ML20129D822

Forwards Request for Addl Info Re Erosion of Cement from Underlying Porous Concrete Drainage Sys,At Plant Unit 3

ML20129D822
Person / Time
Site:	Millstone
Issue date:	10/18/1996
From:	Rooney V NRC (Affiliation Not Assigned)
To:	Feigenbaum T, Harpster T NORTHEAST UTILITIES SERVICE CO.
References
TAC-M96402, NUDOCS 9610250157
Download: ML20129D822 (5)

Text

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

Mr. Ted C. Feig:nbaum October 18, 1996

, Executive Vice President and

, Chief Nuclear Officer

Northeast Utilities Service Company 1 c/o Mr. Terry Harpster

Director - Nuclear Licensing Services P.O. Box 128 i  !

Waterford, CT 06385  !

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION ON EROSION OF CEMENT FROM THE UNDERLYING POROUS CONCRETE DRAINAGE SYSTEM, MILLSTONE UNIT 3 l (TAC NO. M96402)

Dear Mr. Feigenbaum:

In reviewing your letters dated July 12, August 1, and August 9,1996, we find that we need additional information. We plan to meet with you October 31, 1996, at the Millstone Nuclear Power Station to discuss the status of the Millstone 3 concrete erosion testing program, and to gather information relative to the basemat erosion issue. Would you please plan to discuss in that meeting as much as possible of the information requested in the enclosure l i

I to this letter. Please also provide a written response providing the requested information within 30 days of the date of the meeting.

Sincerely, j Original signed by: l Vernon L. Rooney, Senior Project Manager Northeast Utilities Project Directorate Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket No. 50-423

Enclosure:

Request for Additional Information cc w/ encl: See next page DISTRIBUTION:

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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 Harpster 4

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

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION ON EROSION OF CEMENT FROM THE I UNDERLYING POROUS CONCRETE DRAINAGE SYSTEM, MILLSTONE UNIT 3 (TAC NO. M96402)

Dear Mr. Feigenbaum:

1 In reviewing your letters dated July 12, August 1, and August 9,1996, we find that we need additional information. We plan to meet with you October 31, 1996, at the Millstone Nuclear Power Station to discuss the status i

of the Millstone 3 concrete erosion testing program, and to gather information i

relative to the basemat erosion issue. Would you please plan to discuss in that meeting as much as possible of the information requested in the enclosure t i

to this letter. Please also provide a written response providing the l 7 requested information within 30 days of the date of the meeting. I l

Sincerely,

/ k( W Vernon L. Rooney, Senior Project Manager i Northeast Utilities Project Directorate  !

Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket No. 50-423 1

Enclosure:

Request for Additional Information cc w/ encl: See next page J

1 RE0 VEST FOR ADDITIONAL INFORMATION l

EROSION OF CEMENT FROM THE POROUS CONCRETE DRAINAGE SYSTEM i MILLSTONE NUCLEAR POWER STATION. UNIT 3 JJ_C N0. M96402

References:

1. Letter B15803 (with Attachments) from Northeast Utilities (NU) to NRC, Dated July 12, 1996.

2. Letter B15825 (with Attachments) from NU to NRC, Dated August 1, 1996.

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3. Letter B15850 (with Attachments) from NU to NRC, Dated  !

August 9, 1996. l (1) Provide a complete ;escription and findings from Phase I, Phase II, and Phase III (to the extent available) mock-up testing.

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(2) Reference 3 describes the Phase III mock-up test as related to the study of interaction between the calcium aluminate concrete, and the portland cement concrete of the basemat. Provide the information regarding the relative deterioration of the two concretes by comparing the 60-day strengths of (1) portland cement mold before and after the test, and (2) that for the high alumina cement concrete. Comparisons with the specified strengths (as shown in the Conclusion) is inappropriate.

(3) The Phase III mock-up test also indicated that there was a complete lack of bond between the portland cement concrete mold (representing the basemat concrete), and the calcium aluminate concrete of the test mold. i Provide information regarding the consequences of the lack of bond on the i load transfer to the foundation, and on the dynamic behavior of the i structure. l i

(4) UFSAP. Section 3.8.1.6.1 states, "In general, concrete mixes were of a 28-day strength of 3,000 psi unless otherwise specified by the Engineer."

However, in response to question I.1 (Ref.1), the strength of the containmat basemat concrete is indicated as 3,000 psi at 60-days.

Provide information on what was really used. If available, provide  ;

information regarding the strength of lab-cured and field-cured cylinders i taken from the basemat concrete during construction. This information is useful in comparing the degradation effects, if any, with the results of the mock-up tests.

(5) Provide a relationship between the grain size distribution of the sump slurry (Attachment 3, Ref.1), and the finer particles and cement l particulates in the porous concretes layers. This information is useful in understanding and predicting the ability of the erosion process to continue.

Enclosure

(6) An Operability Determination (00) has been provided in Attachment 2 to Reference 2. In item F.la, a gross assumption has been made that the full 800 feet of drainage pipes are filled with eroded cement. Figure II.2-3

attached to Reference 1 shows the daily count of the total amount of water

collected in the sumps in the year 1994. The peak flow shown is about 6,700 gallons of water per day. Such a large flow is not feasible if the pipes were even half filled with the hardened cement. There is a vast uncertainty in estimating the yearly accumulation of dry weight of the cement residue. Based on the results of the mock-up tests and other information (e.g., the latest estimate of 1996 cement residue), provide one reasonable scenario in your OD that can be compared against the future accumulation of cement slurry in the sumps.

(7) Four additional hypothetical scenarios have been postulated in the 00 (Attachment II, Ref. 2). In the evaluation of each scenario, a statement is made at the end of the evaluation, "The containme .c mat has sufficient rigidity to span over these hypothetical gaps without any impact on the mat qualification." The results of the calculations, if any, have not been provided. Provide the results of the calculations (stresses and deflection) for the fourth scenario (where a 5-foot diameter gap has been assumed) considering the gap to be under the heavily loaded area, for example, under the fully loaded crane wall, or reactor (primary shield) wall.

(8) Erosion of cement from the porous concrete layers is continuing, and it is necessary to monitor the movement of the foundation basemat under heavily loaded areas of the basemat (e.g., crane wall and primary shield wall).

Provide information regarding your plans for monitoring the settlements under sucn areas.

(9) The effects of uniform and diffentential settlements could be monitored by inspecting the surface conditions of the walls near discontinuities, and 1 pipe alignments around piping penetrations in the containment wall, crane l wall, and the primary shield wall. Provide your plans to implement I augmented inspections for this purpose, l l

l m ._

Northeast Utilities Service Company Millstone Nuclear Power Station Unit 3 4

cc:

Lillian M. Cuoco, Esq. M. H. Brothers, Nuclear Unit Director Senior Nuclear Counsel Millstone Unit No. 3 Northeast Vulities Service Company Northeast Nuclear Energy Company P.O. Box 270 P.O. Box 128 Hartford, CT 06141-0270 Waterford, CT 06385 Mr. Kevin T. A. McCarthy, Director Burlington Electric Department

, Monitoring and Radiation Division c/o Robert E. Fletcher, Esq.

Department of Environmental Protection 271 South Union Street 79 Elm Street Burlington, VT 05402 Hartford, CT 06106-5127 Mr. M. R. Scully, Executive Director Mr. Allan Johanson, Assistant Director Connecticut Municipal Electric Office of Policy and Management Energy Cooperative Policy Development and Planning Division 30 Stott Avenue 80 Washington Street Norwich, CT 06360 Hartford, CT 06106 Mr. William D. Meinert Mr. S. E. Scace, Vice President Nuclear Engineer Nuclear Reengineering Implementation Massachusetts Municipal Wholesale  !

Northeast Utilities Service Company Electric Company l P.O. Box 128 P.O. Box 426 Waterford, CT 06385 Ludlow, MA 01056  !

Regional Administrator Mr. E. A. DeBarba Region I Vice President - Nuclear ~ Technical U.S. Nuclear Regulatory Commission Services 475 Allendale Road Northeast Utilities Service Company King of Prussia, PA 19406 P.O. Box 128 Waterford, CT 06385 First Selectmen Town of Waterford Joseph R. Egan, Esq.

Hall of Records Egan & Associates, P.C.

200 Boston Post Road 2300 N Street, NW i Waterford, CT 06385 Washington, D.C. 20037 l

Mr. P. D. Swetland, Resident Inspector Millstone Nuclear Power Station c/o U.S. Nuclear Regulatory Commission P.O. Box 513 Niantic, CT 06357 Mr. D. B. Miller, Jr.

Senior Vice President Nuclear Safety and Oversight Northeast Utilities Service Company P.O. Box 270 Hartford, CT 06141-0270

d Northeast Utilities Service Company Millstone Nuclear Power Station Unit 3 cc:

Mr. F. C. Rothen Vice President - Nuclear Work Services Northeast Utilities Service Company P.O. Box 128 Waterford, CT 06385 Mr. Ernest C. Hadley, Esq.

1040 B Main Street P.O. Box 549 West Wareham, MA 02576 Mr. John Buckingham Department of Public Utility Control Electric Unit 10 Liberty Square New Britain, CT 06051 Mr. James S. Robinson Manager, Nuclear Investments and Administration New England Power Company 25 Research Drive Westborough, MA 01582 Mr. B. D. Kenyon President - Nuclear Group Northeast Utilities Service Company P. O. Box 128 Waterford, CT 06385