ML20151P029

Safety Evaluation Supporting Generic Ltr 83-28,Position 4.5.1 Re on-line Testing of Reactor Trip Sys

ML20151P029
Person / Time
Site:	Grand Gulf
Issue date:	08/05/1988
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20151P026	List: ML20151P022 ML20151P029
References
GL-83-28, NUDOCS 8808090163
Download: ML20151P029 (2)

Text

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l ENCLOSURE SAFETY EVALVATI0h BY THE OFFICE OF NUCLEAR REACTOR REGULATION GENERIC LETTER 83-28, POSITION 4.5.1 GRAND GULF NUCLEAR STATION, UNITS 1 AND 2

1.0 INTRODUCTION

Generic Letter (GL) 83-28 was issued by the staff on July 8,1983.

It described intermediate-term actions i.c be taken by the licen3ees and applicants to address the generic issues raisad by the two anticipated I transients without scram ( ATWS) events that o.. curred at Unit 1 of Salem <

Nuclear Power Plant. These actions were deve;oped by the staff, based on l

information contained in NUREG-1000, "Generic Implications of ATWS Events ,

at the Salem Nuclear Power Plant." Actions to be performed included I development of programs to provide for post-trip review, classification of i equipment, vendor interface, post-maintenance testing, and reactor trip system (RTS) reliability improvements. T.51s report is the Safety Evaluation of the licensee's responses to P uition 4.5.1 of GL 83-28.

2.0 EVALUATION By letters dated November 4, 1983, September 11, 1984, and June 12, 1985, the licensee provided information regarding their compliance to Position 4.5.1 of GL 83-28. We evaluated the licensee's responses against the NRC positions described in GL 83-28 for completeness and adequacy. We found the licensee's response to Item 4.5.1 to be incomplete, thus requiring additional information to determine acceptability. The deficiency wa$

described in our request for additional information cated July 31,198/.

The licensee's supplemental response to our request for additional information was submitted by the licensee on October 16, 1987.

Position 4.5.1 cf GL 83-28 requires on-line functional testing of the reactor trip system, including independent testing of the diverse trip features. The diverse trip features to be tested on General Electric

' ,..(GE) plytts include the scram pilot valve and backup-scram valves (including all initiating circuitry).

The licensee's response dated September 11, 1984, addressed the GL 83-28 requirement to perform functional testing of the reactor protection system scram pilot valve and initiating circuits, plus the feasibility of on-line testing of the backup scram valves. The licensee stated that "functional testing of the scram pilot valves and initiating circuitry is provided at GGNS." The response further described the five systems whicn contribute to the reactor trip iJnction. The primary systems are the 8808090163 DR 880805 ADOCK 05000416 PDC

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reactor protection system (RPS) and the control roo drive system (CRDS).

Sensors from the three other systems (neutron monitoring, nuclear boiler l instrumentation, and process radiation monitoring) provide information I abcut conditions of plant operation. The licensee stated that on-line i functional testing is provided and that each sensor channel functional i test includes full actuation of the associated !ogic, the two output sc. ram  !

contactors in ecch channel, and the individual CR0 scram air pilot valve l solenoids for the associated logic division.

The li,ensee stated that on-line testing of the backup scram valves is not fratible, due to the design of the plant and, if on-lint testing were I perfr.raied, it would result in scranuling the p' ant. The licensee indicated tha* the system at GGNS incluttes two scram va ves and one scram pilot va7ve for each of the 193 control rods. The system contains two DC  :

pc'< err.d. solenoid operated backup scram valves that are energized to I o;erste, as ccmpared with the scram system which is AC-powered and ne-energized to function.

In its letter to the licensee dated July 31, 1987, the staff concluded that modificiations to the system to allow on-line testing of tb backup scram valves would not be required. The staff further concluded tnat testing of the backup scram valves, including initiating circuitry, during each refueling outage is an acceptable alternative to on-line testir.g and requested a descriptiori of such tests. The licensee's response of October 16, 1987, provided test procedures and a commitment to perform these tests during each refueling outage. The staff is reviewing these test procedures and will provide its evaluation of the procedures together with its evaluation of GL 83-28, Positions 4.5.2 and 4.5.3,

3.0 CONCLUSION

The licensee performs on-line testing of the scram pilot valves and initiating circuitry for reactor trip systems as required by GL 83-28, Position 4.5.1. The licensee cannot perform on-line testing of the backup scram valves, since such testing would scram the reactor.

However, the licensee has committed to perform off-line tests cach refueling outage for the backup scram valves. Such alternative testing is allowed by GL 83-26, Position 4.5.2. The staff concludes that the licensee's responses a GL 83-28, Position 4.5.1, meet the requirernents of GL 83-28 and are acceptable. subject to the staff's r; view of the off-line testing of backu? scram valves.