PhD thesis

Development and Evaluation of Analytic Solutions for the Improved Analysis of Accelerator-Driven System Experiments

PhD student:
Varvara Glivici-Cotruță
Dr. Bruno Merk (HZDR)
Reactor Safety


Around 2,600 tonnes of spent nuclear fuel per year are generated in European Union. As a result, the problem of radiotoxicity and a save long-term disposal of the irradiated nuclear fuel has to be solved. In recent years, the accelerator-driven subcritical reactors (ADSR or ADS) were proposed for the transmutation of the transuranic elements from spent nuclear fuel. ADS can be also used for the energy production from the abundant element thorium. An operation of ADS requires reliable online reactivity determination methods. The classical methods for reactivity calculation (Sjöstrand method and Slope fit method) have shown an inaccuracy, when applied to subcritical configurations in the experimental campaigns (YALINA, MUSE). New methods for the analysis are needed.


To improve our knowledge of neutron space and time behavior in a subcritical medium, in Helmholtz-Zentrum Dresden-Rossendorf it was proposed to develop solutions for the space and time dependent diffusion and Telegrapher’s equations analytically without separation of space and time. The reflective boundary and zero initial conditions in one-dimensional slab were used. The Green’s function method was applied. The derived solutions were compared with experimental data in the fast area from the YALINA-Booster experiment. As a further development the time-dependent, one-dimensional diffusion equation is solved for a finite slab of two layers.