ML023500029
| ML023500029 | |
| Person / Time | |
|---|---|
| Issue date: | 12/13/2002 |
| From: | Beckner W NRC/NRR/DRIP/RORP |
| To: | Pietrangelo A Nuclear Energy Institute |
| Kavanagh K 301-415-3743 | |
| References | |
| Download: ML023500029 (6) | |
Text
December 13, 2002 Mr. Anthony Pietrangelo Nuclear Energy Institute 1776 I Street, N. W.
Suite 400 Washington, DC 20006-3708
Dear Mr. Pietrangelo:
The Nuclear Regulatory Commission (NRC) has completed its review of the Nuclear Energy Institute Technical Specification Change Traveler, TSTF-372, Revision 1, Addition of LCO 3.0.8, Inoperability of Snubbers. TSTF-372 Revision 1 proposed changes to NUREGs-1430, -1431, -1432, -1433, and -1434, Revision 2, Standard Technical Specifications.
Snubbers are designed to prevent unrestricted pipe motion under dynamic loads that might occur during an earthquake or severe transient while allowing normal thermal movement during startup and shutdown. The consequence of an inoperable snubber is an increase in the probability of structural damage to piping resulting from a seismic or other postulated event which initiates dynamic loads. The original NRC staff safety evaluation allowed a period of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for repair or replacement of defective units before the reactor must be shut down.
Since then, the technical specification requirements for snubbers were relocated from the standard technical specifications to the Technical Requirements Manual because the snubber requirements did not meet the criteria of 10 CFR 50.36.
TSTF-372 Revision 1 proposed to add a new LCO 3.0.8 to Section 3.0, LCO and SR Applicability. The proposed LCO would allow a delay time for snubbers which cannot perform their required support function, before the supported systems are declared inoperable. The staff reviewed TSTF-372 Revision 1 and determined that the technical justification did not meet our expectations for the current risk-informed regulatory environment.
In order to address this concern, the TSTF provided a draft copy of TSTF-372 Revision 2 on August 7, 2002, as stated in the NRC summary of the September 23 and 25, 2002, NRC/Industry Meeting of the Risk-Informed Technical Specification Task Force (RITSTF),
dated October 7, 2002, (ADAMS Accession Number ML022810155). The technical justification for draft TSTF-372 Revision 2 provided a simplified risk assessment for snubbers that affect one train while acknowledging that the proposed LCO 3.0.8 should be considered with respect to other plant maintenance activities, and integrated into the existing 10 CFR 50.65(a)(4) process. However, the proposed wording of LCO 3.0.8 provided in draft TSTF-372 Revision 2 would permit removal of snubbers in any combination.
We are sensitive to the need for appropriate completion times for repair or planned maintenance of certain snubbers that affect more than one train. For example, the discovery of a failed snubber should not place the plant in a shutdown sequence. However, the proposed wording of the LCO 3.0.8 is too broad. Further, our experience in working with the TSTF to develop the generic bounding seismic risk analysis for one-train impact leads us to believe that licensees in general may not be capable of performing a meaningful seismic risk assessment.
Mr. A. Pietrangelo December 13, 2002 Since the current 50.65(a)(4) industry guidance does not address seismic risk, we cannot rely on the 50.65(a)(4) process to adequately address the inoperability of snubbers that affect more than one train.
We have modified the proposed LCO to address snubbers that affect single and multiple trains.
We expect that licensees will adopt the generic one-train allowance, and submit plant-specific analysis for any multiple train configurations they want to justify. If a detailed plant-specific seismic risk analysis is not available, an acceptable assumption for a simple bounding analysis is to assume loss of offsite power and the loss of all affected trains and systems.
Draft TSTF-372 Revision 2 LCO 3.0.8 wording also addressed seismic restraints and supports.
We have concluded that LCO 3.0.8 should not contain seismic restraints or supports other than snubbers. The staff has determined that adequate guidance exists in NRC Bulletins 79-02, Revisions 0, 1, and 2, and Supplement 1 to Revision 1; 79-14, Revisions 0 and 1, and Supplements 1 and 2 to Revision 1; and Generic Letter 91-18, Revision 1 dated October 8, 1997. This precedence is documented in a letter dated February 20, 1992 to Northeast Nuclear Energy Company. The TSTF can evaluate this precedent and justify the need for a change, if appropriate.
Please contact me at (301) 415-1161 or e-mail wdb@nrc.gov if you have any questions or need further information on these proposed changes.
Sincerely,
/RA/
William D. Beckner, Program Director Operating Reactor Improvements Program Division of Regulatory Improvement Programs Office of Nuclear Reactor Regulation
Enclosure:
As stated cc:
T. Silko, BWROG D. Bice, CEOG P. Infanger, BWOG S. Wideman, WOG D. Hoffman, EXCEL B. Mann, EXCEL
ML023500029 DOCUMENT NAME: G:\\RORP\\KAVANAGH\\TSTF-372 R1 TSS words OFFICE TSS:RORP:DRIP TSS:RORP:DRIP SC:RORP:DRIP DE/EMEB PD:RORP:DRIP NAME KAKavanagh*
LAHill*
RLDennig*
EVImbro WDBeckner DATE 12/ 2/2002 12/2/2002 12/7/2002 12/13/2002 12/13/2002
Proposed Wording for TSTF-372 Revision 2 LCO 3.0.8 When one or more required snubbers are inoperable, the LCO for each affected supported system is not required to be declared not met for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if risk is assessed and managed, and a.
the inoperable snubbers are associated with one required train for each affected supported systems, and each redundant required train is OPERABLE; or
- b.
[the unit is in a MODE and configuration in accordance with Table XXX].
Otherwise, the LCO for the each associated supported system shall be declared not met.
A reviewers note in the Bases:
[For the purposes of the 10 CFR 50.65(a)(4) analysis of maintenance configurations involving inoperable snubbers, an acceptable assumption for a simple bounding analysis is to assume loss of offsite power and the loss of all affected trains and systems, if a detailed seismic risk analysis is not available. All snubbers that affect the operability of more than one train of a single system shall be identified. LCO 3.0.8 is not applicable to other seismic restraints or supports. The staff has determined that adequate guidance exists in NRC Bulletins 79-02, Revisions 0, 1, and 2, and Supplement 1 to Revision 1; 79-14, Revisions 0 and 1, and Supplements 1 and 2 to Revision 1; and Generic Letter 91-18, Revision 1 dated October 8, 1997 for these other types of restraints and supports. This precedence is documented in a letter dated February 20, 1992 to Northeast Nuclear Energy Company.]
Enclosure