ML20064B912
| ML20064B912 | |
| Person / Time | |
|---|---|
| Site: | FitzPatrick  |
| Issue date: | 10/06/1978 |
| From: | Early P NEW YORK, STATE OF |
| To: | Ippolito T Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7810120055 | |
| Download: ML20064B912 (3) | |
Text
t 4
~.
POWER AUTHORITY OF THE STATE OF NEW YORK 10 CoLUMaus CIRCLE NEW YORK, N. Y.10o19 (212) 397 6200
~
ER LbANAGER r:EDERICK R CLARK
' *,\\
CEORGE L. INGALLS
' #. L.
A 3RAL si.s. TANT. N Rai.
R-N, ma cNAmNAN WILBUR L. GRONSERO
- a'sER.ENG NEER Ne NAN COSiRT L MILLONZI October 6,1978 JOna w;,=gS,rog WILLIAM F.LUDDY
- = a ~======
JNRC-78-49 THO M AS RANN.JR.
Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, D. C.
20555 Attention:
Mr. Thomas A. Ippolito Operating Reactors Branch No. 3 Division of Operating Reactors
Subject:
James A. FitzPatrick Nuv'.'ar Power Plant Reactor Protection System Power Supplies Docket No. 50-333
Dear Sir:
The Power Authority has reviewed the Nuclear Regulatory Commission's August 7,1978 letter concerning the design of the motor-generator sets which supply power to the reactor protection system for the James A. FitzPatrick Nuclear Power Plant. As requested by the Commission, the Authority has evaluated the reactor protection system power supplies in light of the informa-tion set forth in Attachment 2 (" Extract from Safety Evaluation
-Report Related to Operation of E. I. Hatch Nuclear Plant, Unit 2",
l Docket No. 50-366, June 1978) of the aforementioned letter. Also, promptly upon receipt of the Commission's August 7,1978 letter, I
the Authority instituted the interim surveillance program for the reactor protection system power supplies as set forth in Attachment 1 of the letter. of the August 7,1978 letter indicated Commission concerns regarding the adequacy of protection afforded the reactor pro-tection system agamst possible sustained over-voltage conditions from the non-Class 1E power supplies. Specifically, in their review of the
~
l Hatch Unit 2 operating license application, the Commission postulated a single undetected failure of an output voltage sensor for either motor-LPDR generator set caused by a seismic event, followed by a failure in the 5
gggl)g 1 A Y Y SS'
~m
, ~
,p
. motor-generator set voltage regulating circuitry and resulting in abnormal generator output voltage outside of the range of the con-necte'd Class 1E loads. Such failures would then result in the reactor protection system receiving a supply for some period of time which is outside of its limits, thereby sustaining damage to its components with an attendant potentia 11oss of capability to scram the reactor.
Normally, the motor-generator set output voltage is main-tained virtually constant by means of a voltage regulator. Additionally, protective devices isolate the output from the reactor protection sys-tem if the voltage or frequency varies beyond specified tolerances.
This power supply system at FitzPatrick is basically identical to that proposed for Hatch Unit 2, and the components in question are not seismically qualified. Specifically, the over-voltage relays used to r
trip the reactor protection system power supply have never been
" officially" seismically qualified. However, Boiling Water Reactors have experienced a long history of trouble-free performance of this equipment in operation in the field (134 reactor years of operation without a reported failure) including operating units (Fukushima and Tokai) recently surviving real seismic events of magnitude (7.5 on the Richter scale) higher than that for which they would be required to be
" officially" qualified for the FitzPatrick site.
The Power Authority believes that, while the unique combina-tion and sequence of events postulated by the Commission is technically feasible and within the realms of imagination, its probability of occur-rence is of such extremely low magnitude as to be negligible.
The Power Authority has put the required interim surveillance i
requirements for the reactor protection system (set forth in Attach-mer'.1 of the August 7,1978 letter) into effect, and such requirements wn1 be continued until otherwise directed or authorized by the Commission. An inspection conducted by the Nuclear Regulatory Comrnission's Office of Inspection and Enforcement on September 20 -
22,1978 included a review of the interim surveillance requirements, and indicated that such measures provided satisfactory assurance of detection of failures' due to sustained over-voltage or under-voltage conditions. However, based on the reasons presented in this letter,
the Authority feels that a continuation of the interim surveillance is not warranted. Similarly, the Authority believes that no modifica-tions to the reactor protection system power supplies are required.
Very truly yours,
/
~
G4 Pa J. Early l
As istant C ef Engineer-Projects Subscribed and sworn to before l
me this /c day of October,1978
[.d
/
Notary Publid L'
RUTH G. ZAPF '
Notary Public. State of New Ye'rE No. 30-4G53428
'((. -. chi f3.a$re I 91T
'I l
(
,.n
...--n--,
- - -,-