beaches/sand accumlation?

Yes there is but it will entail expenses. The OP is concerned about radioactive materials accumulating in the beach sand and that is a valid concern. You need to realize that all elements have different weights. This difference means some elements will be lighter than water and others heavier. The radioactive elements are generally quite a bit heavier than water so it is reasonable to assume they will fall to the bottom of the ocean upon entry. But they do not because these particles are generally so small that the currents of the ocean keep them in suspension for long periods of time, sweeping them across large expanses as fast as the currents themselves move.
However, another factor comes into play. Bio acumulation, that is, the absorption of radioactive particles by living matter. In particular, in the oceans, those organisms that accumulate these materials first are the micro organisms, algaes, planktons, seaweeds, etc, These in turn are food for higher organisms that feed upon them so the radioactive materials are passed on and accumulated by them in turn.
As far as beach sands are concerned, radioactive particles, those whose weights are in the milligram and smaller, generally will just move along with the currents rather than settling anywhere BUT most beach sands have algaes living on them and this is where the radioactive matter accumulates; In the algaes clinging to the sand particles. (Eventually all particles will sink to the bottom and be trapped but that will take a very, very long time)
That is a cause for concern as a large amount can be accumulated in a short period of time. BUT the upside is that only so much can be retained by these algaes which is a limiting factor. In others words just so much and no more can accumulate. the rest will be swept along with the currents.
HOWEVER, there is a darker side to this. I think it is in Scotland that there was a nuclear incident. A reactor released large amounts of radiation into the North Sea along part of the coastline.
Yes, the beach sands were accumulating radioactivity BUT the real problem turns out to be from the winds.
What is happening is that the winds pick up water and blow it onshore. This has resulted in a line of radioactive deposition along the coastline that is very large and dangerous to the locals. The beaches (sands) themselves are not that bad (relatively speaking only!) but there is a distinct band about 50 yards from the beach where the spray tends to drop that is just dangerous. This band streches inland for a bit. This is a different form of accumulation by wind deposition and just as bad, probably far worse!!
The locals are warned not to go to the beach or to fish or swim there. It will be like that for a LOOOONG time.
So, if you are genuinely concerned about the radiation levels at your beach, I would suggest taking samples in certain places and having them checked carefully. The best spots would be the sand right at the waters edge at the time of low tide, the sands at the edge at high tide, and the sands or whatever at 10 yard intervals from 50 to 500 yards from the point of mean tide.
So that is a lot of work but the mapping that results will be extremely revealing.
Otherwise, just lay in the sun for a while and then check both sides :)