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Basic approaches in nuclear fission for applications
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Acronym: ABONA
Number / Date of the contract: 2-Cex06-10-79 / 01.08.2006
modul 1
Project Manager: Mihail Mirea
Partners: Bucarest University; Polytechnics University of Bucharest
Starting date / finishing date: 2006-08-01 / 2008-11-27
Project value: 1500000 RON
Abstract: The actual interest in developing the Th cycle for nuclear power plants is determined by social needs linked to security as to ensure the safety of nuclear power plants and to handle with responsibility the nuclear wastes. Although thorium itself cannot support a nuclear chain reaction, subjecting thorium to a barrage of neutrons inside a nuclear reactor convert this element to uranium 233, which can support fission. For this reasons, the design of nuclear plants have long time considered the possibility of combining thorium with a fissionable isotope, which would prime the reaction. For this purpose, a better modeling and experimental determination of cross-section evaluations were needed in the actinide and sub-actinide region. Actual evaluations are mainly phenomenological, the heights of the double fission barrier being determined empirically in accordance with a given parameterization of the nuclear level density. This procedure does not include the resonance due to the beta vibrational and rotational coupling adequately. Also, fission of actinides as well as sub-actinides is not yet understood sufficiently for increasing energies above a few MeV. Some efforts must be also involved in a better experimental determination of nuclear data by improving the experimental concepts and configurations. Fundamental research in the field of nuclear physics is necessary to improve our knowledge. The final goal is to obtain values of the neutron-induced cross sections within an accuracy of several percents while actually the error bars are of almost 30%. The actual project is involved in such efforts. It is intended to determine the dynamical and microscopic single-particle effects due to the second well barrier that can be quantified in the cross section. In this way, we expect to have a better modeling of neutron induced cross section resonance due to the second well and to the variation of the effective mass (supra-barrier resonance). It is also envisaged to improve the simulation for the capture cross section and formation of the compound nucleus. Effort is also done towards an accurate description of the sequence of processes induced in intermediate and relativistic energy nuclear reactions on targets envisaged to be used for Accelerator Driven Systems (ADS). Another goal is to envisage a new experimental set up for a better accuracy of nuclear data and to estimate the capture cross section. All these activities are focussed towards a better determination of nuclear properties of nuclei involved in the design of the new generation of reactors in order to provide more reliable data. These activities integrate themselves naturally in the field of fission for safe sources of energies and basic research.

THE STAGES OF THE PROJECT AND DELIVERY DATES
1. Matrix elements for generalized angular couplings (2006-12-15)
2. Improved two-center shell model (2007-02-25)
3. Primary fragments excitation energy and the average freeze-out volume in nuclear multi-fragmenta (2007-06-15)
4. Investigation of the 252Cf properties by taking into consideration the nuclear structure (2007-10-31)
5. Fine structure in the Th fission resonances (2008-02-25)
6. Measurements of the proton induce fission cross sections for Uranium (2008-06-30)
7. Dynamical model for fission of highly excited nuclei (2008-11-27)
RESULTS

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