ML20004F962

Informs That Supply & Exhaust Dampers for Safeguards Bldg Engineered Safety Features Filter Train Are Seismic Category I.Damper Is Accessible for Manual Operation If Exhaust Damper Fails to Automatically Operate

ML20004F962
Person / Time
Site:	Comanche Peak
Issue date:	06/19/1981
From:	Schmidt H TEXAS UTILITIES SERVICES, INC.
To:	Burwell S Office of Nuclear Reactor Regulation
References
TXX-3315, NUDOCS 8106260348
Download: ML20004F962 (1)

Text

. ..

• • Duxz Powra COMPANY USNRC pgg..

• Powsm Butt.ptwo J TJ 3 N I.t' at ,/ ll 422 Socra Caumen Sruzzr, CnAmtorra N. C. asa4a " 91.".

'O !)A Y 4 ,a a

-, w a,. a .~ . . a ..

WCE P.tSIOgast

~: 0g Tgggresong; Aaga 704 ses ...oo cwo. April 28, 1981 373..o.2 Mr. Jaans P. O'Reilly, Director U.S. Nuclear Regulatory Commission Region II 101 Marietts Street, Suite 3100 Atlanta, Georgia 30303 Re: McGuire Nuclear Station Unit 1 Docket No. 50-369

Dear Mr. O'Reilly:

Please find attached Reportable Occurrence Report R0-369/81-37. This report

. concerns an inadvertent safety injection initiation. This incident was con-sidered to be of no significance with respect to the health and safety of the public.

V truly yours L ..- (4, -

William O. Parker, Jr.

RWO:pw Attachment ec: Director Mr. Bill Lavallee Office of Manage. ment & Program Analysis Nuclear Safety Analysis Center U.S. Nuclear Regulatory Co1mnission Post Office Box 10412 Washington, D.C. 20555 Palo Alto, California 94303 O.

• • g LU -

l T. v,s, n. , Ol k .i-e '

k.

" ascogD V' s -

slocco %% 6 #M '

f McGUIRE NUCLEAR STATION INCIDENT REPORT

. Report Number: 81-37 Report Date: April 16, 1981 Occurrence Date: March 30, 1981 Facility: McGuire Unit 1, Cornelius, N.C.

Identification of Occurrence: An inadvertent safety injection.was actuated on train A. ,

Conditions Prior to Occurrence: Initial fuel loading, Mode 5 Description of Occurrence: On March 30, 1981 during maintenance work on the Solid State Protection System (SSPS) cabinets, an inadvertent safety injection was initiated.

i Analysis of Occurrence: At approximately 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br />, technicians were trying to clear a feedwater isolation signal that was preventing the operators from opening the feedwater isolation valves. To work inside the logic section of the cabinet without disturbing the plant, the technicians placed the " Input Error Inhibit" switch in the " Inhibit" position and the " Mode Selector" switch in the " Test" position. The " Input Error Inhibit" switch inhibits the field. inputs to the cabinet and the " Mode Selector" switch isolates the output of the cabinet. After working in the cabinet but before completing the jch, the two technicians left the area. The switches were left in the aforementioned positions. During the cabinet work one or more of the permis-sive blocks, which prevent inappropriate Engineered Safety Feature (ESP) actuations, had been cleared from the logic memory. While the technicians were gone, their supervisor walked by the cabinets. Seeing all the alarms ,

cleared, he assumed that the job was finished and the technicians had for-gotten to return the test switches to their normal positions. He then  !

turnci the " Mode Selector" switch to " Operate" and the " Input Error Inhibit" {

switch to " Normal". A now unblocked ESF signal immediately initiated safety l injection on train LA. i After the reset timers timed out, the operators reset train 1A safety in-jection, phase A isolation and diesel generator load sequencer. The operators then proceeded to recover the plant by realigning systems and shutting down unneeded equipment that had started.

A technician was called to help get the feedwater isolation valves open.

The feedwater isolation valves are interlocked with the reactor trip breakers so that the breakers must be reset, or simulated reset, to open j the valves. The technician attempted to simulate the reset of the reactor l

1 trip breakers by lif ting and reconnecting a lead in the SSPS logic cabinet.

The operators had not reinserted the permissive blocks in the SSPS logic during the recovery process and the simulation of the closed reactor trip-breakers cleared the resets on train 1A safe.ty injection, phase "A" iso-lation and diesel generator load sequencer. Since the ESF signal was still

, . i present, unblocked, and the systems not reset, another safety injection was initiated. The operators again reset train lA safety injection, phase "A" isolation, and diesel generecor load sequencer. This time the permissive blocks were inserted by the operators using the switches on,the control board. 1 A procedure was not in use by the supervisor when the first safety injection was initiated nor by the technician when the second safety injection was initiated. A SSPS maintenance procedure (Procedure for Troubleshooting Solid State Protection Systemt (SSPS) During Critical Operation) was avail-able for use but did ac:: clearly describe the steps necessary *to return 'a train of the SSPS to normal operation. Operators were using a different procedure (ECCS Actuation During Plant Shutdown) to recover the plant after rue first safety injection, but.it did not mention inserting the permissive blocks after resetting the systems.

Safety Analysis: The safety injection had little effect on the plant be-cause the safety injection pump and centrifugal charging pump breakers were disconnected and the Residual Heat Removal System was aligned in the normal  !

shutdown cooling mode. No significant volume of water wcs added to the  !

Reactor Coolant System. The health and safety of the public were not af- .

facted. Similar incidents under other plant conditions could involve initiating whatever actions apply to the blocked ESP signals at those con-ditions.

Corrective Action: The inmediate corrective action was to recover the plant and insert the appropriate permissive blocks. Station management met with maintenance management and all I&E personnel involved in or responsible for the incident. The personnel were counseled about the severity of the incident and the necessity of preventing a reoccurrence.- The Procsdure for Troubleshooting Solid State Protection System (SSPS) During Critical Operation was rewritten to more clearly defit.a the steps necessary to re-turn the SSPS cabinets to operation after testing or maintenance. The

, Operations procedure ECCS Actuation During Plant Shutdown was modified to in-clude inserting the permissive blocks as part of the recovery process.

1 I

1 1 _ __ _. . .- - - - - - - _ - - ---- -.- - - . . - - - -