ML20134G262
| ML20134G262 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 10/02/1996 |
| From: | Quay T NRC (Affiliation Not Assigned) |
| To: | Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| References | |
| NUDOCS 9611130110 | |
| Download: ML20134G262 (4) | |
Text
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h aG49k UNITED STATES
[
S NUCLEAR RE2ULATORY COMMISSION WASHINGTON, D.C. 20066-0001 k*****
b October 2, 1996 l
l l
Mr. Nicholas J. Liparulo, Manager i
Nuclear Safety and Regulatory Activities Nuclear and Advanced Technology Division i
Westinghouse Electric Corporation i
l P.O. Box 355 Pittsburgh, Pennsylvania 15'230
SUBJECT:
REVIEW OF AEROSOL REMOVAL MECHANISMS IN THE AP600 CONTAINMENT FOLLOWING A POSTULATED DESIGN BASIS ACCIDENT
Dear Mr. Liparulo:
In your letter dated August 5,1996, Westinghouse provided a technical position paper on aerosol removal from the AP600 containment atmosphere following a postulated design basis accident.
In the cover letter, Westing-house stated that "... providing additional, arbitrary conservation by reducing the calculated aerosol removal rate [by the staff] is unnecessary and is inconsistent with the objective of NUREG-1465 to provide more realistic portrayal of the amount of fission products present in the containment."
As stated in its July 17, 1996 letter, the staff has not yet established its technical position on this matter for the AP600 design described en the docket. The information provided in that letter was given to help you understand the concerns of the staff and its contractor on this issue.
The i
staff may elect to use information from a variety of sources (including contractors) in its technical evaluations; however, as stated in the July 17, l
1996 letter, the staff has not completed its review of this matter. The staff will make the final determination on its assessment of the appropriate aerosol removal rates in the AP600 containment, and the technical bases used for such determination will be provided in the forthcoming AP600 safety evaluation.
However, it is the understanding of the staff from Westinghouse's August 8, I
1996, presentation to the Advisory Committee on Reactor Safeguards and recent discussions with your staff that Westinghouse has modified certain parameters provided to the staff in your letter dated April 7,1995, in response to l
request for additional information (RAI) Q470.23, and, therefore, Westinghouse may have modified its design of the AP600. The staff will recalculate aerosol i
I removal rates using the revised parameters provided by Westinghouse. There-fore, because this matter is still under review by the staff, we believe that I
l the aforementioned conclusion by Westinghouse is premature.
The staff agrees with Westinghouse that the values proposed in NUREG-1465 are realistic and reflect best estimates for the range of plants and sequences considered. The staff is proposing to use the fission product release fractions, release timing, and its chemical forms from the NUREG for the AP600 i
design certification review. However, while these values are realistic and best estimate treatment may be appropriate for severe accident considerations,
/
080061 9611130110 961002 PDR ADOCK 052000 2
Mr. Nicholas J. Liparulo October 2, 1996 1
the staff concludes that the use of realistic assumptions for the entire design basis accident evaluation may not be appropriate because of the uncertainties that remain, l_
In addition, in a letter from the Electric Power Research Institute (EPRI) to the Chairman, " Policy Issues Pertaining to the AP600 Design," dated August 27, 1996, EPRI stated that "... very recent discussion between Sandia (Sandia National Laboratories," Albuquerque, NM] and Westinghouse is expected to lead l
to some refinement of the Sandia input to the NRC..."
If Westinghouse, Westinghouse's contractors, EPRI, or EPRI's contractors who work on the AP600 i
l project discussed these matters with an NRC technical contractor (Sandia National Laboratories) outside of a public forum and not incidental to, for example, a chance encounter, provide a detailed summary of discussions held.
l These must be made part of.the record and will be made available to the public..
Enclosed is a RAI (Q470.38 - Q470.40).that must be satisfactorily addressed in order for the staff to complete its review of this issue.
If you have any questions or comments regarding these' matters, you can contact the Project Manager, Thomas Kenyon, at (301) 415-1120.
Sincerely, l
original signed by:
Theodore R. Quay, Project Director Standardization Project Directorate l
Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No.52-002 i
Enclosure:
As stated cc w/ enclosure:
l See next page l
DISTRIBUTION:
- HOLD FOR 30 DAYS
- Docket File PDST R/F TMartin
- PUBLIC TQuay TKenyon DJackson BHuffman JSebrosky l
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REmch, 0-10 D4 JLee, 0-10 D4 BZaleman CBerlinger, 0-8 H7 JKudrick, 0-8 H7 MSnodderly, 0-8 H7 l
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OFFICIAL RECORD COPY j
l l
k' Mr. Nicholas J. Liparulo Docket No.52-003 Westinghouse Electric Corporation AP600 I
cc: Mr. B. A. McIntyre Mr. John C. Butler 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 Letter to be distributed to the following addressees after the result of the propri-etary evaluation is received from Westinghouse:
Mr. Ronald Simard, Director Ms. Lynn Connor i
l Advanced Reactor Programs DOC-Search Associates Nuclear Energy Institute Post Office Box 34 l
1776 Eye Street, N.W.
Cabin John, MD 20818 Suite 300 Washington, DC 20006-3706-Mr. Robert H. Buchholz 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 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 l
Office of LWR Safety and Technology Germantown, MD 20874 l
19901 Germantown Road l
Germantown, MD 20874 Mr. Ed Rodwell, Manager PWR Design Certification Electric Power Research Institute 3412 Hillview Avenue Palo Alto, CA 94303 1
i
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REQUEST FOR ADDITIONAL INFORNATION ON THE AP600 DESIGN The technical bases provided in your August 5,1996, submittal rely on (1) standard textbook formulae for sedimentation, diffusiophoretic, and thermophoretic processes, (2) aerosol removal coefficients calculated by Westinghouse for the initial period after onset of core damage and for the remainder of the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of the accident, and (3) the STARNAUA code 1
dated February 23, 1996.
In order to complete our review, the staff needs the l
following additional information concerning natural aerosol removal mechanisms in the AP600 containment:
470.38 Provide a description of the models used in the version of the STARNAUA code used by Westinghouse to calculate aerosol removal rates, associated user documentation, and the code inputs used and I
outputs obtained in calculating the aerosol removal coefficients (landas).
In addition, the staff requires access to this version of the code, including the code validation and verification (V&V) and quality assurance (QA) documentation.
l l
In your letter dated August 5, 1996, Westinghouse stated that the STARNAUA code was specifically validated against mod. 4 of the NAUA code for the case of no steam condensation on particles or walls, and validated against the NAVAHYGROS code for both dry and wet cases. The staff requires access to these specific validation reports as well.
j 470.39 Provide aerosol removal coefficients as a function of time and the uncertainty distribution for each time step (0.1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />) after the l
postulated design basis accident over the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
470.40 In your letter dated August 29, 1996, Westinghouse updated its assumptions for aerosol sedimentation area available inside the AP600 containment. For each floor and heat sink sedimentation l
area, provide the corresponding elevation, isometric drawings, and l
vertical separation distances from the adjacent floor and/or heat l
' sink sedimentation area. Additionally, identify impediments I
(e.g., structures) to full circulation through such volumes.
1 f
Enclosure
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