NRC Generic Letter 1978-32

NRC Generic Letter 1978-032: Reactor Protection System Power Supplies (Grand Gulf Nuclear Station, Units 1 & 2)

ML031280391
Person / Time
Site:	Grand Gulf
Issue date:	08/11/1978
From:	Boyd R Office of Nuclear Reactor Regulation
To:
References
GL-78-032
Download: ML031280391 (4)

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11, 1978 D. Vassallo August J. Stolz rcckt N. 50416C. E. Thomas Hylton accket No. 50-416 and 5-417OELD

B. Scott L. Dreher - G-26 Mississippi Power and Light Company ATTN: Mr. N. L. Stampley 7/ Lo 7 E -j Vice President - Production P. 0. Box 1640

Jackson, Mississippi 39205 Gentlemen:

SUPPLIES

SUBJECT: REACTOR PROTECTION SYSTEM POWER

UNITS 1 & 2)

(GRAND GULF NUCLEAR STATION,

A to General Design Criteria (Appendix such Criterion 2 of the Commission's that systems important to safety,

10 CFR Part 50) requires in part be designed to withstand the effectsIE

as the reactor protection system, systems are required to be Class of earthquakes. Reactor protection protection Category I. The normal reactor systems, hence they are seismic water General Electric Company boiling solid system power supplies for most except for those utilizing reactor nuclear steam supply systems, consist of redundant alternating current state reactor protection systems, seismically qualified.

not motor-generator sets which are license of Georgia Power Company's operating During the course of our review No. 2 (Docket No.

Nuclear Plant Unit application for its Edwin I. Hatch of the protection afforded the reactor

50-366), we questioned the adequacy sustained over-voltage, under-voltage, protection system against possible the reactor protection system power or underfrequency conditions from the capability of the reactor pro- supplies. Specifically, we questioned accommodate the effects of earthquakes tection system power supplies to of the reactor protection system to without jeopardizing the capability function.

to perform its intended safety can be of events initiated by an earthquake We determined that a sequence system damage to the reactor protection postulated which could result in loss of capability to scram the components with the attendant potential (1) the occurrence of an earthquake includes plant. This sequence of events the failure the undetected failure of a voltage sensor, (2) (3) the that would cause in an abnormal output voltage, of a motor-generator set resulting voltage, undetected by visual observa- persistence of this abnormal output a time sufficient to damage reactor for t1ons and surveillance testing, in such

(4) failure of these components protection system components, and of-capability to scram the plant.

a onanner that results in the loss

.

- 2 - August 11, 1978 the first scheduled We, therefore, required that prior to startup following systems approved IE

refueling outage, Georgia Power Company install Class system power by us and capable of de-energizing the reactor protection or their output supplies when their output voltages exceed or fall below being powered frequencies fall below limits within which the equipment to operate con- by the power supplies has been designed and qualified the designs of the tinuously and without degradation. With such systems, to the applicable reactor protection system power supplies will conformPart 50.

requirements of Criterion 2 of Appendix A to 10 CFR

that all applicants Consistent with our finding on Hatch Unit 2, we requireGeneral Electric for licenses to construct and operate plants utilizing with non-seismic Company boiling water reactor nuclear steam supply systems as the normal reactor Category I alternating current motor-generator sets Class IE systems approved by us protection system power supplies install power supplies anu capaDle of de-energizing the reactor protection system their output frequencies when their output voltages exceed or fall below or powered by the power fall below limits within which the equipment being continuously and without supplies has been designed and qualified to operate degradation.

We will implement this requirement as follows:

permit stage

(1) For those applicants with applications in the construction your receipt days of of the review process, we request that within 30 commitment your of this letter, you amend your application to reflect loading and (b)

to (a) install such systems prior to initial fuel your Final Safety Analysis provide the details of the system design in Report.

permit stage, we request

(2) For those applicants in the post-construction of this letter, you document by that within 30 days of your receipt to initial install such systems prior letter your commitment to (a) in your the details of the system design fuel loading and (b) provide Final Safety Analysis Report.

license stage

(3) For those applicants with applications in the operating your receipt of of the review process, we request that within 30 days your commitment of this letter, you amend your application to reflect loading and (b)

to (a) install such systems prior to initial fuel of the system advise us of your schedule for providing the details design in your Final Safety Analysis Report.

-3 - August 11, 1978 Because of the relatively large number of plants involved and the similarity of the reactor protection system power supply designs, we anticipate that you, the other affected applicants, and the General Electric Company may wish to combine efforts in this matter. In the interest of standardization and minimizing the impact of our review of these systems, we encourage such a combined effort.

Sincerely,

_~ /_.-\ -) ,.-,-,

Roger S. Bbyd, Director Division of Project Mana'§Wement-'

Office of Nuclear Reactor Regulation

. '4'

Mississippi Power and Light Company cc: Mr. Robert B. McGehee, Attorney Wise, Carter, Child, Steen &

Caraway P. 0. Box 651 Jackson, Mississippi 39205 Troy B. Conner, Jr., Esq.

Conner, Moore & Corber

1747 Pennsylvania Avenue, N. W.

Washington, D. C. 20006 Bechtel Power Corporation ATTN: T. W. Haberman, Project Engineer Grand Gulf Nuclear Station Gaithersburg, Maryland 20760