ML20129J293

Submits Technical Staff Positions on Three Major Issues Resulting from Civil Engineering & Geosciences Branch Review of Westinghouse AP600 Advanced Reactor Design

ML20129J293
Person / Time
Site:	05200003
Issue date:	11/04/1996
From:	Quay T NRC (Affiliation Not Assigned)
To:	Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
References
NUDOCS 9611060199
Download: ML20129J293 (4)

Text

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UNITED STATES S

NUCLEAR REGULATORY COMMISSION E

\\.....[f WASHINGTON, D.C. 20086 0001 November 4, 1996 Mr. Nicholas J. Liparulo, Manager Nuclear Safety and Regulatory Activities Nuclear and Advanced Technology Division Westinghouse Electric Corporation P.O. Box 355 Pittsburgh, Pennsylvania 15230

SUBJECT:

THREE MAJOR ISSUES RESULTING FROM THE CIVIL ENGINEERING AND i

GEOSCIENCES BRANCH (ECGB) REVIEW OF THE WESTINGHOUSE AP600 ADVANCED REACTOR DESIGN

Dear Mr. Liparulo:

As a result of the Nucleer Regulatory Commission ECGB review of the seismic l

design of the AP600 nuclear island structures (including the foundation mat), and the leak-before-break issue, three major issues were identified. These issues are documented in the draft safety evaluation report for the AP600 design,' and have been discussed extensively with the Westinghouse staff.

Because of the different viewpoints between the staff and Westinghouse, and in order to meet overall review schedule, the staff indicated the possible resolution for these items.

Provided below is the technical staff's positions on the three issues.

l 1.

Site Conditions - Shallow Soil Site The staff position is that the AP600 seismic design capacity could be established through the use of a sufficient and necessary set of minimum seismic design response spectra, including the free field and in-structure response spectrum l

i envelopes, by the combined license applicant to complete its seismic design l

within the scope of certified design. Suitability of a future site would then have to be established by demonstrating that the seismic demand spectra for the site are lower than the capacity spectra.

As with other design acceptance criteria, the result will be non-standard seismic design for certain systems (e.g., piping).

l l

There are three options for Westinghouse to consider for resolving this issue:

Westinghouse AP600 could adopt the design site specific response spectrum a.

(DSSRS) approach used for the System 80+ reactor design. The suitability of a future site would then be established through a simple comparison of l

DSSRS and the site specific response spectrum.

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b.

The standard safety analysis report (SSAR) could state that the AP600 is i

t not designed for shallow soil sites, i.e., the approved site parameter excludes shallow soll sites.

g c.

The SSAR could specify a separate design parameter for shallow soil sites i

and evaluate the design against that parameter, e.g., 0.2g with Regulatory Guide (RG) 1.60 design response spectra.

060068 BC 31CMTS W 9611060199 961104 PDR ADOCK 05200003 A

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Mr. Nicholas J. Liparulo November 4, i996 m

2.

Design of the Containment Foundation Basemat 2

The issue of the existence of collocated hard and soft espots'in s~ oil has not surfaced. for other standard designs because it had no. safety" impact' on'their foundation design. Currently, the thinness of the AP600 basemat, even with the..5 consideration of additional shear reinforcement, make. it unacceptable for the 'i,

• i likely soil stiffness variability that can be reasonably expected toLexist a; site. Additionally, cc,nsidering the basemat design.as a COL action item is not '-

acceptable.

i There are two options for Westinghouse to consider for.' resolving this_ issue, j

Demonstrate that the final foundation basemat design can' accommodate the l

i a.

effects of soil stiffness variations of hard and soft spots underneath the i

basemat.

f b.

Use different basemat thicknesses for a foundation with uniform foundation stiffness (such as rock sites) and for a foundation with non-uniform soil stiffness (such as soil sites with hard and soft spots).

Submit the completed design of each basemat thickness for the staff review and i

approval.

3.

Application of Leak-Before-Break (LBB) to feedwater Lines Since the potential for water hammer cannot'be ruled out, and Westinghouse has not provided a quantitative analysis demonstrating an extremely low probability l

l of this event, the staff has concluded.that the criteria in general design criteria-4 (GDC-4), i.e. the probability of pipe rupture due to water hammer is extremely low, has not been met. The staff concludes that application of LBB to j

4 the feedwater line for the AP600 is unacceptable.

l If you have any questions regarding this matter, you can contact Diane Jackson at (301) 415-8548.

Sincerely, I

original signed by:

Theodore R. Quay, Director Standardization Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No.52-003 cc: See next page DISTRIBUTION:

See next page DOCUMENT NAME: A:3MAJISS n

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NAME-DTJackson:sgT)g GCLMnas TRQuay 18 W DATE 10/3//96 V

19/I/96 10/ 4 /96 0FFICIAL RECORD COPY' 1

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Mr. Nicholas J. Liparulo Docket No.52-003 l

Westinghouse Electric Corporation AP600 cc: Mr. B. A. McIntyre Mr. Ronald Simard, Director l

Advanced Plant Safety & Licensing Advanced Reactor Programs l

Westinghouse Electric Corporation Nuclear Energy Institute l

Energy Systems Business Unit 1776 Eye Street, N.W.

i P.O. Box 355 Suite 300 Pittsburgh, PA 15230 Washington, DC 20006-3706 Mr. John C. Butler Ms. Lynn Connor i

l 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 Mr. James E. Quinn, Projects Manager i

LMR and SBWR Programs Mr. M. D. Beaumont GE Nuclear Energy

'1 Nuclear and Advanced Technology Division 175 Curtner Avenue, M/C 165 l

Westinghouse Electric Corporation San Jose, CA 95125 One Montrose Metro 11921 Rockville Pike Mr. Robert H. Buchholz Suite 350 GE Nuclear Energy Rockville, MD 20852 175 Curtner Avenue, MC-781 1

San Jose, CA 95125 i

Mr. Sterling Franks U.S. Department of Energy Barton Z. Cowan, Esq.

NE-50 Eckert Seamans Cherin & Mellott 19901 Germantown Road 600 Grant Street 42nd Floor Germantown, MD 20874 Pittsburgh, PA 15219 Mr. S. M. Modro Mr. Ed Rodwell, Manager Nuclear Systems Analysis Technologies PWR Design Certification Lockheed Idaho Technologies Company Electric Power Research Institute Post Office Box 1625 3412 Hillview Avenue Idaho Falls, ID 83415 Palo Alto, CA 94303 Mr. Frank A. Ross Mr. Charles Thompson, Nuclear Engineer l

U.S. Department of Energy, NE-42 AP600 Certification Office of LWR Safety and Technology NE-50 19901 Germantown Road 19901 Germantown Road Germantown, MD 20874 Germantown, MD 20874 i

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DISTRIBUTION:

Letter to Mr. Nicholas J. Linarulo. Dated: November 4, 1996

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