05000275/LER-1985-001, :on 850102,while in Mode 1,low Flow in RCS Initiated Reactor Trip.Caused by Turbine Overspeed Protection Controller Sys Solenoid Valve Failure.Valve Replaced

:on 850102,while in Mode 1,low Flow in RCS Initiated Reactor Trip.Caused by Turbine Overspeed Protection Controller Sys Solenoid Valve Failure.Valve Replaced

ML20101U098
Person / Time
Site:	Diablo Canyon
Issue date:	02/01/1985
From:	Shiffer J, Sisk D PACIFIC GAS & ELECTRIC CO.
To:
References
CON-#185-467 DCL-85-044, DCL-85-44, LER-85-001, LER-85-1, OL, NUDOCS 8502060593
Download: ML20101U098 (3)

LER-1985-001, on 850102,while in Mode 1,low Flow in RCS Initiated Reactor Trip.Caused by Turbine Overspeed Protection Controller Sys Solenoid Valve Failure.Valve Replaced

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv), System Actuation
2751985001R00 - NRC Website

text

.

IBAC Paran NB U.S. IIUCLEAJ AGOULATORY 1

~~ -

M33 APPROVED Oess e.0 3150-4108 UCENSEE EVENT REPORT (LER) 8'""'8'**

PACILITY 8BAAAE (1)

OOCEETAIUEWOR831 FREE W DIABLO CANYON UNIT 1 o isioiolol2 7 5 i lopl 0l 2 i

TITLE del REACTOR C0OLANT SYSTEM LOOP LOW FLOW REACTOR TRIP SWWrf OATEISI LER seueWEn top mePOft? SATE (M OfteGR PACILitles IIgwoLvt0 m)

WONTM DAY YEAR YEAR MONTM DAY YEAR PACsLITT asassas DOCEEf feutAGGRtSt o15l0l0l0, i 1 0l1 0l2 85 8l5 0l 0l1 0l 0 0l2 0l1 8l 5 o isso io io, i i TMt6 ASPORT te gusaffTTED PURSUANT TO TME REOutettetsrTS Or te Cf R 9. (Chare e.e er.iere of one 4me.ouapf 411)

OPERAftase "I

I N 403th) 30.454e)

OB.78tmJOHivl 78.71 48 R

30eWteHING MJeteH1)

W.730sH3Hol TS.718el i 4,9 4.H, H.,

G,

. 736.H3H.

_OT. g g g n.,

R4WesH1HWI OS.730s)GHG W.736sH3HvalHA)

JESAJ 30.4004sH1Havl 90 730s}GHal 80.734mH3HveitHet 30 41steH1Het K794sH3HWI SO 73tetGHal LICEBISEE COAITACT FOR TMIS LER (131 NAME TELEPHONE NuneSER AREA CODE DAVID P. SISK, REGULATORY COMPLIANCE ENGINEER 8, 0,5 59,5,,7,3,5l i

i CORAPLETE 08st LI80E FOR EACH COngolsestT FAILUng OEEstiGED IN TMa8 REPO817 (13)

"'"yy"(^O k"$5'I "A

,"O "j,L' N

CAUSE

SYSTEM COMPONENT CAU$E sv8 TEM COh4PONENT e

n y

B TIG lFi SiV P070 N

i i

l i

I I I I I I l I

I l l I I I SUPPLitetNTAL REPORT EXPECTFJ 1141 MO, NTH DAV VEAR YES 499 pen, comense IJr9tCTED $Use,133,0N DATil NO l

l l

A=TxACT,-

,.oo

., e.

e-,, ~, e, n.,

b While in Mode 1 (Power Operation), the reactor tripped on reactor coolant system (RCS) low flow when a solenoid valve failure in the turbine overspeed protection controller (TOPC) system caused the turbine to slow with a corresponding drop in RCS flow. Diesel Generator 1-2 autostarted but did not load. While shifting to startup power, two of five containment fan cooler units, CFCU 1-1 and 1-4 tripped l

on thermal overload after autostarting on high speed.

The plant was stabilized in Mode 3 (hot standby) in accordance with procedures.

c All systems and equipment affected by this event were returned to normal operation. SV-41 was replaced with a spare and tested satisfactorily on January 4,1985, t

y t, 8502060593 850201 i

PDR ADOCK 05000275

}

S PDR UsI'""**

1

sostC F.ee MSA U $ NUCLEAR RESULATDAY COMMIS$304 UCENSEE EVENT REPORT (LER) TEXT CONTINUATION A,*aoveo ows No suo-om in,iais mi s FACsLITY esaast 118 DocEST Nualttm(29 v

L8m Nuest(R183 PAGE433 viaa "t'W

"'#3:

DIABLO CANYON UNIT 1 o 1510 lo lo l 21715 815 0l011 0l0 0l2 0F 0 12 runta -. %

M

anc,

,nm At 1945 PST, January 2,1985, with Unit 1 in Mode 1 (Power Operation), low flow in the Reactor Coolant System (AB) initiated a reactor trip during the performance of Start Up Procedure 43.7, " Net Load Trip From 50 Percent Power." A solenoid valve in the Turbine Overspeed Protection Controller (TOPC) System caused the turbine (TA) (TRB) to slow with a corresponding drop in RCS flow. All automatic equipment responded as designed. Diesel Generator 1-2 autostarted but did not load. When shifting to startup power, two of five Containment Fan Cooler Units (BK) (FCU),

CFCU 1-1 and 1-4 tripped on thermal overload after autostarting on high speed.

They were manually started in low speed. The high speed windings were reset and both CFCUs were successfully started on high speed. Operations personnel blocked the Low Pressure Safety Injection (LPSI) signal to prevent an unnecessary safety injection actuation from post trip conditions, i.e., steam demand from the Auxiliary Steam System and Main Turbine Pilot Trip Valve leakage. The LPSI setpoint was never reached and the block was reset when plant conditions were stabilized.

The trip was caused by a solenoid valve failure in the Turbine Overspeed Protection Controller (TOPC) System. This system causes the turbine governor (TA) (FCV) and intercept (TA) (ISV) valves to close for short periods to prevent turbine overspeed during transients. TOPC Solenoid Valve SV-41 stuck open during the load rejection transient. This prevented the governor (TA) (FCV) and intercept (TA) (ISV) valves from reopening, thus allowing the Turbine (TA) (TRB) to slow, and generator-frequency to approach 54 Hertz. The reactor coolant pump's speed dropped as frequency dropped. This lowered flow in the reactor coolant system causing an RCS loop low flow reactor trip.

The plant was stabilized in Mode 3 (Hot Standby) in accordance with procedures.

All systems and equipment affected by this event were returned to normal operation. SV-41 was replaced with a spare and tested satisfactorily on January 4,1985. Start Up Test 43.7 was completed satisfactorily on January 5,1985 This event was a previously analyzed Condition II event and had no effect on the health and safety of the public.

i f

1

.,c,..M -

l

si f

PACIFIC OAS AND E LE C T RIC C O M PANY bb'Mb l

77 BEALE STREET. SAN FRANCISCO, CALIFORNIA 94106. (415) 781-4211. TWX 910 372-6587 d*"*

February 1,1985 IsuCLEAR POWER GENERATION PGandE Letter No.: DCL-85-044 Document Control Desk U. S. Nuclear Regulatory Commission Washington, D.C.

20555 Re: Docket No. 50-275, OL-DPR-80 Diablo Canyon Unit 1 Licensee Event Report 85-001-00 ESF Actuation - Reactor Trip Gentlemen:

Pursuant to 10 CFR 50.73(a)(2)(iv), PGandE is submitting the enclosed Licensee Event Report concerning the inadvertent actuation of an engineered safety feature, reactor trip.

This event has in no way affected the public's health and safety.

Kindly acknowledge receipt of this material on the enclosed copy of this letter and return it in the enclosed addressed envelop.

Sincerely,

/

J.

hiffer Enclosure l

cc:

J. B. Martin l

Service List l

l Y h