Impact of corrosion products on the IFMIF Lithium loop activation induced by neutrons: inventories, gamma decay sources and dose rate estimations

The Report presents a first assessment of the impact of corrosion products produced in IFMIF lithium loop from the perspective of worker doses. Activation of the impurities contained in liquid lithium occurs during the passage through the target both due to irradiation of neutrons and of the deuteron beam. Only the impact due to neutron activation, produced in the d+Li interactions, has been considered in this Report. Contact dose rates, as a measure of the biological potential hazard of the total decay gamma-ray source, as a direct contact, of the activated material, have been evaluated via the ANITA-IEAF activation code package. The dose rates due to the transport of decay gamma rays on the surfaces and at 50 cm, 1m and 5m of main lithium loop components, Longest Pipe, Heat Exchanger and Quench Tank, have been estimated at shutdown and at different cooling times. These calculations were performed via the deterministic Vitenea-IEF/SCALENEA-1 shielding sequence and MCNP-4C2 code, as a check. Main conclusions of these first calculations are: - the worker radiation protection could be a concern for IFMIF if a good purification system of Li will not continuously run, - all Li loop area have to be declared “Restricted Access Zone” and, - specific procedures and worker protection equipments (such as Remote Handling tools) and shielding have to be considered to maintain the Li loop. Future work have to be dedicated to perform further parametric evaluations varying main input data, such as corrosion rates and irradiation scenarios, and to evaluate effects of deuteron beam.