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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.1 Presentation title – Presenter/ref. - 02 July 2013 - p.1
Engineering and Projects
ICAN Conference Accelerator-Driven Sub-critical Reactors
B. CARLUEC
CERN, June 28, 2013
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.3
Content
History and motivations
The nuclear wastes
The transmutation scenarios
The ADS concept
MYRRHA
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.4
History and motivations
1940 – 1993
Since 1940’s it is known that the proton bombardment of
an uranium target generates neutrons
En 1941, G. Seaborg created the first plutonium in this way
During the 1950’s and 60’s, many programs were
developed for producing fissile materials with this
mechanism (uranium and thorium targets producing 239Pu
and 233U)
At the end of 1980’s, the “Accelerator Driven System”
concept born in the USA with transmutation of nuclear
wastes as a possible application
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.5
History and motivations
1993 - 2000
In 1993, C. Rubbia at the CERN created the “Energy
Amplifier” concept; the goal was to produce electrical
power with an ADS
2000, in France
The Law (December 30, 1991) related to the nuclear waste
management required to assess this issue following three
aspects: geological disposal, temporary storage,
transmutation)
The definitive shutdown of the fast reactor Superphénix in
1997 led to reassess the transmutation capabilities with a
dedicated facility: the ADS
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.6
History and motivations
Production of fissile material:
No needs currently
Fast breeder reactors have been demonstrated
to be efficient
Energy production:
Economically prohibitive compared to critical reactors, in
particular because of the power required for the proton
accelerator operation
Other technically and economical issues have to be
resolved
Transmutation of nuclear wastes
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.7
The nuclear wastes
Half-life (years) Radiotoxicity (Sv/TWhe)
1 000 years 10 000 years 100 000 years
Total LWR at
33GWd/t
3,10 108 7,70 107 4,20 106
Minor actinides
Np 2 140 000 5,46 104
Am 7 380 2,85 107 1,93 106 1,13 105
Cm 8 500 9,30 105 3,08 105
Long life FP 1,86 103 1,85 103 1,34 103
79Se 65 000 1,12 102 9,24 101 4,03 101
93Zr 1 500 000 2,23 102 2,22 102 1,88 102 99Tc 210 000 6,70 102 6,84 102 4,84 102
126Sn 100 000 4,46 102 4,44 102 2,28 102
129I 15 700 000 2,98 102 2,96 102 2,96 102 135Cs 2 000 000 1,12 102 1,11 102 1,08 102
Mining wastes 7,20 105 6,60 105 2,60 105
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.8
The nuclear wastes Minor actinides LWR fuel decreasing during 15 years
Isotope Amount (g/tonne) 236Np 5,3 10-4
237Np 6,5 10+2
238Pu 2,3 10+2
239Pu 5,9 10+3
240Pu 2,6 10+3
241Pu 6,8 10+2
242Pu 6,0 10+2
244Pu 4,2 10+2
241Am 7,7 10+2
242mAm 2,5 10+0
243Am 1,4 10+2
242Cm 5,9 10-3
243Cm 4,3 10-1
244Cm 3,1 10+1
245Cm 2,3 10+0
246Cm 3,2 10-1
247Cm 3,7 10-3
248Cm 2,4 10-4
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.9
The nuclear wastes
Actinides are fissile material
Their transmutation is efficient only if:
The fission probability is higher than the capture
probability
Neutrons are available for fission of actinides
These characteristics can be got with a fast
neutron spectrum
The transmutation also must limit the
production of additional nuclear wastes
Minimization of breeding material
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.10
The nuclear wastes
Introduction of minor actinides inside the core of a nuclear reactor leads to:
A reduction of the fraction of delayed neutrons (this is necessary for the stability of critical reactors)
A low Doppler coefficient (which create a negative feedback effect)
The introduction of significant amount of minor actinides cannot be done in a critical reactor for safety
reasons
The sub-critical reactors (ADS) are a solution
The transmutation of FP might be performed, but this is relevant only for certain isotopes and would require isotopic separation
This option is no more considered
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.11
The transmutation scenarios
Many scenarios can be considered for nuclear
waste management (minor actinides) with
ADS
“Double strata” scenarios
First stratum by LWR burning UOX or MOX fuels
Second stratum with ADS burning the MA
produced by LWR
Depending on the amount of Pu used in the first
stratum, the amount of ADS needed is between 15
and 21% of the total power (equilibrium state)
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.12
The ADS concept
Three main parts:
A particle accelerator
Usually the particles are protons
A neutron source (spallation
target)
The target produces neutrons,
depending on the amount of
protons and their energy, and the
spallation material
A sub-critical core
Minor actinides are in the core, in
a fast neutron spectrum
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.13
The ADS concept
Key numbers
Core power: for economical reasons, the sub-critical core power
should be in the range: 100 – 1000 MW
Sub-critical level: for safety reasons, the sub-criticality should be
able to compensate any reactivity insertion in accident
conditions; the sub-critical level should be in the range:
3000 – 5000 pcm (Keff= 0.97 – 0.95)
The fission energy is about 200 MeV (= 3.3 10-11 J)
The neutron source should be: 1017 – 1018 n/s
The spallation efficiency is about:
30 neutrons per proton of 1 GeV
The proton beam current should be: 0.5 – 8 mA
The beam power should be: 0.5 – 8 MW
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.14
The ADS concept
The accelerator
For a spallation target using lead, the optimum amount of neutrons is got with
protons having around 1 GeV (30 neutrons per proton)
A LINAC has to be considered
The spallation target
The spallation target has to use heavy metal which gives a maximum amount of
neutrons
The spallation target has to be cooled for removing the heat generated by the
spallation mechanism (liquid target)
The spallation target has to be located inside the core
The spallation target has to be separated from the accelerator (physical barrier –
window- or not)
The sub-critical core
Fast neutron spectrum
The core has to be cooled by a coolant which does not slow down the neutrons
(liquid metal or gas)
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.15
The ADS concept
The main challenges for the accelerator
To be capable to produce a reliable proton current: very
significant decreasing of the number of beam losses existing in
the LINAC used for fundamental physics research
Reliable control of the accelerator: similar to the control
systems of critical reactors
Limitation of the proton losses (radioprotection)
To maintain a sufficient core containment
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.16
The ADS concept
The main challenges for the spallation target
Reliable coolability, especially of the window
Window behavior in proton beam conditions
Containment of the spallation products
The main challenges for the core
Same issues than the ones of a critical fast reactor
Control of the reactor
Monitoring of the sub-criticality
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.17
The ADS concept
Control of a critical reactor:
iiii
ii
Cl
N
dt
dC
CNldt
dN
Control of a sub-critical reactor:
SN
In a critical reactor
The power of the core is defined by the capability to remove this power (stabilization
by the neutronic feedbacks)
The introduction of absorber shuts down the nuclear reactions
In a sub-critical reactor
The power is defined by the neutron source (low impact of the neutronic feedbacks)
The introduction of absorber has a limited impact
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.18
MYRRHA
Courtesy H. Aït Abderrahim
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.19
MYRRHA
Courtesy H. Aït Abderrahim
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.20
MYRRHA
Courtesy H. Aït Abderrahim
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.21
MYRRHA
Courtesy H. Aït Abderrahim
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.22
MYRRHA
Courtesy H. Aït Abderrahim
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ICAN Conference - ADS Reactors
B. Carluec. – June 28, 2013 - p.23
The MYRRHA accelerator
Courtesy H. Aït Abderrahim