nuclear-news

Mapping plutonium spread

To date, plutonium from the accident has been detected as far as 50 km from the damaged reactors. Researchers had previously thought that this plutonium, like the caesium, was released after evaporating from the fuel. But the new analysis instead points to some of it having escaped from the stricken plant in particulate form within fragments of fuel “captured” by the CsMPs…….

Implications for decommissioning

The researchers note that previous studies have shown that plutonium and caesium are distributed differently in the extended area around Fukushima, which suggests that not all CsMPs contain plutonium. However, they say that the fact plutonium is found in some of these particles implies that it could have been transported as far afield as the caesium – up to 230 km from the Fukushima plant.

As regards any threat to health, they note that radioactivity levels of the emitted plutonium are comparable with global counts from nuclear weapons tests. Such low concentrations, they say, “may not have significant health effects”, but they add that if the plutonium were ingested, the isotopes that make it up could yield quite high effective doses.

With radiation levels still too high for humans to enter the damaged reactors, the researchers argue that the fuel fragments they have uncovered provide precious direct information on what happened during the meltdown and the current state of the fuel debris. In particular, Utsunomiya points out that the composition of the debris, just like that of normal nuclear fuel, varies on the very smallest scales. This information, he says, will be vital when it comes to decommissioning the reactors safely, given the potential risk of inhaling dust particles containing uranium or plutonium.

The research is reported in Science of the Total Environment.   https://physicsworld.com/a/fukushima-may-have-scattered-plutonium-widely/