IR 05000329/1978012

IE Inspec Repts 50-329/78-12 & 50-330/78-12 on 781024-27 During Which No Items of Noncompliance Were Noted.Major Areas Inspected incl:10CFR50.55(e) Rept Concerning Settlement of Diesel Generator Foundation & Bldg

ML20062F569
Person / Time
Site:	Midland
Issue date:	11/14/1978
From:	Gallagher E, Spessard R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
Shared Package
ML20062F568	List: IR 05000329/1978012 ML20062F565
References
50-329-78-12, 50-330-78-12, NUDOCS 7812190160
Download: ML20062F569 (11)

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U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT

REGION III

Report No. 50-329/78-12; 50-330/78-12 Docket No. 50-329; 50-330 License No. CPPR-81; CPPR-82 Licensee: Consumers Power Company 1945 West Parnall Road Jackson, MI 49201 Facility Name: Midland Nuclear Power Plant, Units 1 and 2 Inspection At: Midland Site, Midland, MI Inspection Conducted: October 24-27, 1978

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Inspector: [g.J.Ga E

SMr agher I/&h'p

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Approved By:

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R. L. Spdssard, Chief y Il y ( *r,.

C Engineering Support Section 1 Inspection Summary I_nspection on October 24-27, 1978 (Report No. 50-329/78-12; 50-330/78-12)

Areas Inspected: 10 CFR 50.55(e) report concerning settlement of diesel generator foundation and bui.1 ding; backfill specifications and quality control instructions; preliminary soils test results from core boring investigation; site implementing procedures; performance of soils testing; and diesel generator building and pedestal details. The inspection involved a total of 36 inspector-hours onsite by one NRC inspecto Results: No items of noncompliance or deviations were identifie (' .

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DETAILS

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Persons Contacted Principal Licensee Employees (Consumers Power Company)

• T. C. Cooke, Project Superintendent

• L. Corley, Station Head IE and TV

• E. Horn, Civil Supervisor, QAE

• M. Wheeler, Civil Engineer

• H. Peck, Construction Supervisor

• Bauman, Project Engineer

• S. Keeley, Project Manager

• B. Miller, Site Manager Bechtel Associates Professional Corporation

• L. A. Dreisbach, PQAE

• R. L. Castleberry, Project Engineer

• L. Barclay, PFQCE

- *P. A. Martinez, Project Manager ( *A. Boos, Project Field Engineer J. Betts, Field Engineer A. Marshall, Geotechnical Engineer S. Blue, Geotechnical Engineer J. Wazeck, Geotechnical Engineer N. Swanberg, Chief Engineers Staff B. McConnel, Civil Design Group P. K. Chen, Civil Design Group T. Lieb, Quality Control Engineer U.S. Testing Laboratory ,

J. Speltz, Lab Supervisor NRC Resident Inspector ( *R. Cook, Inspector

• Denotes those present at exit meetin Functional or Program Areas Inspected Followup of Reportable Occurrence (10 CFR 50.55(e)) - Settlement of Diesel Generator Foundations and Building In accordance with the requirements of 10 CFR 50.55(e), Consumers Power Company notified the NRC Region III office of a reportable-2-I' l

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occrrrence relative to the settlement of the diesel generator foundations and building.

, Deficiency The Bechtel Foundation Data Survey Program (spec. C-76) generated data that indf eated the settlement of the diesel generator foundations was greater than anticipated. Nonconformance Report No. 1482 was generated on August 21, 1978 to document the occur- '

renc Due to the magnitude of the settlements observed, a soils boring program was initiate Safety Implications Large settlements can pose aafety problems for the buildin These structures are monitored for settlement during construc-tion and operation as part of the foundation data survey program.

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Unusual settlements of the structure would be detected before the diesel generators would be rendered inoperable due to

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resulting distortion ; Activities in Progress i (1) Foundation Data Survey Program has been expanded to include additional data locations and to increase the frequency of monitoring these locations to a weekly basis rather than the previous 60 day basi (2) A Boring program has been initiated to provide better definition of the compacted fill conditions supporting

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the diesel generator building as well as other plant structures, e.g., Class 1 tanks, transformer foundations and plant fill area. Soil samples have been recovered

for laboratory tests. Details of these tests are provided

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in later sections of this repor ' Planned Activities for Future Work Discussions with licensee representatives indicate the fol-lowing planned activities for future work relative to diesel l generator building foundations end other plant structures:

(1) Extend bench mark monitors for settlement stud ,

, (2) Install inclinometers

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(3) Preload diesel generator building and foundations; both inside and around the building with 20 to 22 feet of sand for approximately 5 to 7 month (4) Build retaining wall to separate preload material from turbine building on the north sid (5) Check calculation to see if turbine building can carry effect of preload surcharg (6) Monitor condensate lines under diesel generator buildin (7) Monitor soil movement during preloa (8) Provide freeze protection around diesel generator area during winte (9) Monitor concrete cracks using stain gauge (10) Monitor pore water pressure in soil.

(' (11) Cut loose the four electrical duck banks which run under

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the building and project vertically becoming an integral part of the structur (12) Continue filling pond from elevation 622' to 627'.

(13) Identify item ef fected by the structure, i.e. plant saf ety, -

operations and layou e. Other Activities to be Planned (1) Possible core borings in cooling pond dike area to verify integrity of dike (2) Continue visual inspection of dikes for movemen f. Other Structures Being Monitored for Settlement (1) Borated water storage tank foundations (2) C.W. intake structure '

(3) Emergency diesel fuel oil tank (4) Service water valve pits (5) Chlorination building .'

(6) Radwaste building (7) Cooling towers

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. Review of Preliminary Data Compiled through Soil Borings in Diesel Generator Building Area A review of the preliminary report data compiled by Goldberg, Zoino, Dunnicliff and Associates, consultants in geotechnical engineering was performed. This investigative soils work is being performed in accordance with the specification for technical services for soils testing, C 79(Q), Rev. O, issued September 8, 1978. Tests are performed in accordance with applicable quality assurance require-ments included in the specification, in particular, test c atrol, control of measuring equipment, handling and storaSe of materials and document contro A total of 23 core borings to various elevations into and through

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the compacted fill and into natural soil in and around the diesel generator building have been pertormed. In addition, dutch cone probes were taken to determine the bearing capacity of the in-place soils. Soil samples were recovered from the borings in order to perform a battery of soil tests which include: soils classifi-cation, mechanical anelysis, atterberg limits, natural moisture contents, unit weights, compaction, unconfined compressive strength, unconsolidated-undrained triaxial compression tests, consolidation C tests and organic content determinatio Preliminary results of the investigative soils borings work indi-cate the fill under the diesel generator building has variable strength properties. For example: Unconfined compressive strength tests range from 163 PSF (boring DC 2, sample 5) to $230 PSF (boring DG 1) with the majority of results less than 2000 PSF.

, Blow counts through the fill range from 3 to 6 blows per foot (DG 2) to 2 to 40 blows per foot (DG 12), and as much as 100 blows per foot in some area Dutch cone probes to determine bearing capacities indicate

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less than 5 kips per square foot (KST) in probe Nos. 1, 2, ( 4, 8, 10, 5 KSF is the design bearing capacity based on discussion with the Bechtel design staf Penetrometer tests were performed in test pit No.1 between elevations 628' and 616' in the east bay of the diesel '

generator building. Results indicate an unconfined compressive '

strength average of 1.0 ton per square foot (TSF) with a range f rom 0 to 4.5 TS .

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The final evaluation of the soils borings in the diesel generator area is expected to be presented to Consuners Power Company during the week of November 6, 1978. This information is planned to be presented to the NRC some time thereafte . Review of FSAR Commitments Versus Site Implementing Procedures The inspector found the following discrepancies between commitments in the FSAR and the requirements in applicable site implementing specifications, procedures and drawings: FSAR Table 2.5-14 (Summary of Foundations Supporting Seismic Category I and 11 Structures) identifies the supporting soil material under the diesel generator building as being, " con- (

trolled compacted . cohesive soils." In addition, FSAR Table 2.5-9 (Minimum Compaction Criteriah identifies soil type and i function. Under " support of structures" the soil type is ,

identified as clay which is a cohesive soi However, construction detail drawings C-109 R2 and C-117 R6 identify the material in this area as " zone 2" material. Zone

/: 2 material is identified in FSAR Table 2.5-10 as " Random Fill,"

described as any material free of organic or other deleterious material. In the field a variety of material has been used for the diesel generator building, e.g. sands, clay, silty sand, clayey sa.nd and lean concrete. A review of the records indicate sands have been used between elevations 594' to 608', ,

areas of elevation 611' to 613' and areas between 616' and 628'.

Lean concrete was permitted to be used indiscriminate 1y through-ou This indicates the extent of the variability of the material used under the diesel generator building foundatio FSAR Table 2.5-21 (Summary of Compaction Requirements) iden-tifies " random fill" to require a compaction effort of a

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minimum of 4 passes with specified equipment. This requirement <

of 4 passes was not an imposed criteria in Bechtel specifi-cation C-210 R6 nor was it an inspection requirement of Bechtel *

Quality Control Instruction for Backfill, C-1.0 In addition.

{ FSAR section 2.5.4.5.3 (fill) states, "the four passes were required for each substitute roller."

Discussion with QC field personnel indicated that documentary evidence was not available to determine that the required number of passes were performed. However, it was commented that at times more than 4 passes were required in order to attain the minimum compactio .

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,: FSAR Section 3.8.5.5 states, that ('. settlements of shallow spread footings founded on compacted fill are estimated to be on the order of 1/2 inch or less.", The site survey program has ider-tified settlements in'.he diesel generstor foundation and

~ building to range f ros '0. 55 inches' to .2.30 inches and in excess of 3.0 inches for the' diesel generator'redestal, as of September 197 . / ' <

n FSAR Figure 2.5-47 indicates the fout.dation of'the diesel, generator building is at elevation 634'; however, designj drawing C-1001(Q) R$ indicates the . spread footing and pedestal are at elevation 628' and locally lowered to'clevarfon 625'

in the sump areas. Since the ground water elevation will be raised to 627', a hydrosiatic pressure will re' duce the net effective structure load on the foundation material. This should be reflected in ' table accompanying FSAR figure 2.5-4 ' Review of Specifications for Site Soils Activities The inspector reviewed the fo'11owing procedores and specifications for installation and testing of site soil materials:

' Bechtel Specification C-210, Revision-6, dated April 25, 1978, Sections 12 and 13 Plant Area Backfil Requirements.

. Eechtel Specification C-211, Revision 4 dated September 21,

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1977, Structural Backfil . Bechtel' QC Instruction for Compacted Backfill, C-1.02, Revision An apparent conflict was identified during review of the specifi-cations. Specification C-210, Section 13.7.1 requires all cohesive backfill in the plant area to be compacted to not less than 95%

maximum density, as determined by ASTM D-1557, Method D which requires an effective compactive effort of 56,000 ft-lbs of energy per cubic foot of soil. However, Section 13.4 (testing) of the specification requires testing of materials placed in the plant area to be per-

'r forled in accordance with tests listed in Section 12.4. This scetion~, in particular Section 12.4.5.1 (cohesive soils), requires lab 2aximum densities to be determined using ASTM D-1557, Method D provided a compactive energy equal to 20,000 foot pounds per cubic foot is applied (Bechtel Modified Proctor Density). To date, the Bechtel modified proctor density for determining maximum proctor density versus optimum moisture content has been utilized, as com-mitted to in FSAR Table 2.5-9. Furthermore, Bechtel Quality Control Instruction C . 02, Section 2.4 (testing) references the-7-

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applicable inspection criteria, including both Sections 13.7 and 1 of specification C-210 which includes the discrepancy described abov ,

As a result of this conflict..the actual in-place compaction would be less using the Bechtel modified proctor than using the standard ASTM D-1557, Method This is due to the fact that the compactive energy exerted using the Bechtel modified method is less than that using the standard ASTM method (i.e. 20,000 ft-lbs versus 56,000 ft-lbs of energy).

, During a revicw of the specifications, the inspector was informed l

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that Bechtel had contracted Dames and Moore to perform the origina site soils and backfill study, as documented in a-report dated March 15, 1969. On page 16 of this report the compaction criteria for support of structures is recommended to be 100% of the maximum density using a compactive effort of 20,000 ft-lbs (similar to Bechtel Modified Proctor Density). However, this 100% of maximum density using 20,000 ft-lbs of compactive effort corresponds to 95% compaction using the standard ASTM D-1557, Method As pre-viously described, specification C-210 did not incorporate the

.. Dames and Moore recommendatio ,

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Furthermore, Dames and Moore report (page 15) states that, "all fill

> and backfill materials should be placed at or near optimum moisture

' content in nearly horizontal lifts approximately 6 to 8 inches in loose thickness." This recommendation was not adopted by Becthel, 4 in that specification C-210, Section 12.5.3 permits an uncompacted <

lift thickness of 12 inche l A further review of specification C-210, Section 12.6 (moisture control) indicates that zone 2 material, known as " random fill",

was permitted to have a moisture content tolerance of "not more ;

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than 2 percentage points below optimum moisture and not more than 2 percentage points above optimum moisture." A review of the moisture-density curves for the material (random fill) placed in i the diesel generator area indicates steep, sloped moisture-density ,

curves, and therefore, a + 2% range for moisture control can j significantly effect the in-place density of the material use {

Review of NRC Question No. 362.2 on FSAR Section 2.5.4. This question concerns whether a natural sand layer near elevation 5 600', as identified in FSAR Figure 2.5-21, had been removed during I construction or if the sand tested out to be greater than 75%

relative density. The licensee had not responded to this question -

as of the date of this inspectio t

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An internal Consumers Power Company memorandum from B. H. Peck to J. L. Corley indicates that a review of records had not yielded any verification that the sands were removed or that tests were performed to confirm the in-place density of the natural sand The current boring program will also be used as a data base for confirming the in-place condition of the natural sand layer iden-tified in FSAR Section 2.5.4.5.1. The licensee informed the inspector that the results of this survey will provide the basis for their answer to NRC Question No. 36 . Cracks in Concrete Structural Wall and Footing in the Diesel Generator Building The inspector observed the structural concrete crack that has developed in the east exterior wall and footing of the diesel generator building. The crack was observed by representatives of Bechtel Geotech and Consumers Power Company.

j As of September 22, 1978, the settlement along the east side of the building, as measured by the survey data program, ranges from 0.55" to 2.48", a differential settlement of 1.93 inches. The crack is

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(" expected to have been induced due to flexure caused by the differ-ential settlement. Discussions with Bechtel design staff per.onnel at the site indicate that the crack is being evaluated along with the settlement survey and will continue to be monitored during preload of the structur *

ACI 318-71 (Commentary) Section 10.6.4 limits flexural cracks to 0.013 inches (13 mils) when exposed to the outside elements. The crack was observed to be larger than the ACI limit for flexcr The licensee is committed to this standard in FSAR Section 3.8. . Observation of Soil Testing in Compacted Fill Areas The inspector observed U.S. Testing Lab personnel performing the following soil tests:

- Lab Test ASTM D-1557-66T, Moisture-Density Relations of Soils, I

Method D, which determines the moisture-density relation by compacting cohesive soil in a standard sold in 5 layers with a 10 pound weight dropping 18 inches, 56 times in each laye The density per cubic foot is calculated for given moisture conditions. This information yields a curve which indicates the maximum lab density (proctor density) at an optimum moisture content. This value is then compared to the in-place field dry density to yield the percent (%) compactio .

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. Field Test ASTM D-1556-64, Density of Soils In-place by Sand Cone Method, which determines the in-place field dry density for the soil which is compared to the maximum lab density ,

determined as described above in paragraph (a) (proctor density), to yield the 2 compactio The above tests were observed to be performed in accordance with the applicable test standard Diesel Generator Building and Pedestal Foundation Details The diesel generator building is founded on approximately 35 feet of compacted fill with its foundation support provided by a 10 foot wide, 2'-6" thick spread footing supporting the structure abov The footing and walls are' cast-in-place reinforced concrete. The diesel generator pedestal is independent of the surrounding structure and consists of a 6'-6" thick mass reinforced concrete pedestal to support and distribute the load of the diesel generato Passing underneath the diesel generator building in the north-south -l direction are two condensate water lines (non-safety related) and )

. a series of four electrical duct banks (safety-related) that run j under the building and project vertically becoming an integral part l of the structure in each of the four diesel generator bays. Bechtel design staff personnel indicated that the condensate linee and duck -

banks have influenced the differential settlement in local areas of the structur I

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Of significance is that the original ground water level prior to l plant construction was approximately at elevation 601'. Subsequent l

to construction of the cooling water pond, the ground water table

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has risen to elevation 622', and it is planned to be raised to its maximum elevation of 627'. This increased ground water level has stabilized in the compacted fill beneath the diesel generator building at elevation 622'. The licensee is evaluatinF the effects of this increase in ground water level on the 35 feet of compacted fill material in the plant fill are Exit Interview (

The inspector met with site staff representatives (denoted in Persons L Contacted) at the conclusion of the inspection on October 27, 1978.

l The inspector summarized the purpose and findings of the inspectio .

The licensee acknowledged the findings reported herei In summary, the licensee has reported the deficiency and had initiated an extensive soils testing investigation of the foundation material The final results of these terts are scheduled to be complete by

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November 6, 1978 and are to be presented to the NRC staff shortly there-after. The deficiency reported in the 50.55(e) report will be reviewed after the proposed resolution to.the settlement of the plant structures has been established. Additionally, this matter has been referred to l IE Headquarters for evaluation.

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