ML20198H433

Discusses Open Item on AP600 Design of Core Makeup Tank Instrumentation & Controls.In Staff Issued Open Item 420.127F Documenting Concern.Westinghouse Responded in & Open Item 420.127F Considered Resolved

ML20198H433
Person / Time
Site:	05200003
Issue date:	12/30/1997
From:	Huffman W NRC (Affiliation Not Assigned)
To:	Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
References
NUDOCS 9801130290
Download: ML20198H433 (4)

Text

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. p* t UNITEu STATES

,j NUCLEAR REGULATORY CGMMISSION W AsHINGTON, D.C. 3066Ho01 December 30, 1997

% * . . + ,/y Mr. Nicholas J. Liparuto, Manager Nuclear Safety and Regulatory Analysis  !

Nuclear and Advanced Technology Divis5n 1 Westinghouse Electric Corporation P.O. Box 355  :

Pittsburgh, PA 15230 '

SUBJECT:

OPEN ITEM ON THE AP600 DESIGN OF THE CORE MAKEUP TANK (CMT)

INSTRUMENTATION AND CONTROLa

Dear Mr. Uparulo:

The U.S. Nuclear Regulatory Commission staff had concerns about the possibility of a common mode undetectable failure of the CMT levelinstrumentation due to a design in which the instruments at each CMT actuation setpoint level share the same set of level taps, in a letter dated Decemeber 2,1997, the staff issued an open item (420.127F)(bcumenting this concem.

Westinghouse letter NSD-NRC 97 54r4 dated December 11,1997, responded to the NRC open item by performing a fa"'are mode and effects analysis (FMEA) which provided additional justification as to why the use of shared leve! taps is acceptable for the CMT level  ;

, instrumentation design.

In the FMEA discussion, Westinghouse states that the failures of insturmentation valves V1, V2, V5 or V7 as well as the pluggage or breakage of the level tap lines could inhibit the CMT automatic protective functions. However, the FMEA justifies the design by explaining that administrative controls, proper location of the sensing line, and the use CMT top temperature instruments to detect the leakage discounts the possibility of a credible common mode failure mechanism. The staff has evaluated the CMT levelinstrumentation design FMEA and concluded that there is no credible common mode failure mechanism which will disable CMT injecticn capaL,lity within the scope of a design basis accident. Open item 420.127F is considered resolved, however, the staff has followup ? pen items related to documentation of the information Westinghouse submitted in its open item response. The open items are designated as final safety evaluation report open items and are provided in the enclosure to this letter.

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. i Mr. Nicholas J. Liparulo - 2- December 30, 1997 <

If you have any questions regarding this matter, you may contact me at (301) 4151141.  ;

Sincerely,

, original signed by: ,.  !

~

William C. Huffman, Project Manager Standardization Project Directorate Division of Reactor Program Management l Office of Nuclear Reactor Regulation .' >

I  :

Docket No. 52 003 l

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Enclosure:

As stated

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j DISTRIBUTION

- Docket File PDST R/F JRoe PUBLIC DMatthews TQuay TKenyon WHuffman JSebrosky JNWilson DScaletti JMoore,0-15 B18 WDean,0 5 E6 ACRS (11) HLi,0 8 H3 MChiramal,0 8 H3 JWermlel. 0-8 H3 Alevin,0-8 E23 RCaruso,0 8 E23 TCollins 0-8 E23 DOCUMENT NAME: A:CMT Ol.SER , .s n ,*. . , e *, . hae.i. m m. w,, ca - cory w,mous an. chm.pneio.u,. *t < copy ..* n. chm nti.netosur. 'N' = No copy 0FFICE PM:PDST:DRPM l BC:HKQ:,DSCH c- BC: $ M D W E O:PDST:DRPM l NAME WOiuffANhW JWerm F , TCot N t" TR0uay'TM2 DATE 12SD/97 12/30/37 1

• Y2/7#97 1240/97 OFFICIAL RECORD COPY d

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Mr. Nicholas J. Liparuto Docket No. 52 003

. Westinghouse Electric Corporation AP600 i

l cc: Mr. B. A. McIntyre Mr. Russ Bell Advanced Plant Safety & Licensing Senior Project Manager, Programs Westinghouse Electric Corporation Nuclear Energy institute i Energy Systems Business Unit 1776 l Street, NW l P.O. Box 355 Seite 300 l Pittsburgh, PA 15230 Washington, DC 20006 3706 l Ms. Cindy L. Haag Ms. Lynn Connor Advanced Plant Safety & Licensing Doc Search Associates Westinghouse Electric Corporation Post Office Box 34 Energy Systems Business Unit Cabin John, MD 20818 Box 355 Pittsburgh, PA 15230 Dr. Craig D. Sawyer, Manager Advanced Reactor Programs Mr. Sterling Franks GE Nuclear Energy U.S. Department of Energy 175 Curtner Avenue, MC 754 NE 50 San Jose, CA 95125 19901 Germantown Road Germantown, MD 20874 Mr. Robert H. Buchholz GE Nuclear Energy Mr. Frank A. Ross 175 Curtner Avenue, MC 701 U.S. Department of Energy, NE-42 San Jose, CA 95125 Office of LWR Safety and Technology 19901 Germantown Road Barton Z. Cowan, Esq.

Germantown, MD 20874 Eckert Seamans Cherin & Mellott 600 Grant Street 42nd Floor Mr. Charles Thompson, Nuclear Engineer Pittsburgh, PA 15219 AP600 Certification NE 50 Mr. Ed Rodwell, Manager 19901 Germantown Road PWR Design Certification Germantown, MD 20874 Electric Power Research Institute 3412 Hillview Avenue Mr. Robert Maiers, P.E. Palo Alto, CA 94303 Pennsylvania Department of Environmental Protection Bureau of Radiation Protection Rachel Curson State Office Building P.O. Box B469 Harrit3urg, PA 17105-8469

OPEN ITEM ON THE AP600 DESIGN OF THE CORE MAKEUP TANK (CMT) .

, INSTRUMENTATION AND CONTROLS i

420.128F SSAR section 7.3.2.1 references WCAP 13594 and WCAP 13662 (SSAR Section 7.2.4),

"FMEA of Advanced Passive Plant Protection System" as the Failure Mode and Effects Analyses docketed information supporting the evaluation of the protection and safety monitoring system. The staff took credit for the FMEA analysis contained in these WCAPs in its safety evaluation. By letter NSD NRC 97 5484, dated 12/11/97, Westinghouse responsed to FSER open item 430.127F (OITS#6242) on the CMT level instrumentation in which a detailed FMEA is provided and used to justify the CMT level instrumentation design arrar9ements. The staff concludes that the FMEA for the CMT level instrumentation should be included in the FMEA WCAPs 13594 and 13662 as a condition of the staff's acceptance of the CMT levelinstrumen-tation design.

420.129F Westinghouse has included a note with the CMT levelinstrumentation drawing which states that the location of the upper and lower CMT lovel piping headers should be about 1 inch lower than their connection to the CMT, This is an import design feature which should be included for verification in ITAAC.

Enclosure

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