Alpha radiation is easily shielded from external exposure, but for that exact reason it's also the most damaging; gamma radiation, for instance, will mostly pass right through you, while alphas will deposit all of their energy right into your cells. They're shielded by your dead skin, but if you ingest or inhale them, then there's no dead skin to protect you, and all that radiation goes straight into your cells.
In fact, according to the weighting system that converts joules of energy absorbed (Grays) to severity of radiation dose (Seiverts), a joule of alpha radiation is 20 times worse than a joule of X-rays, beta radiation, or gamma rays.
And it's ingestion or inhalation that we're worried about from environmental contamination; not that the environment itself would become so radioactive, Fallout-style, that you'd take rads just from standing around - but that radioactive dust from demolition might get into the air, or that contaminants might leak into the groundwater.
Yeah, but - context. We're talking about leaving a disused reactor around in some type of safe manner. Ideally it won't be leaking... but some radioactive material is still in it. Aren't the beta & gamma radiators more dangerous, even as far as irradiating other parts of the structure itself is considered?
Neither beta nor gamma radiation will "activate" other parts of the structure to make them radioactive themselves; only neutron radiation (which can convert stable isotopes into unstable isotopes with more neutrons in them) can do that.
Nor will they weaken the structure.
So as long as people don't enter the reactor without proper precautions, there's really no reason to worry about radiation inside it. And this problem can be solved pretty well with a fence and warning signs.
> So as long as people don't enter the reactor without proper precautions, there's really no reason to worry about radiation inside it. And this problem can be solved pretty well with a fence and warning signs.
The buildings being designed as a bunker also helps. Just add a single guardian and his dog just to be sure nobody is actively trying to break through the concrete walls and you're good to go.
In fact, according to the weighting system that converts joules of energy absorbed (Grays) to severity of radiation dose (Seiverts), a joule of alpha radiation is 20 times worse than a joule of X-rays, beta radiation, or gamma rays.
And it's ingestion or inhalation that we're worried about from environmental contamination; not that the environment itself would become so radioactive, Fallout-style, that you'd take rads just from standing around - but that radioactive dust from demolition might get into the air, or that contaminants might leak into the groundwater.