A steady stream of customers in search of radiation dosimeters filled a store tucked away in an alley in Tokyo’s Akihabara district on Nov. 19.
A steady stream of customers in search of radiation dosimeters filled a store tucked away in an alley in Tokyo’s Akihabara district on Nov. 19.
A year ago, many of the Toyo Keisokuki store’s new clients would not have known what a dosimeter was, but in Japan since the accidents at the Fukushima No. 1 nuclear power plant, the meters are rapidly becoming a hot item.
More than 10 types of dosimeters line the shelves at Toyo Keisokuki, with price tags ranging from 30,000 yen to 200,000 yen (about $400 to $2,667).
The store says it has sold several hundred dosimeters since the disaster, often to parents or grandparents concerned about the threat of radiation to their children or grandchildren. Sales are up 10 times on previous years, when most buyers were engineers.
One of the new customers, Tsunehito Wake, 38, runs a firm in Tokyo's Suginami Ward and has three young children aged between 1 and 5.
Concerned about the effects of radiation from the Fukushima disaster, he evacuated his children to Shikoku island in western Japan in March and is still concerned about contamination at his Tokyo-area home.
He brought in an expert to measure radiation levels in his garden, but was visiting Toyo Keisokuki on Nov. 19 to get his own dosimeter. He said he had searched for dosimeters on the Internet, but needed advice to work out which one to get.
"If the dosimeter shows a high radiation level that makes you anxious, you should report it to the local government," a clerk told him.
Wake eventually bought a Russian-made dosimeter with a manual written in Japanese and priced between 30,000 yen and 40,000 yen.
Masami Ishibashi, an assistant at the store, said she always asks customers what they want to measure before selling anything.
Most dosimeters measure levels of radiation issued by radioactive materials in the air or accumulated on surfaces, but those meters cannot measure radioactive materials contained in food, a process which requires large and expensive equipment.
There are also significant differences between meters designed to measure environmental radiation, despite often having a similar outward appearance.
Geiger-Muller counters, for example, measure overall rays emitted from radioactive materials such as beta rays and gamma rays. Beta rays are only detectable near contaminated objects, making the counters well suited to checking contamination levels on surfaces where radioactive materials might have accumulated.
Scintillation counters, on the other hand, are favored by many local governments looking to detect threats to human health because they measure gamma rays, which have a longer range than beta rays and can harm the human body.
A whole range of other dosimeters, including semiconductor-type meters, are also available.
"Choosing equipment suitable for your purposes is the first step toward accurate measurement," Ishibashi said.