IR 05000312/1972003
| ML19309A237 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 08/31/1972 |
| From: | Albert W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| Shared Package | |
| ML19309A228 | List: |
| References | |
| 50-312-72-03, 50-312-72-3, NUDOCS 8003260936 | |
| Download: ML19309A237 (2) | |
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UNITED STATES
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' c ATOMIC ENERGY COMMISSION DIRECTOR ATE OF REGULATORY OPER ATIONS
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REGION V
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2111 B ANCROFT WAY h
BERKELEY. CALIFORNI A 94704
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174g August 31, 1972 RO Inquiry Report No. 050-0312/72-03/CDR Subject: Sacramento Municipal Utility District (Rancho Seco)
Sacramento County, California Construction Pamit No. CPPR-56 963 Mwe PWR, B&N Prepared by:
W. G. Albert, Reactor Inspector Date A.
Date and Manner AEC was Informed Mr. Leon Beratan RO:HQ, phoned G. S. Spencer RO:V, on August 28, 1972 to inform him that the Directorats of Licensing had received information that the ends of tendon strands were slipping out of their wedges at Rancho Seco. Additional information was obtained in a series of phone calls between Mr. V. McMahon of SMUD and W. G. Albert, RO:V, on August 28 and between W. Friedricks and G. Drew of SMUD and W. G. Albert on August 30, 1972.
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Description of Construction Deficiency Sixteen of the horizontal tendons installed in the Rancho Seco containment vessel were short because of the circular pitch assumed by the tendon when drawn through the spiral tendon sheaths. Due to the shortness of these tendons, one end was installed with a normal amount of excess length and tensioned by normal methods, the other end was left short and tensioned about three months later by a short stroke
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" front end loading" Jack. This jack was designed to measure lift-off readings during in-service inspection and was therefore capable of attachment to short tendon strands.
On 8/12/72, when the front end loading jack became available, the
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tensioning of the short ends of the 16 short horizontal tendons was started. In one of these tendons, fH-50, 9 of the 55 strands had slipped in their wedges. Four of the 9 strands had slipped sufficiently that they could no longer be gripped by the wedges. Examination of the other 15 short tendons did not show any slippage of strands.
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RO Inquiry Rpt No 050-0312/72-03/CDR-2-August 31, 1972 C.
Action by Licensee calculations have been performed on the ability of the remaining 46 strands of tendon H-50 to assume the ter 5ioning load. These showed that 98% of the design load will be taken by this tendon if it is stressed to the initial loadirt intended for tendons in this position,
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rather than the relaxed loading which would have been applied to a couplete tendon by virtue of the 3 match delay in tensioning. This tensioning has been completed.
An investigation of the cause of slippage is underway. All data and investigation results will be incorporated in the nonconforming report of the licensee.
In addition, the licensee plans a partis 1 inspection of tendon ends
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prior to conducting the initial containm:nt leak test. This will include a 1007 inspection of all strands in the 16 short tendons.
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