ML20085C594
| ML20085C594 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 08/11/1972 |
| From: | Watson J TENNESSEE VALLEY AUTHORITY |
| To: | Kreusi F US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8307110013 | |
| Download: ML20085C594 (2) | |
Text
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TENNESSEE VALLEY AUTHORITY
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CH ATTANOOGA TENNESSEE 374o1 l
August 11, 1972 Mr. Frank E. Kreusi, Director Directorate of Regulatory Operations United States Atomic Energy Commission Washington, DC 205h5
Dear Mr. Kreusi:
Westinghouse Electric Corporation has informed us that recent testing of ice baskets associated with the Westinghouse ice condenser containment design resulted in structural failure.
We do not consider this failure a design deficiency as defined by AEC regulations [10 CFR 50, 50.55 (c)] since the irregularity was discovered during a preinstallation test at the vendor's site, and the design is not finalized until the preinstallation tests have been satisfactorily completed. However, since our Sequoyah Nuclear Plant (Docket Nos. 50-327 and 50-328) utilizes the ice condenser containnent, we would like to make you aware of this matter.
From December 1966 through December 1968, functional steam blow-down tests were performed using baskets made from 12-1/2-gauge wire on 1-inch by 1-inch centers. These tests, reported in WCAP-7183 and supplements 1 and 2, demonstrated the structural and functional adequacy of this design.
Subsequent developments of the ice condenser resulted in the modification of the basket design to 1k-gauge wire on 1-inch by 2-inch centera. This change was justified, based on an analytical evaluation of the required strength where the vertical wires were subjected to column loading. However, the analytical evaluation did not adequately consider that eccentric and shear loads contribute to column instability.
Recently, preinstallation ice loading tests were performed at Westinghouse's Waltz Mill site to confirm the basket design.
During these tests, it was noted that after ice loading of a complete basket column (48 feet) the bcttom basket began to buckle and with melting of the bottom portions of the ice column (approximately 12 inches) the basket buckled. The baskets were manufactured in accordance with design specifications, and quality assurance was performed to assure specifications were met. There-fore, it is concluded that manufacturing deviations did not con-tribute to this failure.
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. Mr. Frank E. Kreusi August 11, 1972 To correct this inadequacy, all baskets will be replaced using the initial 12-1/2-gauge wire on 1-inch by 1-inch centers. As described previously, these baskets have been tested under actual blowdown conditions and, in addition, tests have been conducted where ice molting uns simulated while under equivalent horizontal and vertical earthquake londs.
An initial production run of new baskets will be retested to ecnfirm the structural adequacy.
Very truly yours, TENNMISEE VALLEY AUTHORITY it.m ;.1 6
- h1 Jame[hE. Watson ManSger of Power
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CC:
Mr. Jchn G. Davis, Director k /
Directorate of Regulatory Operations United States Atomic Energy Commission Hegion II - Suite 818 230 Penchtree Street, NW.
Atlanta, Georgia 30303 I
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