ML20012D262
| ML20012D262 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 03/20/1990 |
| From: | Johnson W, Joel Wiebe NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| References | |
| PNO-ADSP-90-007, PNO-ADSP-90-7, NUDOCS 9003270114 | |
| Download: ML20012D262 (2) | |
Text
y 4
March 20, 1990 c
0 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-ADSP-90-07-A l
This preliminary notification constitutes EARLY notice of events of POSSIBLE l
safety or.public interest significance.
The information is as initially received without verification or evaluation, and is basically all that is known by the ADSP staff on this date.
FACILITY:
TV Electric Licensee Emergency Classification:
Comanche Peak Unit 1 Notification of Unusual Event Docket No. 50-445 Alert Glen Rose, Texas Site Area Emergency General Emergency X
Not Applicable
SUBJECT:
COMANCHE PEAK UNIT 1 - AUGMENTED INSPECTION TEAM UPDATE p
I An AIT was dispatched to Comanche Peak Unit I to review a Maren 12, 1990 event in which an inadvertent actuation of Train A safety injection (SI) occurred i:
~
with the unit in MODE 4.
On March 17, 1990, the AIT completed the onsite inspection and the AIT exit interview was conducted on March 19, 1990.
Key elements of the AIT charter were to develop a thorough technical understanding of plant and operator response to this event, to determine expected consequences
' of the event had it occurred at full power, and to review the licensee's
. investigation of the event.
During this review, the AIT confirmed the licensee's conclusion that the cause of the event was a shorted blocking diode in the Train A SI logic circuitry which allowed a containment ventilation isolation signal to back feed and initiate Train A SI components.
The containment ventilation isolation signal was generated as expected by routine maintenance i
on a radiation monitor.
f The licensee assembled an evaluation team on the day of the event to review t
the event and recommend corrective actions.
Initial corrective actions required by the licensee's onsite Operations Review Committee for entry into MODE 4 4
-1 have been completed and the unit is presently in MODE 4.
Actions required for entry into MODE 3 are in progress and include implementation of a design change to correct auxiliary feedwater (AFW) flow control problems which occurred during the event as a result of the low steam generator pressure.
Preliminary licensee reviews along with preoperational test data show that at higher steam generator pressure, the flow control problems do not occur and.
the operability of the AFW system would not have been compromised. Although
- the Train A AFW components actuated as designed during the event, AFW is not required to be operable until MODE 3.
The AFW modification is being reviewed by the Comenche Peak Project Division.
. Preliminary conclusions from the AIT are that the licensee conducted a thorough review of this event, operator response was good, and the same event at full power is bounded by plant safety analysis.
The SI logic design with the single blocking diode is believed to be a standard Westinghouse design and 9003270114 900320 PDR I&E t
PNO-ADSF<f 99907 PDC 0 t i
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.4-an Information Notice is being recommended.
The AIT report with final conclusions and recomendations will be issued in 30 days.
The Comanche Peak Project Division will monitor licensee actions from the licensee's evaluation team findings.
A press release was. issued from NRC Region IV regarding the AIT on March 15,_
1990.
Local media interest continues and is being responded to by the licensee and the NRC.
The State of Texas has been informed.
CONTACT:
J. S. Wiebe (817) 897-1500 W. D. Johnson (817) 897-1500 DISTRIBUTION:
One White Flint North MNBB Regions Mail To:
Chairman Carr TRR-Region I ACRS Com Roberts OIG Region II Com. Rogers AEOD Region III Fax To:
Licensee (Corporate)
Com. Curtiss Region IV Resident Inspector Com. Remick Region V SECY OGC Nicholson Lane OCA RES GPA/SLITP/PA EDO-DI NRR NMSS t
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