In this work we investigate the influence of sub-criticality on the safety of molten salt reactors. A direct comparison between critical and sub-critical systems is done by simulating a number of unprotected transients. For this purpose different levels of sub-criticality are tried to improve system’s safety and, at the same time, to define the intensity of the external neutron source. It is shown that a considerable expansion of the time interval of core vitality can be achieved even if a very low sub-criticality level (350-700 pcm) is applied. Consequently, the requirements for the external neutron source intensity are considerably decreased when compared to deeply sub-critical systems. In this context, the use of an electron accelerator instead of proton machine is investigated in detail including economical, physical and technical realization constraints. |
