Ben Fogle goes to the most radioactive place on Earth five years after the Chernobyl catastrophe. The world is facing unprecedented challenges, many of which, like Chernobyl, are the result of human activity.
The incident happened during a safety test designed to evaluate the steam turbine’s capacity to run the emergency feedwater pumps of an RBMK-type nuclear reactor in the event of a major coolant leak and simultaneous loss of external power.
When the power came back on and the reactor was stabilized, the operators removed a number of control rods that had exceeded operating procedure limits. The operators started the reactor to shut down once the test was finished. This action led to localized increases in reactivity within the reactor (i. e. «Positive scram,» etc.).
That caused fuel channels to burst and a sudden drop in pressure, which caused the coolant to flash to steam. As a result, there was a decrease in neutron absorption, which increased reactor activity and raised coolant temperatures (creating a positive feedback loop). The reactor core melted as a result of this process, which also caused steam explosions.
The reactor core was ruptured during the meltdown and explosions, and the reactor structure was completely destroyed. Following this, an open-air reactor core fire broke out, lasting until May 4 of that same year, during which time airborne radioactive contaminants were released and spread throughout the USSR and Europe. Approximately 70% of them landed 16 kilometers (9 point 9 miles) away in Byelorussia (now Belarus).
As much radioactive material as the initial explosion released was released by the fire. 36 hours after the initial accident, a 10-kilometer (6point 2 mi) radius exclusion zone was established in response to it, and 49,000 people were evacuated from it, primarily from Pripyat. Later, the exclusion zone was extended to a 30 km (19 mi) radius, and an additional 68,000 people had to be evacuated.
Inside Chernobyl with Ben Fogle