ML20076L076

Safety Evaluation Supporting Amend 93 to License NPF-30

ML20076L076
Person / Time
Site:	Callaway
Issue date:	10/27/1994
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20076L074	List: ML20076L065 ML20076L076
References
NUDOCS 9411030009
Download: ML20076L076 (2)

Text

.

=

wou 4

UNITED STATES ye 4

i NUCLEAR REGULATORY COMMISSION

• E f

WASHINGTON, D.C. 20666-0001 4

,/

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0. 93 TO FACILITY OPERATING LICENSE NO. NPF-30 UNION ELECTRIC COMPANY e

CALLAWAY PLANT. UNIT 1 DOCKET NO. 50-483

1.0 INTRODUCTION

By application for license amendment dated February 10, 1994, Union Electric Company (the licensee), requested changes to Technical Specification (TS) for Callaway Plant, Unit 1.

The proposed amendment would revise Functional Unit 14 of Table 2.2.1, Undervoltage - Reactor Coolant Pumps, and the associated Bases.

The revision corrects Total Allowance to reflect the measurement and test equipment (M&TE) uncertainty-and the undervoltage relay voltage span. The Trip Setpoint and Allowable Value for Functional Unit 14 are expressed in terms of the bus voltages; and the Total Allowance, Z and S values are expressed in terms of percent undervoltage relay span (70 - 100 V). The Safety Analysis Limit (SAL) of 9384 Vac, the RCP trip setpoint of 10584 Vac, and the Z and S values will not be changed.

The Bases change reflects the relationship between the 13.8 kV_ bus voltages and the 120 V undervoltage relays.

2.0 EVALUATION The reactor coolant pumps (RCPs) receive power from the 13.8 kV buses. One potential transformer is connected in parallel with the 13.8 kV power supply to each RCP at the motor side of the supply treaker.

The purpose of the transformer is to step down the 13.8 kV power supply to a 120 V power supply for an undervoltage relay, a time delay relay, and an underfrequency relay. The undervoltage relays provide signals to the solid state reactor protection system.

The reactor will trip, when greater than 10% rated thermal power, if the voltage at one of two RCP motors in each of the two 13.8 kV buses decreases below the trip setpoint (10584 Vac). The time delay relay prevents spurious reactor trips caused by transient voltage fluctuations.

The undervoltage trip is the primary trip function credited in the safety analysis for a complete loss of reactor coolant flow.

The Total Allowance is the difference between the nominal trip setpoint and the SAL.

As discussed above, the nominal trip setpoint is 10584 Vac, and the SAL is 9384 Vac. The potential transformers for the undervoltage relays have a ratio of 14400:120.

Converting the nominal trip setpoint and the SAL to the equivalent undervoltage relay voltages yields 88.2 V and 78.2 volts, respectively.

In terms of percent span (70 - 100 V), this is 60.7% and 27.3%, respectively. Therefore, the difference between the Total Allowance and the SAL is 33.3%. The current Total Allowance as incorrectly stated in the TS is 7.7%.

The staff finds that the proposed change to the Total Allowance value is appropriate and acceptable.

9411030009 941027-PDR ADOCK 05000483 P

PDR

t

... The revised Allowable Value is 10105 V, which is 84.2 V or 47.4% of the undervoltage relay span.

The licensee stated that the M&TE accuracy for t he. Keithley 197 multimeter is 10.8 V for the 0 - 200 V range, which is the range 1 t would be used for calibrating the undervoltage relays. The 10.8 V accui_y corresponds to i2.7% of the 70 - 100 V undervoltage relay voltage span. The difference between the amended Allowable Value and the SAL is sufficient to account for M&TE uncertainties.

Consequently, the staff finds that this proposed change is also approriate and acceptable.

The staff also reviewed the proposed TS Bases regarding the relationship betwan the undervoltage relay span and the 13.8 kV power supply. The Bases change states that the Total Allowance and Z values for the RCP Undervoltage trip function are based on the percent of the undervoltage relay span, while the Trip Setpoint and the Allowable Value are based on the 13.8 kV buses that power the RCP motors.

The licensee's discussion in the TS Bases addresses the voltage conversion ratio, voltage range, and resultant voltages.

The staff finds these changes acceptable.

3.0 STATE CONSULTATION

In accordance with the Commission's regulations, the Missouri State official was notified of the proposed issuance of the amendment.

The State official had no comments.

4.0 ENVIRONMENTAL CONSIDERATION

The amendment changes a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance reo""ats.

The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the 'ypes, of any effluent that may be released offsite and that there is no sijnificant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that this amendment involves no significant ha m ds consideration and there has been no public comment on such findino (59 FR 14897). Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.

5.0 CONCLUSION

The staff has concluded, based on the considerations discussed above, that:

(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's i

regulations, and (3) the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributor:

M. Waterman Date: October 27, 1994

-