ML20067C013
| ML20067C013 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 02/18/1994 |
| From: | WOLF CREEK NUCLEAR OPERATING CORP. |
| To: | |
| Shared Package | |
| ML20067C010 | List: |
| References | |
| NUDOCS 9402250244 | |
| Download: ML20067C013 (3) | |
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Attachment to ET 94-0020 Page 1 cf 3 STARTUP REPORT FOR WOLF CREEK GENERATING STATION POWER RERATE AND THOT REDUCTION INTRODUCTION 3
This report describes the testing which supported the increase in licensed power at the Wolf Creek Generating Station (WCGS) from 3411 Megawatt thermal (MWt) to 3565 MWt and a decrease in Reactor' Coolant System (RCS) average temperature from 588.5 F to 581.2 F.
This report is submitted as required by Sections 6.9.1.1, 6.9.1.2, and 6.9.1.3 of the WCGS Technical-Specifications.
The license amendment request for approval to operate at 3565 MWt and
. limiting safety system settings relating to RCS average temperature reduction was submitted on January 5, 1993 (Letter NA 93-0001, from R.
C.
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 November 10, 1993, as Amendment No. 69 to the WCGS Operating License.
There were two primary goals of the power rerate program:
1) in& eased electrical output, and 2) life extension for steam generators by reducing primary average temperature, i.e., Thot reduction.
Following is a summary of the results of the implementation of Amendment No.
69 to the WCGS Operating License.
IMPLEMENTATION OF THE POWER RERATE i
A portion of the changes required to support the power rerate were made during the sixth refueling outage starting in March, 1993.
These included:
changes to technical specifications concerning overall instrument response times, replacement of electrical conductors between the main transformers and the switchyard, adding additional cooling to the main transformers, and modifying the generator output breakers due to revised amperage i
requirements.
An engineering calculation was performed to determine the minimum allowable RCS flow indication (less than 1. 0 % adjustment) for the density change due to reduction in Tcold.
No change was made to the low flow trip setpoints i
because there was sufficient conservatism in the present setpoint to accommodate the flow change due to coolant density increase in the cold leg of the RCS.
i Fluxmaps were taken before rerate implementation to verify core parameters were within acceptable limits, and were compared to predicted 3565 MWt
'I rated power to determine post rerate acceptability.
Results showed sufficient margin existed to allow escalation to the new rated thermal power level.
The power rerate and Thot reductior. was initiated on November 17, 1993, and completed on December 21, 1993.
Procedure and software changes were prepared prior to implementation of the rerate and issued during the rerate as directed by the implementing procedure.
Implementation was conducted under temporary procedure TP TS-154,
" Power Rerate and Thot Reduction. "
Rescaling of components was accomplished at approximately 3240 MWt, prior 9402250244 940218 PDR ADOCK 05000482 P
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l Attachment to ET 94-0020 Page 2 of 3 i
l to commencement of power increase to the new design rerate power value of i
3565 MWt.
Plant calorimetric data was taken and Power Range Nuclear instrumentation (NI's) adjusted whenever changes were made which could affect accuracy of the NI's.
WCGS was able to reach only 3417 MWt, following completion of major component and transmitter rescaling and recalibration, with the turbine control valves in the wide open condition.
{
rhe plant was put in a safe, stable configuration, at this. power level, 1
prior to !!ovember 24, 1993.
A plan was developed to safely increase the generator electrical output, since it was approximately 14 MWe below its electrical output prior to rerate implementation.
The potential of encountering this condition had been identified prior to implementation.
l After careful review by WCNOC Nuclear Engineering personnel, it was determined that T c uld be safely raised, within safety limits, above avt the Tref target value to increase steam pressure, thus resulting in an increased generator output.
Procedure TP TS-154 was revised to allow T av to be raised above Tref.
This resulted in an increase in electrica$
output of about 21 MWe with reactor power at about 3480 MWt.
TESTING i
Testing included collecting bmli.'e and power ascension data on the j
following components:
vibration for the turbine generator, feedwater
- pumps, condensate
. umps, and reactor coolant pumps; walkdowns and inspection of pipe hangers for predetermined movement of feedwater, condensate, and steam lines-trending using the plant computer for predetermined primary and seccndary component parameters; and biological l
shield surveys at the maximum achieved power level.
The results of the testing showed the plant operated at a reduced Thot, within expected ranges, and there was no noticeable increase in vibration or component degradation at the maxit u achieved power level.
i Balanc-> of Plant data was taken for indensate, feedwater, main steam, and i
reb 9 team systems.
The values 1 - this data remained within expected lev.
for the achieved power level.
.The generator and associated compu its were monitored during the rerate 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 the maximum achieved power level showed no change in containment radiation levels at the monitored points.
1 Fluxmaps were again taken at the maximum achieved power level to verify core parameters were within acceptable limits.
Results showed acceptable margins existed for F and F3h, and the core to be performing within q
acceptable design limits.
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Preliminary full power N"r were extrapolated from measured values at approximately 3240 MWt with T at the new lower reference value, and avg input into the reactor protection circuitry.
Operation at the maximum achievable power levcl resulted in numerous AT and T deviation alarms.
avg This had been anticipated due to power effects on the upper plenum anomaly.
The T deviation alarms were investigated by Reactor Engineering av personnefanddeviationsetpointsraised to prevent nuisance alarms.
The AT alarms were addressed by the final calibration of AT.
Final values for AT's were extrapolated to 100% of rs.ted thermal power after determination of maximum achievable power level with turbine control valves in the wide open cendition and T above Tref.
Final AT values were within 0.5% of' avg calorimetric power values at the maximum achieved power level.
1 i
m.
.,m,.
L 1
Attachment to ET 94-0020 Fage 3 of 3 Turbine impulse prescure and Tref were not rescaled to the new power level with the turbine control valves in the valves wide open condition and I
increased T condition.
An examination of allowable operation with T avg avg 5 3*F above Tref verified agreement with the design values.
A license amendment request was submitted on February 7,
1994 (Letter NA 94-0018, from R.
C. Hagan, WCNOC to the USNRC) to decrease the 5'F Thot i
reduction requested in our original subrittal.
This submittal includes j
additional revisions to rerate parameter setpoints (e.g.,
overpressure AT and overtemperature AT).
These changes will allow WCGS to achieve its goal j
of increase electrical output for the remainder of Cycle 7.
An additional report describing actions taken to achieve 3565 MWt will be submitted i
within 90 days of completion of those actions.
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