| PAGE 1 C. Poette, CEA, FR13 Conference, Paris, March 2013P. GUEDENEY CEA | 22 Novembre 2012 FR13 Conference, Paris, March 2013 | PAGE 1 CEA | 10 AVRIL 2012 Gas Cooled Fast Reactors: recent advances and prospects P. GUEDENEY CEA | 22 Novembre 2012 | PAGE 1 C. Poette a , P. Guedeney b , R. Stainsby c , K. Mikityuk d , S. Knol e a CEA, DEN, DER, F-13108 Saint-Paul lez Durance, CADARACHE, France. b CEA, DEN, DEC, F-13108 Saint-Paul lez Durance, CADARACHE, France. c AMEC Knutsford UK d PSI Villigen Switzerland e NRG Petten Netherlands
Transcript
| PAGE 1
C. Poette, CEA, FR13 Conference, Paris,
March 2013P. GUEDENEY CEA | 22
Novembre 2012
FR13 Conference, Paris, March 2013
| PAGE 1 CEA | 10 AVRIL 2012
Gas Cooled Fast Reactors:
recent advances and prospects
P. GUEDENEY CEA | 22 Novembre 2012 | PAGE 1
C. Poettea, P. Guedeneyb, R. Stainsbyc, K. Mikityukd, S. Knole
aCEA, DEN, DER, F-13108 Saint-Paul lez Durance,
CADARACHE, France.
bCEA, DEN, DEC, F-13108 Saint-Paul lez Durance,
CADARACHE, France.
cAMEC Knutsford UK
dPSI Villigen Switzerland
eNRG Petten Netherlands
| PAGE 2 C. Poette, CEA, FR13 Conference, Paris, March 2013
Gas Cooled Fast Reactors: contents
Contents
1) Introduction
2) GFR fuel element
3) Core design optimization
4) System Design
5) Safety Aspects
6) GFR R&D Program
7) Conclusion
| PAGE 3 C. Poette, CEA, FR13 Conference, Paris, March 2013
Gas Cooled Fast Reactors: Introduction
GFR : a longer term option allowing to combine Fast spectrum & Helium coolant benefits
Safety (Helium coolant) • No threshold effect due to phase change, no void reactivity effects,
no chemical reaction • Optical transparency: potential for In Service Inspection,
Temperature measurement capabilities
Competitiveness • High temperature potential for:
- High energy conversion efficiency (45-48%) - A broad range heat industrial applications (process heat, hydrogen, synthetic hydrocarbon fuel production)
Fuel management (fast spectrum) • Efficient use of natural resources: Pu generation • Potential for ultimate waste minimization: multi-recycling of all
actinides
H2O 150 bar
He-N2 65 bar He
70 bar
850°C
400°C
820°C 535°C
32°C 178°C 362°C
565°C
Electrical grid
| PAGE 4 C. Poette, CEA, FR13 Conference, Paris, March 2013
Gas Cooled Fast Reactors: Introduction
The GFR concept is: Very innovative: no demonstrator has ever been built
Challenging : high power densities of FRs and poor cooling capacities of gases
(The Helium coolant must be pressurized in normal operation to achieve
sensible in core gas velocities with reasonable pumping power)
Two major issues The design of a high temperature fuel element, able to retain integrity in case of loss of
forced cooling accident, to withstand high fast neutron fluxes, and offering good
neutronic performances,
Safety and decay heat removal in case of loss of helium pressure
Development roadmap the target commercial electricity generating reactor (~ 2400 MWth) and its fuel
a moderate power demonstrator, ALLEGRO (< 100 MWth) without electricity
generation as a necessary step towards an electricity generating prototype before
series production of commercial reactors : MOU signed by Hungary, Czech Republic,
Slovakia (2010) and Poland (2012)
| PAGE 5 C. Poette, CEA, FR13 Conference, Paris, March 2013
Gas Cooled Fast Reactors: Fuel element
A fuel based on high thermal conductivity and refractory materials:
Boundary accidental clad T° (DBA, 4th cat.): 1600°C/< a few hours
(FP confinement function, 1st barrier)
Ultimate accidental clad T° (SA prevent.): 2000°C/ < some min?,
(no loss of geometry, to keep the core cooling capacity)
Fuel element concepts : honeycomb plate and pin type
| PAGE 6 C. Poette, CEA, FR13 Conference, Paris, March 2013
Gas Cooled Fast Reactors: Fuel element
Although the plate type concept is attractive, fabrication difficulties
appeared which lead to focus first on the more classical pin
concept a ceramic matrix composite cladding comprising a sandwich of SiC cladding and a thin
internal metallic liner to ensure the leak tightness of the pin,
a “buffer” , porous carbon structure placed between the pellet and the cladding
allowing higher heat exchanges and moderate clad/pellet mechanical interaction.
| PAGE 7 C. Poette, CEA, FR13 Conference, Paris, March 2013
Gas Cooled Fast Reactors: Core design optimization
Main core characteristics Closed sub-assemblies (hexagonal wrapper tube)
Pin lengths limited to 1.50m (transport, handling, fabrication considerations): the total
fissile length is made of 2 half pins
Power : 2400 MWth , power density : 100 MW/m3 (to limit the Pu inventory)
Self-sustainable core (zero breeding gain)
Low core pressure drop (favoring natural circulation capacities) ~ 1.45 bar
Pu enrichment 16.3% at equilibrium
| PAGE 8 C. Poette, CEA, FR13 Conference, Paris, March 2013
Gas Cooled Fast Reactors: Core design optimization
Current core design
optimization process
Numerous iterations
FARM : a new tool
Coupling the different domains
to optimize both core performances
and safety characteristics
Optimisation
0,0
1,0
2,0
3,0
4,0
5,0
MSPu cycle
Diamètre cœur
MRPu
TsursisPuissance de pompage
Pint max
Moyenne acc non-
protégé
Mathieu
Référence
Illustration of core performance parameters and safety indicators for the “Mathieu” core vs the reference core
| PAGE 9 C. Poette, CEA, FR13 Conference, Paris, March 2013
Gas Cooled Fast Reactors: System design
Energy conversion and primary circuit arrangement Indirect combined cycle: He-Gas with a tertiary steam cycle Primary/secondary arrangement: 3 x 800 MWth (IHX-blower unit), gas turbo-
High efficiency (~ 45%) , compactness of the primary circuit, decoupling of
The Nuclear island from power conversion& heat applications
| PAGE 10 C. Poette, CEA, FR13 Conference, Paris, March 2013
Gas Cooled Fast Reactors: Safety aspects
Decay heat removal relying on gas circulation in the Primary circuit Using at first normal circuits operated in forced or natural circulation
Using dedicated DHR loops operated in forced or natural circulation
| PAGE 11 C. Poette, CEA, FR13 Conference, Paris, March 2013
Gas Cooled Fast Reactors: Safety aspects
Provisional conclusions
Encouraging potential of the reactor system (about 50 Initiating events + aggravating
events considered)
Design improvements are nevertheless recommended to cover some very
hypothetical situations like « loss of energy supply combined with failure of the primary
circuit reconfiguration »
RHP, blower (0.4-7 MPa)
axial mono stage,
Ptot < 500 KWe
Close containment
RHP, natural
convection capability
H1st + 2nd 20 m
RLP, blower (0.4-0.2MPa)
radial or axial technology
3 MWe
RHP, blower (0.4-7 MPa)
axial mono stage,
Ptot < 500 KWe
Close containment
RHP, natural
convection capability
H1st + 2nd 20 m
RLP, blower (0.4-0.2MPa)
radial or axial technology
3 MWe
Integration of primary
system and DHR
loops in the close
containment
| PAGE 12 C. Poette, CEA, FR13 Conference, Paris, March 2013
Gas Cooled Fast Reactors: Design improvements
Still various open innovative design options Reactor system design: Coupled cycle option (improved grace time in case of large LOCA,
less demanding in terms of backup pressure i.e potential suppression of the close
containment)
Principle scheme of the indirect coupled cycle: the primary circulator is
mechanically coupled to the secondary circuit turbo-machine
| PAGE 13 C. Poette, CEA, FR13 Conference, Paris, March 2013
Gas Cooled Fast Reactors: Design improvements
Still various open innovative design options DHR system design: the concept of autonomous Brayton cycle for DHR is promising;
it should be incorporated in the existing DHR architecture as an extra protection line in
the prevention of severe accidents.
Principle scheme of the autonomous DHR loop: the primary gas circulation
is ensured by a small turbo machine driven by the residual heat of the core
| PAGE 14 C. Poette, CEA, FR13 Conference, Paris, March 2013
Gas Cooled Fast Reactors: R&D program
Large R&D needs for the future
Fuel and core materials
The use of a ceramic material implies to adapt a specific codes & standards
approach, connected to appropriate tests and modelling,
The SiC behavior in accidental situations must be fully characterized,
Beyond the cladding, it is necessary to find solutions for the encapsulation of
the pins, these studies being at a very early stage ,
A program of irradiation of components and of qualification of fuel elements is,
of course, also necessary.
Helium technology Development of individual components and systems (fuel handling, thermal core
instrumentation, compressors able to work in large pressure ranges, valves,
check-valves, compact gas/gas heat exchangers, gas quality management,
thermal barriers ) use of existing Helium loops
demonstration that these components and systems are able to work together
especially for the safety demonstration. This requires large helium loops which
need to be constructed at mid term.
| PAGE 15 C. Poette, CEA, FR13 Conference, Paris, March 2013
Gas Cooled Fast Reactors: Conclusion
GFR : an attractive longer term option allowing to combine Fast spectrum & Helium coolant benefits
Innovative SiC fuel cladding solutions were found
A first design confirming the encouraging potential of the reactor system Design improvements are nevertheless recommended and interesting tracks have been identified (core & system design, DHR system)
The GFR requires large R&D needs to confirm its potential (fuel & core materials, specific Helium technology)
ALLEGRO prototype studies are the first step and are drawing the R&D priorities
