ML20210U827
| ML20210U827 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 03/06/1986 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML20210U520 | List:
|
| References | |
| FOIA-86-197 NUDOCS 8610100213 | |
| Download: ML20210U827 (5) | |
Text
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1 ENCLOSURE SAFETY EVALUATION DIABLO CANYON UNITS 1 AND 2 BATTERY TECHNICAL SPECIFICATION CHANGES By letter dated August 27, 1985, the Pacific Gas and Electric Company (PG&E) submitted License Amendment Request (LAR) 85-07. This request sought changes to the Diablo Canyon Units No. I and 2 combined Technical Specifications (TS) 3.8.2.1 and 3.8.2.2, Electric Power System battery sets and chargers. The change to TS 3.8.2.1 eliminates the possibility of indefinite cross-alignment of battery sets and chargers by adding an action statement to indicate that, with more than one full-capacity charger simultaneously receiving power from a single 480 volt vital bus, or any d.c. bus not receiving power from its associ-ated a.c. division, the system would be restored to a configuration where each charger is powered from its associated 480 volt vital bus within M days or be in at least hot standby within six (6) hours and in cold shutdown within the next 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
The wording of Section 3.8.2.2, item e, was proposed to be revised to clearly indicate that a 125 volt d.c. bus be energized from its associated battery bank, and a full-capacity charger be supplied from its associated operable a.c. Vital bus.
BACKGROUND By letter dated April 23, 1985, the staff provided to PG&E the final draft of the TS for Diablo Canyon Unit No. 2 for review and certification.
In that letter, the, staff stated that the procedures for combining the previously approved Unit No. 1 TS with those of Unit No. 2, as proposed by PG&E, would be addressed in a separate letter, fM Ol g 3 860930 HOLMFS86-197 PDR
. The staff presented to PG8E a letter dated May 15, 1985 which outlined a pro-cedure by which TS for units 1 and 2 could be combined. The letter identified areas which required specific attention to ensure consistency and to enhance the clarity of the combined TS. The letter further stated staff's intent to issue the combined TS when a full power license is approved for Unit No. 2.
Among the areas to which the staff directed specific attention was the Unit No. I technical specification related to battery sets and chargers. The staff suggested that "... the combined TS... clearly identify the charger / battery com-bination which will compromise the redundancy of the d.c. system in the event of a single failure." Given the alignment flexibility designed into the electric system, the staff's concern centered around the possibility of in-definite cross alignment of charger / battery combinations and the concurrent possibility of a single, vital a.c. bus indefinitely serving two battery /
charger / bus trains.
By letter dated May 21, 1985, PG&E responded to staff's suggestions, indica-ting reluctance to modify the combined TS to acconmodate staff's concern.
PG&E cited certain design features which would allow the battery / charger system to meet all applicable general design criteria, indefinitely, even if the system were to operate in a configuration that differs from its normal alignment.
Sub-sequent discussion between the NRC staff and PG&E resulted in the May 31, 1985 submission of LAR 85-07.
1 P
- Having reviewed LAR 85-07, the staff requisted additional information to support the selection of a 14 day cut-off period. The staff further requested information related to battery charger reliability and design analysis to support PG8E's position on the acceptability of operation in an alternate charger alignment. On June 14, 1985, PG&E supplemented its LAR-85-07 submission by providing the additional information requested by the staff.
Revision No. I to LAR 85-07 was submitted by PG8E by letter dated August 27, i
1985. This revision superceded the licensee's May 31, 1985 submission by requesting that LAR 85-07 be processed for the Units 1 and 2 combined TS, rather than for the Unit No. 1 TS alone.
SAFETY EVALUATION The staff finds the proposed changes to TS 3.8.2.1 and 3.8.2.2 to be accept-able. The changes grew out of discussions between staff and PG&E regarding combining the TS for Units No. I and 2 and are designed to place limiting con-ditions on operation of onsite electrical power systems which did not exist in the previously approved TS for the Diablo Canyon Unit No. 1.
The change proposed for TS 3.8.2.1 would limit to 14 days, the time the units could be operated in a cross-aligned configuration. This change ensures that the inde-pendence required by general design criterion no. 17 is not unduly compromised.
The change to TS 3.8.2.2 parallels the change to 3.8.2.1 by distinguishing i
.w-
. -4 specific chargers with specific battery sets. This change removes any potential ambiguity by establishing a baseline operating alignment for the on-site battery / charger system.
Because the above described changes constitute additional limitations which are not presently a part of the existing technical specifications, the pro-posed changes make the technical specifications far more restrictive and do not reduce the level of safety; therefore, the staff recommends their inclusion.
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ICSB SALP INPUT
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S BASIS
' PERFORf4ANCE EVALUATION CATEGORY CRITERIA 4
No basis for assessment.
Management N/A Involvement I
Understanding of issues generally apparent.
- j. Approad to
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2 i
Resslution of.
Technical Issues
.i
.' ['
Generally submitted timely responses.
2 ll. Responsiveness I
i
-l l'-
No basis for assessment.
N/A fI. Enforcement l
History
'j, 4
i N/A No basis for assessment.
! 5.
Reportable Events t
\\
T' No basis for assessment.
N/A
! 6.
Staffing
}
l I
- 7. Training N/A No basis for assessment.
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