ML20058B124
| ML20058B124 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 11/19/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20058B106 | List: |
| References | |
| NUDOCS 9312010410 | |
| Download: ML20058B124 (5) | |
Text
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NUCLEAR REGULATORY COMMISSION e
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WASHINGTON, D.C. 20555-0001 ENCLOSURE SAFETY EVALVATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THE INSERVICE TESTING PROGRAM RELIEF RE0 VEST VRR 27 SOUTHERN CALIFORNIA EDISON COMPANY SAN ONOFRE NUCLEAR GENERATING STATION. UNIT 3 DOCKET NUMBER 50-362 INTRODUCTION lhe Code of Federal Regulations,10 CFR 50.55a, requires that inservice testing (IST) of certain ASME Code Class 1, 2, and 3 pumps and valves be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel Code and applicable addenda, except where relief has been requested and granted or proposed alternatives have been authorized by the Commission pursuant to 10 CFR 60.55a (f)(6)(i), (a)(3)(1), or (a)(3)(ii).
In order to obtain authorization or relief, the licensee must demonstrate that:
(1) conformance is impractical for its facility; (2) the proposed alternative provides an acceptable level of quality and safety; or (3) compliance would result in a hardship or unusual difficulty without a compensating increase in the level of quality and safety. Section 50.55a (f)(4)(iv) provides that inservice tests of pumps and valves may meet the requirements set forth in subsequent editions and addenda that are incorporated by reference in 10 CFR 50.55a(b), subject to the limitations and modifications listed, and subject to Commission approval. NRC guidance contained in Generic Letter (GL) 89-04,
" Guidance on Developing Acceptable Inservice Testing Programs," provided alternatives to the Code requirements determined to be acceptable to the staff and authorized the use of the alternatives in Positions 1, 2, 6, 7, 9, and 10 provided the licensee follows the guidance delineated in the applicable position.
When an alternative is proposed which is in accordance with Generic Letter (GL) 89-04 guidance and is documented in the IST program, no further evaluation is required; however, implementation of the alternative is subject to NRC inspection.
Section 50.55a authorizes the Commission to grant relief from ASME Code requirements or to approve proposed alternatives upon making the necessary findings. The NRC staff's findings with respect to granting or not granting the relief requested or authorizing the proposed alternative as part of the licensee's IST program are contained in this Safety Evaluation (SE).
In rulemaking to 10 CFR 50.55a effective September 8,1992, (see 57 Federal Register 34666), the 1989 edition of ASME Section XI was incorporated in 9312010410 931119 ADOCK0500g2 DR
- 10 CFR 50.55a(b). The 1989 edition provides that the rules for IST of pumps and valves shall meet the requirements set forth in ASME Operations and Maintenance Standards Part 6 (OM-6), " Inservice Testing of Pumps in Light-Water Reactor Power Plants," and Part 10 (OM-10), " Inservice Testing of Valves in Light-Water Reactor Power Plants." Pursuant to (f)(4)(iv), portions of editions or addenda may be used provided that all related requirements of the respective editions or addenda are met, and subject to Commission approval.
Because the alternatives meet later editions of the Code, relief is not required for those inservice tests that are conducted in accordance with OM-6 and OH-10, or portions thereof, provided all related requirements are met.
Whether all related requirements are met is subject to NRC inspection.
The licensee submitted pump inservice testing Relief Request VRR 27 in a letter dated September 29, 1993, which required evaluation by the staff. An evaluation of Relief Request VRR 27 is included below.
RELIEF RE0 VEST VRR 27 The licensee has requested relief from the Code seat leakage test requirements of ASME Section XI, Paragraph IWV-3424, for the reactor coolant system pressure isolation valves (RCS PIVs) in the high pressure safety injection (HPCI) and the low pressure safety injection (LPSI) systems and the safety injection tank (SIT) outlet check valves. The licensee has proposed to leak rate test these check valves by using the leak test method described in OM-10, Paragraph 4.2.2.3(c).
CFeck Valve Function S31204MU018 HPSI combined header to Reactor Coolant (RC) Loop 1A 531204MU019 HPSI combined header to RC Loop 1B S31204MU020 HPSI combined header to RC Loop 2A S31204MU021 HPSI combined header to RC Loop 2B S31204MUO72 LPSI/RC Loop 1A S31204MUO73 LPSI/RC Loop IB S31204MUO74 LPSI/RC Loop 2A S31204MUO75 LPSI/RC Loop 2B S31204MU157 HPSI header to RC loop 1 hot leg S31204MU158 HPSI header to RC loop 2 hot leg S31204MUO40 SIT T008 outlet S31204MUO41 SIT T007 outlet i
S31204MUO42 SIT T009 outlet S31204MUO43 SIT T010 outlet LICENSEE'S BASIS FOR RE0 VESTING RELIEF The licensee states:
ASME/ ANSI OM-1987, OMa-1988 Addenda, Operation and Maintenance of Nuclear Power Plants will become the governing code for the second ten-year IST interval, which will begin on April 1, 1994. The new Code allows pressure decay for single valves as well as valve combinations i
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' (integrated leak rate tests). Since the NRC approved the 1989 new Code requirements, the test methods are an acceptable alternative to the testing methods of IWV-3424.
ADDITIONAL INFORMATION INCLUDED IN LICENSEE'S SEPTEMBER 29. 1993. SUBMITTAL The licensee states:
...The first ten-year interval for the IST program, which was originally scheduled to end August 17, 1993, is governed by the 1977, Summer 1979 Addenda, of the ASME Code. The second ten-year interval at San Onofre Units 2 and 3 will be governed by the 1989 Edition of the Code which allows testing using the pressure decay method.
Southern California Edison (SCE) is extending the first ten-year interval to March 31, 1994, as allowed by Article IWA-2400(c) of the 1977 Edition, Summer 1979 Addenda, [as discussed in a submittal from the licensee dated August 16,1993].
If the first ten-year interval werc not being extended, the testing described in this letter would be permitted by the 1989 Edition of the ASME Code, and NRC approval would not be required...
...VRR 27 lists RCS-PIVs that already exist in the IST program, but were previously tested by measuring leakage through telltale drains. These valves have letkage requirements imposed on them by the Technical Specifications. Measuring the leak rate of these valves in accordance with the pressure decay method will save about 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> of critical path time during the unit 3 Cycle 7 refueling outage. The method is similar to that used at other plants, and will be permitted in our second ten-year interval program.
SCE intends to employ the pressure decay method for units 2 and 3 in the second ten-year interval.
The PIVs addressed in VRR 27 include the HPSI and LPSI header check valves, the hot leg injection line check valves, and the SIT outlet check valves.
In each of the safety injection paths, these valves, in combination with the associated RCS check valve, form the boundary of a test volume. The subject valves will be tested by pressurizing the piping volume between the respective check valve (s) and the RCS check valve.
In the case of the HPSI, LPSI and hot leg valves an isolation valve upstream of the header check valve will be opened to vent the upstream side of the valves.
Pressure decay in the pressurized test volumes will be correlated to a leakage value, which will be conservatively assigned to each check valve being tested. The RCS check valve is closed against RCS pressure and is assumed not to leak. This assumption will be verified before beginning the test by observing that the pressure in the test volume does not increase prior to opening the upstream isolation valve.
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ALTERNATE TESTING The licensee proposes:
Article IWV-1100 of the 1989 Edition of the ASME Code states:
" Valve testing shall be performed in accordance with the requirements stated in ASME/ ANSI OM (Part 10)."
Part 10, Paragraph 4.2.2.3(c) states:
" Seat Leakage Measurement.
Valve seat leakage measurement shall be determined by one of the following (methods]:
"(1) measuring leakage through a downstream telltale connection while maintaining test pressure on one side of the valve; or
"(2) measuring the feed rate required to maintain test pressure in the test volume or between two seats of a gate valve, provided the total apparent leakage rate is charged to the valve or valve combination or gate valve seat being tested, and that the conditions required by [the valve differential test pressure requirements discussed in 4.2.2.3(c)]...are satisfied; or
"(3) determining leakage by measuring pressure decay in the test volume, provided the total apparent leakage rate is charged to the valve or valve combination or gate valve seat being tested, and that the conditions required by [the valve differential test pressure requirements discussed in 4.2.2.3(c)]...are satisfied."
The purpose of this VRR is to allow use of the pressure decay method (Part 10, Paragraph 4.2.2.3(c)(3)) to test the PIV's listed [above].
EVALUATION P!Vs are defined as two normally closed valves in series that isolate the RCS from an attached low pressure system and are located at all RCS and low pressure system interfaces. These valves are categorized as Category A valves in the IST program. The Code requires that these valves be leak tested by measuring the valve leakage through a downstream telltale connection or measuring the feed rate to maintain a specific pressure. The licensee has proposed to use the leakage testing requirements of OH-10, Section 4.2.2.3(c)(3), which allow the valve leakage rate of Category A valves ta be determined by using a pressure decay test.
This test has been found to be an adequate method of measuring leakage.
The licensee stated that the valves will be tested by pressurizing the piping volume between the RCS check valve and the tested check valve.
Pressure decay in the test volume will be correlated to a valve leakage rate for each tested
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l PIV. A conservative correlation factor will be determined by the licensee for each individual pressure decay test. The test method described by the licensee meets the requirements of OM-10.
In rulemaking to 10 CFR 50.55a effective September 8, 1992, (See 57 Federal Reaister 34666), the 1989 Edition of ASME Section XI was incorporated in paragraph (b) of 10 CFR 50.55a. The 1989 Edition provides that the rules for IST of valves shall meet the requirements set forth in OM-10.
Pursuant to i
(f)(4)(iv), portions of editions or addenda may be used provided that all related requirements of the respective editions or addenda are met, and subject to Commission approval. The related requirements are found in i
Faragraph 4.2.2.3 of OM-10. Whether all related requirements are met is subject to NRC inspection.
CONCLUSION The staff finds the licensee's proposal acceptable and approves the use of OM-10, Paragraph 4.2.2.3, for valve leakage rate measurement pursuant to 10 CFR 50.55a(f)(4)(iv) provided the licensee meets the related requirements of OM-10.
The implementation of these requirements is subject to NRC inspection.
The staff has determined that approving the alternative pursuant to 10 CFR 50.55a(f)(4)(iv) is authorized by law and will not endanger life or property, i
or the common defense and security and is otherwise in the public interest.
Principal Contributor: Joseph Colaccino