ML20057C372
| ML20057C372 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/24/1993 |
| From: | Marsh W SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9309280280 | |
| Download: ML20057C372 (5) | |
Text
'
,y f f Southem Califomia Edison Company 23 PARKER STREET IRVINE, CALIFORNIA 92718 September 24, 1993 WAG ER C. MARSH MANAGER OF NUCLEAR REGULATORY AFFAIR 5 (714)464 4403 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Gentlemen:
Subject:
Docket Nos. 50-361 and 50-362 Additional Information for Amendment Applications 132 and 116 Transformer Replacement San Onofre Nuclear Generating Station Unit 3
References:
1)
April 13, 1993 letter from Harold B. Ray (SCE) to Document Control Desk (NRC),
Subject:
Docket Nos. 50-361 and 50-362, Amendment Application Nos. 132 and 116, Changes to Technical Specifications 3/4.8.1, "A. C. Sources," San Onofre Nuclear Generating Station, Units 2 and 3 l
2)
June 11, 1993 letter from W. C. Marsh (SCE) to Document Control Desk (NRC),
Subject:
Docket Nos. 50-361 and 50-362, i
Additional Information for Amendment Application Nos.132 and 116, Transformer Replacement, San Onofre Nuclear Generating Station, Units-2 and 3 3)
June 15, 1993 letter from Mel B. Fields (NRC) to Harold B.
Ray (SCE),
Subject:
Issuance of Amendment for San Onofre Nuclear Generating Station Unit No. 2 (TAC No. M86362) and Unit No. 3 (TAC No. M86363).
This letter is being sent to provide information regarding the replacement of 4kV/480V transformers at San Onofre Unit 3 and to request NRC approval for..a revision to the Safety Evaluation Report included in Reference 3.
Backaround By reference 1, Southern California Edison (SCE) requested a one-time exception to Technical Specification (TS) 4.8.1.1.1.a to allow the electrical cross-tie between Units 2 and 3 to remain OPERABLE for up to 120. hours while the transformers were being replaced.. In reference 2, SCE stated that, with one exception, the 125 VDC battery bank that is fed from the 4kV/480V transformers would remain OPERABLE throughout the transformer replacement A
b 9309280280 930924 PDR ADOCK-05000361 3
i 4
P PDR gQ 1
Document Control Desk ' work. The exception to this was when train B 4 kV bus 2A06 was out of service for maintenance, for a maximum of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />..The one-time exception was approved on June 15, 1993, as documented by reference 3.
t In order to minimize the overall out of service time of the Train A 1E electrical sources, SCE is requesting a revision to the plan for the transformer replacement at Unit 3 to allow for concurrent discharge testing of the 125 VDC battery bank on Train A.
Train A Transformer ReDlacement During the work to replace the train A 3B04X transformer, the 125 VDC battery bank 38007 will undergo. discharge testing. However, bus 3D1, which normally receives power from battery bank 38007, will be maintained OPERABLE through use of a hardwired connection between 125 VDC battery bank 3B009 and bus 3D1 (See Figure 1). This will maintain the unit cross-tie OPERABLE, except briefly during the connection of the battery-to-bus cross-tie.
The hardwired l
connection runs from 125 VDC bus 3D3, through breakers 3D306 and 3D106, to 125 l
VDC bus 3D1.
Battery charger 38003, which powers 125 VDC battery bank 3B009, normally receives power from the same 480 V bus 3B04 that will be INOPERABLE due to the transformer replacement. While battery bank 3B009 is relied upon to supply l
power to bus 3DI, battery charger 3B003 will be connected to an alternate power source. The alternate power alignment will come from the offsite l
transmission network through Unit auxiliary transformer 3XVI or Reserve i
auxiliary transformer 3XR1, through 4kV/480V transformer 3B16X, 480 V bus l
3B16, and 480 V MCC 3BX, to the battery charger 3B003. During this period, l
battery bank 3B009 will be maintained OPERABLE in accordance with TSs 4.8.2.1.a.1, 3.8.2.1.b, and 3.8.2.2.b.
This temporary alignment provides the same level of reliability as the temporary alignment approved by the NRC in Reference 3.
The new temporary alignment will be subject to the same Surveillance Requirements and administrative controls as those approved for the original temporary alignment in Reference 3.
Breakers 3D102 and 3D101 connect battery charger 3B001 and battery bank 38007 to bus 3D1. These breakers will be maintained open during discharge testing l
of battery bank 3B007 when the hardwire connection from bus 303 is being used.
l This is to prevent damage to the bus, battery charger, and battery bank.
Train B Transformer Replacement During the work to replace the train B 3B06X transformer, the OPERABILITY of the 125 VDC battery bank will be maintained in an identical manner to that used during the Unit 2 Cycle 7 refueling outage. Maintenance on the train B 4 kV bus 3A06 will require the cross-tie to be rendered INOPERABLE for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Discharge testing of the battery bank will start at the beginning i
l of the work window for the transformer replacement and the 4 kV bus 3A06 maintenance. Unit 2 will be in the TS 3.8.1.1 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> ACTION statement for both the 3A06 maintenance work and discharge testing simultaneously. Once the
i Document Control Desk
- 4 kV bus and the 125 VDC battery bank are returned to OPERABLE status, the 125 VDC battery bank will be maintained OPERABLE in accordance with TSs t
4.8.2.1.a.1, 3.8.2.1.b and 3.8.2.2.b.
During the Unit 2 Train B transformer replacement, temporary Non-1E power supplied from Unit 2 sources was provided to the battery charger for the Train B 125 VDC battery bank. During the Unit 3 Train B transformer replacement, temporary Non-1E power supplied from Unit 3 sources will be provided to the battery charger for the Train B 125 VDC battery bank (See Figure 2).
Summarv l
t
(
NRC approval of the alternate provisions for maintaining the unit cross-tie i
OPERABLE, as discussed above, is requested in support of the upccming Unit 3 l
i l
Cycle 7 refueling outage. The Train B transformer replacement is currently scheduled for approximately the second week of the outage.. The Train-A i
t transformer replacement is currently scheduled for approximately the sixth week of the outage. NRC approval is requested as soon as possible to facilitate the outage planning.
. I If you have any questions regarding this matter, please let me know.
l Sincerely, i
be cc:
B. H. Faulkenberry, Regional Administrator, NRC Region V NRC Senior Resident inspector's Office, San Onofre Units 1, 2, and 3 M. B. Fields, NRC Project Manager, San Onofre Units 2 and 3 i
9-c.
-w.. -.,
w, I