Regulatory Approach to the Lifetime Management of the Nuclear Power Plants in Korea June 30, 2004...

Regulatory Approach to the Lifetime Management of the Nuclear Power

Plants in Korea

June 30, 2004

Choi, Kyung Woo

Korea Institute of Nuclear Safety

International Conference on 50 Years of Nuclear Power – the Next 50 YearsObninsk/Moscow, Russian Federation

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Contents

Introduction

Current Regulation Related to Life Management

Periodic Safety Review System

Plant Life Management Evaluation Factors

Procedural Requirements for Plant Life Extension

Summary

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Introduction

There are 18 NPPs in operation and 2 NPPs under construction in Korea, since the 1st NPP started its commercial operation in 1978.

9 NPPs have been operating more than 10 years, and Kori unit 1 is approaching its design life of 2008. (Wolsung unit 1: 2013)

Public concern has been increased on the safety of operating NPPs.

Systematic and comprehensive operational safety assessment and plant life management are necessary to maintain a high level of safety

Taking account of improvements in safety standards and practices, the cumulative effects of plant ageing, operating experience, and the evolution of science and technology.

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Status of Nuclear Power Plants in Korea

PlantReactor

Type

Thermal Power (MWt)

TBN Power (MWe)

Operating License Commercial Operation

Kori-1 PWR 1724 587 May, 1972 April, 1978

Wolsong-1 PHWR 2064 688 February, 1978 April, 1983

Kori-2 PWR 1876 650 August, 1983 July, 1983

Kori-3 PWR 2775 950 September, 1984 September, 1985

Kori-4 PWR 2775 950 August, 1985 April, 1986

Youggwang-1 PWR 2775 950 December, 1985 August, 1986

Youggwang-2 PWR 2775 950 September, 1986 June, 1987

Uljin-1 PWR 2775 950 December, 1987 September, 1988

Uljin-2 PWR 2775 950 December, 1988 September, 1989

Youggwang-3 PWR 2815 1000 September, 1994 March, 1995

Youggwang-4 PWR 2815 1000 June, 1995 January, 1996

Wolsong-2 PHWR 2061 700 November, 1996 July, 1997

Uljin-3 PWR 2815 1000 November, 1997 August, 1998

Wolsong-3 PHWR 2061 700 December, 1997 July, 1998

Wolsong-4 PHWR 2061 700 February, 1999 October, 1999

Uljin-4 PWR 2815 1000 October, 1998 December, 1999

Youggwang-5 PWR 2815 1000 October, 2001 May, 2002

Youggwang-6 PWR 2815 1000 July, 2002 December, 2002

Uljin-5 PWR 2815 1000 October, 2003 June, 2004 (Schedule)

Uljin-6 PWR 2815 1000 October, 2004 (Schedule) June, 2005 (Schedule)

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Introduction

Operating license is issued without a fixed term in Korea.

Design life is established in FSAR for the basis of design and safety assessment.

It is ambiguous whether the continued operation beyond the design life is accepted or not in the legal and technical aspects.

Institutional scheme for the plant life extension should be carefully considered in the very near future, considering the remaining life of Kori unit 1 and the time required for the safety assessment.

The technical and economic feasibility studies for the lifetime management of NPPs have been carried out for the last 10 years.

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Introduction

Periodic safety review (PSR) system was introduced and established with sound legal basis in order to evaluate the comprehensive and systematic safety of operating plants.

The PSR scope is based on the safety factors suggested by the IAEA.

The results of PSR with focusing on ageing assessment can be utilized for the life extension.

Nuclear Safety Commission in Korea recommended using the results of PSR in the life extension of NPPs.

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Current Regulations on Life Management

Legal Basis for Regulation

Atomic Energy Act

Enforcement Decree of Atomic Energy Act (Presidential Decree)

Enforcement Regulation of Atomic Energy Act (Ministerial Decree)

Regulation on Technical Standards of Nuclear Installation (Ministerial Decree)

Regulation on Technical Standards of Radiation Protection (Ministerial Decree)

Notice of the Minister of Science and Technology

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Licensing Procedural Requirements

Construction Permit: Early site approval for limited construction work on a proposed

site before the construction permit is issued.

Operating License: No prescriptive limit on the license term: design life specified in

FSAR

Decommissioning: Approval of a decommissioning plan

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Design Requirements Quality Standards

Environmental & Dynamic Effects Design Bases

Qualification Requirements of equipment

Abilities for Test, Monitor, Inspection & Maintenance

Inspection Requirements Pre-operational Inspection

Periodic Inspection

Quality Assurance Inspection

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Requirements on Safety Measures for Operation

Conformance to Technical Specification (TS)

Feedback of Operating Experience

Testing, Monitoring, Inspection & Maintenance of SSCs In-service Inspection (ISI)

In-service Test (IST)

Reactor Pressure Vessel Surveillance

Instruments Calibration

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Corrective Actions & Enforcements

Rectification or supplement according to the results of the pre-operational inspection

Rectification or supplement according to the results of the periodic inspections.

Order to take corrective or complementary measures against inadequate performance of facilities and safety measures for the operation

Order to submit report or documents on their business, and order to take corrective or complementary measures as a result of the inspections

Revocation of operating license or suspension of an operation not exceeding one year

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PSR system Up-to-date Progress

Nuclear Safety Commission (NSC) decided basic framework for the implementation PSR on December 1999.

MOST issued “Implementing guidelines for PSR” on May 2000, after deliberation of NSC.

KHNP submitted PSR plan for Kori unit 1 on May 2000 The 1st PSR on Kori unit 1 had been completed by May 2004. (W

olsung unit 1: in progress)

Atomic Energy Act was revised to adopt PSR system on Jan. 2001, including basic direction and framework for the implementation of PSR Detailed provisions including review scope, method, procedure, a

nd technical standards are included in the Enforcement Decree (Presidential Decree) and the Enforcement Regulation (Ministerial Ordinance) of the Atomic Energy Act.

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PSR system PSR Implementing Method

PSR to be carried out every 10 years after issuance of an operating license

KHNP, the operator of NPPs, has the responsibility of performing the PSR MOST specifies PSR requirements and reviews the PSR results

Review scope is based on the 11 safety factors suggested by IAEA in Safety Series No. 50-SG-O12, and detailed scope may vary depending on plant age① Actual physical condition of the NPPs② Safety analysis③ Equipment qualification④ Management of ageing⑤ Safety performance

⑥ Use of Experience from other NPPs & of research findings⑦ Procedures⑧ Organization & administration⑨ Human factors⑩ Emergency planning

⑪ Environmental impact

☞ The revised IAEA safety guide: Safety Series No. NS-G-2.10 (2003)

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PSR system

PSR Implementing Method (continued) The revised IAEA safety guide on PSR of NPPs:

The safety factors were increased from 11 to 14.– The factor, actual physical condition of the NPPs, was subdivided into

plant design and actual condition of SSC– The factor, safety analysis, was subdivided into deterministic safety a

nalysis, probabilistic safety analysis (PSA), hazard analysis.

These factors have been reflected in the current regulatory system, but further reinforced regulatory system will be developed.

PSR for twin plants having a single FSAR put together into a single report Separately consider the ageing of SSCs and the physical status

of each plant

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PSR system

PSR Process KHNP performs PSR with safety improvements of the plant

through hardware or procedural modifications based on the results, and prepares PSR report.

MOST/KINS reviews PSR results and prepares Safety Evaluation Report with identification of safety issues.

MOST with deliberation by NSC makes a decision on whether continued operation is appropriate or not.

Corrective actions are to be issued including PSA, if necessary.

KHNP implements the corrective actions, if any, and prepares “Implementing Report” for the review by MOST/KINS of the results of the corrective actions.

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PSR Implementing Process

Order corrective actions

Suspend operation

KHNPKHNP MOSTMOST KINSKINS

CompletionCompletion

Implement corrective actions- perform PSA, if necessary

Implement corrective actions- perform PSA, if necessary

<Deliberation by NuclearSafety Commission>

<Deliberation by NuclearSafety Commission>

Prepare Safety Evaluation Report- identify safety issues

Prepare Safety Evaluation Report- identify safety issues

Prepare implementing reportPrepare implementing report Review results of corrective actions

Review results of corrective actions Review PSR resultsReview PSR results

Prepare implementing planPrepare implementing plan Review implementing planReview implementing plan Review implementing planReview implementing plan

Perform PSR- safety improvements- prepare PSR report

Perform PSR- safety improvements- prepare PSR report

Review PSR resultsReview PSR results

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PSR system Technical Requirements; PSR Review Standards

PSR performed based on technical requirements of reactor facilities and the safety measures for the operation of facilities prescribed under the nuclear legislative and regulatory framework Detailed technical requirements are referred to those applied to

the operating license of a NPP issued near the beginning of the PSR

Exemptions may be possible, if the technical requirements are deemed inappropriate to be applied as they are; due to the differences in the design principles of a nuclear reactor,

or due to the differences in the operational characteristics of a

nuclear reactor

Justification for the exemptions should be provided taking account of physical possibility, safety significance and cost-benefit.

PSA could provide useful insights for the justification

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PSR system

Technical Requirements; on Ageing Assessment Review whether plant ageing is being effectively managed so

that required safety margins are maintained and whether an adequate ageing management program is in place for future safe operation of the plant.

Classification and selection of SSCs required for the review

Evaluation of ageing mechanism of SSCs

Effect of ageing on functional capability and safety margin of SSCs

Prediction of future state and time-exceeding acceptance criteria of SSCs

Program for ageing management and mitigation of ageing effects

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PSR system

Technical Requirements; General Technical Criteria

The safety functions of nuclear facilities shall not be impaired by ageing and sufficient safety margin shall be ensured against ageing.

Ageing management program for nuclear facilities shall be established so that safety functions and required safety margins are ensured.

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Factors to be Considered for Life Management

Principles on the Plant Life Management from IAEA INSAG-14: Principles on the Plant Life Management from IAEA INSAG-14: Safety Management of the Operating Lifetimes of NPPSafety Management of the Operating Lifetimes of NPP

Consideration of degradation mechanism from the design stage surveillance, test, inspection, repair and replacement

Comparison with the design basis Maintaining the design safety level of the plant

Monitoring the effects of ageing and reviewing the life limiting equipment

Assessment of the surveillance results and anticipation of possible repair or replacement work

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Review of the reference safety levels Improvement of reference safety levels as far as reasonably

practicable and the preferable achievement by step

Safety review Effective ageing management and possible evolution of

reference safety level

Infrastructure support for safe management Maintaining sufficient staff with adequate competence

Handling major organization changes to avoid any significant impact on safety

Maintaining excellence in operation by use of self-assessment and peer reviews

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Basic factors for Life Management (Life Extension) Following basic factors, as a tentative, were identified for life

management (life extension) considering IAEA principles for operating lifetime management, License Renewal process in the U.S., and practices of plant life extension using PSR in Europe.

① Consideration of ageing mechanism in design② Maintenance of design safety level③ Upgrading of safety level with current safety standards④ Utilization of new technologies and operational experiences⑤ Evaluation and monitoring of ageing⑥ Plan for repair and replacement⑦ Integrated safety review⑧ Evaluation of environmental effects⑨ Infrastructure support fore safe management⑩ Complement of safety-related documents

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Comparison of Basic Factors for Life Management with PSR & License Renewal

Basic factors PSR safety factor License renewal

Consideration of ageing mechanism in design

Actual condition, safety performance, ageing, qualification, procedures

License renewal(Technical information)

Maintenance of design safety level

Actual condition, safety analysis, safety performance

License renewal(Technical information)

Reflection of current safety regulation

Safety analysis Back-fitting rule

Utilization of new technologies and operational experiences

Operational experiences and R&D results

Back-fitting rule

Evaluation and monitoring of ageing

Ageing, actual condition License renewal(Technical information)

Plan for repair and replacement

Qualification, ageing, procedure, safety performance

10 CFR regulations

Integrated safety review PSA (Optional) Probabilistic risk assessment (PRA) regulation

Evaluation of environmental effects

Environmental effects(monitoring only)

License renewal(Environmental report)

Infrastructure support for safe management

Organization, human factor 10CFR regulations

Complement of safety-related documents

Procedure, no requirement on complement of FSAR (TS)

License renewal reporting rule

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Relation between PSR & Life Management The basic factors for life management are considered in the

current PSR system except following items:

PSA

Evaluation of environmental effects

Complement of FSAR (including TS) in safety-related documents

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Comparison with Basic Factors for Life Management The basic factors for life management were partially considered in

the License Renewal process in the U.S., except following items that are considered in the other regulations in 10CFR.

Reflection of Current safety Regulation: Back-fitting Rule (10CFR50.54, f)

Utilization of New Technologies & Operational Experiences: Back-fitting Rule

Plan for Repair & Replacement: Maintenance Rule (10CFR50.65)

Integrated Safety Review: PRA Regulation (10CFR50.34 f, 1, i)

Complement of Safety-related Documents: Maintenance of Record (10CFR50.71)

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Procedural Requirements for Plant Life Extension

Possible models to be considered

Approval of continued operation through the amendment of operating license

Continued operation with PSR results

Establishment of operating license term

For any models, the PSR results can provide useful

information for the decision of continued operation.

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Summary

The PSR system was introduced and well established in the legislative aspects for the comprehensive and systematic safety evaluation of operating plants.

The identified basic evaluation factors were used effectively for the evaluation of the plant life management.

The PSR could be utilized in determining the plant life extension by adding PSA, evaluation of environmental effects and complement of FSAR (including TS) in safety-related documents.

Three possible models for the life management (life extension) of the NPPs were suggested.

※ This study was carried out for the support of the government decision-making to establish the plant life management (life extension).

Regulatory Approach to the Lifetime Management of the Nuclear Power Plants in Korea June 30, 2004...

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