Mystery: Radioactive black substance reported 25km from Fukushima — Latest measurement over 95 µSv/h — Strong alpha emitter detected (PHOTOS)

Published: February 12th, 2012 at 9:22 pm ET
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SOURCE: ameba.jp

Paraphrased translation provided by N.K., a concerned citizen in Japan

What follows is a summary of a series blog posts about mysterious radioactive black materials found in and around Minami-Soma City, Fukushima Prefecture, about 25km from the plant.

Black materials looking like sand or powder were found in the Haramachi-ku area of Minami-Soma City.

A similar substance was also found in nearby Soma City.

The materials can reportedly be found many places in Minami-Soma city and Soma city areas.

Here are several recent measurements:

Jan. 27: Measured values in Haramachi-ku using the Inspector +

  • 901 cpm: gamma ray only, with WT Plate, 1cm above GND
  • 13,380 cpm: gamma + beta + alpha, without WTP, 1cm above GND
  • 10,330 cpm: gamma + beta + alpha, with XEROX paper, 1cm above GND

This means that XEROX paper cuts off 3,050 cpm alpha-ray, so the quite strong alpha-ray is radiated from the materials.

Feb. 4: The materials could not be found at Fukushima City
, 60km from the plant. Only gamma-ray were strong.

Feb. 6: Normal sand in the area mainly contains Cs134 and Cs137

  • Gamma-ray: 959 cpm
  • Gamma + beta + alpha: 2,146 cpm

Feb. 6: Black material in sand

  • gamma-ray: 3,274 cpm
  • gamma + beta + alpha: 18,370 cpm

Radiation of the black materials were very strong when compared to the normal-colored sand. The materials have unbelievable beta + alpha.

Feb. 9: Piece of paper cuts shields 7,230 cpm

  • gamma + beta + alpha: 31,680 cpm, without the paper
  • gamma + beta + alpha: 24,450 cpm, with the paper

TERRA MKS-05 measures only gamma and beta-ray, XEROX paper did not make much difference

  • 11.53 micro S/h: gamma-ray only, without paper
  • 17.56 micro S/h: gamma + beta, without paper
  • 16.98 micro S/h: gamma + beta, with paper

Feb. 11: Latest measurement of the black materials

95.40 micro S/h: gamma + beta + alpha

See more photos by following the links above

Published: February 12th, 2012 at 9:22 pm ET
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19 comments

19 comments to Mystery: Radioactive black substance reported 25km from Fukushima — Latest measurement over 95 µSv/h — Strong alpha emitter detected (PHOTOS)