ML20140G137
| ML20140G137 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 05/07/1997 |
| From: | Diane Jackson NRC (Affiliation Not Assigned) |
| To: | Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| References | |
| FACA, NUDOCS 9706130373 | |
| Download: ML20140G137 (5) | |
Text
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WASHINGTON, D.C. 20555-0001 May 7,1997 Mr. Nicholas J. Liparulo, Manager Nuclear Safety and Regulatory Activities Nuclear and Advanced Technology Division Westinghouse Electric Corporation P.O. Box 355 Pittsburgh, PA 15230
SUBJECT:
REQUESTS FOR ADDITIONAL INFORMATION (RAls) ON WCAP-14845, " SCALING ANALYSIS FOR AP600 CONTAINMENT PRESSURE DURING DESIGN BASIS ACCI-DENTS"
Dear Mr. Liparulo:
" The Nuclear Regulatory Commission's (NRC) Containment Systems and Severe Accident Branch staff reviewed WCAP-14845, " Scaling Analysis for AP600 Containment Pressure During Design Basis Accidents" and determined that it needs additional information in order to complete its review of the Westing-house AP600 passive containment cooling system and WG0THIC computer code.
Enclosed are questions identified as RAI# 480.1017 to 480.1021.
This is the second of two requests on WCAP-14845, based on commitments from the April 18, 1997, meeting with Westinghouse on the scaling study.
It is expected that WCAP-14845 will be updated to reflect the questions and comments enclosed in this letter.
You have requested that portions of the information submitted in the June 1992, application for design certification be exempt from mandatory public disclosure. While the staff has not completed its review of your request in accordance with the requirements of 10 CFR 2.790, that portion of 1
the submitted information is being withheld from public disclosure pending the staff's final determination.
The staff concludes that these questions and comments do not contain those portions of the information for which exemption is sought. However, the staff will withhold this letter from public disclo-sure for 30 caler.dar days from the date of this letter to allow Westinghouse the cpportunity ta verify the staff's conclusions.
If, after that time, you do not request that all or portions of the information in the enclosures be withheld from public disclosure in accordance with 10 CFR 2.790, this letter will be placed in the NRC Public Document Room.
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9706130373 970507 ADOCK0520g3 PDR BC RLE CENTER COPY
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l Mr. Nicholas J. Liparulo May 7, 1997 If you have any questions regarding this matter, you may contact me at (301) 415-8548.
Sincerely, original signed by:
Diane T. Jackson, Project Manager Standardization Project Directorate l
Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No.52-003
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Enclosure:
As stated cc w/ enclosure:
See next page DISTRIBUTION:
- Enclosure to be held for 30 days
- Docket File PDST R/F MSlosson PUBLIC SWeiss TRQuay TKenyon BHuffman JSebrosky DJackson JMoore, 0-15 B18 WDean, 0-17 G21 ACRS (11)
CBerlinger, 0-8 H7 EThrom, 0-8 H7 GHolahan, 0-8 E2 DOCUMENT NAME: A:W14845 2.RAI T3 esceive e copy of thee alocuenent,inecate"h the ben: "C" = Copy without attachment / enclosure
'E' = Copy with attachment / enclosure
- N" = No copy 0FFICE PM:PDST:DRPM _
D:PDST:DRPM l l
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NAME DTJackson:sg LW TRQuay T/A DATE 05/b/97
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05/7 /97 0FFICIAL RECORD COPY
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Mr. Nicholas J. Liparulo Docket No.52-003 l
Westinghouse Electric Corporation AP600 l
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cc: Mr. B. A. McIntyre Ms. Cindy L. Haag Advanced Plant Safety & Licensing Advanced Plant Safety & Licensing Westinghouse Electric Corporation Westinghouse Electric Corporation Energy Systems Business Unit Energy Systems Business Unit P.O. Box 355 Box 355 Pittsburgh, PA 15230 Pittsburgh, PA 15230 Mr. M. D. Beaumont Mr. S. M. Modro Nuclear and Advanced Technology Division Nuclear Systems Analysis Technologies Westinghouse Electric Corporation Lockheed Idaho Technologies Company One Montrose Metro Post Office Box 1625 11921 Rockville Pike Idaho Falls, ID 83415 Suite 350 Rockville, MD 20852 Enclosure to be distributed to the following addressees after the result of the proprietary evaluation is received from Westinghouse:
Mr. Ronald Simard, Director Ms. Lynn Connor Advanced Reactor Programs DOC-Search Associates Nuclear Energy Institute Post Office Box 34 1776 Eye Street, N.W.
Cabin John, MD 20818 Suite 300 Washington, DC 20006-3706 Mr. Robert H. Buchholz l
GE Nuclear Energy Mr. James E. Quinn, Projects Manager 175 Curtner Avenue, MC-781 LMR and SBWR Programs San Jose, CA 95125 GE Nuclear Energy 4
175 Curtner Avenue, M/C 165 Mr. Sterling Franks San Jose, CA 95125 U.S. Department of Energy NE-50 Barton Z. Cowan, Esq.
19901 Germantown Road Eckert Seamans Cherin & Mellott Germantown, MD 20874 600 Grant Street 42nd Floor Pittsburgh, PA 15219 Mr. Charles Thompson, Nuclear Engineer AP600 Certification Mr. Frank A. Ross NE-50 U.S. Department of Energy, NE-42 19901 Germantown Road Office of LWR Safety and Technology Germantown, MD 20874 19901 Germantown Road Germantown, MD 20874 Mr. Ed Rodwell, Manager PWR Design Certification Electric Power Research Institute 3412 Hillview Avenue Palo Alto, CA 94303
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REQUESTS FOR ADDITIONAL INFORMATION
~
The following RAls on WCAP-14845, " Scaling Analysis for AP600 Containment During Design Basis Accidents," February 1997, were generated as a result of the April 18, 1997, meeting:
480.1017 The report must be organized in a scrutable manner and the pertinent information must be clearly and unambiguously presented.
In each section the premise on which the analysis is based needs to be stated and followed through in a logical manner to the conclu-i sion.
In its present form, the report is disjointed and lacks focus. Westinghouse should clearly state:
(1) the purpose of each section, and (2) how the material supports the conclusions of the 1
work. The key item is the pressure rate of change equation.
Westinghouse must provide this equation in its final form, together L
with the a groups, in a single location.
)
480.1018 There are three related, and critical, items which must be i
addressed in order to establish that the Westinghouse approach is applict.ble at the scale of the AP600.
1.
The Westinghouse scaling approach does not address the issue that the heat flux in the large scale test (LST) facility is j
too high and that the rate of pressure drop is too high by a factor of eight when compared to the AP600.
The issue is that 4
j Westinghouse did not divide through by the coefficient on the di'/dt term (e.g., Equation (7) on Page xvii of WCAP-14845) in j
the pressure rate of change equation. The key variable of i
concern, in simple terms, is hA/V, where h is the heat transfer coefficient, A is the surface area for heat transfer and V is the containment volume. The governing equations show that this heat flux (Q = hA) to volume ratio is the key quantity that must be preserved, similar to the " power-to-volume" ratio that is used to scale primary system experimental facilities.
With the 1/8 linear scaling of the LST, (hA/V)tsi - 8 (hA/V) moo.
Thus this key top level scaling criteria is not met. This i
needs to be addressed as a major distortion of tha LST, and the 4
i scaling analysis needs to be revised to include this item in the correct manner.
The distortion caused by the difference in hA/V (or Q/V) between the AP600 and the LST is operative in the steady-state and the transient mode. The scaling approach can either divide through by this term, which appears on the left side of the pressure rate of change equation, or the scaling approach can define a dimensionless time and incorporate the term into the rate of change. This is what is done in the Westinghouse analysis. The scaling is then such that dimensionless time proceeds eight times faster in the LST than in the AP600, or looked at it in another way, the heat removal rate per unit volume is eight times higher.
It cannot be argued that the LST Enclosure
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is steady-state and therefore that time is irrelevant.
Even in the steady-state the mixing, diffusion and condensation pro-cesses inside the containment volume and at the shell surface are rate dependent. Data from larger scale facilities is likely to be needed to address this distortion.
2.
Scaling of mixing (circulation) and thermal stratification must be addressed. Data from international test programs, to sup-j plement the LST data, will likely be needed to establish the 1
applicability of the evaluation model at the AP600 scale. Data l
from HDR, Grenoble, and Japanese tests were identified as I
potentially being applicable to address this concern.
3.
The distribution of noncondensibles is a function of scale.
Westinghouse must establish the scaling for the distribution of noncondensibles as they affect condensation heat transfer.
Data from HDR, Grenoble, and Japanese tests were also identi-fied as potentially being applicable to address this concern.
480.1019 Westinghouse has included drops dispersed into the containment atmosphere during blowdown as a heat sink or heat source in the scaling equations.
In the study, the drops are assumed to remain in the atmosphere for all of the double ended cold leg guillotine loss-of-coolant-accident (DECLG LOCA) phases.
This is non physi-cal. The surface area used for the drops is an arbitrary number.
While Westinghouse has argued that the scaling analysis shows that the drops do not have a significant effect, it is recommended that the drops not be included. A thermodynamic equilibrium model is suggested as being more appropriate, as a simpler and acceptable approach. At a minimum, a better discussion of why drops were considered and what conclusions can be drawn from their consider-ation needs to be previded at the beginning of the section.
480.1020 Section 11, on the identification and evaluation of distortions, needs to be supplemented with information which indicates how the distortions are handled when using the LST data to validate the evaluation model. This may include pointers to the PIRT (WCAP-14812) and application (WCAP 14407) reports, as appropriate.
480.1021 The " Conclusions" section of the report, Section 12, must directly and concisely state how Westinghouse uses the results of the scal-ing work.
In particular, 1.
Explain what use is made of the LST data for the WG0THIC com-puter program validation and how does the scaling study support this usage; 2.
Explain how the scaling study used to support the PIRT evalua-tion; and 3.
Explain how the scaling study used to support the use of the various models and correlations in MG0THIC at the scale of i
AP600.
2