Sarcophagus
At 01:23:40 on 26th April 1986, a huge explosion literally blew the lid off reactor number 4 and with it, spewed out tonnes of radioactive material as far away as the UK and Ireland. Forty seconds prior to the explosion an experiment to test safety devices within the reactor had been initiated. Although the subsequent inquiry apportioned blame as 'operator error', the accident happened due to a combination of events converging with deadly effect. In a nutshell, the night crew were to perform a safety test but weren't really trained for the job as it had been kind of thrust upon them. A little like asking your butcher if he'll give you a haircut. Certain important safety devices were switched off, the design of the reactor was flawed and the result was an intense build up of thermal heat inside the reactor. The raging graphite fire was almost impossible to extinguish, but when it was, a hastily constructed sarcophagus was built around the reactor.
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It's important to note that it was a steam and not a nuclear explosion which occurred. Regulating the power wihin a reactor is rather like pedaling a unicycle. Go too slowly and you'll fall off, but equally, if you pedal too hard you'll also end up on the floor. In nuclear power terms, the stable state should've been around 3.2 GW, but the power dropped to a fraction of the that and then suddenly increased by ten fold to around 30 GW causing the explosion. Of the 180 tonnes of plutonium wihtin the reactor, only 8% of it ignited. The rest remains encased within and still obviously poses a huge problem. Here the reading is 0.462 R, around seventy times the usual levels. | Time to get away
In fact, the accident only came to light three days later when radioactive particles had drifted to a Swedish nuclear facility, triggering alarms there. After investigating and ruling themselves out, the source was traced to Chernobyl. Pictures lots of nuclear scientists, hands in their pockets, whistling innocently when confronted with the evidence from The West. |
