ML20072S547
| ML20072S547 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/02/1994 |
| From: | Marsh W SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-89-10, NUDOCS 9409140123 | |
| Download: ML20072S547 (6) | |
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Southem Califomia Edison Company 23 PARKER STREET (RVINE, CAUFORNIA 92718 September 2, 1994 wAueR c. MARsR mE-MANAGER OF NUCLEAR REOULATORY AFFAIRS (714)4544403 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C.
20555 Gentlemen:
Subject:
Docket Nos. 50-361 and 50-362 Generic Letter 89-10, Motor Operated Valves San Onofre Nuclear Generating Station Units 2 and 3
References:
1.
August 29, 1990 F. R. Nandy (Edison) letter to the NRC (Document Control Desk),
Subject:
Implementation Programs for Generic Letter 89-10: Motor Operated Valves... San Onofre Nuclear Generating Station, Units 2 and 3 2.
August 28, 1992 Walter C. Marsh (Edison) letter to the NRC (Document Control Desk),
Subject:
Schedule for Generic Letter 89-10 " Motor Operated Valve Testing and Surveillance" 3.
October 29, 1992 NRC letter to Harold B. Ray (Edison),
Subject:
Extension of' Schedule for Completion of Testing Program in Response to Generic Letter 89-10 at San Onofre Units 2 and 3 In response to Generic Letter (GL) 89-10, by Reference 1 Southern California Edison (Edison) committed to perform in situ, design basis testing on all safety related Motor Operated Valves (MOVs) which are practical to test, except-for non-position changeable safety related MOVs. We have proceeded on this basis to date. However, based on our current level of experience and on the NRC guidance provided in Supplements 1 and 6 of GL 89-10, this letter is to inform the NRC that 18 of the total 178 MOVs in the GL 89-10 program in both San Onofre Units 2 and 3 will no longer be in situ, design basis tested, as had previously been planned. When needed, credit is taken fur grouping, which includes performing design basis testing on identical MOVs in the group, as part of the justification for not performing in situ, design basis testing.
Summarized below are the justifications for relaxing the commitment for in situ design basis testing of 18 MOVs which have been placed in 4 similarity groups. Even though the commitment for design basis testing is being relaxed, each M0V will be tested under static conditions.
In addition, with the
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. Document Control Desk exception of group 2 below, an identical MOV has been tested at maximum practical differential pressure (DP) and flow conditions in the other unit.
When grouping is used as a basis for eliminating dynamic design basis testing, the 7 grouping considerations of GL 89-10, Supplement 6 have been met.
The specific MOVs which will no longer be in situ, design basis tested and the bases for this reduction in testing scope are as follows:
1.
2HV6211, 2HV6216, 2HV6223, 2HV6236 These Unit 2 MOVs are Component Cooling Water Non-Critical Loop containment isolation valves. They are all Fisher Model 9220, 10" butterfly MOVs in a pumped, fluid flow application.
Results from design basis testing in Unit 3 indicate that valve shaft load requirements are well within design assumptions.
Acceptance of operability will be based on M0V design and application considerations and static testing of these MOVs.
In addition, final acceptance of these MOVs will include consideration of MOV capability based on EPRI Performance Prediction Program modeling.
2.
2HV9949, 2HV9950, 3HV9949, 3HV9950 These Unit 2 and 3 MOVs provide isolation for the Containment Purge system and are required to close on a Containment Purge Isolation Signal (CPIS) in Mode 6.
All of these MOVs are 42" Fisher Model 9220 butterfly valves. The design basis conditions for these MOVs are less than 1 psi at a flow of 38,000 cfm of air. These design basis conditions are considered essentially equivalent to static test conditions because of the very low DP and the fluid medium being air.
Tne design basis conditions are considered to be essentially equivalent to static test conditions because the affects of dynamic fluid flow i
forces on the valve during closure are very small due to the low air mass flow rate.
In addition, the effect of design basis differential pressure on operation of the purge valves is small because at the point of maximum throttling torque, during a closing dynamic stroke, torque due to differential pressure accounts for only 15% of the total required calculated dynamic torque. The majority of the total dynamic torque would be comprised of packing torque, gear box inefficiencies, and other l
losses.
l In addition, the minimum seating torque exceeds the maximum total dynamic torque in the closing direction by over 400%.
Therefore, effects due to only differential pressure are not only a very small portion of the dynamic torque, but are less than 3% of the minimum seating torque, i
l Grouping as allowed by GL 89-10, Supplement 6 is not the basis for relaxing the requirement for design basis testing of these valves.
l*
. Document Control Desk i Design basis testing is not considered useful because the effects of-design basis differential pressure and flow are insignificant with respect to non differential pressure related valve requirements such as packing torque or seating requirements.
l Acceptance of operability will be based on MOV design and application l
considerations and static testing of these MOVs.
In addition, final acceptance of these MOVs will include consideration of M0V capability based on EPRI Performance Prediction Program modeling.
3.
2HV9367, 2HV9368, 3HV9235, 3HV9240, 3LV02278, 3LV0227C These M0Vs are all Target Rock, parallel-disc gate valves in a pumped, fluid flow application. MOVs 2HV9367/8 are the Containment Spray Header containment isolation valves, 3HV9235/40 are the Boric Acid Makeup.
valves, and 3LV0227B/C are the Charging System suction valves.
l Design basis testing of 8 of the 14 MOVs in this group indicates that a valve factor of 0.45 will bound all test experience for this group.
Each.of these MOVs is controlled by limit switches in both the open and closed directions. Because these MOVs open and close on limit, operating margin is based on a calculation of minimum actuator capability.
An assessment of all MOVs in the group indicates that the Containment i
Spray valves have at least 40% margin. The Boric Acid makeup valves and the Charging System Suction valves have at least 150% margin.
Based on the successful design basis test ex)erience in this group and i
verification of significant design margin, t1ere is no benefit to be i
expected from design basis testing these remaining 6 MOVs.
Acceptance of operability will be based on MOV design and application considerations, satisfactory design basis test results for identical valves in the other unit, margins, and static test results for these MOVs.
4.
3HV9337, 3HV9339, 3HV9377, 3HV9378 These Unit 3 MOVs are normally-closed, WKM, split-disc gate valves.
They separate the reactor coolant system from the suction of the Shutdown Cooling system pumps.
Either the first two or the last two in this group must be opened to initiate shutdown cooling. They do not open against flow, and the only DP requirement is in the opening direction on initial cracking open of the valve disc. Because the open torque switch is fully bypassed, full actuator capability is available to overcome DP.
Open stroke testing of the identical valve with the same ap)1ication in Unit 2 indicates there is at least 75% margin to overcome t1e necessary valve disc pullout force.
Furthermore, the valves are stroked open near
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. Docu[nent Control Desk to design conditions every time they are opened to establish plant cold shutdown.
Acceptance of operability will be based on MOV design and application considerations, satisfactory design basis test results for identical valves in the other unit, margins, and static test results for these MOVs.
A listing of these 18 MOVs including similarity information is provided in.
With the 8 Unit 2 MOVs and the 10 Unit 3 MOVs no longer being design basis tested, as discussed above, Edison will still be design basis testing 77 MOVs at Unit 2 and 75 MOVs at Unit 3, which is 87% and 84% of the total GL 89-10 MOV population at Units 2 and 3, respectively. A summary of the number of MOVs being design basis tested is provided in Enclosure 2.
With the exception of the reduced number of MOVs to be design basis tested in the Cycle 8 refueling outages, all the commitments made in the August 28, 1992 Edison letter to the NRC (Reference 2), in which a schedule extension was requested for the San Onofre Units 2 and 3 GL 89-10 program, and the NRC requirements in the October 29, 1992 NRCletter(Reference 3),whichgranted the schedule extension, have been or will be met.
The direct costs associated with in-situ design basis testing have been conservatively estimated to be approximately $15,000 for each MOV.
Therefore, reducing the design basis testing scope by 18 MOVs will save approximately
$270,000 in direct costs.
If you have any questions or would like additional information, please let me know.
Sincerely,
$$$/
Enclosures cc:
L. J. Callan, Regional Administrator, NRC Region IV A. B. Beach, Director, Division of. Reactor Projects, Region IV K. E. Perkins, Jr., Director, Walnut Creek Field Office, NRC Region IV J. A. Sloan, NRC Senior Resident Inspector, San Onofre Units 2 & 3 M. B. Fields, NRC Project Manager, San Onofre Units 2 and 3
ENCLOSURE 1 SIMILARITY CHARACTERISTICS FOR 18 MOVs TO NO LONGER BE DESIGN BASIS TESTED i
SAN ON0FRE UNITS 2 AND 3 M0V No.
Mfg.
Type Size l
2HV6211 Fisher butterfly 10" l
2HV6216 Fisher butterfly 10" i
2HV6223 Fisher butterfly 10" 2HV6236 Fisher butterfly 10" 2HV9949 Fisher butterfly 42" 2HV9950' Fisher butterfly 42" 3HV9949 Fisher butterfly 42" l
3HV9950 Fisher butterfly 42" l
2HV9367 Target Rock parallel disc gate 8"
2HV9368 Target Rock parallel disc gate 8"
3HV9235 Target Rock parallel disc gate 3"
3HV9240 Target Rock parallel disc gate 3"
3LV0227B Target Rock parallel disc gate 3"
3LV0227C Target Rock parallel disc gate 3"
3HV9337 WKM split-disc gate 16" 3HV9339 WKM split-disc gate 16" 3HV9377 WKM split-disc gate 8"
3HV9378 WKM split-disc gate 8"
l
ENCLOSURE 2 GENERIC LETTER 89-10 MOVs DESIGN BASIS TESTING
SUMMARY
SAN ON0FRE UNITS 2 AND 3 UNIT 2 UNIT 3 89 89 TOTAL-GL 89-10 MOV POPULATION 4
4 DESIGN BASIS TESTS NOT PRACTICAL 8
10 DESIGN BASIS TESTS WILL NOT BE PERFORMED t
{
77 75 DESIGN BASIS TESTS-91%
88%
DESIGN BASIS. TESTING OF GL 89-10 MOVs I
WHICH ARE PRACTICAL TO TEST i
87%
84%
DESIGN BASIS TESTING OF GL 89-10 MOVs BASED ON TOTAL GL 89-10 POPULATION i
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