ML14224A645

Arkansas Nuclear One, Unit 2 - Response to Request for Additional Information, Adoption of Technical Specification Task Force (TSTF)-500, Revision 2 DC Electrical Rewrite - Update to TSTF-360

ML14224A645
Person / Time
Site:	Arkansas Nuclear
Issue date:	08/12/2014
From:	Browning J G Entergy Operations
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
2CAN081402, TAC MF0595
Download: ML14224A645 (13)

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2CAN081402

August 12, 2014 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 SUBJECT: Response to Request for Additional Information Adoption of Technical Specification Task Force (TSTF)-500, Revision 2 "DC Electrical Rewrite - Update to TSTF-360" Arkansas Nuclear One, Unit 2 Docket No. 50-368 License No. NPF-6

Dear Sir or Madam:

By letter dated January 28, 2013 (Reference 1), Entergy Operations, Inc. (Entergy) requested adoption of Technical Specification Task Force (TSTF)-500, Revision 2, for Arkansas Nuclear One, Unit 2 (ANO-2). References 2 and 3 are associated with an NRC Request for Additional Information (RAI) and Entergy's response to the RAI. By letter dated August 4, 2014, the NRC issued an follow-up RAI (Reference 4). Attachment 1 of this letter contains the associated Entergy response to this second RAI. The Entergy response requires a change to one or more Technical Specifications previously submitted in the Reference 1 letter. Attachment 2 of this letter contains new TS markup pages, where necessary to support the RAI response, and

Attachment

3 contains revised (clean) TS pages in this regard. The pages included in the attachments to this letter supersede those that may have previously been submitted in the

Reference

1 and 3 submittals. The responses and new TS pages have no impact on the acceptability of TSTF-500 adoption for ANO-2 and have no impact on the no significant hazards consideration included in the

Reference

2 letter.

In accordance with 10 CFR 50.91(b)(1), a copy of this application and the reasoned analysis about no significant hazards consideration is being provided to the designated Arkansas state official.

No new commitments have been identified in this letter.

If you have any questions or require additional information, please contact Stephenie Pyle at 479-858-4704.

Entergy Operations, Inc. 1448 S.R. 333 Russellville, AR 72802 Tel 479-858-3110 Jeremy G. Browning Vice President - Operations Arkansas Nuclear One 2CAN081402 Page 2 of 3 I declare under penalty of perjury that the foregoing is true and correct.

Executed on August 12, 2014.

Sincerely, ORIGINAL SIGNED BY JEREMY G. BROWNING JGB/dbb

REFERENCES:

1. Entergy letter dated January 28, 2013, License Amendment Request - Adoption of Technical Specification Task Force (TSTF)-500, Revision 2, "DC Electrical Rewrite - Update to TSTF-360" (2CAN011301) (TAC No. MF0595) (ML13029A770) 2. NRC email dated August 6, 2013, Arkansas Nuclear One, Unit 2 - Request for Additional Information Regarding License Amendment Request for Adoption of Technical Specifications Task Force (TSTF)

Traveler TSTF-500, Revision 2, DC Electrical Rewrite - Update to TSTF-360 (ML13218A227) 3. Entergy letter dated September 16, 2013, Response to Request for Additional Information - Adoption of Technical Specification Task Force (TSTF)-500, Revision 2, "DC Electrical Rewrite - Update to TSTF-360" (2CAN091301) (ML13261A353) 4. NRC email dated August 4, 2014, Arkansas Nuclear One, Unit 2 - Request for Additional Information Regarding License Amendment Request Proposing Adoption of Technical Specifications Task Force Traveler TSTF-500 (ML14210A521)

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1. Response to Request for Additional Information - ANO-2 Adoption of TSTF-500 2. Replacement Technical Specification and Bases Changes (mark-up) 3. Replacement Revised (clean) Technical Specification Pages 2CAN081402 Page 3 of 3 cc: Mr. Marc L. Dapas Regional Administrator U. S. Nuclear Regulatory Commission Region IV 1600 East Lamar Boulevard Arlington, TX 76011-4511 NRC Senior Resident Inspector Arkansas Nuclear One P. O. Box 310 London, AR 72847 U. S. Nuclear Regulatory Commission Attn: Ms. Andrea E. George MS O-8B1 One White Flint North 11555 Rockville Pike Rockville, MD 20852 Mr. Bernard R. Bevill Arkansas Department of Health Radiation Control Section 4815 West Markham Street Slot #30 Little Rock, AR 72205 Attachment 1 to 2CAN081402 Response to Request for Additional Information ANO-2 Adoption of TSTF-500

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1 to 2CAN081402 Page 1 of 4 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION ANO-2 Adoption of TSTF-500 By letter dated August 4, 2014 (Reference 4), the NRC requested additional information associated with Entergy Operations, Inc. (Entergy's) request to amend the Arkansas Nuclear One, Unit 2 (ANO-2) Technical Specifications (TS) consistent with Technical Specification Task Force (TSTF) Traveler TSTF-500, Revision 2 (Reference 1). Questions provided by the NRC in the subject email are included below, followed by the respective Entergy response.

1. In the supplement dated September 16, 2014, in response to NRC questions E3.a and E9.b, the licensee proposed to adopt TSTF-500, LCO 3.8.5, Required Action A.2, which verifies float current is returned to 2 amps within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The 12-hour completion time (CT) is bracketed in TSTF-500. The TS Bases pages submitted with the application provide a general discussion of the rationale for the proposed CT, but do not have sufficient detail for the NRC staff to complete its review of this plant specific value. Please provide a more detailed basis for the proposed 12-hour CT for ANO-2. This response should include a calculation, or calculation summary, specific to the ANO-2 batteries. Response The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. Total normal steady state loads on the battery chargers average less than 130 amps (A) based on monthly walk down data. Each battery charger is rated for 400 A. Conservatively assuming the charger output is only 300 amps maximum based on proposed battery charger testing: 300 A available - 130 A steady state load = 170 A excess capacity for battery charging. Assuming the battery charger is offline for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> (the time allowed by TSTF-500 to place a charger on the battery) and assuming normal steady state DC system loads remain on battery during this time would equate to a 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> x 130 A (or 260 A-hour) loss. Assuming 110% of 260 A-hour (or 286 A-hour) would be required to restore the battery to a fully recharged state and given the 170 A excess battery charger capacity above, the battery can be restored to fully recharged within 286 A-hour / 170 A = 1.7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />. However, because the battery chargers are constant voltage chargers rather than constant current chargers, it is recognized that the battery charging current will taper off from the initial maximum current that the charger can supply to a final value of < 2 amps. ANO does not possess battery recharge current characteristic curves, but it is considered reasonable to expect that the battery would be fully recharged in < 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to < 2 amps charging current given the above charger capacity and relatively small amount of capacity removed from the batteries.

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1 to 2CAN081402 Page 2 of 4 2. In the supplement dated September 16, 2014, in response to NRC question E4, the licensee stated that it is inappropriate to combine Actions "a" and "b" since the response to an inoperable battery charger differs from that of an inoperable battery. However, the NRC staff's question E4 related to the justification for not combining Actions "b" and "c" (inoperable battery bank and inoperable DC electrical power subsystem, respectively). In the licensee's proposed TSs, the CTs for an inoperable battery bank and an inoperable DC subsystem have the same value of 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. In TSTF-500, Action "b" is deleted and only Action "c" is used if these two Actions have the same CT. Therefore please provide a justification for the deviation from TSTF-500 or, alternatively, provide an updated TS page which is consistent with TSTF-500. Response The Action associated with an inoperable battery bank was originally maintained for consistency with the current ANO-2 TSs, although redundant to new Action 'c'. Entergy has determined that removal of this redundant Action is appropriate and consistent with TSTF-500. A revised markup of the associated TS and TS Bases page is included in

Attachment

2 of this letter. A revised (clean) TS page is included in Attachment 3 of this letter. Entergy requests that the previous like-pages submitted be replaced with those attached to this letter.

3. In Attachment 1 to the submittal dated January 28, 2013, Section 2.2, the licensee proposed to relocate the battery connection resistance limit to the Battery Monitoring and Maintenance Program, a) Please clarify whether the specified value of 50 micro-ohms is the resistance limit per connection (i.e., inter-cell connection, each inter-rack connection, each inter-tier connection, and terminal connection). b) Please provide the basis for the specified connection resistance value. Response - Part 3.a The 50 micro-ohm (µohm) limit is the resistance limit for any one inter-cell connection, inter-tier (or inter-rack) connection, or terminal cable connection. ANO-2 batteries (C&D LCR-31) have two posts per pole, identified in the battery procedure as P1 & P2 and N1 & N2. For these two-post cells, two resistance measurements are taken for each inter-cell resistance measurement, i.e. P1 to N1 and P2 to N2, in accordance with IEEE Std. 450-2002, Annex F. Although the connections are essentially in parallel, if either of these measurements exceeds the 50 micro-ohms maintenance limit, then actions are taken to correct the condition. Battery terminal cable connections and interior cable connections are treated in the same manner.

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1 to 2CAN081402 Page 3 of 4 Response - Part 3.b As discussed in Attachment 1, Page 9, of the original amendment request (Reference 1),

ANO-2 DC voltage drop calculations indicate that minimum DC voltage is maintained for all required loads assuming a resistance of 50 µohms per each inter-cell, inter-tier (inter-rack), and terminal connection. The current proceduralized battery maintenance limit is, therefore, 50 µohms on a per-connection basis, which significantly minimizes potential impact to overall battery performance (i.e., maintenance is not delayed to the point where many cells might indicate resistance values greater than that assumed in the calculations). Any connection reaching the maintenance limit of 50 µohms also requires initiation of a Condition Report to evaluate operability impacts on the battery bank.

4. In Attachment 4 to the submittal dated January 28, 2013, the licensee proposed a battery cell float voltage limit of greater than or equal to 2.07 volts (V) which is reflected in new TS 3.8.3 Action a.ii, SR 4.8.3.2, and SR 4.8.3.5. This 2.07 V is bracketed in TSTF-500. In Attachment 1 to the submittal dated January 28, 2013, the licensee stated that the requirements of the new adopted SRs 4.8.3.2 through 4.8.3.5 are similar to requirements currently contained in existing TS Table 4.8-2, "Battery Cell Surveillance Requirements." The Category B float voltage allowable value for each connected cell in Table 4.8-2 is > 2.07 V. Please explain the change from > 2.07 V to 2.07 V, as well as the basis for the 2.07 V cell float voltage limit. Response The ANO-2 battery cells (C&D Model LCR-31) are of the vented lead-acid type with a nominal electrolyte specific gravity of 1.215. Open circuit voltage of the lead-acid battery cell is related to the specific gravity by a constant as shown in the following equation (reference EPRI TR-100248 Rev. 2): Open Circuit Voltage = Specific Gravity + 0.845 Therefore, for the ANO-2 battery cells, the nominal cell open circuit voltage is 1.215 + 0.845

= 2.06 volts DC. A cell voltage of less than or equal to cell open circuit voltage indicates the cell is no longer being floated at a voltage sufficient to prevent discharge. The battery cell float voltage limit change from > 2.07 V to 2.07 V is proposed for consistency with TSTF-500 and, subsequently, the improved standard TSs. Because the actual open circuit cell voltage provided by the battery manufacturer is 2.063 V, the change from > 2.07 V to 2.07 V as the allowable limit is acceptable.

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1 to 2CAN081402 Page 4 of 4 REFERENCES:

1. Entergy letter dated January 28, 2013, License Amendment Request - Adoption of Technical Specification Task Force (TSTF)-500, Revision 2, "DC Electrical Rewrite - Update to TSTF-360" (2CAN011301) (TAC No. MF0595) (ML13029A770)

2. NRC email dated August 6, 2013, Arkansas Nuclear One, Unit 2 - Request for Additional Information Regarding License Amendment Request for Adoption of Technical Specifications Task Force (TSTF) Traveler TSTF-500, Revision 2, DC Electrical Rewrite - Update to TSTF-360 (TAC No. MF0595) (ML13218A227)

3. Entergy letter dated September 16, 2013, Response to Request for Additional Information - Adoption of Technical Specification Task Force (TSTF)-500, Revision 2, "DC Electrical Rewrite - Update to TSTF-360" (2CAN091301) (ML13261A353) 4. NRC email dated August 4, 2014, Arkansas Nuclear One, Unit 2 - Request for Additional Information Regarding License Amendment Request Proposing Adoption of Technical Specifications Task Force Traveler TSTF-500 (ML14210A521)

Attachment 2 to 2CAN081402 Replacement Technical Specification and Bases Changes (mark-up)

ARKANSAS - UNIT 2 3/4 8-8 Amendment No. 54,75,94, ELECTRICAL POWER SYSTEMS D.C. SOURCESDISTRIBUTION - OPERATING LIMITING CONDITION FOR OPERATION 3.8.2.3 As a minimum, Tthe Train A and Train Bfollowing D.C. electrical power subsystemssources shall be OPERABLE.: TRAIN "A" consisting of 125-volt D.C. bus No. 1, 125-volt D.C. battery bank No. 1 and a full capacity charger. TRAIN "B" consisting of 125-volt D.C. bus No. 2, 125-volt D.C. battery bank No. 2 and a full capacity charger. APPLICABILITY: MODES 1, 2, 3 and 4.

ACTION: ba. With one DC electrical power subsystemof the required battery banks inoperable for reasons other than ACTION 'a' above, restore the inoperable DC electrical power subsystembattery bank to OPERABLE status within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 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 />. ab. With one of the required full capacity chargers inoperable:, i. Restore the battery terminal voltage to greater than or equal to the minimum established float voltagedemonstrate the OPERABILITY of its associated battery bank by performing Surveillance Requirement 4.8.2.3.a.1 within 2one hours and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter. If any Category A limit in Table 4.8-2 is not met, declare the battery inoperable, and ii. Verify battery float current 2 amps once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Otherwise, 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 />. SURVEILLANCE REQUIREMENTS 4.8.2.3.1 Each 125-volt battery bank and charger shall be demonstrated OPERABLE: a. At least once per 7 days by verifying that: 1. The parameters in Table 4.8-2 meet the Category A LIMITS, and 2. tThe total battery terminal voltage is greater than or equal to the minimum established float voltage129 volts on float charge for a 60 cell battery bank and greater than or equal to 124.7 volts on float charge for a 58 cell battery bank. b. At least once per 92 days and within 7 days after a battery discharge with battery terminal voltage below 110 volts, or battery overcharge with battery terminal voltage above 150 volts, by verifying that: 1. The parameters in Table 4.8-2 meet the Category B LIMITS, ARKANSAS - UNIT 2 B 3/4 8-9 Rev. 3/4.8 ELECTRICAL POWER SYSTEMS BASES If the charger is operating in the current limit mode after 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, that is an indication that the battery is partially discharged and its capacity margins will be reduced. The time to return the battery to its fully charged condition in this case is a function of the battery charger capacity, the amount of loads on the associated DC system, the amount of the previous discharge, and the recharge characteristic of the battery. The charge time can be extensive, and there is not adequate assurance that it can be recharged within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> (ACTION "a.ii"). ACTION "a.ii" requires that the battery float current be verified as less than or equal to 2 amps. This indicates that, if the battery had been discharged as the result of the inoperable battery charger, it is now fully capable of supplying the maximum expected load requirement. The 2-amp value is based on returning the battery to 98% charge and assumes a 2% design margin for the battery. If at the expiration of the initial 12-hour period the battery float current is not less than or equal to 2 amps, this indicates there may be additional battery problems and the battery must be declared inoperable. ACTION "b" represents one subsystem with a loss of ability to completely respond to an event, and a potential loss of ability to remain energized during normal operation. It is therefore, imperative that the operator's attention focus on stabilizing the unit, minimizing the potential for complete loss of DC power to the affected subsystem. The 2-hour limit is consistent with the allowed time for an inoperable DC distribution subsystem. If one of the required DC electrical power subsystems is inoperable for reasons other than ACTION "a" (e.g., inoperable battery charger), the remaining DC electrical power subsystem has the capacity to support a safe shutdown and to mitigate an accident condition. Since a subsequent worst case single failure could, however, result in the loss of the minimum necessary DC electrical subsystems to mitigate a worst case accident, continued power operation should not exceed 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. The 2-hour AOT is based on Regulatory Guide (RG) 1.93 and reflects a reasonable time to assess unit status as a function of the inoperable DC electrical power subsystem and, if the DC electrical power subsystem is not restored to OPERABLE status, to prepare to effect an orderly and safe unit shutdown. If the inoperable DC electrical power subsystem cannot be restored to OPERABLE status within the required AOT, the unit must be brought to a MODE in which the LCO does not apply. To achieve this status, the unit must be brought to at least MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and to MODE 5 within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. The AOTs are reasonable, based on operating experience, to reach the required unit conditions from full power conditions in an orderly manner and without challenging plant systems. The AOT to bring the unit to MODE 5 is consistent with the time required in RG 1.93.

Attachment 3 to 2CAN081402 Replacement Revised (clean) Technical Specification Pages ARKANSAS - UNIT 2 3/4 8-8 Amendment No. 54,75,94, ELECTRICAL POWER SYSTEMS DC SOURCES - OPERATING LIMITING CONDITION FOR OPERATION 3.8.2.3 The Train A and Train B DC electrical power subsystems shall be OPERABLE. APPLICABILITY: MODES 1, 2, 3 and 4. ACTION: a. With one of the required full capacity chargers inoperable: i. Restore the battery terminal voltage to greater than or equal to the minimum established float voltage within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, and ii. Verify battery float current 2 amps once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. b. With one DC electrical power subsystem inoperable for reasons other than ACTION 'a' above, restore the inoperable DC electrical power subsystem to OPERABLE status within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. Otherwise, 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 />. SURVEILLANCE REQUIREMENTS 4.8.2.3.1 At least once per 7 days by verifying that the battery terminal voltage is greater than or equal to the minimum established float voltage.