More low-cost radiation detectors hit the marker for worried consumers


Older version of the S.T. Corporation's Geiger Counter

TOKYO (majirox news) — Geiger counters and radiation detectors (dosimeters) are popular sellers these days. Many Japanese are concerned that the winds are carrying radiative material from Fukushima Daiichi nuclear power plant and are seeking out Geiger counters.

Due to the extremely high demand of the detectors and customers being told that they may have to wait weeks to receive their orders, S.T. Corporation decided to mass produce them.

S.T., which sells household products, previously only sold them in the Fukushima region.

The company will now introduce new models and make them available to consumers across Japan in February 2012.

The new detectors cost 7,900 yen ($101), takes two minutes to measure radiation levels and weighs only 60 grams. The old models, which the company released in October, costs 9,800 yen ($126), took five minutes to measure radiation levels and weighed 110 grams.

“The new radiation detectors handles a lot better,” said a company spokesman today.

Experts say making an accurate Geiger counter is fairly expensive.

“I am extremely skeptical that a 7,000 yen Geiger counter is useful,” says Tomo Fujita. “Unless there is a Geiger-Mueller tube in a Geiger counter it’s not really a Geiger counter.”

He added the size of the Geiger counter matters — the larger the counter is (within limits of being handheld) the larger the sensor inside of it can be, or in the case of the Ukrainians, multiple sensors can be put in.”

There are small dosimeters that give accurate readings, for example one made in the United States combines scintillation with diodes to read both high and low radiation. But it takes between 20 to 40 minutes to produce a reading.

“The Geiger counter field is also overrun with con men, and not a few of the Japanese-made Geiger counters are condemned by Japanese experts as being worthless,” Fujita said.

Pieter Franken, senior visiting researcher at Keio University and co-founder of, agrees.

“Instead people can see radiation levels in their street on Safecast for free,” he says. “The devices sold cannot be used to check food or surface. They are useless to help in decontamination. Though technically the vendor will not make these claims, consumers don’t understand it and will wave it at food and surface, thinking it’s safe. Two minutes is extremely slow. Proper equipment gives reason in a few seconds, so it quickly allows you to find a hotspot.”

He added, people need a device to quickly scan the environment for hotspots and scan measure surface contamination (with sensitivity for beta, not only gamma) to confirm if a surface is radioactive or not, which can’t be done with a gamma only survey meter.

However, Kyoko Koyama, a housewife in Tokyo, said she will buy one of S.T. Corp’s detectors. “I want to be prepared and don’t have faith that I will get the real information on radiation levels. Besides, I can only afford this one.”

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