ML20082E424
| ML20082E424 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 07/29/1991 |
| From: | Vaughn G CAROLINA POWER & LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NLS-91-173, NUDOCS 9108010012 | |
| Download: ML20082E424 (5) | |
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Carolina Power & Light Company P O Box 1551 : Raleigh. N C 27602 JUL 291991 O f,$$,"
SERIAL:
NLS-91-173 y,
Nuclear Senaces Departrnent 10 CFR 50, Appendix J United States Nuclear Regulatory Commission ATTENTION: Document Control Desk Washington, DC 20555 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 50-324/ LICENSE NO. OPR-62 STATUS OF AND 10 CFR 50, APPENDIX J EXEMPTION FOR LLRT OF CONTAINMENT ISotATION VALVES IN THE REVERSE DIRECTION Gentlemen:
On January 28, 1991, the NRC issued a Safety Evaluation regarding the local leak rate testing (LLRT) of containment isolation valves in the reverse direction.
Reverse testing is applying the pressure differential across a component in the opposite direction than would be expected under loss-of-coolant accident (LOCA) conditions. In this evaluation, the staff concluded that the reverse testing of the containment isolation valves listed in Table 2 of the staff's safety evaluation, as currently performed at Brunswick, is non-conservative and requested CP&L to submit a proposed corrective action plan and schedule to test these valves in the accident direction. The staff identified acceptable methods for correcting this situation as revised test methods, plant modifications, or a request for exemption from 10 CFR 50, Appendix J requirements.
Carolina Power & Light Company is taking actions to enable future LLRTs for all but 2 of the valves for which non-LOCA direction testing was found to be non-conservative to be performed from the LOCA direction.
Modifications to install test connections which will allow LOCA direction testing of the remaining two valves (B32-V22, Recirculation Pump A Seal Injection Valve and B32-V30, Recirculation Pump B Seal Injection Valve) have been initiated.
However, due to the insufficient time available to perform the required engineering necessary to comp)<.te the installation of these modifications prior to the Unit 2, Reload 9 outage (currently scheduled to begin in September 1991), installation of these test connections will be completed during the Unit 2 Reload 10 outage, presently scheduled to begin in March 1993.
Therefore, CP&L hereby requests a one-time only exemption from the 10 CFR 50, Appendix J testing requirements for valves B32-V22 and B32-V30 for Unit 2 Reload 9, presently scheduled to begin in September 1991. Enclosure 1 contains the information necessary to support the Appendix J exemption request.
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In order to_ support outage planning and scheduling for the upcoming Unit 2, Reinad 9 outage CP&L requests approval of the proposed Appendix J exemption by September 11._1991 Please refer any questions regarding this submittal to Mr.
M. R. Oates at (919) 546-6063.
Yoursverytruly/,
swa/
s y-C. E. Vaughn GEV/ MAT
. Enclosure cc:
Mr. S. D. Ebneter
- Mr. N. B. Le Mr. R. L. Prevatte t
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c ENC? CSURE 1 BRUNSWICK STEAM ELECTRIC PLANT, UNIT 2 4
NRC DOCKET $0 324 i
OPERATING LICENSE DPR-62 APPENDIX J EXEMPTION REQUEST LIAT OF CONTAINMENT IS0laTION VALVES IN THE REVERSE DIRECTION Exemgtion Reauest' Appendix J,Section III.C.1 states, in part:
Type C tests shall be performed by local pressurization.
The pressure shall be applied in the same direction as that which the valve would be required to perform its safety function, unless it can be determined that the results from the tests for a pressure applied in a different direction will provide equivalent or more conservative results.
. On January 28, 1991, the NRC issued a safety evaluation regarding the local leak rate testing (LLRT) of containment isolation valves in the reverse direction. Reverse testing is applying the pressure differential across a component in the~ opposite direction than would be expected under loss-of-coolant accident (LOCA) conditions.
In this. evaluation, the staff concluded that-the reverse testing of the containment isolation valves listed in Table 2 of the staff's safety evaluation, as-currently performed at Brunswick, is. non conservative.
Carolina Power & Light Company is taking actions to enable future LLRTs for all but 2 of the valves;for which non-iDCA direction testing was found to be
.non-conservative to be performed from the LOCA direction. Modifications to install test connections which will allow LOCA direction testing of the remaining-two valves.(B32-V22, Recircule'. ion Pump A Seal Injection Valve and B32-V30, Recirculation Pump B Seal Injection Valve) have been initiated,
-However, due to the-insufficient time available to perform the required engineering necessary to complete the installetion of these modifications prior to the Unit 2, Reload 9 outage.(currently scheduled to begin in September 1991), installation of these test connections will be completed
'during the Unit 2 Reload 10 outage.
Therefore, in accordance with the
- provisions of 10 CFR 50.12, CP&L hereby requests a one-time only exemption from the 10 CFR 50, Appendix J testing requirements for valves B32-V22 and
- B3 2 -V30.-
11e requested exemption will allow one additional non-iDCA direction LLRT of these valves during Unit 2 Reload 9, presently scheduled to begin in September 1991.
Di.sussion Performing LLRTs in the non-LOCA direction for valves B32-V22 and B32-V30 provides either equivalent or more conservative results with regard to the seating surfaces. Valve B32-V22 is a gate valve which incorporates a wedge-shaped disk that seats on both seating surfaces simultaneously.
The valve actuator-exerts a closing thrust of approximately 1246 pounds, which is much greater than the containment test pressure of 49 psig.
Thus due to the El-1
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- Vedge design of the gate disk and the fact that the actuator exerts a force several times greater than that exerted on the disk by test pressure, two seating surfaces are maintained regardless of the direction in which the test pressure is applied.
Valve B32 V30 is a globe valve. Testing of globe valves from the non iDCA
- direction is more conservative because the test pressure attempts to lift the disc from its seat rather than com;^9ss it into the seat. Therefore, leakage measured during testing is likely to be of greater magnitude than that which would occur during a LOCA.
Per orm ng LLRTs in the non-LOCA direction for valves B32-V22 and B32-V30 does f
i not test the integrity of the packing. As stated above, valves B32-V22 and B32-V30 are recirculation pump seal injection valves.
They are located on 3/4-inch lines which connect to the reactor recirculation pump seals and are pressurized in excess of 1000 psig when the units are at power.
The stems of valves B32-V22 and B32-V30 measure 3/8-inches and 5/8 inches, respectively.
Thus, even a severe packing leak would create only a very small leakage path.
It has been demonstrated that a complete break of a 3/4-inch reactor vessel sampling and instrumentation line with 1/4-inch flow restrictor will not create environmental concerns in excess of other analyzed breaks.
A packing leak-through the stem area of either valve B32 V22 or valve B32-V30 would
- result in a leak which is no more severe than that resulting from a break in a sampling and instrumentation line. The valves are accessible from the 20 foot elevation, which is the entrance level to the reactor building.
As demonstrated above, (1) performing LLRTs of valves B32-V22 and B32-\\30 in the non-LOCA direction provides either equivalent or more conservative results with regard to the seating s2rfaces and (2), although packing integrity is not demonstrated, even a severe packing leak would create only a very small leakage path.
Therefore, granting the requested one-time only exemption from the 10 CFR 50, Appendix J testing requirements for valves B32-V22 and B32-V30 will not endanger life or property nor will granting the exemption have a significant impact on the environment.
10 CFR 50.12 Analysis Carolina Power & Light Company has reviewed this request and determined that the exemption may be granted pursuant to 10 CFR 50.12(a)(2)(iii) and (v), in that application of the regulation in this particular instance would result in an undue hardship and the exemption provides only tempbrary relief from the applicable Appendix J LLRT requirement, e
Modifications to install test connections which will allow LOCA direction testing of valves B32-V22 and B32-V30 have been initiated.
Installation of the test connections will be completed during the Unit 2 Reload 10 outage, presently scheduled to begin in March 1993. Performance of LOCA direction LLRTs on these valves during the upcoming Unit 2 Reload 9 outage would require disassembly of two check valves to remove their internals, thereby providing a path for LOCA direction pressurization of valves B32-V22 and B32-V30. The check valves are located in a high radiation area.
Based on an increase of measured Unit I dose rates and an assumed time for valve work, the Company has El-2
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.i estimated that the cumulative dose in disassembly and subsequently reassembly of the check valves would be in excess of 1.8 man-rem.
Actual doses could vary based on variance of the actual Unit 2 dose rates and job time.
Personnel concerns, associated with such a high dose job, outweigh the incremental benefit that would be derived from testing of valves B32-V22 and B32-V30 in the LOCA direction. As such, LOCA direction LLRTs of these valves would constitute an undue hardship.
Granting of this exemption will provide only temporary relief from the Appendix J LLRT requirement to test from the LOCA direction. This one-time exemption will allow non-LOCA testing of valves B32-V22 and B32-V30 during the upcoming Unit 2 Reload 9 outage. Modifications to install test connections which will allow LOCA direction testing of the valves have been initiated and will be completed during the Unit 2 Reload 10 outage.
j Summary Carolina Power & Light Company has made a good faith effort to comply with the requirements of 10 CFR 50 Appendix J requirements.
Subsequent to issuance of the NRC's January 28, 1991 safety evaluation, CP&L initiated actions to enable future LLRTs for all but 2 of the valves for which non-LOCA direction testing was found to be non conservative to be performed from the LOCA direction.
j Modifications to install test connections which will allow LOCA direction j
testing of the remaining two valves (B32-V22 and B32-V30) will be completed l
during the Unit 2 Reload 10 outage, presently scheduled to begin in March 1993.
In the interim, performing LLRTs of valves B32-V22 and B32-V30 in the non-LOCA direction provides either equivalent or more conservative results with regard to the seating surfaces and, although packing integrity is not demonstrated, even a severe packing leak would create only a very small leakage path.
Therefore, granting the requested one-time only exemption from the 10 CFR 50, Appendix J testing requirements for valves B32-V22 and B32-V30 will not endanger life or property nor will granting the exemption have t significant impact on the environment.
In addition, CP&L has reviewed this request and determined that performance of a LOCA direction LLRT during the upcoming Unit 2 Reload 9 outage would result in an undue hardship and the exemption provides only temporary relief from the applicable Appendix J LLRT requirement.
Therefore, the exemption may be granted pursuant to 10 CFR 50.12(a)(2)(iii) and (v).
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