Intelligent damage mitigation for BWR nuclear reactors

Chapter 611This paper deals with light water reactor, particularly BWR type nuclear power plants, similar to Fukushima Dai-ichi Nuclear Power Plant with reactors equally vulnerable to core-melt accidents. It first re-iterates the observations and assertions made by Shinozuka (Shinozuka 2012) to recognize that the core-melt is the most critical damage event that must be mitigated by aggressive mitigation procedures if it cannot be prevented. In this regard, it is noteworthy to observe that U.S. Nuclear Energy Institute (NEI) recently intro-duced a procedure FLEX (NEI 2012) for emergency preparedness. This paper however proposes a different procedure as promoted by Shinozuka earlier (Shinozuka 2012) which is now named “Direct Core Cooling System” (DCCS). DCCS is developed making use of mobile closed-circuit water chilling system in such a way that pumps, a part of this system, are (1) directly connected by pipes to the core, (2) while minimizing their connections with any other reactor components. (1) and (2) above indicate the care that must be exer-cised not to get trapped by 3 pitfalls related to such connections. Any one of these pitfalls if trapped can com-promise effectiveness of DCCS. The mobile water chilling system is originally introduced to similar line of research by Cheung (Cheung 1991 & 2012). The cooling action by DCCS takes place as soon as intelligent sensors in the sense of engineering cybernetics detect initial sign of core-melt, and contain the core-melt lead-ing it to a cold shut down

Explosibility assessment of dusts produced in the recycling process of electrical appliances

Explosibility of dusts produced in the recycling process of electrical appliances was investigated. Polyurethane and plastic dusts, produced by shredding discarded electrical appliances, were mainly used as the sample. Various explosivity indexes, such as the minimum explosive concentration, K$_{\rm st}$ value, the maximum explosion pressure, the influence of coexisting explosive gases on the explosibility of dusts, the oxygen concentration to reduce the risk of dust explosion, and the ignition temperature of the dust cloud were examined. These experimental results were applied to improve the safety of operation of recycling facilities