Transcript TITRE / CHAPITRE

The Vision of
the European Sustainable Nuclear Energy
Technology Platform
Strategic Research Agenda
on
the Safety R&D for GEN-IV Reactors
G.B. Bruna, IRSN
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The Sustainable Nuclear Energy
Technology Platform
SNE-TP
Strategic Research Agenda - SRA
C.F.LWR
GEN-IV
HTR
Ad. F.C. FRS
Materials
Codes & Standards
C-C. A
Modelling
Fuel
Safety
R. Infr.
Educ.–Tr.
SFR LFR GFR ADS
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Strategic Research Agenda
Safety
• Objective
• ● This presentation is aimed at summarizing the
content of the SRA Sub-Chapter “Safety”, mainly
focusing on GEN-IV aspects.
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Strategic Research Agenda
Safety
• Context
• Very effective collaboration among Contributors
(35 from 8 countries and 20 organizations),
• Many Contributors have participated in some
selected parts only,
• In general, Contributors for Current and
Advanced and Innovative Fission Reactors are
different.
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Strategic Research Agenda
Safety
Summary of the SRA Safety Sub-Chapter
Forewords
Uncertainty analysis and “safety
margins”: two cross-cutting topics
safety research
●
Current Reactors
●
Advanced and Innovative Fission
Reactors
●
●
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for
Strategic Research Agenda
Safety
•
The connection between safety research and regulation is
mandatory in the nuclear technology.
•
Safety research has to accompany nuclear installations
throughout all phases of their life, from concept
definition, through design, licensing, construction and
operation, up to decommissioning.
•
Even if the excellent performance record of existing
installations might suggest that a high safety level can be
achieved without new huge research efforts,
consciousness of research needs should be maintained,
● focusing on new trends,
● supporting public information and training.
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Strategic Research Agenda
Safety
•
Anticipatory research should look ahead to safety
questions that may arise in the future, due to changes in
the design and operating-mode, and the appearance of
new concepts, such as the GEN-IV;
•
The role of the future research should foster in an
improved international cooperation to promote achieving
common understanding of the safety and its standards,
mainly when dealing with the advanced and innovative
concepts which are intended to:
–
–
•
• intrinsically eliminating severe accidents from occurring,
• reducing either their probability or the level of their
expected consequences.
This is done by design, not necessarily by addition of
safety systems, which requires integrating since the
beginning of the conceptual phase, the deterministic and
the probabilistic approaches.
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Strategic Research Agenda
Safety (Current Reactors)
Priority topics for action (short-term within the FP7)
[issues to be either implemented or reinforced]
Current Reactors 1/3
-Reactor Physics and Dynamics
-Thermal-Hydraulics
-Criticality
-Nuclear Fuel
- Human and Organisational Factors
- I&C and Electrical Systems
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Strategic Research Agenda
Safety (Current Reactors)
Priority topics for action (short-term within the FP7)
[issues to be either implemented or reinforced]
Current Reactors 2/3
- Aggression and Hazards
In recent years, new threats are coming up forcing to focus
not only on internal hazards, but also on the destructive
action of external agents including the time.
When assessing the safe behavior of a system, a component
or an equipment, its robustness and resistance to the agingrelated phenomena and to all kind of external aggressions is
to be demonstrated, including
◊ Flooding,
◊ Extreme whether condition,
◊ Seism,
◊ Fire
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Strategic Research Agenda
Safety (Current Reactors)
Priority topics for action (short-term within the FP7)
[issues to be either implemented or reinforced]
Current Reactors 3/3
- Plant Simulation
- Severe Accidents
- Emergency Management .
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Strategic Research Agenda
Safety (Advanced and Innovative Reactors)
Advanced and Innovative Reactors
Advanced and innovative reactors encompass a
variety of different designs and operating modes.
They span a very large set of configurations,
including small and large size cores, fast-neutron
and moderated spectra, gas, water and liquid
metal cooling, each one matching more or less
completely and comprehensively the objectives of
the GEN-IV roadmap (GIF).
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Participants in the G.I.F.
People’s Republic of China
•Economy:
- Natural Resources,
- Fuel cycle;
•Safety;
•Operability;
•Environmental impact:
- Severe Accidents,
- Emergency - Crisis,
- Wastes.
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Russian Federation
The Generation IV System Family
 HTR/VHTR
SFR
GFR
 SFR
 GFR
 LFR
LFR
 MSR
 SCWR
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MSR
SCWR
HTR/VHTR
The Sustainable Nuclear Energy
Technology Platform
SRA
MSR
SCWR included in LWR Chapter, as an evolutionary concept
HTGR – VHTGR accounted for as a multi-energy system
Fast Neutrons Reactors :
LFR,
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GCR,
SFR,
ADS not part in the GIF
Strategic Research Agenda
Safety (Advanced and Innovative Reactors)
Advanced and Innovative Reactors
Natural resource optimization and waste minimization
are goals more likely affordable for systems with fast
neutron flux, such as SFR - Sodium Fast Reactor -, GFR
- Gas Fast Reactor - and LFR - Lead Fast Reactor -.
Graphite moderated, gas cooled high temperature
reactors such as the Very High Temperature Reactor
(V/HTR) are more likely to be inherently safe;
they also have the best potential for a diversified
energy production (electricity, but also
industrial heat and hydrogen).
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Strategic Research Agenda
Safety (Advanced and Innovative Reactors)
Operating experience should contribute to
identify crucial needs for Advanced and
Innovative Systems research,
All the modifications adopted for Current
Reactors and the associated safety assessments
should entail research, including code
development and experimental activity.
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Strategic Research Agenda
Safety (Advanced and Innovative Reactors)
Advanced and Innovative Reactors
Nuclear Reactors are presently facing a very open
landscape as regards the industrial maturity of
concepts.
That is very challenging from the safety point of
view, because the safety assessment is strictly tied
to design features, the details of which are hardly
disclosed and remain widely unknown for the
most concepts at the present stage of
development.
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Strategic Research Agenda
Safety (Advanced and Innovative Reactors)
SFR 1/3
● Specific R&D efforts on design features should enable to
practically preclude any significant energy release in case of
Severe Accident,
● That should be searched for through adoption of
optimised core design features such as the geometry of the
fuel subassembly, the relative volume fraction of core
materials, the density of heavy metal within the fuel and the
possible use of light materials to moderate neutrons and
increase the Doppler Coefficient.
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Strategic Research Agenda
Safety (Advanced and Innovative Reactors)
SFR 2/3
● Other core desirable features for enhanced safety include
reducing reactivity swing and increasing temperature
margins,
● The mechanical behaviour of the core and specific design
options are to be carefully investigated so as to minimise the
risk of core compaction,
● Innovation in core instrumentation and surveillance
should allow for early detection of abnormal situations.
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Strategic Research Agenda
Safety (Advanced and Innovative Reactors)
SFR 3/3
● Sodium technology risk, could be minimized through
substituting conventional steam turbine energy conversion
systems with gas turbine and Brayton cycle conversion,
● The merit of innovations in the reactor design to enhance
safety is to be assessed through normal and accidental
operating transient analyses in terms of robustness of the
safety approach.
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Strategic Research Agenda
Safety (Advanced and Innovative Reactors)
LFR
GFR
● The exclusion approach should be fully discussed and
validated and the Risk Informed methodology applied all
along the pre-conceptual design phase,
● A list of Design Basis Accidents –DBA list- should be
established for safety and margin assessment.
● To cope with any potential danger situation, suitable
passive or active systems should be implemented, if needed.
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Strategic Research Agenda Safety (Advanced and
Innovative Reactors)
V/HTR 1/3
● Industrial heat generation process requirements would
be quite different from electricity generation ones, and
much more versatile, which will demand a high flexibility of
the nuclear heat source; however competitiveness of
nuclear energy is usually achieved via standardisation,
● Competitiveness and flexibility requirements will have to
be reconciled through a conceptual design phase.
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Strategic Research Agenda Safety (Advanced and
Innovative Reactors)
V/HTR 2/3
● Several safety systems, relying on intrinsic properties of
materials and system arrangements as well as on active
devices, have been already studied during the exploratory
phase, such as the core cooling function in tight
relationship with the LPA - Loss of Pressure Accident-; the
other safety functions should be analyzed in accordance to
the DBA list,
● To cope with any potential danger situation, suitable
passive or active systems should be implemented.
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Strategic Research Agenda
Safety (Advanced and Innovative Reactors)
V/HTR 3/3
● Safety challenges are raised by the coupling with
conventional energy-production facilities, which may
propagate instability and perturbations to the reactor,
through intermediate heat exchangers.
● The demonstration of the feasibility of the coupling of
the reactor with process heat applications and cogeneration
is actually the main challenge for the short term for
reactor-systems such as the V/HTR.
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Strategic Research Agenda
Safety (Advanced and Innovative Reactors)
●
Major Safety concerns for GEN-IV
•
Minimizing the risks attached to the liquid metal
coolant (sodium; lead, …),
Practically precluding large energy release in case
of severe accident (even hypothetical),
Minimizing the system vulnerability to external
events and aggressions,
Assessing the impact of MA -Minor Actinidesbearing fuels,
Diversifying the safety systems (e.g., decay heat
removal),
Developing an improved instrumentation for early
detection of abnormal situations,
Developing an improved instrumentation and
techniques for in service inspection and repair.
•
•
•
•
•
•
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Strategic Research Agenda
Safety (Advanced and Innovative Reactors)
The relevant R&D activity can be grouped in
several main fields of endeavour
●
•
•
•
•
•
•
Core Physics and Simulation,
Residual Heat Removal,
Fuel Integrity,
Fission Product Release,
Reduction of Major Risk of a Broad and
Severe Damage of the Core,
In Service Inspection and Repair.
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Strategic Research Agenda
Safety (Advanced and Innovative Reactors)
Concluding Remarks 1/4
• The need for new experimental and simulation tools, aimed
at sustaining safety analyses, should be focused on current
reactor needs with GEN-IV as a definitely new perspective in
view;
• Research hardly accommodates uncertainties and
breakthroughs, and must enjoy continuity to maintain its
effectiveness and usefulness;
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Strategic Research Agenda
Safety (Advanced and Innovative Reactors)
Concluding Remarks 2/4
The simulation tools should be conceived and the
experimental results should be presented in such a way as:
◊ to be really user friendly,
◊ to support their adoption and, as a consequence,
their dissemination among users and countries,
◊ to captivate confidence on the capability to
manage nuclear technologies and handle unexpected
phenomena and events.
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Strategic Research Agenda
Safety (Advanced and Innovative Reactors)
Concluding Remarks 3/4
• The need for keeping a suitable experimental capability for
safety assessment is to be claimed;
• Safety assessment cannot avoid a convenient experimental
support, for investigation of physical phenomena, validation
of computation chains, training and keeping competence
alive;
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Strategic Research Agenda Cross-cutting Activity
Safety (Advanced and Innovative Reactors)
Concluding Remarks 4/4
• Today, the public acceptance plays a key role and may
strongly affect the profitability of an investment in the
nuclear field;
• The cost of experimental activities calls for participation of
partners at the international level;
• Extensive information of the public on safety R&D can
contribute significantly
to increase confidence and acceptance,
to attract newcomers to the field,
to guarantee the necessary financial support.
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