05000298/LER-1982-018, Forwards LER 82-018/03L-0.Detailed Event Analysis Submitted

Forwards LER 82-018/03L-0.Detailed Event Analysis Submitted

ML20063K358
Person / Time
Site:	Cooper
Issue date:	08/26/1982
From:	Lessor L NEBRASKA PUBLIC POWER DISTRICT
To:	Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20063K360	List: 05000298/LER-1982-018, Forwards LER 82-018/03L-0.Detailed Event Analysis Submitted 05000298/LER-1982-018-03, /03L-0:on 820727,torus Water Temp Rose to 102 F, Exceeding Tech Spec Limit.Caused by Greater Bulk Temps During HPCI Test.More Sophisticated Torus Temp Monitoring Sys Will Be Installed by Jul 1983
References
CNSS820480, NUDOCS 8209030360
Download: ML20063K358 (2)

LER-1982-018, Forwards LER 82-018/03L-0.Detailed Event Analysis Submitted

Event date:
Report date:
2981982018R00 - NRC Website

text

_

s

'p.![]

^

COOPER NUCLEAR ST ATION 4

Nebraska Public Power District

"" " "'AT, %"#M;%%^1?^

t CNSS820480 August 26, 1982 a R@ BOW 1M*

Mr. John T. Collins, Regional Administrator l

!n#J /

3 0 l982 U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive if\\(

Q)

Suite 1000

~~

Arlington, Texas 76011

Dear Sir:

This report is submitted in accordance with Section 6.7.2.B.1 of the Technical Specifications for Cooper Nuclear Station and discusses a reportable occurrence that was detected on July 27, 1982. A licensee event report form is also enclosed.

Report No.:

50-298-82-18 Report Date:

August 26, 1982 Occurrence Date: July 27, 1982 Facility:

Cooper Nuclear Starion Brownville, Nebraska 68321 Identification of Occurrence:

A condition occurred which resulted in operation in a degraded mode permitted by a limiting condition for operation established in Section 3.7.A.1.C & D of the Technical Specifications.

Conditions Prior to Occurrence:

The reactor was at a steady state power of 100% of rated thermal power.

Description of Occurrence:

During the scheduled performance of Surveillance Procedure 6.3.3.1 (HPCI Test Mode Surveillance), torus (suppression pool) water temperature exceeded the limit of 100 F.

Designation of Apparent Cause of Occurrence:

The high torus water temperature was caused by the HPCI turbine exhausting into the torus.

r 2 7s

/#

k 8209030360 820826 PDR ADOCK 05000298 S

PDR

Mr. John T. Collins August 26, 1982 Page 2.

Analysis of Occurrence:

The HPCI System consists of a turbine driven pump which provides high pressure emergency core cooling for small line breaks. The steam turbine which drives the HPCI pump extracts steam from Main Steam Line "C" and exhausts steam into the torus for condensation.

Torus cooling is achieved by pumping torus water through the RHR (Residual Heat Removal) heat exchangers, where the heat is trans-ferred to the RHR service water system-(river water).

The water is returned below the torus water surface. Torus cooling had been initiated eight hours before the test and the torus water temper-ature had stabilized at 87 F.

The HPCI test mode surveillance was terminated af ter 15 minutes of operation when the torus water temperature reached 102 F.

Torus temperature was reduced to 100 F within fifteen minutes, and to 900F withir 145 minutes, by torus cooling. To satisfy testing requirements, the HPCI pump must be operated for a minimum of five minutes before recording required test data. Typically, the sur-veillance requires a minimum of ten minutes, and even longer when a complete set of vibration data is needed.

Despite torus water temperature indication of 102 F, conservative calculations show that the bulk torus water temperature could not have exceeded 97 F.

The existing torus water thermocouples are located downstream of the HPCI sparger near the surface of the water where highest water temperatures exist.

All safety systems were operable at the time of this occurrence.

This occurrence presented no adverse consequencea to the public health and safety.

Corrective Action

i Upon detection of the temperature violation, the surveillance test was terminated. A Technical Specification' change had'been prev-iously submitted to raise maximum allowable temperature an ad-ditional SOF which will lower the probability of recurrence. A more sophisticated torus temperature monitoring system'is scheduled to be installed by July 1983.

Sincerely, L. C. Lessor Station Superintendent Cooper Nuclear Station LCL:cg Attach.