Notable Ethics Failures

Chernobyl Disaster

On 26 April 1986 reactor number four at the Chernobyl Nuclear Power Plant, near Pripyat in the Ukrainian SSR, suffered a massive, catastrophic power excursion resulting in a steam explosion which tore the top from the reactor exposing the core. The plant had no containment structure as does, for example, the three-mile-island reactor. Further explosions and the resulting fire sent a plume of highly radioactive fallout into the atmosphere and over an extensive geographical area. Four hundred times more fallout was released than had been by the atomic bombing of Hiroshima. The death toll has been estimated to be up to 4000 but only about 56 deaths are directly attributable to the accident.

The accident occurred because a new safety device was being tested during shutdown at the end of the plant's first fuel cycle. The device was supposed to supply electricity to cooling pumps for 60 seconds during abnormal shutdown. This was necessary because it takes 60 seconds for backup diesels to get up enough power to do the job. Without power for just a few seconds the lack of coolant would cause a major catastrophe. The catastrophe would be the worst possible (for technical reasons) if most of the fuel had already been spent.

Some political pressure resulted in the reactor going online before the device was adequately tested and it was not installed. The director of the Chernobyl station signed a document declaring the reactor ready - if he had not done so thousands of people would not have received bonuses or other awards. Records were falsified to hide all this.

The plant operated for two years without the safety device. At that point the plant had to be shut down to refuel. The station managers saw this as an opportunity to install the device and test it. Procedures for the test were planned. The day shift was quite competent and familiar with these procedures and the shut down was scheduled during that shift.

As fate would have it, a regional station suddenly went offline and Chernobyl was requested to stay online to make up the difference until demand diminished sufficiently. It wasn't until 11:00PM that permission was given to continue the shut down. By that time the day shift was home, the evening shift was packing up and the night shift was about to start work. The shutdown process would have to continue while one shift was leaving and the other arriving. The night shift did not understand the procedures and was not prepared for the shutdown. The following dialogue between two personnel was recorded:

    worker: What shall I do? In the programme there are instructions of what to do, and then a lot of things are crossed out.
boss of worker: Follow the crossed out instructions.

The sequence of events during the shutdown was as follows:

  1. The plan called for the power to first be reduced to about 30%. But the control rods were inserted too far.

  2. Because of this, high levels of xenon-135 were produced. The xenon absorbed neutrons causing the reactor to near-shutdown output levels.

  3. To continue the test, power had to be restored. But the night crew incorrectly assumed that the loss of power was due to a malfunction in an automatic power regulator. So they decided to pull the control rods out manually - in this case they were pulled out too far - way beyond safe limits - because the reactor was not delivering the power it should be because of those pesky xenon molecules.

  4. The test was continued. At 1:00AM the water flow was increased, according to the instructions. The extra water lowered the core temperature but also decreased reactor power. Hence the control rods were removed further - almost completely.

  5. This caused an unstable situation. The automatic shutdown system was supposed to cause a shutdown at this point but the operators decided to disable it. The unstable condition of the reactor was not known to the crew at this time.

  6. In accordance with the test instructions, the stream to the turbines was shut off. This caused a decrease in water flow since the pump speed was reduced.

  7. Reduced water flow resulted in heat buildup which caused boiling of some of the water - thus steam voids were produced. Power increased. Lots of neutrons were generated because of this. The xenon was not sufficient to absorb all these new neutrons. A runaway state was entered - the crew had lost control since the rods were removed and the automatic systems shut off.

  8. The operators pressed the SCRAM button.

  9. The graphite rods began to reinsert but the bad design had them displace coolant as they entered the reactor! The SCRAM increased power further! The core overheated! Some control rods broke and became stuck so rod insertion stopped about 1/3 of the way in!

  10. Within seven seconds power output was 10 times greater than under normal operating conditions!

  11. Increased steam ruptured coolant pipes. Fuel rods melted and reached the water of the flooded basement.

  12. Thirteen seconds later a steam explosion took place, blowing the 2000 ton lid off the reactor and ejecting fragments from the plant. Hydrogen began to build, probably due to the reaction of red-hot graphite with water.

  13. Three seconds later the hydrogen exploded. A graphite fire was started.

  14. Radiation monitoring equipment did not function - many who did their best to save the plant died a few weeks later from radiation poisoning.