Accelerator Driven Subcritical Reactors Cristian Bungau Manchester University
Accelerator Driven Subcritical Reactors Cristian Bungau Manchester University December 2007
ADSR Purpose 1. Nuclear energy concerns –> radioactive waste management. ADSRs can help in the transmutation of minor actinides (Np, Am, Cm, …) and long lived fission products. 2. ADSRs are an alternative concept to the critical nuclear reactor. Main advantage -> non-critical fission core. Fission chain sustained by a neutron source placed at the centre of the core. Neutrons are emitted via spallation of heavy nuclei under a heavy energy proton beam generated by a suitable particle accelerator. • inherent safety: the reactor is switched off at the moment the proton beam is switched off.
ADSR Accelerator Driven Subcritical Reactor charged particle target for generating neutron accelerator subcritical reactor Beam off chain reaction stops Safer system !
Issues in the choice of the basic accelerator concept 1. Proton beam energy: 350 Me. V – 1 Ge. V. 2. Proton beam intensity: 20 – 50 m. A. 3. Number of allowable beam trips: 5/year, not longer than 1 s ! • Number of allowable beam trips -> frequently repeated, they can significantly damage the reactor structures, the target or the fuel, and also decrease the plant availability. • Proton beam current intensity -> Up to now, only sector-focused cyclotrons and linacs are able to provide beam currents in the m. A domain. • There is also possible to use ns. FFAG synchrotrons. Advantage -> more electrical power efficiency. 1. The 600 Me. V cyclotron of PSI delivers about 2 m. A on a routine basis. However, reaching up to 20 m. A is more questionable, and might require two cyclotrons with the beams being funneled together. 2. The industrial transmuter needs an ~1 Ge. V proton beam, and a cyclotron reaches its intrinsic limit because the proton is becoming too relativistic. 3. None of these limitations are present in a linac which can reach 100 m. A intensities without any intrinsic energy limit.
MYRRHA – ADSR project (Belgium)
KURRI – ADSR project (Japan) 100 ke. V 2. 5 Me. V 20 Me. V 150 Me. V ion source subcritical reactor injector booster main ring Beam intensity -> 100 n. A – 1 µA; 1 Ge. V proton beam Future development -> additional FFAG synchrotron 100 µA beam intensity
Future Work • Compare different accelerator models to choose the basic accelerator concept. • Decide whether to concentrate on U or Th fuelled reactors. • Decide weather to concentrate on power generation or waste disposal.
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