ML20138B752
| ML20138B752 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 04/25/1997 |
| From: | Diane Jackson NRC (Affiliation Not Assigned) |
| To: | Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| References | |
| NUDOCS 9704290262 | |
| Download: ML20138B752 (7) | |
Text
..
i.
April 25,1997
-Mr. Nicholas J. Liparulo, Manager
. Nuclear Safety and Regulatory Activities Nuclear and Advanced Technology Division Westir + use Electric Corporation P.O.
355 Pittst wh, Pennsylvania 15230 j
SUBJECT:
REQUESTS FOR ADDITIONAL INFORMATION (RAls) FOR NEW ITEMS AND EXIST-ING OPEN ITEMS ON THE AP600 ADVANCED REACTOR DESIGN
Dear Mr. Liparulo:
The Nuclear Regulatory Commission (NRC) staff has determined that it needs additional information in order to complete its review of the Westinghouse i
AP600 advanced reactor design. is (RAIs# 231.35 - 231.40) regard-ing the staff's review of the Westinghiuse standard safety analysis report (SSAR) Revision 11 and the submittal dated March 26, 1997, which provided draft SSAR Revision 12. is requests for information or documenta-tion needed to resolved existing open items.
i If you have any questions regarding this matter, you may contact me at
-(301) 415-8548.
Sincerely, original signed by: Joseph M. Sebrosky Diane T. Jackson, Project Manager Standardization Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No.52-003
Enclosures:
As stated cc w/ enclosures:
See next'page j
DISTRIBUTION:
Docket File PDST R/F TMartin PUBLIC.
MSlosson TRQuay TKenyon BHuffman JSehrosky DJackson JMoore, 0-15 B18 WDean, 0-17 G21 4
i ACRS (11)
BSheron 0-7 D26 GBagchi 0-7 H15
@D RPichumani 0-7 H15 TCheng 0-7 H15 CLi, 0-8 D1 LMarsh, 0-8 D1 NBC rte CENTER COPY 200043
' DOCUMENT'NAME:' A:CH2.RAI n *..
.e== w.me mm.wm ;c 4cm mow m m.nci
. cm
.cwn.nu.new... w. u..
OFFICE PM:PDST:DRPM BCMiE:DE D:PDST:DRPM')
l l
~
NAME DTJacksonJM:;GT Wag @i TRQud9 /& ci DATE 04/79979 64/.J,/97 -
04/if/gl'/ f
0FFICIAL RECORD COPY 9704290262 970425 PDR ADOCK 05200003 A
1 i
f Mr. Nicholas J. Liparulo Docket No.52-003 Westinghouse Electric Corporation AP600 cc: Mr. B. A. McIntyre Mr. Ronald Simard, Director Advanced Plant Safety & Licensing Advanced Reactor Programs Westinghouse Electric Corporation Nuclear Energy Institute Energy Systems Business Unit 1776 Eye Street, N.W.
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 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 Suite 350 GE Nuclear Energy Rockville, MD 20852 175 Curtner Avenue, MC-781 San Jose, CA 95125 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 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
_ _ - ~ -. - - -.. -
- ~.
REQUESTS FOR ADDITIONAL INFORMATION CIVIL ENGINEERING AND GEOSCIENCES BRANCH WESTINGHOUSE AP600 SSAR SECTION 2.5 RAI #231.35
- Section 2.5.4.5.2.1 (page 2-11, 3rd line from bottom) of the SSAR (revised after Revision 11) states that a series of borings should be drilled on a grid pattern that encompasses the nuclear island footprint and 40 feet beyond the boundary of the footprint. The basis for the proposed 40-foot limit should be explained. The limit should be about one-third to one-half of the length /
width of the nuclear island (which measures 256 feet in length and about 160 feet in width).
This is RAI #231.35 in SSAR 2.5.4.5.
RAI #231.36 Section 2.5.4.5.2.1 () age 2-12, first paragraph, loth line) states that at least one-fourth of tie primary borings should penetrate soand rock, or for deep soil sites, to a maximum depth, d,,,, taken as the depth at which the vertical stress during or after construction for the combiaed foundation loading is less than 10-percent of in situ effective overburden stress. Other borings may terminate at a depth of 160 fect below the foundation (equal to the width of the structure). This SSAR commitment of Westinghouse is not acceptable because the depth at which the borings are stopped should depend on the suspected presence or absence of compressible materials or the suspected presence of voids (i.e. sinkhole, etc.) below the nuclear island footprint.
The 160-foot limit should be changed to at least 200 feet (which is approxi-mately equal to the " side" of the equivalent square of the nuclear island footprint). This is RAI #231.36 in SSAR 2.5.4.5.
RAI #231.37 A review of pages 2-12 and 2-13 in Section 2.5.4.5.2.1 (revised after Revi-sion 11) indicates that, to establish the " uniformity" of a site, there are three criteria that the site must satisfy:
(1) the uniformity of the layer thickness (layers must be uniform), (2) the dip angle of the layer (maximum 1
20 degrees), and (3) uniformity of shear wave velocity within any layer
~
(variation must be less than.10 or 20 percent of the layer average).
In addition, there seems to be twe other criteria discussed in the third and fourth paragraphs of page 2-12, and in pages 2-14 and 2-15: (4) the depth of a given layer must not deviate by more than 5 percent of the depth of the "best estimate" plane for the layer, and (5) any undulatory bed rock must be at least 40 feet below the bottom of the basemat. Westinghouse should clearly state these five acceptance criteria together in the SSAR.
The lengthy discussion of the draft revision is very confusing and is likely to lead to a misinterpretation.
The procedure for establishing the acceptability of AP600 design for non-uniform sites should also be established.
In addition, for the site to be acceptable as an uniform site, the last paragraph of page 2-12 of i
the revised SSAR states that the variation of the shear wave velocity in the
~
material below the foundation to a depth of 80 feet below the basemat within the footprint of the plant shall meet the criteria specified on Page 2-13 of the revised SSAR. Westinghouse should justify the basis for the 80-foot 4'
limit. This is RAI #231.37 in SSAR 2.5.4.5.
s e
4
. RAI #231.38 The statement made in Section 3.8.5.4.3 of the SSAR (revised after Revi-sion 11) concerning the construction-induced stresses is not acceptable.
During the previous review meetings, the staff has indicated that the basemat stresses induced by construction settlements can be additive to the basemat stresses induced by other design basis loads.
It is not proper to treat these stresses as secondary or self-relieving stresses. The settlement-induced stresses can be additive at some locations depending on the construction sequence remaining, the geometry of the structure, and the sense of the induced moments and shears developed in the basemat.
In the December 9 through 13, 1996, meeting, Westinghouse was requested to provide information on those issues typically encountered during construction of large structures (stress relief and expansion due to excavation, effective stress increase and settlements from dewatering effects, and long term consolidation effects on the settlement time history). The staff also requested Westinghouse to provide a possible use of a limitation on the anticipated construction for definition of an adequate site. However, the information has yet to be provided.
In addition, the analyses performed by Westinghouse are based on two-dimensional analyses and only considered the effect of immediate settle-ments on construction-induced stresses.
Even then, Westinghouse's calcula-tions indicated that these stresses are sensitive to the particular sequence of construction assumed. The effects of settlement time history were not evaluated.
Furthermore, the conversion of two dimensional to three dimension-al (real world) effects used an unusually large factor to reduce the predicted bending moments and shears of the basemat without a proper justification. The adequacy of using this reduction factor needs to be demonstrated by Westing-house. This is RAI #231.38 in SSAR 2.5.4.3.
RAI #231.39 In Section 2.5.4.5.2.2 of the SSAR (revised after Revision 11), Westinghouse indicates that if a site is classifird as non-uniform based on the criteria listed on the top of Page 2-13, the investigative effort should be extended in such a way that the site may be demonstrated to be acceptable for AP600 by l
showing that the in-structure response spectra are enveloped by the design instructure response spectrum envelopes. However, it should be clearly stated 4
in the SSAR that the demonstration must specifically include a complete reevaluation of the soil-structure interaction effects for this non-uniform site, because all soil-structure interaction analyses (2D or 3D) performed by 4
Westinghouse were based on uniformly bedded site profiles.
The staff, in several review meetings, has raised the concern regarding how the effect of local hills and valleys of the bed rock (or competent material) need to be included in the evaluation. The staff's concern is that these non-uniform conditions would serve to change the input free-field ground motions coming into the site (e.g., local amplification effects). This is RAI #231.39 in SSAR 2.5.4.5.
' RAI# 231.40 Section 2.5.4.5.5 (page 2-16) of the SSAR (revised after Revision 11) states that for sites with soil characteristics outside the range considered in Appendices 2A.2, and 28.2, the COL applicant may use the site-specific soil conditions and site-specific SSE, and perform site-specific SSI analyses, and demonstrate acceptability (of the site) by comparing the floor response spectra at specified locations. A similar statement permitting the COL applicant to perform a site-specific seismic analysis of the nuclear island is made in Section 2.5.4.5.2.2 (Acceptance criteria for non-uniform sites). The proposed revision is not acceptable to the staff. The SSAR should state that such sites are not covered by the certified design. This is RAI #231.40 in SSAR 2.5.4.5.
RAl# 231.41 Table 2-1 (page 2-19) of draft Revision 12 must be revised to state that SSE site parameter is 0.30g PGA, except that shallow soil sites are excluded.
Also, include a COL requirement for excluding shallow soil sites in Section 2.5.2.1 of SSAR.
RAI# 231.42 Figure 2.5-1 (page 2-23) of draft Revision 12 must be deleted or revised.
Presumed margins are not included in site parameters.
Also Section 2.5.2.2 of 1
the SSAR must be revised.
The review criteria are unacceptable.
Open Items that Require Additional Information Scan Item 2.5.4.3-2 In response to this open ites, Westinghouse provided estimates of total settlements and heave in SSAR Rev.5 Table 2.3, which has been deleted in SSAR draft Rev. 12, dated March 26, 1997. However, in the same draft Revision 12, Westinghouse states that, based on its short term and long term heave and settlement of the NI foundation, "the maximum settlement after placement of first concrete for the basemat is 4 inches for the alternating sand and clay site and 12 inches for the all clay site."
These settlement-values are much larger than those given in the deleted Table 2.3, which had a maximum value of only 1.28 inches. Westinghouse should clarify the discrepancy between the lower total settlement and heave values given in the old Table 2.3 and the higher maximum settlement values given ta draft Revision 12. This item remains open.
Open Item 2.5.4.3-2 Dr a telephone conference with the staff on May 1,1996, and in its June 5,1996, letter to NRC, Westinghouse has stated that differential settlement between the nuclear island and surrounding buildings does not have an adverse effect on safety-related functions.
For the main steam lines and the main feedwater lines, anchors located at the exterior walls of the auxiliary building preclude transfer of loads due to differential settlement into the safety related portions of the lines. Westinghouse has further stated that the flexibility of the lines in the turbine building minim'.zes the loads due to differential settlement in the non-safety related portion of the lines. However, as agreed during the telephone conference on May 1, 1996, Westinghouse should clarify in the
]
SSAR Section 3.8.5 that the NI basemat will be designed and constructed giving due consideration to the effects of construction sequence.
Therefore this item remains open.
Open Item 2.5.4.4-1 Westinghouse has considered the effects of groundwater at different depths by performing SSI studies with water table depths assumed at 0 m (0 ft) (ground surface),12.2 m (40 ft) (bottom of base slab), and very deep depths. During discussions with the staff, Westinghouse stated that, in the SASSI calculations, the effect of the ground water was incorporated by using the strain-dependent shear wave velocity determined from the SHAKE calculations while maintaining the compressional wave (P-wave) velocity at 1524 m/sec (5000 fps). Westinghouse further stated, in the May 16, 1994, response to Q231.27, that the water table location was considered in the SSI analyses by adjusting the Poisson's ratio of the submerged soil layers, if necessary, so that, in conjunction with the strain-compatible shear wave velocity, the minimum P-wave velocity of 1524 m/sec (5000 fps) is retained. However, the staff noted during an audit that dry soil densities were used in the SSI analyses using the SASSI code. Westinghouse was asked to indicate in the SSAR that this procedure was used in the SSI analyses, and that the effects of using the dry soil densities for saturated soil conditions are small. At a subsequent y
i i
l i
l
. meeting with the staff, Westinghouse presented analytical data to show that the effects of using dry soil densities on structural responses were not significant.
In its June 5, 1996, response, Westinghouse proposed a revision of the SSAR stating that it did not adjust the densities for the i
cases where the water table was shallow, and further stating that the effect of using the total density for saturated soils on the dynamic soil properties is negligible. Closure of this item is pending Westinghouse documentation, in the SSAR, the results that show the negligible effects of using dry soil densities for saturated soils on the dynamic soil properties and on the structural responses.
i