ML20244A957
| ML20244A957 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 04/04/1989 |
| From: | Fox C TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 8904180290 | |
| Download: ML20244A957 (4) | |
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TENNESSEE VALLEY AUTHORITY 6N'38A Lookout Place l
APR 041989
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n U.S. Nuclear Regulatory Commission
, ATTN: Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of-
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Docket Nos. 50-327 Tennessee Valley Authority
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50-328-o SEQUOYAH NUCLEAR PLANT (SQN).- REQUEST FOR DISCRETIONARY ENFORCEMENT FOR
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UNIT 1 LIMITING CONDITION FOR OPERATION (LCO) 3.8.2.1 This letter serves to document TVA's request for discretionary enforcement for unit 1 LCO 3.8.2.1 because of the inoperability,of the 120-volt, alternating-current' vital inverter 2-IV.-
Discretionary enforcement to action statement b of LCO 3.8.2.1 for a period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> was determined to have no impact on unit 1 or common equipment affecting the safe operation of unit.1 and, therefore, should not force a shutdown of unit 1.
The-detailed justification for the discretionary enforcement is provided as an enclosure.
NRC' approval of the 24-hour discretionary enforcement for I.00 3.8.2.1 by D.-M. Crutchfield was provided to TVA by K. M. Jenison.
j If you have any questions concerning this issue, please call R. R. Thompson at (615) 843-7470.
Very truly yours, TENNESSEE VALLEY AUTHORITY
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C. H.
o, Jr.,
ce Presi nt and 1
Nuci Technical Direct r Enclosure cc: See page'2 g41802903904o4
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G ADOCM 05000327 '
PNU
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' An Equal Opportimity Employer
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. 4 U.S.' Nuclear Regulatory Commission
, APR 041989
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cci(Enclosure):-
Ms. S. C. Black, Assistant Director for Projects-TVA' Projects Division U.S. Nuclear-Regulatory Commission
'One White Flint,- North 11555 Rockville Pike-i Rockville, Maryland 20852 I
Ms. L. J. Watson, Acting Assistant Director ~
for. Inspection Programs TVA Projects Division U.S. Nuclear Regulatory Commission
' Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Sequoyah Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road
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Soddy Daisy, Tennessee 37379 1
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'e ENCLOSURE 1
c JUSTIFICATION FOR DISCRETIONARY ENFORCEMENT FOR UNIT 1 LIMITING CONDITION FOR OPERATION (LCO) 3.8.2.1 1
-At 0243 on' April 1, 1989, an unforeseen and apparent random failure of i
capacitors in vital = inverter 2-IV occurred.
The inverter serves.120-volt J(V),
R alternating-current (ac) vital instcument power board 2-IV (see Final Safety Analysis Report (FSAR) figures 8.1.2-2 and 8.3.1-32).
Technical Specification (TS) 3.8.2.1, "Onsite Power Dist:ibution Systems A.C. Distribution -;
.0perating," requires-the 120-9, ac vital instrument power' board channel.2-IV to be operable and energized from inverter 2-IV connected to direct-current
-(de) channel IV with either unit in modes 1 through 4.
LCO 3.8.2.1 was i
entered at 0243'for unit 1, which was operating in mode 1.
In accordance with the action of.3.8.2.1.b, the 2-IV board was energized to the alternate feed at 0256, and action was initiated to restore the inoperable inverter to operable status within 24' hours of the LCO entry.
While efforts continued to restore the inverter to operable status within the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, TVA determined that operating in excess of the LCO action statement i
would not place _the plant in.an unsafe condition and accordingly concluded a R
request for NRC discretionary enforcement was warranted. The event leading to this situation was an unforeseen component failure; continued unit 1 operation would not present a safety reduction, and timeliness of such NRC action was necessary to prevent the imposition of an unnecessary plant shutdown transient.
The situation was temporary and nonrecurring; therefore, a
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permanent. license amendment was not needed. The basis for.the determination-that operating in excess of the LC0 action statement would not place the plant in an unsafe condition is provided as follows.
The~ bases for LC0 3.8.2.1 state that operability of the ac power sources and associated distribution systems during operation ensures that sufficient power will be available to supply the safety-related equipment required for-safe-shutdown'and accident control and mitigation.
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- TVA has reviewed the loads served by 120-V, ac vital instrument power board 2-IV.
.This review was performed to determine the unit 1 and common loads connected to board 2-IV as shown in 45N706-4 (FSAR figure 8.3.1-32) and referenced drawings. This review was performed by SQN's Electrical Engineering Branch, Site Licensing, and Operations.
The following unit I and common equipment was found to receive power from board 2-IV:
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125-V de vital battery board IV - instrumentation
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Emergency gas treatment system room cooler A-A - FS-30-200 i
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Boric acid tank A heater B-B - control power i
- The affected instrumentation is the ammeter relay, the ground indicator relay, the ground indicator button, and the timing relay.
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'.o All other loads are unit 2 equipment that does not affect unit 1 operation.
The potential loss.of the three unit 1 and common loads above does not impact the operability of unit 1 TS equipment.
The loss of the 125-V, de vital battery board IV instrumentation would not impact operability of the battery board. All affected instrumentation is in the annunciation section of the board.
The loss of FS-30-200 disables the " auto" start of cooler B-B on low flow in cooler A-A, provided B-B is in " standby." However, normal alignment is to have the handswitches of both coolers in automatic so that both coolers start and operate under accident conditions.
Boric acid tank A heater B-B has a redundant heater A-A that is available and operating. Additionally, the boric acid tank is not currently being relied upon for compliance with TSs 3.1.2.2 and 3.1.2.6 (i.e., the refueling water storage tank is providing the borated water source requirement).
Because the unit 1 and common equipment powered from 120-V, ac vital instrument power board 2-IV will not impact the safe operation of unit 1, the continued operation of unit 1 beyond the 24-hour action statement allowable time is considered acceptable pending NRC approval.
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