Fukushima: The current situation andЬ future plans

O. FA RID, Imperial College London, UK, K. S HIH, University of Hong Kong, Hong Kong, W. E. LEE, Imperial College London, UK and H. YAM ANA,

Kyoto University, Japan

DOI: 10.1533/9780857097446.2.744

Abstract: This chapter describes the Fukushima Daiichi nuclear power plant (NPP) accident starting with the reactors’ location and sequence of events which caused the accident. The amount of radioactive materials released and its composition, dispersion of radioactive materials over land and sea, contamination effects on food and the environment and radiation effects on human health are all addressed along with the current clean-up programme and future plans. However, it is expected that it will take 30-40 years to decommission the damaged facilities.

Key words: Fukushima, BWR reactors, contamination, dispersion, clean-up.

24.1 Introduction

The biggest nuclear disaster since Chernobyl in 1986 occurred at the Fuku­shima Daiichi nuclear power plants (NPP) on 11 March 2011 (Plate IX between pages 448 and 449). Fukushima was shaken by an earthquake measuring magnitude 9.0 on the Richter scale followed by a massive 14 m tsunami, which caused the deaths of over 20,000 people living along the eastern coast of Japan, and led directly to the shutdown of three reactors in operation. However, the 6 NPP on the Fukushima site were designed on the basis of an earthquake equivalent to magnitude 8.2 and a 5.7 m tsunami. The tsunami caused the unanticipated total loss of power supply because of the loss of the backup generators due to flooding from the tsunami. This power supply is necessary for cooling water circulation for residual heat removal from the reactor cores, and its loss is what eventually lead to severe damage [1] to the cores in the first three days along with degradation arising from the use of seawater for emergency cooling. As a result, high amounts of radioactive material were released into the atmosphere although, unlike at Chernobyl, only causing predominantly regional-scale contamination by radionuclides. The Japanese authorities announced an official ‘cold shut­down condition’ in mid-December, as the reactor temperatures had fallen
to below 80°C at the end of October 2011 [2]. Apart from cooling, the on­going task remains to prevent further release of radioactivity, particularly in contaminated water which has leaked from the three units. According to the Japanese government, the total amount of radioactivity released to date is approximately one-tenth that released during the Chernobyl disaster. However, the full extent and level of radioactive contamination remain unclear.

Добавить комментарий

Ваш e-mail не будет опубликован. Обязательные поля помечены *