NRC 2009-0099, Response to Request for Additional Information Regarding Generic Letter 2008-01 Managing Gas Accumulation in Emergency Core Cooling. Decay Heat Removal and Containment Spray Systems

Response to Request for Additional Information Regarding Generic Letter 2008-01 Managing Gas Accumulation in Emergency Core Cooling. Decay Heat Removal and Containment Spray Systems

ML093000085
Person / Time
Site:	Point Beach
Issue date:	10/24/2009
From:	Meyer L Point Beach
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GL-08-001, NRC 2009-0099, TAC MD7864, TAC MD7865
Download: ML093000085 (8)

Text

NEXTera TM POINT BEACH October 24,2009 NRC 2009-0099 10 CFR 50.54(f)

U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Point Beach Nuclear Plant, Units Iand 2 Dockets 50-266 and 50-301 Renewed License Nos. DPR-24 and DPR-27 Response to Reauest for Additional lnformation Regarding Generic Letter 2008-01 Managing Gas Accumulation in Emergencv Core Coolina. Decav Heat Removal and Containment Sprav Svstems

References:

(1) Point Beach, Units 1 and 2, Nine-Month Response to NRC Generic Letter 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems, dated October 14,2008.

(ML082880659)

(2) Point Beach, Unit 1, Nine-Month Supplemental (Post-Outage) Response to NRC Generic Letter 2008-01, dated February 11,2009. (ML090420473)

(3) Point Beach Nuclear Plant, Units 1 and 2 - Request for Additional lnformation Re: Response to Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems" (TAC Nos. MD7864 and MD7865), dated September 25,2009. (ML092650687)

The Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems, on January 1I, 2008. NextEra Energy Point Beach, LLC (NextEra) responded to GL 2008-01 for Point Beach Nuclear Plant (PBNP) Units 1 and 2, via References ( I ) and (2). The NRC requested additional information (RAI) in Reference (3) to complete review of the responses. contains the NextEra response to Reference (3).

This letter contains no new regulatory commitments and no revisions to existing commitments.

NextEra Energy Point Beach, LLC, 6610 Nuclear Road, Two Rivers, WI 54241

Document Control Desk Page 2 If there are questions or additional information is required, please contact Mr. James Costedio at 9201755-7427.

A copy of this submittal has been provided to the designated Wisconsin Official.

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

Executed on October 24, 2009.

Very truly yours, NextEra Energy Point Beach, LLC V

For2 Larry Meyer Site Vice President Enclosure cc: Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC PSCW

NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT, UNITS I AND 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION GENERIC LElTER 2008-01, MANAGING GAS ACCUMULATION IN EMERGENCY CORE COOLING, DECAY HEAT REMOVAL, AND CONTAINMENT SPRAY SYSTEMS The following information is provided by NextEra Energy Point Beach, LLC (NextEra) in response to the NRC staff's request for additional information (Reference 3).

Question I Clarify the schedule for submitting a possible license amendment, including the maximum time after NRC acceptance of the TSTF traveler that the possible license amendment will be submitted to the NRC.

NextEra Response NextEra will submit a license amendment within 180 days following NRC approval of the Technical Specification Task Force (TSTF) traveler or consolidated line item improvement process (CLIIP) Notice of Availability of the TSTF traveler in the Federal Register, as appropriate.

Question 2 Describe the evaluation used to produce the plant-specific numbers used in Table 2 of Reference 5, include a discussion of assumptions, and the interim pump gas ingestion limits used to calculate the acceptance criteria in Table 2.

NextEra Response As stated in References ( I ) and (2), the interim pump gas ingestion limits established by the Pressurized Water Reactor Owners Group (PWROG) report, Pump Gas Ingestion Tolerance Criteria: PA-SEE-450 Task 2, Revision 0, dated October 2008, were employed to establish void volume acceptance criteria for containment spray (CS), residual heat removal (RHR) and safety injection (Sl) pump suction piping at Point Beach Nuclear Plant (PBNP).

Table 1 of Reference ( I ) identifies the interim steady-state and transient void fraction criteria for flow velocities ranging from 70% to 120% of the best efficiency point (QBEP) for single-stage and flexible shaft multi-stage pumps. An interim pump gas injection limit of 5% regardless of the pump type was imposed over a period of 0.5 seconds in lieu of the 5 to 20 second range listed in Table 1 of Reference (I). The basis for the approach is described below and from the PWROG report which revealed that a 5% void fraction over a period of 20 seconds or less would not significantly impact pump mechanical integrity or hydraulic performance. The 0.5 second duration was based on the PWROG report and on WCAP-16631, Testing and Evaluation of Gas Transport to the Suction of ECCS Pumps, Revision 0, which determined by testing that peak void fractions last approximately from 0.5 to 2.0 seconds as they are transported through the pump. Further adding to the basis for this approach is that the Froude numbers for the ECCS lines during normal and accident conditions (excluding minimum recirculation lines), were above the Froude number criteria that characterizes void transfer to the pump through the suction piping. By assuming the entire void was transferred to the pump over a shorter duration, a smaller void at each specific piping high point would be specified than if the steady-state criteria were used.

Page 1 of 6

Revision 2 to NRC Staff Criteria for Gas Movement in Suction Lines and Pump Response to Gas, dated March 26, 2009 (ML090900136), provides acceptance criteria to evaluate licensee responses that, if bounded, "may be accepted by NRC staff members without further justification."

In the document, the Staff finds acceptable for transient conditions a 10% void fraction in the range 70% to 120% of the pump best efficiency point (QeEp)and a 5% void fraction outside this QBEprange. In comparison, Table 1 of Reference (1) limits the allowable void volume fraction to 5% for single-stage pumps and to 10% for multi-stage, flexible shaft pumps in the range 70% to 120% of QBEp.NextEra applied a void fraction limit of 5% regardless of the pump type, as discussed above. Therefore, the interim gas injection limits used to establish allowable, initial void volumes in ECCS suction piping were bound by the Staff's criteria.

Table I of Reference (I): Generic Interim Pump Integrity Acceptance Criteria Multi-Stage Multi-Stage Single-Stage Stiff Shaft Flexible Shaft Steady-State 2% 2% 2%

Transient* 5% for 20 sec. 20% .for 20 sec. 10% for 5 sec.

QBEPRange 70%-I 20% 70%-140% 70%-120%

Pump Type WDF CA RLIJ, JHF (transient data)

• ~ransientcriteria are based on pump test data and vendor-supplied information Table 2 of Reference (2) summarizes the allowable, initial void volumes for system piping leading up to the ECCS pump suction. Generic void volume acceptance criteria were developed for each applicable piping system with consideration for operating modes of the system and the location of a potential gas void. NextEra applied the 5% void fraction transient limit and calculated allowable, initial void volumes that could be transported through the pump over 0.5 second with consideration for pump inlet size and flow rate. This established baseline criteria which ensured that the allowable, initial void volumes specified in Table 2 of Reference (2) would not affect pump integrity and hydraulic performance. The values were adjusted for pressure and temperature conditions, using the Ideal Gas Law, to account for RHR hot leg return piping and RHR to SI crossover, or piggyback, piping where gas voids may be compressed as a result of higher pressures and temperatures. For other piping arrangements where the void location is assumed at least 18 feet above the elevation of the pump inlet, the acceptance criteria was based on WCAP-16631 testing that confirmed that peak void fraction at the pump inlet was less than 5%.

The approach also assumed that the entire void moves as a slug to the pump suction and neglected the effect of piping elbows and changes in direction in breaking up the void, and of striping or ribbons where the void moves at a velocity slower than the bulk fluid flow.

Table 2 of Reference (2) values represent threshold criteria for the detection of degraded or nonconforming conditions resulting from gas ingestion in system piping leading up to the ECCS pump suction. If a gas void exceeds Table 2 values, the affected system or train will be declared inoperable. At the discretion of the Shift Manager, a prompt operability determination may be requested using a more detailed gas transport analysis. Factors such as the location of the gas void, the manner in which the void is transported to the pump and the applicable plant mode could result in acceptable void sizes in excess of Table 2 of Reference (2) values. The approach follows the guidance provided in NRC Inspection Manual Part 9900 Technical Guidance, Operability Determinations and Functionality Assessments for Resolution of Degraded or Nonconforming Conditions Adverse to Quality and Safety, dated April 16, 2008 (ML081360529).

Page 2 of 6

Table 2 of Reference (2): Allowable Initial Void Volume Suction Piping Acceptable System Location Void Size -

RH Pump Suction Piping > I 8 ft Above the Pump 0.300 ft3 RH Pump Suction Piping < I 8 ft Above the Pump 0.087 ft3 RH RH Hot Leg Suction Piping at Standby Conditions 1.421 ft3 CSlSl All CSlSl Pump Suction Piping Excluding Piggyback Piping 0.039 ft3 CSISI Piggyback Piping from RHR Discharge 0.103 ft3 The following references were utilized in establishing the methodology for deriving the Table 2 of Reference (2) results.

1 PWROG report Pump Gas Ingestion Tolerance Criteria: PA-SEE-450 Task 2, Revision 0, October 2008.

2. Westinghouse Letter and Attachment, LTR-LIS-08-543, Non-condensable Gas Voids in ECCS Piping; Assessment of Potential Effects on Reactor Coolant System Transients Including Chapter 15 Events, dated August 19, 2008.

3. Fauske & Associates, Inc. Calculation FA1108-70, Gas-Voids Pressure Pulsations Program, Revision 0.

4. WCAP-16631-NP, Testing and Evaluation of Gas Transport to the Suction of ECCS Pumps, Revision 0.

5. EDS Fauske & Associates, Inc. Calculation FA1108-78 Gas Voids Pressure Pulsations Program, Revision 0.

Subsequent to the development of the allowable, initial void volumes listed in Table 2 of Reference (2), a gas transport computer model analysis was performed for selected suction piping locations. The analysis supports the response to GL 2008-01 by evaluating system locations which have the potential for gas accumulation to determine the behavior of these gases during design basis events. The GOTHIC@computer code is used to model the propagation and attenuation of voids in ECCS system suction piping. The GOTHIC@model results allow for the assessment of potential adverse impacts on pump performance from hypothetical void sizes in selected piping locations as well as the evaluation of specific gas volumes in as-found locations.

The GOTHIC@computer code, Version 7.2aWC2, was used for this analysis. This particular release of GOTHIC@allows user control over the maximum diameter for large voids and corrects some deficiencies affecting dynamic pressure losses in the connections between subdivided volumes. The calculation applied acceptance criteria of 2% peak void fraction at the pump suction. This is more conservative than the Staff's acceptance criteria of a 5% void fraction. The results of the GOTHIC@analysis validate the methodology and conservatism used in development of the Table 2 of Reference (2) criteria.

Page 3 of 6

Question 3 Clarify the frequency of periodic venting and inspections.

NextEra Response NextEra ensures that ECCS piping is sufficiently full of water through a combination of periodic venting and ultrasonic examination. NextEra performs monthly venting of both trains of the ECCS and containment spray systems during MODES I, 2, 3, 4, and in MODE 5 prior to entry into MODE 4. Venting of the SI pump casings is also performed, as a good practice, whenever 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> has elapsed since the last venting or operation of the pump. NextEra performs monthly ultrasonic (UT) examinations of potential gas intrusion pathways in ECCS piping. UT examinations are also performed following drainage of in-scope systems for maintenance and during outage recovery.

Question 4 The licensee's "venting procedures require engineering to be informed if detectable gas is found.

The corrective action procedure requires an Action Request (AR) to be written i f a condition adverse to quality is found. " Clarify what criteria will be used to determine if a condition is adverse to quality.

NextEra Response In Reference I, NextEra stated that an Action Request (AR) will be written if a condition adverse to quality is found. A condition adverse to quality, as defined in the NextEra corrective action program, is "... any failure, malfunction, deficiency, deviation, defective item, abnormal occurrence, non-conformance, or out-of control process that has the potential to affect nuclear safety, radiological safety, operability or functionality of safety related structures, systems or components (SSC), or any programmatic or operational aspects associated with nuclear or radiological safety, as well as any reportable industrial safety or environmental safety issues."

Should a gas void be detected in volumes that exceed the allowable initial void volume acceptance criteria, the applicable system or train, as appropriate, is declared inoperable and the condition is entered into the corrective action program. The Shift Manager may, at his discretion, request an prompt operability determination. Prompt operability evaluations are performed by plant engineering on a case-by-case basis using a gas transport analysis. Factors such as the location of the gas void, the manner in which the void is transported to the pump and the applicable plant mode could result in acceptable void sizes in excess of initial void volume acceptance criteria.

To ensure that void volume acceptance criteria are not exceeded, the PBNP Gas Accumulation Management Program (GAMP) establishes assessment action and alert action levels for applicable piping segments, based upon 40% and 70% of the allowable initial void volumes, respectively. Void volumes in excess of these levels, but less than the allowable initial void volume criteria, prompt rigorous corrective measures including increased monitoring frequencies and development of action plans to prevent adverse trends toward inoperability. Incidences of void volumes in excess of alert action or assessment action levels are entered into the corrective action program.

Page 4 of 6

Additionally, the GAMP establishes a void volume trending program that assists in evaluating the effectiveness of venting and flushing activities, and in associating gas accumulation with certain operational activities. If an adverse trend is identified, the condition is entered into the corrective action program and an action plan is developed and implemented to ensure that the adverse trend is resolved. The trending program is applied regardless of whether measured void volumes are less than the alert or assessment threshold action levels described above.

Question 5 Training was not identified in the GL but is considered to be a necessary part of applying procedures and other activities when addressing the issues identified in the GL as the licensee has recognized. Provide a brief description of training.

NextEra Response NextEra adheres to industry accepted initial and continuing training guidance, including classroom instruction on relevant industry and site-specific operating experience (OE) relating to the design, operation and maintenance of systems and components susceptible to, or that may cause, gas intrusion.

Engineering Support Personnel (ESP)

NextEra provides initial training to new engineering support personnel on OE lessons learned from gas intrusion-related industry events.

In response to GL 2008-01, NextEra developed an engineering support continuing training module, Gas Venting. In addition to relevant OE, the lesson plan includes:

a Discussion on actions undertaken by NextEra to minimize andlor prevent gas intrusion.

a Discussion of GL 2008-01, NRC expectations and licensee response.

0 Discussion of the factors that affect solubility of gasses in liquids.

Discussion of gas sources and the consequences of gas intrusion into ECCS systems.

In addition, personnel utilizing UT examinations for the detection of gas voids are trained and certified in UT as NDE Level I I (L) or greater, in accordance with the NextEra nondestructive examination program.

Operations As part of the NextEra Licensed Operator Initial Training program, license candidates receive classroom training, simulator training and perform case studies on OE relating to gas intrusion.

As a part of the NextEra Licensed Operator Continuing Training program, operators receive simulator and classroom training on gas intrusion related OE every two years. In addition, new and revised procedures used by Operations are reviewed to assess training needs relating to gas intrusion. This includes procedures revised as part of the GAMP program.

Page 5 of 6

Maintenance lnstrument and control (I&C), mechanical and electrical maintenance staff receive instruction on relevant OE relating to gas intrusion during initial training entitled, Fittings & lnstrument Lines Installation. I&C staff receive similar instruction in an initial training module entitled, Chemical &

Volume Control System.

The Mechanical and electrical maintenance staffs review industry OE relating to gas intrusion during a continuing training module entitled, Swagelok Biennial Refresher Training. I&C personnel receive similar classroom instruction during pre-outage training.

Page 6 of 6

Text

NEXTera TM POINT BEACH October 24,2009 NRC 2009-0099 10 CFR 50.54(f)

U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Point Beach Nuclear Plant, Units Iand 2 Dockets 50-266 and 50-301 Renewed License Nos. DPR-24 and DPR-27 Response to Reauest for Additional lnformation Regarding Generic Letter 2008-01 Managing Gas Accumulation in Emergencv Core Coolina. Decav Heat Removal and Containment Sprav Svstems

References:

(1) Point Beach, Units 1 and 2, Nine-Month Response to NRC Generic Letter 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems, dated October 14,2008.

(ML082880659)

(2) Point Beach, Unit 1, Nine-Month Supplemental (Post-Outage) Response to NRC Generic Letter 2008-01, dated February 11,2009. (ML090420473)

(3) Point Beach Nuclear Plant, Units 1 and 2 - Request for Additional lnformation Re: Response to Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems" (TAC Nos. MD7864 and MD7865), dated September 25,2009. (ML092650687)

The Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems, on January 1I, 2008. NextEra Energy Point Beach, LLC (NextEra) responded to GL 2008-01 for Point Beach Nuclear Plant (PBNP) Units 1 and 2, via References ( I ) and (2). The NRC requested additional information (RAI) in Reference (3) to complete review of the responses. contains the NextEra response to Reference (3).

This letter contains no new regulatory commitments and no revisions to existing commitments.

NextEra Energy Point Beach, LLC, 6610 Nuclear Road, Two Rivers, WI 54241

Document Control Desk Page 2 If there are questions or additional information is required, please contact Mr. James Costedio at 9201755-7427.

A copy of this submittal has been provided to the designated Wisconsin Official.

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

Executed on October 24, 2009.

Very truly yours, NextEra Energy Point Beach, LLC V

For2 Larry Meyer Site Vice President Enclosure cc: Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC PSCW

NEXTERA ENERGY POINT BEACH, LLC POINT BEACH NUCLEAR PLANT, UNITS I AND 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION GENERIC LElTER 2008-01, MANAGING GAS ACCUMULATION IN EMERGENCY CORE COOLING, DECAY HEAT REMOVAL, AND CONTAINMENT SPRAY SYSTEMS The following information is provided by NextEra Energy Point Beach, LLC (NextEra) in response to the NRC staff's request for additional information (Reference 3).

Question I Clarify the schedule for submitting a possible license amendment, including the maximum time after NRC acceptance of the TSTF traveler that the possible license amendment will be submitted to the NRC.

NextEra Response NextEra will submit a license amendment within 180 days following NRC approval of the Technical Specification Task Force (TSTF) traveler or consolidated line item improvement process (CLIIP) Notice of Availability of the TSTF traveler in the Federal Register, as appropriate.

Question 2 Describe the evaluation used to produce the plant-specific numbers used in Table 2 of Reference 5, include a discussion of assumptions, and the interim pump gas ingestion limits used to calculate the acceptance criteria in Table 2.

NextEra Response As stated in References ( I ) and (2), the interim pump gas ingestion limits established by the Pressurized Water Reactor Owners Group (PWROG) report, Pump Gas Ingestion Tolerance Criteria: PA-SEE-450 Task 2, Revision 0, dated October 2008, were employed to establish void volume acceptance criteria for containment spray (CS), residual heat removal (RHR) and safety injection (Sl) pump suction piping at Point Beach Nuclear Plant (PBNP).

Table 1 of Reference ( I ) identifies the interim steady-state and transient void fraction criteria for flow velocities ranging from 70% to 120% of the best efficiency point (QBEP) for single-stage and flexible shaft multi-stage pumps. An interim pump gas injection limit of 5% regardless of the pump type was imposed over a period of 0.5 seconds in lieu of the 5 to 20 second range listed in Table 1 of Reference (I). The basis for the approach is described below and from the PWROG report which revealed that a 5% void fraction over a period of 20 seconds or less would not significantly impact pump mechanical integrity or hydraulic performance. The 0.5 second duration was based on the PWROG report and on WCAP-16631, Testing and Evaluation of Gas Transport to the Suction of ECCS Pumps, Revision 0, which determined by testing that peak void fractions last approximately from 0.5 to 2.0 seconds as they are transported through the pump. Further adding to the basis for this approach is that the Froude numbers for the ECCS lines during normal and accident conditions (excluding minimum recirculation lines), were above the Froude number criteria that characterizes void transfer to the pump through the suction piping. By assuming the entire void was transferred to the pump over a shorter duration, a smaller void at each specific piping high point would be specified than if the steady-state criteria were used.

Page 1 of 6

Revision 2 to NRC Staff Criteria for Gas Movement in Suction Lines and Pump Response to Gas, dated March 26, 2009 (ML090900136), provides acceptance criteria to evaluate licensee responses that, if bounded, "may be accepted by NRC staff members without further justification."

In the document, the Staff finds acceptable for transient conditions a 10% void fraction in the range 70% to 120% of the pump best efficiency point (QeEp)and a 5% void fraction outside this QBEprange. In comparison, Table 1 of Reference (1) limits the allowable void volume fraction to 5% for single-stage pumps and to 10% for multi-stage, flexible shaft pumps in the range 70% to 120% of QBEp.NextEra applied a void fraction limit of 5% regardless of the pump type, as discussed above. Therefore, the interim gas injection limits used to establish allowable, initial void volumes in ECCS suction piping were bound by the Staff's criteria.

Table I of Reference (I): Generic Interim Pump Integrity Acceptance Criteria Multi-Stage Multi-Stage Single-Stage Stiff Shaft Flexible Shaft Steady-State 2% 2% 2%

Transient* 5% for 20 sec. 20% .for 20 sec. 10% for 5 sec.

QBEPRange 70%-I 20% 70%-140% 70%-120%

Pump Type WDF CA RLIJ, JHF (transient data)

• ~ransientcriteria are based on pump test data and vendor-supplied information Table 2 of Reference (2) summarizes the allowable, initial void volumes for system piping leading up to the ECCS pump suction. Generic void volume acceptance criteria were developed for each applicable piping system with consideration for operating modes of the system and the location of a potential gas void. NextEra applied the 5% void fraction transient limit and calculated allowable, initial void volumes that could be transported through the pump over 0.5 second with consideration for pump inlet size and flow rate. This established baseline criteria which ensured that the allowable, initial void volumes specified in Table 2 of Reference (2) would not affect pump integrity and hydraulic performance. The values were adjusted for pressure and temperature conditions, using the Ideal Gas Law, to account for RHR hot leg return piping and RHR to SI crossover, or piggyback, piping where gas voids may be compressed as a result of higher pressures and temperatures. For other piping arrangements where the void location is assumed at least 18 feet above the elevation of the pump inlet, the acceptance criteria was based on WCAP-16631 testing that confirmed that peak void fraction at the pump inlet was less than 5%.

The approach also assumed that the entire void moves as a slug to the pump suction and neglected the effect of piping elbows and changes in direction in breaking up the void, and of striping or ribbons where the void moves at a velocity slower than the bulk fluid flow.

Table 2 of Reference (2) values represent threshold criteria for the detection of degraded or nonconforming conditions resulting from gas ingestion in system piping leading up to the ECCS pump suction. If a gas void exceeds Table 2 values, the affected system or train will be declared inoperable. At the discretion of the Shift Manager, a prompt operability determination may be requested using a more detailed gas transport analysis. Factors such as the location of the gas void, the manner in which the void is transported to the pump and the applicable plant mode could result in acceptable void sizes in excess of Table 2 of Reference (2) values. The approach follows the guidance provided in NRC Inspection Manual Part 9900 Technical Guidance, Operability Determinations and Functionality Assessments for Resolution of Degraded or Nonconforming Conditions Adverse to Quality and Safety, dated April 16, 2008 (ML081360529).

Page 2 of 6

Table 2 of Reference (2): Allowable Initial Void Volume Suction Piping Acceptable System Location Void Size -

RH Pump Suction Piping > I 8 ft Above the Pump 0.300 ft3 RH Pump Suction Piping < I 8 ft Above the Pump 0.087 ft3 RH RH Hot Leg Suction Piping at Standby Conditions 1.421 ft3 CSlSl All CSlSl Pump Suction Piping Excluding Piggyback Piping 0.039 ft3 CSISI Piggyback Piping from RHR Discharge 0.103 ft3 The following references were utilized in establishing the methodology for deriving the Table 2 of Reference (2) results.

1 PWROG report Pump Gas Ingestion Tolerance Criteria: PA-SEE-450 Task 2, Revision 0, October 2008.

2. Westinghouse Letter and Attachment, LTR-LIS-08-543, Non-condensable Gas Voids in ECCS Piping; Assessment of Potential Effects on Reactor Coolant System Transients Including Chapter 15 Events, dated August 19, 2008.

3. Fauske & Associates, Inc. Calculation FA1108-70, Gas-Voids Pressure Pulsations Program, Revision 0.

4. WCAP-16631-NP, Testing and Evaluation of Gas Transport to the Suction of ECCS Pumps, Revision 0.

5. EDS Fauske & Associates, Inc. Calculation FA1108-78 Gas Voids Pressure Pulsations Program, Revision 0.

Subsequent to the development of the allowable, initial void volumes listed in Table 2 of Reference (2), a gas transport computer model analysis was performed for selected suction piping locations. The analysis supports the response to GL 2008-01 by evaluating system locations which have the potential for gas accumulation to determine the behavior of these gases during design basis events. The GOTHIC@computer code is used to model the propagation and attenuation of voids in ECCS system suction piping. The GOTHIC@model results allow for the assessment of potential adverse impacts on pump performance from hypothetical void sizes in selected piping locations as well as the evaluation of specific gas volumes in as-found locations.

The GOTHIC@computer code, Version 7.2aWC2, was used for this analysis. This particular release of GOTHIC@allows user control over the maximum diameter for large voids and corrects some deficiencies affecting dynamic pressure losses in the connections between subdivided volumes. The calculation applied acceptance criteria of 2% peak void fraction at the pump suction. This is more conservative than the Staff's acceptance criteria of a 5% void fraction. The results of the GOTHIC@analysis validate the methodology and conservatism used in development of the Table 2 of Reference (2) criteria.

Page 3 of 6

Question 3 Clarify the frequency of periodic venting and inspections.

NextEra Response NextEra ensures that ECCS piping is sufficiently full of water through a combination of periodic venting and ultrasonic examination. NextEra performs monthly venting of both trains of the ECCS and containment spray systems during MODES I, 2, 3, 4, and in MODE 5 prior to entry into MODE 4. Venting of the SI pump casings is also performed, as a good practice, whenever 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> has elapsed since the last venting or operation of the pump. NextEra performs monthly ultrasonic (UT) examinations of potential gas intrusion pathways in ECCS piping. UT examinations are also performed following drainage of in-scope systems for maintenance and during outage recovery.

Question 4 The licensee's "venting procedures require engineering to be informed if detectable gas is found.

The corrective action procedure requires an Action Request (AR) to be written i f a condition adverse to quality is found. " Clarify what criteria will be used to determine if a condition is adverse to quality.

NextEra Response In Reference I, NextEra stated that an Action Request (AR) will be written if a condition adverse to quality is found. A condition adverse to quality, as defined in the NextEra corrective action program, is "... any failure, malfunction, deficiency, deviation, defective item, abnormal occurrence, non-conformance, or out-of control process that has the potential to affect nuclear safety, radiological safety, operability or functionality of safety related structures, systems or components (SSC), or any programmatic or operational aspects associated with nuclear or radiological safety, as well as any reportable industrial safety or environmental safety issues."

Should a gas void be detected in volumes that exceed the allowable initial void volume acceptance criteria, the applicable system or train, as appropriate, is declared inoperable and the condition is entered into the corrective action program. The Shift Manager may, at his discretion, request an prompt operability determination. Prompt operability evaluations are performed by plant engineering on a case-by-case basis using a gas transport analysis. Factors such as the location of the gas void, the manner in which the void is transported to the pump and the applicable plant mode could result in acceptable void sizes in excess of initial void volume acceptance criteria.

To ensure that void volume acceptance criteria are not exceeded, the PBNP Gas Accumulation Management Program (GAMP) establishes assessment action and alert action levels for applicable piping segments, based upon 40% and 70% of the allowable initial void volumes, respectively. Void volumes in excess of these levels, but less than the allowable initial void volume criteria, prompt rigorous corrective measures including increased monitoring frequencies and development of action plans to prevent adverse trends toward inoperability. Incidences of void volumes in excess of alert action or assessment action levels are entered into the corrective action program.

Page 4 of 6

Additionally, the GAMP establishes a void volume trending program that assists in evaluating the effectiveness of venting and flushing activities, and in associating gas accumulation with certain operational activities. If an adverse trend is identified, the condition is entered into the corrective action program and an action plan is developed and implemented to ensure that the adverse trend is resolved. The trending program is applied regardless of whether measured void volumes are less than the alert or assessment threshold action levels described above.

Question 5 Training was not identified in the GL but is considered to be a necessary part of applying procedures and other activities when addressing the issues identified in the GL as the licensee has recognized. Provide a brief description of training.

NextEra Response NextEra adheres to industry accepted initial and continuing training guidance, including classroom instruction on relevant industry and site-specific operating experience (OE) relating to the design, operation and maintenance of systems and components susceptible to, or that may cause, gas intrusion.

Engineering Support Personnel (ESP)

NextEra provides initial training to new engineering support personnel on OE lessons learned from gas intrusion-related industry events.

In response to GL 2008-01, NextEra developed an engineering support continuing training module, Gas Venting. In addition to relevant OE, the lesson plan includes:

a Discussion on actions undertaken by NextEra to minimize andlor prevent gas intrusion.

a Discussion of GL 2008-01, NRC expectations and licensee response.

0 Discussion of the factors that affect solubility of gasses in liquids.

Discussion of gas sources and the consequences of gas intrusion into ECCS systems.

In addition, personnel utilizing UT examinations for the detection of gas voids are trained and certified in UT as NDE Level I I (L) or greater, in accordance with the NextEra nondestructive examination program.

Operations As part of the NextEra Licensed Operator Initial Training program, license candidates receive classroom training, simulator training and perform case studies on OE relating to gas intrusion.

As a part of the NextEra Licensed Operator Continuing Training program, operators receive simulator and classroom training on gas intrusion related OE every two years. In addition, new and revised procedures used by Operations are reviewed to assess training needs relating to gas intrusion. This includes procedures revised as part of the GAMP program.

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Maintenance lnstrument and control (I&C), mechanical and electrical maintenance staff receive instruction on relevant OE relating to gas intrusion during initial training entitled, Fittings & lnstrument Lines Installation. I&C staff receive similar instruction in an initial training module entitled, Chemical &

Volume Control System.

The Mechanical and electrical maintenance staffs review industry OE relating to gas intrusion during a continuing training module entitled, Swagelok Biennial Refresher Training. I&C personnel receive similar classroom instruction during pre-outage training.

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