ML19308C022
| ML19308C022 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco, Crane |
| Issue date: | 03/20/1978 |
| From: | BABCOCK & WILCOX CO. |
| To: | |
| References | |
| TASK-TF, TASK-TMR NUDOCS 8001170763 | |
| Download: ML19308C022 (2) | |
Text
SI1WT GBERNIUt ANAI,YSIS PERIV.'BIED BY l
BfM ON SMJD 000LD0;N INCIDIWf 0F 3/20/78 A prvlir.dnary" assessent of the potential dsmge to the SMJD Steam Generators during tlw 3/20/78 rapid cooldown transient at Itancho Seco has been completed by Itabcock 6 Wilcox.
Based on that assessment,144 feels that the steam Generators iham not been adversely affected.
This evaluation is based on an analysis of the ntresses inposed on the tubes, tuba-to-tubesheet welds, and head-to-tubesheet we.1d. To assess whether or not the tube yield strength was exceeded, an estirmate of avenge shell temperature vs.
tir.m was trade. A plot of the average shell temperature calculated is shown in the attached figure (Note that average tube tercerature is equal to RC cold log tencrature).
From this calculation, the rn2xirnum ttd>c-to-shell tenperatum differential (AT) is 170 F at 0515 hours0.00596 days <br />0.143 hours <br />8.515212e-4 weeks <br />1.959575e-4 months <br /> (50 ninutes into the transient).
A structural analysis was perforned by the Cor@onent Designer which demonstrated that a 200 F AT is acceptable without exceeding tube yleid strength or without trq osing imacceptable stresses in any of the welds mentioned pmviou-ly and further meets the requircrients of A90. Code Section III.
In addition, we have evaluated the fatigue usage factor and cro convinced that the usage has not been appreciably increased. This will be determined and m ported in the final mport of this incident.
9 8001170763
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