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Kanamori, Masashi
JNC TN8440 2001-018, 50 Pages, 2001/12
JNC-TN8440-2001-018.pdf:1.31MB
On September 30 at around 10:35 AM, criticality accident occurred at the JCO's conversion building in Tokai-mura. Since criticality accident had not been anticipated, neither devices for termination of criticality accident nor neutron detectors were available. Immediately after the information of the accident, our emergency staff (Japan Nuclear cycle development institute staff) went to JCO site, to measure the intensity of neutrons and gammas. There were four main tasks, first one was to measure the radiation intensity, second one was to terminate the criticality accident, third one is to alert the residents surrounding the JCO site, fourth one is to evacuate the employees in the site. These tasks were successfully performed until October 1. This paper describes about how these operations were performed by the relevant staffs.
Himeno, Yoshiaki; ; Kawada, Koji*; Kawabe, Ryuhei*; ; ; Miyaguchi, Kimihide
PNC TN941 85-130, 65 Pages, 1985/09
Test of sodium fires in an auxiliary building of the fast reactor has been conducted by use of a test rig in which reduced scale models of a sodium pipe, a floor liner, a sodium drain pipe, and a smothering tank were installed to simulate the configuration of fire mitigation systems in the reactor. In the test, a 150kg sodium at temperature of 505 
C was spilled from the model sodium pipe at flow rate of 1 
/sec for 3 minutes. Then a whole accident sequence that starts from a sodium spill and ends at a self-extiguishment of fire within the smothering tank was studied. From the test results obtained and through their analysis, the following conclusions were drawn. (1)A whole sodium leak and fires accident sequence proceeded as expected in the Monju design, i,e., a spilled sodium was smoothly drained into the smothering tank via the floor liner and the drain pipe, then sodium fire was self-extinguished in the smothering tank. (2)In regard to the model sodium pipe, failures of the thermal insulation jackets due to sodium corrosion and due to generated sodium combustion heat are not found. The thermal insulation jackets kept its original geometries and functioned propely as a barrier to prevent the dispersion of spilled sodium into the atmosphere during the test. No flow blockage of a spilled sodium occured both on the floor Liner and in the drain pipe. Combustion heat of mixed fires (a columnar fire and a pool fire) that occured within an accident cell of the test rig was determined to be 1.6 times of that of a pool fire. This value is not so large as expected and indicates that the mild fires proceeds during the test. (3)With the smothering tank, temperatures data of sodium, steel liner, perlite concrete, and structural concrete were obtained. The data of concretes indicated that the structural concrete was not heated so high as to interfere its structural integrity. A total water released from the concretes per unit surface area of the liner ...
Takahara, Shogo
no journal, ,
Radiation protective actions (e.g. evacuation, sheltering) are carried out in a nuclear accident to reduce risks due to radiation exposures. While these actions can reduce the risks, they can also cause behavioral restrictions, and health damage from actions themselves. In the present study, to explore prerequisites of justification for introducing protective actions, we carried out an ethical-analysis on the experiences of the Fukushima Daiichi Nuclear Power Plant accident, and found the issues to achieve ethical values recommended by the International Commission on Radiological Protection. Our analysis showed that to justify the protective actions in terms of ethical aspect, it is necessary to consider at least risk trade-off and paternalistic intervention.