ML19256C979
| ML19256C979 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 06/11/1979 |
| From: | Bryan S, Klingler G, Nolan F NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| References | |
| PNO-79-142, NUDOCS 7910150809 | |
| Download: ML19256C979 (2) | |
Text
,
f PRELIMINARY NOTIFICATION June 8, 1979 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-79-142 This preliminary notification constitutes EARLY notice of event of POSSIBLE safety or public interest significar.ce.
The information presented is as initially received without verification or evaluation and is basically all that is known by IE staff on this date.
Facility:
Ccmmonwealth Edison Company, Zion Unit 1 (DN 50-295) Zion, Illinois
Subject:
REACTOR TRIP - POTENTIAL FEEDWATER HA. TIER At 6:22 a.m. on June 8, 1979, Unit 1 tripped off line while operating at 100%
power. The reactor trip / turbine trip was initiated by low steam generator (S/G) level which was caused by the loss of one of the main feedwater pumps.
The auxiliary feedwater system functioned normally, as did other plant systems.
However, shortly after the trip and while the operator was throttling auxiliary feedwater flow to the "D" S/G, pipe vibrations were experienced on the S/G's, the worst of which occurred on the A S/G.
Also during this period, the A S/G loop Delta P Safety Injection (SI) actuation alarm was received; apparently caused by the vibrations, however, SI did not initiate automatically. As a result, the operator manually initiated SI per procedural requirements, and all systems functioned normally.
SI was terminated by operator action af ter 1 3/4 minutes, when it was determined not to be needed.
The pressurizer level and pressure, and the steam generator levels remained within acceptable levels during this event.
The plant is being maintained in hot shutdown, and plant systems are functioning normally.
This matter will be thoroughly investigated by the licensee and all problems will be corrected prior to returning the unit to service.
These actions include:
1.
Visual inspection of the main steam and feedwater piping to verify no damage occurred.
All of this piping outside containment has been inspected, and no abnormalities were found.
2.
The problem with the feedwater pump will be determined and corrected.
It appears that the pump trip was caused by receipt of a thurst bearing alarm.
3.
The problem with the SI actuation will be determined and corrected.
Surveillance testing will be performed.
A similar SI event was experi-enced previously, and during that event, the cause was shown to be a spurious pressure igike of short duration caused by the close proximity of the pressure sensors to the feedwater lines. For this event the computer printout shows that the pressure spike lasted less than one cycle, which is of sufficient duration to actuate the solid state alarm, but not the actuation relay.
CONTINUED 1450 178 (1) r)
qs10150 t
Continued June 8, 2979 Page 2
- PNO-79-142 The IE Resident Inspector will verify the adequacy of the licensee's actions prior to startup of the unit.
The State of Illinois has been notified.
Neither the Licensee nor RIII are planning on issuing a press release at this time.
Region III (Chicago) was informed of this event by the licensee at 9:00 a.m.
on June 8, 1979.
Contact:
GKlingler, IE x20019 FNolan, IE x28019 SEBryan, IE x28019 TransmittedHSt5f.hL Distribution:
Chairman Hendrie Commissioner Bradford S. J. Chilk, SECY Commissioner Kennedy Commissioner Ahearne C. C. Kammerer, CA Commissioner Gilinsky ACRS (For Distribution) h ' 4.,))
I r
it t
j Transmitted:
MNBB.-8, P. Bldg M
_L ( ~
J. G. Davis, IE L. V. Gossick, EDO H. R. Denton, NRR Region 1 l
H. L. Ornstein, EDO R. C. DeYoung, NRR J. J. Fouchard, PA R. J. Mattt.on, NRR N. M. Haller, MPA V. Stello, NRR (MAIL)
R. G. Ryan, OSP R. S. Boyd, NRR.
J. J. Cummings, OIA H. K. Shapar, ELD SS Bldg 4 !! ;
R. Minogue, SD W. J. Dircks, NMSS S. Levine, RES PRELIMINARY NOTIFICATION 1450 @
.