ML20136H644
| ML20136H644 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 03/14/1997 |
| From: | Baron R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF ADMINISTRATION (ADM) |
| References | |
| FRN-62FR7075 62FR7075-00003, 62FR7075-3, FACA, NUDOCS 9703190226 | |
| Download: ML20136H644 (4) | |
Text
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, :c a c m,3' Tennessee Valley Authority,1101 Market Street, Chattanooga, Tennessee 37402 2801 March 14, 1997 Chief, Rules Review and Directives Branch U.S.
Nuclear Regulatory Commission Mail Stop T-6D-69 Washington, D.C.
20555-0001 Gentlemen:
INDUSTRY COMMENT ON PROPOSED NRC GENERIC LETTER (GL) 97-XX,
" LOSS OF REACTOR COOLANT INVENTORY AND ASSOCIATED POTENTIAL FOR LOSS OF EMERGENCY MITIGATION FUNCTIONS WHILE IN A SHUTDOWN CONDITION" TVA offers the following comments relative to Federal Reaister Notice (62 FRN7075, February 14, 1997) which solicited public comments on a proposed NRC GL requesting licensees to assess the susceptibility of their emergency core cooling systems (ECCSs) to common cause failure as a result of a reactor coolant system drain-down while in a shutdown condition.
The proposed GL requests that licensees determine whether their ECCSs are susceptible to common-cause failure as a result of events similar to the Wolf Creek reactor coolant system (RCS) drain-down event of September 17, 1994.
If ECCSs are found to be susceptible to such common-cause failure, addressees are expected to take corrective action as appropriate in accordance with the requirements stated in Section XVI of Appendix B to 10 CFR Part 50, to ensure compliance with the regulatory guidance provided in general design criteria (GDC) 34 and 35.
9 Comment:
This action request represents a major burden on licensees that is neither practical nor necessary.
Categorization and description of the permutations of valve lineups and potential misoperations that could contribute to RCS drain-down events would entail an exhaustive effort with little practical significance.
It is certainly important that each outage operation involving these valves be 9703190226 970314 PDR ADOCK 05000482 1
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Chief, Rules Review and Directives Branch
-Page'2 March 14, 1997 carefully reviewed with regard to drain-down potential at the time that the outage work is planned.
However, to attempt to accomplish this in advance for all possible combinations is simply not practical.
The number of combinations is so large that it would be difficult to guarantee an inclusive effort.
It is fundamentally more prudent to review these valve lineups and outage operations on a case-by-case basis, where the scope can be constrained to practical dimensions, and greater assurance'provided of an intensive review.
In addition, suitable consideration of redundancy, single failures, and power supplies ensures reliable operation of the ECCSs and residual heat removal system, and Technical Specifications preclude automatic ECCSs actuation during cold shutdown conditions.
Administrative and work controls must be relied upon for evolutions described by this event.
TVA utilizes a " protected train concept" as discussed in NUMARC 91-06, in conjunction with controls over emergent work activities.
The outage plan is configured and controlled to ensure the performance of key safety functions.
We. recognize the safety significance of the Wolf Creek event, but question the need for a GL as a means to further emphasize the importance of rigorous administrative controls to preclude creation of potential RCS drain-down paths due to simultaneous valve manipulations during outage conditions.
We believe that this has essentially been accomplished through implementation of NUMARC 91-06 and through industry reviews of the Information Notices resulting from the Wolf Creek event.
Further, we believe the actions requested by the proposed GL are unnecessary, given the work controls discussed above.
With regard to the backfit discussion of the proposed GL, we offer the following:
If the intent is to interpret 10 CFR 50.46 and the relevant GDCs to suggest that design features must be in place to preclude these types of events during shutdown operations, then we believe the proposed GL represents a significant backfit requiring a regulatory analysis.
Further, if the intent is for licensees to investigate and categorize all permutations of valve operations that could lead to this type of event, we believe this represents a significant revision to current practices i
for regulation relative to outage conditions and should be subject to regulatory analysis, i
e Chief, Rules Review and Directives Branch
~Page 3 March 14, 1997 TVA appreciates the opportunity to provide comments on this proposed GL.
If you have any questions regarding these comments, please contact E. W. Whitaker at (423) 751-6369.
Sin re.y,
/g$a
/Zyr Raul ron General Manager Nuclear Assurance and Licensing cc:
Mr. Ronald W. Hernan, Senior Project Manager U.S.
Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Rockville, Maryland 20852 Mr. Robert E. Martin, Senior Project Manager U.S.
Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Rockville, Maryland 20852 Mr. Luis Reyes, Regional Administrator U.S.
Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. M.
C.
Thadani, Project Manager U.S.
Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Rockville, Maryland 20852 Mr.
J.
F. Williams, Project Manager U.S.
Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Rockville, Maryland 20852 cc:
Continued on page 4
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Chief, Rules Review and Directives Branch "Pa'ge' 4 March 14, 1997
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cc:
NRC Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw Road Athens, Alabama 35611 NRC Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379 i
NRC Resident Inspector Watts Bar Nuclear Plant 1260 Nuclear Plant Road Spring City, Tennessee 37381 d
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