05000298/LER-2004-003, Regarding High Pressure Coolant Injection Pump Inoperability Results in Loss of Safety Function
| ML042160012 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 07/27/2004 |
| From: | Minahan S Nebraska Public Power District (NPPD) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NLS2004090 LER 04-003-00 | |
| Download: ML042160012 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 2982004003R00 - NRC Website | |
text
N Nebraska Public Power District Always there when you need us NLS2004090 July 27, 2004 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington. D.C. 20555-0001 Gentlemen:
Subject:
Licensee Event Report No. 2004-003-00 Cooper Nuclear Station, NRC Docket 50-298, DPR-46 The purpose of this correspondence is to forward a Licensee Event Report.
Sincerely, twrB.Minahan General Manager of Plant Operations
/jrs Enclosure cc: Regional Administrator w/enclosure USNRC - Region IV Senior Project Manager w/enclosure USNRC - NRR Project Directorate IV-I Senior Resident Inspector w/enclosure USNRC NPG Distribution w/enclosure INPO Records Center w/enclosure SORC Administrator w/enclosure SRAB Administrator w/enclosure Records xv/enclosure COOPER NUCLEAR STATION P.O. Box 98 / Brownville, NE 68321-0098 Telephone: (402) 825-3811 / Fax: (402) 825-5211 www.nppd.comn
Abstract
At 1915 Central Daylight Time (CDT) on June 1, 2004, the control room received an alarm from the High Pressure Coolant Injection (HPCI) exhaust drain pot high-level sensor. This alarm had been occurring hourly or less because the turbine steam supply valve had been leaking. The alarm procedure directs that the exhaust drain pot be drained. This time, however, the alarm did not clear when other indicators revealed that the pot had drained. As precautionary measure, the HPCI system auxiliary oil pump was placed in pull to lock. This in turn resulted in the HPCI Pump becoming inoperable. HPCI remained available at all times. HPCI was returned to service at 1536 CDT on June 2, 2004.
This event is reportable in accordance with 10 CFR 50.73(a)(2)(v)(D) as 'Any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident."
The cause of the event was poor maintenance of the HPCI steam supply valve resulting in it leaking excessively. This, in turn, caused frequent cycling of the HPCI exhaust line drain pot level switch which became misaligned and failed to operate. The level switch was re-aligned and HPCI was declared operable on June 2, 2004 at 1536 CDT. The HPCI steam supply valve will be refurbished during the next refueling.
Preventive maintenance will be established to prevent excessive seat leakage in this valve.
NRC FORM 366 (7-2001)
(If more space is required, use additional copies of (if more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A)
PREVIOUS SIMILAR EVENTS
A number of instances of failures of the HPCI exhaust drain pot switch and previous leakage problems with the HPCI steam supply valve were found. Instances where the two events were linked were also noted. However, a specific plan to address reliability problems with the level switch by addressing the internal condition of the steam supply valve was not found. Because the safety function of the steam supply valve is to open and leakage through the valve did not affect this safety function, there was no impetus to link the two effects.
ATTACHMENT 3 LIST OF REGULATORY COMMITMENTSO Correspondence Number:
NLS2004090 The following table identifies those actions committed to by Nebraska Public Power District (NPPD) in this document. Any other actions discussed in the submittal represent intended or planned actions by NPPD. They are described for information only and are not regulatory commitments. Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory
commitments
COMMITTED DATE
COMMITMENT
OR OUTAGE Re-calibrate and align the HPCI exhaust line drain pot level 10/29/04 switch.
The appropriate maintenance plan will be revised to ensure 08/30/04 that it adequately addresses re-aligning the internal switch mechanism of the HPCI exhaust drain pot level switch.
Refurbishment preventive maintenance will be established to 10/21/04 prevent excessive seat leakage in the HPCI steam supply valve.
Determine if it is necessary to place the auxiliary lube oil 10/25/04 pump in the pull to lock position when the HPCI drain pot high level alarm does not clear.
Refurbish the HPCI steam supply valve.
RE22 4
4 4
4 S
J.
I PROCEDURE 0.42 l
REVISION 15 l
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