Work recently published in the journal Chemosphere has documented the presence of large amounts of highly radioactive, poorly soluble cesium rich micro-particles (CsMPs) in an abandoned school building close to the Fukushima Daiichi Nuclear Power Plant (FDNPP).
The microparticles penetrated the building during the FDNPP nuclear accident of March 2011. They could pose a threat to human health if inhaled. The study shows that indoor CsMPs should be considered in safety assessments and in building clean-up efforts.
[...] In recent years, the team have shown that a significant amount of cesium rich microparticles (CsMPs) were released from the damaged FDNPP reactors. These particles have a radius of only a few micrometers, and they are mainly composed of Si-glass, Fe, [and] Zn. The radioactive Cs content of the CsMPs is much higher than any other form of Cs-labeled fallout released from the damaged FDNPP reactor units 1-3.
The team has previously shown that the particles were likely produced temporarily during the FDNPP meltdown events, when molten fuel in each reactor unit escaped primary containment and impacted the underlying concrete base. To date, work on CsMP containing samples has mainly concentrated on CsMPs found outdoors. The CsMPs were entrained in air and carried into the environment from the damaged reactors, becoming widely distributed in the FDNPP exclusion zone.
Recent work by several scientific teams has also shown that CsMP contaminated air masses that passed over the Tokyo region during March 2011. This information, coupled with findings that CsMPs are poorly soluble, has led to questions over potential health risks posed by internal radiation exposure if CsMPs are inhaled. Utsunomiya states that "given the small size of the particles (generally The Cs radioactivity of the dust on the school's floors ranged from 340—4040 Bq/m2 (134+137Cs activity decay-corrected to March 15, 2011. This corresponds to 125—1490 Bq/m2 in 2023), with 4.5—38.9% of that radioactivity coming from the CsMPs.
The highest amount of CsMPs were found near to the school's entrance (up to 2481 particles per m2), while significant (but lower) amounts of CsMPs were found on the second floor (up to 1273 particles per m2). This shows penetration of the tiny fallout particles deep into the building. Interestingly, the CsMP numbers and the proportion of Cs radioactivity attributed to CsMPs in nearby outdoor samples were much lower (23–63 particles/g of dust or soil and 1.14–1.61% or total Cs radioactivity, respectively).
[...] Professor Bernd Grambow, a co-investigator from the University of Nantes added, "Any decontamination strategy needs to acknowledge that in close vicinity to the power plant, large differences in contamination levels may be encountered and that both ionic and particle bound Cs needs to be analyzed and removed, with the latter being particularly dangerous to cleaning workers."
Professor Rodney C. Ewing of Stanford University further added, "This study is latest of an extended series of papers that deal with the composition, characteristics, formation, and number of CsMPs. The groundbreaking aspect of these works is the combined application of multiple advanced techniques e.g., the team's autoradiography methods, high-resolution electron microscopy, and isotopic analysis. The atomic-scale resolution of these studies provides a model for future studies of environmental contamination."
Journal Reference:
Occurrence of radioactive cesium-rich micro-particles (CsMPs) in a school building located 2.8 km south-west of the Fukushima Daiichi Nuclear Power Plant, Kazuki Fueda, Tatsuki Komiya, Kenta Minomo et al. (DOI: 10.1016/j.chemosphere.2023.138566)
(Score: 1) by pTamok on Tuesday May 30 2023, @11:23AM (3 children)
The dose from the body's natural complement of potassium 40 is roughly 5000 Bq (1 Bq is one decay per second).
See also Banana Equivalent Dose [wikipedia.org]
(Score: 0) by Anonymous Coward on Tuesday May 30 2023, @02:31PM (2 children)
Can you elaborate on this comparison? There are different units here, Bq/m2 and Bq so it would appear that an area is required, along with some idea of how many particles cleaners might expect to inhale when stirring up many meter^2 of dust.
(Score: 3, Interesting) by pTamok on Tuesday May 30 2023, @02:59PM (1 child)
One bequerel is one radioactive decay per second. It's not used very much, as the kind of radioactivity and the chemical state of the radioactive atoms affects the effect radioactive things have on the body. For an adjusted 'radioactivity' measure that takes into account some of these things, you need to use [wikipedia.org]sieverts [wikipedia.org], which are a whole lot more complicated.
The whole body dose of radiation due solely to the fact that you naturally have radioactive Potassium 40 blended in the the non-radioactive Potassium translates to about 5000 decays per second in the volume of your body.
The Bq/square meter is the number of decays per second seen over a square meter of area.
The Wiki article gives some perspective
(Score: 0) by Anonymous Coward on Tuesday May 30 2023, @06:48PM
Thanks!!