ML19210D141

Final Deficiency Rept Re Tensile Anchor Capacities Lower than Assumed in Design Allowables.Progressive Cracking Occurred in Welded Stud Anchors.Plate Flexibility Problems Eliminated by Use of Knee Brace Brackets

ML19210D141
Person / Time
Site:	05000524, Hartsville, Phipps Bend
Issue date:	10/26/1979
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML19210D105	List: ML19210D104 ML19210D141
References
NCR-CEB-79-16, NCR-CEB-7917, NUDOCS 7911200579
Download: ML19210D141 (1)

Text

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HARTSVILLE AND PHIPPS BEND NUCLEAR PLANTS NCR CEB 79-16 AND CEB 79-17 10CFR50 55(e) REPORT NO. 3 -(FINAL)

TENSILE ANCliDR CAPACITIES LOWER THAN ASSUMED IN DESIGN ALLOWA3LES Description of Deficiency Progressive cracking of the heat affected zone of welded stud anchors in flexible plate connections has occurred in TVA general research and development tests. This results in lower tensile anchor capacities than assumed in establishing design allowables.

Safety Imolications Statement -

Based on the results and conclusions of the testing program, a review of welded anchorages found the anchorages for heavy embed:ents were adequate and would perform as designed under design losdings. For eded ents subject to scall loadings / bending =ocents, their ability to withstand their design loadings cannot be determined except by actual testing of each e: bed ent.

Therefore, it is conservatively assumed that had the deficiency gone uncorrected, design loadings could be exceeded for these embed ents. Since some portions of the safety syste=s are supported by these embed:ents, the safe operation of the plcnt could have been adversely affected.

Corrective Action When this problem was discovered, a testing program was initiated to qut.ntify the effect of plate flexibility on stud capability. The results of the tests are contained in CEB Report 79-18 (attechnerd 1).

A review of welded stud attach =ents for safety-related systens within the balance-of-plant at Hartsville and Phipps Bend was conducted to verify the plant's compliance with CEB Report 79-18. Plate flexibility problems were eliminated in heavy embedments by utilising knee brace brackets instead of cantilever brackets, thus eliminating high bending moments on the plates.

The decision to add these knee brackets was made before this discovery of the tensile anchor capacity problem and, therefore, was not performed .

I as corrective action for the problem.

For e= bed ents subject to smil loadings / bending =ccents, cantilever brackets and the test data of CEB Report 79-18 vere utilized for codification of the structural deflection design of the affected e= bed ents.

As a result of the review conducted, TVA has deter *--d that the anchore.ges at Hartsville and Phipps Bend Nuclear Plants are now adequate.

A rJ 7911200 b

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