The report discuss research activities objected to nuclear reactivity accidents and examines a program for increasing nuclear safety.
Destructive test results are described to afford an general concept of reactivity accidents. The SPERT-CDC experiments are cited as a new form of research program to gain a more detailed and clear insight into the accident behavior. The relaionship between excursion power, fuel rupture and destructive energy is also discussed.
Attenion is drawn to the increasing importance of reactivity accident analyses for advanced type reactors, such as large light water power reactors. The report presents reactivity accident programs by pulse reactors such as CDC, PBF, TREAT and NSRR (Japan). Finally an outline of the NSRR program is given.