ML20041G553
| ML20041G553 | |
| Person / Time | |
|---|---|
| Site: | Skagit |
| Issue date: | 03/11/1982 |
| From: | Adensam E Office of Nuclear Reactor Regulation |
| To: | Spangenberg F NORTHWEST ENERGY SERVICES CO. |
| References | |
| NUDOCS 8203220513 | |
| Download: ML20041G553 (5) | |
Text
.t DISTRIBUTION:
D R 1 1 1332 e Docket Nos.w50-522/523 LB #4 r/f DEisenhut Docket hos: 50-522 EAdensam bcc: TERA and 50-523 MMallory NRC/PDR MDuncan Local /PDR SHanauer NSIC Mr. Frank Spangenberg RTedesco TIC Assistant Project Manager - Nuclear RVollmer ACRS (16)
Northwest Energy Services Company JKramer 2320 Northup Way RMattson Bellevue, Washington 98004 RHartfield, MPA OELD
Dear f1r. Spangenberg:
OIE (3)
Subject:
Request for Additional Information - Skagit/Hanford Nuclear Project In order that we may continue our review of your application for permits to con-struct the Skagit/Hanford Nuclear Project, Units 1 and 2, your response to the enclosed request for additional information is required.
To maintain our licensing review schedule we require a completely adequate response to the enclosure by liarch 23, 1982. Please inform us within 7 days af ter receipt of this letter whether or not you will be able to respond by March 23, 1982.
Please contact the licensing project manager, Mike Mallory, at (301) 492-4449 if you desire additional discussion or clarification of the information requested.
The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore, OMB clearance is not required under P.L.96-511.
Sincerely,
/Elinor G. Adensan, Chief Licensing Branch No. 4 Division of Licensing l
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SKAGIT Mr. J. E. Mecca, Manager Nuclear Licensing & Safety Puget Sound Power Light Co.
Puget Power Building Bellevue, Washington 98009 cc: Mr. F. Theodore Thomsen Mr. Russell Jim Perkins, Coie, Stone, Olsen Tribal Councilman
& Williams Consolidated Tribes and Bands 1900 Washington Building Yakima Indian Nation Seattle, Washington 98101 P.O. Box 151 Toppenish, Washington 98948 Mr. Robert lowenstein Lowenstein, Newman, Reis Robert Engelken, Regional Administrator
& Axelrad U.S. Nuclear Regulatory Consnission, Suite 1214 Region V 1025 Connecticut Avenue, N.W.
1450 Maria Lane, Suite 210 Washington, D. C.
20036 Walnut Creek, California 94596 Roger M. Leed, Esq.
Mr. Frank Spangenberg Law Of fices Assistant Project Mana.ger - Nuclear 1411 4th Avenue Northwest Enargy Services Company Seattle, Washington 98104 2820 Northup Way P.O. Box 1090 Mr. Lloyd K. Marbet Kirkland, Washington 98033 c/o Forelaws on Board 19142 South Bakers Ferry Road Boring, Oregon 97009 Mr. Nicholas D. Lewis, Chairman Energy Facility Site Evaluation Council 820 East 5th Avenue Olympia, Washington 98504 Honorable Richard Sandvik Department of Justice 500 Pacific Building 520 Southwest Yamhill Portland, Oregon 97204 Coalition for Safe Power Governor Building - Suite 527 I
408 S.W. Second Avenue Portland, Oregon 97204 e
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r Request for Additional Information - Geotechnical Engineering '
Skagit/Hanford Nuclear Project, Units 1 and 2 Docket No. 50-522 0241.1 In Amendment 23, section 2.5.4 to the PSAR, the applicant has proposed (2.5.4) to support the common foundation mat for the seismic Category I structures about 20 ft below existing (and final) ground surface (plant grade) at elevation 507 (El 507), on Missoula sediments that occur between about El 520 and El 495.
Plant grade is at El 527.
The Missoula sediments are described as medium dense to dense, clean medium sand, gray to black.
Field tests in these soils showed Standard Penetration Test-(SPT) values ranging from about 10 to 40
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blows /ft (PSAR Fig. 2QA-1 th' rough 37 and Table 2QB-1).
Below El 507 the SPT values were generally greater than 20 blows /ft.
The underlying Pre-Missoula sediments, between about El 495 and El 480 are described as very dense, silty fine sand, dark yellowish-brown to olive gray. The SPT values in the Pre-Missoula sediment were generally on the order of 100 blows /ft.
These soils are underlain by dense to very dense sand and gravel (SPT values greater than 45 blows /f t).
Based on our review of the applicant's submittals, it is our opinion that the Missoula sands in their present condition'are not suitable for the direct support of seismic Category structures because the in-place densities are variable and, in some cases, too low to assure satisfactory structural support.
Additionally, the proposed foundation support conditions are significantly inferior to the conditions adopted (and found by the staff to be acceptable) at the nearby Washington Public Power Supply System Unit 2 (WNP-2).
The factors supporting our conclusion are as follows.
l.
The lower SPT values recorded below proposed foundation level (17 to 23 blows /ft near Unit 1,13 to'22 blows /ft near Unit 2) correlate to relative densities near 'or below 60% (PSAR Figs.
2QA-38 and 39). 'The in-place relative densities may, in fact, be near or below 50% according to recent studies by the Waterways Experiment Station (ASCE Journal, GT-ll,' November 1977, page 1295).
2.
The applicant determined in-place relative densities of 9% to 53% in the exploratory trenches (PSAR Table 2QB-6). The applicant suggested that the tests were not representative because of soil layering.
We believe that they hre also indicativ.e of loose, unsuitable in situ soil conditions.
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At the WNP-2 site, shallow sands having STP values generally in the range of 15 to 40 blows /ft were judged to have relative densities in the range of 30 to 50% (UNP-2 FSAR, App. 2.5F, Figs. 4 and A-3 throughA-7).
These soils were excavated to a depth of about 40 ft i
below grade and recompacted to about 80% relative density in order to provide suitable foundation support.
Based on the applicant's submittals and a telephone discussion between the staff and the applicant on March 2,1982, we understand that the applicant concluded that the Missoula sands are suitable for foundation support based on the following factors.
1.
The average SPT values of 25 to 30 blows /ft and corresponding relative densities of 75% to 80% are within ranges that will provide suitable foundation support and that the large, thick foundation mats will distribute structural loads over local, loose pockets.
2.
The plate load. tests in the exploratory trenches show relatively high elastic modulus values for the Missoula sands-(10,000 psi to 20,000 psi) so that calculated se.ttlements of structures under static loads are wall.
3.
The geophysical studies show relatively high shear wave velocities
-(900 ft/sec) in the Missoula sands so that calculated settlements of structures under earthquake loads are small..
4.
The applicant believes that removing and recompacting the Missoula sands may not produce improved densities in the bearing soils.
We find that the applicant's informati,on and byaluation does not resolve our concern for the suitability of the in-place Missoula sand as a foundation bearing material.
Thus, we ask that the applicant submit an alternative to the presently proposed plan that has seismic Category I foundations supported directly in the in situ Missoula sand.
For guidance, the applicant should refer to the WNP-2 foundation construction wherein medium dense to dense sands were excavated to a depth of about 40 ft (down to dense sand) and foundation elevations were re-established by use of structural backfill. The staff found this procedure to be acceptable for the WNP-2.
Q241.2 Table 2L-5 shows "P" wave and "S"' wave values and calculated Poisson's (App 2L) ratio values that appear to be inconsii; tent.
Provide a discussion of the bases for the acceptability of these design values.
3)241.3 Provide a description of the anticipated bearing co'nditions and bedding
( 2. 5. 4.' 5 )
details for soil-supported seismic Category I pipes and conduits.
Provide a s'ummary of the specifications for bedding and backfilling.
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0241.4 Provide a correlation between the seismic Category I structures listed-(2.5.4.5) under "B.
Other Structures" on Sheet 22 of Table 3.2-1 and the numerical listing on Figure 1.2-1.
Identify the proposed foundation elevations and conditions of any seismic Category I structures that are not shown on Figure 2.'5-15.
Q241.5 Provide a commitment to notify the NRR staff in advance of the (2.5.4.5) completion of foundation excavations so that the staff may inspect the excavations.
0241.6 Provide a description of the procedures that will be adopted to (2.5.4.5) protect and maintain temporary soil slopes and to provide adequate drainage around structures so as to assure that foundation soils will not be damaged by local heavy rains and erosion during construction.
Include a description of the periodic inspection procedures that will assure proper maintenance of temporary slopes and drainage facilities.
Q241.7 Discuss the efficacy of using the Proctor method (ASTM D-1557) for (2.5.4.5) field density control of the clean sands in view of the testing difficulties encountered during the exploration, as described on page 2QB-4.
Propose alternatives.for field control of; backfill.
.Q241.8 Specify the gradation limits that will be acceptable for structural (2.5.4.5 backfill material.
Also describe how the excavated soils that are used for backfilling will be mixed and blended to provide homogeneity; that is, describe how problems with obtaining relative density values in ccmpacted fill will be avoided in view of the problems encountered with determining relative density in the exploratory test trenches (see page 2Q-ll, page 2Q-14 and Table 2QB-6).
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