ML19312E214

Environ Event Rept 80-01:on 800501,daily Average Discharge Temp Exceeded Ambient River Water Temp by 5.7 F While Two Cooling Towers Were Undergoing Insp,Cleaning & Repair.One Tower Returned to Svc & Electrical Load Reduced

ML19312E214
Person / Time
Site:	Prairie Island
Issue date:	05/30/1980
From:	Ward E NORTHERN STATES POWER CO.
To:
References
NUDOCS 8006030479
Download: ML19312E214 (1)

Text

NSF NORTHERN STATES POWER COMPANY M 8 N N E A PO Li ts. M I N N E S OTA 55401 May 30, 1980 Mr J G Keppler, Director, Region III Office of Inspection & Enforcement U S Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137

Dear Mr Keppler:

PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket No. 50-282 License No. DPR-42

.50-306 DPR-60 Environmental Event Report 80-01 Maximum Discharge Temperature - TS B-2.2.1 Under TS B-5.4.2A, we are required to report as an Environmental Event when a protection condition is exceeded. According to TS B-2.2.1, the daily average circulating water temperature shall not exceed the ambient river water temperature by more than 5 F at the point of discharge to the river for river temperatures greater than 45 F.

On May 1, 1980, the daily average discharge temperature exceeded the ambient river water temperature by 5.7 F. ';he event occurred because cooling towers were being inspected, cicaned and repaired.

For a period of about four hours, two cooling towers were out )f service.

One tower was out for routine inspection and cleaning and the second for an emergency shutdown because of a header failure. This allowed the discharge water temperature to rise sufficiently to create the daily average excess of 0.7 F over the allowable dif ference. After observing excessive hourly temperature rises, the corrective action taken was to terminate cleaning one cooling tower and put it back into service and reduce electrical load on both generating units in an attempt to compensate for the slightly ex-cessive water temperature difference. Taking into account the modest extent  !

and duration of the excess water temperature condition, no significant j environmental impact resulted.

The cooling tower header failure created an immediate problem of reduced cooling efficiency. Usually cooling tower inspection and repair in May doesn't create excessive water temperature problems; however, this was complicated by the unseasonably high air temperature and low wind speed condition that persisted for several days.

Yours very truly, s

E C Ward , PE Manager-Nuclear Environmental Services cc: Director, NRR c/o DSB(17)

MPCA Att : J W Ferman

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