KAERI

관한설계요건에

E그-r-‘-

원자력발전소

-줄

저l

개량형중수로

제출합니다.

귀하한국원자력연구소장

본 보고서를

기술보고서로

(요약)

PLANT

기술관리분야

설계요건서개량형

(FUTURE CANDU

REQUIREMENT DOCUMENT

Summary)

POWER

울진5，6호기

원자력발전소

NUCLEAR

1996년 3월

제출부서명:

로수l중

DESIGN

Executive

제목

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c>작

현o..장

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S.A. Usmani (AECL, Toronto)

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(개 량중수로개 발분야책 임 자)

2J-¢ 이 .9.1-,- TI τ코

(연구위원)c::>-.一

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개량형 중수로 발전소 설계요건서(요약)는한국을 위시하여 차세대 중수로

형 발전소에 대한 사용자 요건을 분명하고 완벽하게 기술하고있다. 기술된 요건

들은 가합중수로의 경험에 입각한 실증된 기술을 기초로 하여 범세계적인 현행

요건서에 명시된 설계요건들과 부합시키고자 한다. 나아가서， 이 종합된 설계요건

서는 현재 채택가능한 범위 내에서 사용자의 입력을 최대한 포함시키고， 성능과

안전성을 증진시키기 위하여 단순하고 강력하며 보다 여유 있는 설계를 보증하

고 있다.

예상되는 본 개량형 중수로 설계요건서의 용도는 다음과 같다.

- 사용자 측의 요건수립을 촉진하기 위하여 한전과 같이 중수로형 발전소에

관심이 있는 사용자와의 심도 있는 토론의 기초를 제공

- 인허가 쟁점 제시를 포함하여 높은 인허가성을 제고하므로써 한국을 위시

하여 미래 중수로형 발전소에 대한 규제의 근거를 설정하며，

- 최종상세설계， 인허가， 그리고 건설을 위한 입찰제의서에 사용될 기술요건을

제공하고， 개량형 중수로의 완성과 운전을 위한 초기투자에 따른 위험부담

이 극미하다는 강한 투자확신의 근거를 제공한다.

본 설계 요건서는 핵증기공급계통과 보조설비계통은 물론 변전소와 송전

선을 연결하는 회로차단기의 배전반 측에 있는 급전망과의 연계부분까지 망라한

발전소 전체를 대상으로 하고 있다. 또한 본 요건서는 발전소내의 저준위 방사성

폐기물의 처리요건과 사용후핵연료 저장요건을 포함하고 있으며 소외 폐기물 폐

기는 본 요건서에서 취급하지 않았다.

요건서 요약집에서는 정책일람과 최상위 설계요건을 요약하였다. 정책일람

은 설계， 개발 및 계획수행을 위한 핵심사항에 대한 사용자 측의 입장을 제시하

였으며， 최상위 설계요건은 한국의 개량형 중수로 발전소의 목표를 달성시키기

위한 핵심요소이며 1990년대 및 그 이후에도 경쟁력 있는 원자력 발전소임을 확

인사켜 준다.

ABSTRACT

The Future CANDU Requirements Document (FCRED) describes a

clear and complete statement of utility requirements for the next generation of

CANDU nuclear power plants including those in Korea. The requirements are

based on proven technology of PHWR experience and are intended to be

consistent with those specified in the current international requirement

documents. Furthermore, these integrated set of design requirements,

incorporate utility input to the extent currently available and assure a simple,

robust and more forgiving design that enhances the performance and safety.

The anticipated uses of the FCRED are as follows;

• Provide a basis for further discussion with the interested CANDU client such as KEPCO to facilitate establishment of client-specific requirements.

• Establish a regulatory basis for Future CANDUs including those in Korea

which includes addressing of licensing issues and which provides high

assurance of licensability.

• Provide technical requirements for use in a bid package for eventual detailed

design, licensing and construction, and which provide a basis for strong

investor confidence that the risks associated with initial investment to

complete and operate the future CANDU plant remain minimal.

The FCRED addresses the entire plant, including the nuclear steam

supply system and the balance of the plant, up to the interface with the

utility grid at the distribution side of the circuit breakers which connect the

switchyard to the transmission lines.

Requirements for processing of low level radioactive waste at the plant

site and spent fuel storage requirements are included in the FCRED. Off-site

waste disposal is beyond the scope of the FCRED.

The executive summary document summarizes policy statements and

top-tier design requirements. The policy statements provide utility positions on

key aspects of design, development, and program implementation. The top-tier

design requirements are the key elements in meeting the objectives of Future

CANDU units in Korea and to ensure a viable nuclear power generation

option for the 1990' s and beyond.

TABLE OF CONTENTS

SECTION PAGE

1. INTRODUCTION 2

1.1 Objective and Scope of the Future CANDU Requirement Document 2

1.1.1 Objective 2

1.1.2 Scope of the FCRED 2

1.2 Structure of the FCRED 2

1.2.1 Structure 2

1.2.2 Requirements/Rationale 3

2. POLICY STATEMENTS 4

2.1 Simplification 4

2.2 Design Margin 5

2.3 Human Factors 5 2.4 Safety Design 6 2.5 Design Basis Versus Safety Margin 7

2.6 Regulatory Stabilization 7

2.7 Plant Standardization 7 2.8 Proven Technology 8

2.9 Maintainability 8

2.10 Constructibility 8 2.11 Quality Assurance 9

2.12 Sabotage Protection 9 2.13 Good Neighbour 9

2.14 Economic Policy 10

3. TOP TIER DESIGN REQUIREMENTS 12

3.1 Top-Tier Safety Design Requirements 12

3.1.1 Accident Resistance 12

3.1.2 Core Damage Prevention 13

3.1.3 Mitigation 14

3.1.4 Supplementary Requirements 14

3.2 Top-Tier Performance Design Requirements 15

3.2.1 Plant Characteristics Requirements 15

3.2.2 Maneuvering and Transient Response Requirements 15

3.2.3 Reliability and Availability Requirements 16

3.2.4 Operability, Maintainability and Testing Requirements 16

3.2.5 Instrumentation and Control System Requirements 17

TABLE OF CONTENTS

SECTION PAGE

3.3 Top-Tier Constructibility Requirements 18

3.3.1 Construction Duration and Design Completion Requirements 18

3.3.2 Construction and Design Coordination Requirements 18

3.3.3 Advanced Construction Technology Requirements 19

3.3.4 Integrated Construction Planning and Scheduling Requirements 19

3.4 Top-Tier Design Process Requirements 19

3.4.1 Design Integration Requirements 20

3.4.2 Information Management System (IMS) Requirements 20

3.4.3 Engineering Verification of As-Built Conditions Requirements 20

4. SUMMARY OF TOP-TIER DESIGN REQUIREMENTS 22

TABLES

Table 2.1 Future CANDU Safety Foundation 11

Table 4.1 Summary of Top-Tier Requirements 23

ILLUSTRATIONS

Figure 1 FCRED Organization 3

LIST OF ABBREVIATIONS

FCRED

NPP

QA

HMIS

LOCA

LOECC

PRA

LDB

SMB

ROP

DBE

IMS

Future CANDU Requirements Document

Nuclear Power Plant

Quality Assurance

Human-Machine Interface System

Loss of Coolant Accident

Loss of Emergency Core Cooling

Probabilistic Risk Assessment

Licensing Design Basis

Safety Margin Basis

Regional Over Power

Design Basis Earthquake

Information Management System

1. INTRODUCTION

1.1 OBJECTIVE AND SCOPE OF THE FUTURE CANDU REQUIREMENT

DOCUMENT

1.1.1 Objective

The objective of the Future CANDU Requirements Document (FCRED) is to present

a clear and complete statement of utility requirements for the next generation of CANDU

nuclear power plants including those in Korea. The requirements are based on proven

technology of PHWR experience and are intended to be consistent with those specified in the

current international requirement documents. Furthermore, these integrated set of design

requirements, incorporate utility input to the extent currently available and assure a simple,

robust and more forgiving design that enhances the performance and safety.

The anticipated uses of the FCRED are as follows;

• Provide a basis for further discussion with the interested CANDU client such as KEPCO to facilitate establishment of client-specific requirements.

• Establish a regulatory basis for Future CANDUs including those in Korea which includes addressing of licensing issues and which provides high assurance of licensability.

• Provide technical requirements for use in a bid package for eventual detailed design, licensing and construction, and which provide a basis for strong investor confidence that the risks associated with initial investment to complete and operate the future CANDU plant remain minimal.

1.1.2 Scope of the FCRED

The FCRED addresses the entire plant, including the nuclear steam supply system

and the balance of the plant, up to the interface with the utility grid at the distribution side

of the circuit breakers which connect the switchyard to the transmission lines.

Requirements for processing of low level radioactive waste at the plant site and

spent fuel storage requirements are included in the FCRED. Off-site waste disposal is beyond

the scope of the FCRED.

1.2 STRUCTURE OF THE FCRED

1.2.1 Structure

The structure of the FCRED is patterned after the format of the Korean Standard

NPP Design Requirement document K-SRED. The FCRED is divided into two volumes, an

executive summary of top-tier requirements and a complete set of overall design

requirements. An illustration of the structure of these two documents is provided in Figure 1.

The executive summary document summarizes policy statements and top-tier design

requirements. The policy statements provide utility positions on key aspects of design,

development, and program implementation. The top-tier design requirements are the key

- 2 -

elements in meeting the objectives of Future CANDU units in Korea and to ensure a viable

nuclear power generation option for the 1990's and beyond.

The overall design requirements contain common requirements which have application

to a number of plant systems.

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Safety

Introduction and

Policy Statements

Perfor­

mance

Construct-ibility

Design

Process

Common Requirements

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Figure 1: FCRED Organization

The specific technical requirements on systems are covered in various system

requirement documents, which are complementary to the executive summary and the overall

design requirement documents

1.2.2 Requirements/Rationale

The summary of top-tier requirements includes a narrative text, which typically

states policy or necessary background. The narrative text should be carefully reviewed to

assure understanding of policy and the background.

The overall design requirements specified in the FCRED are organized in a format

which provides the rationale for each requirement. The rationale provides the basis for the

requirement and a clear understanding of the requirement and its intent to the users.

- 3 -

2. POLICY STATEMENTS

The policy statements are not design requirements by themselves, but are generalized

targets for a set of requirements. The policy statements included in this section are as

follows:

Simplification

Design Margin

Human Factors

Safety

Design Basis Versus Safety Margin

Regulatory Stabilization

Plant Standardization

Use of Proven Technology

Maintainability

Constructibility

Quality Assurance

Sabotage Protection

Good Neighbour

Economic Policy

2.1 SIMPLIFICATION

It is policy to emphasize simplicity in all aspects of plant design, construction, and

operation. Because of the fundamental importance of simplicity, future CANDU designs will

pursue simplification opportunities with high priority and will assign greater importance to

simplification in design decisions than has traditionally been done.

From the viewpoint of plant operation, plant simplification requirements include:

• Use of a minimum number and diversity of systems, valves, pumps, instruments, and other

mechanical and electrical equipment, consistent with the essential safety and functional

requirements;

• Provision of instrumentation and control which will simplify plant operation and reflect the

operator's needs and capabilities;

• Provision of system and component designs which minimize demands on the operator

during normal operation as well as transient and emergency conditions (e.g., minimizing

system realignments to accomplish safety functions, total segregation of safety and

non-safety functions unless justified);

• Provision of equipment design and layout which facilitate maintenance;

• Provision of simple protective logic and actuation systems;

• Use of standardized components to facilitate operations and maintenance;

• Provision of design and layout for ease of construction;

• Use of an integrated 3-dimensional CADDS plant model and advanced information and

communication system technology to facilitate achievement of above requirements.

Plant simplification will be specified as an integral part of the design process in

order to maximize overall simplicity in the face of sometimes competing objectives.

4 -

2.2 DESIGN MARGIN

It is policy that significant margins be designed into future CANDU units so as to

make it a more forgiving and rugged plant. Significant design margins are of fundamental

importance to nuclear plant safety and economics. Significant design margins wiL' provide

benefit in the following ways:

• Provide designed-in capability to accommodate transients without causing initiation of

special safety systems!

• Provide the operator time to assess and deal with upset conditions with minimum potential

for damage;

• Provide margins to enhance system and component reliability and to minimize the potential

of exceeding limits (e.g., technical specifications) which might require derating or shutdown;

- Provide additional assurances that the plant life requirement of 60 years can be met.

The design margins policy implementation is expected to result in a design which

goes beyond regulatory requirements in various respects. It is policy that these margins be

maintained and be available to the plant operator and not be eroded by regulatory

requirements since this would result in unnecessarily stringent operating envelopes.

2.3 HUMAN FACTORS

This policy is to systematically include human factors considerations in the design of systems, facilities, equipment and procedures. All aspects of plant design for which there is an interface with plant personnel shall incorporate human factors considerations. Human factors driven design considerations shall be applied consistently plant-wide. This includes those aspects of the design which affect:

• Monitoring, control, and protection functions assigned to plant operators;

• Monitoring and diagnostic functions performed by plant engineers and managers during

normal, upset, and emergency conditions;

• Inspection, on-line and off-line surveillance testing, preventative maintenance, and corrective

maintenance functions assigned to maintenance personnel.

To implement this policy, it is essential that there be participation by qualified,

experienced operators and maintenance personnel and interaction of these personnel with

designers and human factors experts early in the design process. The design process shall

include techniques, such as mock-ups and simulators, to provide an environment in which

experienced operators and maintenance personnel can contribute to the design. Also, operating

experience from existing plants shall be reviewed and considered in order to minimize human

performance problems. Instrumentation and Control Systems shall employ modern technology.

In particular, the main control room shall utilize advanced human factor engineering control

concept in which integrated electronic displays, alarms, procedures, and controls are available

to the operators.

- o -

2.4 SAFETY DESIGN

The safety design policy is that there shall be excellence in safety both to protect

the general public and to assure personnel safety and plant investment protection. The

primary emphasis is on accident prevention (which includes accident resistance and core

damage prevention); this approach is the best way to achieve plant owner investment

protection and to achieve improved overall safety. Emphasis is also placed on mitigation of

the consequence of potential accidents so that a balanced approach to safety is achieved.

This policy of excellence in safety is implemented through an integrated design

approach to safety which addresses the above mentioned three overlapping levels of

defense-in-depth, i.e., accident resistance, core damage prevention and mitigation, and which

uses a combination of a systematic plant review for accidents, analysis for their consequences

and is supplemented by a PRA.

Accident resistance will be designed in order to minimize the frequency and severity

of initiating events which could challenge safety. Policy implementation such as simplicity,

increase design margins (including increased time for operator response), and human factors

considerations will assure accident resistance.

Core damage prevention includes the systems and features which provide high confidence that if initiating events occur they will not progress to the point of core damage. The policy on core damage prevention is to provide investment protection for the Plant Owner.

Accident mitigation provision is to establish a challenging requirement on mitigation

and to provide conservative, rugged containment systems to meet this requirement and the

regulatory requirements.

- 6 -

2.5 DESIGN BASIS VERSUS SAFETY MARGIN

The Safety Policy above describes the integrated approach to safety with the three

overlapping levels of safety protection. Each of these levels of safety protection is divided

into a Licensing Design Basis and a Safety Margin Basis as depicted in Table 2.1. The

Licensing Design Basis (LDB), is the set of future CANDU safety design requirements which

are necessary to satisfy the regulatory requirements, including LDB transients and accident

events.

The required analyses will be done with the conservative, calculation methods and

assumptions and must meet mandated regulatory acceptance criteria. In the accident analysis,

the special safety systems must perform their required safety functions without credit for

active mitigation by the process systems.

The Safety Margin Basis (SMB) contains design requirements which provide margin beyond the minimum required by the Regulations, thereby providing additional safety assurance. The SMB requirements address investment protection and severe accident protection.

The increased investment protection addresses the utility desire to minimize financial

risk and also improves safety by improving accident prevention. The severe accident

protection incorporates the regulatory policy level guidance and provides increased assurance

of containment integrity and low leakage of radioactivity during a severe accident.

The LDB Evaluation Approach and the SMB Evaluation Approach are the methods, criteria and assumptions which are to be used by the Plant Designer in analyzing those portions of the future CANDU design which are required to meet the LDB and SMB, respectively. The main distinction between the LDB Evaluation Approach and the SMB Evaluation Approach is the fact that the former requires conservative design methods and acceptance criteria agreed to by the regulatory agency. The methods and criteria generally are subject to rigorous demonstration through peer review and testing. The SMB Evaluation Approach, on the other hand, is a best-estimate evaluation which, in the case of containment performance, for example, confirms the adequacy of the margin for severe accidents.

2.6 REGULATORY STABILIZATION

The regulatory stabilization policy is to achieve high assurance of licensability by

resolving open licensing issues, establishing acceptable severe accident provisions, and

achieving a design consistent with regulatory criteria. This policy is to be implemented

throughout the design and construction of the plant. The Plant Designer is required to

produce a design which is consistent with applicable regulations and regulatory guidance.

2.7 PLANT STANDARDIZATION

The future CANDU design recognizes the importance of standard designs.

Accordingly, design requirements which can form the technical foundation for standardized

- 7 -

detailed designs have been developed. Key plant features will be specified in sufficient detail in the FCRED to permit meaningful standardization.

2.8 PROVEN TECHNOLOGY

This policy is that successful, proven technology be employed throughout the plant,

including system and component designs, maintainability and operability features, and

construction techniques. The intent is to utilize the large experience base from operating

plants in order to minimize the risk to the plant owner, assure credibility and control of

schedules and costs, and ensure that a power plant prototype is not required.

Proven technology is defined as structures, systems, components, and design and analysis techniques with the same characteristics and materials, working conditions, and environments as those which have been successfully demonstrated, preferably through several years of operation in existing plants. In other areas the designer is to review existing data bases of PHWR operating experience to identify both positive experience as well as causes of significant events and unplanned outages, and to incorporate appropriate features in the plant design.

The proven technology policy encourages the use of advanced technology, especially in areas where there is a need to solve known problems or an opportunity for simplification, and where the advanced technology is proven. Assuring that advanced technologies are proven will typically require testing and/or proven successful use in other applicable industries.

2.9 MAINTAINABILITY

The maintainability policy is that the plant be designed from the outset to make the plant readily maintainable over its life. This includes providing standardization of components, designing equipment to minimize maintenance needs, designing to reduce occupational exposure, and designing to facilitate those maintenance needs which do exist. Such needs include activities to support inspection, test, repair, and replacement of equipment and systems over the plant life and assuring that adequate access, laydown space, tooling and services are provided as part of the basic plant design.

2.10 CONSTRUCTIBILITY

The specific, enforceable technical requirements in this area are to be included to

provide high assurance of success. Several such requirements are:

• Constructibility is to be explicitly considered in the design to enhance productivity and

assure known problems are addressed e.g., provide space and arrangement for construction

work and eliminate features which have caused major construction problems such as use of

unrealistic construction tolerances.

• Construction planning, erection, and installation activities shall maximize the use of

- 8 -

advanced techniques. Provisions for extensive modular construction shall be incorporated in

plant design at an early stage of design development. A schedule risk evaluation shall be

made for large, complex, modules to assess the potential effect on sequencing and fitup

with adjacent installations due to any possible delays.

• The overall schedule is to be developed jointly by the Constructor, Plant Designer, and

Startup Test organizations utilizing inputs from the principal suppliers and subcontractors.

Work progress shall be monitored and controlled so that corrective actions can be taken to

resolve problems and maintain the schedule milestones. The schedule shall be updated as

work progresses to realistically reflect the actual work status.

• Major design documents required for the first concrete placement shall be issued before

construction begins.

2.11 QUALITY ASSURANCE

The responsibility for quality design and construction work rests with the personnel

and management of the Plant Designer and Constructor organizations actually performing the

work. Further, an effective and adequate Quality Assurance (QA) Program will be established

and implemented to independently verify that the line organizations are performing work that

meets the defined QA requirements. The QA Program emphasis in audits and other QA

activities will be on performance (vs. being strictly compliance oriented).

2.12 SABOTAGE PROTECTION

Sabotage of nuclear power plants could potentially initiate events which challenge

safety systems or which prevent safety systems from operating. The sabotage protection

policy is to provide the following from inception of the design;

• A plant with built-in resistance to sabotage and reasonable capability to mitigate acts of

sabotage; • Additional sabotage resistance through the plant security system; • An overall design which integrates consideration of sabotage protection along with safety,

operability, and cost.

The built-in sabotage design features shall include physical separation of redundant

divisions and groups of safety systems. The plant security system shall include access

control and intrusion detection, a plant security organization, and plant operating procedures

and personnel practices which consider sabotage protection needs. The improved design is

achieved by requiring that the design of the plant security system be integrated with

finalizations of plant arrangement, safety system separation, and building structural design.

2.13 GOOD NEIGHBOUR

The good neighbour policy is that the plant be a good neighbour to its surrounding

environment and population. Substantial improvement in this regard shall be provided

compared to existing plants. To implement this policy, specific design requirements to limit

- 9 -

radioactive releases to the environment shall be defined.

It is also part of the good neighbour policy that the future CANDU unit be designed

to be an asset to the community in which it is located. This is to be provided through

requirements which provide a technical basis for safe and secure operation, favourable

economics and resulting cost of service compared to competing alternatives and non-intrusive

emergency planning.

2.14 ECONOMIC POLICY

The future CANDU NPP will be designed so that it has a significant economic

advantage compared with other power plant alternatives available in the same time frame.

The economic advantage is considered necessary in order to make the future CANDU NPP

attractive to prospective plant investors, given the perceived investment of a new nuclear

power plant. Implementing this policy necessitates that design requirements be specified

which will assure control of construction and operating costs. Therefore, great emphasis has

been placed on constructibility, simplicity, design margin, and other requirements which will

provide confidence that the construction schedule can be met, that licensing approval will be

obtained, that operating cost will be controlled, and that the plant design availability target

can be achieved.

- 10 -

Table 2. 1

Future CANDU Safety Foundation

Accident

Resistance

Core Damage Prevention

Mitigation

Evaluation

Approach

Licensing Design Basis (LDB)

Operating margins to meet regulatory

requirements.

In-service Inspection and Testing

PHTS Integrity.

Safety systems to meet Regulatory Requirements;

- Accident identified from systematic plant review, bounding cases chosen.

- Prevent exceeding regulatory dose limits

Containment and associated system - LOCA Design Basis

- Source Term (1)

Conservative, established design

methods (except for a small number of multiple failure events).

Regulatory approved standards, and acceptance criteria.

Special safety systems must perform

their required functions without credit

for active mitigation by the process

systems.

Conservative licensing analyses of

LDB events.

Meet licensing regulations and regulatory guidance (1).

Safety Margin Basis (SMB)

Increase Margin

Simplicity

System and Component

Reliability

Safety system features for

investment protection;

- Realistic accident sequences

(multiple failures) (2)

Greatly improved MMIS

Containment performance during

severe accident (3)

- Margin beyond LOCA

- Realistic Source Term

Best-estimate evaluations of design

margin and safety margin features.

Utility specified margin and

acceptance criteria.

Credit for both safety-related and

non safety-related equipment.

Realistic severe accident

evaluations supplement by PRA.

Meet regulatory severe accident

policy (3).

1. Future CANDU will comply with TID 14844 CANDU equivalent source term requirements.

2. Treated in CANDU PRA.

3. The emphasis is on mitigating severe accident consequences through use of the moderator

and the shield tank as emergency heat sinks to reduce containment loading.

- 11 -

3. TOP TIER DESIGN REQUIREMENTS

This section contains a summary of the top level design requirements in a narrative

format. The requirements are broken down by function: safety, performance, constructibility,

and design process.

3.1 TOP-TIER SAFETY DESIGN REQUIREMENTS

Safety design requirements are consistent with the three level of safety protection for

the future CANDU defined in the safety policy statement in Section 2. The top level safety

design requirements are broken down by these three levels of protection.

3.1.1 Accident Resistance

Design features are required to reduce the dependence on special safety systems to

achieve safety and protect the utility's investment. The design shall minimize the occurrence

and propagation of initiating events which could lead to larger events and resulting challenges

to safety systems. Top level accident resistance requirements include:

• Simplification shall be emphasized as described in the policy statement in Section 2.

• Ample margin shall be designed into the plant so as to provide a more forgiving and

resilient plant including:

- At least as big a margin to ROP trip as existing CANDU 6 plants;

- Pressurizer inventory and steam generator secondary side inventory larger than existing

CANDU 6 plants;

- Maximum fuel channel exit temperature of 312 °C.

• The DBE shall be 0.24 g.

• The reactor shall be designed so that the prompt reactivity feedback is negative under all

operating conditions.

• Use of best available materials and water chemistry shall be specified based on the

extensive operating experience.

• A greatly improved human-machine interface system shall be provided which will promote

error-free normal operations and quick and accurate diagnosis of off-normal conditions.

• The best proven diagnostic monitoring techniques shall be used for leak detection,

vibration, and other potential problems to minimize failure of rotating equipment and high

pressure systems.

• For most design basis accidents, no operator action is required for about eight hours after

initiation.

• For investment protection purposes, the operator shall have adequate time (30 minutes or

more after indication of the need for action) to act to prevent damage to equipment or to

prevent plant conditions which could result in significant outages.

- 12 -

3.1.2 Core Damage Prevention

Requirements for core damage prevention apply primarily to special safety systems

and include Licensing Design Basis requirements as well as Safety Margin Basis investment

protection requirements. Top-tier core damage prevention requirements are as follows:

• The future CANDU, in addition to its inherent characteristics (notably, the cool, low

pressure moderator in close proximity to the fuel) shall meet applicable regulatory

requirements with regard to special safety system design and analysis of plant and special

safety system response to the design basis transients and accidents.

- Specifically, two fully capable shutdown systems, independent from each other and the

reactor regulating system shall be provided.

- Process system failure coincident with a special safety system failure as a design basis

accident, shall be considered.

- Redundant, diverse and passive emergency sources of decay heat removal shall be

provided.

• For investment protection purposes, the future CANDU design shall be such that the core

can be used for further power operation in case of a postulated near instantaneous break

up to the size of the largest feeder pipe.

• The role of the operator in the future CANDU shall be that of an intelligent situation

manager in the event of off-normal conditions. The plant shall be designed to allow the

operator adequate time to evaluate the plant condition and decide what, if any, manual

action is needed. The plant shall not be designed to lock out the operator and prevent

appropriate manual operation that may be required. The plant shall, however, be designed

so as to prevent operator override of safety system functions as long as a valid safety

system actuation signal exists and the safety system is functioning correctly.

• The mean annual core damage frequency for the design shall be evaluated using PRA and

it shall be confirmed by the Plant Designer. The PRA shall be performed as part of the

conceptual and detailed design and shall be used by the Plant Designer as a tool to

identify and resolve any potential core damage and risk vulnerabilities, as an input to the

Plant Technical Specifications, and as an input to emergency procedure guidelines and

maintenance priorities.

• As part of performing the PRA, the Plant Designer shall define the technical basis to

allow the Plant Owner to assure that risk-significant system, structure, and component

design reliability is maintained and the key PRA assumptions continue to be met

throughout the plant life.

• The technical basis for an accident management program, including emergency procedure

guidelines (EPGs), to assure core damage prevention and mitigation to meet off-site dose

limits, shall be developed by the Plant Designer. The Plant Designer shall translate the

plant design basis into operational limitations and responses which can then be developed

in EPGs and training by the Plant Owner.

- 13 -

3.1.3 Mitigation

Design requirements for accident mitigation include those necessary for the Licensing

Design Basis as well as the Safety Margin Basis requirement to assure protection against

severe accidents. These design requirements are as follows;

• A large, rugged containment building and associated containment systems shall be provided

for heat removal and retention of radionuclides for Licensing Design Basis events.

Containment design pressure shall be based on the most limiting large loss of coolant

accident.

• Licensing Design Basis source term analyses shall be based on LOCA plus LOECC.

• The design shall allow siting at sites available in Korea.

• The Licensing Design Basis shall provide control of hydrogen (source term derived from

LOCA + LOECC analysis) so that the concentration of combustible hydrogen in

containment does not exceed 10 percent under dry conditions.

• The Safety Margin Basis shall consider severe accidents beyond the Licensing Design

Basis, including loss of the moderator as the emergency heat sink, best-estimate hydrogen

generation, realistic source terms, and best-estimate containment loads. Adequate severe

accident protection shall be provided through conservatisms inherent in the design, and

necessary plant features to assure core debris coolability, and avoid detonable concentrations

of hydrogen as necessary to meet the quantitative mitigation requirement stated below.

• Containment systems shall be designed so that regulatory dose limits can be met assuming

a containment design leak rate of not less than 0.2 percent by volume per day (source

term based on LOCA + LOECC).

3.1.4 Supplementary Requirements

• Active special safety systems shall be provided. The systems shall be simplified relative to

current plants so as to make them less complex, to minimize or eliminate realignments to

accomplish safety functions, and to minimize the number of active components, consistent

with other needs.

• For design basis accidents, no credit for manual operator action shall be necessary to meet

dose limits until at least 30 minutes following the initiating event.

• There shall be no fuel damage in the core for at least two hours after sustained loss of

all feedwater with no operator action.

• The plant shall be capable of withstanding a loss of off-site and on-site AC power for up

to eight hours without fuel damage.

• There shall be two independent and diverse on-site sources of emergency AC power.

• To prevent or mitigate common-cause events such as earthquake, fires and missiles, the

two group approach shall be followed.

- 14 -

3.2 TOP-TIER PERFORMANCE DESIGN REQUIREMENTS

The top level performance requirements presented in this section have been grouped

into five major categories. The first category presents required plant characteristics, such as

rating and design life. The second category presents maneuvering and transient response

requirements, such as startup and shutdown requirements. The third category presents

reliability and availability requirements. The fourth category contains operability,

maintainability, and surveillance testing requirements. The fifth category presents top tier

requirements for instrumentation and control systems.

3.2.1 Plant Characteristics Requirements

The top-tier requirements for plant characteristics are as follows:

• The plant shall be designed to operate for 60 years. Over this life span, components will need to be replaced, and special attention will need to be paid to material issues such as fatigue, corrosion, thermal aging and radiation embrittlement effects. Therefore, the design shall include features to permit component replacement within the design availability requirements and shall include analyses and data necessary to support the design life of materials.

• The plant should be capable of operation using on power refueling.

• Fuel mechanical design should be capable of assembly average bumups of at least 10 MWD/KgU.

• The plant shall be designed and constructed so that low level radioactive dry and wet waste volume, suitable for shipment off-site, shall be minimized.

• Wet storage capacity for the spent fuel resulting from five years of operation plus one core off-load of fuel shall be provided. This will be supplemented by the dry storage provision.

• The plant shall be designed and constructed so that occupational radiation exposure can be less than 100 man-rem/year averaged over the life of the plant.

3.2.2 Maneuvering and Transient Response Requirements

The top-tier requirements for maneuvering and non-accident transient response are

as follows:

• The plant shall be designed to provide overpressure protection.

• The plant shall be designed to meet the load following requirements including those for

Korea.

• The plant shall be designed to satisfy a 10 percent of rated power step demand increases

or decreases within ten minutes between 15 percent and 100 percent of rated power.

• The plant shall be capable of a generator load rejection from 100 percent power or less,

without reactor or turbine trip, and be able to continue stable operation with minimum

house electrical loads.

- 15 -

3.2.3 Reliability and Availability Requirements

The following top-tier reliability and availability requirements apply'-

• The plant shall be designed for an annual average availability of greater than 90 percent

over the life of the plant.

• The plant shall be designed to achieve the following outage durations:

- Planned Outages: 21 days/year.

- Minor Outages: less than 5 days/year.

- Major Outages: less than 180 days/10 years.

• The plant shall be designed to limit the number of unplanned automatic trips to be less

than one per year. In response to this requirement, the plant shall utilize a minimum

number of plant variables for reactor trip signals consistent with plant safety and shall

provide increased margin between the normal operating range and the trip set point of

safety variables so that the number of plant trips resulting from normal operation activities

is minimized.

3.2.4 Operability, Maintainability and Testing Requirements

The following top-tier requirements for operability, maintainability, and testing apply:

• Ease of operation shall be designed through such features as use of modem digital

technology for monitoring, control, and protection functions, a forgiving plant response to

upset conditions, design margins, and consideration of the environment in which the

operator must perform.

• The design shall incorporate the results of a systematic identification and resolution of

operational and maintenance problems which exist in current plants.

• Consistent with overall' simplification, the number of different types of equipment which

must be specified and maintained, i.e., valves, pumps, instruments, and electrical equipment,

shall be minimized by standardization, subject to diversification needs to avoid common

cause failure.

• The plant shall be designed to facilitate replacement of equipment, including major

components such as pressure tubes and steam generators, within design availability limits.

• Equipment shall be designed to have minimal, simple maintenance needs, and be designed

to facilitate needed maintenance.

• The layout of systems shall consider the maintenance and testing needs for access, pull

space, laydown space, and heavy lifts related to equipment pieces.

• The plant shall be designed so that the environment under which the maintenance and

testing of equipment must be performed provides satisfactory working conditions, including

temperature, radiation dose, ventilation, and illumination.

• The plant design shall include features to facilitate the use of robots for plant maintenance

activities. Such features shall address arrangements to accommodate movement, necessary

access ports in equipment, robot communication needs, and robot storage and

decontamination

- 16 -

• The surveillance tests shall be designed and where possible automated to measure simply

and directly the systems design basis performance parameters, preferably with the plant at

power in order to avoid adding tasks to the planned outage time. Mechanical and electrical

systems shall be designed to avoid plant trips, and plant equipment and layout shall be

designed to facilitate and simplify surveillance testing. The allowable interval between tests

should be increased where justified. Where surveillance tests must be performed during an

outage, the design should assure that the tests will not be in the critical path for the

outage.

• The Instrumentation and Control Systems shall be such that testing and maintenance is

greatly simplified with respect to current plants. For example, self-testing shall be included

and the testing automated to the degree practical.

3.2.5 Instrumentation and Control System Requirements

The top-tier requirements for the I&C Systems include the following:

• The I&C Systems shall employ modern technology, including multiplexing for monitoring,

control and protection functions. Multiplexing is to be used for any function where it-is

appropriate and reduces the cost and complexity of cable runs throughout the plant.

• The I&C Systems shall incorporate design features such as segmentation of major

operation functions, a degree of separation of redundant equipment within a segment, and

fault tolerant equipment to achieve high reliability and prevent propagation of a fault

between redundant equipment and from one segment to another. These features assure

"graceful" failure which allows continued plant operation to the extent practical.

- The I&C Systems design process shall be fully integrated with the remainder of the plant

design. The design process shall provide for iteration among the I&C System and plant

designers and shall use mock-ups, simulator, and operations and maintenance personnel

input in the I&C Systems design.

- The main control room shall be designed on the basis of a specified number of operators

being available for operation of the plant in all modes of operation.

• The main control room shall contain control facilities with display and control devices that

provide organized, hierarchical access to alarms, displays, and controls. The control

facilities shall have the full capability to perform main control room functions as well as

support division of operator responsibilities.

• The main control room shall incorporate modern, computer-driven displays to provide

enhanced operational trending information, validated data, and alarm prioritization and

supervision, as well as diagrammatic normal, abnormal, and emergency operating

procedures with embedded dynamic indication and alarm information. Optionally, extensive

use of data management and computer-aided design (CAD) techniques shall be made to

display piping and instrument (P&ID) drawings at varying levels of detail with updated

equipment status indication.

• The main control room and control station environment, e.g., radiation levels, lighting

levels, HVAC, sound levels, colours, etc., shall provide a comfortable, professional

atmosphere that enhances operator effectiveness and alertness.

- 17 -

• Local and stand-alone control systems shall be designed in the same rigorous way as the

main control stations and will use consistent labelling, nomenclature, etc. Particular

attention is to be paid to visibility, colour coding, use of mirnics, access, lighting, and

communication.

• An integrated, plant wide communication system shall be provided for construction and

operation.

3.3 TOP-TIER CONSTRUCTIBIL1TY REQUIREMENTS

The key top-level requirements for constructibility of the future CANDU can be

separated into three general areas: construction and design coordination requirements,

advanced technology requirements, and planning and scheduling requirements. All

requirements in these areas are oriented toward implementing the constructibility policy of

achieving an improved and effective construction activities.

3.3.1 Construction Duration and Design Completion Requirements

There are several key quantitative requirements on construction duration and design completion. The most important of these is that the design shall be 90 percent complete before placement of structural concrete. The 90 percent complete figure means 90 percent of all plant engineering design documents, including site specific documents but not counting vendor drawings, shall be 100 percent ready to issue for construction, procurement, or other future use. The vendor drawings necessary to allow this 90 percent complete plant engineering must also have been completed.

3.3.2 Construction and Design Coordination Requirements

The key requirements to obtain the needed coordination of design and construction

activity are as follows:

• Plant constructor personnel shall participate in the design process to assure that

constructibility requirements are adequately implemented.

• Design provisions to simplify and facilitate construction and startup shall be explicitly

considered in the design process. Such provisions include good crane and material handling

access, adequate space and access for construction activities, and provision for temporary

construction buildings and equipment.

• Standardized component sizes, types, and installation details shall be provided to improve

productivity and reduce material inventories.

• Realistic construction tolerances shall be specified to minimize unnecessary re-work and to

improve productivity.

• An experience review of previous construction problems shall be performed to assure

lessons learned are addressed in design and construction.

- 18 -

3.3.3 Advanced Construction Technology Requirements

Advanced technology requirements have been specified to support improved

constructibility in two major ways:

• Use of multiplexing in many of the instrumentation and control systems to reduce cable

pulling and thereby to simplify and accelerate construction.

• Modularization of equipment packages and structural elements to take advantage of

improved productivity and reduced labour costs of shop versus field labour. This

modularization in the design shall be accomplished while still preserving the space needed

for maintainability, testing, and other access-related requirements.

3.3.4 Integrated Construction Planning and Scheduling Requirements

Experience with existing construction projects has shpwn the importance of effective construction planning, scheduling, and monitoring. The key top-level requirements in this regard are:

• A detailed living construction plan shall jointly be developed prior to start of construction by the Plant Designer, Constructor, and Startup Test organization, utilizing input from principal suppliers and subcontractors. The plan shall establish the overall approach and provide a basis for developing and assessing schedules.

• Detailed schedules shall also be jointly developed prior to start of construction to integrate the design, procurement, construction, and startup testing activities up to Plant Owner acceptance. The startup testing requirements shall establish the logic for system turnover sequence and schedule including requirements necessary for defining system boundaries, establishing system numbering, and assuring timely turnover.

• Monitoring of the construction process shall be accomplished using quantitative methods appropriate to the particular activity, e.g., number of welds, feet of cable pulls, to make up-to-date assessments of progress and to anticipate where deviations from schedules may occur in time to take appropriate action to resolve problems and maintain schedule milestones. The schedule shall be updated as work progresses to realistically reflect the actual work status.

3.4 TOP-TIER DESIGN PROCESS REQUIREMENTS

This section provides top tier requirements for the process to be carried out in

design including use of the computerized design tools. The design process includes activities

such as development, testing, analyses, preparation of specifications and drawings, models,

reports and support of others as required to complete the licensing, construction, and startup

of the plant and turnover to the operator. The top-level design process requirements are

divided into three areas: design integration, information management and engineering

verification.

- 19 -

3.4.1 Design Integration Requirements

Complete and early integration of all factors important to the plant design is

necessary to minimize the need for redesign and backfit to assure adequate design interfaces,

and to minimize operational difficulties. The following top-tier requirements apply:

• The design process is to be managed and executed as a single integrated process.

Therefore, the requirements have been addressed to the Plant Designer even though the

effort may involve more than one organization (e.g., an Architect Engineer, an NSSS

supplier, and a Constructor).

• The Plant Designer shall prepare design basis documents for each plant system or element

which describe specific design criteria, the design features, and how these features satisfy

the criteria. The documents shall be sufficiently complete that an acceptable design can be

developed and that the potential acceptability and conformance to design requirements can

be judged.

• Interdisciplinary design reviews shall be conducted throughout the design and construction

process. These reviews shall include confirmation that the utility simplification policy is

being emphasized in the design and that all specific simplification requirements are being

addressed.

3.4.2 Information Management System (IMS) Requirements

The main objectives of the IMS requirements are as follows;

• To provide a logical breakdown of the plant into a number of systems and system groups and to use standard identification for all systems, components, facilities, and documentation which can be used for design, construction, and operation.

• To make effective utilization of computer aided design and engineering during design and construction, and after the plant is turned over to the operator.

• To provide for efficient implementation of a project information network.

• To provide an effective means to acquire, store, retrieve and manipulate the documents and data necessary to design, construct, startup, operate and maintain the plant.

• To assure that information needed for construction and operations is available when the plant is turned over to the owner.

3.4.3 Engineering Verification of As-built Conditions Requirements

As part of the design process, the Plant Designer shall identify and perform

necessary engineering verification activities to confirm adequacy of the installation,

specifically:

• Verification activities shall be identified early in the construction and scheduled so that

completed walkdowns and evaluations, as well as any necessary rework, support the

project completion milestones.

• Verification activities shall include a seismic walkdown to verify all key seismic

assumptions such as equipment anchorages and system interactions.

• To the extent practical, the design shall include provisions which avoid the need for

verification walkdowns during construction. Where verification is necessary, the Plant

Designer shall develop procedures, including walkdown objectives and scope, process for

- 20 -

evaluation, and process for resolution of items which do not meet the design intent.

Sampling techniques shall be used in preference to inspections of the total population in

question.

- 21 -

4. SUMMARY OF TOP-TIER DESIGN REQUIREMENTS

A brief summary of top-tier design requirements is provided in the following table.

The top-tier design requirements are categorized by major functions, including safety and

investment protection, performance, design process and constructibility. There is also a

category of general design requirements, such as simplification and proven technology, which

apply broadly to the design. These requirements reflect the policies described above and form

the basis for developing the detailed system design requirements for specific concepts in

FCRED.

- 22 -

Table 4. 1 Summary of Top-Tier Requirements

GENERAL DESIGN

REQUIREMENTS

Plant type and size

Safety system concept

Plant design life

Design philosophy

Plant siting envelope

PHWR, 900-1300 MWe (gross).

Simplified and improved active safety system concepts.

60 years.

Simple, rugged, high design margin, based on proven

technology; no power plant prototype required.

Must be acceptable for most available sites in Korea; 0.24

DBE.

PROTECTION

Accident resistance

Core damage prevention

• LOCA protection

• Core damage frequency

• Station blackout coping

time for core cooling

Design features which minimize the occurrence and severity of initiating event, such as: • Robust margin to ROP trip;

• Adequate time to respond to plant upset conditions through features such as increased steam generator, pressurizer and reserve water tank inventory;

• Use of best available materials.

Design features which prevent initiating events from progressing to the point of core damage.

No fuel damage in unaffected channels for any break up to the

size of the largest feeder pipe.

less than 10~5/ry.

8 hours minimum.

Mitigation

• Containment

• Licensing

• Whole body dose

• Hydrogen generation

Large, rugged containment building with design pressure based

on licensing design basis pipe break.

Existing AECB and KINS Requirements. Realistic source

term shall be utilized in Plant Probabilistic Risk Evaluation.

Less than 25 rem, frequency less that 10"6/ry.

Based on LOCA/LOECC source term for licensing design

basis to produce less than 10% hydrogen in containment.

- 23 -

PERFORMANCE

Design availability Refueling

Unplanned automatic scrams

Maneuvering

Load rejection

Site spent fuel wet storage

capability

Occupational radiation

exposure

90%

on power refueling.

less than 1/year.

load following and cycling capability.

loss of load without reactor trip or turbine trip.

5 years of operation plus one core off load supplemented by

provision of dry storage.

less than 100 man-rem per year.

OPERABILITY AND MAINTAINABILITY

Design for operation Operability features designed into plant, such as: forgiving

plant response for operators, design margin and operator

environment.

Design for maintenance Maintainability features designed into the plant, such as'-standardization of systems and components, equipment design for minimal maintenance needs, provision of adequate access, and improved working conditions.

Equipment access Ready access to equipment.

Equipment replacement Facilitate replacement of components, including steam generators.

INSTRUMENTATION AND CONTROL

Instrumentation and control

system

Current technology, including computer based systems, alarm

prioritization, fault tolerance, automatic testing, multiplexing,

error detection and correction technique, network

communication, open architecture equipment and software

design, object oriented software design and facility for

reconfiguration by operation staff and computer driven

displays.

Operations simplicity One operator shall be able to control plant during normal power operation.

Control centre Human factors engineered to enhance operator effectiveness,

utilizing mockups, simulation, and operator input to design.

24 -

DESIGN PROCESS AND C0NSTRUCTD3ILITY

Design and plan for Develop an integrated plan through plant owner acceptance.

construction

• Construction Period 46 months

(first concrete to in-service)

• Design completion 90% of all plant engineering design documents are complete

requirement before placement of structural concrete.

Design Process

• Design integration • Information management

Manage and execute design as a single, integrated process.

Computerized system and 3-D CAD models to generate and

utilize integrated plant technical data base during design,

construction, and operation.

- 25 -

서 지 ;져。 보 양 λ-11

수행기관보고셔 번호 위탁기관보고서 번호 표준보고서 번호 INIS 주제코드 번호

KAERVTR-647/96

제목/부제 개량형 중수로 원자력발전소 설계요건서(요약)

보고서 작성자 및 부서명 이 득수 (울진5，6호기 기술관리 분야) 외 3 인

발행지 대전 발행기관 한국원자력연구소 발행인 1996. 3

페이지 27 도표 유(0) 무( ) 크기 30 x 19

참고사항

비밀여부 공개(0)， 대외비( ), 급비밀 보고서 종류 기술보고서

위탁연구기관 계약번호

요약 (300단어 내외)

개량형 중수로 발전소 설계요건서(요약)는 한국을 위시하여 차세대 중수로형 발전소에

대한 사용자 요건을 분명하고 완벽하게 기술하고있다. 기술된 요건들은 가압중수로의 경험에 업

각한 실증된 기술을 기초로 하여 범세계적인 현행 요건서에 명시된 설계요건들과 부합시키고자

한다. 나아가서， 이 종합된 설계요건서는 현재 채택가능한 범위 내에서 사용자의 업력을 최대한

포함시키고， 성능과 안전성을 증진시키기 위하여 단순하고， 강력하며 보다 여유 있는 설계를 보

증하고 있다.

본 설계 요건서는 핵증기공급계통과 보조설비계통은 물론 변전소와 송전 선을 연결하

는 회로차단기의 배전반 측에 있는 급전망과의 연계부분까지 망라한 발전소 전체를 대상으로

하고 있다. 또한 본 요건서는 발전소내의 저준위 방사성 폐기물의 처리요건과 사용후핵연료 저

장요건을 포함하고 있으며 소외 폐기물 폐기는 본 요건서에서 취급하지 않았다.

주제명 키워드 00단어 내외)사용자요건， 차세대， 경험， 실증; 요건서， 성능， 안전성， 단순，

강력

- 26 -

BIBLIOGRAPHIC INFORMATION SHEET

Performing Org.

Report No.

Sponsoring Org.

Report No.

Standard Report No. IMS Subject No.

KAER1/TR-647/96

Title/Subtitle FUTURE CANDU NUCLEAR POWER PLANT DESIGN REQUIREMENT

DOCUMENT, EXCUTIVE SUMMARY

Reporter and Department DEUCK SOO LEE (UCN 5&6 Technical Coordination Dept) et al.

Publication

Place Taejon Pub. Org KAERI Pub.Date 1996 3

Page 27 Figure and Table Yes(O) No( ) Size 30 x 19

Note

Classified OpenO), Outside( ), Class( ) Report Type Technical Report

Sponsoring Org.

Contract No.

Abstract (300 words)

The Future CANDU Requirements Document (FCRED) describes a clear and

complete statement of utility requirements for the next generation of CANDU nuclear power

plants including those in Korea. The requirements are based on proven technology of

PHWR experience and are intended to be consistent with those specified in the current

international requirement documents. Furthermore, these integrated set of design

requirements, incorporate utility input to the extent currently available and assure a simple,

robust and more forgiving design that enhances the performance and safety.

The FCRED addresses the entire plant, including the nuclear steam supply system

and the balance of the plant, up to the interface with the utility grid at the distribution side

of the circuit breakers which connect the switchyard to the transmission lines.

Requirements for processing of low level radioactive waste at the plant site and

spent fuel storage requirements are included in the FCRED. Off-site waste disposal is

beyond the scope of the FCRED.

Subject Keyword (10 words) Utility Requirements, Next Generation, Experiences, Proven, Requirement Document, Performance, SAfety, Simple, Robust

27