ML19260A723

LER 79-087/01T-4:on 791004,noted That Seven Nuclear Svcs Closed Cycle Cooling Sys Hangers Failed to Meet Safety Requirements Per IE Bulletin 79-02.Caused by Inadequate Hanger Design.Mod 79-6-86F Initiated to Rework Hangers

ML19260A723
Person / Time
Site:	Crystal River
Issue date:	11/20/1979
From:	Lancaster K FLORIDA POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19260A718	List: ML19260A717 ML19260A723
References
LER-79-087-01T, LER-79-87-1T, NUDOCS 7912030157
Download: ML19260A723 (3)

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1456 045 7912oao /U

SUPPLNTARY INFORMATION Report No.: 50-302/79-087/0lT-4 Facility: Crystal River Unit #3 Report Date: 20 November 1979 Occurrence Date: 4 October 1979 Identification of Occurrence:

Inadequate design of seven (7) Nuclear Services Closed Cycle Cooling (SW) System hangers reportable under 6.9.1.8.1.

Conditions Prior to Occurrence:

Mode 1 power operation (100%)

Description of Occurrence:

At 1815, following an engineering evaluation conducted by Gilbert Associated, it was reported that seven (7) Nuclear Services Closed Cycle Cooling (SW) System hangers did not meet the requirements of IE Bulletin 79-02. Sw System hangers SWH-404A, 429A, 431A, 432A, 449A, 451A, and 478A, all had a safety factor less chan two.

Designation of Apparent Cause:

The cause of this event is attributed to inadequate design.

Analysis of Occurrence:

No effect upon the plant or general public. Justification is provided for the continued operation of the plant with seismic 1 supports having anchors with safety factors less than two (2) as reported by LER 79-087/0lT-0.

The supports are located on Nuclear Services Closed Cycle Cooling System piping inside containment at the secondary shield vall penetrations accessible freu outside the secondary shield wall.

Each of the piping lines is similar with the piping coming off

. the main headers rising up the shield and turning through the penetration. The supports are classified Seismic 1 to maintain the integrity of the piping which acts as a containment isolation boundary inside containment. There are automatic isolation valves

, on these lines outside containment to give the double isolation boundary consistent with FSAR requirements. This piping is not required foi safe shutdown of the reactor. There are manual isolation vr.1ves at the base of each riser off the main headers.

The loads ou these supports are due to deadicad, thermal and seismic with the seismic portion being rwice the value obtained from an analysis which utilited the Operating Basis Earthquake.

This combination of leads provides a resultant load that produces a safety factor of less than two (2) for the anchor bolts. If cne 03E seismic load is used in combination with the deadweight and ther=al loads, the safety factor is greater than two (2).

1456 046

Supplementary Information LER 50-302/79-087/0lT-4 Page 2 The seven (7) supports each have three (3) supports upstream and downstream which meet the factor of safety criteria given in Bulletin 79-G2, Corrective Action:

Modification 79-6-86F has oeen initiated to repair the affected hangers to provide a minimum safety factor of two (2). It was originally assumed that repair of the supports could be made with the plant in operation. Further investigation revealed that although the supports are accessible during plant operation, welding to.the piping will be required. To perform the welding and to assure an acceptable weld safely, the associated piping should be drained. Repairs will be completed during the next plant outage.

Failure Data:

This is the second occurrence of this type reported. Refer to LER 79-61.

/rc 1456 n47