response to request for additional information · nrc rg 1.189 (reference 8) is used as guidance...

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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.: 29-7926

SRP Section: 03.02.01 – Seismic Classification

Application Section: 3.2.1

Date of RAI Issue: 06/15/2015

Question No. 03.02.01-1

SRP 3.2.1 Review Procedure 1 indicates that the staff review should establish whether the applicant’s classification system conforms with Regulatory Guides 1.29, 1.143, 1.151, and 1.189. A statement regarding conformance with these RGs is necessary to make a safety finding under SRP 3.2.1. The applicant has referred to these RGs as guidance, but has not committed to conformance. Please revise the DCD to specify conformance with the RGs, or indicate where deviations from the guidance are taken and justify these deviations.

Response

DCD Tier 2, subsection 3.2.1 will be revised to specify conformance with Regulatory Guides 1.29, 1.143, 1.151, and 1.189.

Impact on DCD

DCD Tier 2, subsection 3.2.1 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.

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APR1400 DCD TIER 2

3.2-2

3.2.1 Seismic Classification

General Design Criterion (GDC) 2 (Reference 1) requires, in part, that nuclear power plant SSCs important to safety be designed to withstand the effects of earthquakes without loss of capability to perform their safety function. Plant features, including foundations and supports, that are designed to remain functional in the event of a safe shutdown earthquake (SSE) or surface deformation are designed as seismic Category I. These plant features are the features that are necessary to provide reasonable assurance of (1) the integrity of the reactor coolant pressure boundary (RCPB), (2) the capability to shut down the reactor and maintain it in a safe shutdown condition, or (3) the capability to prevent or mitigate the consequences of accidents that could result in potential offsite exposures comparable to the guideline exposures of 10 CFR 50.34(a)(1) and 10 CFR 52.79 or 10 CFR 100.11 (Reference 2).

The earthquake for which these plant features are designed is defined as the SSE in 10 CFR Part 100, Appendix A (Reference 3), and 10 CFR Part 50, Appendix S (Reference 4). The SSE is based on an evaluation of the maximum earthquake potential and produces the maximum vibratory ground motion for which SSCs important to safety are designed to remain functional.

NRC Regulatory Guide (RG) 1.29 (Reference 5) is used as guidance to identify seismic Category I SSCs to fulfill the requirements of GDC 2.

NRC RG 1.143 (Reference 6) is used as guidance for the seismic design and classification for radioactive waste management SSCs. Radioactive waste management SSCs are designed to meet the design basis loads including natural phenomena and internal/external man-induced hazard design criteria in accordance with NRC RG 1.143. Designing and constructing radioactive waste management SSCs to meet the requirements of GDC 61 and the guidance on seismic design and classification in NRC RG 1.143 provide reasonable assurance that SSCs that contain radioactivity are properly classified and that radiation exposure as a result of a seismic event will be as low as is reasonably achievable (ALARA) The radwaste safety classification is described in Table 3.2-1.

NRC RG 1.151 (Reference 7) is used as guidance for the seismic classification of safety-related instrumentation sensing lines and their supports. Compliance with Positions C.2 and C.3 of NRC RG 1.151 provides reasonable assurance that the instrument sensing lines

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The seismic classification used in APR1400 complies with the seismic criteria stated in NRC RG 1.29 to meet the requirements of both GDC 2 and 10 CFR Part 50, Appendix S.

Radioactive waste management SSCs comply with the seismic design criteria specified in NRC RG 1.143 (Reference 6).

Instrument sensing lines and their supports are designed in accordance with the seismic design criteria of NRC RG 1.151 (Reference 7).

RAI 29-7926 - Question 03.02.01-1 Attachment (1/2)

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APR1400 DCD TIER 2

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used to actuate or monitor safety-related systems are appropriately classified and will be capable of withstanding the effects of the SSE.

NRC RG 1.189 (Reference 8) is used as guidance for the seismic classification of fire protection systems. Compliance with Positions 3.2.1, 6.1.1.2, and 7.1 of NRC RG 1.189 provides reasonable assurance that the SSCs important to safety that are required to function during an SSE are properly classified as seismic Category I, will function during such events, and will provide reasonable assurance that the safety functions can be performed.

Seismic categories are designated as seismic Category I, II, or III. Seismic Category III is the equivalent of the non-seismic (NS) category specified in NRC RG 1.29.

The seismic categories of SSCs are listed in Table 3.2-1. The COL applicant is to identify the seismic classification of site-specific SSCs that are to be designed to withstand the effects of an SSE (COL 3.2(1)).

The seismic category portions of SSCs are indicated by the class breaks shown on the flow diagrams for the appropriate systems described in this DCD. Seismic Category I requirements extend to the first seismic anchor beyond the interface of the classification change. Supports for piping and components have the same seismic classifications as the piping and components that are supported.

Seismic Category I, II, and III (NS) SSCs are defined as follows:

a. Seismic Category I

SSCs that are important to safety and designed to remain functional in the event of an SSE are designated as seismic Category I.

The selection of seismic Category I SSCs is in accordance with the definition above and the guidance provided by NRC RG 1.29 (Reference 5). Seismic Category I components have a designated safety class in accordance with ANSI/ANS 51.1-1983 (Reference 9; see Subsection 3.2.3). All components in Safety Classes 1, 2, and 3 are seismic Category I. The portions of SSCs that

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Fire protection systems are designed in accordance with the seismic design criteria of NRC RG 1.189 (Reference 8).


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RAI No.: 29-7926





RG 1.29 defines seismic Category I in Regulatory Position C.1. In doing so, the RG creates two categories of SSCs: those that are seismic Category I and those that are not (non-seismic Category I).

The applicant has created three seismic categories: seismic Category I, which conforms with Regulatory Position C.1, and two other categories. The applicant has defined seismic Category II similarly to RG 1.29, Regulatory Position C.2. Seismic Category III is defined as “anything not seismic Category I or II” on DCD Tier 2, Section 3.2.1, page 3.2-5, but this is not consistent with the statement on page 3.2-3, defining it as “the equivalent of the non-seismic (NS) category specified in NRC RG 1.29.”

RG 1.29 does not define a “non-seismic (NS) category.” Please revise the definition of Seismic Category III on DCD Tier 2, page 3.2-3 to clarify what is meant by this statement in terms consistent with RG 1.29.

Response

Since the term of “non-seismic (NS) category” is not defined in Regulatory Guide 1.29, the term and abbreviation will be deleted from DCD Tier 2, subsection 3.2.1.

Impact on DCD

DCD Tier 2, subsection 3.2.1 will be revised as indicated in the attached markup.

Impact on PRA


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APR1400 DCD TIER 2

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used to actuate or monitor safety-related systems are appropriately classified and will be capable of withstanding the effects of the SSE.

NRC RG 1.189 (Reference 8) is used as guidance for the seismic classification of fire protection systems. Compliance with Positions 3.2.1, 6.1.1.2, and 7.1 of NRC RG 1.189 provides reasonable assurance that the SSCs important to safety that are required to function during an SSE are properly classified as seismic Category I, will function during such events, and will provide reasonable assurance that the safety functions can be performed.

Seismic categories are designated as seismic Category I, II, or III. Seismic Category III is the equivalent of the non-seismic (NS) category specified in NRC RG 1.29.

The seismic categories of SSCs are listed in Table 3.2-1. The COL applicant is to identify the seismic classification of site-specific SSCs that are to be designed to withstand the effects of an SSE (COL 3.2(1)).

The seismic category portions of SSCs are indicated by the class breaks shown on the flow diagrams for the appropriate systems described in this DCD. Seismic Category I requirements extend to the first seismic anchor beyond the interface of the classification change. Supports for piping and components have the same seismic classifications as the piping and components that are supported.

Seismic Category I, II, and III (NS) SSCs are defined as follows:

a. Seismic Category I

SSCs that are important to safety and designed to remain functional in the event of an SSE are designated as seismic Category I.

The selection of seismic Category I SSCs is in accordance with the definition above and the guidance provided by NRC RG 1.29 (Reference 5). Seismic Category I components have a designated safety class in accordance with ANSI/ANS 51.1-1983 (Reference 9; see Subsection 3.2.3). All components in Safety Classes 1, 2, and 3 are seismic Category I. The portions of SSCs that

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APR1400 DCD TIER 2

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form an interface between seismic Category I and seismic Category II/III (or NS) features are designed to seismic Category I requirements in accordance with Regulatory Position C.3 of NRC RG 1.29 (Reference 5). Seismic Category I design requirements extend to the first seismic anchor (restraint) beyond the defined boundaries.

Portions of some non-safety-related systems (e.g., fire protection system) are classified as seismic Category I to conform with NRC RG 1.189.

Seismic Category I SSCs are designed to remain functional and within the applicable stress and deformation limits (elastic range of material properties) when subjected to the effects of the vibratory motion of the operating basis earthquake (OBE) in combination with normal operation loads. This design is based on the design for SSE loads where an OBE is defined as one third of the SSE, as described in Subsection 3.7.1.1. Seismic Category I structures are protected from interaction with adjacent non-seismic structures, as described in Subsection 3.7.2.8. The seismic classifications of platforms and miscellaneous steel located in seismic Category I application are described in Subsection 3.8.3.

Seismic Category I SSCs meet the QA requirements of 10 CFR Part 50, Appendix B (Reference 10). The criteria used for the design of seismic Category I SSCs are described in Section 3.7.

b. Seismic Category II

SSCs that do not perform a nuclear safety-related function and whose continued function is not required are classified as non-nuclear safety (NNS) (see Subsection 3.2.3).

NNS SSCs that are not seismic Category I but whose failure by virtue of physical proximity to safety-related equipment or structures could prevent a component or structure from fulfilling its required function are classified as seismic Category II.

NNS SSCs are designed to preclude a gross structural failure resulting from an SSE that could degrade the ability of an adjacent safety-related SSC to function to

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APR1400 DCD TIER 2

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an unacceptable level or result in incapacitating injuries to personnel in the main control room (MCR).

Seismic Category II SSCs meet the augmented quality assurance requirements for non-safety-related SSCs as described in Section 17.5.

c. Seismic Category III (NS)

All SSCs not covered by seismic Category I or II are classified as seismic Category III (NS) and are designed in accordance with industry codes and standards as applicable for their design function.

3.2.2 System Quality Group Classification

GDC 1 of 10 CFR Part 50 Appendix A (Reference 1) requires that nuclear power plant systems and components important to safety be designed, fabricated, erected, and tested to quality standards commensurate with the importance of the safety function to be performed. Fluid systems and pressure-retaining components are part of the RCPB and other fluid systems that are important to safety. Such systems (1) prevent or mitigate the consequences of accidents and malfunctions originating in the RCPB, (2) permit shutdown of the reactor and maintain it in a safe shutdown condition, and (3) retain radioactive material.

NRC RG 1.26 (Reference 11) is the principal document that is used to identify, on a functional basis, the components of systems that are important to safety and that are in Quality Groups A, B, C, and D, which are defined below. ASME Section III, or safety Class 1, components that are part of the RCPB are identified in 10 CFR 50.55a (Reference 12).

Systems and components are assigned to quality groups in accordance with the quality group classification system (NRC Quality Groups A, B, C or D) defined in NRC RG 1.26 (Reference 11), which was established for water-steam-containing components important to safety. Two other quality groups, E and G, are defined, in addition to those designated in NRC RG 1.26, to indicate the governing design codes for the components that are not covered under NRC Quality Groups A, B, C, or D.

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RAI No.: 29-7926





RG 1.29 Regulatory Position C.2 provides guidance regarding what the applicant has referred to as “seismic Category II.” Please clarify the definition of seismic Category II on DCD Tier 2, Section 3.2.1, page 3.2-4 to address the following issues regarding consistency with this portion of RG 1.29:

1. The second paragraph of item (b), “Seismic Category II,” refers to proximity to safety-related equipment and prevention of a “component or structure … fulfilling its required function.” This statement is inconsistent with Position C.2, which refers to the functioning of any seismic Category I feature, and should be clarified for consistency with the cited guidance.

2. This second paragraph also does not include the set of SSCs whose failure “could result in incapacitating injury to occupants of the control room,” as stated in Position C.2, so this should be included for consistency with the cited guidance.

3. For clarity, terms such as “component or structure” and “equipment or structures” should be replaced by the more general “SSCs.”

4. Finally, the statement in the third paragraph of item (b) that “NNS [non-nuclear safety] SSCs are designed to preclude a gross structural failure…” is consistent with Regulatory Position C.2 and addresses aspects of items (a) and (b) above, but NNS is later defined to be anything not ASME Class 1, 2, or 3. In addressing items (a) and (b) above, this paragraph should also be revised to clarify its intent—as currently written, the DCD commits to design all NNS SSCs using these criteria, which is not necessary for conformance with RG 1.29.

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Response

1,2. The first and second paragraphs of item b. of DCD Tier 2 subsection 3.2.1 will be changed to reflect that seismic Category II SSCs are those which do not perform a safety related function, and whose continued function is not required, but whose structural failure could reduce the functioning of a seismic Category I SSC to an unacceptable safety level or could result in incapacitating injury to occupants of the control room. This change is made to be consistent with regulatory position C.2 of Regulatory Guide 1.29.

3. The terms of “component or structure” and “equipment or structures” will be replaced by the general term of “SSCs.”

4. “NNS SSCs” in the third paragraph of item b. of DCD Tier2, subsection 3.2.1 will be changed to “Seismic Category II SSCs” since the paragraph is not intended to apply to all non-safety related SSCs.

Impact on DCD

DCD Tier 2, item b. of subsection 3.2.1 will be revised as indicated in the attached markup.

Impact on PRA






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APR1400 DCD TIER 2

3.2-4

form an interface between seismic Category I and seismic Category II/III (or NS) features are designed to seismic Category I requirements in accordance with Regulatory Position C.3 of NRC RG 1.29 (Reference 5). Seismic Category I design requirements extend to the first seismic anchor (restraint) beyond the defined boundaries.

Portions of some non-safety-related systems (e.g., fire protection system) are classified as seismic Category I to conform with NRC RG 1.189.

Seismic Category I SSCs are designed to remain functional and within the applicable stress and deformation limits (elastic range of material properties) when subjected to the effects of the vibratory motion of the operating basis earthquake (OBE) in combination with normal operation loads. This design is based on the design for SSE loads where an OBE is defined as one third of the SSE, as described in Subsection 3.7.1.1. Seismic Category I structures are protected from interaction with adjacent non-seismic structures, as described in Subsection 3.7.2.8. The seismic classifications of platforms and miscellaneous steel located in seismic Category I application are described in Subsection 3.8.3.

Seismic Category I SSCs meet the QA requirements of 10 CFR Part 50, Appendix B (Reference 10). The criteria used for the design of seismic Category I SSCs are described in Section 3.7.

b. Seismic Category II

SSCs that do not perform a nuclear safety-related function and whose continued function is not required are classified as non-nuclear safety (NNS) (see Subsection 3.2.3).

NNS SSCs that are not seismic Category I but whose failure by virtue of physical proximity to safety-related equipment or structures could prevent a component or structure from fulfilling its required function are classified as seismic Category II.

NNS SSCs are designed to preclude a gross structural failure resulting from an SSE that could degrade the ability of an adjacent safety-related SSC to function to

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Seismic Category II applies to SSCs which do not perform safety-related function, and whose continued function is not required, but whose structural failure could reduce the functioning of a seismic Category I SSC to an unacceptable safety level or could result in incapacitating injury to occupants of the control room.

Seismic Category II


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RAI No.: 29-7926





In DCD Tier 2, Table 3.2-1, Remark (3)(d) is intended to designate seismic Category II SSCs. Table 3.2-1 contains several instances where this remark has been applied to SSCs that are not designated seismic Category II and other instances where this remark has not been applied to seismic Category II SSCs. Please clarify if the seismic classification or the remark is in error for each of the cases discussed above. A list of examples are provided below, but this list is not exhaustive:

1. Non-safety UPS in AB, CPB has a portion classified seismic Category II, but does not have this remark. Also see page 3.2-64 for additional examples.

2. Non-safety soft control (IFPD) (seismic Category III) and “Piping and valves on the SIS filling line from and including SI-700, 714, 701, 715 to the piping downstream of SI-476, 435, 478, 447” (seismic Category I).

Response

Remark (3)(d) for seismic Category II SSCs has been reviewed in DCD Tier 2, Table 3.2-1 and for those instances that did not include the remark (3)(d), it will be added appropriately. RAI 72-8020 was also received that pertains to issues identified in Table 3.2-1. Therefore, to address all issues associated with Table 3.2-1 in a single consolidated mark-up, updates to address the items identified in this RAI will be included in the response to Question 03.02.02-5 of RAI 72-8020 (ref. KHNP letter MKD/KW-15-0171L dated September 25, 2015).

Impact on DCD

DCD Tier 2, Table 3.2-1(Pages 3.2-19, 3.2-24, 3.2-34, 3.2-46, 3.2-51, 3.2-52, 3.2-53, 3.2-62, 3.2-64, 3.2-65, 3.2-68, 3.2-71, 3.2-74, 3.2-75~77, 3.2-82, 3.2-91, 3.2-92 and 3.2-109) will be revised as indicated in the Attachment to Question 03.02.02-5 of RAI 72-8020.

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Korea Electric Power Corporation / Korea Hydro & Nuclear Power Co., LTD

Docket No. 52-046

RAI No.: 29-7926

SRP Section: 03.02.01 - Seismic Classification




Regulatory Guide 1.29 is indicated as guidance for meeting SRP 3.2.1. Regulatory Guide 1.29, Regulatory Position C.1 states that “cooling water and seal water systems or portions thereof that are required for functioning of reactor coolant system components important to safety, such as reactor coolant pumps [RCPs]” should be seismic Category I. DCD Tier 2, Table 3.2-1 lists the RCPs as seismic Category I, consistent with this position; however, in note N-3 to Table 3.2-1, the DCD indicates an exception to RG 1.29:

Loss of cooling water and/or seal water service to the reactor coolant pumps (RCPs) may require stopping the pumps. However, the continuous operation of the pumps is not required during or following an SSE. The auxiliaries are therefore not necessarily seismic Category I. The provision for cooling water to the pump bearing oil cooler and pump motor air cooler does not conform with the requirements of NRC RG 1.29.

In addition, note N-4 states: “Only those structural portions of the RCPs that are necessary to provide reasonable assurance of the integrity of the RCPB are Safety Class 1.”

These notes should be revised to clarify which portions of the pump and its support systems (auxiliaries) are seismic Category I, Safety Class 1, Quality Group A, and subject to 10 CFR Part 50, Appendix B quality assurance requirements, as listed for the RCPs in Table 3.2-1. A complete justification from exceptions to RG 1.29 and 1.26 is also necessary, with reference to the key functions of the pump (e.g., seal cooling, coastdown flow, and reactor coolant pressure boundary (RCPB) integrity, as described in DCD Section 5.4.1). General statements such as “not necessarily” and “those structural portions … that are necessary” are not sufficient to support the staff’s finding in accordance with SRP Sections 3.2.1 and 3.2.2.

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Response SUMMARY:

Based on the following information, the APR1400 RCP auxiliaries do not need to be categorized as seismic Category I:

1. The identical functions of the APR1400 and SYS80 RCPs can be divided into a safety function (i.e., maintaining the RCPB) and a non-safety function (i.e., providing forced reactor coolant system flow during specified modes of operation).

2. There are only minor differences between the APR1400 and SYS80 RCP designs. These differences do not impact the seismic categorization of RCP auxiliaries.

3. Based on a response to a similar RAI for the SYS80 Standard Safety Analysis Report (CESSAR), the NRC agreed that the SYS80 RCP auxiliaries only supported the non-safety function and. therefore, need not be categorized as Seismic Category I.

4. None of the changes in NRC licensing requirements (e.g., SRP 3.2.1 and 3.2.2, RGs 1.29 and 1.26, etc.) since 1975 should adversely impact the conclusion that the APR1400 RCP auxiliaries do not need to be categorized as seismic Category I.

Therefore, revisions to the APR1400 DCD as a result of this RAI will specifically clarify which portions of the RCP and its support systems (auxiliaries) are, or are not, Seismic Category I, including the non-seismic categorization of the RCP Auxiliary Systems. The following sections provide the background information and rationale that support each of the aforementioned items.

1. FUNCTIONS OF THE APR1400 AND SYS80 RCPs

The APR1400 document “Design Specification for the Reactor Coolant Pump” (Reference 1) and SYS80 document “Specification for Standard Plant for Reactor Coolant Pumps” (Reference 2) clearly separate the components and auxiliaries of the RCPs into 1) safety related components subject to meeting Seismic Category I (i.e., those components that comprise part of the RCPB) requirements, and 2) those remaining components/auxiliaries that are not required to be designed to Seismic Category 1.

Subsection 6.4.1.1 of Reference 1 (see Attachment 1) provides the list of Section III Code Class RCP components and seal water piping that are designed to seismic Category I for APR1400. Subsection 4.1.1 of Reference 2 (see Attachment 2) provides the list of Section III Code Class RCP components and seal water piping that are designed to seismic Category I for SYS80.

Direct inspection of these attachments indicates that the same APR1400 and SYS80 RCP components are required to be designed to seismic Category I.

2. MINOR DIFFERENCES BETWEEN THE APR1400 AND SYS80 RCP DESIGNS

The APR1400 RCP design can be directly traced back to the SYS80 RCP design. While the 156 page APR1400 specification (Ref. 1) and 98 page SYS80 specifications are different in

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detail, there are only minor differences in the design. Table 1 provides a truncated comparison of major RCP design parameters.

Table 1. Reactor Coolant Pump Major Design Parameters Parameter APR1400 SYS80 Nominal flow rate (GPM) 121,600 111,400 Rated head (ft) 360 365 Design Pressure (psia) 2500 2500 Design Temperature (oF) 650 650 Design life (yr) 60 40

As indicated in Item 1, Attachments 1 and 2 identify that the same RCP components make up the RCPB associated with the safety function of the RCPs.

In addition, both APR1400 Section 6.5.1.1 and SYS80 Section 4.1.5.1 state:

“The pump assembly shall be designed to withstand, without damage, coast down following loss of electric power, in conjunction with Safe Shutdown Earthquake (SSE) loads specified in Appendix III. SSE accelerations specified in Appendix III shall be used for design of components and appurtenances for which loads are not specifically given in Appendix III.”

Even though the APR1400 specification is about 50% larger than the SYS80 specification, the additional information mainly provides clarifications and additional detail not included in the SYS80 specification. An important example is APR1400 Section 6.3.12.1, which states:

“The pump assembly shall be designed to withstand loss of cooling water to the bearing oil coolers for a minimum of 30 minutes without damage which could affect pump coastdown.”

While the SYS80 specification does not include this statement, CENPD-201-A and SUPP. 1 (References 3 and 4) submitted to the NRC as part of the response to a similar SYS80 DCD RAI, provided the justification that the SYS80 RCPs meet the same 30 minute requirement identified in Section 6.3.12.1 of the RCP Design Specifications for APR1400.

The RCP auxiliary systems of interest (e.g., pump bearing oil cooler, seal injection, pump motor air cooler, etc.) only support the non-safety function and are not required to support the safety function. For SYS80, the RCP auxiliaries were accepted by the NRC as not being required to be categorized as seismic Category I. One minor change in the APR1400 RCP auxiliaries is the removal of the RCP throttle coolers from the RCP seal coolant system. CENPD-201 SUPP. 1 points out that the seals are primarily cooled by seal injection and the limiting component for potential impact on RCP coastdown is the thrust bearing. Because of the similarity in design and operation of the APR1400 and SYS80 RCPs, the thrust bearing

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design and thrust loads are essentially identical for APR1400 and SYS80; therefore, the CENPD-201 SUPP. 1 tests justifying 30 minutes of RCP operation with loss of component cooling water to the thrust bearings are also applicable to the APR1400 RCPs.

3. NUREG-0852 APPROVAL THAT SYS80 RCP AUXILIARY SYSTEMS ARE NOT REQUIRED TO MEET SEISMIC CATEGORY I

Attachment 3 is the excerpt from NUREG-0852 (Reference 5) that provides the NRC approval of the response to a similar RAI for SYS80. The RAI response reviewed by the NRC included References 3 and 4, which justified the exception to RG1.29 regarding non-seismic classification of the component cooling water supply and seal injection water supply to the SYS80 RCPs. Instead of including References 3 and 4 to support the exception to RG1.29, Section 6.3 of the APR1400 RCP specification (Reference 1) requires the same operational capability justified by References 3 and 4 (e.g., see Section 6.3.12.1 of Reference 1).

This issue of the seismic classification of the RCP auxiliaries was not addressed in the NRC SER for System 80+ DCD Sections 3.2.1 or 9.2.2 (see Reference 6). A potentially related item concerning RCS leakage due to failure of the RCP seals was addressed because failure of the RCP seals could result in an interfacing small break LOCA, if the leakage resulting from the failure was significant. In response to this concern, Westinghouse submitted WCAP-16175-P-A (Reference 7). Based on an assessment of the improved seal design implemented in SYS80 and SYS80+, Westinghouse concluded:

“Results of this assessment indicate that the conditional probability of a RCP seal LOCA is negligible for short duration loss of cooling events, those less than 4 hours. It was also noted that the RCP seal failure probability is negligible for CE PWRs with the improved RCP seal designs.”

The NRC conclusion in their approval of the topical states:

“The NRC staff finds that the RCP seal leakage model as documented in the WCAP-16175-P, Revision 0, is acceptable for use in plant-specific PSAs and can be used in support of risk-informed applications for CE plants, provided it is used within the conditions, limitations, and modifications listed in Section 4.0 of this SE.”

4. IMPACT OF CHANGES IN NRC LICENSING REQUIREMENTS SINCE APPROVAL OF NON-SEISMIC CATEGORIZATION OF SYS80 RCP AUXILIARIES

Of the NRC licensing documents identified in this RAI (i.e., SRP Sections 3.2.1/3.2.2 and RG 1.26/1.29), only SRP 3.2.1 and RG 1.29 may potentially impact the seismic categorization of the RCP auxiliaries.

Between the USNRC approval of the System 80 DCD (CESSAR) and the initiation of the APR1400 review, SRP 3.2.1 was revised from Revision 1 to Revision 2. While Revision 2 of SRP 3.2.1 is a complete rewrite of the SRP, including the addition of a section addressing the SRP Acceptance Criteria (i.e., a clarification of the more general regulatory requirements), these clarifications and additions still do not go beyond invoking the GDCs and RGs (e.g., RG 1.29). Therefore, by itself, the changes in SRP 3.2.1 Revision 2, do not directly impact regulatory requirements for the RCP auxiliaries.

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Between the USNRC approval of the System 80 DCD (CESSAR) and the initiation of the APR1400 DCD review, RG 1.29 was revised from Revision 3 to Revision 4. Major additions to Revision 4 included 1) adding fire protection information, 2) updating source term calculations and 3) addressing potential backfit analyses. None of these changes have any impact on RCP system auxiliaries.

Although appearing editorial, a potentially significant impact was made by changing all “… requires that nuclear power plant structures, systems, and components (SSCs) important to safety should be designed to withstand the effects of earthquakes….” to ““… requires that nuclear power plant structures, systems, and components (SSCs) important to safety must be designed to withstand the effects of earthquakes….” (emphasis added). This change could enhance the seismic requirements for implementing the design of systems important to safety. However, the quotation from RG1.29 in the first paragraph of this RAI (see above) stops before must and reverts to should. In any case, the point of this response is that the RCP auxiliaries of concern should not be considered seismic Category I.

Therefore, none of the changes in NRC licensing requirements since 1975 should adversely impact the conclusion that the APR1400 RCP auxiliaries do not need to be categorized as seismic Category I.

5. REVISIONS TO THE APR1400 DCD REQUESTED BY THIS RAI

Revisions to the APR1400 DCD as a result of this RAI are provided as DCD page mark-ups in Attachment 4. In Table 3.2-1, Line 79 d. is revised to indicate only Reactor Coolant Pressure Boundary components of the RCPs are seismic Category I. Notes (N-3) and (N-4) are revised to clarify justification for the non-seismic classification of the RCP auxiliaries and to more clearly state the justification of the non-seismic classification of the RCP auxiliaries, beyond those SSCs that are part of the RCPB.

6. REFERENCES

1. 11A60-FS-DS480 Rev. 03, “APR1400 DC, Design Specification for Reactor Coolant Pump,” KEPCO E&C NSSS Division, 03/2015 (Proprietary)

2. SYS80-PE-480 Rev. 02, “Specification for Standard Plant for Reactor Coolant Pumps,” Combustion Engineering Nuclear Power Systems, 03/1978 (Proprietary)

3. CENPD-201-A, “Performance of C-E System 80 Reactor Coolant Pump with Loss of Component Cooling Water,” Combustion Engineering Nuclear Power Systems, 03/1978 (Proprietary)

4. CENPD-201-A, Supp. 1, “System 80 Reactor Coolant Pump Loss of Component Cooling Water Test Report,” Combustion Engineering Nuclear Power Systems, (undated) (Proprietary)

5. NUREG-0852, “Safety Evaluation Report related to the final design of the Standard Nuclear Steam Supply Reference System CESSAR System 80,” USNRC, 11/1981

03.02.01-5 - 6 / 6 KEPCO/KHNP

Non-Proprietary

6. NUREG-1662, “Final Safety Evaluation Report Related to the Certification of the System80 + Design,” USNRC, 08/1994 WCAP-16175-P-A, “Model for Failure of RCP Seals GivenLoss of Seal Cooling in CE NSSS Plants,” Westinghouse Electric Co., 03/2007(Proprietary)

7 WCAP-16175-P-A, “Model for Failure of RCP Seals Given Loss of Seal Cooling in CE NSSS Plants,” Westinghouse Electric Co., 03/2007 (Proprietary)

Impact on DCD

DCD Table 3.2-1 will be revised as indicated in Attachment 4.

Impact on PRA

There is no impact on PRA.


There is no impact on Technical Specifications.


There is no impact on Technical, Topical or Environmental Reports.

Non-Proprietary RAI 29-7926 - Question 03.02.01-5 Attachment 1 (1/1)

TS


TS


38155

스티커 노트

38155에 의해 설정된 None

38155

스티커 노트

38155에 의해 설정된 Accepted

Non-Proprietary

APR1400 DCD TIER 2

3.2-69

Table 3.2-1 (54 of 86)

Item No. / Principal SSCs Location(2) Safety Class

Quality Group Codes and Standards

10 CFR 50, App. B(3)

Seismic Category Remarks

79. RC – Reactor Coolant

a. Reactor vessel RCB SC-1 A ASME Sec. III NB-2007 with 2008 addenda

Yes I

b. SG (primary/secondary) RCB SC-1/ SC-2

A/B ASME Sec. III NB-2007 with 2008 addenda ASME Sec. III NC-2007 with 2008 addenda

Yes I (N-1)

c. PZR RCB SC-1 A ASME Sec. III NB-2007 with 2008 addenda

Yes I

d. RCP RCB SC-1 A ASME Sec. III NB-2007 with 2008 addenda

Yes I (N-3, 4)

e. POSRV (N-8)

1) Main valves RCB SC-1 A ASME Sec. III NB-2007 with 2008 addenda

Yes I

2) Spring-loaded pilot valves RCB SC-1 A ASME Sec. III NB-2007 with 2008 addenda

Yes I

3) Double motor-operated pilot valves RCB SC-1 A ASME Sec. III NB-2007 with 2008 addenda

Yes I

4) Motor-operated isolation valves RCB SC-1 A ASME Sec. III NB-2007 with 2008 addenda

Yes I

5) Manual isolation valves RCB SC-1 A ASME Sec. III NB-2007 with 2008 addenda

Yes I

f. Sparger RCB SC-3 C ASME Sec. III ND Yes I

Rev. 0

RAI 29-7926 - Question 03.02.01-5 Attachment 4 (1/2)

38155

설명선

(RCPB Components)

Non-Proprietary

APR1400 DCD TIER 2

3.2-101

Table 3.2-1 (86 of 86)

NSSS Notes: (N-1) Two safety classes are used for heat exchangers to distinguish primary and secondary sides where they are different. (N-2) Only those core support structures necessary to support and restrain the core and to maintain safe shutdown capability are classified as seismic

Category I. (N-3) Loss of cooling water and/or seal water service to the reactor coolant pumps (RCPs) may require stopping the pumps. However, the continuous

operation of the pumps is not required during or following an SSE. The auxiliaries are therefore not necessarily seismic Category I. The provision for cooling water to the pump bearing oil cooler and pump motor air cooler does not conform with the requirements of NRC RG 1.29.

(N-4) Only those structural portions of the RCPs that are necessary to provide reasonable assurance of the integrity of the RCPB are Safety Class 1. (N-5) Safety classes of piping within the RCPB (as defined in 10 CFR 50) are selected in accordance with the ANSI/ANS 51.1 criteria. Safety Classes 1,

2, 3 and Non-Nuclear Safety of ANSI/ANS 51.1 are equivalent to Quality Groups A, B, C, and D of NRC RG 1.26, respectively. (N-6) Flow-restricting orifices are provided in the nozzles for the RCS sampling lines, the pressurizer (PZR) level and pressure instruments, the RCP

differential pressure instrument lines, the common SI header pressure instrument lines, the RCP seal pressure instrument lines, the charging line differential pressure instrument line, and the SI hot leg injection pressure instrument lines to limit flow in the event of a downstream break of a nozzle. The orifice size, 5.55 mm (7/32 in) diameter × 25.4 mm (1 in) long, precludes exceeding fuel design limits while using minimum makeup rates. This permits orderly shutdown in the event of a downstream break in accordance with 10 CFR 50, Appendix A, GDC 33. A reduction may therefore be made in the classification of downstream lines of the orifice.

(N-7) All containment isolation valves (and their operators) within NSSS scope of supply including manual valves, check valves, and relief valves, which also serve as isolation valves, are subject to the pertinent requirements of the Quality Assurance Program.

(N-8) The POSRVs are used for overpressure protection and rapid depressurization function. (N-9) The “Associated Circuits” are defined, in accordance with IEEE Standard 384, as equipment, components, or systems the functions of which are

Non-Nuclear Safety (NNS) and electrically Non-Class 1E, though their failures or abnormal states can affect the Class 1E equipment, components, or systems due to the effects of less than the minimum separation or the absence of electrical isolation from the Class 1E equipment, components, or systems. Consequently, the equipment, components, or systems, which are defined as “Associated Circuits” although they are functionally Non-Nuclear Safety, are subject to the qualification requirements placed on Class 1E equipment, components, or systems.

Rev. 0

RAI 29-7926 - Question 03.02.01-5 Attachment 4 (2/2)

38155

줄 긋기

38155

설명선

The reactor coolant pump (RCP) auxiliaries are not required to be classified as seismic Category I because 1) continuous operation of the pumps is not required during or following an SSE and 2) sufficient time is available (i.e., >30 minutes) for the operator to stop the RCPs before loss of the RCP auxiliaries would cause any damage to the RCPs (see CENPD-201-A).

38155

줄 긋기

38155

줄 긋기

38155

설명선

comprise the RCPB and, therefore, support the safety function

38155

설명선

must be categorized as

Non-Proprietary

03.02.01-6 - 1 / 2 KEPCO/KHNP




RAI No.: 29-7926





In DCD Tier 2, Table 3.2-1, the letdown heat exchanger supply and return piping between the valves CC-297, CC-301, CC-1685, and CC-1686 in division I, which appears to be part of the component cooling water system (CCW), is identified as seismic Category II, Quality Group D. This is supported in Figure 9.2.2-1 (Page 9.2-149). The letdown heat exchanger itself (part of the chemical and volume control system (CVCS)) is classified as seismic Category I, Quality Group C. This transition is not illustrated in the system figure. Please justify why a portion of CCW, a safety-related system, is not seismic Category I, and why its classification is not consistent with the heat exchanger that it supports. Updates to DCD Tier 2, Table 3.2-1 and associated system figures may be needed to clarify these classifications.

Response

The CVCS including the letdown heat exchanger is not required to perform any accident mitigation or safe shutdown function and the letdown line in the CVCS is automatically isolated by the engineered safety features actuation signal (ESFAS) following a LOCA. The cooling function for the letdown heat exchanger is not also required. Therefore the letdown heat exchanger supply and return piping between the valves CC-297, CC-301, CC-1685, and CC-1686 in the CCWS is classified as seismic Category II, Quality Group D in accordance with classification criteria of USNRC RG 1.26 and RG 1.29.

Impact on DCD

There is no impact on the DCD.

Impact on PRA


Non-Proprietary

03.02.01-6 - 2 / 2 KEPCO/KHNP





response to request for additional information · nrc rg 1.189 (reference 8) is used as guidance...

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