NOC-AE-06002101, Proposed One-Time Exigent Change to Loss of Power Instrumentation Technical Specifications

Proposed One-Time Exigent Change to Loss of Power Instrumentation Technical Specifications

ML070160054
Person / Time
Site:	South Texas
Issue date:	12/28/2006
From:	Halpin E South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-06002101, STI: 32104070
Download: ML070160054 (16)

Text

Nuclear Operating Company South Txas pro/ect Electric Genelating Station P0. Box 289 Wadsworth Texas 77483 - - - - -A

• December 28, 2006 NOC-AE-06002101 10CFR50.90 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738 South Texas Project Unit I Docket Nos. STN 50-498 Proposed One-Time Exigent Change to Loss of Power Instrumentation Technical Specifications

Reference:

Letter dated December 20, 2006, from E. D. Halpin, STPNOC, to NRC Document Control Desk, "Proposed One-Time Exigent Change to Loss of Power Instrumentation Technical Specifications" (NOC-AE-06002096)

STP Nuclear Operating Company (STPNOC) submits the attached proposed' amendment to South Texas Project Unit I Operating License NPF-76. This license amendment request proposes a one-time exigent change to revise Technical Specification (TS) 3.3.2 requirements for loss of power (LOP) instrumentation (Functional Unit 8). This submittal revises the proposed TS wording in the referenced correspondence. The No Significant Hazards Determination in the referenced submittal still applies and is not changed by this revision.

One channel of STP Unit I LOP instrumentation is currently inoperable and in the tripped condition per TS action requirements. Corrective maintenance will require a second channel to be made inoperable and STP TS have no action for two inoperable channels. Consequently TS 3.0.3 would apply. STP is proposing to revise the LOP TS such that the corrective maintenance can be performed without the need to enter TS 3.0.3. Because operating with one channel of LOP instrumentation in trip increases the potential for an inadvertent ESF actuation (ESF bus strip and Standby Diesel Generator start/load) during normal operation and during surveillance testing, STP is submitting this as an exigent request to limit the time operating in a configuration with one Train A LOP channel in trip. STPNOC requests approval of the proposed amendment by January 10, 2007 to allow corrective maintenance to be scheduled and performed before the next scheduled LOP instrument channel surveillance.

Exigent approval of the proposed TS change is justified because the failure that caused the inoperable channel could not reasonably have been anticipated. In addition, STPNOC has included the LOP instrumentation in its broad-scope risk-managed TS application, which will be the permanent TS resolution.

06002101 (Exigent Unit I LOP).doc STI: 32104070

NOC-AE-06002101 Page 2 There are no commitments in this submittal.

The STPNOC Plant Operations Review Committee has reviewed and concurred with the proposed change to the Technical Specifications.

In accordance with 10 CFR 50.91(b), STPNOC is notifying the State ofTexas of this request for license amendment by providing a copy of this letter and its attachments.

If there are any questions regarding the proposed amendment, please contact Mr. A. W. Harrison (361) 972-7298 or me at (361) 972-7849.

I declare under penalty 9f perjury that the foregoing is true and correct.

Executed on 4'ece,, ZkO ?06f Date E. D. Halpin Site Vice President and Plant General Manager awh/

Attachments:

1. Description of Changes and Safety Evaluation

2. Annotated Technical Specification Pages

3. Proposed Bases Inserts

NOC-AE-06002101 Page 3 cc:

(paper copy) (electronic copy)

Regional Administrator, Region TV A. H. Gutterman, Esquire U. S. Nuclear Regulatory Commission Morgan, Lewis & Bockius LLP 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 Mohan C. Thadani U. S. Nuclear Regulatory Commission Senior Resident Inspector Steve Winn U. S. Nuclear Regulatory Commission Christine Jacobs P. O. Box 289, Mail Code: MN16 Eddy Daniels Wadsworth, TX 77483 Marty Ryan Harry Holloway NRG South Texas LP C. M. Canady J. J. Nesrsta City of Austin R. K. Temple Electric Utility Department Kevin Pollo 721 Barton Springs Road Ed Alarcon Austin, TX 78704 City Public Service Richard A. Ratliff Jon C. Wood Bureau of Radiation Control Cox Smith Matthews Texas Department of State Health Services 1100 West 49th Street C. Kirksey Austin, TX 78756-3189 City of Austin

NOC-AE-06002101 Attachment 1 ATTACHMENT 1 DESCRIPTION OF CHANGES AND SAFETY EVALUATION NOC-AE-06002101 Page 1 1.0 Introduction Changes to the discussion in the December 20, 2006 submittal are denoted by change bars in the margin.

One channel of STP Unit 1 Loss of Power (LOP) instrumentation is currently inoperable and in the tripped condition per TS action requirements. Corrective maintenance will require a second channel to be made inoperable and STP TS have no action for two inoperable channels. Consequently TS 3.0.3 would apply. Because of the increased exposure to a potential inadvertent ESF actuation (ESF bus strip and Standby Diesel Generator start/load), STP is submitting this as an exigent request to limit the time operating in a configuration with one Train A LOP channel in trip. STPNOC requests approval of the proposed amendment by January 10, 2007 to facilitate early resolution of the Unit 1 condition.

STPNOC is proposing this amendment as a one-time change. A permanent change to the LOP instrumentation action statement is included in STPNOC's proposed risk-managed TS amendment.

2.0 Description TS 3.3.2, Table 3.3-3 ACTION 20 applies to the loss of power instrumentation. Since the loss of power instrumentation channels do not have an installed bypass capability, ACTION 20.b is the pertinent requirement:

ACTION 20 - With the number of OPERABLE channels one less than the Total Number of Channels, STARTUP and/or POWER OPERATION may proceed provided the following conditions are satisfied:

a. For Functional Units with installed bypass test capability, the inoperable channel may be placed in bypass, and must be placed in the tripped condition within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

Note: A channel may be bypassed for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for surveillance testing per Specification 4.3.2.1, provided no more than one channel is in bypass at any time.

b. For Functional Units with no installed bypass test capability,

1. The inoperable channel is placed in the tripped condition within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, and

2. The Minimum Channels OPERABLE requirement is met; however, the inoperable channel may be bypassed for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for surveillance testing of other channels per Specification 4.3.2.1.

Attachment I NOC-AE-06002101 Page 2 STPNOC proposes to add a note to ACTION 20 to establish a one-time provision for corrective maintenance on the Unit 1 Train A channel of LOP instrumentation. The note is based on the requirements in the Westinghouse Standard Technical Specifications (NUJREG-1431 Rev. 3). The note would read:

For Unit 1 Train A Loss of Power Instrumentation (Functional Unit 8.a, 8.b, &

8.c) only: In addition to the requirements of ACTION 20.b, the provision below shall apply. This provision shall expire 30 days after approval of the amendment.

With the number of OPERABLE channels more than one less than the Total Number of Channels, within one hour restore all but one channel per bus to OPERABLE status or enter applicable ACTION for the associated standby diesel generator made inoperable by the Loss of Power instrumentation.

3.0 Background and Justification for Exigent Change On December 1, 2006, STP Unit 1 Train A sequencer received a strip signal from one of four channels of undervoltage and degraded voltage relays for the Train 4.16KV bus.

Sequencer actuation is a 2/4 logic. No signal was received from any of the other three channels, indicating the strip signal was not valid. STPNOC placed the inoperable channel in the trip condition, as required by the TS. Corrective maintenance was scheduled for December 7, 2006, with the plan being to replace fuses. Pre-job review of the activity caused the job to be rescheduled to December 14, 2006. On December 14, STPNOC maintenance found indications that the potential transformer (PT) had failed.

Replacement of the PT will take several hours and access to the PT will require the two channels of the Train A LOP instrumentation that share the same drawer to be removed from service (i.e., the inoperable channel and one other channel). Since there is no TS action for two inoperable channels of LOP instrumentation, the shutdown requirement of TS 3.0.3 would apply. Voluntary entry into TS 3.0.3 is permissible for short durations (less than an hour) and for reasons other than operational convenience. Although this entry would not be for operational convenience, it would be for substantially longer than one hour. In accordance with the reporting guidance in NUREG-1022, such an entry into TS 3.0.3 would result in a reportable condition per 10CFR50.73. To avoid this situation, STPNOC is proposing to amend the TS for LOP to permit corrective maintenance.

While the TS allow continued operation with one channel of LOP instrumentation in the trip condition, operation in the configuration for an extended time exposes the plant to an invalid ESF actuation (ESF bus strip and start and load of SDG1 1) should another channel fail.

This condition also results in an unusual burden on the normal testing for the relays and the associated Standby Diesel Generator (SDG). With the "A" ESF bus LOP instrumentation failed and in trip, STP Unit 1 does not have power to the relay that provides reverse power protection to SDG1 1 when it is paralleled to the grid for NOC-AE-06002101 Page 3 surveillance testing. To minimize the exposure to any reverse power condition while the channel is inoperable, STP is running SDG1 1 at full load for 60 minutes (T.S.

requirement) instead of the normal 210 minutes (vendor recommendation). This protective'relay does not affect the emergency function of the diesel to respond to any signal provided by the sequencer since it would not be paralleled to offsite power.

STPNOC also has to perform trip actuating device operational tests (TADOT) on the operable LOP instrument channels in compliance with TS surveillance requirements (SR). Performing the TADOTs requires the inoperable channel to be bypassed while the other channel is tested. Placing the inoperable channel in bypass and restoring the channel to the trip condition after testing have some potential for a human performance error that would result in an ESF actuation.

Both the undervoltage and degraded voltage functions are in the tripped condition. The proposed note applies to Functional Unit #8, which includes undervoltage and degraded voltage channels (Functional Units 8.a, 8.b, 8.c).

Exigent approval of the proposed TS change is justified because the failure that caused the inoperable channel could not reasonably have been anticipated. In addition, STPNOC has included the LOP instrumentation in its broad-scope risk-managed TS application, which will be the permanent TS resolution. STPNOC has promptly prepared and submitted this proposed amendment to the Unit 1 TS.

To minimize the time the channel is inoperable and reduce the potential for these unnecessary challenges to the SDG and other ESF equipment, STPNOC intends to restore the failed channel to service as early as practical and believes the potential challenges described above justify an exigent change to the TS. STPNOC requests NRC approval of the request by January 10, 2007 to allow corrective maintenance to be scheduled and performed before the next scheduled LOP instrument channel TADOT (grace period ends January 14, 2007).

4.0 Technical Analysis Two under-voltage sensing schemes are employed for each Class 1E 4.16 kV bus to provide two levels of under-voltage protection. The first scheme detects loss of voltage and the second scheme detects degraded voltage conditions on the bus. Voltage signals to each scheme are provided through four potential transformers connected to each bus.

Four solid-state type instantaneous under-voltage relays and four time delay relays are used for the first scheme (loss of voltage). The devices used for the second scheme (degraded voltage) include four solid-state type instantaneous under-voltage relays and two sets of four time delay relays. (Ref: UFSAR Section 8.3.1.1.4.6.3)

The OPERABILITY requirements for the Loss of Power 4.16 kV ESF under-voltage relays and the 4.16 kV ESF degraded voltage relays are found under functional unit 8 in Table 3.3-3 of TS 3.3.2. The Loss of Powver 4.16 kV ESF under-voltage relays and the 4.16 kV ESF degraded voltage relays are required for the ESF systems to automatically NOC-AE-06002101 Page 4 function in any accident in which the loss of offsite power is assumed in the safety analysis.

The design function of the Loss of Power 4.16 kV ESF under-voltage relays and the 4.16 kV ESF degraded voltage relays is to provide an input to the associated ESF load sequencer when an under-voltage or degraded voltage condition is sensed from the offsite power source. The normal logic for a loss of power ESF actuation is two of four channels actuating.

The TS allow continued operation with one inoperable loss of power instrumentation channel if the channel is placed in the tripped condition within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. There is no action in the TS if more than one channel is inoperable. The applicable TS for more than one inoperable channel would be TS 3.0.3, which is unduly restrictive. In addition, once the inoperable channel is placed in the tripped condition, there is no provision in the TS to re-enter the action to perform corrective maintenance.

The subject relays perform a support function for the sequencer to start and /or load its associated standby diesel generator (SDG1 1) for those events involving a loss of off-site power. The ultimate effect of losing the LOP instrumentation function is that the associated diesel generator cannot be automatically loaded on the bus and is therefore inoperable. Consequently, the required action for loss of function of the LOP instrumentation is to declare the associated SDG inoperable. This requirement provides adequate compensatory action to assure plant safety and is consistent with the requirements in NUREG-1431.

Although STPNOC expects that the corrective maintenance will be completed in a single evolution, the note is a modification of the action statement and may be entered more than once before the provision expires 30 days after its approval.

The TS action provides for restoration of both affected channels (the intended outcome) or permitting one inoperable channel to be left in the trip condition (consistent with current TS).

STPNOC is proposing this amendment as a temporary change because the broad-scope STP Risk Managed TS application will provide a permanent resolution when it is approved.

NOC-AE-06002101 Page 5 5.0 Regulatory Safety Analysis 5.1 No Significant Hazards Determination STPNOC has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10CFR50.92, "Issuance of amendment," as discussed below. This determination is unchanged from the December 20, 2006 submittal.

1) Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No.

The proposed change to add a note to ACTION 20 for a one-time change to allow corrective maintenance on the Unit 1 Train A loss of power instrumentation does not change the plant design basis, system configuration or operation, and does not add or affect any accident initiator.

Therefore, STPNOC concludes that there is no 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 accident previously evaluated?

Response: No.

The proposed change does not change the plant design basis, system configuration or operation, and does not add or affect any accident initiator.

Therefore, STPNOC concludes the proposed 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.

No actual plant equipment or accident analyses will be affected by the proposed change. Additionally, the proposed changes will not relax any criteria used to establish safety limits, will not relax any safety systems settings, and will not relax the bases for any limiting conditions of operation. Therefore, STPNOC concludes the proposed changes do not involve a significant reduction in the margin of safety.

Conclusion Based upon the analysis provided herein, the proposed amendments do not involve a significant hazards consideration.

NOC-AE-06002101 Page 6 5.2 Applicable Regulatory Requirements/Criteria The regulatory basis for Technical Specification 3.3.2, "Loss of Power Instrumentation,"

is to ensure that sufficient power will be available to supply the safety-related equipment required for: (1) the safe shutdown of the facility, and (2) the mitigation and control of accident conditions within the facility. The minimum specified independent and redundant A.C. and D.C. sources satisfy the requirements of General Design Criteria (GDC) 17 of Appendix A to 10CFR Part 50.

The South Texas design has met GDC 2 and 4 with respect to structures, systems, and components of the onsite A.C. and D.C. power system being capable of withstanding the effects of natural phenomena (such as earthquake, tornadoes, hurricanes, and floods),

missiles, and environmental conditions associated with normal operation and postulated accidents.

The South Texas design has met GDC 5 with respect to structures, systems, and components of the A.C. and D.C. onsite power system. The onsite power system and components associated with Units 1 and 2 are housed in physically separate seismic Category I structures and are not shared.

The South Texas design has met GDC 17 which requires that all redundant equipment and circuits are separated by physically locating them in separate areas, separating by distance in the same area, and/or providing barriers between them.

The South Texas design has met GDC 18 with respect to the onsite A. C. and D.C. power system. The onsite power system is designed to be testable during station operation as well as when the station is shut down.

Because the proposed changes do not alter the design basis, change the plant configuration or significantly change operation procedures, STP maintains compliance with all applicable regulatory requirements.

In conclusion, based on the considerations discussed above, (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 amendment will not be inimical to the common defense and security or to the health and safety of the public.

Attachment 1 NOC-AE-06002101 Page 7 6.0 Environmental Considerations 10 CFR 51.22(b) specifies the criteria for categorical exclusions from the requirements for a specific environmental assessment per 10 CFR 51.21. This amendment request meets the criteria specified in 10 CFR 51.22(c)(9). The specific criteria contained in this section are discussed below.

(i) the amendment involves no significant hazards consideration As demonstrated in the No Significant Hazards Consideration Determination, the requested license amendment does not involve any significant hazards consideration.

(ii) there is no significant change in the types or significant increase in the amounts of any effluents that may be released offsite The requested license amendment involves no change to the facility and does not involve any change in the manner of operation of any plant systems involving the generation, collection or processing of radioactive materials or other types of effluents. Therefore, no increase in the amounts of effluents or new types of effluents would be created.

(iii) there is no significant increase in individual or cumulative occupational radiation exposure The requested license amendment involves no change to the facility and will not increase the radiation dose resulting from the operation of any plant system. Furthermore, implementation of this proposed change will not involve work activities which could contribute to occupational radiation exposure. Therefore, there will be no increase in individual or cumulative occupational radiation exposure associated with this proposed change.

Based on the above it is concluded that there will be no impact on the environment resulting from this change. The change meets the criteria specified in 10 CFR 51.22 for a categorical exclusion from the requirements of 10 CFR 51.21 relative to specific environmental assessment by the Commission.

7.0 References

1. South Texas Project Updated Final Safety Analysis Report

2. Standard Technical Specifications, Westinghouse Plants (NUREG-1431, Rev. 3)

NOC-AE-06002101 Attachment 2 ATTACHMENT 2 PROPOSED TECHNICAL SPECIFICATION CHANGES

No Changes TABLE 3.3-3 (Continued)

© ENGINEERED SAFETY FEATURES ACTUATION SYSTEM INSTRUMENTATION MINIMUM APPLICABLE TOTAL NO. CHANNELS CHANNELS MODES FUNCTIONAL UNIT OF CHANNELS TO TRIP OPERABLE ACTION

8. Loss of Power

a. 4.16 kV ESF Bus Under- 4/bus 2/bus 3/bus 1,2,3,4 20 voltage-Loss of Voltage

b. 4.16 kV ESF Bus Under-voltage-Tolerable Degraded Voltage Coincident with SI 4/bus 2/bus 3/bus 1, 2, 3, 4 20

c. 4. 16 kV ESF Bus Under-voltage - Sustained Degraded Voltage 4/bus 2/bus 3/bus 1, 2, 3, 4 20

9. Engineered Safety Features Actuation System Interlocks

a. Pressurizer Pressure, P-11 3 2 2 1,2,3 21

b. Low-Low Tavg, P-12 4 2 3 1, 2, 3 21

c. Reactor Trip, P-4 2 1 2 1, 2, 3 23 R. -

r+

(D CD

TABLE 3.3-3 (Continued)

ACTION STATEMENTS (Continued)

2. With two less than the Minimum Channels OPERABLE requirement for RCB Purge Radioactivity-High, operation may continue provided the containment purge supply and exhaust valves are maintained closed.

c) MODE 6#: With less than the Minimum Channels OPERABLE requirement for RCB Purge Radioactivity - High, apply the requirements of Technical Specification 3.9.9 for an inoperable Containment Ventilation Isolation System.

NOTE:

With one less than the Minimum Channels Operable requirement for RCB Purge Radioactivity-High, Supplementary or Normal containment purge supply and isolation valves may be open for up to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> at a time for required purge operation provided the valves are under administrative control.

ACTION 19 - With the number of OPERABLE channels one less than the Minimum Channels OPERABLE requirement, restore the inoperable channel to OPERABLE status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

ACTION 20 - With the number of OPERABLE channels one less than the Total Number of Channels, STARTUP and/or POWER OPERATION may proceed provided the following conditions are satisfied:

a. For Functional Units with installed bypass test capability, the inoperable channel may be placed in bypass, and must be placed in the tripped condition within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

Note: A channel may be bypassed for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for surveillance testing per Specification 4.3.2.1, provided no more than one channel is in bypass at any time.

b. For Functional Units with no installed bypass test capability,

1. The inoperable channel is placed in the tripped condition within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, and

2. The Minimum Channels OPERABLE requirement is met; however, the inoperable channel may be bypassed for up to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for surveillance testing of other channels per Specification 4.3.2.1.

Fýor Unit 1Tra'in'A Loss o'f Power lnstrumientati,on(F-unctio 1naI Unit 8.a, 8. 1b, & 8.c) only: In addition to the requirements of ACTION 20.b, the provision below-shall apply. This provision

'shall ex~pire 30.days after approva! of the amendment.

With the number of O P ERABLE channels more than one less thanthe tTotal Number of channels, within one hour restore all but one channel per bus to OPERABLE status or enter applicable ACTION for the associated stanldby diesel generator made inoperable by the Loss of Power instrumentation.

ACTION 21 - With less than the Minimum Number of Channels OPERABLE, within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> determine by observation of the associated permissive annunciator window(s) that the interlock is in its required state for the existing plant condition, or apply Specification 3.0.3.

ACTION 22 - With the number of OPERABLE channels one less than the Minimum Channels OPERABLE requirement, restore the inoperable channel to OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in at least HOT SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />; however, one channel may be bypassed for up to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for surveillance testing per Specification 4.3.2.1 provided the other channel is OPERABLE.

ACTION 23 - With the number of OPERABLE channels one less than the Total Number of Channels, restore the inoperable channel to OPERABLE status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> or be in at least HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in at least HOT SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

SOUTH TEXAS - UNITS 1 & 2 3/4 3-27 Unit 1 - Amendment No. 24, , 36, 1,6 Unit 2 - Amendment No. 4-4, 1-2, 150

NOC-AE-06002101 Proposed Bases Inserts

LOP Instrumentation BASES insert for Unit 1 Train A (Functional Unit 8.a, 8.b, 8.c)

For Unit 1 Train A, a note is added to ACTION 20.b for a condition when more than one loss of voltage or more than one degraded voltage channel per bus are inoperable. The action in the note requires restoring all but one channel per bus to OPERABLE status. The 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> Completion Time should allow ample time to repair most failures and takes into account the low probability of an event requiring an LOP start occurring during this interval. If the channels are not restored in the 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> completion time, the Conditions specified in TS 3.8.1.1, "AC Sources

- Operating," for the DG made inoperable by failure of the LOP DG start instrumentation are required to be entered immediately. The actions of that LCO provides for adequate compensatory actions to assure unit safety. This note supports a one-time change to facilitate corrective maintenance and expires 30 days after approval of the license amendment that added it.