ML20082Q673
| ML20082Q673 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 04/26/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20082Q672 | List: |
| References | |
| NUDOCS 9505010018 | |
| Download: ML20082Q673 (3) | |
Text
_
1 pa"%g
.g.<
81 UNITED STATES j
j NUCLEAR REGULATORY COMMISSION f
WASHINGTON, D.C. 20S6H001
\\,...../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR NACTOR REGULATION RELATED TO AMENDMENT NOS.186 AND 67 TO FACILITY OPERATING LICENSE NOS. OPR-66 AND NPF-73 DUQUESNE LIGHT COMPANY OHIO EDISON COMPANY PENNSYLVANIA POWER COMPANY THE CLEVELAND ELECTRIC ILLUMINATING COMPANY THE TOLEDO EDISON COMPANY BEAVER VALLEY POWER STATION. UNIT NOS. 1 AND 2 QQCKET NOS. 50-334 AND 50-412 1.0 INTRODUCT[QH By letter dated September 2,1992, Duquesne Light Company (DLC or the licensee) submitted a request to amend the Technical Specification (TSs) of operating licenses, DPR-66 and NPF-73 respectively, for Beaver Valley Power Station Units 1 and 2 (BV-1 and BV-2). The proposed amendment to each license would change Note (3) of TS Table 4.3-1, " Reactor Trip System Instrumentation Surveillance Requirements," as it applies to Functional Unit 2.a., " Power Range, Neutron Flux, High Setpoint," of TS Table 4.3-1.
The proposed change to Note (3) of TS Table 4.3-1 would require comparison of the incore to excore axial imbalance at least once every 31 Effective Full Power Days (EFPD) above 15 percent of rated thermal power rather than once every 31 days above 15 percent of rated thermal power.
2.0 EVALUATION Functional Unit 2.m of TS Table 4.3-1 requires various periodic channel calibrations. Note (3) of TS Table 4.3-1 currently requires every 31 days, a comparison of the incore to excore axial imbalance when thermal power is above 15 percent of rated thermal power. This note also requires recalibration if the absolute difference is greater than or equal to 3 percent. The proposed change to Note (3) would require this comparison of incore and excore axial imbalance be performed every 31 EFPD.
The purpose of the incore/excore comparisons is to assure that the excore detectors are accurately representing the flux of the core during its lifetime because, among other functions, they provide input to reactor trip instruments. The excore detectors are in fixed locations on the outside of the core. The quantity of neutrons detected by the excore detectors is 9505010010 950426 PDR ADOCK 05000334 P
V,
~
i proportional to reactor power and will change as the flux profile changes, l
which in turn changes with core burnup. Since the excore detectors are in fixed positions, the output will change with the flux profile. That determines the need for the comparisons with the incore detectors. Howeven because changes in the flux profile depend on core burnup, EFPD is more representative of core burnup than are calendar days.
i The Power Range,' Neutron Flux, High Setpoint reactor trip is actuated when two j
out of four power range channels indicate a power level above a preset setpoint. The Power Range, Neutron Flux, High Setpoint reactor trip is actuated by the output of the excore detectors. The setpoint on the Power Range, Neutron Flux, High Setpoint reactor trip was not changed with this proposal. The proposed change in the incore to excore axial imbalance i
comparison will allow this surveillance to be performed on a basis that is I
representative of core burnup and flux distribution. The requirement to recalibrate if the absolute difference is greater than or equal to 3 percent is not changed by the proposed amendment.
1 The ion chambers (excore detectors) that provide input to the Power Range Neutron Flux, High Setpoint reactor trip also provide input to the Power Range, Neutron Flu,., High Positive Rate reactor trip and the Power Range, Neutron Flux, High Negative Rate. These trips are not affected by the proposed change because they trip on rate of signal increase or decrease. The rate of signal changa is not affected by the incore to excore axial imbalance comparison and which does not change the setpoints for rate of signal change
)
trips.
The Overtemperature and Overpower delta T trips have inputs from the excore
)
ion chambers. These inputs use the difference between top and bottom detector of the power range ion chambers. The trip setpoints for the Overtemperature and Overpower delta T trips are not changed by the proposed change.
l As with any instrument loop, the excore neutron detectors do experience instrument drift. However, the effect of the flux profile change is much greater than the effect of instrument drift.
Instrument loops affected by drift are routinely calibrated on an 18-month frequency.
In the case of the excore neutron detectors, the calibration frequency is chosen to account for the flux profile change. While it is possible that operation at low power levels for a long period of time would allow the incore to excore axial imbalance comparison to be performed infrequently, TS 4.3-1, Functional Unit 2.a. requires a comparison of calorimetric to excore power indication above 15% rated themal power which would correct or account for most of the effects of drift.
The NRC staff has reviewed the proposed changes and concluded that because the incore to excore axial imbalance comparisons are required because of fuel burnup, surveillance intervals based on EFPDs are acceptable.
Further, the setpoints for the various trips are not affected by the proposed changes.
-i s
.a
. ~ - - - -
)
s
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Pennsylvania State official was notified of the proposed issuance of the amendments. The State official had no comments.
4.0 ENVIR0fMENTAL CONSIDERATION The amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change surveillance requirements. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued 'a i
proposed finding that the amendments involve no significant hazards l
consideration, and there has been no public comment on such finding (57 FR-
)
47128). Accordingly, the amendments meet the eligibility criteria for categorical exclusten set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR e-51.22(b) no environmental impact statement or environmental assessment need ~be prepared in connection with the issuance of the amendments.
j
5.0 CONCLUSION
1 l
The Commission 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 regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
1 Principal Contributor: Donald S. Brinkman Date: April 26, 1995 l
l l
l l
- --