ML20129C353

Forwards RAI Re Porous Concrete sub-foundation.Response Requested within 14 Days

ML20129C353
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	10/18/1996
From:	Stephen Dembek NRC (Affiliation Not Assigned)
To:	Feigenbaum T, Harster T NORTHEAST UTILITIES SERVICE CO.
References
NUDOCS 9610240001
Download: ML20129C353 (4)

Text

.

Mr. Ted C. Feigsnbaum October 18, 1996 Executive Vice President and l Chief Nuclear Officer Northeast Utilities Service Company

. c/o Mr. Terry L. Harpster .

, Director - Nuclear Licensing Services P.O. Box 128 Waterford, CT 06385

SUBJECT:

REQUEST FOR INFORMATION CONCERNING POROUS CONCRETE SUB-FOUNDATION i

Dear Mr. Feigenbaum:

1 4 l The NRC has been evaluating the reported erosion of cement from under the containment foundation basemat of Millstone Unit 3. The Millstone Unit 3 I

containment foundation basemat is supported on rock; however, between the rock surface and the underside of the structural concrete basemat there are several layers of material, one of which is a 9-inch thick porous concrete layer consisting of coarse stone aggregates and high alumina cement. Six inch diameter porous concrete pipes are installed in this porous concrete layer to collect and drain ground water which may seep down along the periphery of the containment wall. The collected water drains into two sumps inside the Engineered Safety Features building. Cement slurry has been observed in these sumps. Based on our review of the information provided to us so far, there is no immediate safety concern because the amount of cement estimated to have possibly eroded since the plant was built in 1975 is only a small fraction of the total cement weight of the porous concrete, and because no adverse consequences of the cement erosion are either predicted or have been observed i at Millstone Unit 3. With regards to any generic implication of this issue on I other containment foundations with similar design, the staff has identified additional plants for which it requires more detailed information, including the Haddam Neck Plant.

Enclosed is a request for additional information. Please provide your i response within 14 days from receipt of this letter. j i

Sincerely, l l

Original signed by:

Stephen Dembek, Project Manager Northeast Utilities Project Directorate Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket No. 50-213 Distribution Docket File

Enclosure:

As stated PUBLIC PDI-3 P1 ant I/

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'% + October 18, 1996 Mr. Ted C. Feigenbaum Executive Vice President and Chief Nuclear Officer Northeast Utilities Service Company c/o Mr. Terry L. Harpster Director - Nuclear Licensing Services P.O. Box 128 Waterford, CT 06385

SUBJECT:

REQUEST FOR INFORMATION CONCERNING POROUS CONCRETE SUB-FOUNDATION

Dear Mr. Feigenbaum:

The NRC has been evaluating the reported erosion of cement from under the containment fcundation basemat of Millstone Unit 3. The Millstone Unit 3 containment foundation basemat is supported on rock; however, between the rock surface and the underside of the structural concrete basemat there e several layers of material, one of which is a 9-inch thick porous concrete layer consisting of coarse stone aggregates and high alumina cement. Six inch diameter porous concrete pipes are installed in this porous concrete layer to collect and drain ground water which may seep down along the periphery of the containment wall. The collected water drains into two sumps inside the Engineered Safety Features building. Cement slurry has been observed in these sumps. Based on our review of the information provided to us so far, there is no immediate safety concern because the amount of cement estimated to have possibly eroded since the plant was built in 1975 is only a small fraction of the total cement weight of the porous concrete, and because no adverse consequences of the cement erosion are either predicted or have been observed at Millstone Unit 3. With regards to any generic implication of this issue on other containment foundations with similar design, the staff has identified additional plants for which it requires more detailed information, including the Haddam Neck Plant.

Enclosed is a request for additional information. Please provide your response within 14 days from receipt of this letter.

Sinc ely, te hen Dembek, Project Manager Northeast Utilities Project Directorate Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket No. 50-213

Enclosure:

As stated cc w/ enclosure: See r. ext page s

_ . - ._ _ _ . _ _ . _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ . _ - . _ _ _ _ . = . . _ . _ _ __.

• O

{

2 .- T. Feigenbaum Haddam Neck Plant j' Northeast Utilities Service Company J

cc:

1 l Lillian M. Cuoco, Esq. Mr. S. E. Scace, Vice President Senior Nuclear Counsel Nuclear Reengineering Implementation

Northeast Utilities Service Company Northeast Utilities Service Company l P.O. Box 270 P.O. Box 128

Hartford, CT 06141-0270 Waterford, CT 06385

, Mr. Kevin T. A. McCarthy, Director Regional Administrator

Monitoring and Radiation Division Region I i Department of Environmental Protection U.S. Nuclear Regulatory Commission 2

79 Elm Street 475 Allendale Road i Hartford, CT 06106-5127 King of Prussia, PA 19406  !

Mr. Allan Johanson, Assistant Director Board of Selectmen 2

Office of Policy and Management Town Office Building Policy Development and Planning Division Haddam, CT 06438

80 Washington Street l

! Hartford, CT 06106 Resident Inspector 1 i Haddam Neck Plant 1 j Mr. J. J. LaPlatney c/o U.S. Nuclear Regulatory Commission I

Haddam Neck Unit Director 361 Injun Hollow Road

} Connecticut Yankee Atomic Power Company East Hampton, CT 06424-3099

362 Injun Hollow Road East Hampton, CT 06424-3099 Mr. A. M. Callendrello Licensing Manager - Haddam Neck Mr. D. B. Miller, Jr. North Atlantic Energy Service Corp.

Senior Vice President P.O. Box 300 Nuclear Safety and Oversight Seabrook, NH 03874 i Northeast Utilities Service Company P.O. Box 270 Mr. James S. Robinson Hartford, CT 06141-0270 Manager, Nuclear Investments and Administration Mr. E. A. DeBarba New England Power Company Vice President - Nuclear Technical Services 25 Research Drive Northeast UH11 ties Service Campany Westborough, MA 01582 ,

P.O. Box 128 l Waterford, CT 06385 Mr. B. D. Kenyon President - Nuclear Group Mr. F. C. Rothen Northeast Utilities Service Company Vice President - Nuclear Work Services P. O. Box 128 Northeast Utilities Service Company Waterford, CT 06385 P.O. Box 128 Waterford, CT 06385

U RE0 VEST FOR INFORMATION CEMENT EROSION UNDER CONTAINMENT FOUNDATION Your plant (s) appear (s) to have a porous concrete layer below the containment basemat.

1. Have you found slurry in the drainage from this layer?

2. Has there been any settlement of the containment basemat?

3. Have you noticed any unusual conditions which may be related to the porous concrete sub-foundation layer?

4. Are you monitoring anything related to the drainage from the porous concrete sub-foundation layer (s) below the containment basemat?

5. Is calcium aluminate (high alumina) cement used as a constituent in the porous concrete mix?

l Enclosure