ML20117B452
| ML20117B452 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 08/16/1996 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20117B448 | List: |
| References | |
| NUDOCS 9608270060 | |
| Download: ML20117B452 (3) | |
Text
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2005H001 s...../
i SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION i
RELATED TO AMENDMENT NO. 216 TO FACILITY OPERATING LICENSE NO. DPR-44 PECO ENERGY COMPANY PUBLIC SERVICE ELECTRIC AND GAS COMPANY DELMARVA POWER AND LIGHT COMPANY ATLANTIC CITY ELECTRIC COMPANY i
PEACH BOTTOM ATOMIC POWER STATION. UNIT NO. 2 DOCKET NO. 50-277 t
1.0 INTRODUCTION
i By letter dated June 13, 1996, as supplemented August 7, 1996, the PECO Energy l
Company (the licensee) submitted a request for changes to the Peach Bottom i
Atomic Power Station, Unit No. 2, (Peach Bottom, Unit 2) Technical t
Specifications (TSs).
The requested change permits a one time performance of TS surveillance requirement 3.3.1.1.12 for the Average Pow r Range Monitor
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(APRM) Flow Biased High Scram function with a delayed entry into associated TS Conditions and Required Actions for up to six hours provided core flow is maintained at or above eighty-two percent. The August 7, 1996, letter provided clarifying information that did not change the initial proposed no significant hazards consideration determination.
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2.0 BACKGROUND
The requested change affects Peach Bottom, Unit 2, TS 3.3.1.1 (Reactor i
Protection System Instrumentation).
Specifically, the change affects surveillance requirement (SR) 3.3.1.1.12, which requires a channel calibration, at a frequency of 18 months.
The current surveillance interval j
e'xpires on August 19, 1996, for Peach Bottom Unit 2.
The particular function for which the licensee seeks relief is the flow biased high scram (item 2.b of j
TS Table 3.3.1.1-1).
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This surveillance process deactivates the flow biased APRM scram and the i
calibration process requires about six hours to complete. When one or more l-automatic Reactor Protection System (RPS) trip functions lose their trip i-capability, as is the case for the flow-biased high scram function during the course of the calibration, TS Action item 3.3.1.1.C requires restoration of j
the trip capability in one hour.
The licensee can meet this requirement by i
placing the APRM division which is under calibration, in a tripped condition.
This results in the RPS system being in a half scram condition for the i
duration of the calibration.
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PDR ADOCK 05000277 P
PDR i
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To overcome this problem, the licensee proposed the addition of note 3 to the notes for TS SR 3.3.1.1.12, which would indicate that for the remainder of j
this cycle only (i.e., until the completion of refueling outage 2R11), for surveillance function 2.b, entry into " Associated Conditions and Required t
j Actions", may be delayed up to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> if core flow is above 82 parcent of rated flow. This is indicated as being an exception to Surveillance Requirements Note 2 which permits delay for six hours only if trip capability is maintained, which is not the case for the flow biased trip. The licensee also proposed an addition to the associated TS Basis describing the change and j
indicating that when below 82 percent flow (and APRM setpoints become flow j
biased) associated conditions and required actions must-be entered.
3.0 EVALUATION d
l Peach Bottom Unit 2 is currently in end-of-cycle coast down and is in extended (high) core flow operation to achieve sufficient reactivity to maintain the operation. Core flow is therefore normally above 82 percent flow. The licensee stated that it intends to continue operating above 82 percent core a
flow during the calibration.
In this range of operation the flow biased scram I
is not normally activated and the scram setpoint is clamped at 120 percent of l
high neutron flux (rated thermal power). The Peach Bottom Unit 2 Updated l
1 Final Safety Analysis Report (UFSAR) accident and transient analyses do not i
take credit for the flow biased APRM trip in any accident or transient.
If it were active, the only type of event in which it might play a role would be one in which there would be a flow decrease below 82 percent followed by a power i
increase above the flow biased scram line. This is unlikely in the 5-6 hour i
time Nme of the calibration process, and would be mitigated by the operator 1
action to immediately comply with the associated conditions and required actions when below 82 percent flow.
Without the TS change, the APRM division undergoing calibration must be placed in a tripped condition. With the system in a half scram status the reactor is in increased risk of a full scram from perturbations in the other half of the system during calibration.
It is this increased risk of scram which is avoided by this one time change in the TS.
Following this cycle, Peach Bottom instrumentation involved in this calibration will be upgraded to comply with requirements for a calibration period to match the 24-month operating cycle used for the current cycle and intended for future Peach Bottom Unit 2 operations. The calibrations can then be done between cycles and the proposed
'TS change for this cycle will therefore not be needcd in the future.
Since there is no requirement for the flow biased scram in the Pesch Bottom, Unit 2 safety analyses, a low probability of occurrence of a relevant event during the six hour time frame of the calibration, a benefit to avoiding a possible unnecessary scram, and a proposed solution for future surveillance operations, this one time revision to the TS is acceptable.
. i The staff has reviewed the proposed Peach Bottom Unit 2 TS change for the surveillance calibration specification for the flow biased APRM scram, which permits, for up to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, a delayed entry into associated conditions and required actions, which is in effect a removal of the flow biased scram during the calibration. This scram does not play a role in any Peach Bottom safety analysis, and would have a low probability of being actuated during the calibration time frame.
It is backed up by the normal APRM scram. The TS i
change permits avoiding a half scram status during the calibration and resulting increased potential for an unnecessary scram.
Based on these conclusions the staff has determined that the proposed changes to the Peach Bottom Unit 2 TS are acceptable.
TS page 3.3-6 is reissued aa a result of page reformatting which occurred when revisions to SR 3.3.1.1.12 were inserted. No changes to the TS on the pages issued with this amendment were made other than those described in Section 2.0 above.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Pennsylvania State official was notified of the proposed issuance of the amendment. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendment changes 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 changes a surveillance requirement. The NRC staff has determined that the amendment involves 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 proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (61 FR 34895). Accordingly, the 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 the amendment.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that:
(1) thero 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 amendment will not be inimical to the common defense and security or to the health and safety of the public.
j Principal Contributor:
H.Richings Date: August 16, 1996 i