NL-10-0318, Request to Revise Unit 2 Implementation Schedule to Delete Reactor Trip System Function 11, Reactor Coolant Pump Breaker Position
| ML100600593 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 02/26/2010 |
| From: | Ajluni M Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-10-0318 | |
| Download: ML100600593 (9) | |
Text
Southern Nucle~F Operatin{J COfTI(lany, lilC February 26, 2010 SOUTHERN A.
COMPANY Docket No.: 50-364 NL-10-0318 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Joseph M. Farley Nuclear Plant - Unit 2 Request to Revise Unit 2 Implementation Schedule to Delete Reactor Trip System Function 11, Reactor Coolant Pump Breaker Position Ladies and Gentlemen:
In accordance with 10 CFR 50.90, "Application for amendment of license or construction permit," Southern Nuclear Operating Company (SNC) proposes to revise the Technical Specifications (TS), Appendix A to Facility Operating License No. NPF-8 for the Joseph M. Farley Nuclear Plant Unit 2.
On March 30, 2009, SNC submitted a TS revision request to eliminate the reactor coolant pump (RCP) breaker position reactor trip function for Joseph M. Farley Nuclear Plant Units 1 and 2. The revision request was approved by the NRC per letter dated September 18,2009 (TAC NOS. ME0982 and ME0983).
Implementation was scheduled for prior to the end of the twenty-third refueling outage (U1 R23) for Unit 1 and prior to the end of the twentieth refueling outage (U2R20) for Unit 2.
SNC is requesting approval to delay the implementation of the Unit 2 amendment for one refueling cycle. The design change is complex and requires coordination of various resources. One of the key items for successful implementation is the design input from the original equipment manufacturer (OEM). Because of unforeseen issues, design inputs from the OEM were delayed, this has challenged outage planning and ability to successfully implement the new design within the scheduled outage window. The impacted activities include work order planning, pre-outage and outage implementation support, development of functional test procedures, and procurement of necessary safety-related cable.
Because of these issues, SNC requests to delay implementation of the Unit 2 design change for one refueling outage, the design change is now to be implemented during the subsequent Unit 2 refueling outage (U2R21), scheduled to begin during October 2011, Operation for an additional cycle with the RCP breaker position trip enabled will have negligible safety consequences given that the configuration of plant equipment currently in place to minimize the likelihood
U. S. Nuclear Regulatory Commission NL-10-0318 Page 2 of an unwarranted trip will remain. There is no modification to the Unit 1 amendment implementation schedule of prior to the end of the U1 R23 (fall, 2010) refueling outage.
SNC requests approval, by May 4, 2010, of the revised Unit 2 amendment implementation schedule, with the amendment being implemented prior to the end of the refueling outage U2R21 for Unit 2. This requested approval schedule will ensure NRC approval prior to the end of the Unit 2 refueling outage (U2R20) currently scheduled to end on May 7,2010.
Mr. M. J. Ajluni states he is Manager - Nuclear Licensing of Southern Nuclear Operating Company, is authorized to execute this oath on behalf of Southern Nuclear Operating Company and to the best of his knowledge and belief, the facts set forth in this letter are true.
This letter contains no NRC commitments. If you have any questions, please advise.
Respectfully submitted,
~~~
M. J. Ajluni Manager - Nuclear Licensing
-fh Sworn to and subscribed before me this 210 day of Fe ~A(J it<..y ,2010.
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Notary Public My commission expires: &,/¢z MJAlJLS
Enclosure:
Basis for the Proposed Change cc: Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. J. R Johnson, Vice President -- Farley Ms. P. M. Marino, Vice President -- Engineering RTYPE: CFA04.054 U. S. Nuclear Regulatory Commission Mr. L. A Reyes, Regional Administrator Mr. R E. Martin, NRR Project Manager -- Farley Mr. E. L. Crowe, Senior Resident Inspector -- Farley Alabama Department of Public Health Dr. D. E. Williamson, State Health Officer
Joseph M. Farley Nuclear Plant Request to Revise Unit 2 Implementation Schedule to Delete Reactor Trip System J Function 11, Reactor Coolant Pump Breaker Position Enclosure Basis for Proposed Change
Joseph M. Farley Nuclear Plant Request to Revise Unit 2 Implementation Schedule to Delete Reactor Trip System, Function 11, Reactor Coolant Pump Breaker Position Enclosure Basis for Proposed Change Table of Contents 1.0 Summary Description 2.0 Detailed Description
2.1 Background
2.2 Proposed Change 3.0 Technical Evaluation 4.0 Regulatory Evaluation 4.1 Significant Hazards Consideration 4.2 Conclusion 5.0 Environmental Consideration
Enclosure Basis for Proposed Change 1.0 Summary Description This evaluation supports a request to revise the implementation schedule for an amendment to Operating License (OL) NPF-8 for Joseph M. Farley Nuclear Plant (FNP),
Unit 2.
On March 30, 2009, Southern Nuclear Operating Company (SNC) submitted a technical specification (TS) revision request to eliminate the reactor coolant pump (RCP) breaker position reactor trip function for FNP Units 1 and 2. The revision request was approved by the NRC per letter dated September 18,2009 (TAC NOS. ME0982 and ME0983).
Implementation was scheduled for prior to the end of the twenty-third refueling outage (U1 R23) for Unit 1 and prior to the end of the twentieth refueling outage (U2R20) for Unit 2.
SNC is requesting approval to delay implementation of the Unit 2 amendment for one refueling cycle. The design change is complex and requires coordination of various resources. One of the key items for successful implementation is the design input from the original equipment manufacturer (OEM). Because of unforeseen issues, design inputs from the OEM were delayed, this has challenged outage planning and our ability to successfully implement the new design within the scheduled out~ge window. The impacted activities include work order planning, pre-outage and outage implementation support, development of functional test procedures, and procurement of necessary safety related cable. Because of these issues, SNC requests to delay implementation of the Unit 2 deSign change for one refueling outage, the design change is now to be implemented during the subsequent Unit 2 refueling outage (U2R21), scheduled to begin during October 2011. Operation for an additional cycle with the RCP breaker position trip enabled will have negligible safety consequences given that the configuration of plant equipment currently in place to minimize the likelihood of an unwarranted trip will remain. There is no modification to the Unit 1 amendment implementation schedule of prior to the end of the U1R23 (fall, 2010) refueling outage.
To proceed with the current implementation schedule for the Unit 2 amendment would challenge FNP's ability to successfully implement the proposed change. Extending the implementation by one refueling outage will allow more time to plan the design change implementation.
2.0 Detailed Description
2.1 Background
On March 30, 2009, SNC submitted a TS revision request to eliminate the RCP breaker position reactor trip function for FNP Units 1 and 2. The revision request was approved by the NRC per letter dated September 18,2009 (TAC NOS. ME0982 and ME0983). Implementation was scheduled for prior to the end of the twenty-third refueling outage (U1 R23) for Unit 1 and prior to the end of the twentieth refueling outage (U2R20) for Unit 2. Due to unforeseen circumstances described herein, SNC is unable to complete the modification for Unit 2 by the end of refueling outage 2R20.
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Enclosure Basis for Proposed Change 2.2 Proposed Change The proposed change is a change to the Unit 2 TS amendment implementation schedule, from implementation prior to the end of refueling outage U2R20 (spring, 2010) to implementation prior to the end of refueling outage U2R21, scheduled to begin during October 2011. There is no modification to the Unit 1 planned implementation schedule of prior to the end of the U1 R23 (fall, 2010) refueling outage.
The conclusions of the significant hazards consideration provided in the SNC letter to the NRC dated March 30, 2009 remains valid and unchanged. The TS pages included in the NRC letter dated September 18, 2009 remain valid and unchanged; however, the interim TS pages will be implemented first for Unit 1 and then for Unit 2.
3.0 Technical Evaluation There is no change to the safety consequences as a result of a change to the Unit 2 TS implementation schedule, from implementation prior to the end of refueling outage U2R20 to implementation prior to the end of refueling outage U2R21, with respect to the current operation. This is because the current configuration (the Unit 2 RCP breaker position power supply will remain aligned to the inverters until implementation of the design change during refueling outage U2R21) will remain.
The approved changes to the TS are supported by a modification to the Reactor Trip System (RTS) that will move the sensing for the RCP undervoltage (UV) reactor trip, TS 3.3.1, Table 3.3.1-1, Function 12, "Undervoltage RCPs," to the motor side of the RCP breakers. This modification will enable the RCP UV sensors to detect the opening of the RCP breakers in addition to bus UV. This modification will make the FNP RTS design similar to other Westinghouse RTS designs that do not contain an RCP breaker position reactor trip function.
The Reactor Coolant System (RCS) low-flow reactor trip, TS 3.3.1, Table 3.3.1-1, Function 10, "Reactor Coolant Flow Low," is the primary reactor trip for a complete loss of RCS flow event. The RCS low-flow function is generated by two out of three low RCS flow signals per reactor coolant loop. Between P-7 and P-810w flow in any two loops will actuate a reactor trip. Below P-7, a reactor trip on low RCS flow is blocked. The RCS low-flow reactor trip ensures that the criterion of maintaining the minimum Departure from Nucleate Boiling Ratio (DNBR) above the limit value is met in the event of a complete loss of RCS flow. The RCP UV reactor trip function and the RCP underfrequency (UF) reactor trip, TS 3.3.1, Table 3.3.1-1, Function 13, "Underfrequency RCPs," provide backup reactor trips for a complete loss of RCS flow.
The RCS low-flow reactor trip is the primary reactor trip for the loss of single-loop flow event. The RCS low-flow reactor trip ensures that the criterion of maintaining the minimum DNBR above the limit value is met in the event of a single-loop loss of RCS flow. Backup reactor trips for partial loss of RCS flow are provided by the overtemperature delta temperature (OTDT) reactor trip, TS 3.3.1, Table 3.3.1-1, Function 6, "Overtemperature AT," and the overpower delta temperature {OPDT} reactor trip, TS 3.3.1, Table 3.3.1-1, Function 7, "Overpower AT."
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Enclosure Basis for Proposed Change The RCS low-flow reactor trip is credited as the primary reactor trip for both loss of RCS flow and partial loss of RCS flow. The FNP accident analyses take no credit for the RCP breaker position reactor trip.
Currently, both Units' RCP breaker position indications are supplied from inverters. The inverters prevent grid perturbations from being experienced downstream of the inverters.
The inverters are the preferred source of power for the AC vital buses because of the stability and reliability they achieve. The function of the inverter is to provide AC electrical power to the vital buses.
The Class 1E inverters provide the preferred source of 120 V, 60 Hz power for the reactor protection system, the engineered safety feature actuation system, the nuclear steam supply system control and instrumentation, the post accident monitoring system, and the safety related radiation monitoring system.
Each distribution panel can be connected to an alternate source of Class 'IE 120 VAC power. The backup power source is an emergency 600 V MCC supplying a 120 V regulated panel through a constant voltage transformer (CVT). Should the normal distribution panel source fail, the inverter static transfer switch will function to supply the vital AC distribution panels from this alternate source.
The inverters have not experienced a failure since 2006. A failure of the inverter will swap the power source to the alternate source. Although a fault downstream of the inverters could cause a plant trip, the inverters have proven to be reliable and afford protection to minimize the likelihood of unwarranted reactor trips. Therefore, the inverters normal alignment will support the enablement of the RCP breaker position reactor trip circuit for one additional cycle.
To proceed with the current implementation schedule for the Unit 2 amendment would challenge successful implementation of the proposed design change. Extending the implementation by one refueling outage will allow adequate time to plan the design change implementation.
The initial schedule for amendment implementation was selected for the earliest possible refueling outages to prevent possible unwarranted reactor trips. The proposed amendment implementation schedule extension will not adversely impact any non-LOCA safety analyses.
4.0 Regulatory Evaluation 4.1 Significant Hazards Consideration Southern Nuclear Operating Company (SNC) has evaluated whether or not a significant hazards consideration is involved with the proposed change to extend the amendment implementation schedule for Unit 2 to fall, 2011 by focusing on the three standards set forth in 10 CFR 50.92(c) as discussed below:
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Enclosure Basis for Proposed Change
- 1. Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?
Response: No.
The proposed Unit 2 amendment implementation schedule extension is administrative in nature and does not require any physical plant modifications, physically affect any plant systems or components, or entail changes in plant operation. The amendment implementation schedule extension does not significantly increase the probability or consequences of an accident previously evaluated in the Final Safety Analysis Report (FSAR). All of the safety analyses have been evaluated for impact. The change in the implementation schedule of the reactor coolant pump breaker position reactor trip and technical specification change will not initiate any accident; therefore, the probability of an accident has not been increased. An evaluation of dose consequences, with respect to the proposed changes, indicates there is no impact due to the proposed changes and all acceptance criteria continue to be met. Operation for an additional cycle with the RCP breaker position trip enabled will have negligible safety consequences given that the configuration of plant equipment currently in place to minimize the likelihood of an unwarranted trip will remain. There is no change to the current licensing basis. Therefore, this change does not involve a significant increase in the probability or consequences of an accident previously evaluated.
- 2. Does the proposed change create the possibility of a new or different kind of accident from any previously evaluated?
Response: No.
The proposed Unit 2 amendment implementation schedule extension is administrative in nature and does not require any physical plant modifications, physically affect any plant systems or components, or entail changes in plant operation. The proposed amendment implementation schedule extension does not create the possibility of a new or different kind of accident than any accident already evaluated in the FSAR. No new accident scenarios, failure mechanisms or limiting single failures are introduced as result of the proposed change. The proposed amendment implementation schedule extension has no adverse effects on any safety-related system. Operation for an additional cycle with the RCP breaker position trip enabled will have negligible safety consequences given that the configuration of plant equipment currently in place to minimize the likelihood of an unwarranted trip will remain. There is no change to the current licensing basis.
Therefore, all accident analyses criteria continue to be met and this change does not create the possibility of a new or different kind of accident from any accident previously evaluated.
- 3. Does the proposed change involve a significant reduction in a margin of safety?
Response: No.
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Enclosure Basis for Proposed Change The proposed Unit 2 amendment implementation schedule extension is administrative in nature and does not require any physical plant modifications, physically affect any plant systems or components, or entail changes in plant operation. The proposed amendment implementation schedule extension does not involve a significant reduction in a margin of safety. All analyses that credit the Reactor Coolant System Low Flow reactor trip function have been reviewed and no changes to any inputs are required. The evaluation demonstrated that all applicable acceptance criteria are met. Operation for an additional cycle with the RCP breaker position trip enabled will have negligible safety consequences given that the configuration of plant equipment currently in place to minimize the likelihood of an unwarranted trip will remain. There is no change to the current licensing basis. Therefore, the proposed amendment implementation schedule extension does not involve a significant reduction in the margin of safety.
4.2 Conclusion Based on the preceding evaluation, SNC has determined that the proposed amendment implementation schedule extension meets the requirements of 10 CFR 50.92(c) and does not involve a significant hazards consideration.
5.0 Environmental Consideration An environmental assessment is not required for the proposed change because the request conforms to the criteria for actions eligible for categorical exclusion as specified in 10 CFR 51.22(c)(9). However, Southern Nuclear Operating Company has evaluated the proposed amendment implementation schedule change and has determined that the proposed change does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in the individual or cumulative occupational radiation exposure. Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), an environmental impact statement or environmental assessment of the proposed amendment implementation schedule change is not required.
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