ML110750416

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Licensee Slides from 3/15/11 Meeting with Entergy Operations on Technical Specification Change - Testing of Idle RCS Cooling Loop
ML110750416
Person / Time
Site: Arkansas Nuclear Entergy icon.png
Issue date: 03/15/2011
From: David Bice
Entergy Operations
To:
Plant Licensing Branch IV
Kalyanam N, NRR/DLPM, 415-1480
References
TAC ME4563
Download: ML110750416 (16)
v • d • e


Text

RCS Cooling Loop Testing Allowance RCS Cooling Loop Testing Allowance 1

INTRODUCTION INTRODUCTION

  • On August 24, 2010, Entergy submitted proposed On August 24, 2010, Entergy submitted proposed Technical Specification (TS) change extending the Technical Specification (TS) change extending the allowed time in which one required Reactor allowed time in which one required Reactor Coolant System (RCS) cooling loop may be Coolant System (RCS) cooling loop may be RCS Cooling Loop Testing Allowance RCS Cooling Loop Testing Allowance Coolant System (RCS) cooling loop may be Coolant System (RCS) cooling loop may be removed from service for testing (Modes 5 and removed from service for testing (Modes 5 and 6--low water level) low water level)
  • The proposal also revised the Mode 4 The proposal also revised the Mode 4 requirements for one inoperable loop to be requirements for one inoperable loop to be consistent with other TS requirements consistent with other TS requirements
  • Entergy provided additional information in letters Entergy provided additional information in letters dated November 12, 2010, and February 28, 2011 dated November 12, 2010, and February 28, 2011 2

PURPOSE PURPOSE RCS Cooling Loop Testing Allowance RCS Cooling Loop Testing Allowance Discuss the proposed changes, Discuss the proposed changes, understand the Staffs concerns, and understand the Staffs concerns, and 3

identify areas for improvement identify areas for improvement

BACKGROUND BACKGROUND -- MODE 4 (200 MODE 4 (200 -- 280 280 °°F)

F)

Reactor Coolant System (RCS) cooling loop:

RCS Cooling Loop Testing Allowance RCS Cooling Loop Testing Allowance 3/4 48 48--hour Completion Time requested consistent with hour Completion Time requested consistent with the same pump Low Pressure Injection (LPI) TS the same pump Low Pressure Injection (LPI) TS 4

3/4 The 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> is conservative with respect to the The 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> is conservative with respect to the Mode 3 RCS Cooling Loops Completion Time of Mode 3 RCS Cooling Loops Completion Time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> 72 hours 3/4 In Mode 4, Decay Heat Removal (DHR) loops and/or In Mode 4, Decay Heat Removal (DHR) loops and/or cooling via Steam Generators (SGs) are available, cooling via Steam Generators (SGs) are available, dependent on RCS pressure dependent on RCS pressure 3/4 The current take immediate action requirement The current take immediate action requirement came from NRC letter dated June 11, 1980, due to came from NRC letter dated June 11, 1980, due to inadequate administrative controls associated inadequate administrative controls associated with DHR systems, and was applicable to all plants.

with DHR systems, and was applicable to all plants.

TECHNICAL INFORMATION TECHNICAL INFORMATION -- MODE 4 MODE 4

  • The August 24, 2010, submittal provided the basis The August 24, 2010, submittal provided the basis for permitting a 48 for permitting a 48--hour out hour out--of of--service period for service period for one required cooling loop one required cooling loop RCS Cooling Loop Testing Allowance RCS Cooling Loop Testing Allowance
  • The basis focused on the multiple cooling sources The basis focused on the multiple cooling sources available in this mode and the lower operating available in this mode and the lower operating temperatures/pressures when compared to temperatures/pressures when compared to Mode 3, which contains a 72 Mode 3, which contains a 72--hour out hour out--of of--service service allowance for one loop allowance for one loop

QUESTIONS QUESTIONS MODE 4 MODE 4 RCS Cooling Loop Testing Allowance RCS Cooling Loop Testing Allowance QUESTIONS QUESTIONS -- MODE 4 MODE 4 6

BACKGROUND BACKGROUND -- MODES 5 & 6 MODES 5 & 6 RCS Cooling Loop Testing Allowance RCS Cooling Loop Testing Allowance

  • In Modes 5, and Mode 6 with low water level, the In Modes 5, and Mode 6 with low water level, the proposed change extends the current 2 proposed change extends the current 2--hour allowance hour allowance for testing of one cooling loop to up to 8 for testing of one cooling loop to up to 8--hours, with hours, with restriction restriction 7
  • Proposed TS Note:

Proposed TS Note:

3/4 One required DHR loop may be inoperable for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> One required DHR loop may be inoperable for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> for surveillance testing provided that the other DHR loop for surveillance testing provided that the other DHR loop is OPERABLE and in operation.

is OPERABLE and in operation.

  • Current TS Note:

Current TS Note:

3/4 One required DHR loop may be inoperable for One required DHR loop may be inoperable for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> for hours for surveillance testing provided that the other DHR loop is surveillance testing provided that the other DHR loop is OPERABLE and in operation OPERABLE and in operation, and the inoperable DHR loop

, and the inoperable DHR loop can be restored to OPERABLE status within the calculated can be restored to OPERABLE status within the calculated time time--to to--boil period boil period.

BACKGROUND BACKGROUND

  • The only restriction for the current 2 The only restriction for the current 2--hour hour allowance is that the remaining cooling loop allowance is that the remaining cooling loop is operable and in operation is operable and in operation RCS Cooling Loop Testing Allowance RCS Cooling Loop Testing Allowance
  • To ensure margin to safety is maintained, To ensure margin to safety is maintained, Entergy proposed an additional restriction Entergy proposed an additional restriction related to the core time related to the core time--to to--boil (TTB) boil (TTB)
  • Entergy proposed to extend this allowance Entergy proposed to extend this allowance to up to 8 to up to 8--hours in support of non hours in support of non--intrusive intrusive testing, such as the Degraded Voltage testing, such as the Degraded Voltage Monitoring Integrated Test Monitoring Integrated Test 8

TECHNICAL INFORMATION TECHNICAL INFORMATION -- MODE 5 MODE 5

  • The August 24, 2010, submittal provided the basis The August 24, 2010, submittal provided the basis for permitting one required cooling loop to be for permitting one required cooling loop to be removed from service for testing for up to 8 removed from service for testing for up to 8--hours hours RCS Cooling Loop Testing Allowance RCS Cooling Loop Testing Allowance
  • The basis focused on the low energy of the RCS The basis focused on the low energy of the RCS fluid in this mode and the multiple administrative fluid in this mode and the multiple administrative controls related to protection of the operating controls related to protection of the operating cooling loop, availability of SGs via forced or cooling loop, availability of SGs via forced or natural circulation cooling, and available RCS natural circulation cooling, and available RCS makeup sources makeup sources
  • An additional margin to safety is ensured beyond An additional margin to safety is ensured beyond that currently required by the TSs (TTB) that currently required by the TSs (TTB) 9

TECHNICAL INFORMATION TECHNICAL INFORMATION -- MODE 6 MODE 6

  • The August 24, 2010, submittal provided the basis The August 24, 2010, submittal provided the basis for permitting one required cooling loop to be for permitting one required cooling loop to be removed from service for testing for up to 8 removed from service for testing for up to 8--hours hours RCS Cooling Loop Testing Allowance RCS Cooling Loop Testing Allowance
  • The basis focused on the multiple administrative The basis focused on the multiple administrative controls related to protection of the operating controls related to protection of the operating cooling loop (similar to Mode 5), the amount of cooling loop (similar to Mode 5), the amount of water in the refueling canal, and available RCS water in the refueling canal, and available RCS makeup sources makeup sources
  • By proposing the new TTB restriction, an By proposing the new TTB restriction, an additional margin to safety is ensured beyond that additional margin to safety is ensured beyond that currently required by the TSs currently required by the TSs 10
  • A discussion of proceduralized administrative controls A discussion of proceduralized administrative controls related to GL 88 related to GL 88--17, as generically discussed in the 17, as generically discussed in the original submittal original submittal RCS Cooling Loop Testing Allowance RCS Cooling Loop Testing Allowance The November 12, 2010, submittal provided The November 12, 2010, submittal provided additional information as follows:

additional information as follows:

original submittal original submittal

  • Further discussion of core cooling methods and related Further discussion of core cooling methods and related procedure controls was provided procedure controls was provided
  • Information of the TTB calculation, with discussion of Information of the TTB calculation, with discussion of different plant configurations and effects on TTB different plant configurations and effects on TTB 11
  • A discussion of the rare condition when no cooling loop may be A discussion of the rare condition when no cooling loop may be available, including a historical search of loss of cooling events available, including a historical search of loss of cooling events
  • Further discussion of procedural controls for SG nozzle dams Further discussion of procedural controls for SG nozzle dams RCS Cooling Loop Testing Allowance RCS Cooling Loop Testing Allowance The February 28, 2011, submittal provided The February 28, 2011, submittal provided additional information as follows:

additional information as follows:

  • Further procedure discussion geared toward operator capability Further procedure discussion geared toward operator capability and TTB and time and TTB and time--to to--core core--uncovery (TTCU) examples uncovery (TTCU) examples
  • Further discussion of the TTB estimate and assumptions, Further discussion of the TTB estimate and assumptions, specifically addressing thermohydraulic mixing of the refueling specifically addressing thermohydraulic mixing of the refueling canal water canal water
  • Instrumentation requirements (consistent with that required by Instrumentation requirements (consistent with that required by GL 88 GL 88--17) 17)
  • Discussion of effects of upper reactor vessel internals on Discussion of effects of upper reactor vessel internals on natural convection cooling natural convection cooling 12
  • Further information related to required testing for Further information related to required testing for RCS Cooling Loop Testing Allowance RCS Cooling Loop Testing Allowance Future information to be provided is as Future information to be provided is as summarized below:

summarized below:

Further information related to required testing for Further information related to required testing for which the 8 which the 8--hour allowance supports hour allowance supports

  • Further examples of TTB estimates and the Further examples of TTB estimates and the assumptions (parameters) assumed in these examples assumptions (parameters) assumed in these examples 13

In summary, the idle cooling loop would no longer In summary, the idle cooling loop would no longer be removed from service for testing without be removed from service for testing without verifying that the loop can be returned to service verifying that the loop can be returned to service within the estimated TTB.

within the estimated TTB.

This requirement places an additional restriction This requirement places an additional restriction RCS Cooling Loop Testing Allowance RCS Cooling Loop Testing Allowance This requirement places an additional restriction This requirement places an additional restriction on the current 2 on the current 2--hour allowance and maintains a hour allowance and maintains a reasonable margin to safety for testing activities reasonable margin to safety for testing activities during this period.

during this period.

14

CONCLUSION CONCLUSION RCS Cooling Loop Testing Allowance RCS Cooling Loop Testing Allowance ANO ANO--1 meets the requirements of GL 88 1 meets the requirements of GL 88--17 and 17 and has substantial defense has substantial defense--in in--depth strategies to depth strategies to prevent a loss of DHR event. This includes prevent a loss of DHR event. This includes 15 p

necessary systems, components, and necessary systems, components, and instrumentation to permit identification of a instrumentation to permit identification of a potential loss of DHR and minimize the potential loss of DHR and minimize the consequences should a loss of DHR occur.

consequences should a loss of DHR occur.

Significant deterministic technical information has Significant deterministic technical information has been provided to establish a reasonable margin to been provided to establish a reasonable margin to safety when testing an idle cooling loop.

safety when testing an idle cooling loop.

QUESTIONS QUESTIONS MODES 5/6 MODES 5/6 RCS Cooling Loop Testing Allowance RCS Cooling Loop Testing Allowance QUESTIONS QUESTIONS -- MODES 5/6 MODES 5/6 16

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