I recommend this guy's YOU TUBE channel to monitor radiation. There have been others that have tried this but don't know a fraction of what they're talking about. This guy describes himself as a "novice". I realize he's more than a novice because I'm a novice in Meteorology too. Subscribe to his channel and give him some attention:
For those who are so concerned with Fukushima fallout radiation and are hiding under your shower-caps in California with G4T you need to watch this video. Notice how many things in our natural environment are measuring radioactivity: