ML19094B462
| ML19094B462 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 07/10/1975 |
| From: | Stallings C Virginia Electric & Power Co (VEPCO) |
| To: | Goller K Office of Nuclear Reactor Regulation |
| References | |
| Download: ML19094B462 (2) | |
Text
'"
e Mr. K. R. Goller, Assistant Director for Operating Reactors Division of Reactor Licensing Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D. C.
20555
Dear Mr. Goller:
Docket License AMENDMENT TO THE OPERATING LICENSES TECHNICAL SPECIFICATION CHANGE NO. 16
- SURRY POWER STATION-UNIT NOS. 1 AND 2*
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Nos. DPR-32 DPR-37 Enclosed herewith is additional information requested by the Regulatory Staff to assist in the review of Technical Specification Change No. 16 con-cerning steam flow setpoints.
A meeting between Vepco representatives and the Regulatory Staff was held on June 13, 1975 to discuss the concerns of the Commission and, as agreed, the information contained hereinbelow responds to those concerns identified.
The specific concern of the Staff is that assurance was required, prior to approval of the setpoint change, to indicate that 11 per cent of the 100 per cent nominal heat flux at the desired setpoint was not exceeded.
At the meeting we indicated that preliminary analytical work had been performed for a steam line break at 50 per cent steam flow at zero power with the emergency core cooling system (ECCS) injection system signal generated by low pressurizer pressure and level rather than the differential pressure setpoint.* It was agreed that this analysis would bound the desired 40 per cent setpoint and that the submittal of the results of the analysis verifying that the resultant heat flux was acceptable would satisfy the Staff's concerns.
Presented here-
.inbelow are the results of the analys;i.s which demonstrates acceptability.
The steamline break analysis was* performed for a break of 0.75 ft 2 tot~l area or 0.25 ft 2 per steam generator.
A break of this size results in an initial steam flow slightly greater than 50 per cent of the nominal flow at nominal steam pressure.
The analysis showed that the break flow decreased to
- below 40 per cent of nominal just before coincidence with low steam pressure
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Mr. K. R. Goller Page 2 or low T-ave~age could be obtained.
Consequently, the analysis only took credit for safety injection on coincident low pressurizer pressure and level, occurring 27.5 seconds following the start of the transient.
The peak core thermal power occurred at 64.0 seconds and reached only 5.1 per cent.
This is well below the peak thermal power of 15.8 per cent reported for the hypo-thetical break in the licensing submittal for the reload for Unit Nos. 1 and 2.
As a result of this analysis, it has been shown that the increase in high steam flow setpoint from 20 to 40 per cent of nominal _steam flow does not result in consequences more severe than the applicable limits for this incident.
We believe that the analysis performed provides the information requested and that approval of our request should be granted.
Very truly yours,
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C. M. Stallings*
Vice _President-Power Supply and Production Operations