ML20139A281
| ML20139A281 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 04/24/1997 |
| From: | Huffman W NRC (Affiliation Not Assigned) |
| To: | Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| References | |
| NUDOCS 9704250184 | |
| Download: ML20139A281 (3) | |
Text
.
April _24, 1997 i-Mr. Nicholas J. Liparulo, Manager Nuclear Safety and Regulatory Analysis Nuclear and Advanced Technology Division i'
Westinghouse Electric Corporation
.)
j-P.O. Box 355 a
Pittsburgh, PA -15230
SUBJECT:
REQUESTS FOR ADDITIONAL INFORMATION (RAIs) RELATED TO THE APPLICA-TION OF WCOBRA/ TRAC FOR LONG TERM COOLING (LTC) ANALYSES OF THE-AP600
~
Dear Mr. Liparulo:
In support of the AP600 design certification review, the Nuclear Regulatory Commission (NRC) staff is evaluating the use of the WCOBRA/ TRAC large break loss-of-coolant-accident analysis computer code for assessing the LTC perfor-mance of the AP600.
Westinghouse letter NSD-NRC-96-4877, dated November 6, 1996, submitted the WCOBRA/ TRAC OSU Long-Term Cooling Final Validation Report, WCAP-14776.
The staff submitted RAls on this report on March 4, 1997, and March 20, 1997.
On March 28, 1997, Westinghouse met with the Advisory i
Committee for Reactor Safeguards (ACRS) thermal-hydraulic subcommittee to present the status of the WCOBRA/ TRAC LTC methodology.
Based on discussions i
during the ACRS meeting, the staff has several additional questions on the application of WCOBRA/ TRAC LTC analysis to the AP600. The questions.are i
provided as RAIs in an enclosure to this letter.
If'you have any questions regarding this matter, you can. contact me at
)
(301) 415-1141.
.l Sincerely, '
l original signed by:
'WilliamC.Huffman,ProjectManager l;
Standardization Project Directorate i
Division of Reactor Program Management
-Office of Nuclear Reactor Regulation Docket No.52-003 i
Enclosure:
' As stated cc w/ enclosure:
- gg%f,h81S See next page
}
DISTRIBUTION:
Docket File PDST R/F TMartin I
-y$)
PUBLIC MSlosson
.TRQuay TKenyon BHuffman-
.JSebrosky DJackson JMoore, 0-15 B18 WDean,:0-17 G21
-ACRS (11)
Llois, 0-8 E23 Alevin, 0-8 E23
-JLyons, 0-8 E23 GHolahan, 0-8 E2 DOCUMENT NAME: A:WCT-LTC3.RAI
- See previous concurrence To,eielve a copy of thle docunwnt,indcato in the boa: 'C' = Copy without ettechment/ enclosure
'E' = Copy with attachmerrt/ enclosure "N" = No copy 0FFICE PM:PDST:DRPM SRXB:DSSA D:PDST:DRPM l l
NAME WCHuffman:bj@ Alevin*-
TRQuay T 4 DATE 04/S/97 04/ /97 04/vt/97 0FFICIAL RECORD COPY 9704250184 970424 PDR ADOCK 05200003 A
b 1
1 i
Mr. Nicholas J. Liparulo Docket No.52-003 Westinghouse Electric Corporation AP600
~
cc: Mr. B. A. McIntyre Mr. Ronald Simard, Directo;-
Advanced Plant Safety & Licensing Advanced Reactor Programs z.
Westinghouse Electric Corporation Nuclear Energy Institute
-Energy Systems Business Unit 1776 Eye Street, N.W.
P.O. Box 355 Suite 300 j
Pittsburgh, PA 15230 Washington, DC 20006-3706 i
i Ms. Cindy L. Haag Ms. Lynn Connor i
Advanced Plant Safety & Licensing Doc-Search Associates Westinghouse Electric Corporation Post Office Box 34 j
Energy Systems Business Unit Cabin John, MD 20818 Box 355 Pittsburgh, PA 15230 Mr. James E. Quinn, Projects Manager LMR and SBWR Programs Mr. M. D. Beaumont GE Nuclear Energy Nuclear and Advanced Technology Division 175 Curtner Avenue, M/C 165 Westinghouse Electric Corporation San Jose, CA 95125 One Montrose Metro 11921 Rockville Pike Mr. Robert H. Buchholz j
Suite 350 GE Nuclear Energy Rockville, MD 20852 175 Curtner Avenue, MC-781 San Jose, CA 95125 i
Mr. Sterling Franks j
U.S. Department of Energy Barton Z. Cowan, Esq.
j NE-50 Eckert Seamans Cherin & Mellott i
19901 Germantown Road 600 Grant Street 42nd Floor Germantown, MD 20874 Pittsburgh, PA 15219 i
Mr. S. M. Modro Mr. Ed Rodwell, Manager l
Nuclear Systems Analysis Technologies PWR Design Certification 1
i Lockheed Idaho Technologies Company Electric Power Research Institute i
Post Office Box 1625 3412 Hillview Avenue Idaho Falls, ID 83415 Palo Alto, CA 94303 1
Mr. Frank A. Ross Mr. Charles Thompson, Nuclear Engineer U.S. Department of Energy, NE-42 AP600 Certification Office of LWR Safety and Technology NE-50 l
19901 Germantown Road 19901 Germantown Road j
Germantown, MD 20874 Germantown, MD 20874 l
)
a I
i 1
AP600 REQUEST FOR ADDITIONAL INFORMATION i
440.645 In the context of the application of the WC/T to the AP600, containment pressure is a boundary condition which impacts the windows solution of primary interest to the staff - reactor vessel water level. Westinghouse is requested to provide the following information concerning the use of-the WC/T windows approach for AP600 calculations.
(a)
How is the containment pressure coupled to the injection tempera-ture?
(b)
How are the Sump and IRWST level boundary (or initial) conditions determined for LTC?
I (c)
How is reactor vessel water level affected by the variations in containment pressure during and between windows?
(d)
How is the OSU measured vessel level related to the AP600 calcu-lated level at containment pressures higher than atmospheric?
(e)
How is the time required to drain the IRWST determined? Since time determines the decay heat, how was this calculation quali-fied?
440.646 Containment pressure has not been a parameter in the OSU experiments.
In addition, coupled WC/T and WG0THIC solutions have not been submitted and containment pressure change scenarios have not been clearly investigated i
or discussed. Westinghouse needs to provide sufficient justification that the long term cooling solution is essentially stable considering fluctuations of containment pressure. Westinghouse should demonstrate that during long term cooling, upon initiation of core boiling, if containment pressure were to drop to atmospheric (or close to it), that the increased boiling would not create a high enough pressure in the vessel to prevent (temporarily) DVI flow or result in core uncovery and accelerate boiling, which could lead to a diverging core cooling solu-tion. Westinghouse should also address what physical parameters would prevent this scenario and how is WC/T able to provide a reliable response to such a transient?
4 i
e Enclosure T
A 4