Comparative of blanket reactor design in assuring of tritium self-sufficiency

The comparison of four blanket modules in DEMO made up the optimization material having a reasonable requirement as blanket material in this study. Either neutron flux distribution in blanket material or material endurance under neutron irradiation, from four modules, the WCLL has a high tolerance neutron distribution and the best neutron irradiation endurance. Furthermore, many suggestions closed to the statement to use the benefits of water coolant and lithium lead (compose Li-6) as a material component in the blanket.

Position evaluation of ex-core neutron flux measurement in new type graphite reactors

Several concepts of new reactors use graphite. Some of them use graphite as a moderator, some of them as a reflector. There are at least two concepts of these graphitetype reactors under development in the Czech Republic. Both reactors use graphite as the reflector. An in-core measurement might be impossible to use because of various reasons, for instance, high temperature or aggressive environment. Therefore, this article focuses on ex-core neutron flux measurement system placed in the graphite reflector and the optimization of ex-core detector position. A set of experiments were performed at LR-0 reactor. The LR-0 is a light water reactor with a well-defined neutron field, which can be used for different material insertion tests and testing of its influence on criticality. Several modifications of LR-0 cores were modelled in Monte Carlo codes Serpent and KENO. A set of calculations were performed for verification of the criticality and neutron flux course in the reactor core and graphite reflector. Further investigation was focused on the influence of the presence of a graphite reflector on the neutron distribution in the reactor core. The LR-0 graphite experiments were also used to verify the calculations. Based on the results of this article, the optimal position of ex-core detectors in the graphite reflector is proposed.

Angular Distribution of Neutrons Around Thick Beryllium Target of Accelerator-Based 9Be(d, n) Neutron Source

An experimental work and simulations were carried out to determine the angular distributions of neutrons and yields of the 9Be(d, n) reaction over all angular range (360 deg) on a thick beryllium target as an accelerator-based neutron source at incident-deuteron energy 13.6 MeV. The neutron activation method was used in the experimental part using aluminum and iron foils as detectors to calculate the neutron flux. The Monte Carlo neutral-particles code (MCNP5) was used to demonstrate and simulate the neutron distribution, also to understand and compare with the experimental results. The neutron energy spectrum was computed using the projection angular-momentum coupled evaporation code PACE4 (LISE++) and the spectrum was adopted in MCNP5 code. Two experimental ways were used, one with beryllium target and another one without the beryllium target, to evaluate the neutron flux emitted only by the beryllium target. Typical computational results were presented and are compared with the previous experimental data to evaluate the computing model as well as the characteristics of emitted neutrons produced by the 9Be(d, n) reaction with a thick Be-target. Moreover, the results can be used to optimize the shielding and collimating system for neutron therapy.

Development of MC-based uncertainty estimation technique of unfolded neutron spectrum by multiple-foil activation method

Unfolding process plays an important role in neutron energy distribution measurement by means of the multiple-foil activation method. We have developed an algorithm for estimating uncertainty of resultant neutron distribution. For the demonstration of the algorithm, we have conducted an experiment to measure thick-target neutron yield (TTNY) of the C(d,n) reaction induced by 20-MeV deuterons with the multiple-foil activation method. The experiment was conducted at Cyclotron and Radioisotope Center, Tohoku University in Japan. The obtained experimental data were analyzed by the algorithm. As a result, we found that uncertainty of derived TTNY has dependency on neutron emission energy. In addition, the dependency is caused by excitation functions of activation reactions. Therefore, we found the particular reactions causing large uncertainty in TTNY. The result of present study shows that the algorithm can evaluate uncertainty and its causes.