ML19309A209

Transfers Lead Responsibility Re Investigation of Prestress Sys Tendon Failure

ML19309A209
Person / Time
Site:	Rancho Seco
Issue date:	04/05/1974
From:	Grier B US ATOMIC ENERGY COMMISSION (AEC)
To:	Moore V US ATOMIC ENERGY COMMISSION (AEC)
References
RO-C&O-74-4, NUDOCS 8003260914
Download: ML19309A209 (2)

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'qpo J 837',e Serial No.:.RO-C&O-74-4

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V. A. !!oore, Assistant Director, Li ht Water Reactors, Grcup 2, L d

S;.ibj ect : VSL Prestrcss System Faciliev: Rancho Seco - Docket ho. 50-312

' tent.onsible 20 Acaictant Director:

B. H. Grier Lecerfption of Itsu Raquirinn Resolution:

The applicant has conducted an inservice surveillance test en tendon H50.

Thic is a 56 strand tenlon of which 5 strande had slipped thron;:h the grips and 5 atrands had clinped in the grips from.3/4 cf an inch to eight iachen. The jack used in the test could only engage 46 of the atrande. These strands were stresced until they cane free of the conc grippera in the' washer and ccrried their proportionate chare of the load.

When the strand ccma free o' the grippcts in the vasher the outer wires in some of the otrands startcd to break. The wires that broke failed in a trittle mannte through catches produci d by the jacking apparatus.

n The applicent is making a study of the failure c:echnnicm and testing V)

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ciethods, he propones te ptrfern lift off tests on a tendon installed in a test bcd 2t c tacting facility to be specified later.

RO Reco:rmandacions and Proposed Cource of 4.

u 1.

The Directorate of Licensing will review the VSL prestressing system as installed at thin facility to determine whether the fcilura is attributable solely to abnormal (beyond design) stresses induced by the test apparctus or tect procedures, thus, limiting resolucion of this prcbl e, co requiring improvenents in the test apparctus-or test proceduras L.cing utilized.

2.

In the cvent that the failurn c.cchanism is not found to be casociated solely with the cos: apparatus or test procedures, the Direccurate of Licensir:; will revici the VSL installation itself to either conclude that the dc+ree of degradation coupled with the er.isting tendon g

surveilinnee progrca ic neceptable or reonire tric necessary design ocdifi:ations or improvecents in the surveillance program to resolve this' problem..

3.: The Directorate of ne'platory Operatiors will pro / _de infcatation crith respect to the insta11ccion, test apparatu6 and test ncocedurce actually involved during thclatove occurrence es daemed necessary in aupport of l'and 2 chave.

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2-APR 5 1974 i

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TPR!Str.R Cr LEAD RESPO!!SIBILITY

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The Directorate of Regulatory Operations will review and report on any additional testing performed by.the manufacturer or installer.-

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5.. The Directorate of Regulatory Operations.will verify adherence to-.

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j any Technical Specification changes, tect changes, or 'desi;;n modifi-

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cationc to the VSL system itself as dee:cd necessary based on the j-results:of 1 and 2 above as appropriate.

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6.

In the event that the test apparatus or procedures are found to be i

deficient, the Directorate of Regulatory Operations will. investigate l

uhcre QA control broke down.

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