Applied research at NICA in radiation materials sciences,
life sciences and new methods of energy production

Participating countries and international organizations:

Armenia, Belarus, Bulgaria, Mexico, Moldova, Russia, South Africa, Uzbekistan.

The problem under study and the main purpose of the research:

Obtaining applied research and technology results within the areas ARIADNA collaborations' activity, including life sciences, biomedical technologies, space research, radiation materials science, radiation hardeness of electronics, development of new technologies for ADS using NICA beams.

Brief annotation and scientific rationale:

The project is aimed to determine the optimum beam-converter combination meant to optimize the efficiency of an accelerator driven subcritical reactor. The planned research will be oriented in two directions. The first involves the comparative study of the fission distribution and the energy released in enriched fuel blanket, irradiated with proton beams with energy 0.2–2 GeV and ion beams with masses until ²⁰Ne and energies in the interval 0.2 – 1 AGeV. The second consists in measurements of the neutron yield from various converters, irradiated with proton and ion beams.

A possibility to realize a nuclear system with increased burning capabilities is to use an accelerator driven subcritical reactor (ADSR). It consists of a particle accelerator coupled with a nuclear reactor. The particle beam striking a converter placed in the central part of the reactor realizes a supplementary source of neutrons which allows the functioning of the reactor in subcritical regime (with criticality coefficient k_eff below 0.99), ensuring a safer exploitation of nuclear plants. The harder neutron spectrum obtained ensures a better incineration of the actinides.

In spite of the almost generalized opinion that the optimal beam for ADS is a proton beam with energy around 1–1.5 GeV we have shown in a series of works that ion beams have a superior energetic efficiency than protons. The activities within the project are oriented towards searching the conditions which maximize the energy efficiency of ADSR and ensure high burnup. Within the previous years, aspects related with the core geometry, the material used for the converter, the fuel composition, the working value of k_eff, the enrichment and power density distribution were investigated. The influence of the beam characteristics (particle type, energy, beam intensity), and of the accelerator type were also studied. The main conclusions obtained constitute the bases for extending the project in accordance with the stated objectives.

The proposed graphite target “GAMMA4” with fuel rods inserted inside and a central hole for the placement of different converters allows a correct comparison between the number of fissions and the energy released realized with proton and ion beams. The use of a graphite block instead of Pb gives the possibility to diminish the necessary amount of fissile material due to the softer neutron spectrum. Such target is easier to manipulate (due to its lower weight) and cheaper. The proposed graphite target “GAMMA4” is suitable for a comparative study of the efficiency of various beams in terms of the possibility of their use in ADS.

Expected results upon completion of the project: 

1. Selection of on an optimal design of a target of the ADS;

2. Verification of a principally new concept of a system based on the use of ion beams instead of protons;

3. Implementation of the first stage of experimental programme focused on measurement of neutron yields with different converter combinations.

Expected results of the project in the current year:

1. Determination of the optimal target design for the ADS.

2. Obtaining simulation results on the optimal design of the target for ADS.

 Collaboration