US EPA

1432162 

Journal Article 

Radioactivity in Zirconium Oxide Powders Used in Industrial Applications 

Lischinsky, J; Vigliani, MA; Allard, DJ 

1991 

Yes 

Health Physics
ISSN: 0017-9078
EISSN: 1538-5159 

NIOSH/00201475 

60 

6 

859-862 

2032840 

10.1097/00004032-199106000-00009 

WOS:A1991FN60400012 

Issues pertaining to natural radioactivity in zirconium-oxide (1314234) powders used for industrial applications were discussed. The discovery of natural radioactivity in zirconium-oxide powders raised a number of concerns about the adequacy and applicability of existing regulatory guidelines. Regulatory issues were discussed. Gamma ray spectroscopic analysis of two samples of the powders from unopened lots revealed that they contained 0.053% (by weight) radioactive source material consisting primarily of uranium-238 (7440611) and smaller amounts of uranium-235 (15117961) and thorium-232 (7440291) (Th-232). This level of radioactivity placed the zirconium-oxide powders marginally above the 0.05% licensing threshold. Implications for the legally mandated decontamination of materials contaminated with natural and depleted uranium and natural thorium were considered. External exposures from concentrations of uranium and its daughters present in the zirconium-oxide powders appeared to be negligible due to the low effective dose rate. The principal radiological concern was the possibility that the zirconium-oxide powder could become suspended in air as a dust at a concentration exceeding the OSHA respirable zirconium compound limit. Calculations of potential airborne concentrations showed that radiation doses due to uranium or Th-232 in the zirconium-oxide powder amount to only 15 and 6% of the Nuclear Regulatory Commission maximum permissible limit of 0.19 becquerel per cubic meter. The authors conclude that some zirconium-oxide powders used for industrial applications contain fairly significant amounts of natural uranium. This radioactivity does not appear to be well documented and may not be considered in industrial safety programs. Working with the zirconium-oxide powder should not present a serious radiological hazard if rigid industrial hygiene practices are observed and the material is treated properly as a zirconium compound. 

DCN-201346; Zirconium alloys; Radioactive metals; Mathematical models; Risk analysis; Radionuclides; Radiation decontamination; Industrial safety; Standards; Legislation; Radiation hazards