Fukushima prefecture plans on checking for radiation contamination in their rice with radiation detectors. However, food and water require laboratory analysis to detect radioisotopes.
Radiation detectors are insufficient for checking food or water for their safety. See this article in Bloomberg dated 4/2011
Geiger Counters Unlikely to Detect Radiation in Food, Water http://www.bloomberg.com/news/2011-04-12/geiger-counters-to-find-radiation-in-meals-may-be-meaningless-.html
[Excerpted] Geiger counters are probably ineffective for consumers in detecting hazardous levels of radiation in food and water at home, scientists, professors and device makers said.
Large samples should be tested in laboratory-like settings to obtain results, said Joseph Rotunda, who heads the radiation measurement division at toolmaker Thermo Fisher Scientific Inc. Determining whether food, water or milk is safe also requires expert knowledge and more sophisticated equipment than the typical devices sold online, said Atsushi Katayama, a member of the Japan Society for Analytical Chemistry.
Majia here: Radiation detectors may detect very, very highly contaminated food, but are insufficient for detecting most levels of contamination likely to occur.
So why is Fukushima Prefecture planning on checking the safety of Fukushima rice with radiation detectors?
Fukushima rice put on sale after radiation test. NHK 8/28/2012 http://www3.nhk.or.jp/daily/english/20120828_26.html
Radioactivity levels exceeding the government standard were detected in rice harvested in the prefecture last year following the nuclear disaster at the Fukushima Daiichi plant.
The prefecture is conducting mandatory tests on all rice before shipment this year....
...Fukushima prefecture plans to use 192 radiation detectors to check all 360,000 tons of rice that will be harvested this season....