ML20084D221

AO 50-237/75-33:on 750526,torus Level Found to Be Low.Caused by Personnel Error.Water Pumped from Condensate Storage Into Torus Via HPCI Min Flow Line.Importance of Card Tagging Procedures Emphasized

ML20084D221
Person / Time
Site:	Dresden
Issue date:	06/05/1975
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
347-75, 6383, AO-50-237-75-33, NUDOCS 8304110008
Download: ML20084D221 (3)

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Mr. Jr.mos G. Keppler, Regional Director ,'

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SUBJECT:

REPORT OF AE70RMAL OCCURRE:CE PFR SFCTION 6.6.A OF THE TECHNICAL SPECIFICATIC'.;S UNIT-2 TC3US LO'I LEVEL

References:

1) Regulatory Guide 1.16 Rev. 1 Appendix A

2) Notification of Region III of U. S. Nuclear Regulatory Conrnosion Telephone: Mr. P. Johnson, 1600 hours0.0185 days <br />0.444 hours <br />0.00265 weeks <br />6.088e-4 months <br /> on May 27, 1975 Telegrcm: Mr. Keppler, 0o15 hours on May 27, 1975

3) Drawing N w.bor P & ID M-29 Report Ihunber: 50-237/1975-33 Report Date: June 5, 1975 Occurrence Date: May 26, 1975 Facility: Dresden Nucicar Power Station, Morris, Illinois ID2'TIFICATION OF OCCL'RRE!CE At 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br /> on May 26, 1975, the torus level was found to be -6".

, CONDITIONS _ PRIOR TO OCCURREICE . . .

Prior to the occurrence, unit-2 was in a steady-stato condition at 742 IGt and 206 F.de.

DESCRIPTION OF OCURRE;CE I

Decause control room torus level indication was unreliablo, visual inspections l of a sight glass at the torus woro being cndo once por shift. At 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br /> )

on May 26. 1975 the level was found to do 6".

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Mr. Jar.es G. Keppler, Re~ g ional Director - ' N T * ,,

Directorate of Regulatory Operation-Region III 7 ,, 7

' ' a U. S. Nuclear Regulatory Cnricaion 799 Roosevelt Road Glen Ellyn, Illincia 60137 kf[f .-

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SUBJECT:

REPORT OF AE;0RvAL OCCURRE CE PER SrCTION 6.6.A 0F THE TirEUCAL SPECIFICATIC'.;S UNIT-2 TC:lUS LOW LEVEL Referencea: 1) Regulatory Guide 1.16 Rev. 1 App'endix A

2) Notification of Regica III of U. S. Nuclear Regulatory Consnicsion Telephone: Fr. P. Johnson,1600 liours on May 27, 1975 Telegram: Mr. Keppler, OS15 hours on May 27, 1975

3) Drawing Number P & ID M-29 Report Number: 50-237/1975-33 s

Report Date: June 5, 1975 Occurrence Date: May 26, 1975 Facility: Drecden Nuclear Power Station, Morris, Illinois

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IDDITIFICATION OF OCCURRE*CE At 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br /> on May 26, 1975, the torus level was found to be -6".

CONDITIONS PRIOR TO OCCURRENCE Prior to the occurrence, unit-2 was in a steady-state condition at 742 Kit and 206 Mie.

DESCRIM' ION OF OCCURRE!CE Because control room torus level indication was urireliable, visual inspections of a sight glacs at the torus were being r.ade onco por shift. At 1700 hours0.0197 days <br />0.472 hours <br />0.00281 weeks <br />6.4685e-4 months <br /> on May 26, 1975 the level was found to be -6".

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p Junt 5, 1975 Q d DESIGNATION OF APPARE ?P CAUSE OF OCCURRE:CE (Procedural violation)

The apparent cause of the occurrence was the failure of station personnel to follow procedures. The first violation occurred when a "B" operator was unable to find LPCI header vent valves 2-1501-43B & 45B which had been tagged out-of-service during an outage. The operator assumed that ,

the 00S cards had either never been attached or were proviously removed.

The error was not caught, and the outage was subsequently cleared.

During LPCI system checks prior to start-up, valves 2-1501-433 & 45B were supposed to be used to vent T,he system drywell spray header. Another "B" operator was assigned this job. Apparently the operator inadvertently used the wrong valves because the two OOS cards again were not discovered.

This error left the LPCI header vent valves open with an impending unit startup. When the IICS jockey pu=p was started, water was pumped to the floor drain at the rate of approxw.ately 30 gpan.

ANALYSIS OP OCCURRE!CE The health and safety of plant personnel and the public were not jeopardized by this occurrence. In comparison to the system flow capability, the water volume lost through the 3/4" header vent lino was very small. A torus level of -6" represented a deviation of only 1/2" frcm Technical Specification limits. Given the conservative pressure and temperature calcu3ations for the torus, the loss of 1/2" vould not have affected the ability of the torus to perform in an emergency.

CORRECTIVE 1.CTION The imnediate corrective action was to start ptciping water from condensate storage into the torus via the HPCI minisnam flow line. At 1915 hours0.0222 days <br />0.532 hours <br />0.00317 weeks <br />7.286575e-4 months <br /> on May 26, torus level was at -5". By 0020 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> on May 27, the level was -3".

During this time an investigation was underway to determine the cause of the problcm. Heat exchanger tube leaks were suspected, as well as the piping line-up used earlier to pump uator from the torus to the condenser. During the corning of May 27, valves 2-1501-43B & 453 were found open with the OOS cards still attached. The valves were closed and the torus level promptly stabilized.

The importance of following 00S card tagging procedures has been re-emphasized to the operators involved. In addition, the 00S card tagging procedure is presently being revised to facilitate the accountability of 00S cards.

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[PtWl e B. Stephenson Superintendent BBS:s=p File /NRC l

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