Activities in the field of nuclear transmutations in Poland

The objective of the study was Validation of an universal neutronic computing total the MCNP code, for studies of subcritical kinetics. Better understanding of the routine results provided by the code, thus, its proper use Seek for adequate ways of reactivity measurement (in particular - noise methods). In an accelerator-driven subcritical system ADS subcritical assembly in Dubna. In search of the internal consistence of the MCNP code it has been demonstrated that for bare systems the slope of prompt neutrons decay has agreed with the parameters of neutron multiplication: k (prompt) and fission lifespan as the generation time. In case of reflected systems the zone adjacent to the subcritical core /reflector + shield/ proved to be a neutron storage, i.e. a second 'source' determining the behaviour of neutron field. The observed parameters of the neutron field decay as affected by this region do not reflect properties of the multiplication chain alone. The option of water cooled research assembly deserves consideration whereas the effective decoupling as not achieved yet, it requires further investigations. The test of application of the Feynman-a method for the analysis of kinetics of reflected subcritical systems has proved the independence of the core surrounding, but its sensitivity to the detection efficiency and the detector dead time may be a problem. Reliable knowledge of these parameters is required In addition to this, a direct comparison of the calculations with the respective experiment seems hardly possible in view of excessive computation times. Further pertinent studies including the application of the third moment of the reactivity measurements are foreseen