Furthermore, it would take a combination of extreme events to make things dangerous in Tokyo (nuclear re-criticality, steam explosion) etc all of which are being rendered less and less likely as time passes and the heat decay process progresses.
The heat from decay is lessening day by day, and the latest thermal imaging reports indicate temperatures of less than 100 degrees centigrade in reactor units 1, 2 and 3.
Once the reactor has shut down, there remains "decay heat" from traces of other radioactive isotopes.
The tsunami destroyed the diesel generators that provide power to drive the pumps that circulate the water coolant through the reactor that removes decay heat.
FORBES: Explainer: What Caused The Incident At Fukushima-Daiichi
Without an active removal of decay heat, the reactor was adding heat to the water faster than it was taking it out, and the temperature was rising.
FORBES: Explainer: What Caused The Incident At Fukushima-Daiichi
Thermoelectric coupling uses heat from the decay of a radioactive fuel (as opposed to the full-scale nuclear fission which powers a reactor on Earth) as its energy source.
ECONOMIST: A more efficient way to make electricity in spacecraft
They will always have to contend with decay heat.
FORBES: Explainer: What Caused The Incident At Fukushima-Daiichi
It will be necessary for some time to actively cool the reactors while the decay heat continues to decrease, but within a few months it will be possible to depressurize the reactors and assess their internal states.
FORBES: Explainer: What Caused The Incident At Fukushima-Daiichi
But as that hope faded and the need to remove the steadily-decreasing decay heat remained, operators at Fukushima-Daiichi took measures that would cool the reactors but would ruin them for future operation, such as the decision to try to cool the reactors with seawater.
FORBES: Explainer: What Caused The Incident At Fukushima-Daiichi
Although solar panels will work on spacecraft at that distance, the desire for sufficient energy to drive many instruments means any mission would really need to go with radioisotope thermal generators (RTGs) - solid state electrical generators powered by the heat of radioactive decay.
BBC: NEWS | Science/Nature | Europe tells US: 'Come to Europa'
The heat that keeps the core of the earth molten is primarily radioactive decay -it is what makes rock into liquid lava.
应用推荐