ML20215M644

Forwards Summaries Re Current Status of Basemat Issue & Significance of Analyses as Presented in Oct 1986 Confirmatory Analyses Rept.Existing Physical Evidence Shows That Cracks Tight & Not Changing

ML20215M644
Person / Time
Site:	Waterford
Issue date:	05/06/1987
From:	Murley T Office of Nuclear Reactor Regulation
To:	Stello V NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO)
Shared Package
ML20215M198	List: ML20215M196 ML20215M644 ML20215M663
References
NUDOCS 8705140072
Download: ML20215M644 (2)

Text

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May 6, 1987 Docket No. 50-382 MEMORANDUM FOR: Victor Stello, Jr.

Executive Director for Operations FROM: Thomas E. Murley, Director Office of Nuclear Reactor Regulation

SUBJECT:

CURRENT STATUS OF BASEMAT ISSUE AT WATERFORD 3 1

l At the time of the full power licensing of Waterford 3 in March 1985, a condi-tion was placed in the Waterford operating license which required that LP&L submit the results of analyses that were to be conducted to confirm the licens-ing basis for th^ plant. The final report of these confirmatory analyses was submitted for staff review in October 1986. The staff review of these analyses determined that the report is not clear and that the document advanced a characterization of the basemat that is not consistent with the staff's prior understanding of the stress conditions in the basemat. Previously, the staff's understanding of the basemat was that the cracks developed during the construc-tion sequence due to differential settlement, im)osition of dead loads and normal thermal and/or shrinkage effects. Once t1e basemat was loaded with structures and components this was thought to result in compression in the top l of the basemat. Onlysmallareasofthetopofthebasematneartheperimeter walls were thought to be under slight tensile loads. Results of calculations presented in the final report indicate that large areas of the basemat are l under significant tensile stress. This information is not consistent with the l confirmatory mapping.

The licensee and staff have had several discussions of the significance of the analyses as presented in the report and LP&L is actively involved in addressing both problems described above. Enclosures 1, 2 and 3 contain summaries of these discussions.

Although the licensee is in the process of extending its analyses to address the staff concerns, there are several factors which lead the staff to conclude that there is no immediate safety issue. Existing physical evidence indicates that the cracks are tight now and the surveillance prorram currently in place provides assurance that the cracks have not changed anc are not changing. If the cracks really were under significant tensile stress, one would expect the cracks to be open and that they would continue to grow over time.

1. 3/

Thom1s Murley Director OfficeofNucIcarReactorRegulation As stated CONTACT:

J. Wilson /NRR, PD - IV 0700140072 070006 pon AnacK 05000302 49-29403 P PD" DISTRIBUTION

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Docket No. 50-382 Victor Stello, Jr.

MEMORANDUM FOR:

Executive Director for Operations FROM: Thomas E. Murley, Director Office of Nuclear Reactor Regulation

SUBJECT:

CURRENT STATUS OF BASEMAT ISSUE AT WATERFORD 3 At the time of the full power licensing of Waterford 3 in March 1985, a condi-tion was placed in the Waterford operating license which required that LP&L submit the results of analyses that were to be conducted to confirm the licens-

ing basis for the plant. The final report of these confirmatory analyses was submitted for staff review. The staff review of these analyses determined

! that the report is not clear and that the document advanced a characterization I of the basemat that is not consistent with the staff's prior understanding of l the stress conditions in the basemat. Previously, the staff's understanding of the basemat was that the cracks developed during the construction sequence due to differential settlement, imposition of dead loads and normal thermal and/or shrinkage effects. Once the basemat was loaded with structures and components, this was thought to result in compression in the top of the basemat. Only small areas of the top of the basemat near the perimeter walls were thought be under slight tensile loads. Results of confirmatory analyses presented in the l final report show that large areas of the basemat are under significant tensile stress.

The licensee and staff have had several discussions of the significance of the analyses as presented in the report and LP&L is actively involved in addressing

! both problems described above. Enclosures 1, 2 and 3 contain summaries of these discussions.

l Although the licensee is in the process of extending its analyses to address the staff concerns, there are several factors which lead the staff to conclude that there is no immediate safrty issue. Existing physical evidence indicates

that the cracks are tight now and the surveillance program currently in place provides assurance that the cracks have not changed and are not changing. If the cracks really were under significant tensile stress, one would expect the cracks to be open and that they would continue to grow over time.

Thomas Murley Director l Office of Nuclear Reactor Regulation  ;

Enclosures:

i As stated l CONTACT:

J. Wilson /NRR, PD - IV 49-29403 DISTRIBUTION Uocket tile NRC PDR Local PDR i PD4 Reading Division Director 0GC i l E. Jordan B. Grimes J. Partlow 1 l J. Wilson P. Noonan ACRS(10) l J

PD Plant File T l R4/LA PD4/$ 5 PD4/D/ F DR4A D0 )) D Al l )Noonan JWilsohiM JCalvo FSch'r or DCre@tchfield F / glia 1 4/3/87 4/45/fp 4/a/87 4 4/87 4/#f87 /

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