ML20070G601
| ML20070G601 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 03/07/1991 |
| From: | Cottle W ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GNRO-91-00032, GNRO-91-32, NUDOCS 9103120225 | |
| Download: ML20070G601 (2) | |
Text
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U.S. Nuclear Regulatory Commission Mail Station PI-137 Washington, D.C.
20555 Attention:
Document Control Desk
SUBJECT:
Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-29 Implementatit.,a of ARI Diversity Requirements in 10CFR50.62 GNRO-91/00032 Gentlemen:
In a letter dated January 8,1991, the NRC requested Entergy Operations, Inc. to confirm-in writing whether Grand Gulf Nuclear Station (GGNS) complies with the Staff's position regarding diversity of trip units
-(TUs) between the alternate rod. insertion (ARI) system and the reactor-protection system (RPS).
The ATWS rule (10CFR50.62) requires an~ARI system which is diverse (from the RPS) from the sensor output to the final actuation device.
Specifically, the Staff's position as provided in the January 8,1991 NRC letter, requires TUs in the ARI system to be diverse from the TUs in the f
RPS.
The Staff's position is based upon the Statement of Considerations-p' diverse" as used in the ATWS rule.ublished with the ATWS rule which defines wha The Statement of considerations states that "aquipment diversity" is the primary objective of the general term " diverse" in the ATWS rule.
The Staff, as pointed out in Enclosure 2 of the January 8,1991 NRC 1etter, has always interpreted equipment diversity to mean unlike or different equipment.
In the minutes of CRGR Meeting No. 189, the NRC Staff indicated that for an ARI system to be acceptable the ARI TUs-should be of different manufacture than those in the RPS.
By letters dated October 14, 1985 (AECM-85/0322), April 3, 1987 (AECM-87/0055) and June 22, 1987 (AECM-87/0109), GGNS provided information regarding the design features (including the ARI system) to mitigate the-c.onsequences of ATWS events.
The NRC Staff documented the results of their review in an SER attached to a letter dated August ?.i 1987 (MAEC-87/0200).
The NRC Staff found the GGNS ARI system design in conformance with Paragraph (c)(3) of 10CFR50.62 and therefore, acceptable.
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1 March 7, 1991 GNRO-91/00032 Page 2 of 3 The NRC Staff, in a telephone call on March 1, 1988, contacted GGNS regarding the TU equipment diversity issue.
Entergy Operations explaiaed that the GGNS ARI system uses Dailey alarm modules (model 745) to cause the trip functions for the sensed variables (reactor water 1cvel and pressure). The RPS uses Rosemount analog TUs (model 510 DU) to cause the RPS trip function for the reactor water level and pressure sensors.
In addition, GGNS stated Bailey alarm modules are not used in the RPS at all. The Staff concluded the telephone call by saying no further action is expected by GGNS for this issue.
In summary, GGNS does conform to the Staff's position on diversity of the TUs between the ARI system and the RPS.
Yours truly, WOW WTC/ PRS /ams cc:
Mr. D. C. !!intz Mr. J. Mathis Mr. R. B. McGehee Mr. N. S. Reynolds Mr.11. L. Thomas Mr. Stewcrt D. Ebneter Regional Administrator U.S. Nuclear Regulatory Commission Region 11 l
101 Marietta St., N.W.,
Suite 2900 Atlanta, Georgia 30323 Mr. L. L. Kintner, Project Manager Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 11D21 Washington, D.C.
20555 I
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