05000373/LER-1982-022, Forwards LER 82-022/03L-0.Detailed Event Analysis Encl

Forwards LER 82-022/03L-0.Detailed Event Analysis Encl

ML20054F713
Person / Time
Site:	LaSalle
Issue date:	06/10/1982
From:	Holyoak R COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20054F714	List: 05000373/LER-1982-022, Forwards LER 82-022/03L-0.Detailed Event Analysis Encl 05000373/LER-1982-022-03, /03L-0:on 820523,emergency Makeup Train Heater Temp Switch for Control Room HVAC Tripped.Caused by Inadvertent Closure of Tornado Damper Which Blocked All Suction to Train Thus Raising Temp & Tripping Switch
References
NUDOCS 8206170242
Download: ML20054F713 (2)

LER-1982-022, Forwards LER 82-022/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3731982022R00 - NRC Website

text

N commonwealth Edloon o

) LaSalle County Nuclear Station Rural Route #1, Box 220 L

Marseilles, Illinois 61341 Telephone 815/357-6761 June 10, 1982 James G. Keppler Regional Administrator Directorate of Regulatory Operations, Region lll U. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137

Dear Sir:

Reportable Occurrence Report #82-022/03L-0 Docket #050-373 is being submitted to your office in accordance with LaSalle County Nuclear Power Station Technical Specification 6.6.B.2. (b), conditions leading to operation in a degraded mode permitted by a limiting condition for operation or plant shutdown required by a limiting condition for operation.

kh. A b R. H. Holyoak Superintendent LaSalle County Station RHH/GW/djp Enclosure cc: Director of Inspection & Enforcement Di rector of Management Information & Program Control U. S. NRC Document Management Branch inpo-Records Center File /NRC 1519gg 8206170242 820610 PDR ADOCK 05000373 S

pyg 5 Eb.D

I.

LER NUMBER:

82-022/03L-0 11.

LASALLE COUNTY STATION:

Unit 1 Lil. DOCKET NUMBER:

050-373 IV.

EVENT DESCRIPTION

During the performance of LOS-VC-M1, operating surveillance to verify operability of the control room HVAC emergency make up train, on 5/22/82 atOr 2000 hrs. It was discovered that the heaters high temperature switch (manual reset) had tripped, de-energizing the trains' heater.

V.

PROBABLE CONSEQUENCES OF THE OCCURRENCE The primary function of the emergency make up train is to protect the control room environment in the event of a high energy gamma release from the plant stack and to remove smoke from the outside air in the event of a high lonization alarm.

There are no sources of gamma radiation at this point of plant operation.

in the event of an initiation of the emergency make up train on high ionization, the normal supply filter odor eater could also have been put in effect as a backup measure. Therefore, the health safety and capability of the control room operator was not jeopardized.

VI.

CAUSE

The heater of the emergency make up train energizes upon start of the emergency make up fan, and will trip upon hi temperature in the area of

~_

the heater; upon a no air flow condition; upon a fan stop.

The no air flow trip occurs only af ter an cs 30 second time delay.

Outside air radiation monitor 2D18-K751 A failed hi due to moisture in the detector (re: LER 82-021/03L-0) initiating the emergency make up train, at the same time the tornado damper OVC01YB had inadvertently closed due to mechanical problems.

When the train initiated on the false hi rad signal and ran with no suction source, the heater had no airflow to remove the heat generated, and remained energized for about 30 seconds.

During this time of no air flow the temperature became hi enough to trip the temperature swi te.h.

This incident occurred on 5/15/82 at Od 2150 hrs.

Re:

LER 82-021/03L-0.

Vll. CORRECTIVE ACTION The temperature switches associated with the heater were recalibrated on W.R. 15859 to insure they were not set at too low a value; this was accomplished by 1930 hrs on 5/25/82.

The "B" emergency make up train was declared operable on 5/27/82 at 0315 hrs.

Also, the temperature indicating loops for train inlet and outlet are being recalibrated on this same W.R.

to insure prcper control room indication.

The heater trip logic on no air flow will be revised with a modification to reduce the possibility of this event occurring again.

The operating EO round will include a check of this temperature switch until the mod is completed, s

Prepared by:

Johm M.

Damron