ML18149A228
| ML18149A228 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 08/04/1986 |
| From: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Harold Denton, Rubenstein L Office of Nuclear Reactor Regulation |
| References | |
| 86-027A, 86-27A, TAC-60713, NUDOCS 8608080207 | |
| Download: ML18149A228 (8) | |
Text
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e VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 August 4, 1986 W. L. STEWART VICE PRESIDENT NUCLEAR OPERATIONS Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation Attn:
Mr. Lester S. Rubenstein, Director PWR Project Directorate No. 2 Division of PWR Licensing-A U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNIT NO. 2 ADDITIONAL INFORMATION FOR TYPE A TEST RELIEF Serial No.
86-027A NO/ETS/vlh Docket Nos.
50-281 License Nos. DPR-37 In a oletter dated February 7, 1986 (Serial No.86-027), we requested specific exemption for Unit 2 from 10CRF50, Appendix J Section III A.6(b),
which requires a Type A test every refueling shutdown, until, two consecutive Type A tests meet the acceptance criteria of Section III.D of 10CRF50, Appendix J.
In a March 21, 1986 telephone conversation with your staff, additional information was requested to support the Type A relief request.
The information requested is provided in a Discussion of Previous Unit 2, Type A Tests (Attachment 1).
In addition, a listing*
of the previous Type A tests and associated documentation is provided as Attachment II.
In reviewing Attachment.I, it can be seen that the key problems*
encountered with the Type A tests were:
- 1) programmatic in nature i.e.,
test boundary controls and test methodologies for Type A, Band C testing and 2) the result of a potential design problem with the containment sump trip valves.
As discussed in the February 7, 1986 letter, management attention has focused on the programmatic problems and corrective actions have resulted in significant improvements in the station's program* for Type A, B and C testing.
Attachment III lists seven major corrective actions which have been or are being implemented.
Items 1 through 6 are the programmatic improvements which have been made.
Item 7 covers the replacement of the containment sump trip valves which were identified as the contributor to the failure of the "as found" 1983 Type A test.
The*
corrective action plan for these valves provided for interim testing and maintenance at any cold shutdown until the valves could.be replaced with a ball valve design during the 1986 outages on both Surry units.
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e The corrective actions the Company has taken are consistent with IEIN 85-71 (SSINS NO: 6835).
IEIN 85-71 states that, if Type B and C leakage rates constitute an identified contributor to the failure of the "as found" condition for the Type A test, the general purpose of maintaining a high degree of containment integrity might be better served through an improved inaintainence and testing. program for containment penetration boundaries and isolation valves.
It further states that in such a situation the licensee may submit a corrective action plan with an alternative leakage test program proposal as an exemption request for NRC staff review in lieu of the required increase in Type A test frequency incurred after the failure of two successive Type A tests..
The dominant reason for unacceptable "as found" Type C test results was identified as the Containment Sump trip valves. The Company's corrective action program included increased testing and maintenance of these valves until replacement in 1986.
The Company has requested an exemption from a second Type A test on Unit 2 in an effort to minimize the number of times the containme~t structure is stressed to design basis accident conditions for test purposes.
Since the revised leak rate program and test methodology were implemented in early 1985, Surry has conducted two successful Type A tests, one on Unit 2 and one on Unit 1.
We believe that the corrective _actions outlined in this letter and its attachments are indicative of the conscientious testing program we now have in place to maintain containment integrity.
If you have additional questions or require further information, please contact us.
Very truly yours, W. L. Stewart Attachments
cc:
Dr. J. Nelson Grace Regional Administrator NRC Region II Mr. Albert F. Gibson, Acting Director Division of Reactor Projects NRC Region II Mr. W. E. Holland NRC Senior Resident Inspector Surry Power Station Mr. Chandu P. Patel NRC Surry Project Manager PWR Project Directorate No. 2 Division of PWR Licensing-A
I e
ATTACHMENT 1 Discussion of Previous Unit 2 Type A Tests A) March 1980 Test Two unsuccessful attempts were made at the 1980 Type A test. It was then discovered that eight holes had been drilled in the c~ntainment liner during the refueling outage for a modification to mount RTDs.
During the Type A test three of the eight holes were open.
The holes were plugged and a satisfactory Type A test was completed.
Since the holes were drilled during the outage, containment degradation during the previous plant operating cycle was not a concern.
Programmatic corrective actions were taken at that time to ensure that any future work that could affect the containment boundaries would be properly reviewed to ensure that proper leak rate testing is accomplished.
B) December 1981 Test Initial test results indicated a leakage of approximately 7.47 SCFM (1.5 La) and we found electrical penetration Al8 leaking significantly.
An attempt was made to quantify the leakage from penetration A18, but due to its location and size, the leakage could not be adequately measured.
A leakage of 3.75 SCFM was measured during the attempt.
The leakage was due to a loose collar bushing on B phase of the penetration.
The collar bushing was tightened eliminating the leakage through the penetration.
At that point, the integrated leak rate was approximately 2.0 SCFM and the test was restarted.
Comparing the final leakage results with the leakage results prior to repairing the penetration, it is estimated that the total leakage out of the penetration was approximately 5. 47 SCFM.
Because the electricians perform a weekly test (PT-34) of electrical penetrations during plant operations and leakage problems were not noted, the leak was not present during the previous operating cycle.
Prior to this Type A test, all Type B tests were performed at a pressure less than Pa (45 PSIG) and test results extrapolated to Pa.
This test method could have been the reason why leakage was not identified during Type B testing.
Since this test, Type B test procedures were revised to perform the tests at Pa to eliminate error associated with extrapolation to Pa.
C) September 1983 Test Prior to the 1983 Type A test, the steam generators were hydrostatically tested to 100 PSIG and the identified leakage was repaired. Initial test results were unsatisfactory due to leakage into the secondary system.
After discussion with, and concurrence from, the NRG inspector witnessing the test, the main steam valves were manipulated and the leakage fell to within acceptable limits giving us satisfactory test results at that time.
Following depressurization, the steam generators were hydrostatically tested again to identify the source of leakage, but no leakage was found.
After the satisfactory Type A test, the NRG inspector requested that we perform an "As-Found" analysis.
The required analysis was performed, but the exact leakage could not be quantified with existing equipment.
The "As-Found" test results for the penetration 38 (containment sump discharge) had the inside and outside trip valves with leakages of greater than 40 SCFH.
At that time, 40 SCFH was the largest rotameter in the station's Measuring and Test Equipment Program.
Since the exact leakage could not be quantified with the available rotameters, it had to be assumed that leakage exceeded the maximum allowable leakage limit of 300 SCFH.
Corrective actions which resulted from this test were that pressure tests of the steam generators would be performed with air rather than water prior to Type A tests.
This test method more accurately simulates the steam generator condition during the Type A tests.
Additionally larger rotameters were purchased so that Type B and C leakages could be quantified up to La.
An air test was performed on the steam generators prior to the successful completion of the June 1985 test, with a significant amount of leakage being identified and repaired.
The containment sump trip valves (penetration 38) were identified as being the dominant contributor to the Type C leakage.
As an interim measure pending valve replacement, more frequent testing of the valves has been performed.
Each time the unit goes to cold shutdown for a maintenance outage, the valves have been tested and repaired as necessary.
The long term resolution to the problem is replacement of the valves with valves more suitable for this application.
The Unit 1 valves were replaced with ball valves during the recent refueling outage.
We plan to replace these valves for Unit 2 during the next scheduled refueling (October 3 -
November 20, 1986).
D) June 1985 - Pretest Actions & Test Prior to the successful 1985 Type A test, further improvements were made in the Type A, B, and C testing programs.
These included utilizing the makeup method where practicable for Type C testing because more conservative testing results could be obtained. In addition to this, more stringent leakage criteria were developed for Type C valves.
The valve leakage was required to be within acceptable limits or the valves would be repaired or replaced.
This resulted in a greater number of valves
J" being repaired which had a signficant impact on the outcome of the 1985 test.
E) June 1986 -
(Unit 1)
The recent test on Unit 1 employing all of the programmatic improvements discussed in this attachment was successful.
J' TEST February 1980 March 1980 December 1981 September 1983 June 1985 ATTACHMENT 2 Surry Unit 2 Previous Type A Tests ASSOCIATED NRC INSPECTION 50-281/80-01 50-281/80-07 March 31, 1980 50-281/81-34 January 8, 1982 50-281/85-11 May 30, 1985 50-281/85-20 July 2, 1985
. i
- e ATTACHMENT 3 10CFR50, Appendix J - Containment Leakage Testing Corrective Action Plan Summary Surry Units 1 & 2
- 1)
Implemented strong programmatic controls for review of work affecting containment boundaries.
- 2)
Initiated performance of Type B tests at Type A pressure.
- 3)
Improved steam generator pressure testing methodology to be consistent with Type A conditions.
- 4)
Improved flow measurement instrumentation for quantifying Type Band Type C test leakage.
- 5)
Implemented makeup test methodology where practicable to obtain more conservative Type C test results.
- 6)
Established more stringent leakage criteria for Type C valve tests with limits for initiating valve repair or replacement.
- 7)
Replace the containment sump trip valves by the 1986 refuelings (Unit 1 complete) with an augmented interim surveillance and maintenance program.