ML20059D839
| ML20059D839 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 10/28/1993 |
| From: | Yandell L NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| References | |
| PNO-IV-93-031A, PNO-IV-93-31A, NUDOCS 9311030018 | |
| Download: ML20059D839 (2) | |
Text
October 28, 1993 q
y PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-IV-93-031A This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region IV staff on this date.
Facility Licensee Emergency Classification Texas Utilities Electric Co.
Notification of Unusual Event Comanche Peak 1 Alert Glen Rose,Texa.:
Site Area Emergency Dockets: 50-445 General Emergency X Not Applicable
Subject:
REACTOR COOLANT SPILL INSIDE CONTAINMENT (UPDATE)
On October 26, 1993, Comanche Peak Steam Electric Station (CPSES), Unit 1, was in the midst of a refueling outage with the core fully offloaded to the spent fuel pool and the reactor vessel drained down to below the steam generator nozzles to facilitate eddy current testing of two generators and other outage work. The refueling opender area'inside cc."ainment was flooded up to approximately 23 feet above the level of t;
'eactor vessel flange. A removable gate (the containment cavity lift gate) is equipped with a pneumatic seal and provided the boundary between the refueling water in the upender area and the refueling cavity.
At approximately 9:50 a.m. (CDT) on October 26, the pneumatic seal malfunctioned and approximately 18,000 to 20,000 gallons of refueling water spilled into the refueling cavity. The water then flowed into the vessel, through the coolant loops and out the open steam generator manways on Stcs Generators 1 and 4, to the containment floor and sump.
There has oeen no contaminated water released outside of containment. The seal malfunctioned when auxiliary, nonlicensed operators were in the process of switching the seal inflation pressure source from service air to a nitrogen bottle. At no time was the fuel stored in the spent fuel i
pool affected by this event.
Two steam generators were undergoing eddy current testing at the time, but no personnel were inside the generators. There were personnel in the steam generator compartments at the time, but no injuries or personnel contaminations occurred from this event.
Several minor shoe 1
contaminations did occur.
In a separate, but related event, an additional 4,000 gallons of water was sluiced from the upender area to the refueling cavity at about midnight on October 26.
This occurred when the licensee attempted to transfer the water remaining in the upender area to the refueling water storage tank (RWST).
Through a procedural deficiency, the operators opened two suction valves, thereby connecting the refueling cavity to the V
j upender area as well as establishing a flow path to the RWST. This t
i allowed about 4,000 gallons of water into the refueling cavity which ran
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PN0-IV-93-031A 4' to the open vessel, through the coolant piping and out the open steam generator primary manways. The operator in the control room noticed immediately that vessel level was changing, and the evolution was secured within 10 minutes.
Most of this water was caught in the catch containment that had been established from the previous event, and what little spilled over went to an area in the steam generator compartments that had not been decontaminated. This second event did not cause any personnel injury or personnel contamination.
At present, the upender area water level is 6 inches below the bottom of the containment cavity lift gate and the licensee has stopped all activities involving movement of primary water, pending the implementation of initial corrective actions.
Decontamination efforb have been underway for approximately 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, and in the most heavily contaiminated area close to the racks covering the containment sump, radiation dose rates are 2 to 6 millirad per hour.
This is down from readings of 30 to 40 millirads per hour initially.
In the general floor area, containmination surveys indicate 10,000 to 20,000 dpm/100 square centimeters, down from initial readings of 500,000 dpm/100 square centimeters.
No decontamination of the loop rooms has been completed at this time.
The licensee has formed a task team to evaluate these incidents, determine the root causes, and recommend corrective actions to management.
I Region IV has formed a special, multidisciplinau inspection team to follow up this event. The team began its initial activities the afternoon of October 26, 1993, and expect to complete onsite activities by November 3, 1993.
The state of Texas has been informed, i
Region IV has informed NRR, the ED0's office, and Public Affairs.
This information has been confirmed with a licensee representative as of 7 a.m., October 28, 1993.
Contact:
L. A. Yandell (817)860-8182 t
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