ML20207D737
| ML20207D737 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 05/28/1999 |
| From: | Richards S NRC (Affiliation Not Assigned) |
| To: | Cottle W HOUSTON LIGHTING & POWER CO. |
| References | |
| TAC-MA5181, TAC-MA5182, NUDOCS 9906040068 | |
| Download: ML20207D737 (5) | |
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UNITED STATES g
NUCLEAR REGULATORY COMMISSION ~
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WASHINGTON, D.C. 30ee6 0001 May 28, 1999
' Mr. William T. Cottle President and Chief Executive Officer STP Nuclear Operating Company South Texas Project Electric Generating Station P. O. Box 289 Wadsworth,TX 77483
SUBJECT:
SOUTH TEXAS PROJECT, UNITS 1 AND 2 - PROCESS FOR RECLASSlFICATION OF NON-RISK-SIGNIFICANT COMPONENTS (TAC NOS. MA5181 AND MA5182)
Dear Mr. Cottle:
The NRC staff has reviewed your letter dated April 8,1999 (NOC-AE-000506), that described the STP Nuclear Operating Company (STPNOC) approach for reclassifying non-risk-significant components. Your letter outlined a methodology where items determined to be non-risk-significant as part of the graded quality assurance (QA) program would be further evaluated against 10 CFR 50.2 and 10 CFR Part 50, Appendix A, to ascertain whether they could be reclassified as nonsafety-related and not-important-to-safety. Your approach included consideration of 10 CFR 50.59 which defines criteria for when changes to the facility as described in the updated final safety analysis report (UFSAR) need to be submitted to the NRC for approval. ' You requested that the NRC concur with your approach as an acceptable method for meeting regulatory requirements.
The staff cannot determine in advance that your proposal will meet applicable regulatory -
requirements. However, the staff agrees that the approach you describe could conceptually provide a basis for reclassifying equipment and that 10 CFR 50.2 provides the regulatory criteria for determining which plant components are safety related. Based upon a review of the attachment to your letter, which provided some details of the STPNOC reclassification methodology, the staff urges you to use caution in developing and implementing the process to ensure it will meet all applicable regulatory requirements, including 10 CFR 50.2. For example, 10 CFR 50.49(b) defines a set of criteria for determining whether electrical components in a harsh environment are important to safety, and it is not clear from the description provided whether your process would remain in conformance with that regulatory requirement.
We have enclosed a set of some representative concems and cautions for your consideration
- that are based on a limited review of the reclassification process overview that you provided.
Also, the implementation of the reclassification process, and the results, would be subject to NRC inspection as warranted.
The staff agrees that changes to the description of the facility as described in the UFSAR, including the safety classification of components, can be accomplished in accordance with 10 CFR 50.59. If the changes constitute an unreviewed safety question, or if there are changes
. to the technical specifications, then a license amendment application must be submitted to the NRC. The change control processes in 10 CFR 50.54(a) would be applicable only if the
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- description of the component safety classification resided within the QA program. As the c
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j W. T. Cottle May 28, 1999 STPNOC QA program consists of a description of how the requirements of Appendix B to 10 CFR Part 50 are met, the staff believes that in the case of STPNOC, it is not necessary to process changes in component classification in accordance with 10 CFR 50.54(a). It should be noted that the QA programs for other facilities contain an explicit description of component safety classification, so 10 CFR 50.54(a) would then be applicable.
in summary, we concur that you have the ability to amend the safety classification of plant equipment described in the UFSAR provided all the appropriate regulatory requirements are still met. However, STPNOC must structure the implementation specifics of the process to ensure I
- that such conformance is achieved and should carefully consider the example concerns discussed in this letter.
Sincerely, ORIGINAL SIGNED BY S. DEMEK FOR Stuart A. Richards, Director Project Directorate IV & Decommissioning Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-498 and 50-499
Enclosure:
As stated cc w/ encl: See next page.
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e South Texas, Units 1 & 2 cc:
Mr. Comelius F. O'Keefe' Jack R. Newman, Esq.
Senior Resident inspector Morgan, Lewis & Bocklus U.S. Nuclear Regulatory Commission 1800 M Street, N.W.
P. O. Box 910 Washington, DC 20036-5869 Bay City, TX 77414 Mr. J. J. Sheppard A. Ramirez/C. M. Canady Vice President Cityof Austin Engineering & Technical Services Electric Utility Department STP Nuclear Operating Company 721 Barton Springs Road P. O. Box 289 Austin,TX 78704 Wadsworth,TX 77483 Mr. M. T. Hardt Office of the Govemor Mr. W. C. Gunst ATTN: John Howard, Director City Public Service Board Environmental and Natural P. O. Box 1771 Resources Policy San Antonio,TX 78296 P. O. Box 12428 Austin,TX 78711 Mr. G. E. Vaughn/C. A. Johnson Central Power and Light Company Jon C. Wood P. O. Box 289 Matthews & Branscomb MailCode: N5012 One Alamo Center Wadsworth,TX 74483 106 S. St. Mary's Street, Suite 700 San Antonio, TX 78205-3692 INPO Records Center Arthur C. Tate, Director 700 Galleria Parkway Division of Compliance & Inspection Atlanta, GA 30339-3064 Bureau of Radiation Control Texas Department of Health Regional Administrator, Region IV 1100 West 49th Street U.S. Nuclear Regulatory Commisskm Austin,TX 78756 611 Ryan Plaza Drive, Suite 400
- Arlington, TX 76011 Jim Calloway Public Utility Commission of Texas D. G. Tees /R. L. Balcom Electric Industry Analysis Houston Lighting & Power Co.
P. O. Box 13326
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P. O. Box 1700 Austin, TX 78711-3326 Houston,TX 77251
. Judge, Matagorda County Matagorda County Courthouse 1700 Seventh Street -
Bay City, TX 77414 w.
4 s.
NRC Staff Cautions and Concems Reaardina STP Nuclear Operatina Comoanv's (STPNOC's) Reclassification Proposal 1.
There is a concem that STPNOC needs to evaluate, as part of the reclassification process, the potential for simultaneous failure of non-risk-significant (NRS) equipment i
due to a seismic event. For example, the staff believes that the process should consider common-mode effects, such as seismic initiators, on the performance of any safety-related function, including the potential seismic spatial interactions on safety-related equipment.
2.
During discussions with the licensee, the staff expressed a concern that certain American Society of Mechanical Engineers (ASME) Code Class 1 components (less 1
than or equal to 1-inch diameter) that have been designed to ASME Class 2 rules might have their code class changed in conjunction with the licensee's efforts to reclassify components from safety-related to nonsafety-related. STPNOC assured the staff that the ASME code class of components would not be changed as a result of the proposed -
reclassification activities.
3.
Once equipment has been determined by STPNOC to be nonsafety-related, the staff had a question regarding the STPNOC obligation to impose regulatory provisions (such as the Maintenance Rule) to the reclassified items. The staff was informed that STPNOC intends to comply with all regulatory requirements provided the reclassified items remain within the scope of the regulation.
4.
The staff questions how the reclassification process is integrated with the scope of the licensee's ASME Inservice Testing and Inservice inspection Programs based on the Code of Record. The staff was informed that STPNOC intends to maintain ASME code classifications as required by its Code of Record, regardless of whether items are reclassified as NRS.
5.
The staff is concerned that reclassifying a component from important-to-safety to not important-to safety may have the potential to increase the unreliability of safety systems, and increase the possibility for common-mode failures of safety systems, during design-basis events. For example, with respect to the potential reclassification of small drain valves such as the valve located on an emergency diesel generator fuel oil day tank, due to the potential for valve failure when replaced with a lower pedigree valve that is inspected less frequently, there could be an increased probability of leakage of fuel oil which would present an increased flammability hazard and reduce the reliability of a safety system (i.e., the diesel generator). The staff believes that the consequences of this type of failure on the reliability of safety systems should be factored into the reclassification process (or replacement process) for components.
6.
The staff believes STPNOC, as part of its 10 CFR 50.59 evaluation, will need to more explicitly map the NRS and safety-related criteria to the 10 CFR 50.59 unreviewed safety question criteria so that it is clearly defined as to which part of the NRS and safety-related processes is being relied upon to satisfy the criteria.
ENCLOSURE
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2 7.
The licensee should ensure that regulatory commitments associated with components that are reclassified to nonsafety related are controlled as appropriate. For example, the licensee made certain commitrre nts in response to Generic Letters 89-iO and 96-05 to ensure that motor-operated valves (MOVs) v:.:nid be capable of performing their design-basis safety function. This may have included a commitment related to MOVs when they are placed in their nonsafety position (e.g., for maintenance or sunreillance testing).
Such a commitme it might stipulate that these MOVs will be capable of transfernng to their safety positions or that any applicable technical specificatione would be entered when the MOVs are in their nonsafey position.
l 8.
The staff has a question with respect to 10 CFR 50.49(b) which defines electrical equipment in a harsh environment that is important to safety. This definition includes nonsafety-related equipment whose failure under postulated environmental conditions could prevent safety-refated equipment from performing its safety function. In contrast, the STPNOC approach for determining NRS equipment appears to consider only whether the loss of funct!on could directly fail a risk-significant system. The staff understands that within the STPNOC process, safety related is not synonymous with j
risk significant. The STPNOC process would have to continue to comply with all
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regulatory requirements, including 10 CFR 50.49.
9.
The staff is concerned with how the STPNOC process will handle high-energy line break evaluations when equipment is reclassified. The staff was informed that the process will j
ensure that normal design process controls will be instituted so tnat appropriate design criteria (such as the need for snubbers, whip restraints, and jet impingement considerations) are applied to the reclassified items.
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