ML19290A430

Environ Event Rept 76-28/4T:on 760827,plant Discharge Water Temp More than 3 F Less than River Water Inlet Temp.Caused by Thunderstorm Activity.Temp Differential Restored.Ets & Federal Power Commission Requirements to Be Evaluated

ML19290A430
Person / Time
Site:	Three Mile Island
Issue date:	08/20/1976
From:	Arnold R METROPOLITAN EDISON CO.
To:
References
GQL-1194, NUDOCS 7911070609
Download: ML19290A430 (4)

Text

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FROG oATt or DOCUMENT Me tropolitan Edison Company 8/20/76 Mr. J. P. O'Reilly Reading, Penna. DATE HCCElVEO Mr. R. C. Arnold 8/30/76 U N O'T O R IZ E D PROP INPUT FORM NUMDER OF COPIES HECElvt;U XtcTTc n

)(OH IGIN A L p[WNC LASst FIE D One signed OCOPY CCScalPTION ENCLOSURE Ltr. furnishing Licensc:e Event Report (ER 50-289/76-28/4T) on 8/13/76 concerning the plant

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discharge water temperature being more than 3 degrees F less than the river water inlet tempera ture.

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PLANI NAME:

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August 20, 1976 m g_ N GQL 119h ,

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r Mr. J. P. O'Reilly, Director y* h 'N Office of Inspection & Enforcement, Region I

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Dear Sir:

Docket No. 50-289 Cperating License No. DPR-50 In accordance with the Technical Specifications of our Three Mile Island Nuclear Station Unit 1 (TMI-1), we are reporting the following reportable occurrence:

(1) Report Number: ER 76-28/hT (2a) Required Report Date: August 27, 1976 (2b) Date of Occurrence: August 13, 1976 (3) Facility: Three Mile Island Nuclear Station - Unit 1 (L) Identification of Occurrence:

Title:

Violation of the Envircnmental Technical Specifications, paragraph 2.1.a {l) in that the plant discharge water temperature was more than 3~F less than the river water inlet temperature.

? fpe: This event is considered to be a reportable occurrence as defined in the Appendix 3 of Technical Scecifications, paragraph 5.6.2C.

1557 289 I

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Mr. J. P. O'Reilly, Director August 20, 1976 GQL 119h (5) Conditions Prior to occurrence Power: Core 1005 Elec. 820 ige RC Flow: 138 x 106 #/hr.

RC Pressure: 2155 PSIG RC Temp: 579 F PRZR Level: 225 inches PRZR Temp: 650 F (6) Description of Occurrence:

The river water temperature as monitored on the computer was 78.h F during the period 1700 to 1900 on August 13, 1976. The Control Room 0

operator was maintaining the AT recorder at approximately -2.0 F AT to maintain the plant effluent temperature less than the plant inlet temperature. A severe thunderstorm which accompanied a cold front moving through the area during the same period caused the local ambient air temperature to sharply drop frc= approximately 83 0F to 72 F in twenty (20) minutes. In i==ediately responding to the relatively sudden temperature changes, the operator was unable to anticipate nor turn around the sharp drop in effluent temperature. As a result the AT exceeded -3 0 F for nearly thirty (30) minutes with a maximum of h.00F AT.

When the cool air passed the AT rose within the -3.0 F limit and the operator regained control of the AT by restarting the fans as appropriate.

(7) Designation of Apparent Cause of Occurrence:

This occurrence was caused by the inability to anticipate ambient air temperature changes due to the thunderstor= activity in the area and the resultant abrupt changes in Mechanical Draft Cooling Tower cooling characteristics. This was further aggravated by a Federal Power Co =ission requirement to maintain the AT between 0 F and -3.0F at all times.

(8) Analysis of Cccurrence:

It is believed that the maximum negative temperature differential of h.0*F did not cause any environmental damage in that the conditicn lasted cnly a short time and was not so severe as to greatly alter the ambient temperature of the river.

1557 290

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Mr. J. P. O'Reilly, Director August 20, 1976

, GQL 119h

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(9) Corrective Action:

E<2tEDIATE: The only immediate corrective action taken was to restore the temperature differential to within the allovable range by enanging the cooling tower fan combination.

LONG TERM: A change to the Envirennental Technical Specifications and the Federal Power Conmission Requirements vill be evaluated to determine whether shcrt term departures from the -3.0 F AT along with appropriate action levels would provide adequate environmental protection. This change would provide the necessary operational flexibility while complying with the true spirit of the Environmental Technical Specifications during such environmental transients.

(loa) Failure Data: Not Applicable (10b) Similar Occurrences :

EI Th-1 EI Th-8 EI 75-7 EI 75-8 Sincerely, f

m R. C. ARNOLD RMK:JJM:mo I557 291