ML13331B195
| ML13331B195 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 06/19/1989 |
| From: | Nandy F Southern California Edison Co |
| To: | NRC/IRM |
| References | |
| NUDOCS 8906230190 | |
| Download: ML13331B195 (2) | |
Text
-
e 7
Southern California Edison Company P. 0. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 F. R. NANDY TELEPHONE MANAGER OF NUCLEAR LICENSING (818) 302-1896 June 19, 1989 U. S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D.C. 20555 Gentlemen:
Subject:
Docket No. 50-206 Limitation on Start - Stops of Standby Diesel Engines San Onofre Nuclear Generating Station Unit 1 Amendment No.
123 to the San Onofre Unit 1 operating license, issued on April 14, 1989, imposed a license condition applicable to plant operation during Cycle 10.
License condition number 3.L(1) requires that the number of start-stops on. each standby diesel engine be limited to no more than fifty between successive inspections of the crankshaft oil holes. SCE has the following comments on this requirement.
The purpose of the crankshaft oil hole inspections is to look for new crack indications that may result from excessive torsional stresses on the crankshaft during transient operating conditions. The crack growth under various assumed conditions was analyzed by Failure Analysis Associates (FaAA) in Revision 1.0 of Report No. FaAA-84-12-14, which is presently under NRC review. The number of start-stops recommended between successive inspections was based on the number of start-stop cycles that a pre-existing crack would take to propagate to a depth where the crack becomes self-propagating under full-power steady state load.
Each start-stop was assumed in the report to consist of a start (a "worst case" fast start),
two hours of steady state operation at 6000 kW and 450 rpm, and a coastdown.
Analysis has shown that crack growth can proceed only when the high stresses associated with the critical speeds are experienced. Table 3-1 and Figure 3-1 of the FaAA report show the major critical orders and their corresponding engine speeds to be as follows:
ORDER ENGINE SPEED (RPM) 5 1/2 217 5
240 4 1/2 264 B9623019 0 13906 PpDR ADOCK PHU
Document Control Desk
-2 If the crankshaft speed is less than 200 rpm, it is not subjected to the high stresses which can contribute to crack growth and which are of concern in FaAA's analysis.
Based on the foregoing discussion, it is SCE's conclusion that engine start stop cycles in which engine speed does not exceed 200 rpm need not and should not be counted toward meeting license condition number 3.L(1) requirements.
If there are any questions, please call me.
Very truly yours, cc:
J. B. Martin, Regional Administrator, NRC Region V F. R. Huey, NRC Senior Resident Inspector, San Onofre Units 1, 2 and 3