ML20003B078

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Forwards LER 81-007/03T-0
ML20003B078
Person / Time
Site: Fort Saint Vrain Xcel Energy icon.png
Issue date: 02/03/1981
From: Warembourg D
PUBLIC SERVICE CO. OF COLORADO
To: Seyfrit K
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20003B079 List:
References
P-81038, NUDOCS 8102100329
Download: ML20003B078 (6)
v • d • e


Text

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pubuc sendee company oe odende 16805 ROAD 19%

PLATTEVILLE, COLOR ADO 80651 February 3,1981 Fort St. Vrain Unit No. 1 P-81038 Mr. Karl V. Seyfrit, Director Nuclear Regulatory Comission Region IV Of fic.e of Inspection and Enforcement 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76012

Reference:

FaciI tty Operating License No. DPR-34 Docket No. 50-267

Dear Mr. Seyfrit:

Enclosed please find a copy of Reportable Occurrence Report No. 50-267/

81-007, Final, submitted per the requirements of Technical Specification AC 7. 5. 2 (a)2.

Also, please find enclosed one copy of the Licensee Event Report for Reportable Occurrence Report No. 50-267/81-007.

Very truly yours,*

Don Warembourg -

Manager, Nuclear Production DW/cis Enclosure cc: Director, MIPC 0

Mi g snos1o,,3g9

REPORT DATE: Februarv 3, 1981 REPORTABLE OCCURRENCE 81-007 Determined ISSUE O OCCURRENCE DATE: Januarv 20, 1981 Page 1 of 5 FORT ST. VRAIN NUCLEAR CENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO 16805 WELD C01.TIY ROAD 191/2 PLATTEVILLE, COLORADO 80651 REPORT No. 50-267/81-007/01-T-0 Final IDENTIFICATION OF OCCURRENCE:

On Tuesday, January 20, 1981, while evaluating PCRV cooling water system temperature data in preparation of a reportable occurrence for a degraded mode of LCO 4.2.15(e), it was determined that the minimum average of the inlet and outlet cooling water temperatures in Loop 2 were less than 100*F from approximately 0400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br /> on January 8, 1981, until approximately 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br /> on January 10, 1981.

This event is reportable per Fort St. Vrain Technical Specification AC 7.5.2(a)2.

CONDITIONS PRIOR TO OCCURRENCE:

Cold shutdotm.

THE MAJOR PLANT PARAMETERS AT THE TIME OF THE EVENT L' AS FOLLOWS:

Reactor Power 0 .W" .o%

Primary Coolant Pressure 300 7sIA 300 PSIA Temperature Circulator Inlet 85*F 4

Temperature Core Outler 120*F Total Flow 144,000 f/hout 4.1%

Secondary Coolant Pressure 232 PSIG Temperatura 111* F Flow 176,000 #/ hour, 7.7%

- Electrical 0 MWe, 0.0%

REPORTABLE OCCURRENCE 81-007 ISSUE O Page 2 of 5 DESCRIPTION OF OCCURRENCE:

At 0430 hours0.00498 days <br />0.119 hours <br />7.109788e-4 weeks <br />1.63615e-4 months <br /> on January 8,1981, the average of the inlet and outlet water temperature of the PCRV liner cooling system Loop 2 decreased below 100*F.

At 2330 hours0.027 days <br />0.647 hours <br />0.00385 weeks <br />8.86565e-4 months <br /> on January 8, 1981, the Loop 1 average also dropped below 100*F. Loop 1 increased to 100*F at 0415 hours0.0048 days <br />0.115 hours <br />6.861772e-4 weeks <br />1.579075e-4 months <br /> on January 9,1981.

Loop 2 increased to 100*F at 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br /> on January 10, 1981.

Fort St. Vrain Technical Specification LCO 4.2.15 states "The temperature of the PCRV cooling water system shall be maintained within the limits stated below, irrespective of whether the reactor is operating or shutdown:"

One of the limits states; "The minimum average of the inlet and outlet cooling water temperatures shall be greater than or equal to 100*F."

  • No time limit is specified in LCO 4.2.15; however, Section 4.0 of the Tech-nical Specifications allows a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period for correction of an LCO vio-lacion if no other tims limit is specified.

1 The Loop i event, corrected within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, constitutes operation in a de-graded mode allowed by an LCO and is reported as such in accordance with Section AC 7.5.2(b)2 of the Fort St. Vrain Technical Specifications.

The Loop 2 event extended for more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and constitutes operation of a system with a parameter subject to a limiting condition less conserva-tive than the least conservative aspect of the limiting condition for oper-acion established in the Technical Specifications. This event is reported in accc rdance with AC 7.5.2(a)2 of the Fort St. Vrain Technical Specifi-cations.

APPARENT CAUSE OF OCCURRENCE:

Personnel error.

ANALYSIS OF OCCURRENCE:

The reactor was shutdown on December 31, 1980, and cooled down to approxi-mately 115'F on January 1, 1981. Ths primary coolant temperature was re-duced further on January 6,1981, to about 100*F, and on January 7,1981, . co approximately 80*F.

REPORTABLE OCCURRENCE 81-007 ISSUE O Page 3 of 5 ANALYSIS OF OCCURRENCE: (Cont'd)

During shutdown conditions, the PCRV liner cooling system continues to remove heat from et.e PCRV, but the heat removal rate is reduced by warming the inlet water with steam coils in the surge tanks.

The cooling water side of the PCRV liner cooling heat system heat exchanger was isolated on January 2, 1981, to reduce system heat loss, and steam was placed on the surge tank January 3, 1981. Because of pri=ary coolant temp-eratures, there was little, if any, heat transfer to the PCRV cooling system from that sosrce, 4:4 after the reduction on January 7, 1981, there may have been some heat loss to the primary coolant.

The Technical Specificacicu LCO 4.2.15 places limits on the PCRV cooling water temperature in order to maintain the PCRV integrity. One of these limits requires that the average of the inlet and outlet cooling water temp-erature be greater than or equal to 100*F to ensure liner operation above the fracture transition elastic temperature. ,

The average of the PCRV liner cooling system Loop 2 inlet and outlet water temperature was 101.25'F at 0000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> on January 8,1981, but was decreasing and went below 100*F at approximately 0430 hours0.00498 days <br />0.119 hours <br />7.109788e-4 weeks <br />1.63615e-4 months <br />. Loop 1 average temperature was 100*F at 2200 hours0.0255 days <br />0.611 hours <br />0.00364 weeks <br />8.371e-4 months <br /> January 8,1981, but was below 100*F at about 2330 hours0.027 days <br />0.647 hours <br />0.00385 weeks <br />8.86565e-4 months <br />.

It is not possible to determine if the cooling water system temperature decrease was due to increased heat loss from the system or decreased heat input via the surge tanks. Probably, the decrease below 100*F resulted from a combination of these causes.

At 0130 hours0.0015 days <br />0.0361 hours <br />2.149471e-4 weeks <br />4.9465e-5 months <br />, January 9,1981, the out of limit condition was noticed by an operator, and the steam supply to the surge tank heating coils was in-crease d. The increase in system heat input was sufficient to bring loop 1 inlet and outlet water temperature average back above 100*F by approximately 0415 hours0.0048 days <br />0.115 hours <br />6.861772e-4 weeks <br />1.579075e-4 months <br /> on January 9, 1981.

Loop 2, however, was colder (average = 96.25*F, the lowest temperature reached) and had been below 100*F for about 21 hours2.430556e-4 days <br />0.00583 hours <br />3.472222e-5 weeks <br />7.9905e-6 months <br /> by the time the heat input was increased. The increase in steam supply increased the average temperature, but not sufficiently to bring it back above 100*F within the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> al-lotted by the LCO. Loop 2 continued to operate with an inlet water, outlet water temperature average below 100*F until 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br /> on January 10, 1981.

Loop 1 was below 100*F for about 4.75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> while Loop 2 was below 100*F for about 53.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.

I

REPORTABLE OCCL'RROiCE 81-007 I ISSL'E O Page 4 of 5 CORRECTIVE ACTION:

The Loop 1 degraded condition was corrected by increasing the steam supply pressure to the system surge tanks.

The Loop 2 condition was corrected when the average water temperature in-creased abovs 100*F. No specific cause for the correction can be. identified.

Correct cperation of the PCRV liner cooling system during all conditions will be reviewed with all Licensed Operators by the Training Department.

A request has been sent to the Nuclear Project Department to traluate the effects, if any, on the PCRV top head liner material as a result of the low cooling water temperature in Loop 2.  !

No further corrective action is anticipated or required.

FAILURE DATA /SIMILAR REPORTED OCC'JRRE' ICES:

None PROGRAMMATIC IMPACT:

None CODE IMPACT:

None G

. e REPORTABLE OCCtIRENCE 81-007 ISSLT 0 Page 5 of 5 Prepared By: $ff{ k, M Richard R. Fros:

Technical Services Technician Revie>ed By: ./

. f. Gahn Itchnical Services Supervisor 4 Reviewed By:

Frank M. Mathie Operations Manager Approved By: 7[h Don Warembourg #

Manager, Nuclear Production 4

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