ML20080R494

Documents Results of 840109 Telcon Between Westinghouse,Util & F Burroughs & T Dunning of NRC Instrumentation & Control Sys Branch Re Lack of Credit for Reactor Trip on Turbine Trip Logic in FSAR Chapter 15

ML20080R494
Person / Time
Site:	Beaver Valley
Issue date:	02/21/1984
From:	Woolever E DUQUESNE LIGHT CO.
To:	Knighton G Office of Nuclear Reactor Regulation
References
2NRC-4-013, 2NRC-4-13, NUDOCS 8402280306
Download: ML20080R494 (2)

Text

'

m

/

$IVs 2NRC-4-013 (412)787 - 5141 Telecopy 6 Nuclear Construction DMalon February 21, 1984 Robinson Plaza, Building 2, Suite 210 Pittsburgh, PA 15205 United States Nuclear Regulatory Commission Washington, DC 20555 ATTENTION: Mr . George W. Knighton, Chie f Licensing Branch 3 Of fice of Nuclear Reactor Regulation

SUBJECT:

Beaver Valley Power Station - Unit 2 Docket No. 50-412 Reactor Trip,on Turbine Trip Gentlemen:

The purpose of this letter is to do cument the res ult s of the January 9, 1984, telecon between Westinghouse, Duquesne Light Company, assi Mr. Fred Burroughs and Mr. Tom Dun ning of the NRC Ins trume nt at io n and Control Systems Branch. The telecon was held to reso lve NRC que s t ions concerning the Reactor Trip on Turbine Trip Logic. A turbine trip causes a reactor trip above P-9. This trip is anticipatory and was included as part of good engineering pract ice and prudent de s ign fo r pr ot ect ion of the turbine equipment . No credit is taken for this trip in any Chapter 15 accident analys is . A description of the trip and the associated logic can be found in Section 7.2.1.1.2 of the Beaver Valley Unit 2 FSAR.

The reacto r trip on turbine trip is actuated by two-out-of-three logic from low emergency trip fluid or by four-out-of-four cloaed s ign als from the turbine main stop valves . Mr. Dun ning que s t ioned the basis fo r the four-out-of-four logic . Part icularly his concern was with the applica-tion of IEEE 279-1971 to this circuit (i.e., a single failure defeats the logic). The justification provided by Westinghouse is this trip is antici-patory and is not assumed in the accident anal ys is . Furthermore, the two-out-of-three logic fo r low emergency trip fluid provides a diverse backup to the s top valve pos it ion logic. When this logic was de s ign ed , the diverse logic and commercial concerns with the turbine stop valves were the bases for the fo ur-out-o f-four logic de s ign . Fur t he rmo re , it was point ed out that even though the logic is ind ica t ed to be redundant on the f un c-tional diagrams, that does not imply that the logic meets all requirement s of IEEE 279-1971.

Sect ion 7.2 also s t ates that the fun ct ion al pe rfo rmance of the protection system would not be degraded by credible electrical f ault s , such as opens and shorts in the circuits as sociated with reactor trip on turbine trip.

8402280306 840221 1 PDR ADOCK 05000412 PDR Agpl A

' 0

j* United Stctes Nuclear Ragulatory Commission Mr. George W. Knighton, Chief Page 2 Finally, Mr. Dunning was referred to r.: e uts for which the ICSB has previously approved a similar design (Mills tone , Byron /Braidwood) . Mr.

Dunning agreed that the issue would be closed following rece ip t of formal documentation of the above information from Duquesne Light Company.

DUQUESNE LIGHT COMPANY By

• E. 3. Woolever Vice President KAT/wjs cc: Mr. G. Walton, NRC Resident Inspector Ms. L. Lazo, Project Manager