ML20198N030

Forwards Open Items on Piping Classification of AP600 Chemical & Volume Control Sys.Open Items Designated as FSER Rept Open Items

ML20198N030
Person / Time
Site:	05200003
Issue date:	01/13/1998
From:	Huffman W NRC (Affiliation Not Assigned)
To:	Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
References
NUDOCS 9801200228
Download: ML20198N030 (5)

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NUCLEAR REGULATORY COMMISClON WASHINGTON, D.c. 30646 4001

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Januar/ 13.-1998 Mr. Nicholas J. Liparulo, Managar Nuclear Safety and Regulatory Analysis Nuclear and Advanced Technology Division Westinghouse Electric Corporation P.O. Box 355 Pittsburgh, PA 15230

SUBJECT:

OPEN ITEMS ON THE PlPING CLASSIFICATION OF THE AP600 CHEMICAL AND VOLUME CONTROL SYSTEM (CVS)

Dear Mr. Liparulo:

i in a letter dated August 25,1997, the U.S. liuclear Regulatory C 1mmission staff raised a concorrnvith Westinghouse that the AP600 CVS piping and components were not classified as ASME, Section Ill, even though the system is part of the reactor coolant pressure boundary.

Westinghouse provided justification for its classification cf the CVS in a latter oted Septem-ber 11,1997, however, the staff was not satisfied wth the response and issued an FSER open item (230.140F) in a letter to Westinghouse dated October 16,1997.

Westinghouse letter NSD NRC-97 5452 dated November 21,1997, responded to the NRC FSF.R open item concerning the classification of the CVS piping. Westinghouse agrees that the CVS piping Inside containment is reactor coolant pressure boundary piping based on the cu..ent definition in 10 CFR 50.2. However, Westinghouse has requested an exemption from the definition of the reactor coolant pressure boundary related to the classification of the CVS piping based on the unique design considerations of the AP600 CVS system. In addition, Westinghouse has modified the design of the CVS supply and return path isolation valves so that there are now three safety related ASME Section lli valves in series in each path which are capable of isolating the CVS piping downstream of the valves from the rest of the RCS should a pipe break occur.

The staff has evaluated the November 21,1997, Westinghouse submittal and has additional.

open items related to the classification of the CVS piping. 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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t Mr. Nicholas J. Liparuto January 13, 1998 ff you have any questions regarding this matter, you may contact me at (301) 415-1141.

Sincerely, original signed by:

William C. Huffman, Project Manager Standardization Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No.52-003

Enclosure:

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Mr. Nicholas J. Liparulo Docket No.52-003 Westinghouse Electric Corporation AP600 cc:

Mr. B. /.. McIntyre Mr. Russ Bell Advanced Plant Safety & Licensing Senior Project Manager, Programs Westinghouse Electric Corporation Nuclear Energy Institute Energy Systems Business Unit 1776 i St eet, NW P.O. Box 355 Suite 300 Pittsburgh, PA 15230 Washington, DC 20006 3706 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 Bcx 355 Pittsburgh, PA 15230 Dr. Craig D. Sawyer, Manager Advanced Reactor Programs Mr. Sterling Franks GE Nuc! ear Energy U.S. Department of Energy 1/S Curtner Avenue, MC-754 NE-50 San Jose, CA 95125 19901 Germantown Road Germantown, MD 20874 Mr. Robert H. Buenholz GE Nuclear Energy Mr. Frank A. Ross 175 Curtner Avenue, MC 781 U.S. Department of Energy, NE-42 San Jose, CA 95125 Office of I > ?

'd efy and Technology 19901 Gei 4cwn 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 Carson State Office Building P.O. Box B469 Harrisburg, PA 17105-8469

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OPEN ITEMS ON THE PIPING CLASSIFICATION OF THE AP600 CHEMICAL AND VOLUME k

CONTROL SYSTEM (CVS) 230.145F The design changes made to the CVS as provided in Westinghouse letter NSD-NRC 97 M52 dated November 21,1997, are acceptable to the staff. However, the request for exemption to the definition of reactor coolant pressure boundary is too broad and, therefore, not acceptable.

The CVS p! ping within containment is part of the reactor coolant pressure boundary and will not be considered otherwise. An exemption to 10 CFR 50.55a(c) may not be necessary if Westinghouse justifies its proposed alternative classification of the CVS reactor coolant pressure boundary piping under 10 CFR 50.55a(s)(3). Westinghouse should discuss how its c4ssification of the CVS would provide an acceptable level of quality and safety considering the quality, inspection, and integrity criteria for reactor coolant pressure boundary cited in GDCs 14, 30, and 32. Westinghouse should also discuss the conformance and exceptbns of its classification with regulatory guide 1.2L in addition, Westinghouse should address how the AP600 will be shut down and cooled down in an orderly manner assuming makeup is provided by ths reactor coolant makeup system only, as discussed in 10 CFR 50.55a(c)(2)(ii). The staff notes that the AP600 would not be able to rely on makeup from the CVS for shut down in an orderiv manner since the CVS piping is non safety related and non-seismic and may not be avallw.e due to isolation or breakage. Westinghouse should include thi6 discussion in the SSAR.

230.146F 10 CFR Part 50, Appendix S, Section ill, requires that the integrity of 'he reactor coolant pressure boundary be maintained followir'g a safe shutdown earthquake (SSE). The.taff is concerned that the CVS piping is non-seismic and, consequently, its integrity cannot be assured following an SSE. The staff believes that the CVS piping should be designed to withstand an SSE without failure. Westinghouse should commit that the CVS system within containment will be designed, analyzed, and constructed to meet the seismic requirements of Seismic Category ll structures, systems, and components (SSCs). Tne staff recognizes that otdinarily, for the CVS to be categorized as Seismic Category ll, failure of the CVS SSCs would have to compromise the function of some AP600 safety related SSC. However, to assure the seismic integrity of the CVS, WeMinghouse should commit to designing, analyzing, and constructing the portion of the CVS within containment to the same criteria as that used for Seismic Category ll SSCs, and document this in both the SSAR and the Certified Design Material.

230.147F Westinghouse states in its submittal that the isolation valves between the RCS and the CVS are tested per the Inservice Testing Program. One of the safety functions of these valves is to establish a leaktight barrier assuming that integrity of the downstream piping is lost. Westing-house states that exercise testing of these valves minimizes the probability of unexpected gross failuro and gross leakage of the valvos. The staff considers the currently propos 3d IST program for these valves is insufficient considering that the CVS SSCs are classified as non-ASME Section Ill. The valves should be leak tested at full RCS differential pressure across the valves (simulating the isolation of a downstream piping break). The leak testing and accep-

tance criteria should be as currently required by ASTM Section XI (OM 10) which allows 0.5D gpm or 5 gpm (whichever is less), where D is the nominal valve dialneter expressed in inches.

Enclosure

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230.148F Westinghouse did r ot address how the hydrogen addition piping (LO62 on Figure g.3.61) will be classi'ied. The hydrogen addition piping is non ASME but would be directly connected

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(without any transition valves) to ASME Class C piping under the proposed revised design.

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Please address this omission.

r 230.149F Westinghouse should explain why the motor-operated isolation valves in the CVS supply side (from the RCS cold leg) do not isolate on a safeguards isolation signal in addition to a pressur-Irer low 1 signal. The staff believes that this would provide additional assurance of rapidly isolating a CVS leak.

230.150F Westinghouse should explain how the PRA accounted for a potential increase in LOCA initiation events due to failure of the CVS SGCs based on the system being non-ASME class reactor coolant pressure boundary.

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