ML20040C581
| ML20040C581 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 01/07/1982 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| REF-PT21-81 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8201290043 | |
| Download: ML20040C581 (2) | |
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TE NESSEE VALLEY AUTHORITY
,ky AYTAf OOGA TENNESSEE 37401
I 400 Chestnut Street Tower II g 4.1 ggd January 7, 1982 BLRD-50-438/81-49 g%'d D
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,TC GPjgD g.j 2_719821~ ~h Mr. James P. O'Reilly, Director 9'
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission 3
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Region II - Suite 3100 c.
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101 Marietta Street Atlanta, Georgia 30303 4
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Dear Mr. O'Reilly:
BELLEFONTE NUCLEAR PLANT UNIT 1 - LOCK 0FF PRESSURE ON POSTTENSIONING SYSTEM - BLRD-50-438/81 FOURTH INTERIM REPORT The subject deficiency was initially reported to NRC-0IE Inspector R. V. Crlenjak on July 17, 1981 in accordance with 10 CFR 50.55(e) as NCR BLN CEB 8104. This was followed by our interim reports dated August 17, September 18, and November 17, 1981. Enclosed is our fourth interim report. We expect to submit our next report by April 1,1982. We consider 10 CFR Part 21 applicable to this deficiency.
If you have any questions concerning this matter, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY h
L. M. Mills, Mar ager Nuclear Regulation and Safety Enclosure cc:
Mr. Richard C. DeYoung, Director (Enclosure)
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 O1WICIAL COPY 8201290043 820107 PDR ADOCK 05000438 S
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ENCLOSURE BELLEFONTE NUCLEAR PLANT UNIT 1 LOCK 0FF PRESSURE ON POSTTENSIONING SYSTEM BLRD-50-438/81-49 10 CFR 50.55(e)
FOURTH INTERIM REPORT Description of Deficiency Inryco, Incorporated, Bedford Park, Illinois, has been contracted (contract 75C53-85380) to supply and install the posttensioning system for the primary containment structures. Allowable lockoff stresses for each tendon have been established by Inryco in accordance with the I
April 1973 Trial Use Version or the ACI 359 code and the contract specifications. These lockoff stresses are required to provide assurance that the containment structure will have adequate prestress i
force to perform its intended safety function.
In order to resolve a problem with certain stressing gauges being out of calibration, Inryco performed liftoff tests on several horizontal tendons. These lif toff tests revealed that, in several cases, lockoff stresses were substantially lower than predicted.
Interim Progress TVA has reviewed the sample lif toff data and concludeL that the scope of the low liftoff problem is limited to tendons fabricated with wire supplied by Florida Wire and Cable Company (FWC), Sanderson, Florida.
Bellefonte has been supplied with 113 of these tendons. Each of these tendons was used in the unit 1 horizontal prestress. Therefore, all unit 2 tendons and the unit 1 vertical and dome tendons are unaffected by this deficiency.
The FWC tendons are suspected to be undergoing excessive losses because of steel relaxation. The wire was specified and supplied as 8-1/2 percent relaxation wire.
It is suspected to have a higher percent relaxation than specified. TVA has reevaluated the prestress losses because of creep and shrinkage and determined that the specified values are overly conservative. This, coupled with the fact that the FWC tendons were initially locked off at greater than 70 percent of their Guaranteed Ultimate Tensile Strength, would support TVA's acceptance of wire somewhat in excess of 8-1/2 percent relaxation. Inryco and TVA are conducting 1000-hour relaxation tests on samples of FWC wire to verify the stress relaxation characteristics. These tests are anticipated to be complete by early March 1982. Based on the results of these relaxation tests, physical remedial action may be necessary.
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