ML20148F419
| ML20148F419 | |
| Person / Time | |
|---|---|
| Site: | Ginna, Yankee Rowe |
| Issue date: | 10/04/1972 |
| From: | Skovholt D US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Vandenburgh D YANKEE ATOMIC ELECTRIC CO. |
| References | |
| NUDOCS 8011050625 | |
| Download: ML20148F419 (2) | |
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OCI PDR l
Docket File I
RP Reading Branch Reading Docket No. 50-29 ACRS (16)
D. J. Skovholt T. J. Carter i
R. J. Schemel Yankee Atomic Electric Company A. Burger ATTN:
Mr. Donald E. Vandenburgh S. A. Teets Vice President D, Knuth 20 Turnpike Road g
Westboro, Massachusetts 01581 4
Gentlemen:
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4 Recent investigation of the performance of unpressurized fuel in soine of the pressurized water reactors presently in operation have verified that separation of fuel pellets and collapse of the fuel cladding into i
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the resulting void have either occurred or are in progress.
In this regard, we advised you in a telephone conversation as early as June 15, i
g 1972, of the fuel performance anomalies discovered at the R. E. Ginna f
Nucicar Power Plant during their refueling in May 1972. These anomalics F(
involved approximately 4% of the fuel rods having collapsed sections of l ye cladding up to 4 inches; approximately 67. of the fuel rods were bowed to
- A7 some degree rather than being perfectly straight. Tne coll psed sections
)k were found only in unpressurized fuel rods. During several recent tele-l phone conversations with your staff, we further discussed with you the interim operating liznitations that are already in effect for a number of 4sg.
pressurized water reactors currently operating with unpressurized fuel; l
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and we indicated the possible need for similar limitations for the Yankee
<f Nuclear Power Plant.
M Because of previous contre ' rod difficulties, you are presently required 337 to operate the reactor at a power level not to exceed 837. of full power if until you shut down the reactor not later than October 31, 1972, for replacement of the control rods. You have reported that the peak linear j:
power as obtained from your evaluations of in-core flux traverses during Q
Core X operation at the reduced power level has not exceeded 7 kW/ft.
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You also have reported that the total primary to secondary leakage in
- l the steam generators has not exceeded 2 gallons per day, j, ':
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4-1972
' 'i Yankee Atomic Electric company ii I
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- m-i We understand that you plan to return the reactor to 600 MWt (full power)
'g after completion of the control rod installation and upon restanption of
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reactor operation. 'Ihere is insufficient evidence that the Yankee unpres-
'C surized zircaloy clad fuel is not susceptible to void' formation and l$
i possible clad collapse. Therefore, we request that you provide the necessary information to justify reactor operation with Core X at 600 MWt.
J7 You should consider restrictions on the average and the linear power in g,-
l the fuel aseemblies, on the total primary to secondary leakage in the steam
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generator, and on the rate of change of power level, taking into account
.Mi all phenomena revealed by the Ginna investigation, including radial shrink-MJ age and axial gaps in pressurised fuel rods as well as unpressurized fuel L% l rods. You also should reexamine' transients and accidents in the Safety Analysis Report and establish any additional limits required for operating
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the reactor, before resuming operation at the and of the outage for control h!
rod replacement.
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?C Sincerely,
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Donald J. Skovholt 6N; ~
Assistant Director
- er for Operating Reactors 3
Directorate of Licensing
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