ML20198H352
| ML20198H352 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 12/22/1997 |
| From: | Huffman W NRC (Affiliation Not Assigned) |
| To: | Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| References | |
| NUDOCS 9801130262 | |
| Download: ML20198H352 (4) | |
Text
_ _ _ _ _ _ _ _ _ _ _ - - - _ _ _
k i
Deccmber 22, 1997 Mr. Nicholas J. Liparulo, Manager Nuclear Safety and Regulatory Analysis Nuclear and Advanced Technology Division Westinghouse Electric Corporation P.O. Box 555 Pittsburgh, PA 15230
SUBJECT:
OPEN ITEMS ASSOCIATED WITH THE AP600 SAFETY EVALUATION REPORT (SER) ON THE REGULATORY TREATMENT OF NON-SAFETY RELATED SYSTEMS
Dear Mr. Liparuto:
The Reactor Systems Branch of the U.S. Nuclear Regulatory Commission has provided a draft SER input to the Standardization Project Directorate on the AP600 Regulatory Treatment of Non-Safety Related Systems (RTNSS). The input has open items which have been extracted and designated as final safety evaluatior, report open items in the enclosure to this letter.
if you have any questions regarding this matter, you may contact me at (301) 415-1141.
Sincerely, Original signed by:
William C. HtJfman, Project Managar Standardization Project Directorate Division of Reactor Program P*cnagement Office of Nuclear Reactor Reg. ation Docket No.52-003
' inclosure: As stated j(
Y lh)f nr cc w/ encl: See next page DISTRIBUTION-1 Docket File PDST R/F TQuay PUBLIC TKenyon WHuffman JSebrosky DScaletti JNWilson ACRS (11)
WDean,0-5 E23 JMoore,0-15 B18 Alevin, O-8 E23 RCaruso,0-8 E23 TCollir,s,0-8 E23 SNewberry,0-8 E2 GHolahan,0-8 E2 JFlack, C-10 E4 o'
ggI NSaltos,0-10 E4 AEl-Bassioni O-10 E4 DOCUMENT NAME: A:RTNSS.OI To receive a copy of this document, Indicate in the box: "C" = Copy without attachment / enclosure "E" = Ccpy with attachment / enclosure "N" = No copy OFFICE PM:PDST:DRPM BC:SRXB:DSSA SC:SPSB:DSSA l D:PDST:DRPM
- NAME, WCHuffman:h TCollins~/g>
AEl-Bassioni M//
TRQuay Tkg DATE 120D/97 12/>2/97 12/tL/97 12/n /97 OFFICIAL RECORD COPY 9801130:?62 971222
{DR ADGCK 05200003 PDR i
i h
d l
Mr. Nicholas J. Liparuto Docket No.52-003 Westinghouse Electric Corporation AP600 cc:
Mr. B. A. McIntyre Mr. Russ Bell Advanced Plant Safety & Licensing Senior Project Manager, Programs Westinghouse Electric Corporation Nuclear Energy Institute Energy Systems Business Unit 17761 Street, 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 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 u
Germantown, MD 20874 Mr. Robert H. Buchholz 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 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 Pretection Rachel Carson State Offico Building P.O. Box 8469 Harrisburg, PA 17105-0469 t
. i, j
OPEN ITEMS ASSOCIATED WITH REACTOR SYSTEMS BRANCH EVALUATION OF THE AP600 REGULATORY TREATMENT OF NON-SAFETY RELATED SYSTEMS 440.803F Westinghouse submittal NSD-NRC-97-5485, dated December 12,1997 addresses issues raised by the staff (in its letter dated October 2,1997) on the AP600 administrative controls used to ensure the availability of RTNSS important systems. The staff has not yet completed its leview of the Westinghouse RTNSS responses. The acceptability of the responses is an open item.
440.804F Section A of SECY-94-084," Policy and TechnicalIssues Associated with the Regulatory Treatment of Non-Safety Systems (RTNSS)in Passive Plant Designs," March 28,1994, discusses the process used (a) to develop insights regarding the importance of non-safety-related systems to the overall safety of the AP600 design, and (b) to determine what, if any, additional regulatory contro s should be implemented for those non-safety-related systems detennined to be important to safety. Chaper 22 of the FSER discusses the RTNSS process in detail.
l Westinghouse's original evaluation of RTNSS implementation is discussed in WCAP-13856, "AP600 Implementation of the Regulatory Treatment of Nonsafety-Related Systems Process." In addition, the focused PRA sensitivity study that forms a major part of the RTNSS process is contained in Chapter 52 of the AP600 PRA. The original evaluation in WCAP-13856 identified only two conditions requiring regulatory controls on non-Safety-related systems: the reactor trip function of the Diverse Actuation System (DAS) for m;tigation of anticipated transients without scram (ATWS), and the normal residual heat removal system (RNS) and supporting fluid and ac electrical and systems for operations during midloop conditions. However, after extensive discussions with the staff, Westinghouse has agreed to expand the number of SSCs covered by RTNSS and to expand the MODES during which RTNSS controls apply, as discussed in the attachment to Westinghouse letter NSD-NRC-97 5485, dated December 12,1997. RTNSS oversight is accomplished through administrative controls on the identified SSCs, which specify operability requirements, required actions and the time to accomplish those actions ;f the operability requirements are not met, surveillance requirements, end the bases for the controls.
However, there are no limiting conditions for operation associated with these RTNSS controls.
The staff has reviewed ihe administrativs controls related to shutdown operations (MODES 5 and 6), and has identified a concem related to the allowed completion time for required actions during periods of reduced inventory. The proposed administrative control for RNS during MODES 5 and 6 specify that bota RNS pumps should be available prior to entry inte,40DE 5 with the pressure boundary open or MODE 6 with upper intemals in place and the cavity levelless than full. ff one RNS pump subsequently fails, the operator is permitted up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to remove the plant from the MODE in which these controls are applicable. The staff has concluded that this time is excessive when the plant is operating in a reduced-inventory condition. The short refueling schedules proposed for the AP600 mean the plant could be in reduced-inventory conditions for a relatively short time. Thus, it could be possible to enter reduced-inventory operations, then have Enclosure
, 4,
. l the RNS or one of its supporting SSCs become Inoperable, but with the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> action comple-tion time, necessary work could be completed and the plant could exit the MODE within the time specified for operator action. (The same action times are specified for RNS support systems, such as component cooling water, service water, and on-site ac power.) Thus, for reduced-inventory operaHons in the applicable MODES, the 72-hour completion time effectively serves no safety purpose. The staff thus concludes ' hat the administrative controls on RNS and supporting SSCs for reduced-inventory operations during MODES S and 6 are riot conservative and are not consistent with the safe shutdown objective and that action completion times when operability requirements are not met should be more restrictive and consistent with the length of time the plant is expected to be in reduced-inventory operations in the applicable MODES. Resolution of this issue is an Open item.
720.464F Availability control of the reactor trip function of DAS provides an officient means for minimizing the impact of uncertainties in reactor trip components, such as circuit breakers, on PRA results used in the criteria for selecting non-safety related SSCs for regulatory oversight according to the RTNSS process. Such cvailability controls should include the two motor-generator set circuit breakers because the rertor trip function of DAS requires the availability (to open) of both these circuit breakers. Westingiouse should include these circuit breakers as part of the DAS investment protection short term availability controls and propose an appropriate corresponding surveillance.
-