ML16342D151
| ML16342D151 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 12/26/1995 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML16342D150 | List: |
| References | |
| NUDOCS 9512280291 | |
| Download: ML16342D151 (4) | |
Text
gp,R RE0y
~4
~o 0
C O
IIA e
++*++
UNITED STATES NUCLEAR REGULATORY COMMISSION VIASHlNGTON, D.C. 205554001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO MAIN STEAM SAFET VALVE AUGMENTED TESTING AND INSPECTION PROGRAM PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON NUCLEAR POWER PLANT UNITS 1
AND 2 DOCKET NOS.
50-275 AND 50-323
- 1. 0 INTRODUCTION On October 1,
1995, the NRC issued License Amendments 107 and 108 for Diablo Canyon Nuclear Power Plant, Units 1 and 2.
The amendment approved a main steam safety valve (MSSV) setpoint tolerance of 23% (+3/-2% for the lowest set MSSVs).
As a part of these license amendments, the NRC requested that, for at least one operating cycle, the licensee submit a plan for performing augmented inspection and testing of the valves on a more frequent basis than that required by the ASHE Code.
The NRC request was based on concerns regarding
'the variability and magnitude of HSSV setpoint tests performed during September 1995 on both Unit 1
and 2 HSSVs.
During this testing, the licensee observed that after a period of power operation, several initial lifts exceeded
+3% of the nominal setpoints, but that several of the second lifts were within +1% of the nominal setpoints..
By letter dated November 1,
- 1995, the licensee submitted its augmented MSSV testing and inspection program.
- 2. 0 EVALUATION The licensee's proposed program for augmented testing of the Unit 1
HSSVs would test the plant HSSVs at more frequent intervals than required by the ASME Code until the Unit 1 eighth refueling outage (1R8).
The MSSVs would be tested one steam header at a time on a staggered
- basis, with varying intervals
'between tests of valves on different headers.
The licensee stated that the augmented testing is intended to provide a set of on-line test data for each of the five valves on each of the four headers.
The licensee also stated that testing to meet the requirements of Technical Specification (T/S) 3.7. l. 1 and the ASME Code will be performed for all the Unit 1 HSSVs just before 1R8.
The licensee stated that for the augmented testing, if the HSSVs are not within
+1%, but are within the TS 23% tolerance
(+3/-2X <or the lowest set HSSVs),
the valves will be reset.
However, in an effort to preserve the time-related aspect of the test data, testing would not be immediately expanded beyond the five valves on the test header.
Should the testing be expanded, the licensee has agreed to discuss the scope of additional testing with the NRC staff.
The staff finds that the proposed Unit 1
MSSV augmented testing program is acceptable for addressing the staff's concern regarding the variability and magnitude of the observed MSSV setpoint tests.
95i228029i 95i220 PDR ADQCK 05000275 6
\\
For the Unit 2 HSSVs, the licensee proposes to perform the TS 3.7. 1. 1 and ASHE Code testing prior to the Unit 2 seventh refueling outage (2R7), scheduled to begin on Harch 16, 1996.
Additional testing of the Unit 2 HSSVs prior to 2R7 is,not planned because of the significant testing of the HSSVs performed during September 1995.
The staff finds this acceptable due to the relatively short operating period remaining until the beginning of 2R7 and the augmented testing to be performed for Unit 1 prior to 1R8 as discussed above.
The licensee is also performing additional laboratory testing and inspection to determine if seat-to-nozzle bonding due to galling or oxide bonding is
- present, and the licensee is verifying the adequacy of the current testing methodology (i.e., with AVK test equipment) using full-pressure steam testing.
This is also acceptable to the staff since these activities will further identify the nature of the plant HSSV setpoint phenomena and determine whether the current testing methods are valid.
3.0 CONCLUSION
The staff has reviewed the licensee's submittal dated November 1,
- 1995, and has determined that the augmented testing and inspection plan described therein is acceptable.
Principal Contributor:
G.
Hammer Date:
December 26, 1995
I4 0
~
'lu p)
I
- l'