ML20069K056

Startup Rept for Wolf Creek Generating Station Power Rerate & T Hot Increase

ML20069K056
Person / Time
Site:	Wolf Creek
Issue date:	06/09/1994
From:	WOLF CREEK NUCLEAR OPERATING CORP.
To:
Shared Package
ML20069K053	List: ML20069K049 ML20069K056
References
NUDOCS 9406150234
Download: ML20069K056 (2)

Text

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Aftachment to ET 94-0053 Page 1 of 2 STARTUP REPORT FOR WOLF CREEK GENERATING STATION POWER RERATE AND Tavg INCREASE d INTRODUCTION This report describes the testing that supported the increase in heactor Coolant System (RCS) full power average temperature (Tavg)from 581.2 F to 586.5 *F, and an associated incraase in reactor thermal output from 3480 to 3565 MWt, at the Wolf Creek Generating Station (WCGS). This report is a supplement to the Startup Report submitted on February 18, 1994 (letter ET 94-0020, from F. T. Rhodes, WCNOC to NRC) and is submitted as required by Sections 6.9.1.1, 6 . 9.1. 2, and 6.9.1.3 of the WCGS Technical j Specifications. The previous report, submitted under letter ET 94-0020, I indicated that the generator output breakers had been modified due to revised amperage requirements. Although this had been identified as a pre-outage (the sixth refueling outage) task, subsequent analysis indicated that this modification would not be required, and was not performed.

I The license amendment request for approval to operate with limiting safety j system settings relating to the RCS average temperature increase was  !

submitted on February 7, 1994 (letter NA 94-0018, from R. C. Hagan, WCNOC to NRC). This submittal contained evaluations demonstrating that the Nuclear Steam Supply System and Balance of Plant systems had been reviewed and found capable of meeting all applicable safety design bases and power generation bases as defined in the Updated Safety Analysis Report, at the uprated conditions. This submittal was subsequently approved and issued by the NRC on March 3, 1994, as Amendment No. 72 to the WCGS Operating License.

This report represents the results of implementation of Amendment No. 72 to the WCGS Operating License. The primary goal of the T avg inu ease program was to obtain an increase in electrical output.

Reactor thermal output presented in this report is based on feedwater flow that, due to venturi fouling, was indicating about 1.4  % higher than actual.

IMPLEMENTATION OF THE POWER RERATE Changes were made to the WCGS Technical Specifications concerning Tavg j limitr, Axial Flux Difference limits, Over-Power and .Over-Temperature .iT trip setpoints, and instrument accuracy and response times.

An engineering calculation was performed to determine the minimum allowable RCS flow indication (less than 0.5% adjustment) for the density change due to increase in design Tcold from 549.3 F to 554.8 F. No change was made to the low flow trip setpoints because there was sufficient conservatism in the present setpoint to accommodate the flow change due to coolant density decrease in the cold leg of the RCS (a density decrease results in a conservative change in the indication from the prior calculation based on 549.3 F for Tcold)-

Flux maps were taken before rerate implementation to verify core parameters were within acceptable limits, and compared to 3565 MWt rated power to predict post-rerate acceptability. Results showed sufficient margin existed to allow escalation to the Rated Thermal Power level (3565 MWt) 0406150234 940609 ,,,

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Attachment to ET 94-0053 Page 2 of 2 Daseline data and component rescaling for the T avg increase was commenced on March 7, 1994, and final data ai the new T avq nd necessary component rescaling was completed on March 17, 1994. Proce~ dure and software changes were prepared prior to implementation of the T avg increase and issued as directed by the implementing procedure. Implementation was conducted under temporary procedure, TP-EN-159, " Power Uprate and Tavg Increase."

Rescaling of components was accomplished at approximately 3480 MWt. This was done prior to commencement of power increase to the design uprate power l value of 3565 MWt. P; ant calorimetric data was taken and Power Range Nuclear Instrumentation (NI's) adjusted whenever changes were made which could affect accu 8dcy of the NI's. Major component and tra nsmitter rescaling and recalibration, along with power ascension to 35C5 M 4t , were completed on March 10, 1994. Turbine Control Valves were 95 's open at the power level of 3565 MWt. Rescaling and recalibration of selected l components that were determined to be outside the desired tolerance limits, l were completed at the full power level.

l The power uprate and Tavg increase resulted ir. electrical output of about 1221 Mde at the Rated Tnermal Power level, an increase of about 29 MWe.

TESTING Testing included collecting baseline and full power data for the following components: vibrations for the turbine generator, feedwater pumps, condensate pumps, and reactor coolant pumps (RCP) ; walk downs and inspection of pipe hangers for predetermined feedwater, condensate, and steam lines; trending using the plant computer for predetermined primary and secondary component parameters; and biological shield surveys at the l maximue achieved power level. The results of the testing showed the plant I operated at the new increased T avg, within expected ranges, and there was no noticeable increase in vibration or component degradation at Rated Thermal Power.

Balance of Plant data was taken for condensate, feedwater, main steam, and reheat steam systems. The values for this data remained within expected levels at Rated Tnermal Power. The generator and associated components were monitored during the uprate and component values remained at acceptable levels. Pipe hanger inspections on feedwater and steam lines showed no adverse pipe movements as a result of changes in flows and temperatures. The biological shield survey at Rated Thermal Power based on feedwater flow calorimetric chowed no change in containment radiation levels at the monitored points. '

Flux maps were again taken at the maximum achieved power level to verify core parameters were within acceptable limits. Results showed acceptable margins existed for F q and Fah, and the core to be performing within acceptable design limits.

Initial full power AT's were extrapolated from measured values at I approximately 3480 MWt and compared with expected full power AT's following 1 l

implementation. The differences were small enough to maintain initial calibration until after implementation. Final values for AT's were determined at Rated Thermal Power, and the necessary adjustments I implemented.

i Turbine Impulse pressure and Tref were rescaled to Rated Thermal Power with '

Tavg equal to Tref where current values were greater than one-half of allowable tolerances of the current scaling.

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