Tokamak based hybrid systems for fuel production and recovery from spent nuclear fuel

Abstract

The effect of the internal elements of a tokamak with different coolants on the transmutation rate of longlived actinides is studied. The Monte Carlo method is used to calculate nuclear reactions in a homogeneous model of a blanket and in specific designs of a blanket. The neutron-physical calculations of a homogeneous model of a blanket showed that the absorption of neutrons by the central column of the tokamak and their moderation by the beryllium coating slow the transmutation rate to 35% of the initial value with the most efficient utilization of lead coolant. For water coolant, this effect is negligible. In a heterogeneous model of a blanket where water coolant is used, plutonium must be added to the actinides (50%/50%). The use of lead as the coolant will increase the transmutation rate of the actinides without using plutonium. In this case, it will be possible to reprocess spent nuclear fuel from more than 10 VVER-1000 in the JUST-T hybrid reactor.The limited nature of the fuel resources of modern nuclear power, the recovery from spent nuclear fuel, the attainment of a high safety level, and the transition to a closed fuel cycle are all problems which can be solved by developing largescale nuclear power based on fast reactors with natural safety [1,2]. However, such reactors are at the design and scientific work stage; it is difficult to predict their serial implementation. The sodium-cooled fast reactors which industry has adopted make it possible to close the fuel cycle, recover the spent fuel, and provide fuel for hundreds of years. However, world experience has shown that such reactors are expensive because hot and highly active sodium is used as the coolant and today's models (BN-600, -800) are not ready for building on a wide scale.The breeding of excess plutonium in technically perfected fast reactors is low (the breeding ratio 1.2-1.3). For this reason, for a closed fuel cycle where thermal reactors are replenished with plutonium produced in fast reactors it is necessary to produce 2-3 GW(e) by fast reactors for every 1 GW(e) from thermal reactors. Thus, the latter reactors will play a dominant role which will determine the economics of nuclear power. A different way to supply power to thermal reactors is also possible -secondary fuel (plutonium or 233 U) producers, which are more efficient than fast reactors, can be introduced. This problem can be solved by developing a hybrid thermonuclear reactor in which the fuel breeding zone (the blanket surrounding the plasma chamber) operates in the subcritical regime; this precludes the possibility of uncontrolled nuclear reactions [3]. In such a system, the thermonuclear fusion of deuterium and tritium serves as a stationary source of neutrons. Such facilities can be built on the basis of a tokamak [4][5][6][7][8][9][10] and open magnetic traps [11]. These facilities can supply fuel to thermal reac-

The Concept of a Hybrid Fusion-Fission Reactor Based on Tokamak Using a Blanket With Depleted Uranium

“…Диаметр твэла равен 1,1 см, толщина стенки 0,05 см. Эта схема модуля аналогична бланкету для трансмутации минорных актинидов проекта JUST-T [13]. Конструкция модуля бланкета представлена на рис.…”

“…В случае работы гибридного реактора в режиме трансмутации минорных актинидов (МА) присутствие лития слабо снизит скорость их деления. Максимальное энерговыделение в этом случае составит около 150 Вт/см 3 [13], а для 238 U эта величина 60 Вт/см 3 . Это говорит об отсутствии проблемы наработки трития для гибридного реактора в режиме трансмутации МА.…”

“…Ввиду необходимости учёта большого количества различных нуклидов и их реакций, а также неоднородности задачи для получения надёжных результатов были использованы численные методы расчётов. Как и в [13], нейтронно-физические расчёты проводились методом Монте-Карло (код MCNP-4B).…”

Three-dimensional model of DEMO-FNS facility considering neutronics and radiation shield problems

“…Tokamak plasma of the DEMO-FNS is a powerful generator of neutron flux and gamma radiation. The expected fusion power of the FNS tokamak has to be ∼40 MW [1, 2, 3, 4, 5, 6, 7]. This value corresponds to the expected source neutron yield of 1.4 × 10 19 n/s.…”

Analysis of fuel rejuvenation times in a fusion breeder reactor fuelled with a mixture of uranium-thorium oxides for the CANDU reactor

“…Fur ther more, the re ju ve na tion of spent fuel and the en rich ment of ura nium-tho rium fuel are per formed in HY BRID re ac tors by many re search ers. Azizov et al stud ied the trans mu ta tion of long-lived actinides in a TOKA MAK fu sion re ac tor cooled with dif fer ent coolants by us ing the Monte Carlo method [11]. Francois et al an a lyzed the trans mu ta tion of LWR spent fuel in a fu sion-fis sion HY BRID sys tem based on the TOKA -MAK con cept by con sid er ing mixed ox ide fuel and inert ma trix fuel [12].…”