ML20054M722

Summary of 820622 Meeting W/Util & S&W Re Recent Findings on Geological Faults Discovered in Discharge Tunnel Excavation Area

ML20054M722
Person / Time
Site:	Millstone
Issue date:	06/30/1982
From:	Jeffery Grant Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 8207140302
Download: ML20054M722 (6)

Text

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jt)H 3 01932 Docket No.: 50-423 APPLICANT: Northeast Utilities FACILITY: Millstone, Unit No. 3

SUMMARY

OF MEETING HELD TO DISCUSS GE0 LOGICAL FAULT FINDINGS i

i Enclosed is a summary of the meeting held on June 22, 1982, to discuss the recent findings on the geological faults discovered in the discharge tunnel excavation area of the Millstone-3 site. NRC staff members, R. Jackson, J. Grant and J. Mattia met with representatives from Northeast Nuclear Energy Company and Stone & Webester Engineering Company.

The enclosed report also includes rect.mnendations to the applicant in preparing a detailed report onthe fault findings. A draft of this report should be submitted by September 1, 1982. Following the staff's review, we recommend further that the applicant make any necessary changes or additions, and submit thefinal report by October 1,1982. This report should also be referenced in the FSAR to be tendered in November 1982.

. Sincerely, J. M. Grant, Project Manager

- Licensing Branch No. 1 l

Division of Licensing l

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Mr. W. G. Counsil .

Senior Vice President "

Nuclear Engineering and Operations -

Northeast Nuclear Energy Company Post Office Box 270 Hartford, Connecticut 06101 cc: Mr. Harve L. Plasse, Manager R. W. Bishop , Esq.

City of Chicopee Electric Corporate Secretary Light Department .

Northeast Utilities 725 Front Street Post Office Box 270r -

Chicopee, Massachusetts 01014 Hartford, Connecticut 06101 Mr. Guy W. Nichols,' President Mr. Richard T. Laudenat, Manager New England Electric System Generation Facilities Licensing 20 Turnpike.Rd. Northeast Utilties Service Company '

Westborough, Massachasetts '01581 Post Office Box 270 --

Hartford, Connecticut 06101 Mr. Bruce R. Garlick .

Manager, Energy Supply Mr. J. C. Mattia "

Fitchburg Gas and Electric Resident NRC Inspector Light Company Office of Inspection and Enforcement 655 Main Street U. S. Nuclear Regulatory Commisision Fitchburg, Massachusetts 01420 Post Office Box 128 Waterford, Connecticut 06385 -

Mr. D. Pierre G. Cameron, Jr.

General Counsel Mr. E. R. Foster, Director Public Service Company of Generation Construction New Hampshire Northeast Utilities Service' Company 1000 Elm Street Post Office Box 270 Post Office Box 330 Hartford, Connecticut 06101 Manchester, New Hampshire 03105 Mr. Bruce McKinnon

. Gerald Garfield, Esq. Power Contracting Manager Day, Barry & Howard Massachusetts Municipal Wholesale One Constitution Plaza Electric Company Hartford, Connecticut 06103 Post Office Box 426 "'

Ludlow, Massachusetts 01056

. John D. Fassett, Chairman &

) Chief Executive Officer Mr. Bruce H. Grier

. The United Illuminating Company. U. S. NRC, Region I S0 Temple Street 631 Park Avenue New Haven, Connecticut 06506 King of Prussia, Pennsylvania 19406 Mr. R. O. Bigelow, Vice President New England Power Company 20 Turnpike Road Westborough, Massachusetts 01581

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MEMORANDUM FOR: Jane Grant, Licensing Project Manager Licensing Branch No. _

FROM: Robert E. Jackson, Chief Geosciences Branch, DE

SUBJECT:

INPUT TO TRIP REPORT - MILLSTONE 3 - FAULT STUDY -

On June 22, 1982 we visited the Millstone 3 site to examine geological investigations of faults discovered in the excavations for the discharge tunnel as initially discussed in the June 4, 1982 memorandum of . . .

R. Jackson to J. Knight which is attached.

We have received two preliminary reports from the appiicant and their consultants, Stone and Webster Engineering Co. reporti-ng on these faults -

dated June 4, 1982 and June 15, 1982. These reports also include maps and photo documentation and were provided to allow for staff preparation for a field visit.

The field visit consisted of an initial briefing by the applicant and consultants followed by an examination of the discharge tunnel excavation floor and north and south walls. The floor of the excavation was visible in areas which had not been covered by concrete. Excellent photographic coverage of those areas which had been covered was provided to us. Our examination covered the area from grid E 500, N1300 to the area of the 2nd (most easterly) duct bank crossing (approximately E680, N1180). We examined fault areas F-2781, and F-2817, 2818, and 2819 in both the north and south walls. In addition, two other fault-like features were also noted in the ar'ea of duct bank No. I crossing and also the duct bank No. 2 crossing at the east end of the excavation walls which were available for inspection.

After our field visit, we informed the applicant of the following l

observations.

E-2781, North Wall There is a contect between the bedrock surface and the glacial till/out-wash material. This contact shows compaction drag of this glacial material against the bedrock surface. The projection of the fault does l not project to this contact but further to the west. Further excavation of material over the projection of the fault while we were at the site l indicated the presence of a continuous clay-like till layer over the fault. The applicant was informed that they should excavate, map and photograph a zone about 10-20 feet wide from the top to the bottom of the excavation wall in the area of F-2781. This work should include both the glacial and bedrock material with special emphasis on the areas

~TTault o projection into the glacial material.

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JUN 2 8 1982 .

F-2781, South Wall In this excavation we observed a cobbly till layer overlying the fault and r.ot displaced by it. This till unit is difficult to trace unequivo-cally and further work in higher stratigraphic units should be under-taken. Further scrapping, detailed mapping and photography in both the glacial and bedrock material is heeded to confirm the obsemation of the -

lack of offset of the cobbly till unit. This should include, at a minimum, a zone 20 feet wide from the floor to the top of the excavation. <

F-2817-19 North Wall Where the fault projects to the surface in this area, it is difficult to trace because the bedrock is highly weathered. The till-bedrock relationships in this area are, therefore., difficult to demonstrate.

The applicant was requested to clean and map an area 10-20 feet wide in -

this area making the best attempt possible.

F-2817-19, South Wall We observed traceable continuous glacial stratigraphic units overlying the faults in this area in close proximity to the bedrock-glacial material contact. Tyse units did have a synclinal nature to them in this area which matfched the general bedrock surface contour. The applicant was required to map, and photograph in detail, an area 20 feet

- wide from the bottom to the top of the excavation. This mapping.should include attention to both the glacial and bedrock material. In this general area, higher in the section of the glacial material, some small normal faults were observed. These faults had several inches of offset and were discontinuous, i.e. did not project.any significant distance into layers above or below.

Duct Bank Crossing No. 1 This area has not been mapped by the applicant. We observed a contact of about 15 feet been a glaciated bedrock surface and varved outwash l material. This feature gives the appearance of an apparent fault due to l the contact. Above this contact are continuous unbroken outwash units.

l The bedrock beneath this outwash area is too deep for excavation. The l

applicant is to map and photograph this area.

Duct Bank Crossing No. 2 In this area, we briefly observed a small graben-type feature which has not yet been evaluated. It appears to be a ice wedge structure related to melting of an ice block. The applicant is to report further on this feature.

M28 199g Overall Observations The applicant should provide a detailed report on this excavation including thorough documentation of the walls of the excavation.

. Careful attention should be placed on mapping the glacial material. In the area of special features, detailed sections should be prepared demonstrating the bedrock-glacial material relationship. The applicant -

indicated that it would take several months to prepare this report. We -

suggested that a draft report be submitted by September 1, 1982 and later referenced in the FSAR.

Based upon all observations, the faults in the bedrock are similar in nature to those previously observed at the site and are not capable. No - - -

offsets in the glacial material were observed to be related to the bedrock faults and those that are present can be explained by glacial processes such as ice block melting and compaction. A further review will be issued if necessary upon receipt and review of- the applicant's -

report in September.

d . , FC Robert E. Jac' q( Chief Geosciences ranch Division o E ineering

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B. Youngblood S. Brocoum L. Reiter H. Lefevre D. McMullen j

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JUS'di 1982 ,

MEMORAt:DUM FOR: James P. Knight, Assistant Director for Components & Structures Engineering, DE FROM: Robert E. Jackson, Chief Geosciences Bra'nch, DE -- - - -

SUBJECT:

DISCOVERY OF FAULTS Ill DISCHARGE TUtillEL EXCAVATION MILLST0flE 3 Two iaults hahe been encountered in the. excavation for the discharge --

tunnel. One of these faults has.been mapped by the applicant and appears to.be similar to other faults which have been-discovered in other excavations on the site. Studies supplied.by the applicant on these previously-discovered zones.were reviewed by the staff and ' '

indicated that they were not capable in accordance with Appendix A to 10 CFR 100.

The applicant is currently mapping and photographing the second. fault and will supply photos and documentation to us.as soon as possible.

Based on our. previous experience with these faults, H. Lefevre gave verbal approval to allow placement of " mud mat" concrete over the mapped fault in order not to unnecessarily interfer with ongoing construction schedules.

The' applicant has further indicated, however, that.some displacement (small faults).have been discovered in the glacial material at.the site. We have ,

not previously been aware of such features on this site. Based on our'past experience, these displacements are probably.due to differential compaction of, material or melting (during past glaciation) of ice blocks which had been covered by sediments. This is .a comon phenomena in glacial terrain. We. .

have requested that the applicant excavate.to bedrock (about 20 f.eet deep) '

to observe whether there is bedrock offset.

WepresentlyplantomakeafieldYisitonJune 22, 1982 to observe these features in order to minimize any impact on construction activities 'at the site.

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Robert E. a kson, Chief Geoscien ' ranch Divisio Engineering cc: R. Vollmer .Lefehre T. Sullivan R. McMullen S. Brocoum J. Grout L. Reiter Co .. e o Avuoy,jT/

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MEETING

SUMMARY

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] Document-Control; (50-423)

NRC PDR M 3 0 22 L PDR TERA c NSIC LB#1 Rdg.

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I Project Manager .m n ,., n , .

Attorney, OELD OIE ,

Regional Administrator, Region 1 4

PARTICIPANTS (NRC): - -

R. Jackson - ~

J. Matti'a R. Busch ~

A. Gulesserian I

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