ML20090B321

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Testimony of Hn Singh Re Svc Water Pump Structure
ML20090B321
Person / Time
Site: Midland
Issue date: 11/16/1981
From: Singh H
ARMY, DEPT. OF, CORPS OF ENGINEERS
To:
Shared Package
ML17198A223 List: ... further results
References
CON-BOX-13, FOIA-84-96 OL, OM, NUDOCS 8202050095
Download: ML20090B321 (4)
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  • Y UNITED STATES OF AMERICA NUCLEAR REGULATORY CChMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the metter of

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Docket Nos. 5 0-329HE&oL Consumers Pogr Company

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.iO-330-0M&OL (Midland Plan, Units 1 and 2)

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A TESTIMONY W HARI RRAIN SINGE ColCERNING

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SERVICE WATER PUMP STRUCTURE

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Q-1.

Elease state your name ud position with the U.S. Army Corps of Engineers.

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My name is Rari N. Singh.

I sa a Civil Engineer in the Geotechnical

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Branch of the Engineering Division, NCD in Chicago, Illinois, U.S. Army Corps of Engineers.

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Q-2.

How did the U.S. Army Corps of Engineers get involved in the review process of the Midland Plant, and what are the areas of its responsibilities.

A.

Rarsuant to an interagency agressent between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Army Corps of Engineers (the Corps) which became effective in September 1979, the Corps undertook to provide technical assistance to the NRC. 1he Corps provides assistance on the geotechnical engineering aspects of the Midland Plant.

  • Q-3.

Have you prepared a statement of your professional qualifications?

A.

Yes, a copy is attached.

Q-4.

Please state the nature of your responsibilities with respect to the Midland Plant.

A.

My involvement with the Midland Plant began in May 1980, when I was assigned the responsibility as the Corp's lead rariswer for the geotechnical concerns at the Midland Plant as lead reviewer, I worked with engineers and geologists of the Geotechnical Engineering Section of the De troit District, who were engaged in reviewing the materials used in the foundation design' of the plant.

As the full-time lead reviewer, my responsibilities were to '

coordinate with all the reviewers, examine their comments, perform my own review, discuss comments with the Section Chief and prepara a final letter i

report to be transmitted to the NRC. The structures being reviewed include the followirs:

1) Auxiliary Building; 2) Reactor Building Units 1 and 2;
3) Diesel Generator Building; 4) Borated Water Storage Tanks thics 1 and 2;-
5) Service Water Pump Structure; 6) Diesel Puel Storage Tadts; 7) Seimmic Category I Piping and Conduits; 8) Retaining Walln; and, 9) the dikes adjaceae.

i ta the Emergency Cooling Water Reservoir (ECWR).

- Q-5.

What are the existing soil problems-at the Sereice Water Pun' ~ Strueturet p

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A.- The Service Water Pump Structure is located in the southeast corner of the power block area adjacent to the Cooling Pond.

The structure is rectangular in shape with overall dimensions of 106'x 8 6'.

The structure is built on two levels with the main part founded on natural material at elevation 587.00, and the small northern partion founded on compacted fill materials, at elevation 616.00.

Figures 18 'and 19 of Attachment-1 show the plan and a typical section af the structure.

The northern portion is cantilevered off the main portion.

j, Subsequent to the excessi e settlements of the compacted fill under the Diesel Generator Building, borings were taken in all the ceapacted fill under

' Category I structures. Such borings taken in the compacted fill under the Service Water Structure had revealed that fill unterials consist of sof t to very stiff clay and loose to very dense sand (50.55(e) report of 10 August 1979). Based on these borings, it uma concluded that some fill material areas of the northern portion of the Service Water Structure were not sufficiently i

coapacted.

As a consequence of poor compaction, the foundation soils do not provide adequate support to the portion of the Service Water Pump Structure foundation i

on fill materials.

The existing dead load of the northern part is being i

partially carried by the main structure through cantilever action. This change in structural behavior of the northern portion of the structure introduced additional bending and shear stresses in the structure causing cracks on the cross walls (See Figures 23, 24, & 25 of Attachment-1).

Further, unless the poor fill materials are corrected, its reactive support to the structure would continue to diminish increasing the cantilever action, i

jeopardizing the safety of the structure.

Since the -fill supported structure is not designed to act as cantilever from the main structure, its safety is i

l being threatened by continued reduction in foundation support.

Q-6.

What was the originally proposed remedial measures?

A.

To stabilize the fill supported portion of the Service Water Pump Structure (to elin.inate cantilever action), the applicant originally planned to support the northern wall of the structure with 16-13" diameter concrete filled steel piles with 100 tons capacity each.

Figures 20, 21, and 2 2 of shove the plan view of the piles as well as the method of

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transferring vertical loads from the well to the piles by a system of reinforced concrete corbels. The piles were to be driven in to the natural soil through pre-drilled holes in the campacted fill anterials.

This proposal l

was furnished to the NRC through S0.55(e) report (Interim report 6 da~ted l

11 June 1979).

The Corps of Engineers reviewed the proposal, but because of insufficient j

information it could not evaluate the adequacy of the proposal.

In its letter report of 7 July 1980 (Attachment-2), the Corps of Engineers requested the information required for the. review.

A brief description of the information required is as follows:

(a) Analysis for capacity of the piles against vertical as well as

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lateral loads.

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a (b) Engineering properties of the natural soils s well as compacted fill

- materials through which the piles were to be driven.

l (c) An analysis for the negative skin friction on piles which were inevitable due to future settlement of the fill materials.

j (d) Total actual load to be transmitted to the' ground through the piles.

(e) Analysis for possible settlement that could occur between the pile 4

supported and and the portion of the structure placed on natural material.

(f) Dynamic analysis af the 100 tons capacity piles.

1 The applicant's response to.these requests was not satisfactory.

De Corps of Engineers report of 15 April 1981 (Attachment-3) provides the details.

Q-7.

What is the currently proposed remedial naasures?

A.

During the NRC structural audit in March 1981, the applicant gave an indication that it had revised its proposed remedial measures for the Service Water Pump Structure.

Preliminary drawings for the new proposal were displayed during the audit, one in the first week of May 1981 and another on 17 September 1981, the applicant provided the following details:

The current remedial naasures consists of providing a continuous 4' vide 1

concrete underpinning wall undar the outer walls of the fill supported portion of the Service Water Pump Structure.

The foundation wall will be carried down 4

from the underside of the existing foundation slab through the fill materials to the natural. soil. Bus, the structure loads will be carried by the i;

foundation walls to the natural soil without stressing the problem fill materials.

He walls will be 30' high with a belled bottom of 6' width to distributetheloadonIlargerarea. The walls will be constructed in small sections from tunnels which will be advanced simultaneously from access shafts located at northeast and northwest corners of the building.

Q-8.

Did Corps of Engineers review the currently proposed remedial measures, if so what were the results?

i A.

He informa*. ion pertaining to the new remedial action firnished by the applicant in the May and September meetings at BethesdI, MD,.and also j

transmitted of ficially to the Corps of Engineers were reviewed. W e review

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comments are provided in the minutes of the 17 September meeting prepared by H.N. Singh of the Corps of Engineers, North Central Division, Chicago, Illinois (Attachment 4). A sumanry of the review comments are as follows:

(a) Bearing Capacity:

Bearing capacity analysis and the corresponding -

shear strength parameters were neither-discussed daring t.he asetings nor provided in the applicant's submission of 2 6 August 1981, therefore, the.

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adequacy of the foundation soil in shear failure cculd not be evaluated.

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(b) Since the imiderpinning un12s will be built in sequence of' sections (See Attachment 5) and the initially built sections would be required to 3

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_1 support the weight of the overhang when the tunnels are advanced considerable distances frca the access shafts, it is probable that sections (piers) 1 & 3 on either end of the north well will be highly overloaded.

This concern was exprev +-8 by the Corps and the NRC staff during the meeting of 17 September 1981 ac dethesda.

The applicant has not demonstrated by analysis that foundation soil under these piers are safe against shear failure under the maximum probable load during the construction period.

(c), According to page 5, section 7 of the applicant's submission of 2 6 August 1981, it appears that the static structural analysis has not been completed. However, at the September usating at Bethesda, when the applicant 3

. presented the preliminary details of its new proposal, it was stated by the applicant's consultant (Bechtel Corporation) that the structure has been analysed for static load representive soi* media under the underpinning wall with springs of appropriate stiffness.

The details of the spring constants l

were not presented. Therefore, the Corps of Engineers has not been able to f

review the details of soil stiffness used in the analysis.

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(d) The dynamic spring constants were reported to be evaJusted on the basis of the " Elastic",porps has not been able to evaluate the dynamic Half Space Theory", but detailed analysgTs were not l-furnished. 'therefo re j

stiffness of the soils.

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Conclusions.

Corps of Engineers has not evaluated the adequacy of the soils that are going to support the underpinning wells, because of the j

following information are still needed to complete the reviews

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(a) Report on soil exploration and testings performed by the Woodward-Clyde Consultants for the borings in the area of the Service Water i

Pump Structure.

l (b) Bearing capaci 7 analysis.and the resulting factor of safety for the

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soils, under the underpinning wells, using the results of the tests preformed j

by Woodward-Clyde Consultants on samples taken from Boring 00E-16.

(c) Bearing capacity analysis and factor of safety for the soils under

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the piers (piers located at northeast and southeast corners of the structure) j that are subject to higher loa'ds during normal plant operation period.

(d) Soil spring constants evaluation for static and dynamic load.

l (e) ' An analysis showing that the soils under the main portion of the i

structure is adequate to support the additional loIds likely to be brought j

upon them during construction period through building post-tensioning.

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