ML20079N862
| ML20079N862 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 10/16/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20079N861 | List: |
| References | |
| NUDOCS 9111120052 | |
| Download: ML20079N862 (3) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO ONE-T1HE EXEMPTION FROM APPENDIX J TO ALLOW REVERSE-DIRECTION LOCAL LEAK RATE TESTING OF TWO CONTAINMENT ISOLATION VALVES CA_ROLINA POWER A LIGHT COMPANY BRUNSWICK STEAM ELECTRIC PLANT, UNIT 2 DOCKET NO. 50-324 1.0 lj{TR000CT10N By letter dated July 29, 1991, the licensee requested a one-time exemption from Appendix J to 10 CFR Part 50 to allow Type C (local leak rate) testing of two conteinment isolation valves in the reverse-direction for one-time only.
Section Ill.C.1 of Appendix J requires that for Type C testing the test pressure must generally be applied to the valve from the same side or same direction as would exist during an accident; i.e., usually test pressure is applied from the inside-containment side. However, the regulation allows an exception if it can be determined that testing with the pressure applied in the opposite or reverse direction provides equivalent or more conservative results. For Brunswick Steam Electric plant (BSEP), Unit 2, the staff found in a Safety Evaluation dated January 28,1991, that 16 of 51 containment isolation valves reviewed did not satisfy the equivalent-or-more-conservative requirement that allows reverse-direction testing. The licensee is taking steps to enable future Type C tests for 14 of these valves to be conducted by pressurization in the forward-direction as required by Appendix J.
The testing of the remaining two valves will also be corrected, but not until after the next required test for the valves. Therefore, the licensee has requested that these two valves be exempted from the forward testing requirement for their next Type C test (reload 9 outage, September through November 1991). The licensee will test them in the forward-direction for the following Type C test (reload 10 out n scheduled to begin March 1993).
2.0 EVALUATION The two subject valves are B32-V20, Recirculation P' imp A Seal injection Valve, and B32-V30, Recirculation Pump B Seal Injection Valve. The licensee has initiated modifications to install test connections which will allow forward-direction testing of these valves. However, due to insufficient time available to perform the engineering necessary to complete the installation of these modifications prio to the reload 9 outage (September through November 1991),
installation of these test connections will be completed during the reload 10 9111120052 911016 PDR ADOCK 05000324 p
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2-outage. Since Appendix J requires Type C testing at ever (although in no case at intervals greater than two years)y refueling outage the requested exemption will allow only one additional reverse-direction test of these valves, which will be during the upcoming reload 9 refueling outage.
Performing Type C tests in the reverse-direction for valves 832-V22 and 032-V30 provides either equivalent or more conservative results with regard to the seating surfaces.
Valve B32-V22 is a gate valve which has a wedge-shaped disk that seats on both seating surfaces simultaneously. The valve actuator exerts a closing thruct of approximately 1246 pounds, which is much greater than the containment test pressure of 49 psig. Due to this, the seating surfaces are not significantly affected by the direction in which the test pressure is applied.
Valve B32-V30 is a globe valve. Testing of this valve.in the reverse-direction-is more conservative because the test pressure tends to lift the disk from its seat rather than compress it into the seat. Therefore, leakage measured during reverse testing is likely to be of greater magnitude than that which would be measured in the forward-dii.ction.
Performing Type C tests in the reverse-direction for valves B32-V22 and B32-V30 does not test the leak integrity of the packing. As stated above, valves B32-V22 and B32-V30 arar recirculation pump seal injection valves. They are located on 3/4-inch lines which connect to the reactor recirculation pump seals ano are pressurized in excess of 100 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 small leakage path. The licensee states that 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 throtgh the stem aret of either valve B32-V22 or valve B32-V30 would result in a leak which is no larger than that resulting from a break in a sampling and-instrumentation line. The-staff finds that pctential packing leaks from these valves would not be likely to add significantly to the-consequences of a design-basis lo:s-of-coolant accident, nor to public risk during th3 interim until forward-direction testing will-begin.
As discussed above (1) nerforming Type C tests of valves B32-V22 and B32-V30 in the reverse-direction provides either equivalent'or more conservative results with regard to the seating surfaces, and (2) although packing integrity is not demonstrated, even a severe packing leak would create only a small leakage path.
Therefore, granting the requested one-time exemptioi from the Appendix J forward-direction testing requirertents for valves B32-V22 and B32-V30 is acceptable.
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3.0 CONCLUSION
Based on the above evaluation, the staff finds that the BSEP, Unit 2.
containment isolation valves B32-V22 and B32-V30 may be exempted from the forward-direction testing requirement of Appendix J for Type C tests and-W m..._
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d 3-instead will be reverse-direction tested until the reload 10 refueling outage at which time forward-direction testing will resume. The staff has determined that granting relief, pursuant to 10 CFR 50.55a(a)(3)(i) and 50.55a(g)(6)(i),
is authorized by law and will not endanger life or property, or the common defense and security and is otherwise in the public interest.
In making this determination the staff has considered the alternate testing being implemented, resulting hardships without a compensating increase in safety, or the impracticality of performing the required testing considering tne burden if the requirements were imposed.
Principal Contributor:
J. Pulsipher Date:
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DISTRIBUTION N1 Docket E11e; NRC PDR Local PDR T. Hurley/F. Miraglia 12-G-18 J. Partlow 12-G-18 C. Rossi 11-E-4 S. Varga 14-E-4 G. Lainas 14-H-3 E. Adensam 14-B-20 P. Anderson 14-B-20 N. Le 14-B-20 D.,'arrelli, Region 11 J. eulsipher OGC 15-B-18 GPA/PA 17-F-2 OC/LFMB AR-2015 E. Jordan MNCB-3302 J. Wechselberger Region 11 ACRS(10{4)
G. Hill P1-137 P-315 L. Reyes Rll PD21 Reading lile - Brunswick cc:
Plant Service List i
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