Cold fission

The excitation energy set free by the fission process is not distributed evenly amongst the primary fission fragments. In a small fraction of spontaneous fission events, which is called cold fission, the excitation energy is so small that no neutrons are emitted (neutron-less fission). This fraction is about 0.2% in case of Cf and about 3% in case of... 

Half-lives for proton emission, ot decay, cluster radioactivity, and cold fission processes have been calculated in the framework of an effective liquid drop model by Duarte et al. (2002). The comparison with experimental data shows that the model is very efficient to describe these different decay processes in a unified theoretical framework. 

Recent studies of SF of Cf with large y-ray detector arrays, Gammasphere (Lee 1990), revealed a new fission mode, cold fission with no neutron emission in the pair fragments of Zr-Ce and Mo-Ba (Ter-Akopian et al. 1994 Hamilton et al. 1995). Cold ternary SF, as Cf Ba + Sr -l- °Be, has also been identified by measuring the various y-transitions of these nuclei in coincidence (Ramayya et al. 1998). The use of the high-resolution triple y-coincidence technique can provide important information on very rare events in fission. 

The Model 412 PWR uses several control mechanisms. The first is the control cluster, consisting of a set of 25 hafnium metal rods coimected by a spider and inserted in the vacant spaces of 53 of the fuel assembhes (see Fig. 6). The clusters can be moved up and down, or released to shut down the reactor quickly. The rods are also used to (/) provide positive reactivity for the startup of the reactor from cold conditions, (2) make adjustments in power that fit the load demand on the system, (J) help shape the core power distribution to assure favorable fuel consumption and avoid hot spots on fuel cladding, and (4) compensate for the production and consumption of the strongly neutron-absorbing fission product xenon-135. Other PWRs use an alloy of cadmium, indium, and silver, all strong neutron absorbers, as control material. 

Weapons materials from production reactors were accumulated during the Cold War period as a part of the U.S. defense program. Prominent were tritium, ie, hydrogen-3, having a of 12.3 yr, and plutonium-239, 1/2 = 2.4 X lO" yr. The latter constitutes a waste both as a by-product of weapons fabrication in a waste material called transuranic waste (TRU), and as an excess fissionable material if not used for power production in a reactor. 

Polonium is used to eliminate static electricity in industrial processes, such as rolhng out paper, wire, or sheet metal in mills. Polonium is also sometimes used in brushes to remove dust from photographic film and in the manufacturing of spark plugs that make ignition systems in automobiles more efficient, particularly in extremely cold temperatures. It can also be used as a portable, low-level power source and, since polonium is fissionable, used in nuclear weapons and nuclear electric power plants. 

Most of the chemical and physical properties of imniloctium (hassium) are unknown. What is known is that its most stable isotope (hassium-108) has the atomic weight (mass) of about 277. Hs-277 has a half-life of about 12 minutes, after which it decays into the isotope seaborgium-273 through either alpha decay or spontaneous fission. Hassium is the last element located at the bottom of group 8, and like element 107, it is produced by a cold fusion process that in hassium s case is accomplished by slamming iron (Fe-58) into particles of the isotope of lead (Pb-209), along with several neutrons, as follows ... 

The cross sections for elements lighter than 113 decrease by factors of 4 and 10 per element in the case of cold and hot fusion, respectively. The decrease is explained as a combined effect of increasing probability for reseparation of projectile and target nucleus and fission of the compound nucleus. Theoretical consideration and empirical descriptions, see e.g. [61,62], suggest that the steep fall of cross sections for cold fusion reactions... 

Equations (5.7) and (5.8) are known as Carnot s equations. In Eq. (5.7) the smallest possible value of QC is zero the corresponding value of Tc is the absolute zero of temperature on the Kelvin scale. As mentioned in Sec. 1.4, this occurs at -273.15°C. Equation (5.8) shows that the thermal efficiency of a Carnot engine can approach unity only when TH approaches infinity or Tc approaches zero. On earth nature provides heat reservoirs at neither of these conditions all heat engines therefore operate at thermal efficiencies less than unity. The cold reservoirs naturally available are the atmosphere, lakes and rivers, and the oceans, for which Tc = 300 K. Practical hot reservoirs are objects such as furnaces maintained at high temperature by combustion of fossil fuels and nuclear reactors held at high temperature by fission of radioactive elements, for which T = 600 K. With these values,... 

The main features of cold fusion reactions with the spherical nuclei of Pb or ° Bi as targets are low excitation energies of the compound nuclei (Ex w 15 to 20 MeV) with the consequence of emission of only one or two neutrons, low probability of fission, and relatively high fusion cross sections otus- On the other hand, the reaction products have relatively small neutron numbers and short half-fives. Suitable projectiles are neutron-iich stable nuclei, such as " Ca, Ti, " Cr, Fe, Ni, Zn, and Kr. 

In the case of 8 -nitro-4 -etliylcarbonatobenzoyl-4-aminophenyl-arsinic acid, hydrolysis readily occurs with negligible fission at the amide linkage when the compound is boiled for a short time with normal alkali, but in the case of the corresponding derivative of 8-amino-4-hydroxy-phenylarsinic acid, hydrolysis with cold normal alkali causes appreciable fission of the amide linkage. The two compounds are represented by the structures ... 

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