Hi checkmate. I have the same problem in my underground office where I test many different ideas for Netc.com and my family. There are two ways to get the radiation Or (Radon) out of your basement. My problem was my GC was testing over 700 cpm on a filter in my basement so the first idea was to suck the radiation out by putting a fan in a 4" pipe, to the outside. This is the common way most people remove Radon from their basement. I needed fresh air in my basement so I reversed the fan and it now blows positive pressure in my basement. It is working great, my radiation has dropped to 25 cpm on the filter. Now the radiation must go around my house because of the positive pressure.
The next thing I did was to get the humidity out, it was 95% some days. I bought a dehumidifier that runs off 12 volts and connected it to my solar panel. It dropped it from 95% to 68% in Arkansas. That was great too. There are always solutions, you may not like them.

Excellent solve. This should be at the top of my list of things to do. I live in a 1st floor apartment with a concrete slab floor and was running a HEPA air purifier long before I became a member here.