ican conference - ads reactors presentation title

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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




B. Carluec. – June 28, 2013 - p.3

Content

History and motivations

The nuclear wastes

The transmutation scenarios

The ADS concept

MYRRHA




B. Carluec. – June 28, 2013 - p.4


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




B. Carluec. – June 28, 2013 - p.5


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




B. Carluec. – June 28, 2013 - p.6


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




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




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




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




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




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)




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




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




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)




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




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




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




B. Carluec. – June 28, 2013 - p.18

MYRRHA

Courtesy H. Aït Abderrahim




B. Carluec. – June 28, 2013 - p.19

MYRRHA





B. Carluec. – June 28, 2013 - p.20

MYRRHA





B. Carluec. – June 28, 2013 - p.21

MYRRHA





B. Carluec. – June 28, 2013 - p.22

MYRRHA





B. Carluec. – June 28, 2013 - p.23

The MYRRHA accelerator





B. Carluec. – June 28, 2013 - p.24

Thank you for your attention

ican conference - ads reactors presentation title

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