Chain-reacting system self-sustaining

This strong absoring action of some elements renders a self-sustaining chain reacting system capable of control. By introducing neutron absorbing elements in the form of rods or sheets into the interior of the system for... 

Inasmuch as the reproduction ratio in any self-sustaining chain reacting system is reduced by the presence of impurities that absorb neutrons, such impurities can be introduced into the active portion of the structure in the... 

FIG. 18 is a diagram representing distribution of neu- neutron capture cross-section. Bismuth, deuterium and tron losses in our self-sustaining chain reacting system. helium are good moderating elements. The ability to... 

The concepts involved in an approach to critical with the fine control rod will be brought out in the latter part of the experiment. The approach to critical will be performed with the intention of showing the participant what is occurring in the reactor core during startup. The experiment will actually simulate the last steps of a criticality experiment, which is the basic experiment performed to determine the critical mass of a new system. The final result of the experiment will yield the position of the fine control rod at which the reactor becomes a self-sustaining neutron-chain-reacting system. 

The free radical reaction may be accelerated and propagated via chain branching or homolytical fission of hydroperoxides formed to generate more free radicals (equations (11.4), (11.5)). Free radicals formed can initiate or promote fatty acid oxidation at a faster rate. Thus, once initiated, the free radical reaction is self-sustaining and capable of oxidizing large amounts of lipids. On the other hand, the free radical chain reaction may be terminated by antioxidants (AH) such as vitamin E (tocopherols) that competitively react with a peroxy radical and remove a free radical from the system (equation (11.6)). Also, the chain reaction may be terminated by self-quenching or pol)rmerization of free radicals to form non-radical dimers, trimers and polymers (equation (11.7)). 

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