ML20209C285
| ML20209C285 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 07/15/1983 |
| From: | Heller L Office of Nuclear Reactor Regulation |
| To: | Kuo P Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML16340C148 | List:
|
| References | |
| FOIA-86-151 NUDOCS 8307250043 | |
| Download: ML20209C285 (26) | |
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j JUL 151983 Docket No. 50-275 MEMORANDUM FOR: Pao-Tsin Kuo, Leader Structural Engineering Section B Structural and Geotechnical Engineering Branch Division of Engineering THRU:
George Lear, Chief 1g3 Structural and Geotechnical Engineering Branch Division of Engineering FROM:
Lyman W. Heller, Leader Geotechnical Engineering Sec~ tion Structural and Geotechnical Engineering Branch Division of Engineering
SUBJECT:
GEOTECHNICAL INPUT FOR SUPPLEMENT TO SAFETY EVALUATION REPORT-INDEPENDENT DESIGN VERIFICATION PROGRAM - DIABLO CANYON NUCLEAR POWER PLANT, UNIT 1 Plant Name: Diablo Canyon Nuclear Power Plant, Unit 1 Applicant: Pacific Gas & Electric Licensing Stage: License Suspended and Currently under Review Docket Number: 50-275 Responsible Branch:
LB-3, H. Schierling, LPM Status: Review Continuing Documents Reviewed:
1.
Interim Technical Report, Diablo Canyon Unit 1, Independent Design Verification Program, Soils-Outdoor Water Storage Tanks, Revision 0. ITR #16, by Robert L. Cloud Associates, Inc., December 8.
1982.
2.
Interim Technical Report, Diablo Canyon Unit 1, Independent Design Verification Program, Soils-Intake Structure, Revision 0, ITR #13, by Robert L. Cloud Associates, Inc., November 5, 1982.
3.
Interim Technical Report, Diablo Canyon, Unit 1 Independent Design Verification Program, Soils-Intake Structure Bearing Capacity and Lateral Earth Pressure, Revision 0, ITR #39 by Robert L. Cloud Associates, Inc., February 25, 1983.
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Interim Technical Report, Diablo Canyon Unit 1 Independent Design Verification Program, Soils Report - Intake Structure Sliding Resistance, ITR
- 40, Revision 0, by Robert L. Cloud Associates, Inc., March 9, 1983.
5.
Final Report - Independent Design Verification-Program, Diablo Canyon Nuclear Power Plant Unit 1, by Teledyne Engineering Services, May 31, 1983.
6.
Memo from S. Jagannath to G. Lear, dated July 1983,
Subject:
Audit of Geotechnical Aspects of Diablo
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Danyon Unit 1 Independent Design Verification Program Attac'hed is the geotechnical input for Section 4.5.1' of the subject SSER based on our review of documents referenced above (Reference 1 through 5), a recent technical audit meeting at the offices of Robert L. Cloud Associates Inc. (RLCA) and Brookhaven National Laboratory's summary report. RLCA verified geotechnical aspects of the Outdoor Water Storage Tanks (0WST) and the Intake Structure.
RLCA's review of the 0WST, reported in Reference 1, is acceptable and Harding Lawson Associates's work also meets IDVP criteria and purposes.
i RLCA's review of the intake structure, reported in References 2, 3 and 4, is not present1v accentable. Our concerns were discussed with RLCA during the
, technical audit meeting (Reference 6). RLCA agreed to address the staff's concerns in revised ITRs 13, 39 and 40. Hence, our evaluation of the intake structure for I P is noi complete. We will report.our evaluation in a later supplement after rey ewing the M sed ITRs..
This SSER was prepared by Banad Jagannath, Gc0 technical Engineering Section (49-28368) and incorporates the cannents we have received from the NRC's consultant, Brookhaven National Laboratory.
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n W. Heller, Leader Geotechnical Engineering Section Structural and Geotechnical Engineering Branch Division of Engineering
Enclosure:
As stated cc: See page 3 O
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3-JUL 151983 Pao-Tsin Kuo cc: w/o enclosure R. Vollmer D. Eisenhut w/ enclosure J. Knight G. Lear L. Heller P. T. Kuo H. Polk H. Schierling B. Buckley B. Jagannath 1
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Docket No. 50-275 SSER Input - Geotechnical Engineering Prepared by: Banad Jagannath, SGEB, DE Section 4.5.1 summarizes the staff's geotechnical engineering review of the Diablo Canyon Nuclear Power Plant Unit 1 (DCNPP) as presented in the Final Report of Independent Design Verification Program, dated May 31, 1983 and Interim Technical Reports (ITRs) Nos. 13, 16, 39 and 40, prepared by the Teledyne Engineering Services in response to an order by the NRC. The staff had the benifit of a technical audit of some of the background material refer-enced in the ITRs. Geotechnical work on the Outdoor Water Storage Tanks and Intake Structure have been evaluated against the design criteria used in the DCNPP safety evaluation report (dated October 16, 1974) and its supplements (SSER #1 through 8).
4.5.1 Soils and Foundations 4.5.1.1 Introduction and Scope of Review Phase I of the Independent Design Verification Program (IDVP) for the Diablo Canyon Nuclear Power Plant (DCNPP) deals with the PG & E's internal activities and seismic service-related contracts for the Hosgri qualification analyses, prior to June 1978. Phase I mandated that a sample of piping, equipment, struc-tures and components be selected for independent analysis. Teledyne Engineering Services (TES) is the program manager for this IDVP. Roger F. Reedy, Inc. (RFR) and Robert L. Cloud Associates Inc., (RLCA) are part of the IDVP team under TES.
RFR performed quality assurance (QA) review of PG&E and their seismic service-related contractors which included the firm of Harding Lawson Asso-ciates Inc., (HLA). The QA review revealed that HLA did not implement a QA program for the DCNPP soils work performed for the Hosgri qualification analy-ses prior to June 1978. HLA's geotechnical work included:
intake structure, outdoor water storage tanks, buried diesel' fuel oil tanks and connecting lines, 07/14/83 1
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e and buried auxiliary saltwater piping. As a result of the QA review, RLCA and their consultant, the firm Abendruh, Inc. formulated and carried out a review of HLA's soils work.
In this section the term RLCA represents the TES/RLCA team which carried'out the geotechnical portion of the Independent Design Verification Program.
RLCA selected the following topics and samples of HLA's soils work for an independent design verification.
- 1. Outdoor Water Storage Tanks (0WST) lithology of rock bearing capacity
- 2. Intake Structure lithology and properties of backfill material
-- bearing capacity lateral pressures sliding resistance RLCA reported their findings in a series of Interim Technical Reports (ITRs) and in a final report on the IDVP (Reference 6). ITR #16 presents results of RLCA's review of the 0WST and ITRs #13, 39 and 40 present the results of RLCA's review of the intake structure (Referenace 1,2, 3 and 4 respectively). RLCA also evaluated the effect of lack of QA on HLA's soils work and independently veri-fied HLA's work for Hosgri qualification analyses.
This SSER is based on the documents referenced.
4.5.1.2 Outdoor Water Storace Tanks (0WST)
The OWSTs are situated on the east side of the auxiliary / fuel handling building and are approximately 40 ft in diameter and 50 ft. high. These steel tanks were originally founded on a compacted fill placed over the bedrock.
Following the Hosgri evaluation in 1978, the compacted fill under these tanks was replaced 07/14/83 2
DIABLO CANYON SEC 4.5
e with concrete and the steel tanks were encased in concrete. ITR #16 presents RLCA's review of HLA's geotechnical work for the OWSTs and includes review of lithology of rock and allowable bearing capacity of the bedrock (Reference 1).
Appendix 1 to section 4.5.1 presents the staff's evaluation of ITR #16.
4.5.1.2.1 Lithology of the Rock The geotechnical investigations for the OWSTs performed by HLA in 1973 and 1978 included: borings, laboratory tests on recovered samples and geophysical tests in the borings.
RLCA reviewed information in HLA's reports on the bed-rock depth _(bedrock profile), description of the bedrock and strength proper-1 ties of the bedrock.
4.5.1.2.1.1 Verification of the Bedrock Depth RLCA verified the location of borings and the depth to bedrock by comparing information from HLA's field logs, HLA's reports and PG&E's drawings.
RLCA's verification revealed a discrepancy in the location of two borings. These were addressed in E0I 1101 and E0I 1100 reports and were classified as 'Devia-
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tions' (Class D error). The errors were as a result of incorrect description of structures used as landmark-references in locating the borings. The RLCA recti-fied this error and the location'of the. borings now shown, in the HLA reports, HLA field logs and PG&E drawings are consistent and correct.
The discrepancies in both the location of borings and depth to the bedrock are minor and within variations normally encountered in field explorations. The NRC staff agrees with RLCA's conclusion that HLA's determination of depth to the bedrock at OWSTs was based on consistent set of data and is acceptable.
4.5.1.2.1.2 Verification of Bedrock Description and Strength Parameters RLCA compared the description of the bedrock in HLA's report, in HLA's field l
logs, and in reports by others on previous investigations (Blume studies 1968) l 1969) at this site. RLCA concluded that the description of the bedrock as l
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presented in the HLA's report was consistent with the description given in HLA's field logs and Blume reports.
a The bedrock is moderately weathered, hard, fine to medium grained sandstone and occasional silt stone. HLA assigned strength parameters of 4 ksf for cohesion and 35' for angle of internal friction for the sandstone.
RLCA reviewed the results of two confined compression tests by HLA on samples of moderately to deeply weathered sandstone.
RLCA plotted one test data along with the HLA recommended strength parameters. These two matched very well.
RLCA concluded that the HLA assigned strength parameters are therefore acceptable.
ITR #16 does not present the value of the modulus of elasticity used by HLA in their analysis.
RLCA calculated the modulus of elasticity for the bedrock using data from the geophysical survey performed in general vicinity of the OWSTs and assigned the lowest computed value 500 ksi to the bedrock.
RLCA concluded that the modulus of elasticity (500 ksi) is acceptable for the bedrock in the OWST area.
Although the data base is minimal, the staff judges that the recommended strength parameters are reasonable and are within values generally quoted in the literature for Sandstone. The staff agrees with the RLCA's conclusion.
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l 4.5.1.2.2 Bearina Capacity f
HLA recommended an allowable bearing pressure of 80 ksf for the OWSTs. RLCA independently evaluated the ultimate bearing capacity and concluded that the 80 ksf allowable bearing pressure recommended by HLA for the OWSTs foundation is acceptable. The staff agrees with RLCA's conclusion.
HLA did not estimate the settlement of OWSTs. RLCA calculated the settlement to 1
be 0.5 in. for a maximum bearing pressure of 80 ksf and concluded that the com-puted maximum settlement is not detrimental to the structure. The NRC staff agrees with RLCA's conclusion.
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Evaluation of dynamic loading conditions was not part of HLA's soils work and hence was not selected for review by RLCA.
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4.5.1.3 Intake Structure The intaka structure is a reinforced concrete building founded on a grout mudmat that was poured directly over the bedrock. Three sides of the structure are backfilled to plant grade. The fourth side (west) of the structure has no back-fill and has openings to admit sea water to the intake pumps.
Several years after (in 1978) the intake structure was constructed HLA drilled borings in the backfill material down to the top of bedrock a'nd performed a geophysical survey in these borings to obtain data for the Hosgri evaluation of the DCNPP.
RLCA's review of HLA's work for the intake structure is reported in ITRs 13, 39, and 40.
ITR #13 (Reference 2) reports on lithology and properties of the backfill material.
ITR #39 (Reference 3) reports on the strength and bearing capacity of the rock and the lateral pressures on the walls of the intake structure.
ITR #40 (Reference 4) reports on the sliding resistance of the intake structure. Appendices No. 2, 3 and 4 of section 4.5.1 present the staff's evaluation of ITRs 13, 39 and 46 respectively.
4.5.1.3.1 Lithology of the Backfill Material 4.5.1.3.1.1 Determination of Depth to Bedrock RLCA verified the bedrock depth by comparing information from HLA's field logs HLA's reports and PG&E's drawings (1978 investigations).
.The boring locations shown in the above-three sets of data matched reasonably well except for the location of hole no. 3.
The error, offset indicated as west rather than east, was attributed to a typing error on plate 1 of HLA's.
report.
E01 1094 documented this error and classified it as Class D, Devia-tion error. This error was corrected. This. comparison verified that the bed-rock depth used in HLA's soils report and subsequent work is appropriate. The NRC staff agrees with RLCA's conclusion.
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9 4.5.1.3.1.2 Properties of Backfill Material RLCA verified HLA's definition of backfill material properties as follows.
1.
RLCA independently calculated soil parameters using actual laboratory test data originally reported by HLA. The test results reported by HLA agreed with the values independently calculated by RLCA.
2.
For the backfill samples the soil classifications assigned by the geologist on the field logs were compared with the soil classifications assigned to the same samples by the soils laboratory technician. The field classifica-tion and laboratory classification were in general agreement. The classi-fication by the laboratory technician was again verified by RLCA on the basis of laboratory test results. This procedure verified the soil classi-fications given in HLA's soils report.
3.
The reported unconfined compressive strength and corresponding field blow count data for the test samples were compared with the strength and blow
-count values from published literature. The comparison verified that the strength of the backfill material mentioned in HLA's soil report was of the same order of magnitude as that published in the literature for soils of comparable blowcount resistance.
Based on the above comparisons RLCA concluded that HLA's definition of the pro-perties of the backfill material is acceptable.
The staff agrees with RLCA on the soils data but finds the scope of verification lacking because it did not define the stratigraphy and numerical values of the properties.of the backfill material. RLCA plans to revise ITR #13.
4 l
4.5.1.3.2 Bearina Capacity 4.5.2.3.2.1 Strenath of the Bedrock HLA inspected the foundation excavation for the intake structure in 1972 and their inspection memo describes the bedrock as moderately hard, moderately strong n
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tuff and shale with minor weathering. All the borings at the intake structure were drilled only to the top of the bedrock.
In the absence of any data on the bedrock at the intake structure, HLA used data from a 1968 investigation.
Two unconsolidated undrained shear strength (UU) tests were performed by HLA on samples of tuff recovered from borings drilled for the intake line.
Both of these tests were conducted at the same confining pressure and yielded compar-able results.
For the bedrock at the intake structure HLA assigned strength parameters of 3 ksf for cohesion and 30' for angle of internal friction.
By comparing information from HLA's field logs, HLA's report and PG&E drawings for the 1968 study RLCA verified rock data such as:
location of borings, grade elevation, bedrock depth and description of rock samples. Thed$tawascon-sistent, except that the location of borings No. 18 through 22 were.shown along the " Discharge line" in HLA report whereas they were actually along the " Intake line." To validate the HLA-assigned rock strength parameters for the intake _struc-ture, RLCA compared them with the strength parameters recommended by HLA for the bedrock at the turbine building and at the OWST (c = 4 ksf, 0 = 35*, see Figure '
No. 4 in ITR #39).
RLCA compared the compressive strength measured (15 ksf)-in tests with the compressive strength quoted (76 ksf) in the literature for tuff and stated that the strength values from HLA tests can be considered as a low-i bound value for the overall strength of the bedrock at-the intake structure.
RLCA concluded that the HLA-assigned strength parameters are reasonable and acceptable for the bedrock at the intake structure.
Although'the data base is minimal the staff is of the opinion that the assigned rock strength parameters at the intake structure are within the values generally quoted in the literature for similar rock and are reasonable and acceptable.
4.5.1.3.2.2 Bearina Capacity and Settlement HLA recommended an allowable bearing capacity of 33 ksf for the bedrock.
RLCA computed the ultimate bearing capacity of the bedrock by assigning several sets of possible strength parameters for the bedrock and demonstrated the conservatism l
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s in HLA's recommendation. They concluded that HLA's recommendation is conserva-tive and acceptable..
HLA did not estimate'the settlement of the intake structure.
RLCA assigned a Young's modulus (500 ksi) and Poisson's ratio (0.39) for the bedrock, both obtained from the geophysical tests performed for the OWST. RLCA estimated that a load of 33 ksf-uniform bearing pressure would result in 0.75 in. of settlement. Also, a differential load of 23 ksf will cause a 0.5 in, of differential settlement.
RLCA concluded that the HLA's recommendation of 33 ksf allowable bearing pressure for the bedrock under the intake structure is accept-able for rock strength and settlement considerations.
During the technical audit meeting at RLCA's office (Appendix 5), the staff was informed by RLCA representatives that the maximum static bearing pressure under the intake structure is 10.16 ksf and there is a local maximum bearing pressure of 26 ksf, under a pier.
Considering that the actual bearing pressures are low the staff concludes that bearing capacity and settlement are satisfactory for the intake structure. The staff also concurs with RLCA's conclusion on the bearing capacity recommendation by HLA.
4.5.1.3.3 Lateral Pressures The intake structure is backfilled along three sides and the fourth side (west side) is open to admit sea water to the intake pumps. The bottom of the mat foundation is approximately 49 ft below the grade along the three backfilled sides and 7 ft below grade along the open side. The soil backfill along three sides is approximately 36 ft high on top of the bedrock and the bottom of the foundation is embedded approximately 13 ft below the top of the bedrock. On the west side there is no soil backfill and the foundation is embedded 7 ft below the top of bedrock.
For the backfill material, HLA assigned strength parameters of 35' for angle of internal friction and zero for cohesion. HLA calculated the lateral earth and water pressures on the east wall due to both static and dynamic (Hosgri SSE) loading conditons. The structure is postulated to slide westerly and hence For lateral pressures on the east wall of the intake strcture were computed.
07/14/83 8
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I the. static loading condition, the lateral earth pressure was computed for the at-rest earth condition. For the dynamic loading condition, the lateral earth pressure increment was computed for the dynamic active soil condition using a simplified method recommended by Seed-Whitman (Reference 5).
This computed dynamic active earth pressure was multiplied by 3 to compensate for the sim-plified assumptions in the analyses. HLA also computed the lateral water pressure for both static and dynamic loading, conditions. HLA combined water and earth lateral pressures for both static and dynamic loading conditions to obtain the total lateral force on the wall.
RLCA verified HLA's work by independently calculating the lateral pressures on the intake structure wall. For the backfill material, RLCA assigned strength parameters of 45' for angle of internal friction and zero for cohesion. For the static loading condition, the lateral earth pressure was computed for the active earth condition. For the dynamic loading condition', the lateral earth pressure i
increment was computed using Mononobe-Okabe method as modified by Seed-Whitman (Reference 5).
RLCA assumed the dynamic active earth pressure increment had a distribution with depth similar to 'that used for braced excavations in order to obtain the lateral earth pressure on a rigid wall.
RLCA also computed the lateral water pressure for both static and dynamic loading conditions. Water and earth lateral pressures for both static and dynamic loading conditions were combined to obtain the total lateral force on the wall. The total lateral force computed by RLCA was within 10 percent of the lateral force computed by HLA.
RLCA therefore concluded that HLA's determination of the lateral pressures on the wall is acceptable to IDVP.
RLCA's report (ITR #39) does not present a justification for the simplified assumptions in the analyses, the sensitivity of the estimated lateral forces to those assumptions, and the conservatism in the analyses.
In the absence of this information the staff considers this ITR to be incomplete. The staff con-ducted a technical audit of the background materials referenced in ITR #39.
Appendix 5 to this section presents the staff's report on this audit meeting.
l Appendix 3 to this section presents. staff's evaluation of ITR #39.
Section 3.3 of Appendix 3 presents detailed comments by the staff on HLA's and RLCA's.esti-mation of lateral pressures. As a result of the above RLCA has. agreed to revise 07/14/83 9
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ITR #39 to address the staff concerns.
The staff will review the revised ITR and report their findings in a future report.
4.5.1.1.3.
Slidina Resistance Figure 3 and 4 of ITR #40 show the foundation configuration for the intake structure. The potential for westerly sliding of the intake structure was j
investigated by HLA. The sliding surface and sliding resistance factors along this surface were postulated by HLA. The resistance consists of the shear strength of the rock, the coefficient of friction between the concrete founda-tion and the rock, and the passive resistance of the rock at the western end of the structure. HLA used a shear strength value of 3 ksf for rock, an angle of friction of 30 degrees between the foundation and bedrock, and a passive resistance of twice the rock shear strength.
RLCA verified the postulated sliding surface and resistance factors used by HLA, and RLCA concluded that HLA's, recommendations are ecceptable.
The shear strength parameters used in the analysis,are, based on limited data, but the staff believes that they are reasonable and agrees with their use.
- RLCA, however did not evaluate the total lateral force, total resistance to sliding and the resulting of the factor-of safety against sliding. This information is vital in assessing the margin of safety against sliding and for this reason the staff considers ITR #40 to be incomplete. Appendix 4 to this section presents the staff's evaluation of ITR #40.
RLCA has agreed to revise ITR #40 to address the above concerns. The staff will review the revised ITR and report their findings in a future report.
4.5.1.4 Conclusions The NRC staff has reviewed the IDVP Final Report and ITRs #13, 16, 39 and 40 prepared by RLCA for IDVP of the DCNPP and conclude the following.
HLA did not enforce a QA program in their Hosgri qualification work for the DCNPP prior to June 1978. QA review by RFR resulted in E0Is of Class D, Deviation errors which have been rectified. These errors do 07/14/83 10 DIABLO CANYON SEC 4.5
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not have any significant bearing on the design and/or safety of the structures.
-~ The geotechnical data available for the GWST and intake structure is-minimal. The design strength parameters were assigned by HLA based on available test data and engineering judgment. Both RLCA, and the NRC Staff. concurs with the HLA on the reasonableness of the assigned strength i
parareters.
The staff agrees with RLCA's conclusion that HLA's work for the static loading condition of the Outdoor Water Storage Tanks is acceptable.
f RLCA is revising ITR's 13, 39 and 40, for the intake structure. The staff will report their evaluation in a future supplement.
References t
1.
Interim Technical Report, Diablo Canyon Unit 1, Independent Design Verification Program, Soils-Outdoor Water Storage Tanks, Revision 0, ITR #16, by Robert L. Cloud Associates, Inc., December 8, 1982.
2.
Interim Technical Report, Diablo Canyon Unit 1, Independent Design Verifi-cation P-ogram, Soils - intake Structure,~ Revision 0, ITR #13, by Robert L.
i Cloud As'ociates Inc., November 5, 1982.
s 3.
Interim Technical Report, Diablo Canyon, Unit 1, Independent Design Veri-fication Program, Soils-Intake Structure Bearing Capacity and Lateral Earth Pressure, Revision 0, ITR #39 by Robert L. Cloud Associates, Inc.,
February 25, 1983.
4.
Interim Technical Report, Diablo Canyon Unit 1, Independent Design Design Verification Program, Soils Report - Intake Struture Sliding Resistance, ITR #40, Revision 0, by Robert L. Cloud Associates Inc., March 9, 1983.
6 07/14/83 11 DIABLO CANYON SEC 4.5
5.
Seed, H. B. and Whitman, R.V., " Design of Earth Retaining Structures for Dynamic Loads," ASCE Speciality Conference on Lateral Stresses and Earth Retaining Structures, 1970.
6.
Final Report - Independent Design Verification Program, Diablo Canyon Nuclear Power Plant Unit 1, by Teledyne Engineering Services, May 31, 1983.
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APPENDIX 1 Report Evaluation by NRC Staff Report:
Interim Technical Report, Diablo Canyon Unit 1,. Independent Design Verification Program, Soils-Outdoor Water Storage Tanks, Revision 0, ITR #16, by, Robert L. Cloud Associates Inc., December 8, 1982
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REPORT EVALUATION BY NRC STAFF Interim Technical Report, Diablo Canyon Unit 1, Indep,endent Design Verification Program, Soils-Outdoor Water Storage Tanks,
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Revision 0, ITR No. 16 by Robert L. Cloud Associates, Inc.
December 8, 1982 3
1 INTRODUCTION E
isu Interim Technical Report Number 16 (ITR #16) was prepared by Robert L. Cloud k
Associated, Inc., (RLCA), for the Independent Design Verification Program (IDVP) of the Diablo Canyon Nuclear Power Plant (DCNPP). Teledyne Engineer-ing Services (TES), who is the program manager for this IDVP has issued this ITR (Reference 1).
The following evaluation of ITR #16 has been prepared by the. I the NRC staff and incorporates the review comments of HRC5consultantI, p
Brookhaven National Laboratory (BNL). The staff has not reviewed any of the referencesidentifiedknITR#16butha telephone discussions with Mr. E i
Dennison and Dr. R. McNeill of RLCA.
ITR #16 presents RCLA's review of the geotechnical input for the foundation design of the Outdoor Water Storage Tanks (OWSTs) as the DCNPP. The geotech-nical work for the OWSTs was performed by the firm of Harding Lawson Asso::iates (HLA), RLCA reviewed HLA's wogas part of t'.he IDVP review for the DCNPP.As a result of the IDVP review h..T errors and open item (EDI) reports, which identify items in need of review and resolution, were issued.
E01 1100 and E0I 1101 identified the discrepancy in the location of borings used in develop-ing the bedrock depth at the 0WST site. Appendix A of this evaluation report presents details of E0I 1100 and E0I 1101. RLCA's review and resolution of these EDIs are also presented in ITR #16.
I 2 SUM 4ARY OF REPORT Interim Technical Report No. 16 (Reference 1)
The OWSTs are situated on the east side of the auxiliary / fuel handling building and are approximately 40 ft in diameter and 50 ft high. T.he steel tanks were originally founded on a compacted fill placed over the bedrock. Following the 07/12/83 1-2 DIABLO CANYON SER APP 1
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"Hosgri" evaluation in 1977, the compacted fill under these tanks was replaced with concrete and the steel tanks were encased in concrete. The depth of embedment of these tanks range from 0 to 15 ft below the adjoining grade.
ITR #16 presents RCLA's tview of HLA's geotechnical work for the OWSTs and includes a review of lithology gdetermination of soil / rock profile and des-cription of bedrock), strength properties and allowable bearing capacity of the foundation bedrock.
2.1 Litholoay Definition The geotechnical investigations for the OWSTs were performed by HLA in 1973 and 1978 and consisted of borings, laboratory tests on recovered samples and geophysical tests in the borings.
RLCA's review of lithology required verifi-cation of information in HLA's reports on the bedrock depth (bedrock profile),
description of the bedrock and properties of the bedrock.
2.1.1 Verification of the Bedrock Depth RLCA har verified the location of the borings and the depth to the bedrock by comparing information on these parameters from the following sources.
HLA Field logs (2 borings) 1973 investigations HLA Report of 1973 investigation HLA Field logs (14 borings) 1978 investigations HLA Report of 1978 investigations IOVP drawings showing location of borings PG&E final excavation drawing I
RLCA's verification (Table 1 of ITR #16) showed that the location of two borings, boring no. 2 (1973 investigation) and boring no. 11 (1978 investigation),as shown in the reports, cid not agree with that in the field logs. These were addressed in E011101 and 1100 reports and have been resolved. The errors were due to an incorrect description of the structures used as references in, locating the borings.
RLCA has rectified this error and stated that the loca-tion of the borings as shown now ~in the HLA reports, field logs and IDVP draw-ings are consistent, correct and acceptable.
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2.1.2 Verification of Bedrock Description and Strength Parrneters j
l The description of the bedrock presented in the HLA's report was compared with:
(1) the description of the bedrock presented in HLA's field logs, and (2) reports
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by others on previous investigations (Blume studies 1968,1969) at this site.
RLCA concluded that the description of the bedrock as presented in the HLA's report is consistent with the description given in HLA's field logs and 81 cme i
reports.
RCLA reviewed the test data presented in HLA's reports and verified that the rock strength parameters defined by HLA are acceptable.
The cata reviewed were the results of two confined compression tests on samples of bedrock.
These data were from investigations performed in 1973 by HLA. Th e
< n. ' < n u s 4 - m 7. ; p7'---d 4-, a n g, " L^.. The test samples were y-moderately to deeply weathered sandstone and hence the strength parameters determined from these tests were considered by RLCA to represent the low-bound value of the strength parameters for the bedrock.
RLCA has plotted one 1
i
- testdata,IlongwiththestrengthenvelopefortheHLArecommendedstrength parameters, which are cohension (c) a. 4 ksf and angle of internal friction (9) = 35 degrees (Figure 9 of ITR #16). Thesetwomatchverywell.
The com-pressive strength measured in these tests are lower than the compressive strength generally quoted in the literature for sandstone and RLCA concluded thattheabovestrengthparametersareconservative,representstheloweI.
(
bound strength of the bedrock and are therefore acceptable.
RLCA also reviewed the data from geophysical surveys performed in the general I
vicinity of the 0WSTs and calculated both Poission's ratio and modulus of elasticity parameters for the. bedrock using the compressional and shear wave i
velocities measured in the geophys'ical survey (Table 3 of ITR #16). -Newever, IT M t64 However, ITR #16 does not present the value of the modulus of l
elasticity used by HLA in their design.
RLCA assigned 500 kst for the modu-lus of elasticity for the weathered sandstone. This is the lowest value com-l puted from the geophysical test data (Table G of ITR #16) and is also Tower i
than the values quoted in literature for sandstone.
RLCA concluded that the recommended value of the modulus of elasticity (500 ksi) is conservative for settlement estimates and a acceptable ve4we for the bedrock in the OWST area.
l 07/12/83 1-4 OIABLO CANYON SER APP 1 t
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-. - -_ _ - - -.- ~ - -
i 2.2 Bearing Capacity i
4 2.2.1 Bearing Capacity-Control _1ed by Shear Failure of the Foundatio t Material The CWSTs are founded on concrete pieced over the bedrock.
HLA recommended an allowable bearing pressure of 80$@ for the OWSTs.
RLCA evaluated the ultimate bearing capacity against shear fatture for a 40-foot diameter foundation, using strength parameters of C = 4 ksf and %= 35* for the weathered sandstone occur-i ing beneath t.he OWST. The embedment of the tank foundation was varied from 0 to 15 feet in the calculations. The factor of safety against a shear failure of the foundation caterial at an allowsble bearing pressure of O M ranged from 4.L'to 6.
RLCA concluded that tne 60 ksf allowable bearing pressure recomended by HLA for the OW5Ts is acceptable.
2.2.2 Bearirra Capacitv - Controlled bv Settlement PLCA calculated the settlesent for a 40-foot diametur circular base founded on tne weatJ ered sanottena to be 0.5 ir:. fer a betring pressure of 80.ksf.
The settM xt es-computed using Poisson'a ratic equal t 0.39 ard e dulus of e
elasticity equal to 500 ksi.
This modulus value is the lowest of the set of modubs values computed from the geophysical test data. Hence, P.LCA states 1
tr.atthe0.5in,sgttlementisaconservativeestimateandthattneactual settlensntmayb%essthan0.5in. ITR #16 does not present any estimate l
by HLA for the settlement of ChSTs. *ALCA coxluded that the magnitude of the r
computed settlement for an EO ksf bearing pressure is not critical arc thera-fore accepted HLA's tecourendation of 80 ksf allowable bearing pressure for the 0WS!s.
i 1
3 E1M).UATION BY NRC STAFF i
3.1 L,ithelor! Definition Tne.nethodology and the results of RCl# s independent verification of the lithology at the OWSTs are presented in Section 2.1 of this report. The t
information used for defining tho'lithclogy, location of borings and de;th
[
b 07/12/63 1-5 DIA3LO CANYDN SER APF 1
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to bedrock, was verif tad by comparing data from several scurces. RLCA identi-fied discrepancy (E01 1100 and E01 1101) in the locaticn of two borings and the error was rectified.
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The error in the location of boring 12 (Table 1 of ITR #16) is relatively large but the effect of this on the determination of the bedrock depth is insignificant.
The discrepancies in the location of borings and depth to the bedrock are minor and within the variations mersally ercountered in field explorations. The NRC staff agrees with RLCA's conclusion that HLA's definition of the depth to bedrock at OWSTs is acceptable.
4 The description of the bedrock presented in HLA's report was verified by com-paring it with the information prasented in HLA's fleid logs of the borings and test pits, and also with reports by others on previous investigations at this site. The strength properties of the bedrock were v'arified by reviewing s
the results of two confined compression tests performed en rock samples and the results of geop' ysical tests performed in the general vicinity of OW5T's.
i n
RLCA cor.cluded that r.he descrintion and properties of the bedrock as oefined by HLA is a:ceptable for the IOVP. The NRC staff, although in generaJ agree-2 ment with the RLCA conclusiens, offers the following comment.
i The shear strength parameters...:-u.... used by HLA in their analy-sis and now acceptoe by RLCA are based on only two confined compres-i sion tests.
Figure 9 of ITR #16 shows'the envelope of recommended strength parameters (C 'z 4.0 ksf and 8
- 3SP) and plot of the data from one of the two tests. The envelopt an the one test match very l
nell so RLCA concluded that the strength parneeters are acceptable.
I The second test data does not match well with the strength envelops.
Although the data base is minimal, the recommended strength parameters l
are of the same order of magnitude generally quoted in literature fcr unweathered rock.
t
}
3.2 Bearinc Capacitv i
3.2.1 Bearing Canscity Controlled by Shear Failure i
i t
l l
HLA recommended al allowable bearing pressure of 80 ksi for the CW$Ts. RLCA I
l calculated the ultimate bearing capacity of the weathered rock beneath the i
07/ 12/S3 1+ 6 OIABLO CANYCN SER APP 1
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OWSTs and estimated the factor of safety against shear failure of the founda-1 tian material to be between 4.5 and 6 for foundation embedment ranging from j
0 to 15 ft. The NRO staff plotted the data from two tests reported by RLCA and estimated a conservative set of strength parametersjwhich art cohension C '= 5.5 ksf and angle of internal friction 8 = 28 degrees.
Uting these lower values of strength parameters the staff estinated the factor of safety against sheer failure of the foundation material to be 2.5 and 3.7 for foundation tot m embedment of G and 15 ft respectively. The NRC staff concurs the RLCA's con-g clusion that HLA's design of the OWST foundations for bearing capacity against.
shear failure is acceptable for static conditions. Evaluation of stability for the dynamic condition was not a part of HLA's oriQinal work and hence was not reviewed by RLCA in this ITR.
It may be evaluated by RLCA under a different ITR number.
3.2.2 Bearing Capacity - Controlled by Settlement The settlement of the CWST foundation ustr.g an allowablia bearing pressure of
~
20 ksf was estimated by RLCA to be 0.5 inches.
RLCA computed the settlement using the geissonf s ratio equal to 0.39 and the modulus of elasticity equal to 500 ksi.
This 500 ksi modulus is the lowest value of the modulus computed from the geophysical tast data (Table 3 of ITR #16) and results in a conservative (higher) estimate of the settlement. The NRC staff offers the fcilowing com-ments on the above.
The magnitude of the modulus of elasticity is strain-dependent and the modulus computed from the geophysical test cata corres-ponds to a low-strain condition. The modulus to be used in the settlement calculations should be from high-strain test data, corresponding to the static condition, and is known to be smaller than the low-strain modulus. However, the 1cwest value from the insitu test is used by RLCA and the conserva-tism implied in using this value may cemoensate for the reduc-tion in modulus at higher strain.
07/12/83 1-7 OIABLO CANYON SER APP 1 e
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-o ITR #16 by RLCA does not present the magnitude of the settlement for dynamic conditions because the analysis for the dynamic con-
&o dition was not a part of HLA's work and hence outside the scope 7
of ITR #16. This may be addressed by RLCA in a different ITR.
E f.
The NRC staff concurs with RLCA's method of verifying the allow-A, abic static bearing capacity by the settlement criterion.
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e 4 CONCLUSIONS
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The NRC staff has reviewed ITR #16 prepared by RLCA and conclude:
}W 1.
HLA's determination of the depth of bedrock and description of the bedrock, f
at the Outdoor Water Storage Tanks of the DCNPP are acceptable.
W. e concur-g with the IDVP findings.
g 3
o 2.
RLCA's method of verifying the strength parameters by replotting.the lab'o-e
.c
~
- ratory test data and computing the modulus of elasticity from the geophy-sical test data is acceptable to the staff.
RLCA has concluded that HLA's j
V soils work for determining the bearing capacity on minimal test data. How-ever, there is enough conservatism in the ferai foundation design of the OWSTs that the staff concurs with RLCA's firidings on the bearing capacity for the static condition. The stability of OWSgs under dynamic conditions was not evaluated by HLA and hence is outside the scope of this ITR #16.
T*
13 h::: 5::r r:.i;u d 53 '".C.'
..J., J..'."..... w lis, we int.egraceu 10" :p:-t :h; d be chicked t: ::""" +"++": tai; hn hun L...wei in t.he T n530 7 eg r -
REFERENCE 1.
Interim Technical Report, Diablo Canyon Unit 1, Independent Design Verifica-tion progra, Soils - Outdoor Water Storage Tanks, Revision 0, ITR #16 by Robert L. Cloud Associates, Inc., December 8, 1982.
07/12/83 1-8 DIABLO CANYON SER APP 1
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E0I Reports Issued
. # 7'.'
b The IOVP issued nine E0I reports concerning HLA soils work. Only E0Is 1100 and y
1101 apply speci cally to the outdoor water storage tank soils review.
4 i l
EDI 1100 rep' orts a boring log for the HLA outdoor water storage tank work that.E 2 incorrectly notes two firewater tanks { firewater tank is located at the site.
The location of this boring was confirmed by comparison with the HLA report and by reference to the auxiliary building stairs.
Because this inconsistency was not a mistake in analysis, design or construction, EDI 1100 was resolved as a deviation.
E0I 1101 reports inconsistencies in the location of boring 2 for the HLA outdoor water storage tank work. The HLA field log indicates that the boring is in line with Unit 1 containment, while the HLA report shows that the boring is in line with Unit 2 containment.
Further discussion with the original field encineer noted this item as a mistake on the field log.
Because this inconsistency was not a mistake in analysis, design or construction, E0I 1101 was resolved as a deviation.
07/14/83 A-1 DIABLO CANYON SER APP A
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APPENDIX A EDI Status Soils Review E01 Action Physical i4 File No.
Subject Rev.
Date By Type Required Mod.
I !
J 1100 Outdoor Water 0
8/16/82 RLCA OIR RLCA Tanks - Boring #11 -
1 8/18/82-RLCA PPRR/DEV TES I
Additional Firewater Tank 2
9/10/82 TES PRR/DEV PGandE 3
11/11/82 TES CR None No j
i 1101 Outdoor Water Storage 0
8/16/82 RLCA OIR RLCA i
Tanks - Boring #2 -
1 8/18/82 RLCA PPRR/0IP TES Location 2
9/10/82 TES PPR/0IP PGand E 3
11/13/82 TES DIR RLCA I
4 11/18/82 RLCA PPRR/DEV TES I
5 12/3/82 TES PRR/DEV RLCA l
6 12/3/82 TES CR None No STATUS: Status is indicated by the type of classification of latest report received by PGandE:
l OIR - Open Item Report ER - Error Report A - Class A Error j
PPRR - Potential Program Resolution Report CR - Completion Report B - Class B Error PRR - Program Resolution Report CI - Closed Item C - Class C Error j
PER - Potential Error Report DEV - Deviation 0 - Class D Error j
OIP - Open Item with future action by PGandE PHYSICAL M00: PRysical modification required to resolve the issue. Blank entry indicates that modification has not been determined.
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