Grażyna Domańska

Fusion-driven transmutations of nuclear waste—a misconception or an incentive for promotion of fusion energy?

A fusion-driven system of transmutation of nuclear waste is presented. The main positive aspect of this fusion power option, thanks to energy release from fission, is the prospect of a radical reduction of necessary plasma energy gain, Q, to levels achievable in relatively simple mirror devices. Further advantages of the system include lower FW load and homogeneous heating distribution. The proposed application of the concept is as a fuel self-sufficient symbiont reactor co-operating with a number of serviced LWRs, for the regeneration of the spent fuel with incineration of external Pu. The doubling of burnup, i.e. halving the high level waste from symbiotic LWRs can easily slow down its build-up without any mechanical or chemical intervention in the fuel. In conclusion, the present option might facilitate the development and then launching of fusion power reactors.

Precise measurement of the integral cross section for the reaction 24Mg(n,p)24Na between 13.5 and 18.0 MeV

Abstract Activation technique has been used to measure the cross-section ratio for 24Mg(n,p)24Na and 27Al(n,a)24Na reactions, the last being a reference one. The reaction T(d,n)4 He was used to produce the neutrons. Countings of γ-spectra were performed with a 75 × 75-mm NaI (T1) detector. The new cross-section values for 24Mg were calculated based on the best values of the 27Al-reaction cross-sections for respective neutron energies. In general, the obtained total error is 1.5–2 times smaller than previously.

Assessment of the control rods shadow effect in the VENUS-F core

Abstract The partitioning and transmutation (P&T) of spent nuclear fuel is an important field of present development of nuclear energy technologies. One of the possible ways to carry out the P&T process is to use the accelerator driven systems (ADS). This technology has been developed within the EURATOM Framework Programmes for several years now. Current research in this field is carried out within the scope of 7th FP project FREYA. Important parts of the project are experiments performed in the GUINEVERE facility devoted to characterising the subcritical core kinetics and development of reactivity monitoring techniques. The present paper considers the effects of control rods use on the core reactivity. In order to carry out the evaluation of the experimental results, it is important to have detailed core characteristics at hand and to take into consideration the differences in the effect of control rods acting separately or together (the so-called shadow effect) on both the reactivity value and the measured neutron flux. Also any core asymmetry should be revealed. This goal was achieved by both MCNP simulations and the experimental results. However, in the case of experimental results, the need for calculating respective correction factors was unavoidable.

Modeling minor actinide multiple recycling in a lead-cooled fast reactor to demonstrate a fuel cycle without long-lived nuclear waste

Abstract The concept of closed nuclear fuel cycle seems to be the most promising options for the efficient usage of the nuclear energy resources. However, it can be implemented only in fast breeder reactors of the IVth generation, which are characterized by the fast neutron spectrum. The lead-cooled fast reactor (LFR) was defined and studied on the level of technical design in order to demonstrate its performance and reliability within the European collaboration on ELSY (European Lead-cooled System) and LEADER (Lead-cooled European Advanced Demonstration Reactor) projects. It has been demonstrated that LFR meets the requirements of the closed nuclear fuel cycle, where plutonium and minor actinides (MA) are recycled for reuse, thereby producing no MA waste. In this study, the most promising option was realized when entire Pu + MA material is fully recycled to produce a new batch of fuel without partitioning. This is the concept of a fuel cycle which asymptotically tends to the adiabatic equilibrium, where the concentrations of plutonium and MA at the beginning of the cycle are restored in the subsequent cycle in the combined process of fuel transmutation and cooling, removal of fission products (FPs), and admixture of depleted uranium. In this way, generation of nuclear waste containing radioactive plutonium and MA can be eliminated. The paper shows methodology applied to the LFR equilibrium fuel cycle assessment, which was developed for the Monte Carlo continuous energy burnup (MCB) code, equipped with enhanced modules for material processing and fuel handling. The numerical analysis of the reactor core concerns multiple recycling and recovery of long-lived nuclides and their influence on safety parameters. The paper also presents a general concept of the novel IVth generation breeder reactor with equilibrium fuel and its future role in the management of MA.

Measurement of cross-section for 24Na production from magnesium isotopes by 13.5–18.0 MeV neutrons

Abstract Activation technique has been used to measure cross-sections for 25Mg(n,np + d + pn)24Na and to evaluate their upper limits for 26Mg(n,2np + npn + nd + t + dn + p2n)24Na reactions, respectively. The 27Al(n,α)24Na reaction has been used as reference. The obtained results allowed for correction of the previously determined cross sections for 24Mg(n,p)24Na reaction.