Structure of Rumor Disaster – On Fukushima Daiichi N.P.P. Unit 4 –

The misleading information spreads into the society, the people move on the basis of it. This mechanism, what I call “rumor disaster” is examined in this note. Authorities, specialists, intellectuals, and so on, oftentimes, might take part in this process. In this note, the spent fuel storage pool of Tokyo Electric Power Fukushima Daiichi N.P.P. Unit 4 is the case used for discussion because there are relatively abundant materials and the resulting impact to the society is very big.

Study on Radiation Dose Calculation of PWR Spent Fuel Storage and Transportation

With the rapid development of nuclear energy, spent fuel will accumulate in large quantities. Spent fuel is generally cooled and placed in a storage pool, and then transported to a reprocessing plant at an appropriate time. Because spent fuel is content with a high level of radiation, spent fuel storage and transportation safety play important roles in the nuclear safety. Radiation dose safety are checked and validated using source analysis and Monte Carlo method to establish a radiation dose rate calculation model for PWR spent fuel storage pool and transport container. The calculation results show that the neutron and photon dose rates decrease exponentially with increase of water level under normal condition of storage pool. The attenuation multiples of neutron and photon dose rates are 4.64 and 1.59, respectively. According to radiation dose levels in different water height situations, spent fuel pool under loss of coolant accident can be divides into five workplaces. They are supervision zone, regular zone, intermittent zone, restricted zone and radiation zone. Under normal condition of transport container, the dose rates at the surface of the container and at a distance of 1 m from the surface are 0.1759 mSv/h and 0.0732 mSv/h, respectively. The dose rates decrease with the increasing radius of break accident, and dose rate at the surface of the transport container is 0.278 mSv/h when the break radius is 20 cm. Transport container conforms to the radiation safety standards of International Atomic Energy Agency (IAEA). This study can provide some reference for radiation safety analysis of spent fuel storage and transportation.