY GAS TREATMENT (SGT) SYSTEM AND MAIN CONTROL ROOM ENVIRONMENTAL CONTROL (MCREC) SYSTEM FOR BWR PLANTS" (TAC NO. MD2837)
Dear Mr. Bunt:
By letter dated July 26, 2006, the BWROG submitted topical report (TR)
NEDC-0000-0034-6043, "Technical Justification to Support Risk-Informed Completion Time Extensions for the Standby Gas Treatment (SGT) System and Main Control Room Environmental Control (MCREC) System for BWR Plants," to the U.S. Nuclear Regulatory Commission (NRC) staff for review.
As we notified you on November 21, 2006, we have completed our acceptance review of your application and all of the supporting information in accordance with the TR Program criteria and have concluded that the TR is not acceptable for review for the reasons discussed below.
TR NEDC-0000-0034-6043 was submitted in connection with the Risk-Informed Technical Specification Task Force Initiative 4a. TR NEDC-0000-0034-6043 provided the results of the application of a risk-informed analysis to identify improvements in completion times (CTs) specified for the SGT and MCREC Systems in the BWR Technical Specifications (TSs).
Regulatory Guide (RG) 1.174, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis, and RG 1.177, An Approach for Plant-Specific Risk-Informed Decisionmaking: Technical Specifications, provide applicable guidance for risk-informed submittals for proposed changes to TSs. RG 1.174 identifies five key principles which proposed changes are expected to meet and RG 1.177 provides additional guidance for these key principles applicable to proposed changes to TSs.
Two of the five key principles are consistency with the defense-in-depth philosophy and maintenance of sufficient safety margins. These deterministic principles are intended to be supplemented with risk insights, which is a separate key principle of RG 1.174.
Our review of TR NEDC-0000-0034-6043 found that it inadequately addressed defense-in-depth and safety margins. Regarding safety margins, a single sentence is provided which states that these margins are not reduced, with no basis provided to justify the statement other than reiterating the risk benefit of avoiding a plant shutdown. Regarding defense-in-depth, the TR identifies that the function of the systems are not relevant to severe
R. C. Bunt accidents, and, therefore, are not significant risk contributors. Therefore, the TR attempts to satisfy these two key deterministic principles based on having acceptably low risk. As noted above, such risk insights are part of a separate key principle and cannot be applied as a basis for satisfying the separate deterministic principles.
The NRC staff also noted additional items which need to be addressed should the BWROG choose to submit a revised TR. Although these additional items would not prevent the NRC staff from accepting the TR for review, the NRC staff would issue them as requests for additional information, should the TR be accepted for review.
TR NEDC-0000-0034-6043 applies the same risk metrics for radiological releases as were used in a cited precedent for conditions involving a loss of function due to emergent failures. As stated in the precedent, these metrics cannot be generalized and used for other applications, such as for routine maintenance activities under the TSs and extending the CT.
TR NEDC-0000-0034-6043 identifies an assumption that the purpose of the action is to complete short duration repairs, but the proposed changes involve a 30-day allowed outage time (AOT). Beyond a survey of plant owners, no basis is provided which justifies the need for this extended AOT.
The MCREC System is evaluated solely in terms of the systems' potential to cause a radiological release; however, the safety function of maintaining a habitable environment for the control room operators during design-basis accident conditions is not evaluated.
Similarly, the equipment cooling function of portions of the system is identified but not further discussed.
TR NEDC-0000-0034-6043 assumes two separate values of a plant core damage frequency (CDF) as its input and calculates the applicable risk metrics. There is no discussion of external events or internal fires risk, which the NRC staff infers are assumed to be included in the CDF. Each plant would need to determine which CDF value was applicable using its plant-specific probabilistic risk assessment (PRA). There is no discussion as to plant-specific PRA quality, scope, or technical adequacy requirements for a licensee implementing the proposed TS changes which would justify that the plant-specific PRA is acceptable to justify that the calculated CDF is bounded by the TR. Since many BWRs do not have full scope PRAs, each individual licensee would be required to justify the out of scope elements which are not addressed by the TR.
These plant-specific issues of PRA scope and quality reduce the regulatory efficiency basis for reviewing and approving generic TRs.
The risk calculations do not distinguish between planned and unplanned maintenance as recommended in RG 1.177.
R. C. Bunt Your request for the review of TR NEDC-0000-0034-6043, "Technical Justification to Support Risk-Informed Completion Time Extensions for the Standby Gas Treatment (SGT) System and Main Control Room Environmental Control (MCREC) System for BWR Plants" is denied, because it inadequately addressed defense-in-depth and safety margins. This does not preclude you from addressing the deficiencies discussed above and resubmitting the TR at a future date.
Sincerely,
/RA/
Ho K. Nieh, Deputy Director Division of Policy and Rulemaking Office of Nuclear Reactor Regulation Project No. 691 cc: See next page
R. C. Bunt Your request for the review of TR NEDC-0000-0034-6043, "Technical Justification to Support Risk-Informed Completion Time Extensions for the Standby Gas Treatment (SGT) System and Main Control Room Environmental Control (MCREC) System for BWR Plants," is denied, because it inadequately addressed defense-in-depth and safety margins. This does not preclude you from addressing the deficiencies discussed above and resubmitting the TR at a future date.
Sincerely,
/RA/
Ho K. Nieh, Deputy Director Division of Policy and Rulemaking Office of Nuclear Reactor Regulation Project No. 691 cc: See next page DISTRIBUTION:
PUBLIC PSPB Reading File RidsNrrDpr RidsNrrDprPspb RidsNrrPMMHoncharik RidsNrrLADBaxley RidsOgcMailCenter RidsAcrsAcnwMailCenter Theodore Robert Tjader Andrew Howe Steven Laur Ravi Grover Chang Li John Segala ADAMS ACCESSION NO.: ML070080185 NRR-106
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SRosenberg HNieh DATE 1/16/07 1/12/07 11/9/06 1/16/07 1/24/07 OFFICIAL RECORD COPY
BWR Owners Group Project No. 691 Mr. Doug Coleman Vice Chair, BWR Owners Group Energy Northwest Columbia Generating Station Mail Drp PE20 P.O. Box 968 Richland, WA 99352-0968 Mr. Amir Shahkarami Executive Chair, BWR Owners Group Exelon Generation Co., LLC Cornerstone II at Cantera 4300 Winfield Road Warrenville, IL 60555 Mr. Richard Libra Executive Vice Chair, BWR Owners Group DTE Energy - Fermi 2 M/C 280 OBA 6400 North Dixie Highway Newport, MI 48166 Mr. William A. Eaton Entergy Operations Inc.
P.O. Box 31995 Jackson, MS 39286 Mr. Richard Anderson First Energy Nuclear Operating Co Perry Nuclear Power Plant 10 Center Road Perry, OH 44081 Mr. Scott Oxenford Energy Northwest Columbia Generating Station Mail Drp PE04 P.O. Box 968 Richland, WA 99352-0968 Mr. James F. Klapproth GE Energy M/C A-16 3901 Castle Hayne Road Wilmington, NC 28401 Mr. Joseph E. Conen Regulatory Response Group Chair BWR Owners Group DTE Energy-Fermi 2 200 TAC 6400 N. Dixie Highway Newport, MI 48166 Mr. J. A. Gray, Jr.
Regulatory Response Group Vice-Chair BWR Owners Group Entergy Nuclear Northeast 440 Hamilton Avenue Mail Stop 12C White Plains, NY 10601-5029 Mr. Thomas G. Hurst GE Energy M/C A-16 3901 Castle Hayne Road Wilmington, NC 28401 Mr. Tim E. Abney GE Energy M/C A-16 3901 Castle Hayne Road Wilmington, NC 28401 BWR Owners Group 7/31/06