Human Factor Analysis of JCO Criticality Accident

Abstract

The criticality accident that occurred on September 30, 1999 at a uranium processing plant in Tokai-mura was an unprecedented nuclear accident in Japan, not only because it caused deaths of two workers due to radiation casualty but also because it called for evacuation and sheltering indoors to nearby residents. The accident was not directly caused by failures or malfunctions of hardware but by workers' unsafe action deviated from the approved procedure. It was a typical organizational accident in that several organizational factors worked behind. This article is to analyze various causal factors that lead to the accident, including situational factors of workers' unsafe action that triggered the accident, operational and business management of the company, and nuclear safety regulation by the government. It also discusses problems of emergency response after the accident.

A cognitive approach to safe violations

“…On December 30, 1999, in Tokaimura (Japan), a criticality accident occurred at the JCO nuclear fuel processing plant, causing the death of two workers. The immediate cause of the accident was the pouring of approximately 15kg of uranium into a precipitation tank, a procedure requiring mass and volume control (unless otherwise stated, the material in this section is from Furuta et al (2000)). The workers' task was to process seven batches of uranium in order to produce a uranium solution.…”

“…Previous successful attempts at reducing the cycle time led uncontrolled actions to become the norm at JCO (Blackman et al, 2000). These management issues are discussed extensively in Furuta et al (2000).…”

How the Fukushima Daiichi Accident Changed (or not) the Nuclear Safety Fundamentals?

“…Before the JCO criticality accident (JCO) [2], which occurred in 1999, emergency response that requires evacuation of nearby residents had been a taboo in Japanese nuclear development. As an aftermath of JCO, Act on Special Measures Concerning Nuclear Emergency Preparedness was enacted, and emergency response drills were enforced in each prefecture of major facility sites.…”

Secourir un train en panne : limites et difficultés à l’écriture des règles de sécurité

“…Ces deux systèmes et logiques coexistent et s'opposent dans l'organisation. Ces travaux forment la base de la réflexion de Reynaud mais l'auteur va progressivement 6 Dans des cas extrêmes, cette hyper-prescription peut induire des dérives et conduire à la catastrophe (Furuta, Sasou, Kubota, Ujita, Shuto, & Yagi, 2000 ;Snook, 2000 ;Vaughan, 2001). dépasser cette distinction classique pour montrer que ces deux systèmes ne sont pas antagonistes, mais complémentaires.…”