ML20207K275
| ML20207K275 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 03/02/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20207K269 | List: |
| References | |
| NUDOCS 9903170113 | |
| Download: ML20207K275 (3) | |
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UNITED STATES j
NUCLEAR REGULATORY COMMISSION WASHINGTON. D.C. -8 "1
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.188 l
I TO FACILITY OPERATING LICENSE NO. DPR-24 AND AMENDMENT NO. 193 TO FACILITY OPERATING LICENSE NO. DPR-27 l
WISCONSIN ELECTRIC POWER COMPANY
- POINT BEACH NUCLEAR PLANT. UNITS 1 AND 2 DOCKET NOS. 50-266 AND 50-301
1.0 INTRODUCTION
By letter dated October 7,1998, the Wisconsin Electric Power Company (the licensee) requested amendments to the Technical Specifications (TS) appended to Facility Operating License No. DPR-24 for Point Beach Nuclear Plant (PBNP), Unit 1, and Facility Operating License No. DPR-27 for PBNP, Unit 2. The proposed amendments would incorporate changes to the TS to ensure the 4 kV bus undervoltage input to the reactor trip protective function is controlled in accordance with the design and licensing basis for the facility. An additional administrative change would remove the footnote related to the definition of Rated Power in TS 15.1.J.
2.0 EVALUATION 2.1 Definition of Rated Power The licensee proposes to delete the footnote indicated by
- at the bottom of TS page 15.1-4 and delete reference to the footnote in TS 15.1.J. the definition of " Rated Power." The footnote states:
For Unit 2: If the Reactor Coolant System raw measured total flow rate is <174,000 gpm but 2169,500 gpm, Unit 2 shall be limited to s98% rated power.
The footnote was originally approved by Amendments 165 and 169 to Facility Operating License Noc. DPR-24 and DPR-27 for the PBNP, Units 1 and 2, dated November 17,1995.
The amendments supporte 4 operation of Unit 2 at reduced reactor coolant system flows as a result of increased steam generator tube plugging levels. Subsequently, the Unit 2 steam
. generators were replaced. Operation with the new steam generators was approved by i
Amendments 173 and 177, dated July 1,1997.
l-The analyses supporting Amendments 173 and 177 were performed at a reactor coolant system total flow rate of 181,800 gpm based on an assumed measurement uncertainty of 2.1 9903170113 990302 PDR ADOCK 05000266 P
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- i percent over thermal design flow (178,000 gpm), as reflected in TS 15.3.1.G. Therefore, the footnote is no longer applicable and no longer supported by the approved analyses. The proposed change is supported by the analyses reviewed and approved for Amendments 173 and 177. The footnote should have been removed with the approval of Amendments 173 and 177. The change is administrative and reflects the current approved operation of Unit 2 and is acceptable to the staff.
2.2 Undervoltaae Reactor Trio The licensee proposes to add the existing table footnote " to TS Table 15.3.5-2, " Instrument l
Conditions for Reactor Trip," Item 14.a. "4KV Bus (A01 and A02) Undervoltage (input to reactor trip)," column 3," Minimum Operable Channels." The existing footnote " states:
If a channel is determined to be inoperable, resulting in one less than the total number of channels being operable, pewer operation may continue if the following conditions are met:
- 1. The minimum number of operable channels is still satisf:ed.
- 2. The affected channel is placed in trip within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
As discussed in the PBNP Final Safety Analysis Report (FSAR), Section 14.1.8, the undervoltage reactor trip is the primary protective function credited in the complete lost-of-reactor-coolant-flow analysis. As noted in FSAR Section 7.2.1, primary protective functions are l
designed to meet the criteria of proposed IEEE (Institute of Electrical and Electronics l
Engineers) Standard 279 - 1968, " Nuclear Power Plant Protection Systems," including protection against single failures.
Four kV buses A01 and A02 each supply one reactor coolant pump. An undervoltage on a bus will result in the loss of power to the associated pump. Loss of power to both buses will result in a complete loss of reactor coolant flow. The undervoltage reactor trip protection function is l
. made up of a "one out of two taken twice" channel logic. That is, there are two channels sensing undervoltage on each 4 kV bus, A01 and A02, for a total of four channels. One channel un each bus must sense an undervoltage to make up the trip logic.
The present TS for this function allows an inoperable channel to exist indefinitely with no action required. If one channel on a bus were failed in the untripped condition and the remaining channel on that bus failed to trip during an actual undervoltage condition, an undervoltage on that bus would not be sensed. Since the logic would only sense an undrvoltage on the bus with the two operable channels, the trip logic would not be satisfied and a protective reactor trip l
would be prevented. Thus, the single failure criterion of IEEE 279 is not satisfied for this primary protective function under the existing TS-allowed condition.
l The licensee proposes to make the existing table footnote " applicable to this line item. With the logic for this function, placing one channel on a single bus in trip results in that half of the i
trip logic being satisfied. Therefore, the response of one or both channels on the other bus to an undervoltage condition would result in a protective reactor trip. Since one operable channel can fail and the protective function still be satisfied with an inoperable channel in the tripped condition, the proposed change ensures meeting the single failure criterion required by IEEE 279 and documented in the FSAR.
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3-Placing an inoperable channel on a single bus in the tripped condition will ensure the protective function will be fulfilled assuming a single failure in the remaining channels. When failures occur within the function that would prevent the protective function actuation while assuming a single failure occu s, action is required to place the unit in a hot shutdown condition, where the protective function is not required.
The proposed change will ensure that applicable safety limits are met for the complete loss-of-reactor-coolant-flow event, as analyzed in the FSAR. The proposed change is essentially
- identical to the provisions contained in NUREG 1431, Rev.1, " Standard Technical Specifications, Westinghouse Plants," Section 3.3.1, and is acceptable to the staff.
3.0 STATE CONSULTATION
in accordance with the Commission's regulations, the Wisconsin State official was notified of the proposed issuance of the amendments. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
These amendments change 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. The staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluent that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously published a proposed finding that these amendments involve no significant hazards consideration and there has been no public comment on such finding (63 FR 71978). Accordingly, these amendments meet 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 these amendments.
5.0 CONCLUSION
The Conimission 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 mannet, (2) such activities will ta 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.
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Principal Contributor: C. Lyon Date: March 2, 1999
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