ML20236U914

PN-75-093:on 750918,RCS Inadvertently Pressurized from 90 Psig to Approx 1300 Psig Over 5 Minute Period.Licensee Has Committed to Remain in Cold Shutdown.Inspector Dispatched to Determine Cause & Review Analysis of Event

ML20236U914
Person / Time
Site:	Zion File:ZionSolutions icon.png
Issue date:	09/19/1975
From:	Jennifer Davis, Thornburg H, Warnick R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
To:
References
PN-75-093, PN-75-93, NUDOCS 9807310174
Download: ML20236U914 (1)

Text

- _ - _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ ___ _ _ _ . ._ - _ - - _ _ - -

PRELIMINARY NOTIFICATION - NOT FOR PUBLIC DISCLOSURE September 19. 1975 ,

p'p., -~-

PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE --PN-75-93

..e ,

This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information presented is as initially received without verification or evaluation and is basically all that is known by OIE staff as of 10:00 a.m. on the date of this notification. IT SHOULD BE SPECIFICALLY NOTED THAT THIS NOTIFICATION MAY CONTAIN INFORMATION THAT LATER MAY BE DETERMINED TO BE INACCURATE OR INCONSISTENT. AN OFFICE OF INSPECTION AND ENFORCEMENT

-. NOTIFICATION OF AN INCIDENT OR OCCURRENCE (BLUE SHEET) SUBSEQUENTLY WILL BE ISSUED IF WARRANTED.

--*s .. .

Facility: Commonwealth Edison Company (Zion Unit 2)

Subject:

OVER PRESSURIZATION OF REACTOR COOLANT SYSTEM At 1255 hours0.0145 days <br />0.349 hours <br />0.00208 weeks <br />4.775275e-4 months <br /> on September 18, 1975, the reactor coolant system was inadvertently pressurized from 90 psig to approximately 1300 psig over a 5 minute period. The reactor was in cold shutdown at the time. Incore thermocouple indicated coolant temperature to be 1100F. The licensee was performing a 20 month surveillance test on the Residual Heat Removal System (RHR) valve interlock. ' During the test the RER valve closed as designed isolating the RER letdown system M from the Chemical Volume Control System with the charging pump still ,

operating, The licensee has committed to remain in cold shutdown  !

~

( until the consequences of the incident are evaluated to determine if the vessel NDTT was approached.

[

This is the second overpressurization event at the Zion facility in 3 months. On June 4 the Unit 1 vessel pressure increased to 1200 psig.

The licensee's evaluation of that event concluded that system integrity had not been compromised.

6, An inspector has been dispatched to the site to determine the cause of the event and to review the licensee's analysis of the event and their f'

corrective actions to prevent recurrence.

8' Region III received notification of this occurrence by telephone from F Commonwealth Edison at 1508 hours0.0175 days <br />0.419 hours <br />0.00249 weeks <br />5.73794e-4 months <br />, September 18, 1975. O!

Contact:

RFWarnick, IE x7261 HDThornburg,, IE x7353 JGDavis, IE x7541 k

s 0* $ q y& Distribution: . .

S. J. Chilk, SECY g Chairman Anders Commissioner Mason Commissioner Gilinsky Commissioner Rowden G. F. Murphy, JCAE 8

Com=issioner Kennedy C. C. Kammerer, CA o

N n M L. V. Gossick, EDO

'$dU n D. F. Knuth, IE J. A. Harris, PA T. J. McTiernan, AIA O B. C. Rusche, NRR U K. R. Chapman, NMSS H. H. Brown, ISP H. K. Shapar, ELD ch b

( 10$d  ; Luge e _ d N Transmitted: P Bldg 12.h ; H St n MNBB / d, 1 l

PRELIMINARY NOTIFICATION - NOT FOR PUBLIC DISCLOSURE 1

- _ _ _ _ - - ____ _ l