ML15222B116

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Korea Electric Power Corporation / Korea Hydro & Nuclear Power Co., Ltd - Response to Request for Additional Information 63-7983 for Questions on a 30-Day Response Cycle
ML15222B116
Person / Time
Site: 05200046
Issue date: 08/10/2015
From:
Korea Electric Power Corp, Korea Hydro & Nuclear Power Co, Ltd
To:
Document Control Desk, NRC/NRO/DNRL
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ML15222B114 List:
References
MKD/NW-15-0077L
Download: ML15222B116 (35)
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06.02.02 1 / 2 KEPCO/KHNP RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION APR1400 Design Certification Korea Electric Power Corporation / Korea Hydro & Nuclear Power Co., LTD Docket No.52-046 RAI No.: 63-7983 SRP Section: 06.02.02 - Containment Heat Removal Systems Application Section: 6.2.2 Date of RAI Issue: 07/07/2015 Question No. 06.02.02-12 Technical Report APR1400-E-N-NR-14001-P, Section 4.2, Introduction, states the objective of ex-vessel downstream effects evaluation is to assess the systems and components of the APR1400 emergency core cooling system (ECCS) and the containment spray system (CSS) to guarantee that these systems are designed to be operable under post loss-of-coolant accident (LOCA) conditions. Guarantee is not a defined term with respect to assessment of the operability of systems and components. The applicant is requested to define or revise the use of the term guarantee in Section 4.2 of the technical report.

Response

The term of guarantee will be changed to ensure to clarify the statement.

Impact on DCD There is no impact on the DCD.

Impact on PRA There is no impact on the PRA.

Impact on Technical Specifications There is no impact on the Technical Specifications.

06.02.02 2 / 2 KEPCO/KHNP Impact on Technical/Topical/Environmental Reports Technical Report APR1400-E-N-NR-14001-P/NP, Section 4.2 will be revised as indicated in the attached markup.

RAI 63-7983_Question 06.02.02-12 Non-Proprietary Attachment (1/1)

Design Features to Address GSI-191 APR1400-E-N-NR-14001-NP, Rev.0



between each fiber addition is approximately seven pool turnovers. The resulting bypass fiber weights are presented in Table 4.1-2.

To determine the plant strainer bypass debris, the cumulative quantity of bypass debris from the prototype test is scaled by a ratio of the plant strainer to the prototype strainer (600/75.1 = 8.0). The cumulative bypass quantities for debris loads are presented in Table 4.1-2. The total bypass debris is the sum of the bypass debris for all active strainers and presented in Table 4.1-3.

Total bypass debris for the APR1400 with 6.80 kg (15 lbm) of latent fiber is 1.67 kg (3.68 lbm).

4.2 Ex-Vessel Downstream Effects ensure The objective of ex-vessel downstream effects evaluation is to assess the systems and components of the APR 1400 emergency core cooling system (ECCS) and the containment spray system (CSS) to guarantee that these systems are designed to be operable under post loss-of-coolant accident conditions (LOCA).

4.2.1 System Descriptions 4.2.1.1 Emergency Core Cooling System The ECCS is designed to perform the following major functions:

1) Inject borated water into the reactor coolant system (RCS) through direct vessel injection (DVI) nozzles to flood and cool the core following a LOCA, thus preventing a significant amount of cladding failure along with subsequent release of fission products into the containment and maintaining the core subcritical
2) Provide removal of heat form the core for extended periods of time following a LOCA
3) Inject borated water into the RCS to increase shutdown margin following a rapid cooldown of the system due to a steam line break
4) Prevent boron precipitation in the RCS during long-term mode of operation
5) Provide inventory makeup and boration for reactivity control during a safe shutdown if necessary
6) Provide feed flow for feed-and-bleed operation in conjunction with pressurizer (PZR) pilot operated safety relief valves (POSRVs) to remove core decay heat during beyond design basis event of a total loss of feed water to steam generators



The ECCS consists of four mechanically separate trains, four safety injection tanks (SITs), and associated valves, piping, instrumentation. Each train contains one SI pump, one SIT, and associated suction and discharge paths. The pumps take suction from the in-containment refueling water storage tank (IRWST).

Motor-operated valves and pump in each train receive power from either the normal power source or the emergency diesel generators. Power connections are through four independent electrical trains with each train providing power to one bus. In the event of a LOCA, in conjunction with a single failure in the electrical supply, the flow from at least two safety injection pumps (SIPs) is available for core protection.

One independent electrical train, as described above, supplies power to three SIPs and associated valves.

Other independent electrical trains supply power to the remaining three SIPs and associated valves.





KEPCO & KHNP 58

06.02.02 1 / 2 KEPCO/KHNP RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION APR1400 Design Certification Korea Electric Power Corporation / Korea Hydro & Nuclear Power Co., LTD Docket No.52-046 RAI No.: 63-7983 SRP Section: 06.02.02 - Containment Heat Removal Systems Application Section: 6.2.2 Date of RAI Issue: 07/07/2015 Question No. 06.02.02-13 Technical Report APR1400-E-N-NR-14001-P, Section 4.2.2.3, Components of Interest, states that Table 4.2-1, Components in the Flow Path during an LBLOCA, of Technical Report APR1400-E-N-NR-14001-P lists the ECCS/shutdown cooling system (SCS)/in-containment refueling water storage tank (IRWST) components in the downstream effects evaluation. The components in the ECCS flow path during small break LOCA (SBLOCA) and large break LOCA (LBLOCA) operations include pumps, heat exchangers, valves, orifices, containment spray nozzles, and piping. The NRC staff reviewed the components of interest and identified the following inconsistencies:

The applicant states that Table 4.2-1 lists ECCS/SCS/IRWST components in the downstream effects evaluation. However, Table 4.2-1 lists only components in the safety injection system (SIS) and CSS. The applicant is requested to clarify ECCS/SCS/IRWST components in the downstream effects evaluation in the technical report.

Table 4.2-1 lists valves in the CSS miniflow line but does not include the CSS miniflow heat exchangers or the 4-inch miniflow recirculation piping. The applicant is requested to clarify in the technical report whether these components are required to be included in the downstream effects evaluation. Also, the applicant is requested to review and confirm that all applicable SI and CS components required to be included in the downstream effects evaluation are included in Table 4.2-1 with any changes to the table as appropriate.

Response

Components in the flow path during an LBLOCA include the ECCS and CSS components.

Section 4.2.2.3 of the Technical Report will be revised to be consistent with Table 4.2-1.

06.02.02 2 / 2 KEPCO/KHNP The CS pump miniflow heat exchangers and the 4-inch miniflow recirculation piping are included in the downstream effects evaluation. KHNP has reviewed the SI and CS components required to be included in the downstream effects evaluation and has either added, changed, or deleted them to Table 4.2-1.

Impact on DCD There is no impact on the DCD.

Impact on PRA There is no impact on the PRA.

Impact on Technical Specifications There is no impact on the Technical Specifications.

Impact on Technical/Topical/Environmental Reports Technical Report APR1400-E-N-NR-14001-P/NP, Section 4.2.2.3 and Table 4.2-1 will be revised as indicated in the attached markup.

RAI 63-7983_Question 06.02.02-13 Non-Proprietary Attachment (1/3)

Design Features to Address GSI-191 APR1400-E-N-NR-14001-NP, Rev.0





2) SBLOCA scenario The most limiting SBLOCA is assumed to occur in a DVI line break LOCA.



The worst case SBLOCA assumes some time delay before pumped flow reaches the core. For the larger range of small breaks, the rate of blowdown is such that the increase in fuel clad temperature is terminated mainly by the SITs, with pumped flow then providing continued cooling.

As break size continues to decrease, the SITs and an SIP both play a part in terminating the rise in clad temperature.



Above process (blowdown, passive injection, and recovery) takes longer time period compared with LBLOCA and the duration depends on the break size and the performance of the ECCS.



For this evaluation, the SBLOCA is bounded by the LBLOCA and post-LOCA long-term cooling.

The debris quantity and the ECCS flows during the SBLOCA are considered much smaller than during the LBLOCA.



Therefore, the SBLOCA scenario in the evaluation of the downstream effect is bounded by the conditions of the LBLOCA scenario.



4.2.2.2 Mission Time Mission time represents the maximum period of time for which a System, Structure or Component remains to perform their safety function. It is the accident analysis credit time.



For this evaluation, the mission time of the downstream effect evaluation is defined as 30 days following the Chapter 15 of the DCD (Reference [3-1]).

4.2.2.3 Components of Interest ECCS and CSS Table 4.2-1 lists the ECCS/SCS/IRWST components in the downstream effects evaluation. These components are in the ECCS flow path during SBLOCA and LBLOCA operations.



and CSS 4.2.2.4 Post-LOCA Fluid Constituents Debris in the post-LOCA fluid consists of latent debris (particulate and fiber), coating particles (i.e., epoxy),

insulation materials, and miscellaneous debris. Miscellaneous debris includes materials placed inside containment for an operational, maintenance, or engineering purpose. Materials include tape, tags, stickers, adhesive labels used for component identification, fire barrier materials, and other materials (e.g.,

rope, fire hoses, ventilation filters, plastic sheeting).



Debris sizes are classified as particulates, fines, and large pieces. The sizes in Table 4.2-2 are based on the following:



KEPCO & KHNP 61

RAI 63-7983_Question 06.02.02-13 Non-Proprietary Attachment (2/3)

Design Features to Address GSI-191 APR1400-E-N-NR-14001-NP, Rev.0



Table 4.2-1 Components in the Flow Path during an LBLOCA (1 of 2)

Component Description Pumps Type: multi-stage centrifugal pump SI pump Arrangement: horizontal (SI-PP02A/02B/02C/02D) (1)

Flow rate: ~4,675 L/min (1,235 gpm) (maximum)

Type: centrifugal CS Pump Arrangement: vertical (CS-PP01A/01B) (1)

Flow rate: ~24,605 L/min (6,500 gpm) (maximum)

Heat Exchangers Type: shell and tube, U-tube, horizontally mounted Number of shell in series:1 CS Heat Exchanger Number of tube passes: 2 (CS-PP01A/01B) Tube material; austenitic steel Flow rate: ~18,927 L/min (5,000 gpm) (during LBLOCA HE Containment Spray)

Valves 14 CS-V1001/1002 Swing check, 18 inch 14 CS-V1003/1004 Gate (manual), 18 inch CS-V1007/1008 Swing check, 14 inch CS-V1015/1016/1017/1018 Globe (manual), 4 inch CS-V001/002/003/004 Gate (MOV), 14 inch SI-V304/305 Gate (MOV), 20 inch SI-V470/402/130/131 Gate (manual), 10 inch SI-V404/405/434/446 Swing check, 4 inch SI-V435/447/476/478 Gate (manual), 4 inch SI-V308/309 Gate (MOV), 20 inch SI-V347/348 Gate (MOV), 18 inch SI-V157/158 Swing check, 18 inch SI-V340/342 Gate (MOV), 18 inch SI-V424/426/448/451 Swing check, 4 inch SI-V410/411/412/413 Globe (manual), 4 inch SI-V302/303 Globe (MOV), 4 inch SI-V100/101 Swing check, 10 inch SI-V395 Gate (MOV), 10 inch SI-V959 Gate (manual), 10 inch SI-V106/107 Gate (manual), 18 inch SI-V568/569 Swing check, 14 inch SI-V578/579 Gate (manual), 14 inch SI-V341/343 Gate (MOV), 14 inch SI-V265/269 Globe (Manual), 4 inch SI-V604/609 Gate (MOV), 4 inch SI-V344/346 Gate (MOV), 18 inch Note :

(1) Including minimum bypass flow CS Pump Miniflow Heat Type: shell and tube, U-tube, horizontally mounted



Exchanger (CS-HE02A/02B) Number of shell in series:1 KEPCO & KHNP Number of tube passes: 2 90

Tube material; austenitic steel Flow rate: ~ 1,817 L/min (480 gpm)

RAI 63-7983_Question 06.02.02-13 Non-Proprietary Attachment (3/3)

Design Features to Address GSI-191 APR1400-E-N-NR-14001-NP, Rev.0



Table 4.2-1 Components in the Flow Path during an LBLOCA (2 of 2)

Component Description Valves (Cont.)

SI-V159/160 Swing check, 18 inch SI-V616/626/636/646 Globe (MOV), 4 inch SI-V113/123/133/143 Swing check, 4 inch SI-V540/541/542/543 Swing check, 4 inch SI-V614/624/634/644 Gate (MOV), 12 inch SI-V217/227/237/247 Swing check, 12 inch SI-V217/227/237/247 Swing check, 12 inch SI-V321/331 Globe (MOV, throttling), 4 inch SI-V523/533 Swing check, 4 inch SI-V957/V958 Gate (manual), 4 inch SI-V522/532 Swing check, 4 inch Orifice CS-OR01A/B CS pump miniflow orifice, 4 inch CS-FE338/348 CS pump outlet flow instrument orifice, 14 inch CS-02A/B, 03A/B CS main spring ring header orifice, 8 inch CS-OR04A/B CS main spring ring header orifice, 4 inch CS-OR05A/B, 06A/B CS auxiliary spring ring header orifice, 4 inch SI-OR01A/B/C/D, 08A/B/C/D, 20A/B/C/D SI pump miniflow orifice, 4 inch SI-OR02A/B SC pump miniflow orifice, 4 inch SI-OR06A/B/C/D SI pump outlet flow orifice, 12 inch SI-OR07A/B Hotleg injection flow orifice, 4 inch SI-FE311D/321B/331C/341A SI pump outlet flow instrument orifice, 4 inch SI-FE390C/390D Hotleg injection flow instrument orifice, 4 inch Containment Spray Nozzle Main spray nozzle Orifice size 13.1 mm (0.516 inch)

Auxiliary spray nozzle Orifice size 5.6 mm (0.22 inch)

Piping 16 inch CS pump suction line (SS Sch. 80) 14 inch CS pump discharge line (SS Sch. 80) 12 inch CS pump discharge line (SS Sch. 80S) 14 inch CS spray header line (SS Sch. STD) 12 inch CS spray header line (SS Sch. 40S) 8 inch CS spray header line (SS Sch 40S) 6 inch CS spray ring line (SS Sch 40S) 4 inch CS spray ring line (SS Sch 40S) 24 inch SI pump suction line (SS Sch. 80) 20 inch SI pump suction line (SS Sch. 80) 10 inch SI pump suction line (SS Sch. 80S) 4 inch SI pump discharge line (SS Sch. 120) 4 inch SI pump miniflow line (SS Sch. 120) 4 inch SI pump hot leg Injection line (SS Sch. 120) 4 inch SI pump discharge line (SS Sch. 160) 12 inch SI pump discharge line (SS Sch. 160) 4 inch CS pump miniflow line(SS Sch. 40)

 10 inch SI IRWST return line (SS Sch. 120)

KEPCO & KHNP 91

06.02.02 1 / 2 KEPCO/KHNP RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION APR1400 Design Certification Korea Electric Power Corporation / Korea Hydro & Nuclear Power Co., LTD Docket No.52-046 RAI No.: 63-7983 SRP Section: 06.02.02 - Containment Heat Removal Systems Application Section: 6.2.2 Date of RAI Issue: 07/07/2015 Question No. 06.02.02-15 Technical Report APR1400-E-N-NR-14001-P, Section 4.2.2.5, ECCS Flow Rate and Flow Velocity, lists the flow rates used for the evaluation of debris settlement and component wear during an LBLOCA and states that the minimum flow rate of the SIS and CSS pumps at shutoff head conditions will be verified during component procurement. However, items 8 and 9 in Section 4.2.3.1 states that both shutoff head and run-out conditions for SIS and CSS pumps will be verified by the vendor. For consistency, the NRC staff requests that the applicant revise Section 4.2.2.5 in the technical report to specify that flow rates at run-out conditions will be verified during procurement.

Response

Both shutoff head and run-out conditions for the SIS and CSS pumps will be verified by the vendor. Therefore, Section 4.2.2.5 of the Technical Report will be revised to be consistent with Section 4.2.3.1.

Impact on DCD There is no impact on the DCD.

Impact on PRA There is no impact on the PRA.

Impact on Technical Specifications There is no impact on the Technical Specifications.

06.02.02 2 / 2 KEPCO/KHNP Impact on Technical/Topical/Environmental Reports Technical Report APR1400-E-N-NR-14001-P/NP, Section 4.2.2.5 will be revised as indicated in the attached markup.

RAI 63-7983_Question 06.02.02-15 Non-Proprietary Attachment (1/1)

Design Features to Address GSI-191 APR1400-E-N-NR-14001-NP, Rev.0



Safety Injection Pump flow is assumed to be 303 L/min (80 gpm) for evaluating debris settlement in the SIS. Flow is assumed to be 6,057 L/min (1,600 gpm) for component wear rate evaluations.

Engineering design range of flow is 397 L/min (105 gpm) at shutoff and 4,675 L/min (1,235 gpm) at runout.



CS pump flow is assumed to be 1,552 L/min (410 gpm) for evaluating debris settlement in the CSS. Flow is assumed to be 26,963 L/min (7,123 gpm) for component wear rate evaluations. Engineering design range of flow is 1,817 L/min (480 gpm) at shutoff and 24,605 L/min (6,500 gpm) at runout. The component wear rate evaluation is detailed in Subsection 4.2.3.1.



The terminal settling velocities of the debris source materials are listed in Table 4.2-4. The velocity of the debris in the post-LOCA fluid is equal to the velocity of the fluid. If the ECCS fluid velocity is greater than the terminal settling velocity of the debris, the debris will not settle.

and run-out



The minimum flow rate of the SI and CS pumps at shutoff head conditions will be verified during component procurement.



4.2.2.6 Summary of Assumptions and Conservatisms Assumptions and conservatisms used in this evaluation are summarized as follows:



1) Only 100% of all particulates (i.e., coating debris, latent particulates) and 100% of latent fiber are assumed to pass through the strainers and enter into the ECCS and CSS. RMI doesnt bypass through the sump strainer because the size of the RMI debris is greater than the perforated plate hole size sump strainer.



2) SIP flow is assumed to be 303 L/min (80 gpm) for the purpose of calculating settling velocities.

Flow is assumed to be 6,057 L/min (1,600 gpm) for the purpose of component wear rate evaluations. Engineering design range of flow is 397 L/min (105 gpm) at shutoff and 4,675 L/min (1,235 gpm) at runout.



3) CSP flow is assumed to be 1,552 L/min (410 gpm) for the purposes of calculating settling velocities. Flow is assumed to be 26,963 L/min (7,123 gpm) for the purpose of component wear rate evaluations. Engineering design range of flow is 1,817 L/min (480 gpm) at shutoff and 24,605 L/min (6,500 gpm) at runout.



4) Wear is calculated from time zero, i.e. start of the event. Worst case fluid properties are assumed to be present. This assumption is conservative since it does not credit debris transport or the slow increase of fluid properties due to long term mixing.



5) Fluid velocity through a single CS heat exchanger tube is assumed to be 4.57 m/s (15 ft/s). A nominal design and operating heat exchanger velocity range is 0.91 to 3.05 m/s (3 to 10 ft/s).

Therefore, the use of 4.57 m/s (15 ft/s) is conservative from a heat exchanger design perspective and bounds the heat exchanger design and procurement specifications.



Table 4.2-5 lists the amount of debris in the post-LOCA fluid (downstream of the IRWST sump strainer) that will be used for confirmatory tests. The amount of debris in the ECCS during post-LOCA operation is based on above assumption 1). The amount of latent debris in Table 4.2-5 is conservatively based on the maximum amount of latent particulates and 100% of the maximum amount of fiber listed in Table 4.2-3.



KEPCO & KHNP 63

06.02.02 1 / 2 KEPCO/KHNP RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION APR1400 Design Certification Korea Electric Power Corporation / Korea Hydro & Nuclear Power Co., LTD Docket No.52-046 RAI No.: 63-7983 SRP Section: 06.02.02 - Containment Heat Removal Systems Application Section: 6.2.2 Date of RAI Issue: 07/07/2015 Question No. 06.02.02-17 Technical Report APR1400-E-N-NR-14001-P, Section 4.2.3.1, SI and CS Pump Evaluation, states that the SIS and CSS pumps and associated mechanical seals will be qualified to operate with the post-LOCA fluids for at least 30 days, using the qualification guidance of ASME Standard QME-1-2007 as endorsed by RG 1.100, Seismic Qualification of Electrical and Active Mechanical Equipment and Functional Qualification of Active Mechanical Equipment for Nuclear Power Plants, Revision 3. RG 1.100, Revision 3, states that ASME QME-1-2007 is an NRC staff approved methodology for the qualification of pumps and valves, and when a licensee commits to the use of QME-1-2007 for qualification of pumps and valves, the criteria and procedures become part of the basis for the qualification program. Therefore, the staff does not consider referencing QME-1-2007 alone as a guide to be sufficient in specifying the qualification methodology. Therefore, the NRC staff requests that the applicant revise the technical report to specify that the pump and valve qualification will be in accordance with ASME QME-1-2007 as accepted in RG 1.100, Revision 3. The same revision should be made wherever QME-1-2007 is referenced in the report, including the wear rate evaluation description in Section 4.2.3.3.2.

Response

The words using the qualification guidance of ASME QME-1-2007 will be changed to in accordance with ASME QME-1-2007 throughout the report.

Impact on DCD There is no impact on the DCD.

06.02.02 2 / 2 KEPCO/KHNP Impact on PRA There is no impact on the PRA.

Impact on Technical Specifications There is no impact on the Technical Specifications.

Impact on Technical/Topical/Environmental Reports Technical Report APR1400-E-N-NR-14001-P/NP, Section 4.2.3.1 and 4.2.3.3.2 will be revised as indicated in the attached markup.

RAI 63-7983_Question 06.02.02-17 Non-Proprietary Attachment (1/2)

Design Features to Address GSI-191 APR1400-E-N-NR-14001-NP, Rev.0





The size range of the debris materials is based on (i) the assumption that 100% of particulates will bypass the ECCS strainers, and (ii) guidance from NEI 04-07 Volume 2 Appendix V. The concentration of the post-LOCA fluid constituents is conservatively estimated based on the assumption that the IRWST 3

contains 946.4 m (250,000 gallons) of water during post-LOCA operation, which is less than the minimum 3

IRWST water volume of 993.2 m (262,388 gallons). Estimating the debris concentration at less than the expected IRWST volume yields a more concentrated debris-laden fluid for confirmatory tests, and produces conservative test results.

4.2.3 ECCS Component Evaluations This section evaluates the ECCS pumps, heat exchangers, valves, instrument tubes, and piping regarding wear, blockage, and fouling (heat exchanger).



4.2.3.1 SI and CS Pump Evaluation The SI pumps are motor-driven horizontal, multistage, centrifugal pumps with mechanical seals. The pumps are sized to deliver 3,085 L/min (815 gpm) at a discharge head of 869 m (2,850 ft). The CS pumps are motor-driven centrifugal pumps with mechanical seals. The pumps are sized to deliver 20,536 L/min (5,425 gpm) (including bypass flow 1,609 L/min (425 gpm)) at a discharge head of 125 m (410 ft). The 100% capacity design flow rate is based upon a 57.5 L/min (15.2 gpm) flow per nozzle.



The SI and CS pumps and associated mechanical seals will be qualified to operate with the post-LOCA fluids for at least 30 days, using the qualification guidance of ASME QME-1-2007 endorsed by RG1.100 Revision 3. As part of the qualification process, the pump vendor, at a minimum, will fulfill the following pump criteria:

 in accordance with

1) Provide tests and/or analyses to confirm that the opening sizes and internal running clearances of the SI and CS pumps yield acceptable operation in post-LOCA fluids for at least 30 days. Also, provide a list of the opening sizes and internal running clearances in the qualification documentation.



2) Provide hydraulic performance test results and/or analyses to confirm that the SI and CS pumps can provide the required safety injection flow for at least 30 days of ECCS post-LOCA operation.



3) Provide tests and/or analyses to confirm that the wear rates of the SI and CS pump wetted surface materials (e.g., wear rings, pump internals, bearing, and casing) provide acceptable operation in the post-LOCA fluids for at least 30 days. Also, provide a list of the wetted pump surfaces materials, hardness of each material, and verification of acceptable wear rates in the qualification documentation.



4) Provide mechanical performance (i.e., pump vibration, rotor dynamics, and bearing load) test results and/or analyses to confirm that there will be no adverse changes in system vibration response or rotor dynamics performance during ECCS operation for at least 30 days. Also, provide relevant test results and/or analyses to confirm that any increases in internal bypass flow caused by impeller or casing wear will not decrease the performance of the pumps or cause accelerated internal wear for at least 30 days of post-LOCA operation.



5) Provide mechanical seal assembly performance test results and/or analyses to confirm that ECCS



KEPCO & KHNP 64

RAI 63-7983_Question 06.02.02-17 Non-Proprietary Attachment (2/2)

Design Features to Address GSI-191 APR1400-E-N-NR-14001-NP, Rev.0



through the sump strainer. Therefore the valves do not clog due to post-LOCA insulation debris.

4) Orifice



ECCS and CSS flow is controlled though a combination of orifices and throttled valves. Orifices are used for throttling system flow. ECCS and CSS pressure and flow are monitored in the MCR.

The orifice sizes are above 20.3 mm (0.8 inch). Flow velocities in all cases are above the settling velocities of the post-LOCA fluid (Table 4.2-6). Therefore, the potential of orifice plugging is very low.

5) Spray Nozzles



The containment main spray nozzles and auxiliary spray nozzles has an orifice of 13.1 mm (0.516 inch) and 5.6 mm (0.22 inch) diameter, respectively. This orifice is the smallest portion of spray nozzle. The strainer hole size is 2.38 mm (0.094 inch). Containment spray nozzles are significantly larger than the strainer hole size. Their one-piece design provides a large, unobstructed flow passage that resists clogging by particles. Therefore, the potential of spray nozzle plugging is very low.

4.2.3.3.2 Wear Rate Evaluation for Valves, Orifices and Pipes Erosive wear is caused by particles that impinge on a component surface and remove material from the surface because of momentum effects. The wear rate of a material depends on the debris type, debris concentration, material hardness, flow velocity, and valve position.



Flow rates of 6,057 L/min (1,600 gpm) and 26,963 L/min (7,123 gpm)) for SIS and CSS, respectively, are conservatively assumed for the wear rate evaluation of the components listed in Table 4.2-1. The ECCS design flow rates listed in Table 4.2-1 include the maximum flow rate of the SI pump, CS pump, and the sum of the SIS and CSS flows based on system configuration.



Table 4.2-7 contains a summary of the piping and orifice wear calculation. Based upon the results of wear evaluation for piping and orifice, it is concluded that the system piping and component flow resistances will change minimally during the course of the LOCA. Therefore, flow balances and system performance are not affected in an appreciable manner. The resulting flows and pressures are consistent or conservative with respect to the accident analysis. The minor resistance changes do not affect the system flow calculations and design basis analysis.

 in accordance with The wear rate of ECCS valves will be provided by the vendor. The vendor will qualify the ECCS valves to operate with the post-LOCA fluids for at least 30 days, using the qualification guidance of ASME QME-1-2007 endorsed by RG1.100 Revision 3. As part of the qualification process, the vendor will provide data and/or analyses to support acceptable wear rates during operation in post-LOCA fluids (Table 4.2-5) at the associated flow velocities listed in Table 4.2-6.



Vendor(s) will also provide tests and/or analyses to support acceptable wear rates of pipes and orifices.

In addition, an analysis will be provided to confirm that the overall system resistance/pressure drop across the ECCS is consistent with the safety analysis results for the 30 day mission time.



For conservatism, vendors will perform component wear evaluations at the assumed flow rates/velocities.



KEPCO & KHNP 68

06.02.02 1 / 2 KEPCO/KHNP RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION APR1400 Design Certification Korea Electric Power Corporation / Korea Hydro & Nuclear Power Co., LTD Docket No.52-046 RAI No.: 63-7983 SRP Section: 06.02.02 - Containment Heat Removal Systems Application Section: 6.2.2 Date of RAI Issue: 07/07/2015 Question No. 06.02.02-18 Technical Report APR1400-E-N-NR-14001-P, Section 4.2.3.1, states that as part of the qualification process, the pump vendor, at a minimum, will fulfill specific pump qualification criteria. The pump criteria specify that qualification will be performed using tests and/or analyses. However, to be consistent with ASME QME-1-2007 as accepted by RG 1.100, Revision 3, the criteria should specify qualification of pumps by test or a combination of test and analysis. Therefore, the NRC staff requests that the applicant revise the technical report to specify that the qualification of pumps will be accomplished by test or a combination of test and analysis. The same revision should be made wherever qualification using this standard is referenced in the report, including the wear rate evaluation description in Section 4.2.3.3.2.

Response

In accordance with ASME QME-1-2007, the words tests and/or analyses will be changed to tests or a combination of tests and analyses throughout the report.

Impact on DCD There is no impact on the DCD.

Impact on PRA There is no impact on the PRA.

Impact on Technical Specifications There is no impact on the Technical Specifications.

06.02.02 2 / 2 KEPCO/KHNP Impact on Technical/Topical/Environmental Reports Technical Report APR1400-E-N-NR-14001-P/NP, Sections 4.2.3.1, 4.2.3.2.2, and 4.2.3.3.2 will be revised as indicated in the attached markup.

RAI 63-7983_Question 06.02.02-18 Non-Proprietary Attachment (1/4)

Design Features to Address GSI-191 APR1400-E-N-NR-14001-NP, Rev.0





The size range of the debris materials is based on (i) the assumption that 100% of particulates will bypass the ECCS strainers, and (ii) guidance from NEI 04-07 Volume 2 Appendix V. The concentration of the post-LOCA fluid constituents is conservatively estimated based on the assumption that the IRWST 3

contains 946.4 m (250,000 gallons) of water during post-LOCA operation, which is less than the minimum 3

IRWST water volume of 993.2 m (262,388 gallons). Estimating the debris concentration at less than the expected IRWST volume yields a more concentrated debris-laden fluid for confirmatory tests, and produces conservative test results.

4.2.3 ECCS Component Evaluations This section evaluates the ECCS pumps, heat exchangers, valves, instrument tubes, and piping regarding wear, blockage, and fouling (heat exchanger).



4.2.3.1 SI and CS Pump Evaluation The SI pumps are motor-driven horizontal, multistage, centrifugal pumps with mechanical seals. The pumps are sized to deliver 3,085 L/min (815 gpm) at a discharge head of 869 m (2,850 ft). The CS pumps are motor-driven centrifugal pumps with mechanical seals. The pumps are sized to deliver 20,536 L/min (5,425 gpm) (including bypass flow 1,609 L/min (425 gpm)) at a discharge head of 125 m (410 ft). The 100% capacity design flow rate is based upon a 57.5 L/min (15.2 gpm) flow per nozzle.



The SI and CS pumps and associated mechanical seals will be qualified to operate with the post-LOCA fluids for at least 30 days, using the qualification guidance of ASME QME-1-2007 endorsed by RG1.100 Revision 3. As part of the qualification process, the pump vendor, at a minimum, will fulfill the following pump criteria:



1) Provide tests and/or analyses to confirm that the opening sizes and internal running clearances of the SI and CS pumps yield acceptable operation in post-LOCA fluids for at least 30 days. Also, provide a list of the opening sizes and internal running clearances in the qualification documentation.



2) Provide hydraulic performance test results and/or analyses to confirm that the SI and CS pumps can provide the required safety injection flow for at least 30 days of ECCS post-LOCA operation.



3) Provide tests and/or analyses to confirm that the wear rates of the SI and CS pump wetted surface materials (e.g., wear rings, pump internals, bearing, and casing) provide acceptable operation in the post-LOCA fluids for at least 30 days. Also, provide a list of the wetted pump surfaces materials, hardness of each material, and verification of acceptable wear rates in the qualification documentation.



tests or combination of tests and analyses

4) Provide mechanical performance (i.e., pump vibration, rotor dynamics, and bearing load) test results and/or analyses to confirm that there will be no adverse changes in system vibration response or rotor dynamics performance during ECCS operation for at least 30 days. Also, provide relevant test results and/or analyses to confirm that any increases in internal bypass flow caused by impeller or casing wear will not decrease the performance of the pumps or cause accelerated internal wear for at least 30 days of post-LOCA operation.



5) Provide mechanical seal assembly performance test results and/or analyses to confirm that ECCS



KEPCO & KHNP 64

RAI 63-7983_Question 06.02.02-18 Non-Proprietary Attachment (2/4)

Design Features to Address GSI-191 APR1400-E-N-NR-14001-NP, Rev.0



operation with post-LOCA fluids will not impair seal performance, or cause seal failure, or significantly degrade seal leakage during the 30 day post-LOCA mission time.

 tests or combination of tests and analyses

6) Provide test and/or analysis to confirm:

- that the cyclone separator or any filtering device designed to protect the mechanical seal, if applicable, is not susceptible to clogging or impairment by fiber or other particulates;

- that there is no adverse impact on pump performance or reliability, for at least 30 days of operation with post-LOCA fluids.



7) The vendor will also identify any additional potential pump malfunctions, per ASME QME-1-2007.



8) The vendor will verify that the SI and CS pumps provide minimum flow rates of 397 L/min (105 gpm) and 1,817 L/min (480 gpm), respectively, at shutoff head conditions.



9) The vendor will verify that SI and CS pumps provide flow rates at run-out conditions of less than 4,675 L/min (1,235 gpm) and 24,605 L/min (6,500 gpm), respectively.

4.2.3.2 Heat Exchanger Evaluation The CSHXs are used to remove heat from the containment atmosphere during and after an accident.

The units are designed to reduce the containment atmosphere pressure in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after an accident to half of the calculated peak pressure.



The CS/RHR heat exchangers are specified as shell and U-tube units. The heat exchangers are composed of 31.75 mm (1.25 inch) OD, Birmingham Wire Gauge (BWG) 18 (1.24 mm (0.049 inch)), 304 SS tubes. A single unit is provided in each of the two CSS divisions.



The heat exchanger plugging, fouling and wear evaluation are done in the context of the equipment specification. For velocity, a maximum tube velocity of 4.57 m/s (15 ft/s) is assumed. A nominal design and operating heat exchanger velocity range is 0.91 to 3.05 m/s (3 to 10 ft/s). Therefore the use of 4.57 m/s (15 ft/s) is conservative from a heat exchanger design perspective and bounds the heat exchanger design and procurement specification(s).



4.2.3.2.1 Heat Exchanger Plugging



The heat exchanger tubes are 31.75 mm (1.25 inch) OD, 29.26 mm (1.152 inch) ID, BWG 18 (1.24 mm (0.049 inch)). The perforated plate hole size of the IRWST sump strainers is 2.38 mm (0.094 inch). The heat exchanger tubes are significantly larger than the largest expected particle size. Therefore, a heat exchanger tube will not be plugged or blocked by post-LOCA debris. The flow velocity within a heat exchanger tube is significantly greater than the terminal settling velocity of the debris (Table 4.2-4).

Therefore, the debris will not settle in the heat exchanger tubes.



These conclusions are consistent with the referenced NRC Safety Evaluation on WCAP-16406-P



KEPCO & KHNP 65

RAI 63-7983_Question 06.02.02-18 Non-Proprietary Attachment (3/4)

Design Features to Address GSI-191 APR1400-E-N-NR-14001-NP, Rev.0



(Reference [4-3]).







4.2.3.2.2 Heat Exchanger Performance and Wear



2 2 The CS heat exchange is sized and designed with a fouling factor of 0.000088 m -K/W (0.0005 hr-ft -

°F/Btu) to maximize heat transfer efficiency and performance. The post-LOCA fluid could potentially cause particulate fouling of the heat exchanger tubes if the fluid velocity is less than the terminal settling velocity of the debris. However, fouling is considered a long-term phenomenon. In addition, the heat load of the CS heat exchangers is greatest at the start of the event and decreases rapidly over the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Heat removal capacity is not degraded over this short period. Any potential reduction in capability over the 30 day mission time is gradual and well within the nominal heat exchanger design.



The CS heat exchanger tubes are specified to be constructed of 304 stainless steel. Stainless steel is appropriate for use as heat exchanger tubing and is standard for use in mildly abrasive applications. The tube material will not significantly degrade considering operation with post-LOCA fluid over an intended mission time of 30 days.



Therefore, the CS heat exchanges are fully capable of performing their intended function using post-LOCA fluid as the process fluid.

tests or combination of tests and analyses



The vendor will also provide test and/or analysis to confirm that the heat exchanger tube material will not degrade significantly (i.e., eroded tube thickness > minimum tube thickness required to retain pressure) in post-LOCA fluid over the 30 day mission time.



4.2.3.3 Evaluation of Valves, Orifices and Pipes 4.2.3.3.1 Blockage and Debris Settling Evaluation for Valves, Orifices and Pipes The strainer hole size is 2.38 mm (0.094 inch). Therefore, when the gap of the components is 2.38 mm (0.094 inch) + 0.238 mm (0.0094 inch) (10%) or 2.62 mm (0.103 inch) or less than this value, the flow-path or component may be blocked. This is consistent with Reference [4-3]. Components that are in the flow-paths during accidents are listed in Table 4.2-1.



Piping



Fluid velocity decreases with an increase in pipe diameter. Therefore, the lowest velocity in the ECCS occurs in the region with the largest pipe diameter/flow area. Flow velocities in all piping except several cases (24 inch, 20 inch, and 10 inch SI Pump suction lines and 12 inch SI pump discharge line) are above the settling velocities of the post-LOCA fluid. Refer to Table 4.2-6.





KEPCO & KHNP 66

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Design Features to Address GSI-191 APR1400-E-N-NR-14001-NP, Rev.0



through the sump strainer. Therefore the valves do not clog due to post-LOCA insulation debris.

4) Orifice



ECCS and CSS flow is controlled though a combination of orifices and throttled valves. Orifices are used for throttling system flow. ECCS and CSS pressure and flow are monitored in the MCR.

The orifice sizes are above 20.3 mm (0.8 inch). Flow velocities in all cases are above the settling velocities of the post-LOCA fluid (Table 4.2-6). Therefore, the potential of orifice plugging is very low.

5) Spray Nozzles



The containment main spray nozzles and auxiliary spray nozzles has an orifice of 13.1 mm (0.516 inch) and 5.6 mm (0.22 inch) diameter, respectively. This orifice is the smallest portion of spray nozzle. The strainer hole size is 2.38 mm (0.094 inch). Containment spray nozzles are significantly larger than the strainer hole size. Their one-piece design provides a large, unobstructed flow passage that resists clogging by particles. Therefore, the potential of spray nozzle plugging is very low.

4.2.3.3.2 Wear Rate Evaluation for Valves, Orifices and Pipes Erosive wear is caused by particles that impinge on a component surface and remove material from the surface because of momentum effects. The wear rate of a material depends on the debris type, debris concentration, material hardness, flow velocity, and valve position.



Flow rates of 6,057 L/min (1,600 gpm) and 26,963 L/min (7,123 gpm)) for SIS and CSS, respectively, are conservatively assumed for the wear rate evaluation of the components listed in Table 4.2-1. The ECCS design flow rates listed in Table 4.2-1 include the maximum flow rate of the SI pump, CS pump, and the sum of the SIS and CSS flows based on system configuration.



Table 4.2-7 contains a summary of the piping and orifice wear calculation. Based upon the results of wear evaluation for piping and orifice, it is concluded that the system piping and component flow resistances will change minimally during the course of the LOCA. Therefore, flow balances and system performance are not affected in an appreciable manner. The resulting flows and pressures are consistent or conservative with respect to the accident analysis. The minor resistance changes do not affect the system flow calculations and design basis analysis.



The wear rate of ECCS valves will be provided by the vendor. The vendor will qualify the ECCS valves to operate with the post-LOCA fluids for at least 30 days, using the qualification guidance of ASME QME-1-2007 endorsed by RG1.100 Revision 3. As part of the qualification process, the vendor will provide data and/or analyses to support acceptable wear rates during operation in post-LOCA fluids (Table 4.2-5) at the associated flow velocities listed in Table 4.2-6.

 tests or combination of tests and analyses Vendor(s) will also provide tests and/or analyses to support acceptable wear rates of pipes and orifices.

In addition, an analysis will be provided to confirm that the overall system resistance/pressure drop across the ECCS is consistent with the safety analysis results for the 30 day mission time.



For conservatism, vendors will perform component wear evaluations at the assumed flow rates/velocities.



KEPCO & KHNP 68

06.02.02 1 / 2 KEPCO/KHNP RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION APR1400 Design Certification Korea Electric Power Corporation / Korea Hydro & Nuclear Power Co., LTD Docket No.52-046 RAI No.: 63-7983 SRP Section: 06.02.02 - Containment Heat Removal Systems Application Section: 6.2.2 Date of RAI Issue: 07/07/2015 Question No. 06.02.02-19 Technical Report APR1400-E-N-NR-14001-P, Section 4.2.3.2.1, Heat Exchanger Plugging, states that the flow velocity through the heat exchanger tubes is significantly greater than the terminal settling velocity of the debris. Therefore, the applicant concludes that debris will not settle in the heat exchanger tubes. However, the Technical Report does not specify the minimum flow velocity through the heat exchanger tubes. To provide assurance that debris settling will not occur in the heat exchanger tubes, the NRC staff requests that the applicant specify the minimum flow velocity through the heat exchanger tubes in the technical report.

Response

The heat exchanger is designed with a tube flow velocity not to be less than 3 ft/sec to prevent deposition of suspended materials in accordance with the EPRI URD. Therefore, the flow velocity through the heat exchanger tubes is significantly greater than the terminal settling velocity of the debris and debris will not settle in the heat exchanger tubes.

The design information for the minimum flow velocity through the heat exchanger tubes will be added in the technical report.

Impact on DCD There is no impact on the DCD.

Impact on PRA There is no impact on the PRA.

06.02.02 2 / 2 KEPCO/KHNP Impact on Technical Specifications There is no impact on the Technical Specifications.

Impact on Technical/Topical/Environmental Reports Technical Report APR1400-E-N-NR-14001-P/NP, Section 4.2.3.2.1 will be revised as indicated in the attached markup.

RAI 63-7983_Question 06.02.02-19 Non-Proprietary Attachment (1/1)

Design Features to Address GSI-191 APR1400-E-N-NR-14001-NP, Rev.0



operation with post-LOCA fluids will not impair seal performance, or cause seal failure, or significantly degrade seal leakage during the 30 day post-LOCA mission time.



6) Provide test and/or analysis to confirm:

- that the cyclone separator or any filtering device designed to protect the mechanical seal, if applicable, is not susceptible to clogging or impairment by fiber or other particulates;

- that there is no adverse impact on pump performance or reliability, for at least 30 days of operation with post-LOCA fluids.



7) The vendor will also identify any additional potential pump malfunctions, per ASME QME-1-2007.



8) The vendor will verify that the SI and CS pumps provide minimum flow rates of 397 L/min (105 gpm) and 1,817 L/min (480 gpm), respectively, at shutoff head conditions.



9) The vendor will verify that SI and CS pumps provide flow rates at run-out conditions of less than 4,675 L/min (1,235 gpm) and 24,605 L/min (6,500 gpm), respectively.

4.2.3.2 Heat Exchanger Evaluation The CSHXs are used to remove heat from the containment atmosphere during and after an accident.

The units are designed to reduce the containment atmosphere pressure in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after an accident to half of the calculated peak pressure.



The CS/RHR heat exchangers are specified as shell and U-tube units. The heat exchangers are composed of 31.75 mm (1.25 inch) OD, Birmingham Wire Gauge (BWG) 18 (1.24 mm (0.049 inch)), 304 SS tubes. A single unit is provided in each of the two CSS divisions.



The heat exchanger plugging, fouling and wear evaluation are done in the context of the equipment specification. For velocity, a maximum tube velocity of 4.57 m/s (15 ft/s) is assumed. A nominal design and operating heat exchanger velocity range is 0.91 to 3.05 m/s (3 to 10 ft/s). Therefore the use of 4.57 m/s (15 ft/s) is conservative from a heat exchanger design perspective and bounds the heat exchanger design and procurement specification(s).

 because the heat exchanger is designed with a tube flow velocity not to be less than 3 ft/s to prevent 4.2.3.2.1 Heat Exchanger Plugging deposition of suspended materials in transition areas of heat exchangers, piping, etc.



The heat exchanger tubes are 31.75 mm (1.25 inch) OD, 29.26 mm (1.152 inch) ID, BWG 18 (1.24 mm (0.049 inch)). The perforated plate hole size of the IRWST sump strainers is 2.38 mm (0.094 inch). The heat exchanger tubes are significantly larger than the largest expected particle size. Therefore, a heat exchanger tube will not be plugged or blocked by post-LOCA debris. The flow velocity within a heat exchanger tube is significantly greater than the terminal settling velocity of the debris (Table 4.2-4).

Therefore, the debris will not settle in the heat exchanger tubes.



These conclusions are consistent with the referenced NRC Safety Evaluation on WCAP-16406-P



KEPCO & KHNP 65

06.02.02 1 / 2 KEPCO/KHNP RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION APR1400 Design Certification Korea Electric Power Corporation / Korea Hydro & Nuclear Power Co., LTD Docket No.52-046 RAI No.: 63-7983 SRP Section: 06.02.02 - Containment Heat Removal Systems Application Section: 6.2.2 Date of RAI Issue: 07/07/2015 Question No. 06.02.02-23 Review procedure #9 of SRP 6.2.2, Containment Heat Removal Systems, addresses performance evaluations for equipment downstream of the IRWST sump strainer with regard to debris ingestion. To complete this review, additional information is needed. Technical Report APR1400-E-N-NR-14001-P, Section 4.2.3.3.1 addresses debris settling evaluation for valves (including gates valves, check valves and globe valves). For gate and check valves, the applicant states that the flow velocities in all cases are above the settling velocities and, therefore, these valves are not expected to clog because of post-LOCA insulation debris.

However, for globe valves, the applicant does not address flow velocity being above the settling velocity. Therefore, the NRC staff requests that the applicant address debris settling in globe valves in the technical report.

Response

Globe valves control ECCS and CSS flow by the throttling of the valve opening. Flow velocity decreases with an increase in valve opening and the lowest velocity is at the full open. The lowest flow velocities in all globe valves are above the settling velocity of the post-LOCA fluid.

The statement Flow velocities in all cases are above the settling velocities of the post-LOCA fluid (refer to Table 4.2-6) will be added in the technical report.

Impact on DCD There is no impact on the DCD.

06.02.02 2 / 2 KEPCO/KHNP Impact on PRA There is no impact on the PRA.

Impact on Technical Specifications There is no impact on the Technical Specifications.

Impact on Technical/Topical/Environmental Reports Technical Report APR1400-E-N-NR-14001-P/NP, Section 4.2.3.3.1 will be revised as indicated in the attached markup.

RAI 63-7983_Question 06.02.02-23 Non-Proprietary Attachment (1/1)

Design Features to Address GSI-191 APR1400-E-N-NR-14001-NP, Rev.0



The SI pump suction line is a 24-inch Schedule 80 stainless steel pipe (ID = 547.7 mm (21.562 inch)).

The velocity in this line at the minimum flow rate is 0.13 m/s (0.43 ft/s). This velocity is less than the terminal settling velocities of the post-LOCA debris materials (Table 4.2-4). Therefore, settling will occur in the SI flow path to the RCS.



The CS pump suction line is a 16-inch Schedule 80 stainless steel pipe (ID = 363.5 mm (14.312 inch)).

The velocity in this line at the minimum flow rate is 0.25 m/s (0.82 ft/s). This velocity is greater than the terminal settling velocities of the post-LOCA debris materials (Table 4.2-4). Therefore, settling will not occur in the CS flow path to the containment.



Debris settling is a longer term phenomena and has no short term impact on flow. Therefore, the potential of piping plugging or blockage and its impact on system operation is very low. Reliability of the SIS is considered in the design, procurement, and installation/layout of components.









Valves The valve types that are used in the flow-path during an accident are gate, check, globe and butterfly valves, see Table 4.2-1.

1) Gate valves Gate valves are used full-open or full-close. The gate valve sizes are above 101.6 mm (4 inch)

(see Table 4.2-1). Flow velocities in all cases are above the settling velocities of the post-LOCA fluid (refer to Table 4.2-6). NUREG/CR-6902 (Reference [4-4]) states that valve openings significantly larger than the debris size will not clog. The strainer hole size is 2.38 mm (0.094 inch).

The 101.6 mm (4 inch) valve opening is considerably larger than any expected particle passing through the sump strainer. Therefore, the valves do not clog due to post-LOCA insulation debris.

2) Check valves



Check valves are used with sufficient flow rate, and check valve sizes are above 101.6 mm (4 inch)

(see Table 4.2-6). Flow velocities in all cases are above the settling velocities of the post-LOCA fluid (refer to Table 4.2-6). Reference [4-4] states that valve openings significantly larger than the debris size will not be clogged. The strainer hole size is 2.38 mm (0.094 inch). The 101.6 mm (4 inch) valve opening is considerably larger than any expected particle passing through the sump strainer. Therefore, the valves do not clog due to post-LOCA insulation debris.

3) Globe valves Flow velocities in all cases are above the settling velocities of the post-LOCA fluid (refer to Table 4.2-6).

ECCS and CSS flow is controlled though a combination of orifices and throttled valves. Globe valves normally are full open but may be used for throttling system flow. ECCS and CSS pressure and flow are monitored in the MCR. In general, if a globe valve is in a throttled position and it begins to clog, system flow will decrease. Operator action may be taken to open the valve, thus clearing the potential clog. In the APR1400, globe valve sizes are above 101.6 mm (4 inch) (see Table 4.2-1). Reference [4-4] states that valve openings significantly larger than the debris size will not be clogged. The strainer hole size is 2.38 mm (0.094 inch). Throttle valves are expected to be throttled to a minimum of 50.8 mm (2 inch) open between the valve disc and seat.

The 50.8 mm (2 inch) valve opening is considerably larger than any expected particle passing



KEPCO & KHNP 67

06.02.02 1 / 1 KEPCO/KHNP RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION APR1400 Design Certification Korea Electric Power Corporation / Korea Hydro & Nuclear Power Co., LTD Docket No.52-046 RAI No.: 63-7983 SRP Section: 06.02.02 - Containment Heat Removal Systems Application Section: 6.2.2 Date of RAI Issue: 07/07/2015 Question No. 06.02.02-25 Technical Report APR1400-E-N-NR-14001-P, Section 4.2.3.3.2, Wear Rate Evaluation for Valves, Orifices and Pipes, states that the wear rate of ECCS (SIS) valves will be provided by the vendor and describes the qualification process. This section does not address CSS valve qualification. The staff requests that the applicant address CSS valve qualification in the technical report.

Response

The CSS valve qualification will also be performed by the vendor and will be incorporated in the technical report.

Impact on DCD There is no impact on the DCD.

Impact on PRA There is no impact on the PRA.

Impact on Technical Specifications There is no impact on the Technical Specifications.

Impact on Technical/Topical/Environmental Reports Technical Report APR1400-E-N-NR-14001-P/NP, Section 4.2.3.3.2 will be revised as indicated in the attached markup.

RAI 63-7983_Question 06.02.02-25 Non-Proprietary Attachment (1/1)

Design Features to Address GSI-191 APR1400-E-N-NR-14001-NP, Rev.0



through the sump strainer. Therefore the valves do not clog due to post-LOCA insulation debris.

4) Orifice



ECCS and CSS flow is controlled though a combination of orifices and throttled valves. Orifices are used for throttling system flow. ECCS and CSS pressure and flow are monitored in the MCR.

The orifice sizes are above 20.3 mm (0.8 inch). Flow velocities in all cases are above the settling velocities of the post-LOCA fluid (Table 4.2-6). Therefore, the potential of orifice plugging is very low.

5) Spray Nozzles



The containment main spray nozzles and auxiliary spray nozzles has an orifice of 13.1 mm (0.516 inch) and 5.6 mm (0.22 inch) diameter, respectively. This orifice is the smallest portion of spray nozzle. The strainer hole size is 2.38 mm (0.094 inch). Containment spray nozzles are significantly larger than the strainer hole size. Their one-piece design provides a large, unobstructed flow passage that resists clogging by particles. Therefore, the potential of spray nozzle plugging is very low.

4.2.3.3.2 Wear Rate Evaluation for Valves, Orifices and Pipes Erosive wear is caused by particles that impinge on a component surface and remove material from the surface because of momentum effects. The wear rate of a material depends on the debris type, debris concentration, material hardness, flow velocity, and valve position.

and CSS



Flow rates of 6,057 L/min (1,600 gpm) and 26,963 L/min (7,123 gpm)) for SIS and CSS, respectively, are conservatively assumed for the wear rate evaluation of the components listed in Table 4.2-1. The ECCS design flow rates listed in Table 4.2-1 include the maximum flow rate of the SI pump, CS pump, and the sum of the SIS and CSS flows based on system configuration.



Table 4.2-7 contains a summary of the piping and orifice wear calculation. Based upon the results of wear evaluation for piping and orifice, it is concluded that the system piping and component flow resistances will change minimally during the course of the LOCA. Therefore, flow balances and system performance are not affected in an appreciable manner. The resulting flows and pressures are consistent or conservative with respect to the accident analysis. The minor resistance changes do not affect the system flow calculations and design basis analysis.

 and CSS and CSS The wear rate of ECCS valves will be provided by the vendor. The vendor will qualify the ECCS valves to operate with the post-LOCA fluids for at least 30 days, using the qualification guidance of ASME QME-1-2007 endorsed by RG1.100 Revision 3. As part of the qualification process, the vendor will provide data and/or analyses to support acceptable wear rates during operation in post-LOCA fluids (Table 4.2-5) at the associated flow velocities listed in Table 4.2-6.



Vendor(s) will also provide tests and/or analyses to support acceptable wear rates of pipes and orifices.

In addition, an analysis will be provided to confirm that the overall system resistance/pressure drop across the ECCS is consistent with the safety analysis results for the 30 day mission time.

 and CSS For conservatism, vendors will perform component wear evaluations at the assumed flow rates/velocities.



KEPCO & KHNP 68

06.02.02 1 / 2 KEPCO/KHNP RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION APR1400 Design Certification Korea Electric Power Corporation / Korea Hydro & Nuclear Power Co., LTD Docket No.52-046 RAI No.: 63-7983 SRP Section: 06.02.02 - Containment Heat Removal Systems Application Section: 6.2.2 Date of RAI Issue: 07/07/2015 Question No. 06.02.02-27 Technical Report APR1400-E-N-NR-14001-P, Section 4.2.3.4, Instrument Tubing Clogging Evaluation, states that when the instrument tubing lines maintain a solid state prior to emergency core cooling operation, it is determined that tubing integrity is not affected because there is almost no possibility of debris ingestion, and the evaluation shows there are no effects from flow blockage and wear because flow velocities in all cases are above the settling velocities of the post-LOCA fluid. Also, all instrument connections used in the APR1400 reactor are located either at the horizontal or above. The NRC staff requests that the applicant specify in the technical report that all instrument connections are at the side or at the top of the pipe and confirm that the SIS and CSS systems do not contain any bottom-mounted instrument connections.

Response

As described in Section 4.2.3.4, all instrument connections used in the APR1400 reactor are located either at the horizontal or above. This means that all instrument connections are at the side or at the top of the pipe and there are no bottom-mounted instrument connections in the SIS and CSS.

To clarify the instrument connection locations, the technical report will be revised to reflect the statement requested by the NRC staff.

Impact on DCD There is no impact on the DCD.

06.02.02 2 / 2 KEPCO/KHNP Impact on PRA There is no impact on the PRA.

Impact on Technical Specifications There is no impact on the Technical Specifications.

Impact on Technical/Topical/Environmental Reports Technical Report APR1400-E-N-NR-14001-P/NP, Section 4.2.3.4 will be revised as indicated in the attached markup.

RAI 63-7983_Question 06.02.02-27 Non-Proprietary Attachment (1/1)

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4.2.3.4 Instrument Tubing Clogging Evaluation According to WCAP-16406-P (Reference [4-3]), when the instrument tubing lines maintain a solid state prior to emergency core cooling operation, it is determined tubing integrity is not affected because there is almost no possibility of debris ingestion, and the evaluation shows there are no effects from flow blockage and wear because flow velocities in all cases are above the settling velocities of the post-LOCA fluid.

Also, all instrument connections used in the APR1400 are located either at the horizontal or above.

 all instrument connections are at the side or at the top of the pipe and the SIS and CSS do not contain any bottom-mounted instrument connections.

4.2.3.5 Chemical Effects Evaluation Chemical precipitates (aluminum oxy-hydroxide, sodium aluminum silicate and calcium phosphate) are formed when concrete and LOCA-generated debris materials are exposed to the buffering materials in the IRWST. This reaction forms additional solid species that could potentially pass through the sump screen and degrade the performance of the ECCS.



In-vessel fuel blockage tests performed using particulate, fiber and aluminum oxy-hydroxide precipitate demonstrate that the flow resistance created by the chemical precipitate is significantly less than the pump head that is available in the ECCS piping system. Secondly, similar to the particulate and fiber debris materials, only chemical precipitates smaller than (or equal to) the perforated plate hole size of IRWST sump strainer will be ingested by the ECCS. The diameter of the ECCS piping, orifices, valves and heat exchanger tubes are significantly larger than the size of the ingested chemical precipitates, and the velocity of the post-LOCA fluid is expected to be sufficient to avoid settling. Therefore, components downstream of the sump strainers are not expected to become clogged with chemical precipitates such that blockage of flow occurs.



In addition, the qualification of the ECCS pumps, performed with conservative amounts of post-LOCA debris (Table 4.2-5), in accordance with ASME QME-1-2007, will include confirmation that the internal running clearance of the ECCS pumps is sufficiently large enough to avoid clogging, and supports acceptable pump and seal operation during the 30-day post-LOCA mission time.



The chemical precipitates are also unlikely to reduce the efficiency of the heat exchanger because most precipitates will form later in the post-LOCA event when temperatures have decreased ((NUREG/CR-6913 (Reference [4-5]) and NUREG/CR-6914 (Reference [4-6])) and when the required heat transfer capacity of the ECCS heat exchangers has ample margin. Precipitates that form soon after the pipe break are only expected to form, at most, thin deposit films on the heat exchanger tubes. Deposit thicknesses are limited by scrubbing from particulate in the coolant as well as the relatively high flow rate and pressure differential associated with the ECCS. In addition, the CS heat exchangers are designed and specified with conservative fouling factors to maximize heat transfer efficiency and performance. Operating experience has also demonstrated that fouling is a long-term phenomenon and heat exchangers can still perform adequately with significant fouling. Therefore, the chemical precipitates are not expected to significantly impair the heat transfer capability of the CS heat exchangers.



4.2.4 Evaluation Summary The intent of this section is to assess the downstream effects of ECCS and CSS of the APR1400 under



KEPCO & KHNP 69

06.02.02 1 / 1 KEPCO/KHNP RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION APR1400 Design Certification Korea Electric Power Corporation / Korea Hydro & Nuclear Power Co., LTD Docket No.52-046 RAI No.: 63-7983 SRP Section: 06.02.02 - Containment Heat Removal Systems Application Section: 6.2.2 Date of RAI Issue: 07/07/2015 Question No. 06.02.02-30 APR1400 DCD Tier 1, Table 2.11.2-4, Containment Spray System ITAAC, does not contain an ITAAC to confirm the functional qualification of the CSS pumps similar to ITAAC 9.b in APR1400 DCD Tier 1, Table 2.4.3-4, Safety Injection System ITAAC, for the SIS pumps. The NRC staff requests that the APR1400 design certification applicant specify its plans to update DCD Tier 1, Table 2.11.2-4, to include ITAAC for the functional qualification of CSS pumps.

Response

An ITAAC to confirm the functional qualification of the CSS pumps will be added.

Impact on DCD In DCD Tier 1, Section 2.11.2.1 and Table 2.11.2-4 will be revised as indicated in the attached markup.

Impact on PRA There is no impact on the PRA.

Impact on Technical Specifications There is no impact on the Technical Specifications.

Impact on Technical/Topical/Environmental Reports There is no impact on any Technical, Topical, or Environmental Report.

RAI 63-7983_Question 06.02.02-30 Attachment (1/2)

$35 '&' 7,(5 

10. The CSS pumps have sufficient net positive suction head (NPSH).
11. The CSS has heat removal capacity to control the containment atmosphere temperature and pressure.
12. The moderate-energy piping systems are reconciled with pipe rupture hazards analyses report to ensure that the safety-related SSCs are protected against or are qualified to withstand the environmental effects associated with postulate failures of these piping systems.

2.11.2.2 Inspections, Tests, Analyses, and Acceptance Criteria The inspection, tests, analyses, and associated acceptance criteria for the CSS are specified in Table 2.11.2-4.

The ITAAC related to the CIVs and the piping between the CIVs of the CSS are described in Table 2.11.3-2.

13. The pumps identified in Table 2.11.2-2 can perform their safety functions under expected ranges of fluid flow, pump head, electrical conditions, and temperature conditions up to and including design-basis conditions.

2.11-7 Rev. 0

RAI 63-7983_Question 06.02.02-30 Attachment (2/2)

$35 '&' 7,(5 

Table 2.11.2-4 (6 of 6)

Design Commitment Inspections, Tests, Analyses Acceptance Criteria

11. The CSS has heat removal 11.a Analyses will be performed to 11.a A report exists and capacity to control the determine the heat removal concludes that the product containment atmosphere capacities of the as-built CS of the overall heat transfer temperature and pressure. heat exchanger. coefficient and the effective heat transfer area, UA, of each CS heat exchanger identified in Table 2.11.2-2 is greater than or equal to 7.793 x 105 cal/hr-°C (1.718 x 106 Btu/hr-°F).

11.b A test of the as-built CS pump 11.b The as-built CS pump will be performed to measure identified in Table 2.11.2-2 the flow rate to the CS heat delivers at least 18,927 exchanger. L/min (5,000 gpm) to the CS heat exchanger.

12. The moderate-energy piping 12. Inspections and analyses of the 12. Pipe rupture hazard analysis systems are reconciled with as-built moderate-energy piping report exits and concludes pipe rupture hazards analyses and safety-related SSCs will be that the as-built safety-report to ensure that the performed. related SSCs are protected safety-related SSCs are against or are qualified to protected against or are withstand the effects of qualified to withstand the postulated pipe failures of environmental effects the as-built moderate-associated with postulate energy piping system.

failures of these piping systems.

13. The pumps identified 13.a Type tests or a 13.a A report exists and in Table 2.11.2-2 can combination of type tests concludes that the pumps perform their safety and analyses of each pump identified in Table 2.11.2-2 functions under expected identified in Table 2.11.2-2 can perform their safety ranges of fluid flow, pump will be performed to functions under expected head, electrical conditions, demonstrate the ability of the ranges of fluid flow, pump and temperature pump to perform its safety head, electrical conditions, conditions up to and function under expected and temperature including design-basis ranges of fluid flow, pump conditions up to and conditions. head, electrical conditions, including design-basis and temperature conditions conditions.

up to and including design- 13.b Each as-built pump basis conditions. identified in Table 2.11.2-2 13.b Inspections will be is bounded by the type performed of each as-built tests, or a combination of pump identified2.11-17inTable type tests and analyses. Rev. 0 2.11.2-2.

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