At Kodai Sangyo, we had been conducting daily measurements of the surrounding environment in order to ensure an amenable working environment and to prevent contamination of our products. However, news reports of cesium being detected in firewood and sawdust has prompted us to decide to take the step of measuring our products for contamination, and releasing this data to the public.
Measurements of environmental radioactivity of our products
The accident at Fukushima Daiichi power plant resulted in food contamination as well as cesium being detected in the firewood from Iwate used for Kyoto’s Daimonji bonfires. As a consequence, we have received many inquiries regarding the radioactive contamination of our products.
Given that our former measuring equipment only measured beta radiation, we therefore decided to purchase equipment that can also measure gamma radiation.
- Units: cpm (counts per minute), Bq (Becquerel)
- Measuring instrument: Thermo Scientific “Rad Eye B20-ER” Multi-Purpose Survey Meters, Made in Germany
- At present 100,000 cpm or above is considered the standard for contamination of humans and vehicles, etc. 100,000 cpm is equivalent to 1666.7 Bq.
- Additionally, the Forestry Agency of Japan (Rin’yacho) shipping standards are up to 100,000 cpm.
Evidence of safety
Generally, the wood that we use as timber does not absorb radioactive material that is dispersed in the atmosphere, nor does dirt and dust containing radioactive material tend to adhere to this easily. (From the website of the Forestry Agency [Japanese]）
We use domestically produced cypress, and this timber is all sourced from the Yamizo-san mountain range spanning Ibaraki, Tochigi, and Fukushima Prefectures, which is further than 80 km from the stricken Fukushima Dai’ichi Nuclear Power Plant. Trees have their bark removed before using used as timber, and after being dried, are processed by surface planing.
Given the above, please rest assured that in accordance with Forestry Agency guidelines, Kodai Sangyo products require neither decontamination nor special handling restrictions because of radioactive contamination, and thus can be used with confidence.
For your reference, the website below contains information on regulations on imported products of other countries, radiation inspections, and issuance of certificates for export products. (From the website of Japan External Trade Organization [Japanese])