United States Nuclear Regulatory Commission - Protecting People and the Environment

Morning Report for Macrh 20, 2000

                       Headquarters Daily Report

                         MARCH 20, 2000

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                    REPORT             NEGATIVE            NO INPUT
                    ATTACHED           INPUT RECEIVED      RECEIVED

HEADQUARTERS                           x
REGION I            x
REGION II                              x
REGION III                             x
REGION IV                              x

PRIORITY ATTENTION REQUIRED  MORNING REPORT - REGION I  MARCH 20, 2000


Licensee/Facility:                     Notification:

Connecticut Yankee Atomic Power Co.    MR Number: 1-00-0004
Haddam Neck 1                          Date: 03/20/00
Hartford,Connecticut
Dockets: 50-213
PWR/W-4-LP

Subject: BACK WASH TANK OVERFLOW

Discussion:

On March 16, 2000, approximately one hundred gallons of reactor cavity
water overflowed through the cavity water filtration vent drum onto the
charging floor inside containment and down to the mid and lower
elevations of two loop areas.  The system was shut down and all cutting
in the reactor cavity was suspended.  The vent drum was associated with a
500 hundred gallon back wash tank that apparently overfilled.  System
evaluations, modifications and area decontamination occurred over the
weekend.

On March 20, 2000, the licensee resumed filtration operations after
modifications to prevent tank overflow and remediation of the charging
floor.  Although the event could not be recreated, two system
modifications (a vent pipe for drainage directly to the reactor cavity
and a back wash tank level trip) were made.  Human error was considered
highly unlikely since no workers were observed at the computer station to
open the valves.

An NRC inspector has been onsite since March 19, 2000 to observe the
licensee's follow-up to this event as part of a routine inspection as the
licensee continues its decommissioning activities.  There were no
personnel contaminations, no internal doses, and no radioactive releases
to the environment as a result of this event and subsequent remediation
activities.


Regional Action:

Regional Inspection

Contact:  S. Shaffer                 (610)337-5256
          R. Bellamy                 (610)337-5200
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