Morning Report for April 13, 2000

                       Headquarters Daily Report

                         APRIL 13, 2000

                    REPORT             NEGATIVE            NO INPUT
                    ATTACHED           INPUT RECEIVED      RECEIVED

REGION I            X
REGION II                              X
REGION III                             X
REGION IV                              X

Licensee/Facility:                     Notification:

                                       MR Number: H-00-0025
Sequoyah Unit 1                        Date: 04/13/00

Subject: Update--March 14, 2000; Loss of Reactor Coolant Inventory
         at Sequoyah Unit 1


This is a supplemental Morning Report to provide a detailed account and a
safety assessment of the subject event.

On March 13, 2000, Sequoyah Unit 1 was in shutdown condition Mode 5,
making preparations to transition to Mode 4 at the conclusion of the
refueling outage. The reactor coolant system (RCS) was at 360 psig and
145F with pressurizer (PZR) level at 76 percent. At 11:51 p.m., operators
initiated a procedure to vent the residual heat removal (RHR) discharge
piping with the RHR pump running. The operators expected a pressurizer
(PZR) level drop of up to 15 percent. When the PZR level continued to
decrease beyond the expected amount, the operators entered an abnormal
operating procedure to stabilize the unit. The recovery actions were
effective and by 12:57 a.m. the operators stabilized the unit in Mode 5
at 130 psig and 145F with pressurizer level at 40 percent. The licensee
estimates that 10,000 gallons of reactor coolant were discharged to the
pressurizer relief tank (PRT) during the event. About half that volume
overflowed onto the primary containment floor when the PRT's available
capacity was exceeded, and the PRT rupture disc opened.

The unanticipated decrease in pressurizer level was caused by the failure
of a relief valve in the RHR pump discharge flow path to reseat promptly
following its inadvertent actuation. The actuation was caused by a
pressure pulse that occurred when operators redirected RHR flow with a
running pump and partially voided lines. Subsequent testing of the relief
valve confirmed that the valve lifted as designed at approximately 600
psig. The lowest observed PZR level was 11 percent and operators were not
required to start a second charging pump or any other emergency core
cooling system (ECCS) equipment to recover PZR level. The relief valve
was isolated and replaced following the event. Since the relief valve
could be isolated, the potential for continued loss of inventory during
the event was very low. In addition, the other train of RHR shutdown
cooling was available had it been required. The licensee's investigation
continues about why the valve failed to reseat promptly.

Initially this event was reported as a Loss of Coolant Accident. However,
at the time of the event, the reactor had been in a shutdown condition
for three weeks and the RCS pressure was at a fraction of the operating
pressure. The event was a reactor coolant loss of inventory due to an
inadvertent relief valve actuation, which could be isolated using
available valves. The reactor coolant was contained in the primary
containment. The event did not result in any offsite releases and had no
impact on the public health and safety.

Robert A. Benedict, NRR/REXB        Paul E. Fredrickson, Region II
          301-415-1157              404-562-4530
HEADQUARTERS      MORNING REPORT     PAGE  2          APRIL 13, 2000
MR Number: H-00-0025 (cont.)

          E-mail:      E-mail:

REGION I  MORNING REPORT     PAGE  2          APRIL 13, 2000

Licensee/Facility:                     Notification:

                                       MR Number: 1-00-0007
Christiana Care Health System          Date: 04/13/00
Dockets: 03001303 License No: 07-12153-02



On April 12, 2000, the RSO at Christiana Care Health System, Wilmington,
Delaware, informed the NRC Region I office that an individual died at
home who had previously been implanted with iodine-125 seeds.  The
current activity is estimated to be 12 millicuries.  The body is to be
cremated.  The RSO said that he will tell the family to inform the
mortician and crematorium's staff that the body still retains iodine
seeds.  Also, although not required, since the individual had been
released from the Medical Center, in accordance with 10 CFR 35.75
requirements, the RSO said that after the cremation, he will perform a
survey at the crematorium and recover the seeds for appropriate disposal.

Regional Action:

No further action is required by the Region.

Contact:  Teresa Hall Darden         (610)337-5245
          Mohamed M. Shanbaky        (610)337-5209

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