ML19354D736

LER 89-018-00:on 891123,hydrogen Dilution Blower 1-1 Casing Drain Line Broke Off at Casing,Declaring Blower Inoperable. Caused by Drain Line Being Accidentally Stepped On.Drain Removed & Pipe Plug installed.W/891222 Ltr

ML19354D736
Person / Time
Site:	Davis Besse
Issue date:	12/22/1989
From:	Storz L, Stotz J TOLEDO EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-018, LER-89-18, NP33-89-020, NP33-89-20, NUDOCS 9001020111
Download: ML19354D736 (4)

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..- .y TouEDO EDISON EDISON PLAZA 300 MADISON AVENUE TOLEDO. OHIO 43652 0001 December 22, 1989 Log No.: BB89-01339 NP33 89 020 Docket No. 50 346 License No. NPF-3 United States Nuclear Regulatory Commission

-Document Control Desk k'ashington, D. C. 20555 Centlemen:

LER 89 018 Davis Besse Nuclecr Power Station, Unit No. 1 Date of Occurrence - November 23. 1989 Enclosed please find Licensee Event Report 89-018 which is being provided in accordance with 10CFR50.73(a)(2)(1) to provide 30 days written notification of the subject occurrence.

Yours truly,

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Louis F. Storz Plant Manager Davis Besse Nuclear Power Station LFS/p1f Enclosure cc: Mr. A. Bert Davis Regional Administrator USNRC Region III Mr. Paul Byron DB-1 NRC Sr. Resident Inspector 9001020111 891222

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l On November 23, 1989, at 0500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br />, the flydrogen Dilution Blower 1-1 casing drain line broke off at the casing. The blower was declared inoperable.

Since flydrogen Dilution Blower 12 was previous.y declared inoperable for maintenance, the Station entered Technical Specification 3.0.3. This required restoration of at least one blower within one hour or initiation of a reactor shutdown. Under Immediate Action Maintenance 89-039 (MWO 1-89 2185-00),

Blower 1-l'was returned to operable status by 0550 hours0.00637 days <br />0.153 hours <br />9.093915e-4 weeks <br />2.09275e-4 months <br /> with the successful completion of the applicable portion of DB-SP-03320, flydrogen Dilution Blower System Train 1-1 Quarterly Test. This allowed the Station to exit Technical Specification 3.0.3. Temporary Modification 89-049 was written to justify plugging the drain line opening. The drain line failed when it was accidentally stepped on by an equipment operator. The line broke at the l threaded connection going into the casing. The area had been weakened by l corrosion on the outside of the threads from leakage through the threads.

1 The incidental contact event is viewed as random and not indicative of a reduction in the overall level of careful work practices.

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On November 23, 1989, at 0500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br />, the llydrogen Dilution Blower (BB) 1-1 casing drain line broke off at the casing. This caused the loss of seal water which required the blower to be declared inoperable. With the Ilydrogen Dilution Blower 1-2 already inoperable since. November 15, 1989, to allow repair of its seal water isolation valve, the Station was outside the action statement of Technical Specification 3.6.4.3. This required an entry into Technical Specification 3.0.3 whfch requires restoration to a condition covered by the 11 Dilution System action statement or the initiation within 2

one hour of action to shutdown the reactor by placing it in at least hot standby within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, at least hot shutdown within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and at least cold shutdown within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

The Hydrogen Dilution Blower 1 1 drain line opening was repaired and the blower declared operable by 0550 hours0.00637 days <br />0.153 hours <br />9.093915e-4 weeks <br />2.09275e-4 months <br />. Technical Specification 3.0.3 was exited before the initiation of shutdown was required.

This event is being reported under 10CFR50.73(a)(2)(1)(B) as a condition prohibited by Technical Specifications.

Annarent Cause of Occurrence:

The failure of the drain line occurred because it was accidentally stepped on by an equipment operator working around the equipment. The line failed at the threaded connection at the casing. The threaded area had been weakened by corrosion on the outside of the threads. The corrosion is from a tiny leak L path through the threads which slowly corroded the area.

1' Analysis of Occurrence:

The hydrogen dilution system consists of two full capacity blowers used to add air to containment to suppress the hydrogen volume fraction due to a LOCA.

The buildup of hydrogen is not expected tc reach any limits of concern prior to 21 days into a LOCA. The hydrogen dilution system would not be used until that time. Therefore, not having a hydrogen dilution system availabic for the short duration of this event does not present a significant safety concern.

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! Under Immediate t.ction Mainten..nce 89-039 J Mr.i n t e na nc e Woth Didet 1 89 2185 00), the broken drain line was. re moved and a pil e plug installed The blower was declared operabic at 0555 hours0.00642 days <br />0.154 hours <br />9.176587e-4 weeks <br />2.111775e-4 months <br /> with the succ < ns f ul c on.p l e t i on of the applicable portion of DB SP 03320, llydrogen Dilut lon blower Systen Train 1-1 Quarterly Test. The Station exited 'Iechnical Specification 30 3 Temporary Modification (TM) 89 0049 was written to just i f y the o;oiabilits of the blower with the drain plugged. This incident al cont ac t svent is view ( d u random and not indicative of a reduct ion in the over al: 1( vt i of c at e f ul work practices.

Failure Date The previous event of incidental contact was reported in 1.1.1: b' 000 The Swit ch f or a riiain f eedwat er 5t op valve was 1,uit:5+d out of 1.o s i : i oii c a o s i i .;- t 1.e valve to close which lead to a reactor trip REPORT NO. NP33-89-020 PC /cE . t 4 !dl mac eoa= 2 . . 5 om ne o e:4 saa 45 nw

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