Economical and neutronic performance of HYLIFE-II with mixture of 90% flibe+10% UF4 (or ThF4)

This work investigated the neutronics behavior and the economics of the HYLIFE-II reactor with ThF4 and UF4, which produces an electrical power of 1 GW from the fusion power of 2.857 GW during the operation period of 30 years. The use of ThF4 and UF4 is realized by a mixture zone consisted of 90% flibe (Li2BeF4) and 10% fuel, instead of 100% flibe coolant. The mixture compositions are selected as 90% flibe + 10% UF4, 90% flibe + 10% ThF4 and 90% flibe + 5% UF4 + 5% ThF4. The capacity factor of the reactor is 0.75. The mixtures, with zone thickness of 65 cm were circulated with periods of 20.22, 19.89 and 20.11 s during the operation period of 30 years, respectively. In addition, for flibe + UF4, power stabilization by means of plutonium separation from the mixture was applied

Rejuvenation of the CANDU spent fuel in (D-T)-driven hybrid reactors

The possibility of Canada deuterium uranium reactor (CANDU) spent-fuel rejuvenation in deuterium-tritium (D-T)-driven hybrid reactors having 17.8 cm of fissile zone thickness is investigated for various plasma chamber dimensions (DR = 18.7, 118.7 218.7, and 418.7 cm) with a linear fusion neutron source (plasma dimension is assumed as DR/2) under different first-wall loads (P-w = 2, 4, 6, 8, and 10 MW/m(2)). The behavior of the spent fuel is observed during 36 months for discrete time intervals of Delta t = 15 days and by a plant factor of 75%. The fissile fuel zone is consider-ed to be cooled with three different coolants: gas (He or CO2), Flibe (Li2BEF4), and natural Li

Power stabilization and temporal performance of a peaceful nuclear explosion reactor with a mixture of 90% flibe+10% UF4 (or ThF4)

This work investigated the power stabilization and the temporal neutronic behavior of a peaceful nuclear explosion reactor (PACER) with ThF4 and UF4, which produces an electrical energy of 1.2 GW from fusion explosions of 8.13 x 10(12) J to be repeated every 40 min during the operation period of 30 year. The use of ThF4 and UF4 is realized by a mixture zone consisted of flibe and fuel. instead of full flibe zone. The mixture compositions determined by volume fraction are 90% flibe +10% UF4, 90% flibe +10% ThF4 and 90% flibe +5 % UF4 + 5 % ThF4. The capacity factor of the reactor is 0.75. The cylindrical explosion chamber has a radius of 30 m and a height of 75 m. The mixture mass of 18,000 tonnes having a zone thickness of 5 m were circulated during the operation period. The mixture zone would be subdivided into jets so that the gas and the vapor bypasses the liquid as it vents and does not accelerate the liquid mixture to high velocities. The selected volume fraction is 75% void +25% mixture. The use of fuel materials in the PACER reactor resulted in high-energy production, sufficient tritium breeding and significant fissile fuel breeding. The averages of tritium breeding ratio (TBR) values over 30 years are between 1.1 and 1.17. Generally, the mixtures with UF4 show better performance than the mixture with ThF4. For the mixtures with ThF4, ThF4 + UF4 and UF4, the energy production without the separation process reached from approximate to1430 MW (electric), 1700 MW (electric) and approximate to2000 MW (electric) to approximate to1900 MW (electric), approximate to2150 MW (electric) and approximate to2320 MW (electric), respectively. The reached cumulative fissile fuel enrichments in the fuel (CFFE) in percentage are 1.8, 2.45 and 2.4%, respectively. The fuel obtained from the PACER could be used as a nuclear fuel only in the CANDU and the advanced CANDU In addition, the stabilization process is performed by means of the plutonium or uranium fuel separation from the mixture, after the energy output of the reactor reaches 1600 MW (electric), 1800 MW (electric) and 2000 MW (electric) at the operation periods of 11, 6 years and 2 months, respectively. At the end of the separation process, the separated fuel amounts are about 15, 374 and I I tonnes, respectively. The CFFE values of the separated fuel at the end and at the start up of the separation process are 99.36 and 99.23%, 1.13 and 3.9%, and 99.99 and 99.2%, respectively. The CFFE values of the remained fuel at the end of the separation process are approximate to0.7, and 2.2%, approximate to0.7%, respectively. Consequently, in the evaluation in terms of sufficient tritium breeding, high energy production, significant fissile fuel production and the nuclear weapon hazard of the fuel, the mixture of 90% flibe +5% ThF4 + 5% UF4 exhibited the highest performance. (C) 2004 Elsevier B.V. All rights reserved

Rejuvenation of the LWR spent fuel in (D-T) driven hybrid reactors

The possibility of LWR spent fuel rejuvenation in (D, T) (Deuterium and Tritium) driven hybrid reactors having 12.5 cm of the fissile zone thickness is investigated for various plasma chamber dimensions (DR = 18.7, 118.7, 218.7 and 418.7 cm) with a linear fusion neutron source (Plasma dimension is assumed as DR/2) under different first wall loads (P-w = 2, 4, 6, 8 and 10 MW m(-2)). The behavior of the spent fuel is observed over 36 months for discrete time intervals of Delta t = 15 days and by a plant factor of 75%. The fissile fuel zone is considered to be cooled with three different coolants, gas (helium or CO2), Flibe (Li2BeF4) and Natural lithium. As a result of the calculation, in the case of the first wall load and the plasma chamber, dimensions are selected to be high, although the first wall material was damaged considerably by the high neutron flux (DPA > 100 and He > 500 ppm for P-w > 2 MW m(-2) over 3 years of operation) and maximum temperature in centerline of the fuel rod (T-m) has reached the melting point (T-m > 2600 degrees C for P-w > 6 MW m(-2) and DR > 1 m), it was observed that the neutronic performance of hybrid reactor improved unnegligibly. For DR = 18.7 cm, at the beginning of rejuvenation, TBR (Tritium Breeding Ratio) values being about 1.35, 1.11 and 1.39 for gas, Flibe and Natural lithium, respectively, the end of the rejuvenation increased to 1.39, 1.17 and 1.43 for 2 MW m(-2) and to 1.55, 1.39 and 1.57 for 10 MW m(-2). In addition, the blanket energy multiplication (M) increase 5.10, 4.87 and 4.82 for 2 MW m(-2) and to 6.55, 7.04 and 6.04 for 10 MW m(-2) from 4.67, 4.24 and 4.46, respectively. For only Flibe, when the preferred DR value is about 1 m, M values increased to 5.70 and to 9.5 from 4.43 for 2 MW m(-2) 10 MW m(-2), respectively. At the same conditions, average CFFE values indicating the rejuvenation performance increased to 3.27%, 3.80% and 3.21% for 2 MW m(-2), to 6.71%, 8.74% and 6.52% for 10 MW m(-2) from 0.418%, respectively. For Flibe coolant, while the same CFFE value is 11.5% about DR = 1 m, it is 11.9% about DR = 4 m. The contribution of a large plasma chamber (DR > 1 m) to neutronic performance can be neglected. The best rejuvenation performance and neutron economy has been shown by Flibe. For all cases, the denatured character of the initial fuel charge remains denatured for all investigated cases over the whole plant operation period in a hybrid reactor, although the plutonium duality increases continuously during the rejuvenation process. In addition, our calculations have proved that the effects of the important fission products (Xe-135, Sm-149) and plasma densities up to 10(21) (D + T)/cm(3) can be neglected on the neutronic performance of hybrid reactor which is rejuvenating LWR spent fuel. (C) 1998 Elsevier Science S.A. All rights reserved

Investigation of the flattened fissile fuel enrichment possibility with a (D, T) driven hybrid blanket cooled by flibe (Li2BeF4)

This work investigated the possibility of the fuel production with flattened cumulative fissile fuel enrichment (CFFE) at the hybrid reactor, to be cooled by the flibe (Li2BeF4) and fueled by UO2 with a LWR fuel rod and CANDU fuel rod diameters, LWR spent fuel and CANDU spent fuel, with an original fuel rod diameter during the operation period of 5 years. For that purpose, the new fuel zone structure is provided by means of the ratio of the flibe to fuel per fuel row in the fuel zone being varied. Neutronic performance of the (D, T) driven hybrid blanket with this fuel zone is followed by a plant factor of 75% under a. first wall load of 5 MW/m(2). The fuel row numbers are selected as 10. For all fuels, the possibility of the fuel production having almost the same CFFE in all fuel rows of the fuel zone of the hybrid blanket is possible by a deviation of 2%. Moreover, the fissile fuel production capability of the suggested blanket increased considerably. However, tritium breeding ratios and the displacement-per-atoms (dpa) values in the first wall and clad material are almost not affected by this blanket structure, the energy production decreased slightly. At the end of the operation period of 5 years, the CFFE value reached approximate to8.5, approximate to9.3, approximate to8.4 and approximate to8.2% for UO2 with LWR rods, LWR spent fuel, UO2 with CANDU rods and CANDU spent fuel, respectively. The remaining fuel from hybrid blankets with CANDU and LWR spent fuels have enough safety from the viewpoint of the plutonium non-proliferation since the isotropic percentage of Pu-240 in the produced plutonium is higher than 7%. However, other cases with UO2 fuel can reach sufficient safety after an operation period of 30 months. (C) 2001 Elsevier Science Ltd. All rights reserved

Determination of main reactor parameters for flibe (Li2BeF4) cooled peaceful nuclear explosive reactors (PACER)

This study analyzed main reactor parameters such as vapor production possibility, explosion chamber volume, equilibrium pressure-temperature, and neutronic behavior of a PACER (peaceful nuclear explosive reactor) producing electrical energy by means of repetitive explosions during certain periods for different values of coolant zone position (DR) and coolant zone thickness (DRc) with enough tritium breeding and more fusion energy absorption. Flibe (Li2BeF4) with different volume fractions is preferred as a coolant. In addition, the flibe inlet temperatures were selected as T-in = 823 K and 1540 K

Improvement of the neutronic performance of the hybrid reactor rejuvenating spent fuels using various moderators

Effects on the neutronic performance of the hybrid blanket rejuvenating light water reactor and CANDU spent fuels of moderators (Be, C, and D2O) inserted between the fusion chamber and the fissile zone of deuterium-deuterium and deuterium-tritium-driven hybrid reactor were investigated to obtain the best rejuvenation performance and more energy production. The calculations were carried out for different thicknesses of the moderator zone (DR). In addition, to eliminate focal heating, the analysis was also repeated for reduced radius of the spent fuel rods in the first and the second fuel rows of the fissile zone

Neutronic and thermal analysis of a peaceful nuclear explosion reactor

Thermal and neutronic behavior of a peaceful nuclear explosion reactor (PACER) producing approximate to1.2 GWe electrical-power from fusion explosions in a cylindrical explosion chamber (radius = 30 m, height = 75 m) are analyzed. For determination of flibe mass (m) required for safe operation temperatures and pressures with enough tritium breeding ratio (TBR) and high M (fusion energy absorption ratio), neutronic calculations are carried out for different coolant zone positions (DR) and coolant zone thicknesses (DRc) Inlet pressure and temperatures (T-in) of flibe are 1 atm, and 823 and 1540 K

NEUTRONIC INVESTIGATION OF A POWER-PLANT USING PEACEFUL NUCLEAR EXPLOSIVES

A neutron physics analysis of the modified PACER concept was conducted to assess the required liquid zone thickness of which the volume fraction is 25% in the form of Li2BeF4 (Flibe) jets and 75% as void. These liquid jets surround a low-yield nuclear fusion explosive and protect the chamber walls. The neutronic calculations assumed a 30-m-radius underground spherical geometry cavity with a 1-cm-thick stainless steel liner attached to the excavated rock wall. Achievement of tritium breeding ratios of 1.05 and 1.15 requires a Flibe thickness of 1.6 and 2.0 m, respectively, which results in average energy densities of 24 900 and 19 085 J/g. Our calculations show that for a Flibe zone thickness >2.5 m, the activation of the steel linear and rock would be low enough after 30 yr of operation that the cavity would satisfy the U.S. Nuclear Regulatory Commission's rules for ''shallow burial'' upon decommissioning, assuming other sources of radioactivity could be removed or qualified as well. This means that upon decommissioning, the site could essentially be abandoned, or the cavity could be used as a shallow burial site for other qualified materials