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Neutronics analysis of HYLIFE-II blanket for fissile fuel breeding in an inertial fusion energy reactor

A protective,60 cm thick flowing liquid wall coolant is investigated as energy carrier,and fusile and fissile breeder medium in an inertial fusion energy (IFE) reactor. Flibe as the main constituent is mixed with increased mole-fractions of heavy metal salt (ThF4 and UF4) starting with 2 mol% up to 12 mol%. For a plant operation period of 30 years,radiation damage values were found as DPA= 65 for 2 mol% heavy metal in the coolant,and remain practically constant with increasing heavy metal fraction,well below the presumable limit of DPA=100. Helium production values are calculated as 270 appm for 2 mol% heavy metal fraction,also being far below the limit value of 500 appm and remain at the same level with increasing heavy metal fraction. Such a flowing protective liquid wall extents the lifetime of the rigid first wall structure to a plant lifetime of 30 years. Fissionable metal salt in the flowing liquid enables one to breed high quality fissile fuel for external reactors by a self-sustaining tritium breeding for the fusion plant and increases plant power output. # 2002 Elsevier Science Ltd. All rights reserved.

Neutronic analysis of PROMETHEUS reactor fueled with various compounds of thorium and uranium

In this study, neutronic performance of the DT driven blanket in the PROMETHEUS-H (heavy ion) fueled with different fuels, namely, ThO2, ThC, UO2, UC, U3Si2 and UN is investigated. Helium is used as coolant, and SiC is used as cladding material to prevent fission products from contaminating coolant and direct contact fuel with coolant in the blanket. Calculations of neutronic data per DT fusion neutron are performed by using SCALE 4.3 Code. M (energy multiplication factor) changes from 1.480 to 2.097 depending on the fuel types in the blanket under resonance-effect. M reaches the highest value in the blanket fueled with UN. Therefore, the investigated reactor can produce substantial electricity in situ. UN has the highest value of 239Pu breeding capability among the uranium fuels whereas UO2 has the lowest one. 239Pu production ratio changes from 0.119 to 0.169 according to the uranium fuel types, and 233U production values are 0.125 and 0.140 in the blanket fueled with ThO2 and ThC under resonance-effect, respectively. Heat production per MW (D,T) fusion neutron load varies from 1.30 to 7.89 W/cm3 in the first row of fissile fuel breeding zone depending on the fuel types. Heat production attains the maximum value in the blanket fueled with UN. Values of TBR (tritium breeding ratio) being one of the most important parameters in a fusion reactor are greater than 1.05 for all type of fuels so that tritium self-sufficiency is maintained for DT fusion driver. Values of peak-to-average fission power density ratio, Γ, are in the range of 1.390 and ∼1.476 depending on the fuel types in the blanket. Values of neutron leakage out of the blanket for all fuels are quite low due to SiC reflector. The maximum neutron leakage is only ∼0.025. Consequently, for all cases, the investigated reactor has high neutronic performance and can produce substantial electricity in situ, fissile fuel and tritium required for (D,T) fusion reaction.

Neutronic investigation of a hybrid version of the ARIES-RS fusion reactor

Abstract A hybrid version of the ARIES-RS of the commercial 1000 MW el power plant design concepts is investigated. A 10 cm fission zone at the inner blanket leads to a blanket multiplication of M =1.946 with ThC fuel or M =3.03 with UC fuel and increasing the fusion power from 2170 to 4200 MW or to 6500 MW, respectively. Despite a partial replacement of the lithium zone by the fissile zone, tritium breeding remains still >1.05, which will be required for a self-sustaining fusion driver. In addition to fusion power amplification, substantial fissile material will be produced at start-up conditions with a fission breeding rate of 233 U=0.183 (with ThC) or 239 Pu=0.263 (with UC) per incident fusion neutron, which correspond to 4410 kg 233 U/year or 6500 kg 239 Pu/year, respectively, by a full fusion power of 2170 MW. Damage calculations are based on the neutron flux load of 3.7 MW/m 2 and 5.6 MW/m 2 and have resulted with DPA=31 and 78 at the inner and outer first wall, respectively. DPA limit on vanadium will then require a change of the first walls at the inner and outer blankets after ∼6.5 and ∼2.5 full power years, respectively. Helium production at the inner and outer first wall is calculated as 117 and 237 ppm, respectively. This would lead to a first wall change after ∼4 and ∼2 full power years at the inner and outer blankets, respectively. The spectrum softening in the fissile zone will cause a relatively lower material damage as compared with the pure fusion reactor design.

Numerical study on transient local entropy generation in pulsating turbulent flow through an externally heated pipe

This study presents an investigation of transient local entropy generation rate in pulsating turbulent flow through an externally heated pipe. The flow inlet to the pipe pulsates at a constant period and amplitude, only the velocity oscillates. The simulations are extended to include different pulsating flow cases (sinusoidal flow, step flow, and saw-down flow) and for varying periods. The flow and temperature fields are computed numerically with the help of the Fluent computational fluid dynamics (CFD) code, and a computer program developed by us by using the results of the calculations performed for the flow and temperature fields. In all investigated cases, the irreversibility due to the heat transfer dominates. With the increase of flow period, the highest levels of the total entropy generation rates increase logarithmically in the case of sinusoidal and saw-down flow cases whereas they are almost constant and the highest total local entropy is also generated in the step case flow. The Merit number oscillates periodically in the pulsating flow cases along the flow time. The results of this study indicate that flow pulsation has an adverse effect on the ratio of the useful energy transfer rate to the irreversibility rate.

Fissile fuel breeding with peaceful nuclear explosives

Neutron physics analysis of a dual purpose modified PACER concept has been conducted. A protective liquid droplet jet zone of 2 m thickness is considered as coolant, energy carrier, and fusile and fissile breeder. Flibe as the main constituent is mixed with increased mole-fractions of heavy metal salt (ThF4 and UF4) starting by 2 up to 12 mol.%. The neutronic model assumed a 30 m radius underground spherical geometry cavity with a 1 cm thick SS-304 stainless steel liner attached to the excavated rock wall. By a self-sufficient tritium breeding of 1.05 with 5 mol.% ThF4 ,o r 9 mol.% UF4 an excess nuclear fuel breeding rate of 1900 kg/year of 233 U or 3000 kg/year 239 Pu of extremely high isotopic purity can be realized. This precious fuel can be considered for special applications, such as spacecraft reactors or other compact reactors. The heavy metal constituents in jet zone acts as an energy amplifier, leading to an energy multiplication of M� /1.27 or 1.65 for 5 mol.% ThF4, or 9 mol.% UF4, respectively. As an immediate result of the strong neutron attenuation in the jet zone, radiation damage with dpaB/1.4 and He B/7 ppm after a plant operation period of 30 years will be well below the damage limit values. The site could essentially be abandoned, or the cavity could be used as a shallow burial site for other qualified materials upon decommissioning. Finally, the totality of the site with all nuclear peripheral sections must be internationally safeguarded carefully. # 2003 Elsevier B.V. All rights reserved.