ML20044A210
| ML20044A210 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 06/22/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20044A208 | List: |
| References | |
| NUDOCS 9006280211 | |
| Download: ML20044A210 (4) | |
Text
h, i
.. (g tto jo, UNITED STATES s
j',
I NUCLEAR REGULATORY COMMISSION
~
W ASHINGTON, D, C. 206b6
- g, SAFETY EVALVATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.142 TO FACILITY OPERATING LICENSE N0. DPR-32 VIRGINIA ELECTRIC AND POWER COMPANY l
SURRY POWER STATION, UNIT N0. 1 DOCKET NO. 50-280 I
1.0 INTRODUCTION
By letter dated January 8,1990, as clarified March 20 and April 20,1990, Virginia Electric and Power Company (the licensee) requested a one-time exemption for the Surry Power Station, Unit No.1 (Surry 1) from the requirements of 10 CFR Part 50, Appendix J pertaining to Type C leak rate test interval.
Paragraph III.D.3 of Appendix J requires that a Type C test be performed during each reactor shutdown for refueling, but in no case at an interval greater than 2 years. The licensee requested to extend the 2-year Type C test interval up to 27 weeks for 70 containment isolation valves which cannot be tested during power operation. The licensee proposes to test these valves at the scheduled Cycle.10 refueling outage.
The licensee' performed Appendix J tests for Surry 1 during the last refueling outage from April to July 1988 and completed the tests on June 23, 1988. Because of a subsequent extended shutdown in September 1988 for maintenance and modifi-cations that lasted 299 days, the next refueling outage (Cycle 10) is currently scheduled to connence on October 19, 1990 for the. fourth quarter of 1990. Con-sequently, the interval between the refueling outages will exceed the 24-month Type C test interval required by Appendix J. In order to avoid a plant shutdown solely for performing Type C testing the licensee requested a temporary TechnicalSpecification(TS)changefortherequestedexemptionbyaddinga footnote to TS 4.4.B.2 and TS 4.4.0.
^
The March 20 and April 20, 1990 letters provided clarifying information with regard to the proposed exemption request. Therefore the additional informationdidnotaltertiestaff'sinitialdetermInationofnosignificant hazards consideration as published in the Federal Recister on February 21 1990(55FR6124).
2.0 EVALUATION kn its January 8 and March 20, 1990 submittals, the licensee indicated that the required 24-month Type C test interval for the 70 valves will expire on June 23, 1990 and requested an exemption until December 31, 1990 to complete the tests. To support the exemption from the requirements of Appendix J, the licensee provided the following rationale:
(1) The intent of Paragraph III.D.3 of Appendix J, as interpreted by the licensee, is that Type C testing be performed during reft.eling outages but not to exceed 2 years of power operation. The actual inservice period 9006280211 900622 h
PDR ADOCK 05000280 P
},.
4.
2 during power operation for the majority of the components is less than the allowable 2 years due to the extended maintenance outage. Since 2 years of power operation will not have occurred, extending the 2-year interval is consistent with this intent.
(2) Primag containment integrity and compliance with the allowable leakage limit are not required when the reactor is in cold shutdown. An exemption would not be necessary, as considered by the licensee, in the event that Type C tests are not performed in 2 years if the interval expires during cold shutdown and the tests are completed prior to restart.
(3) The local leak rate test (LLRT) program has undergone significant changes and improvements to minimize leakage. The latest Type B and C test results are well below 0.6La limit.
(4) Compliance with the regulation would result in undue hardship or other costs in the form of lost revenues due to plant shutdown for performing i
Type C testing.
(5) Extending the LLRTs would not affect the probbilit.v ef occurrence of accidents.
Increasing the LLRT interval would a ho eliminate one heatup and cooldown cycle and lower the probability of events which are possible during such plant evolutiens.
The staff has 'eviewed the Appendix J exemption request and the associated justification and believes that the technical rationale has merit. However, the licensee's-interpretation that only the period of power operation needs to be considered is not convincing. The staff agrees that during a shutdown period the environment seen by a containment barrier can generally be considered to be less severe than power operation conditions. However, the licensee's interpretation implies that no barrier degradation occurs during cold shutdown.
The staff's experience with TMI-1 Appendix J 1eak rate testing during its long-time shutdown found that valves did degrade even if they were not in service. TMI-1 containment isolation valves were Type C tested almost every year during the cooldown period and increased valve leakage was found during each test. Extending LLRTs will increase the probability of valve leakage especially when the valve is aged. As a result, the staff interprets the time referred to within Appendix J as ca.1endar time. The intent of Appendix J Type C testing is to test valve leakage in a 24-month interval regardless shether the valve is exposed to power operation or not. Therefore, the staff finds this justification unacceptable with respect to supporting the Appendix J exemption request.
In assessing the possible degradation of containment integrity resulting from the extended test period, the staff has reviewed previous LLRTs performed at Surry 1 in 1986 and 1988. The total "as-found" leakage for.the 70 valves tested in 1986 was 910.12 standard cubic feet per hour (SCFH), which was a failed LLRT. Corrective action for valve repair and replacement was taken to red 9ee valve leakage. Following these repairs, the final "as-lef t" leakages for the combined Type B and C tests were 78.44 SCFH, which was below the 0.6La value of 180 SCFH. The total "as-found" leakage for the 70 valves tested in 1988 was 253.33 SCFH. Following valve repairing and replacement, the final
r
. "as-lef t" combined Type B and C leakages were 39.39 SCFH.
Based on this orevious LLRT data, the staff could not find evidence to assure that these l
valves will not degrade significantly in the extended period.
To properly address the staff's above concern with the initial submittal, the licensee provided additional information, via e letter dated April 20, 1990, for the 1986 and 1988 Type C test data and identified the valvos that had poor leakage history. The licensee indicated that the major contributors to the 1986 Type C test failure were valves TV-DA-100A/B,1-RM-3,1-1A-939, TV-SS-102A and TV-SS-101A/B with 300 SCFH directly attributable to valve TV-DA-100A/B. The licensee stated that these valves were repaired and retested satisfactorily. The major contributors to the 1988 Type C test failure were valves 1-RM-3,14RC-160, FCV-1160,1-1A-446, TV-SS-102A/B and TV-CA-150A with 107.5 SCFH directly attributable to valve FCV-1160. The licensee stated that valve FCV-1160 is water filled and not considered a credible leakage path. The staff has reviewed the leakage data for valves included in the aveattien recuest and finds that 70% of the valves tested in the "as found" condition hac very low leakage except for the valves mentioned above.
t The licensee also estimated leakage rates for the 1990 extended Type C testing based on 1986 and 1988 test results. The licensee first celculated leakage trend per month for each valve ard then found the projected leakage increase
-for the valve as a sumation of the 1988 "as found" leakage and the 30-month leakage trend.
If a valve had a negative leakage trend, the most recent "as found" leakage value was used for calculating the trend value.
For valves that l
were overhauled or replaced, a leakage trend was not projected. The projected t
leakage for the 70 velves was calculated to be 59.87 SCFH. The licensee then estimated leakages for all valves and penetrations using the same method and found the total "as found" leakages for combined Type B and C testing to be 134.56 SCFH. The staff has reviewed the valve leakage projection and finds that the methodology for estimating the leakage for the extended period is acceptable.
Furthermore, the estimated leakage for the 70 valves provides reasonable margin relative to the allowable limit of 180 SCFH.
Since the licensee has provided additional evidence to justify that extending the test interval should not result in a situation wherein the measured leakage from these valves would cause the 0.6La limit to be exceeded, the staff concludes that the licensee's requested exemption from Appendix J.is.
acceptable.
In the event of an unplanned, extended outage prior to the Cycle 10 refueling outage, the staff will require testing these 70 valves, with the following priorities suggested:
(1) first test the valves with the highest leakage history, (2) then test all stop check valves, (3) and then larger sized valves,(4)andfinally,testthesmallersizedvalves.
3.0
SUMMARY
Based on the above, the staff has concluded that the licensee's proposed one-time exemption from 10 CFR Part 50, Appendix J, paragraph III.D 3 and the proposed changes to TS 4.4.B.2 and TS 4.4.0 are acceptable provided all other valves are tested in accordance with Appendix J.
In the event that the Cycle 10 refueling outage is delayed by more than 2 months beyond the current projection of October 1990, this approval for deferral would become invalid and p
+...
.,.,o the licensee would have to seek new approval. This provision has been discussed with and found acceptable by the licensee's staff and has been incorporated into the proposed amendment to the TS.
4.0 ENVIRONMENTAL CONSIDERATION
Pursuant to 10 CFR 51.32 and 51.35, the staff has determined that the granting of the exemption and related amendment will not have a significant effect on-the quality of the human environment (55 FR 25754, June 22,1990).
5.0. CONCLUSION Wehaveconcluded,casedontheconsiderationsdiscussedabove,that(1)there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Dated: June 22, 1990 principal Contribut,or:
J. S. Guo u
t f
?
_