Controlled thermonuclear reactors

Analysis of the natural reactors at Oklo gives valuable information about the migration behaviour of fission products and actinides in the geosphere. Uranium and the lanthanides have been redistributed locally. Plutonium produced in the Oklo reactors did not move during its lifetime from the site of its formation 85-100% of the lanthanides, 75-90% of the Ru and 60-85% of the Tc were retained within the reactor zones. Small amounts of U, lanthanides, Ru and Tc moved with the water over distances of up to 20-50 m. 

Controlled thermonuclear reactors (CTR), also referred to as fusion reactors, are in the development stage. Operation on an industrial scale before the year 2050 is unlikely. 

For a controlled nuclear fusion reaction the following parameters are important  

The temperature must be 10 K, and nx must be 10 s m for the D-D reaction and 10 ° s m for the D-T reaction. The triple product nrT must be 5-10 s eV m . Since two particles are involved in each collision, the fusion power density increases with the square of the particle density. At 1 Pa (n = 3 10 ° m ) the power density is several tenths of a megawatt per cubic metre, and the required confinement time would be 0.1-1 s. Best results have been obtained so far with central ion temperatures of the order of xi4 10 K, particle densities of 5 10 m and confinement times of 2 s. 

Steady-state machines may be operated in a pulsed or continuous mode. In both cases, the fuel gases D and T, respectively, must be injected and the fusion products 

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The fission products and Cs can be transformed into shorter lived or stable products by charged particle or neutron irradiation. Charged particle irradiation would be very expensive, and irradiation by reactor neutrons would produce almost as much fission products as are destroyed. Therefore the use of intense accelerator driven spallation neutron sources for transmutation by n-irradiation has been suggested. If controlled thermonuclear reactors (CTR) are developed, their excess neutrons could be used for Sr transformation, but less efficient for Cs. 

It Is of Interest to project the deuterium requirements for use as a fusion fuel In controlled thermonuclear reactors (CTR). Robert Hlrsch, Director of the U.S.A.E.C. Division of Controlled Thermonuclear Research has predicted the production of significant amounts of fusion energy by 1980, and fusion power commercialization before the turn of the century (22). A report prepared by a group at Brookhaven National Laboratory (23) can be used for estimating energy and deuterium requirements in a future fusion-based energy regime. In which all fossil fuels (except for ship and petrochemical feed requirements) are replaced with synthetic fuels produced by D-D fusion reactors, and all electricity production is by CTR. They estimate that by the year 2020,... 

TNA PRO AB 6/2127. ZETA and Controlled Thermonuclear Reactor Project. TNA PRO AB 16/2364. Experimental fusion reactor, ZETA. 

Also in 1950 Sakliarov and Tamm proposed an idea for a controlled thermonuclear fusion reactor, the TOKAMAK (acronym for the Russian phrase for toroidal chamber with magnetic coiF ), which achieved the highest ratio of output power to input power of any fusion device of the twentieth centuiy. This reactor grew out of interest in a controlled nuclear fusion reaction, since 1950. Sakharov first considered electrostatic confinement, but soon came to the idea of magnetic confinement. Tamm joined the effort with his work on particle motion in a magnetic field, including cyclotron motion, drifts, and magnetic surfaces. Sakharov and Tamm realized that... 

Hashimoto et al. [ ] have described a multifilamentary NbaSn superconductor produced by heat treatment of a composite consisting of niobium cores and a two-component matrix of pure copper and a high-tin bronze (Sn-20 wt.% Cu). The technical feasibility and economic advantages of this technique have been evaluated in the present study. This study included consideration of the likely cost per A m and the overall current densities achievable with this new conductor design. Particular attention was devoted to high current (10 kA at 12 T) conductors suitable for application in magnets intended for experimental controlled thermonuclear reaction devices, such as the Fusion Engineering Research Facility (FERF) [ ] at Lawrence Livermore Laboratory and the tokamak-type experimental reactors. 

A reactor in which nuclear fusion takes place with the controlled release of energy. Although thermonuclear reactors do not yet exist, intense research in many parts of the world is being carried out with a view to achieving such a machine. There are two central problems in the creation of a self-... 

It IS often stated that unclear fusion tvill produce no radioactive hazard, but this is not correct. The most likely fuels for a fusion reactor would be deuterium and radioactive tritium, which arc isotopes of hydrogen. Tritium is a gas, and in the event of a leak it could easily be released into the surrounding environment. The fusion of deuterium and tritium produces neutrons, which would also make the reactor building itself somewhat radioactive. However, the radioactivity produced in a fusion reactor would be much shorter-lived than that from a fission reactor. Although the thermonuclear weapons (that use nuclear fusion), first developed in the 1950s provided the impetus for tremendous worldwide research into nuclear fusion, the science and technology required to control a fusion reaction and develop a commercial fusion reactor are probably still decades away. 

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