ML19276H352
| ML19276H352 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 02/21/1974 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | Schwencer A US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML19276H353 | List: |
| References | |
| NUDOCS 7910160690 | |
| Download: ML19276H352 (1) | |
Text
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A. Schwencer, Chief Light Water Reactors Branch 2 and 3, L METROPOLITANEDISONCCMPhNY-THREEMILEISLANDUNITNO.1-DOCKET NO. 50-239 The licenseds report (Enclosure 1) discusses his decision to not return deficient safeguards motors to the manufacturer for modifications.
In our view, the licensee has not considered the appropriate reduced voltage conditione in evaluating the acceptability of these motors.
The requirements in the purchase order specify that the puicp motors shall be capable of accelerating all losls from rest to operating speed within six seconds even when the supply voltage is only 80%
of rated. Racalculations by Westinghouse indicated that it would take 11.4 seconds to reach operating speed at 801 voltage. However, the possibility exists that full speed may not be reached and that a "high slip" (underspeed) condition may occur at 801 voltage in which casa the motor would trip out on overload.
The licensee's decision to accept the motors is based on the assumption that a reduutd voltage condition could exist for only 1.12 seconds (the voltage recovery time of the diesel generator), and that a prolonged under voltage condition need not be considered.
In our opinion a prolonged under voltage condition is credible. Therefore, we recommend that the licensee be required to provide motors that meet the original design requirements and that tests demonstrating conformance be made.
These recotsmendations were discussed with R. 3cnero, L on February 14 by Vince Thomas, RO.
Should you have questions concerning this natter please contact Vince on Ext. 7461.
1413 M8 nl I. V. Seyfrit, Chief Technical Assistance Branch, R0
Enclosure:
Letter, Metropolitan Edison Company to D. F. Knuth, dated February 4, 1974 f,
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