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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
2012/11/2
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
2012/11/2
Safety Issues for High Temperature Material
Chemical attack and FP release
Internal metallic support structures
and components integrity
Core support structure integrity
2012/11/2
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
2012/11/2
Safety Issues for Fuel Performance
TRISO coated fuel particle behavior
(manufacture defects, operation failures and FP
release from Th fuel )
Accident source term
2012/11/2
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
2012/11/2
Safety Issues for Thermal Fluid Dynamics
SSC failures at high temperature and it margins
SSC failures due to chemical attack
2012/11/2
Safety Issues for Severe Accident
Elevated failure rate events
FP transport mechanism and behavior
Containment bypass or failure
2012/11/2
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 !