Thorium determination in intercomparison samples and in some Romanian building materials by gamma ray spectrometry

Our plain-English summary of Thorium determination in intercomparison samples and in some Romanian building materials by gamma ray spectrometry, by A. Pantelica, I.I. Georgescu, M.D. Murariu-Magureanu, et al (Radiation Protection Dosimetry, 2001).

The study

• Authors: A. Pantelica, I.I. Georgescu, M.D. Murariu-Magureanu, I. Margaritescu, E. Cincu
• Journal: Radiation Protection Dosimetry
• Published: 2001;97(2):187-91
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Thorium content in zircon sand, thorium ore and a thorium liquid sample (EU Laboratories Network Intercomparison), as well as in some Romanian building materials: sand, wood, tufa, asbestos-cement. cement mill dust, coal fly ash, bricks, and tile (28 samples) was deterimined by gamma ray spectrometry. For the building materials, 226Ra, 40K and 137Cs specific activities were also measured. The results were compared with the Romanian legal norms concerning the highest admissible levels for 232Th, 226Ra. and 40K radioactivity. and to Th, U, and K concentration values previously determined in our laboratory on similar types of samples.

In plain English

This laboratory study measured radioactivity in mineral samples by gamma ray spectrometry. It did not study asbestos fibers or anyone's health. The authors first analysed three test samples (zircon sand, thorium ore and a thorium nitrate liquid) prepared by the UK National Physical Laboratory for a European intercomparison exercise. Their thorium-232 results closely matched the reference values, with ratios of 1.045, 0.99 and 0.97. They then measured thorium-232, radium-226, potassium-40 and caesium-137 in 28 building material samples from factories in southern Romania, most collected in summer 1999. Three of these were asbestos-cement samples, whose thorium-232 levels were 10.8 to 13.5 Bq per kg. Compared with Romanian legal limits, thorium-232 was about 1.3 to 2 times higher in two red brick samples. Thorium-232, radium-226 and potassium-40 were higher in almost all tile samples. The article gave no legal limits for asbestos-cement. The authors concluded that gamma ray spectrometry can be used to analyse thorium in liquid and solid mineral samples, provided radioactive equilibrium with its decay products is established.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory measurement study (gamma ray spectrometry of intercomparison test samples and building material samples)
• Who was studied: Three intercomparison test samples (zircon sand, thorium ore, thorium nitrate liquid) prepared by the UK National Physical Laboratory, plus 28 building material samples (red brick, autoclaved cellular concrete brick, tile, cement mill dust, asbestos-cement, coal fly ash, sand, tufa, wood) from factories in the southern half of Romania. Most were collected in summer 1999; cement mill dust from Hoghiz (April 1994) and Fieni (May 1995) and coal fly ash from Deva (March 1995) were collected earlier.
• Exposure: Natural radioactivity (thorium-232 via its decay products, radium-226, potassium-40) and caesium-137 in building materials, including three asbestos-cement samples (Horezu, Targu Jiu, Craiova). No asbestos fiber type or fiber exposure was studied.
• Main results:
  • Intercomparison samples: thorium-232 results agreed with the National Physical Laboratory target values. Ratios of measured to target value were 1.045 for zircon sand (576 ± 14 vs 551 ± 21 Bq per kg), 0.99 for thorium ore (2472 ± 47 vs 2494 ± 32 Bq per kg) and 0.97 for the thorium nitrate solution (10435 ± 294 vs 10716 ± 102 Bq per kg).
  • Compared with Romanian legal norms, values about 1.3 to 2 times higher were found for thorium-232 in two of the red brick samples, and for thorium-232, radium-226 and potassium-40 in almost all tile samples.
  • The Romanian accepted levels cited were 53.3 Bq per kg for thorium-232, 100 Bq per kg for radium-226 and 832 Bq per kg for potassium-40 in red brick, and 32.2, 32.6 and 466 Bq per kg respectively in tile.
  • Asbestos-cement samples: thorium-232 was 10.8 ± 1.6 Bq per kg (Horezu), 10.8 ± 0.9 (Targu Jiu) and 13.5 ± 1.4 (Craiova). The corresponding thorium contents were 2.7 ± 0.4, 2.7 ± 0.2 and 3.3 ± 0.3 mg per kg.
  • Asbestos-cement samples: radium-226 was 7.6 ± 1.8 (Horezu), 4.3 ± 1.1 (Targu Jiu) and 8.9 ± 1.2 (Craiova) Bq per kg. Potassium-40 was 46.5 ± 9.3, 46.6 ± 6.5 and 56.6 ± 9.0 Bq per kg. Caesium-137 was 7.6 ± 0.5, 0.9 ± 0.5 and 7.7 ± 1.0 Bq per kg.
  • Thorium, uranium and potassium concentrations in the building materials were similar to values the laboratory had previously obtained by other methods in cement, a cold compacted brick, coal fly ash and wood.
• The authors' conclusion: The authors concluded that gamma ray spectrometry could be used successfully to analyse thorium in liquid and solid mineral samples, provided radioactive equilibrium between thorium-232 and its decay products is established. They added that it also allows uranium and potassium analysis in building materials.
• Limitations the authors state:
  • Thorium-232 was calculated from its decay products on the assumption of radioactive equilibrium in the decay chain. The authors' conclusion is conditional on that equilibrium being established.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Cement.

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