05000346/LER-1979-133-03, /03L-0:on 791219,calculations by Itt Grinnell Revealed Seismic Support Design High Pressure Injection Line Exceeded Slenderness Design Ratio.Caused by Failure to Correctly Evaluate Slenderness Ratio.Mods Completed 791223

/03L-0:on 791219,calculations by Itt Grinnell Revealed Seismic Support Design High Pressure Injection Line Exceeded Slenderness Design Ratio.Caused by Failure to Correctly Evaluate Slenderness Ratio.Mods Completed 791223

ML19257B989
Person / Time
Site:	Davis Besse
Issue date:	01/15/1980
From:	Dietrich K TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19257B983	List: 05000346/LER-1979-133, Forwards LER 79-133/03L-0 05000346/LER-1979-133-03, /03L-0:on 791219,calculations by Itt Grinnell Revealed Seismic Support Design High Pressure Injection Line Exceeded Slenderness Design Ratio.Caused by Failure to Correctly Evaluate Slenderness Ratio.Mods Completed 791223
References
LER-79-133-03L, LER-79-133-3L, NUDOCS 8001220505
Download: ML19257B989 (2)

LER-1979-133, /03L-0:on 791219,calculations by Itt Grinnell Revealed Seismic Support Design High Pressure Injection Line Exceeded Slenderness Design Ratio.Caused by Failure to Correctly Evaluate Slenderness Ratio.Mods Completed 791223

Event date:
Report date:
3461979133R03 - NRC Website

text

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Modifications to the seismic support were completed by 0304 li),] l hours on December 23, 1979 under Facility Change Request 79-445.

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER SP-33-79-154 DATE OF EVENT: Dec ember 19, 1979 FACILITY: Davis-Besse Unit 1 1DENTIFICATION OF OCCURRENCE: Design of seismic support 33-CCB-2-H46 on High Pres-sure Injection (HPI) Line 1-1 did not meet the slenderness ratio that is required The unit was in Mode 5, with Power (MWT) = 0, and Conditions Prior t:o Occurrence:

Load (Gross MWE) = 0.

Description of Occurrence: Uhile performing calculations for IE Bulletin 79-02, ITT Grinnell personnel discovered the design of seismic support 33-CCB-2-H46 on HPI Line 1-1 exceeded the slenderness ratio design criteria of 200 used by ITT Grinnell. Tbc analysis was performed assuming the worst case design basis carth-quake loading, however, the analysis failed to correctly evaluate the slenderness ratio.

This design deficiency was discovered while the unit was in cold shutdown during a unit outage.

This incident is being reported in accordance with Technical Speci-fication 6.9.1.8.1.

Designation of Apnarent Cause of Occurrence: The cause of this occurrence was design errors by ITT Grinnell in the initial calculations of the stresses and deflections in this hanger. This design error was discovered while calculating base plate forces and moments for the analysis required by IE Bulletin 79-02.

The error is not due to a general deficiency in the original design methods used by ITT Grinnell but was caused by a failure to correctly evaluate the slerderness ratio for the af fected support.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. This support is not required for normal systen performance but is required only to protect the system f rom a worst case condition of maximum carthquake loading.

HPI String 1-2 was operable if an earthquake had occurred.

Corrective Action

The existing pieces of angle iron were replaced with 3 x 3 x 1/4" and 2 x 2 x 1/4" structural tubing. The affected hanger modifications were completed by 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> on December 23, 1979, prior to the unit returning to operation. Work was performed under Facility Change Request 79-445.

Failure Data: There have been two previously reported similar occurrences, see Licensee Event Reports NP-32-79-08 and NP-32-79-13.

LER #79-133 1783 360