ML20057C954
| ML20057C954 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/29/1993 |
| From: | Marsh W SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9309300175 | |
| Download: ML20057C954 (4) | |
Text
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Southem Califomia Edison Company 23 PAJ4KEH STRf1T 5
IRVINE. CALWORNIA 92718 September 29, 1993 WAG ER C. MRSH MAa4A(mi R OF NtKM J_AH Fat OtJLATOHV AF F AlHS (714)464 4403 U. S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D.C.
20555 Gentlemen:
i
Subject:
Docket No. 50-362 Inservice Testing Program i
San Onofre Nuclear Generating Station Unit 3
Reference:
Letter from W. C. Marsh (SCE) to the Document Control Desk (NRC) dated August 16, 1993;
Subject:
Docket Nos. 50-361 and 50-362 l
Inservice Inspection Program (10 CFR 50.55a(g)) Schedule for the Second Ten-Year Interval, San Onofre Nuclear Generating Station, Units 2 and 3 The purpose of this letter is to submit Valve Relief Request (VRR) 27. The purpose of VRR 27 is to allow the use of portions of the 1989 ASME Code to determine valve leakage using pressure decay method techniques for the Unit 3 Reactor Coolant System (RCS) Pressure Isolation Valves (PIVs).
Testing of the Unit 2 counterpart valves during the recent refueling used the provision of the 1977, Summer 1979 addenda of the ASME Code and did not employ pressure
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decay methods. Approval of VRR 27 is requested by December 1,1993.
The first ten year interval for the Inservice Testing (IST) program, which was originally scheduled to end August 17, 1993, is governed by the 1977, Summer i
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 the referenced letter.
If the first ten year interval were 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.
-l Use of provisions in later editions of the ASME Code is consistent with ASME Section XI and allowed by 10 CFR 50.55a(f)(4)(iv), which states:
" Inservice tests of pumps and valves may meet the requirements set forth in subsequent editions and addenda that are incorporated by reference in paragraph (b) of this section, subject to the limitations and modification listed in paragraph (b) of this section, and subject to Commission approval. Portions of editions or addenda may be used j
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provided that all related requirements of the respective edition or addenda are met."
The Attachment to VRR 27 lists RCS-PIVs that already exist -in the IST program, but were previously tested by measuring leakage through tell-tale drains.
These valves have leakage 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 High Pressure Safety Injection (HPSI) f header check valves, Low Pressure Safety Injection (LPSI) header check valves, Hot Leg Injection line check valves, and Safety Injection Tank (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.
j 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.
Please let me know if you have any questions.
Very truly yours, Oh Enclosure cc: B. H. Faulkenberry, Regional Administrator, NRC Region V NRC Senior Resident Inspector's Office, San Onofre Units 1, 2 & 3 1
H. B. Fields, NRC Project Manager, San Onofre Units 2 and 3
Enclosure Page 1 of 2 l
VALVE RELIEF REQUEST No. 27 System:
Safety Injection Components:
Various (Refer to Table)
Cateoorv:
AC Class:
1 Function:
Seat leakage limits apply to each valve or group of valves Test Reauirement:
Article IWV-3424 of the 1977 Edition of the ASME Code states:
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" Valve seat leakage may be determined by one of the following:
"(a) draining the line, closing the valve, bringing one side to test pressure, and measuring leakage through a downstream telltale connection, or
"(b) by measuring the feed rate required to maintain pnMure between two valves or between two seats of a gate valve, provided the total apparent leak rate is charged to the valve or gate valve seat being tested, and thac the conditions required by Section XI, Article IWV-3423 are satisfied."
Basis for Relief:
ASME/ ANSI OM-1987, OMa-1988 Addenda, Operation and for Maintenance of Nuclear Power Plants will become the governing
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code for the second ten-year ISI interval, which will begin on April 1,1994.
The new code allows pressure decay for single valves as well as valve combinations (integrated leak rate 4
tests). Since the NRC approved the 1989 new code requirements, the test methods are an acceptable alternative to the testing methods of IWV-3424.
Alternate Testino:
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 shall be determined by one of the following:
-1 Enclosure 1
Page 2 of 2 i
"(1) measuring leakage through a downstream telltale connection while maintaining test pressure on one side of the i
valve; or
"(2) measuring the feed rate required to maintain test i
pressure in the test volume or between two seats of a gate valve, provided the total apparent leakage rate is charged to.
l the valve or valve combination or gate valve seat being tested, and that the conditions required by (b) above are j
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 i
being tested, and that the conditions required by (b) above i
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 in the attachment.
VRR 27 Table RCS PIVs Component Description S31204MU018 Check Valve HPSI Combined Header To RC Loop 1A S31204MUO19 Check Valve HPSI Combined Header To RC Loop 1B S31204MUO20 Check Valve HPSI Combined Header To RC Loop 2A i
S31204MUO21 Check Valve HPSI Combined Header To RC Loop 2B S31204MUO72 Check Valve LPSI/RC Loop 1A S31204MUO73 Check Valve LPSI/RC Loop IB S31204MUO74 Check Valve LPSI/RC Loop 2A S31204MUO75 Check Valve LPSI/RC Loop 28 S31204MU157 Check Valve HPSI Header to RC Loop 1 Hot Leg S31204MU158 Chack Valve HPSI Header to RC Loop 2 Hot Leg i
S31204MUO4C Check Valve, Safety Injection Tank T008 Outlet S31204MUO41 Check Valve, Safety Injection Tank T007 Outlet S31204MUO42 Check Valve, Safety injection Tank T009 Outlet S31204MUO43 Check Valve, Safety Injection Tank T010 Outlet