05000346/LER-1978-037-01, /01T-0:on 780430,plant Procedure Violated During Maint Shutdown.Caused by Personnel Error & Procedure Inadequacy.Plant Shutdown & Cooldown Procedure Mod Prepared to Keep RCS Above 280 F If Cooldown Line Isolated

/01T-0:on 780430,plant Procedure Violated During Maint Shutdown.Caused by Personnel Error & Procedure Inadequacy.Plant Shutdown & Cooldown Procedure Mod Prepared to Keep RCS Above 280 F If Cooldown Line Isolated

ML19326A438
Person / Time
Site:	Davis Besse
Issue date:	05/10/1978
From:	Batch S TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19326A437	List: 05000346/LER-1978-037, Forwards LER 78-037/01T-0 05000346/LER-1978-037-01, /01T-0:on 780430,plant Procedure Violated During Maint Shutdown.Caused by Personnel Error & Procedure Inadequacy.Plant Shutdown & Cooldown Procedure Mod Prepared to Keep RCS Above 280 F If Cooldown Line Isolated
References
LER-78-037-01T, NUDOCS 8002030266
Download: ML19326A438 (3)

LER-1978-037, /01T-0:on 780430,plant Procedure Violated During Maint Shutdown.Caused by Personnel Error & Procedure Inadequacy.Plant Shutdown & Cooldown Procedure Mod Prepared to Keep RCS Above 280 F If Cooldown Line Isolated

Event date:
Report date:
3461978037R01 - NRC Website

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8 60 El coc.N ET NUMB E R 68 69 EVENT oATg 74 75 REPoRToATE 80 EVENT DESCRIPTICN AND PROBABLE CONSEQUENCES h toinl l During the process of shutting down the unit for the maintenance outage Step 6.2.3 I

y ; of Plant Procedure FP 1102.10. " Plant Shutdown and Cooldown", was violated. Decay l

o,,il Heat Cooldown Isolation Valves DHil and DH12 were not opened prior to reducing Reactor l go,3, ; Coolant System (RCS) temperature below 2800F.

There was no danger to the health and l lo is l l safety of the public or unit personnel.

The unit was well within allovable pressure /l jo;7; l te=perature limitations for cooldown.

(NP-32-78-03)

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TOLEDO EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STAuCN SUPPLEMENTAL INFORMATION FOR LER h7-32-78-03 DATE OF EVENT: April 30, 1978 FACILIIT: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE:

Reactor Coolant System temperature below 280*F

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with the normal cooldown line isolated.

Conditions Prior to Occurrence: The unit was in Mode 4, with Fower (MRT) = 0, and Load (MWE) = 0.

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. Description of Occurrence: During the process of shutting down the unit for the maintenance outage, Step 6.2.3 of Plant Procedure ?? 1102.10, " Plant Shutdown and Cooldown", was violated.

Decay Heat Cooldown Isolation Valves DH11 and DH12 were not opened prior to reducing Reactor Coolant Systes (RCS) tc=perature below s

28007. These valves are required to be open to provide a flowpath to relief 3

valve DH4849 for overpressure protection of the RCS when below 2800F per 10CFR50 Appendix G.

RCS ' temperature decreased below 2800F at approxi=ately 1030 hours0.0119 days <br />0.286 hours <br />0.0017 weeks <br />3.91915e-4 months <br /> on April 30, 1978, and reached a low temperature of 2500F at approxi=ately 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br /> on April 30, 1978.

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This incident requires NRC verbal and written notification within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and a follow up report within 14 days per Technical Specification 6.9.1.8f.

Region III

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of the NRC was notified by both telephona and telecopy on May 1,1978.

jf Occurrence: The cause of this occurrence is Designation of Apparent Caus.

both personnel error and procedure inadequacy for the circu= stances of this At the time of this occurrence, relief valve DH4849 was removed for occurrence.

surveillance testing and to repair a slight leak.

This forced the RCS to re=ain at an intermediate temperature for an extended period of ti=e.

The " Plant Shut-down and Cooldown Procedure", PP 1102.10, was being followed up until the relief valve was removed. While holding up the unit shutdown for the relief valve testing, RCS temperature was allowed to decrease below 2800F.

Operations per-sonnel should not have allowed RCS temperature to decrease below 2800F, and the l

procedure should specifically address this com=itment.

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There was no danger to the health and safety of the public

'Analvsis of Occurrence:

or to unit personnel. The unit was well within allowable pressure /tenperature li=itations for cooldown.

I LER 478-037 l

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TOLEDO EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-32-78-03 PAGE 2

Corrective Action

Valves DH 11 and DH 12 opened at 0200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> on May 1, 1978.

A modification was prepared to the Plant Shutdown and Cooldown Procedure, PP 1102.10, to assure the requirement of keeping the RCS above 2800F if the cooldown line is isolated is understood.

Failure Data: This is not a repetitive occurrence.

LER #78-037 b

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