dosimeters

続編。
News Navigator: What kinds of dosimeters are out there, and can I buy one?

The Mainichi answers some common questions readers may have about radiation measurement equipment, which has been in high demand following the nuclear disaster at the Fukushima No. 1 nuclear plant.

Question: Relatively high levels of radiation have been detected at one location after another in the Tokyo metropolitan area since early October, haven't they?

Answer: Radioactive strontium measuring 195 becquerels per kilogram was detected in sediment collected from the rooftop of a condominium in Yokohama's Kohoku Ward after its residents commissioned a private laboratory to analyze the material. Residents in Tokyo's Setagaya Ward also detected high levels of radiation using a hand dosimeter, but it later turned out that bottled radium stored under the floor of a nearby house had been responsible for the radiation.

Q: So more and more citizens are measuring radiation on their own. What is a radiation meter like in the first place?

A: In order to measure external radiation doses, a small dosimeter that can be attached to your chest or carried in a pocket will do. Such gadgets are aimed at gauging radiation doses per hour or accumulated doses, and products in the 20,000 to 60,000 yen range are hot sellers these days.

If you want to measure radiation emissions in a given amount of time at a certain location, you can use a survey meter. Since the equipment is more sensitive to radiation than dosimeters, it comes in at a rather pricy 300,000 to 500,000 yen per unit, and is mainly purchased by local governments and companies.

Q: Are many private individuals snapping up dosimeters?

意味合いは？しょうへいさん

A: There had apparently been a marked uptick in private individuals buying dosimeters at electronics shops and Internet retailers. According to Hitachi-Aloka Medical, one of Japan's major dosimeter manufacturers, the company used to produce 400 dosimeters a month before the start of the nuclear crisis on March 11, but monthly production volume has jumped to some 10,000 since.

てらかどさん

Q: So are the devices scarce?

A: One dosimeter wholesaler says it can ship devices in one or two business days. Hitachi-Aloka Medical, meantime, says survey meters may take time to reach customers as some products are back-ordered, despite a production increase to some 1,000 units a month -- more than 10 times more than normal.

たけいしさん

Q: What should we keep in mind when purchasing a dosimeter?

A: The National Consumer Affairs Center of Japan (NCAC) has purchased and tested nine out of the top 10 selling dosimeters available online, all priced at less than 100,000 yen per unit, and all of them turned out to be inaccurate. All the nine products were made in China.

Between March 11 and Sept. 30, the NCAC received 187 consumer consultations about the quality and functions of dosimeters. Consumers will get confused unless they use accurate measuring devices. It is important to purchase dosimeters in accordance with the intended use after examining product manuals and performance test results. (Answers by Taichi Yamamoto, City News Department)

(Mainichi Japan) October 22, 2011