ML20011D748
| ML20011D748 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 12/27/1989 |
| From: | Rosenblum R SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML19310C572 | List: |
| References | |
| REF-GTECI-023, REF-GTECI-NI, RTR-NUREG-CR-4821, RTR-NUREG-CR-4948 NUDOCS 8912280354 | |
| Download: ML20011D748 (5) | |
Text
__
i f0E
)
Southern California Edison Company 23 PARKER STREET IRVINE, CALIFORNIA 92710 R.u RosEwotuu December 27, 1989
,, j53,"j,
'5 04UCLE AM REGULATORY AFFAIRS U. S. Nuclear Regulatory Commission 1
Attention: Document Control Desk
)
Washington, D.C.
20555-Gentlemen:
Subject:
Docket Nos. 50-361 and 50-362 Reactor Coolant Pump Seals, Requested Information San Onofre Nuclear Generating Station Units 2 and 3 4
References:
1)
M. O. Medford (SCE) to Document Control Desk (NRC) letter dated December 1, 1988;
Subject:
Appendix R Audit Open Items 2)
M. O. Medford (SCE) to G. W. Knighton (NRC), letter dated March 4,
1986;
Subject:
Reactor Coolant Pump Seal Planned Modifications This letter provides addition el information regarding Reactor Coolant Pump (RCP) seal integrity which was requested by the NRC Staff during a' telephone conversation on August 15, 1989.
In Reference 1, Southern California Edison (SCE) stated that the RCP seals would maintain integrity for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> without j
seal cooling and the pumps not rotating.
In Reference 2, SCE stated that RCP seals would maintain integrity for 30 minutes without seal cooling and the RCPs j
rotating.
To understand the bases for the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and 30 minute RCP seal integrity periods, the NRC requested that SCE provide the following information:-
1)
How 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> seal integrity was verified; 2)
The basis for 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> seal integrity.
3)
Additional detail regarding SCE's test that verified RCP seal integrity for 30 minutes.
In response to item 1), the assumption that the RCP seals would retain their integrity for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> is based on-tests on Byron Jackson (BJ) RCP seals as-documented in NUREG/CR-3226, " Station Blackout Accident Analysis," dated May.
1983. This NUREG stated that, in te'sts performed on BJ RCP Seals without seal cooling and non-rotating RCPs, BJ seals exhibited no appreciable leakage (approximately I gpm) after 56 hours6.481481e-4 days <br />0.0156 hours <br />9.259259e-5 weeks <br />2.1308e-5 months <br />.- The original RCP seals at San Onofre 8912280354 891227 A
PDR ADOCK 05000361
'8 P
PDC t
t l
l-l 4
Document Control Desk December 27, 1989 Units 2 and 3 were BJ seals. As stated in SCE to NRC letters dated February 22, 1985 and March 4, 1986, these seals were replaced with Bingham Willamette Company (BWC) RCP seals during 1986-1987 for both units as part of an effort to extend RCP seal life.
The BWC seals were evaluated and tested by SCE and were found to be superior (improved elastomers, improved cooling, etc.) to the original BJ seals. As requested by the NRC staff, the 10 CFR 50.59 analysis by which the RCP seal replacement was made is provided as Enclosure I to this letter.
Because the NRC-indicated in NUREG/CR-3226 that the BJ seals would not leak for 56 hours6.481481e-4 days <br />0.0156 hours <br />9.259259e-5 weeks <br />2.1308e-5 months <br /> with non-rotating RCPs and without seal cooling, SCE concluded that the superior BWC seals would be acceptable for at least 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> under the same conditions.
j Additionally, SCE has reviewed the NRC's August 31, 1989 response to CE0G comments on Generic Issue 23, RCP Seal Leakage (Enclosure II) as it applies to l
RCP seal failures at CE0G plant s.
In this letter, the NRC states "there l
appears to be a disproportionately larae number of (RCP seal failure) events involving the types of RCP seals used et CE0G plants." The enclosure to this NRC letter lists recent industry RCP seal failure events and tabulates the failures by nuclear steam supply system (NSSS) vendor and seal vendor. Of the 16 RCP seal failures listed, only 1 failed seal is a Bingham Willamette seal (non-CEOG plant) and all of the CE NSSS RCP seal failures listed involved only Byron-Jackson seals. As stated above, SCE has replaced the original Byron Jackson RCP seals at San Onofre Units 2 and 3 with Bingham Willamette seals.
This seal replacement has resulted in a drastic reduction in the RCP seal failure rate.
(The mean time to failure for a BJ RCP seal at San Onofre i
Units 2 and 3 was90-120 days.
For the BWC RCP seals, the mean time to i
failure for one stage of the three stage design is greater than 3 years).
Therefore, the BWC RCP seal performance at San Onofre Units 2 and 3 demonstrates that the NRC's generalized statement regarding CE0G plant RCP I
seal performance is not applicable to our units.
In response to item 2), the SCE Appendix R Compliance Assessment Re) ort provided by SCE to NRC letter dated May 31, 1987, identified that tie Component Cooling Water (CCW) system is required to be in operation-to support charging pump operation within 60 minutes following a safe shutdown fire.
However, the Appendix R Analysis for San Onofre Units 2 and 3 conservatively assumed that CCW would not be able to provide cooling to the RCP seals for the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after a safe shutdown fire due to assumed fire related equipment inoperability. The following describes procedural actions necessary to mitigate the postulated fire related loss of component cooling event:
1.
Following verification of a safe shutdown fire, the plant operators are directed by the post-fire safe shutdown procedures to immediately trip the reactor and the RCP's.
(The RCP's would be tripped in less than 30 minutes.)
i
Document Control Desk _ December 27, 1989 2.
Plant operators would then direct manual actions to restart the CCW pumps and align CCW to support charging pump operation.
These manual actions would occur within-the first 60 minutes post-fire.
3.
After restoring systems necessary for safe shutdown und stabilizing plant conditions, plant operators would direct manual actions outside the control room to align CCW to the RCP seals.
The Appendix R Section III.G compliance evaluation credited local manual valve operation to restore CCW to the RCP seals between 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />
- and 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after a safe shutdown fire. This 16 hour1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> period was verified to be sufficient time for plant operators to manually align the required CCW valves to provide seal cooling to the RCPs.
In response to item 3), Enclosure III to this letter provides:
1)
Test Procedure 2PE-211-02, Rev. O, " Loss of Cooling Water to a Bingham Boiler Circulation Pump Mechanical Shaft Seal Demonstration Test at Alamitos Unit 3 - (Pump Operating)," dated November 1, 1985.
2)
Bingham Willamette Report 5023-9232-0, " Post Test Inspection for Loss of Cooling Test," performed on November 1, 1985.
We believe this letter completes the responses to all outstanding NRC RCP seal questions. However, if you have additional questions, please contact me.
/
Very truly yours, g
k lA )
J i
l Enclosures cc:
J. B. Martin, Regional Administrator, NRC Region V C. Caldwell, NRC Senior Resident Inspector, San Onofre Units 1, 2 and 3 i
- Consistent with Appendix R Section III.J 8-hour emergency lighting need not i
be provided for local manual operation of the required valves.
l
{
l L
l
5 4
1 I
e a
,1 1
'1 i
ENCLOSURE I l
l l
P i
i i
{
i i
e I
i.1 a-
'