Preliminary Consideration on Safety

Criteria of TMSR

Xiaobin XIA Department of Nuclear Safety and Engineering

Shanghai Institute of Applied Physics

Chinese Academy of Sciences

2012-10-29

THORIUM ENERGY CONFERENCE 2012, Shanghai, China ,October 29 – November 01, 2012

2012/11/2

Research Reactors in TMSR project Phase I

TMSR (Solid): Thorium Fluoride-Salt-Cooled High-

Temperature Reactors (TFHR)

2MWth (2011-2015 )

TMSR (Liquid): Thorium Molten Salt Reactor ,

2MWth (2011-2017 )

Different

types of

reactors

Different

Safety

criteria

2012/11/2

Contents

Basic Safety Objectives of TMSR

TMSR License Basis and Licensing Process

Safety Issues and Design Criteria for 2MWth TFHR

Safety Issues and Design Criteria for 2MWth TMSR

Basic Safety Objectives of TMSR

Public health and safety

*Reduce the risk from releases of radioactivity to acceptable

levels

Staff health and safety

*Provide a safe working environment and reduce risk of injury

*Comply with regulatory requirements and promote worker

protection

Environment protection

*Provide a design that complies with regulatory requirements

*Design, construct, commission, operate and decommission

the plant in a way that preserves environmental quality

TMSR License Basis

Based on nuclear power plant guide series in

nuclear safety guides (for research reactor);

The terms from PWR not applicable to TMSR will

be reviewed and studied

Establish a Design criteria of TMSR

Environmental protection and Nuclear Safety Guides and Regulations

Authorities:

*Ministry of Environmental Protection of the People’s Republic

of China

*National Nuclear Safety Administration

《Safety Guide for Research Reactor Design》(HAF201)

《 Safety Guide for Research Reactor Operation 》(HAF202)

IAEA No.NS-R-4 “Safety of Research Reactors”

IAEA No.NS-G-4.2 “Maintenance, Periodic Testing and

Inspection of Research Reactors”

IAEA SS No.35-S1

IAEA SS No.35-S2

Licensing Based on National Nuclear Safety Administration

Five Phases to get License for a New Research Reactor

License to site prepare;

License to construct;

License to commissioning

(including first fuel loading

license)

License to operate

License to decommission

Environmental assessment

for site selection;

Environmental assessment

report

Preliminary safety analysis

report

Revised preliminary safety

analysis report

Review of final safety

analysis report

Licensing Based on National Nuclear Safety Administration

Five Phases to get License for a New Research Reactor

Environmental

assessment

Focus on information on

protection accidents and

incidents

Safety analysis

Focus on proposed quality

assurance program for

design, health, safety,

security and environmental

protection

Overlapping procedure

General Considerations on Frame Work of Safety Design for TFHR

Existing Licensing Process

Applicabibility of HTGR and FBR

(Experiences in HTGR and FBR research reactors in

China and national-approved Safety Criteria)

Setting 2MWth TFHR Safety Criteria

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Safety Elements for 2MWth TFHR

High temperature material

Nuclear-grade graphite)

TRISO fuel

Nuclear critics

Thermal-fluid dynamic

Severe accidents

Structure

I & C

Radiation safety

Transportation

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Safety Issues for High Temperature Material

Chemical attack and FP release

Internal metallic support structures

and components integrity

Core support structure integrity

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Safety Issues for Nuclear–grade Graphite

Functionality of active shutdown systems

Core coolant bypass leakage

Integrity of core structure and support structure

Max. temperatures

Graphite caused dust to accidental release

Potential reactivity events

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Safety Issues for Fuel Performance

TRISO coated fuel particle behavior

(manufacture defects, operation failures and FP

release from Th fuel )

Accident source term

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Safety Issues for nuclear Critics

Passive shutdown during heat-up events

Reactivity addition and prompt supercritical

reactivity pulse events

Transient and accident shutdown margins

Pebble burn-up and fast affluence

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Safety Issues for Thermal Fluid Dynamics

SSC failures at high temperature and it margins

SSC failures due to chemical attack

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Safety Issues for Severe Accident

Elevated failure rate events

FP transport mechanism and behavior

Containment bypass or failure

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Safety Issues for I&C

Extensive use of automation for process control

Controlling multiple modules

Failures must not prevent performing intended

safety function

General Considerations on Frame Work of Safety Design for TMSR

Existing Licensing Process

Applicabibility of Na-FBR

Experience learn from ORNL and experiments

Setting 2MWth TMSR Safety Criteria

Key Issues of Safety for TMSR

Safety principle and decision of safety

design basis

Classification of the events

Acceptance criteria

Major Differences in Safety Guides between PWR and TMSR

Acceptable fuel design limits

Temperature coefficient

Reactivity-initiated event

Reactor shutdown system( control rod and fuel salt

drain)

Residual heat removal system

Reactor coolant make-up system

Emergency core cooling system

Reactor containment isolation valve

Fuel handing system

Radioactive wastes treatment systems

General Safety Design Considerations for TMSR

Design considerations against Natural Phenomena, External

man-induced Events, internal Missiles, Fire, Environmental

Condition

Design considerations against Operator’s Actions

Reliability from design based on redundancy, diversity and

independency

Approval of Applied Codes and standards for design, selection

of materials, fabrication and inspection of safety function SSCs

Seismic analysis and intensity computation of reactor block

structure

Seismic appraisal of control rod drive lines

Preliminary Considerations on Key Issues Against Natural Phenomena for TMSR

Seismic analysis of fuel

Seismic analysis and

intensity computation of

reactor block structure

Seismic appraisal of

control rod drive lines

Setting

appropriate

seismic

categories

Preliminary Considerations on Key Issues Against Abnormal Transients in TMSR

Fuel design

performance, design

limits and conditions

Demonstrate the

performance of fuel and

pipe system

Structure material

performance

Safety limit of fuel

temperature (ex. Peak T)

Safety

criteria for

abnormal

transients in

TMSR

Preliminary Considerations on Key Issues Against Accidents in TMSR

Gas radiation monitoring system

Monitoring measures for the events

such as fuel pipe blockage

Radiation control in maintenance for

TMSR

Local blockage events in several

transient accidents

Accidental decay heat removal system

Engineered safety systems design

with consideration of containment for

high temperature high radiation

Safety

criteria for

accidents in

TMSR to

avoid large

release of

radioactivity

Preliminary Considerations on Key Issues Against Severe Accidents in TMSR

Accident analysis

approach for TMSR

Review on Acceptance

criteria for Severe

accidents

Applicability of DBAs

Concept in PWR and

Possible Severe

Accidents

Safety

criteria for

Severe

Accidents in

TMSR

Preliminary Considerations on Key Issues to Establish Reliability of Safety Analysis

for TMSR

Evaluation of the codes

used for accident

analysis (Current,

21codes for this purpose

are from PWR safety

analysis issues)

Development of analysis

code for TMSR

Establish

reliability for

safety

analysis for

TMSR

Summary

Licensing Procedure Based on National

Nuclear Safety Administration

General Safety Design Considerations for

TMSR to achieve the Basic Safety

Objectives of TMSR based on China

National Regulations

Key Issues of safety analysis and Safety

Criteria for TMSR

Thank you for attention !