Activation analysis and evaluation of the radionuclide inventories, decay heat for European DEMO divertor components.

This work presents neutron flux calculation results and specific decay heat and activity for the European DEMO reactor divertor structure. Two DEMO 2017 models were used in calculations; one with a homogenised WCLL breeder blanket and the other with a homogenised HCPB breeder blanket. The neutron flux calculations were performed using MCNP6 code with JEFF 3.2 nuclear data. Activation and decay heat calculations were performed using the FISPACT-II code with TENDL - 2017 nuclear data library.

Dose rates and specific activities of Li2CO3 pellets and diamond detectors irradiated during TT and DTE2 campaigns at JET.

TT and DTE2 campaigns at JET are expected to produce large 14 MeV neutron fluxes that will enable the expansion of activation detection ranges. The calculation results of the activation and dose rates induced in Li2CO3 pellets and diamond detector materials are presented in this research. The MCNP code was used in order to produce corresponding neutron flux densities and spectra. The FISPACT code with the EAF-2010 library was used to estimate the activation and dose rates.

Neutronic analysis of IFMIF-DONES test cell cooling system.

IFMIF-DONES (International Fusion Materials Irradiation Facility - DEMO-Oriented Neutron Source) is an accelerator based d-Li neutron source currently under development within the framework of EUROfusion Power Plant and Technology (PPPT) programme. The purpose of the IFMIF-DONES device is to qualify promising materials for the future fusion technologies. The neutron source is designed to produce high energy neutron emission comparable to large scale nuclear fusion reactors running with deuterium and tritium fuel. Test Cell (TC) is a section of accelerator facility where material specimens are being irradiated. Neutron irradiation affects not only specimens, but also supporting structures and confinement that include steel liner and the water-cooled concrete walls. The neutron induced activation and subsequent decay heat generation of the cooling pipes needs to be assessed for the maintenance, decommissioning and waste management purposes and related safety analyses. This paper presents the analyses performed within the ENS (Early Neutron Source) project of EUROfusion/PPPT with an aim to provide up-to-date estimates of the activity inventories and the decay heat generation in the DONES TC facility shielding wall and pipes. A series of coupled MCNP particle transport and FISPACT inventory calculations were performed using the 2017 DONES TC model and nuclear cross-section data from the JEFF-3.1.2 data library. The paper discusses activation characteristics propagated by neutron irradiation in the biological shielding cooling system. Activities, decay heat, dose rates are presented as function of the decay time after irradiation.

Activation Inventories after Exposure to DD/DT Neutrons in Safety Analysis of Nuclear Fusion Installations.

Irradiations with 14 MeV fusion neutrons are planned at Joint European Torus (JET) in DT operations with the objective to validate the calculation of the activation of structural materials in functional materials expected in ITER and fusion plants. This study describes the activation and dose rate calculations performed for materials irradiated throughout the DT plasma operation during which the samples of real fusion materials are exposed to 14 MeV neutrons inside the JET vacuum vessel. Preparatory activities are in progress during the current DD operations with dosimetry foils to measure the local neutron fluence and spectrum at the sample irradiation position. The materials included those used in the manufacturing of the main in-vessel components, such as ITER-grade W, Be, CuCrZr, 316 L(N) and the functional materials used in diagnostics and heating systems. The neutron-induced activities and dose rates at shutdown were calculated by the FISPACT code, using the neutron fluxes and spectra that were provided by the preceding MCNP neutron transport calculations.

Assessment and benchmarking of the impact to gamma dose rate employing different photon-to-dose conversion factors using MCNPX code at the decommissioning stage of Ignalina Nuclear Power Plant.

A comparative study was performed to reveal the impact of several photon-to-dose conversion factors for gamma dose rate calculations when applied to heterogeneous environment in the case of decommission stage of the Ignalina Nuclear Power Plant. The following set of conversion factors were investigated by employing the Monte Carlo N-particle transport (MCNPX) code derived from the recommendations given in ICRP-21, ICRP-74 and ANSI/ANS-6.1.1 standards (1977 and 1991), based on the experiments performed for gamma radiation dose rate measurements inside the deplanting Emergency Core Cooling System tank. MCNPX precise simulation and the benchmark between the conversion coefficients highlighted the impact to the results for the selected case of this investigation. The results revealed that the data from the ANSI/ANS-6.1.1 1991 publication are reliable for various dose and shielding calculations in the case of decontamination of radioactive equipment and similar applications since it showed a statistically satisfied agreement between the simulation results and experimental data. These tendencies suggest that the radiological protection system currently adopted in NPP during the decommissioning stage can be characterised using ANSI/ANS-6.1.1 1991 standards with respect to gamma dosimetry.