05000346/LER-1981-024-03, /03L-0:on 810418,bus J Was Rapidly Taken Out of Svc W/O Providing for Alternate Power Supply for Decay Heat Pump 1-1.Caused by Personnel Error.Procedure Modified & Operator Informed of Mods

/03L-0:on 810418,bus J Was Rapidly Taken Out of Svc W/O Providing for Alternate Power Supply for Decay Heat Pump 1-1.Caused by Personnel Error.Procedure Modified & Operator Informed of Mods

ML19345H583
Person / Time
Site:	Davis Besse
Issue date:	05/18/1981
From:	David Brown TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19345H582	List: 05000346/LER-1981-024, Forwards LER 81-024/03L-0 05000346/LER-1981-024-03, /03L-0:on 810418,bus J Was Rapidly Taken Out of Svc W/O Providing for Alternate Power Supply for Decay Heat Pump 1-1.Caused by Personnel Error.Procedure Modified & Operator Informed of Mods
References
LER-81-024-03L, LER-81-24-3L, NUDOCS 8105210303
Download: ML19345H583 (3)

LER-1981-024, /03L-0:on 810418,bus J Was Rapidly Taken Out of Svc W/O Providing for Alternate Power Supply for Decay Heat Pump 1-1.Caused by Personnel Error.Procedure Modified & Operator Informed of Mods

Event date:
Report date:
3461981024R03 - NRC Website

text

U.S. NUCLEAR REGULATORY COMMISSION NRC F,oRM 366,

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60 61 DOCKET NUV8ER 68 69 EVENT OATE 74 75 REPORT DATE 80 EVENT OESCRIPTION AND PROBABLE CONSEQUENCES h tol2l l (NP-33-81-26) On 4/18/81 at 0330 hours0.00382 days <br />0.0917 hours <br />5.456349e-4 weeks <br />1.25565e-4 months <br />, it was necessary to rapidly take 345 KV Bus I

It was isolated l g l "J" out of service due to two burning potential devices on that bus.

lo I4 l l per SP 1107.01.

However, the loads on the 13.8 KV Bus "A" power supply from J

l Startup Transformer "01" (which is fed by "J" bus) had' not been transferred to "02".

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o 5 [o Is 1 l The result was the loss of Decay Heat Pump 1-1 and entry into the action statement of l l 0 l 7 l l T.S. 3.4.1.

There was no danger to the health and safety of the public or station l

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43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS ltl0ll The cause was personnel and procedural error.

In an attempt to rapidly isolate the l bus, operators failed to provide an alternate-power supply for DH Pump 1-1 prior to i i

, 7 l isolating "J" bus. The procedure only provides a short note of warning. DH Pump 1-1l

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Memo 81-1013 was writtenj g l was restarted 1 minute and 28 seconds after it was stopped.

to inform the operators and modification M-4853 was written for procedure SP 1107.01.

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J TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-81-26 DATE OF EVENT: April 18, 1981 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Inadvertent Loss of Decay Heat Flow Conditions Prior to Occurrence: The unit was in Mcde 5 with Power (MWT) = 0 and Load (Gross MWE) = 0.

Description of Occurrence: At 0330 hours0.00382 days <br />0.0917 hours <br />5.456349e-4 weeks <br />1.25565e-4 months <br /> on April 18, 1981, Power Systems instructed Davis-Besse Operations to take 345 KV Bus "J" out of service as soon as possible due to the discovery of two burning potential devices on that bus. An equipment' operator was quickly dispatched to the switchyard to isolate "J" bus per SP 1107.01, "345 KV Switchyard, No.1 (Main) Transformer, No,11 (Auxiliary) Transformer and Startup Transformars (01 and 02)", Section 10.

A "no signoff" note in this procedure requires the Reactor Operators to transfer 13.8 KV bus "A" power supply from Startup Transfos r

T "01" (which is fed by "J" bus) to Startup Transformer "02" prior to isolating "J" bus.

The Reactor Operators failed to transfer the "A" bus power supply before "J" bus was isolated. As a result, essential 4160 volt bus Cl was de-energized via loss of power to "A" bus and non-essential 4160 volt bus "C2".

At the time, reactor coolant system decay heat cooling flow was being provided by Decay Heat Pump 1-1 (which is powerei by bus Cl) and, as a result of the loss of power to bus "Cl", Decay Heat Pump 1-1 was de-energized and decay heat flow was lost at 0351:36 on April 18, 1981. Loss of-bus "Cl" initiated an automatic start of Emergency Diesel Generator 1-1 and power was restored to bus "Cl" at 0351:42 on April 18, 1981. Decay heat flow was restored at 0353:04 on April 18, 1981.

Loss of Decay Heat Pump 1-1 placed the unit in. violation of the action statement of Technical Specification 3.4.1 which states that while in Fbdes 3, 4, or 5 and with no reactor coolant pumps running, operations may proceed provided at least one reactor Total time in coolant loop is in service with an associated decay heat removal pump.

j which the Reactor Coolant System was without decay heat flow was one minute, eight I

seconds, Designation of Apparent Cause of Occurrence:

This occurrence was caused by a combina-i tion of operator error and procedural inadequacy. The Reactor Operators,'in their attempt to isolate "J" bus as quickly as possible, failed to provide an alternate power supply for Decay Heat Pump 1-1 prior to having their equipment operator isolate "J" bus.

Procedurally, SP 1107.01, Section 10 does not provide adequate instructions to provide an alternate power supply for "A" bus. At present, it only provides a short note to ensure that air circuit breakers HX01A and HX01B, the breakers which connect "01" transformer to the 13.8 KV buses, are open prior to taking "J" bus out of service.

There is no signoff required for this note.

LER #81-024

I TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR PO'JER STATION UNIT ONE PAGE 2 SUPPLEMENTAL INFORMATION FOR LER NP-33-81-26 Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. Heatup of the reactor coolant system was minimal as decay heat flow was lost for a very short time (one minute, eight seconds) and the condi-tion of the reactor coolant systen (atmospheric pressure and approximately 1000F) was such that it could have accommodated a loss of decay heat removal for longer periods of time without causing damage to the reactor.

Corrective Action

Power was restored to essential 4160 volt bus "C1" by the auto-I matic start of Emergency Diesel Generator 1-1 at 0351:42 on April 18, 1981, and the operators restored decay heat flow by starting Decay Heat Pump 1-1 at 0353:04 on April 18, 1981.

A major modification, M-4853, has been written for SP 1107.01 to provide a separate signoff for shifting 13.8 KV bus power supplies prior to taking the 345 KV buses out of service. All operations personnel have been made aware of this occurrence through Intra-Company Memorandum #M81-1013.

Failure Data: Previous inadvertent loss of decay heat flow was reported in Licensee Event Reports NP-33-80-54 (80-054), NP-32-80-14 (80-060), and NP-32-80-12 (80-058) which includes three incidents.

LER #81-024 9

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