ML19269D291
| ML19269D291 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 04/11/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Johari Moore SOUTHERN CALIFORNIA EDISON CO. |
| References | |
| NUDOCS 7904260168 | |
| Download: ML19269D291 (1) | |
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REClON V SUITE 202, W AtNUT C REEK PLAZ A
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W ALNUT CREEK, C ALIFORNI A 94596 April 11, 1979
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Docket Nos. 50-206
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50-361 50-362 Southern California Edison Company P. O. Box 800 2244 Walnut Grove Avenue Rocemead, California 91770 Attention: Mr. J. B. Moore Vice President Gentlemen:
In accordance with our letter dated April 1,1979 transmitting Bulletin 79-05, we are enclosing Preliminary Notification 79-77(NRR).
Sincerely, (OCT5~,.cCC.-
R. H. Engelken Director Enclosure PNO-79-77(NRR) cc w/ enclosure:
r J. M. Curran, SCE la J. T. Head, SCE 3
J. H. Drake, SCE l
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.4 PRELIMINARY NOTIFICATION i
4.h; April 10, 1973 i
f" PRELIMINARY NOTIFICATION OF EIENT OR UNUSUAL OCCURRENCE--PNO-79-77(NRR)
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This preliminarv notification constitutes EARLY notice of event of POSSIBLE safaty or public interest significance.
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presented is as initially received without verifica*.len or evaluation and is basically all that is known.by NRC_ staf f on thi s date_.,
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Facility:.A11. Light Water Pod r Reactor Facilities
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Subject:
REVIEW 0F OPERATIONAL AND SYSTEM PROBLEHS IDENTIFIED DURING 3=1j.
THE THREE MILE ISLAND INCIDENT 4
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As previously discussed in IE'Bulletins 79-05 and 79-05A, the Three Mile
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Island Nuclear Power Plant, Unit 2, experienced significant core damage
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which resulted from a series of events initiated by a loss of feedwater transient and compounded by operational errors.
Press'.:rizer level indica-
.-T tion appears to have been a contributing factor by leading to erroneous inferences of level in the reactor coolant system.
It has been determined that in some Westinghouse designed facilities, coincident low pressurizer l'
pressure (Pp) and low pressurizer level (Lp) signals are required to
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actuate safety injection, and further that preliminary analyses of a small break in the pressurizer indicate that Lp may remain high while Pp continues
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to decrease.
In such a case, safety injection would not automatically i-occur, and reliance by the operator on Lp could possibly lead to erroneous
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actions.
On April 7,1979, Vestinghouse advised owners with plants having coincident logic for safety injection signals that operators should manually C
intiate safety injection if Pp drops below the safety injection initiation setpoint.
Available related information is, attached.
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The extent to which
>is and other important aspects of the Three Mile
.7; Island accident are generically applicable to Westinghouse and Combustion F
Engineering designed reactors is still being reviewed, but it has been 7 '" "
concluded that further actions should be considered on a priority basis
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for all light watei power reactor facilities.
Meetings are scheduled to Y'
be held on April 11, 1979 with vendors to discuss the extent to which all i
aspects of the Three Mile Island accident have generic applicability to I
Westinghouse and Combustion Engineering designed reactors so that further
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appropriate short-term corrective. tions can be developed and implemented.
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Continued April 10, 1979 7
page 2 PHO-79-77(HRR) 5.%,,
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Contact:
DFRoss, liRR x27373 DGEisenhut, h2R x27221 Ni G:
Distribution:
Transmitted H St/./ v' -
t iM Chairman Hendrie Comissioner Bradford
- 5. J. Chilk, SECY hv Comissioner Kennedy Commissioner Ahearr.e C. C. Kameror, CA 4
Comissioner Gilins's (For Distribution)
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.$.I Transmitted:
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'f. Bld9 7 yo ed J. G. Davis, IE 3-:
L. V. Gossick, EDO
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. H. R. Dentoli, NRR Region _T EWi H. L. Ornstein, E00
'R. C. DaYoung, ilRR Regton II' 5?
J. J. Fouchard, PA
.R. J. Mattson, fiRR Region III di
'R. S. Boyd, NRR P.egion V W f :t-
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H. K. Shapar, ELD ISS Bldg g $$
(PAIL) iW. J. Dircks, tiMSS J. J. Cummings, DIA h-t TMI (IE) Site Yl/2nf/g ( !S. Levine, RES R. Minogue, SD A
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