Vladimir Artisyuk

Transmutation of Zirconium-93 in High-flux Blanket of Fusion Neutron Source

Amongst fission products discharged from a fission reactor, mainly iodine and technetium are considered as of primary concern. Their transmutation has been of high priority to reduce the long-term consequences of nuclear energy generation. So far little attention was given to radioactive 93Zr, but its hazard appears to be rather substantial. The importance of 93Zr transmutation is emphasized in the present paper. It is demonstrated that the fusion driven neutron source with high-flux blanket can be applied to transmute 93Zr sufficiently and resolve the problem of its accumulation within the time period of several decades.

Advanced U–Np–Pu fuel to achieve long-life core in heavy water reactor

The objective of this paper is to look at the possibility of approaching the long-life core comparable with reactor life-time. The main issues are centered on U–Np–Pu fuel in a tight lattice design with heavy water as a coolant. It is found that in a hard neutron spectrum thus obtained, a large fraction of 238Pu produced by neutron capture in 237Np not only protects plutonium against uncontrolled proliferation, but substantially contributes in keeping criticality due to improved fissile properties (its capture-to-fission ratio drops below unit). Equilibrium fuel composition demonstrates excellent conversion properties that yield the burn-up value as high as 200 GWd/t at extremely small reactivity swings.

Long-life water cooled small reactor with U-Np-Pu fuel

The paper presents the advanced concept of a long-life small light water reactor in which the fuel irradiation time is comparable with reactor life-time. The equilibrium analysis reveals that the U-Np-Pu fuel with unique neutronic properties allows to keep sufficient criticality up to burnup value about 140GWd/tHM. The fuel recycle does not lead to additional Pu accumulation. Both Pu and Np are well protected against un-controlled proliferation by a large fraction of 238Pu in their mixture. To improve the reactor safety, the wider fuel pin lattice was applied. The radiation damage of structural materials is within the stainless steel limitation.

Transmutation of Elemental Cesium by a Fusion Neutron Source

Abstract Transmutation of radioactive Cs from fission products of nuclear reactors without the potentially dangerous and expensive operation of isotopic separation is addressed. Transmutation is proposed to be performed in the blanket of a fusion neutron source with the plasma performance characteristics inherent in the current research on fusion reactors. The domain of Cs transmutation is quantitatively determined with detailed neutronics analysis of hard and softened neutron spectra, the effect of first wall loading, and two reprocessing modes. One is continuous on-line reprocessing; another one deals with a multicycle option in which a substantially long irradiation period is assumed before reprocessing. Transmutation efficiency is estimated in terms of the effective lifetime of 135Cs, which is the key characteristic governing the approach to equilibrium and the fraction of power associated with cesium transmutation in a nuclear energy system as a whole. In a contrast to fast reactors and accelerator-driven systems, fusion-driven transmutation reveals time to approach equilibrium that is comparable with the lifetime of transmuter and power associated with transmutation lies well within 5% of the total power of the nuclear energy system composed of fission reactors and transmuters.

Fusion-Driven Transmutation of Fission Product Cesium in its Elemental Form

Assuming fission reaction as a dominant energy source for a long-term perspective, the goal of transmutation of fission products is to cut their increasing accumulation and to keep their inventories at easily manageable level. Opposite to relatively short-lived 137Cs (T1/2=30yr) whose natural decay converge equilibrium mass to the level of order of 11 per GW of fission energy, an approach to similar equilibrium inventory for long- lived 135Cs (T1/2=2.3×106 yr) requires artificial transmutation that preassumes its isotopic separation in the most studies. The present paper addresses cesium transmutation without preliminary isotope separation that means an approach to equilibrium for all the isotopes including stable 133Cs. A high-flux blanket driven by Fusion Neutron Source with ITER-like parameters is proposed to transmute cesium in the elemental form. Transmutation efficiency is estimated in terms of equilibrium inventory and characteristic time to reach equilibrium both governed by the mean life-time of nuclides in transmuter. The analytical results show that the mean life-time of the target isotope 135 Cs is as short as 21 yr which is in more than order of magnitude shorter than achieved in advanced fission reactors. It reveals that one Fusion Neutron Source with ITER-like parameters could transmute elemental cesium from 23 PWRs, the fraction of power associated with transmutation being as small as 3%.

Accumulation and transmutation of spallation products in the target of accelerator-driven System

Analysis of the radiological burden of the spallation products (SP) was performed for various spallation targets (lead, tungsten, tin). The radiological burden was discussed in terms of toxicity based upon the concept of Annual Limit on Intake (ALI) shows that alpha-emitting rare earths (146Sm, 148Gd, 150Gd, 154Dy) are dominant. Their toxicity was estimated at equilibrium state with and without their transmutation. It is concluded that, in terms of toxicity, accumulation of SP in the target is quite comparable with transmutation of fission products (FP) in the blanket of Accelerator-Driven System (ADS).

Concept of erbium doped uranium oxide fuel cycle in light water reactors

This paper is aimed at the development of a fuel cycle concept for host countries with a lack of nuclear infrastructure. To minimize plutonium proliferation concern the adoption of long-life core with no fuel radiochemical treatment on site is suggested. Current investigation relies upon light water reactor technology and plutonium-free fresh fuel. Erbium doped to uranium oxide (enrichment 19.8%) fuel is selected as the reference. Such a high enrichment is selected in attempt to approach the longest irradiation time in one batch mode. In addition to that, uranium enriched up to 20% does not consider as a nuclear material for direct use in weapon manufacture. A sequence of two irradiation cycles for the same fuel rods in two different light water reactors is the key feature of the advocated approach. It is found that the synergism of PWR and pressure tube graphite reactor offers fuel burnup up to 140GWd/tHM without compromising safety characteristics. Being as large as 8% in the final isotopic vector, fraction of 238Pu serves as an inherent protective measure against plutonium proliferation.

Potential to approach the long-life core in a light water reactor with uranium oxide fuel

Abstract The central issue underlying this paper is related to spreading the benefits of nuclear power over developing countries with no nuclear infrastructure. This envisages the decreased proliferation concern along with minimizing the on-site fuel management. To satisfy these requirements, an approach is addressed to the long-life core in a light water reactor with uranium enrichment up to 19.5%. Reduced plutonium accumulation per total energy produced in such a core is a clear advantage from the viewpoint of proliferation resistance. The challenge of the long-life core necessitates the use of burnable poisons. It was found that erbium doped uranium oxide fuel helps to keep sufficient criticality up to 100 GWd/tHM burnup without compromising the safety parameters.

Effect of Transplutonium Doping on Approach to Long-life Core in Uranium-fueled PWR

The present paper advertises doping of transplutonium isotopes as an essential measure to improve proliferation-resistance properties and burnup characteristics of UOX fuel for PWR. Among them 241Am might play the decisive role of burnable absorber to reduce the initial reactivity excess while the short-lived nuclides 242Cm and 244Cm decay into even plutonium isotopes, thus increasing the extent of denaturation for primary fissile 239Pu in the course of reactor operation. The doping composition corresponds to one discharged from a current PWR. For definiteness, the case identity is ascribed to atomic percentage of 241 Am, and then the other transplutonium nuclide contents follow their ratio as in the PWR discharged fuel. The case of 1 at% doping to 20% enriched uranium oxide fuel shows the potential of achieving the burnup value of 100GWd/tHM with about 20% 238Pu fraction at the end of irradiation. Since so far, americium and curium do not require special proliferation resistance measures, their doping to UOX would assist in introducing nuclear technology in developing countries with simultaneous reduction of accumulated minor actinides stockpiles.

Radiation Dose as a Barrier against Proliferation for Advanced Fuel Compositions

The paper deals with the analysis of radiation barriers against proliferation focusing on denatured plutonium compositions and associated with the process of plutonium denaturing by some other heavy metals. The issue is discussed from the viewpoint of radiation dose induced by both gamma and neutron radiation, thus reflecting the technical and human resources the potential proliferators should have to meet the challenge of making a nuclear explosive.