ML17335A330

LER 98-031-00:on 980610,potential Common Failure of RHR Pumps Occurred.Caused by Design Deficiency.Bypass Flow Testing Scheduled for All 4 Pumps to Confirm Adequate Flow. with 980710 Ltr

ML17335A330
Person / Time
Site:	Cook
Issue date:	07/10/1998
From:	Boston D, Sampson J AMERICAN ELECTRIC POWER CO., INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-98-031, LER-98-31, NUDOCS 9811160191
Download: ML17335A330 (2)

Text

United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Operating Licenses DPR-58 Docket No. 50-315 Document Control Manager:

In accordance with the criteria established by 10CFR 50e73 entitled Licensee Event Re ort

~Sstem, the following report is being submitted:

98-031-00 Sincerely, J.R. Sampson Site Vice President

/mbd Attachment c: C. J. Paperiello (Acting) Region III J. R. Sampson P. A. Barrett S. J. Brewer R. Whale D. Hahn Records Center, INFO NRC Resident Inspector

LICE EVENT REPORT (LER)

FACILITY NAME: Cook Nuclear Plant Unit 1 PAGE: 1 OF 1 DOCKET NUMBER: 05000315 TITLE: Interim LER - Potential Common Mode Failure of Residual Heat Removal Pumps Due to Original Design Deficiency EVENT DATE: 06/10/98 LER (): 98-031-00 REPORT DATE: 07/10/98 OTHER FACILITIES INVOLVED: DOCKET NO: 05000316 Cook Unit 2 OPERATING MODE: 5 POWER LEVEL: 0 THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR SECTION:

50.73(a)(2)(ii), 50.73(a)(2)( v)

LICENSEE CONTACT FOR THIS LER:

NAME: Mr. Dan Boston, Safety Related Mechanical Engineering Superintendent TELEPHONE: (616) 465-5901 ext., 1863 COMPONENT FAILURE DESCRIPTION:

CAUSE: SYSTEM: COMPONENT: MANUFACTURER:

REPORTABLE NPRDS:

SUPPLEMENTAL REPORT EXPECTED: Yes, 09/24/98 ABSTRACT:

On June 10, 1998, with both units in Mode 5, it was determined that the Residual Heat Removal (RHR) pump minimum flow (miniflow) controls for both units had a potential design deficiency. Westinghouse Nuclear Safety Advisory Letter (NSAL)98-002 stated that during a LOCA of a size to allow the RHR/Low Head Safety Injection pumps to inject into the reactor coolant system (R.C.S.) at less than required miniflow, the miniflow valves might cycle repeatedly from open to close until the valves or the valve motors failed.

Available miniflow is a combination of accident mitigation flow and bypass flow until the valves or the valve motors failed. Available miniflow is a combination of accident mitigation flow and bypass flow through the miniflow valves. If the failed valves prevented adequate miniflow, the associated RHR pumps could fail. In accordance with 10CFR50.72(b)(2)(I), "Any event, found while the reactor is shutdown, that, had it been found while the reactor was in operation, would have resulted in the nuclear power plant being in an unanalyzed condition that significantly compromises plant safety," and 10CFR50.72(b)(2)(iii), "Any condition that alone could have prevented the fulfillment of the safety function of a system needed to mitigate the consequences of an accident," an ENS notification was mad at 1140 hours0.0132 days <br />0.317 hours <br />0.00188 weeks <br />4.3377e-4 months <br /> EDT. This interim LER is therefore submitted in accordance with 10CFR50.73(a)(2)(ii) and 10CFR50.73(a)(2)(v).

During initial evaluation of this potential condition, review of historical miniflow instrument calibration data revealed variations in instrument response and control set points. These variations must be considered when determining which pumps are affected; therefore, evaluation of the potential condition is ongoing. Additionally, the review indicated that two pumps may have low bypass flow. Bypass flow testing has been scheduled for all pumps to conform adequate bypass flow, and testing of one Unit 1 pump has already been completed satisfactorily. An upgrade to this LER will be provide after completion of testing and evaluation, which is expected by September 24, 1998.

END OF ABSTRACT ATTACHMENT 1 TO 9811055555 PAGE 1 OF 1