Technical issues and requirements of experiments and facilities for fusion nuclear technology

Abstract

The technical issues, development problems and required experiments and facilities for fusion nuclear technology have been investigated. The results have been used to develop a technical framework for a test plan that identifies the role, timing, characteristics and costs of major experiments and facilities. A major feature of this framework is the utilization of non-fusion facilities over the next 15 years, followed by testing in fusion devices beyond about the year 2000. Basic, separate effect and multiple interaction experiments in non-fusion facilities will provide property data, explore phenomena and provide input to theory and analytic modelling. Experiments in fusion facilities can proceed in two phases: (1) concept verification and (2) component reliability growth. Integrated testing imposes certain requirements on fusion testing device parameters; these requirements have been quantified. The nuclear subsystems addressed in the study are: (a) blanket and first wall; (b) tritium processing system; (c) plasma interactive components; and (d) radiation shield. The two generic classes of liquid and solid breeder blankets have significant engineering feasibility issues, and new experimental data must be obtained before selection of an attractive design concept. Liquid metal blanket issues are dominated by problems related to momentum, heat and mass transfer, which can be addressed in non-neutron test facilities. Solid breeder blanket issues are, however, dominated by the effects of radiation, including heating, transmutation and damage, which can be reasonably addressed in fission reactors. The tritium processing uncertainties are primarily related to the control and recovery systems, and most can be addressed in existing and planned non-neutron facilities. A dominant feature of plasma interactive components is the strong interrelation to both plasma physics and nuclear technology. Required facilities include thermomechanical test stands and confinement devices with sufficiently long plasma burn. The radiation shield poses no feasibility issues, but improved accuracy of predictions will reduce design conservatism and lower costs.

Blanket/first wall challenges and required R&D on the pathway to DEMO

“…However, nuclear transmutations in the fusion neutron environment produce significantly higher concentrations of solid elements which have the potential to modify the electronic properties of SiC since it is an impurity semiconductor. Recent calculations for the production rates of potentially deleterious elements are Mg (10-45), Be (5-18), Al (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14), and P (0.2-1.5) appm/dpa [125]. The impact of the solid transmutant population on electrical conductivity in a neutron irradiation environment is presently unknown and thus constitutes a significant feasibility issue.…”

“…The classification is in analogy with other technologies and was used extensively in technically-based planning studies, e.g. FINESSE [4][5][6]. Such classification is almost always used in external high-level review panels of new technology development.…”

“…Also shown for each stage, is the size for test articles and the total testing area at the first wall to perform the required experiments. All these requirements in Table 10 were derived from detailed studies [5,6,10,11] that investigated the issues, the required experiments and developed and applied engineering scaling laws to enable extrapolation of the results from experiments to future DEMO and power reactors.…”

“…Early in the 1980s, it was recognized in the US that the FNST, particularly the blanket is complex and its development requires detailed investigation. The US carried out a pioneering study called FINESSE 2 [4][5][6][7][8][9][10][11][12]. This was a major study which identified and characterized the issues, and the requirements for experiments and non-fusion and fusion facilities for all FNST.…”

The Mission and Technology of a Gas Dynamic Trap Neutron Source for Fusion Material and Component Testing and Qualification

“…For each breeding blanket material system, there is a set of tests ranging from property measurements to component verification. The test categories adopted in previous studies 31,32 and illustrated in Figure 2 are: basic, single effect, multiple effect/multiple interaction, partially integrated, integrated, and component tests. Specimens, elements, and submodules can be used to address basic, single effect, and multiple effect/multiple interaction issues.…”