Fission release characteristics from fuel

The spent fuel elements from a fission reactor are much more intensely radioactive than the original fuel elements, (a) What does this teU you about the products of the fission process in relationship to the belt of stability. Figure 21.2 (b) Given that only two or three neutrons are released per fission event and knowing that the nucleus undergoing fission has a neutron-to-proton ratio characteristic of a heavy nucleus, what sorts of decay would you ejqject to be dominant among the fission products ... 

A characteristic safety feature of the HTR-Module is to be found in the fact that, in all operating and accident situations, the radioactive materials formed during nuclear fission are enclosed in the coated particles in such a way that a significant activity release from the coated particles can be excluded. This safe activity enclosure is guaranteed by the design of the fuel particle coatings and the inherent limitation of the maximum possible accident temperature of the fuel elements to approx. 1600 C. 

Gas-cooled reactors also have good ATWS characteristics without any alternative action. But the power rating and the core dimensions are hmited so as not to release fission gas from the coated particle fuels at accidents. On the other hand, the good ATWS characteristics of the Super LWR are achieved with a high core power rating. Therefore, it is an advantage in the reactor design. 

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