ML20236Q130

Ro:On 870812,reactor Tripped Following Safety Injection & Main Steam Line Isolation During Power Ascension.Caused by Fully Open Governor Valve.Necessary Equipment auto-started/ Actuated Per Design

ML20236Q130
Person / Time
Site:	Byron
Issue date:	10/19/1987
From:	Querio R COMMONWEALTH EDISON CO.
To:	Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
BYRON-87-1053, NUDOCS 8711190202
Download: ML20236Q130 (2)

Text

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LTR: BYRON 87-1053 i ij t FILE: 2.7.400 FILE,dA E Mr.: Ai Bert Davis

. Regional Administrator

Region 3 U.S. Nuclear Regulatory Commission

-799 Roosevelt Road'

'Glenn Ellyn, Illinois 60137

Dear Sir:

-This. report is'being submitted in accordance with Byron Station Unit 1 Operating license, NPF-37 Appendix A, Technical Specification 3.5.2 Action B.

This report addresses a Safety Injection' which occurred at Byron Station during a routine Unit 1 startup.

'On August 12, 1987, while returning to Power Operation, Unit 1 shift personnel were performing' Byron General Operating Procedure 1BGP 100-3 Power Ascension 5% to 100%. _Following a successful-turbine roll to 1800 RPM and Throttle

, Valve to Governor Valve. transfer, the turbine.was tripped per step 14 of 1 BGP 100-3. The trip resulted in all valves; TVs, GVs, Intercept Valves (IVs), and i Reheat'Stop Valves, going fully closed, and the turbine speed being reduced to 1 less than-1700 RPM.

With the activation of the Overspeed Protection Controller, the turbine speed l was lowered from 1850 RPM to approximately 1740 RPM and stabilized.. At this time the DEH controller was set to " OPERATOR AUTO" to maintain the selected j reference value of 1700 RPM. This action caused the GV.to go fully open.

With all GV fully open, main steamline pressure began to fall. When this pressure reached the 640 psig setpoint (this setpoint is rate sensitive. l

Actual pressure dropped from 1100 psig to 1040 psig), a Safety Injection and ]

Main Steamline Isolation were automatically initiated.

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l Bryon 87-1053 Page 2- 1 This Safety-Injection caused the reactor trip. The shift personnel entered {

Byron Emergency Procedure 1BEP 0, Reactor Trip or Safety. Injection Unit 1, and '

verified that the Reactor had tripped and the necessary equipment  ;

auto-started / actuated per design. 1 l

This is the eighth ' Safety Injection' that has occurred on Byron Unit 1.

i R. E. Querio Station' Manager l Byron Nuclear Power Station  ;

. REQ /JC/bf (0072z) cc: P. Brochman, NRC Senior Resident Inspector U.S. NRC Document Control Desk, Washington, D.C.

INPO Record Center CECO Distribution List R. Williams J. Cook i

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