RADIOLOGICAL HAZARD ASSESSMENT FOR THE BEAM DUMP OF HIGH INTENSITY DEUTERON ACCELERATORS D. López 1, 2,* , M. García 1, 2 , J. Sanz 1, 2 , F. Ogando 1, 2 , P. Sauvan 1, 2 , A. Mayoral 2 1 Instituto de Fusión Nuclear, UPM, 2 Dpto. de Ingeniería Energética, UNED, Madrid, Spain Abstract The Engineering Validation and Engineering Design Activities (EVEDA) phase accelerator prototype of the International Fusion Materials Irradiation Facility (IFMIF) project will require a Beam Dump (BD). Low activation and low neutron production are some desirable properties that beam facing stopping material (BFSM) should possess. In order to compare the behaviour of candidate materials in a preliminary design of BFSM, Aluminium, Copper, Nickel and Tungsten are studied according to neutron production, generation of troublesome isotopes of concern for gamma dose rates evaluations and its final management options as radioactive waste. A relevant objective in this process is the identification of the main reactions on neutron production and activation behaviour, which can be helpful for further improvements of deuteron cross section. INTRODUCTION The irradiation scenario expected in the EVEDA BD is 125 mA current of charged particles with 9 MeV energy. Charged particles are deuterons (D + ) for normal operation. The BFSM (preliminary design considered is a cone of inner dimension: 20 cm diameter, 250 cm length and 0.3 cm thickness) will be activated by both primary charged particles and secondary generated neutrons. These neutrons are also responsible of activation in other components of the BD due to its high penetration. Flux level considered for D + induced activation is 10 15 d/cm 2 s, which is obtained considering the geometry mentioned above. Neutron induced activation is calculated using the flux obtained multiplying deuteron flux by the corresponding neutron per deuteron value evaluated for each material in the next section. In the activation assessment, ACAB code [1] was used considering 1 month of continuous irradiation. For the candidate materials, neutron production per incident deuteron is computed and reactions resulting on troublesome isotopes in gamma dose rates evaluations are identified. Also, unconditional clearance and near surface disposal as radioactive waste management options are discussed. NEUTRON PRODUCTION In the evaluation of neutron produced by incident deuteron only the contribution coming from d-material reactions has been considered. Three methods for this computation have been used: MCNPX [2] and PHITS [3] transport codes and an own procedure [4] that, after characterization of deuteron flux, uses neutron production cross section obtained by EAF-2007 deuteron data library [5] processing. Results are shown in Figure 1, noting significant differences in the case of Tungsten. These differences between methods can be attributed to two causes: the first one are the nuclear models contained in each transport code, and the other one is the fact that MCNPX transport code do not produce secondary neutrons up to 6 MeV approximately. This last aspect is the reason why PHITS and the own procedure were employed. This last method was also used in the neutron flux computation in order to take into account recent nuclear data contained in EAF-2007 library. 1.E-06 1.E-05 1.E-04 1.E-03 Al Ni Cu W n/d MCNPX PHITS EAF DATA Figure 1: Neutrons produced per 9 MeV incident D + . The most important reactions contributing to neutron production up to 9 MeV deuteron energy are given in Table 1 for the natural isotopes of the candidate materials. Table 1: Reactions contributing to neutron production Natural Isotopes Reaction Al27 (100%) (d,n), (d,na) (d,n), (d,2n), (d,na) Cu63 (69.17%) Cu65 (30.83%) (d,n), (d,2n), (d,na) (d,n) (d,n) (d,n), (d,2n) (d,n), (d,2n) Ni58 (68.077%) Ni60 (26.223%) Ni61 (1.14%) Ni62 (3.634%) Ni64 (0.926%) (d,n), (d,2n) (d,n), (d,2n) (d,n), (d,2n), (d,2n)-m (d,n), (d,2n), (d,n)-m (d,n), (d,2n), (d,2n)-m W180 (0.12%) W182 (26.5%) W183 (14.31%) W184 (30.64%) W186 (28.43%) (d,n), (d,2n), (d,2n)-m * dalogomu@bec.uned.es MOPD026 Proceedings of EPAC08, Genoa, Italy 06 Instrumentation, Controls, Feedback & Operational Aspects 502 T18 Radiation Monitoring and Safety