Inadvertent Melting of Radioactive Sources in BOF or EAF : Distribution of Nuclides, Monitoring, Prevention
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概要
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This report lists the relevant nuclides presently or formerly in use as radiation sources and gives an account of their expected distribution between steel melt, slag, dust and off-gas upon inadvertent meltdown. Three groups of nuclides are identified, namely (a) strong γ-emitters (Co 60, Kr 85, Cs 137, Ir 192), (b) weak γ-emitters (Ra 226, Am 241), and (c) β- and α-emitters (Ni 63, Sr 90, Pm 147, Pu 238/239, and Cm 244). Equilibrium distributions based on thermodynamic calculations and experimental investigations are presented.Combining the equilibrium partition ratios with process-specific effects leads to realistic distribution ratios: The steel melt is expected to contain about 98% of the radioactive Co, Ni, and Ir, while the dust will contain practically all the Cs and about 1% of all the other nuclides except Kr which should completely pass to the off-gas. The slag is expected to contain about 99% of the nuclides Sr, Pm, Ra, Am, Pu and Cm, and about 1% of Co, Ni and Ir dissolved in the suspended metal granules.The strongly γ-emitting nuclides can be, and are increasingly, monitored quasi on-line on steel samples taken in the meltshop and, with respect to Cs, in the baghouse. The respective equipment operates reliably and efficiently. An on-line detection of weak γ-emitters and of α- and β-emitters is technically not possible at present. The steelworks can minimize the risks connected to the inadvertent melt-down of a radioactive γ-source by introducing three consecutive steps of measures: Prevention by inspection of incoming materials; Inhouse Scrap Monitoring by inspection during transport, and finally Product Control by monitoring of steel samples and in the bag-house.
- 2005-02-15
著者
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NEUSCHUTZ D.
Materials Chemistry, Rheinisch-Westfalische Technische Hochschule (RWTH) Aachen
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SPIRIN D.
Materials Chemistry, Rheinisch-Westfalische Technische Hochschule (RWTH) Aachen
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QUADE U.
Siempelkamp Nukleartechnik (SNT)
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MEIER-KORTWIG J.
Laboratory of Metallurgy, Helsinki University of Technology (HUT)
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HOLAPPA L.
Laboratory of Metallurgy, Helsinki University of Technology (HUT)
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HAMALAINEN M.
Laboratory of Metallurgy, Helsinki University of Technology (HUT)
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LOZANO M.
Acerinox, S.A.
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BONANY M.
Acerinox, S.A.
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Lozano M.
Acerinox S.a.
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Holappa L.
Laboratory Of Metallurgy Helsinki University Of Technology (hut)
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Bonany M.
Acerinox S.a.
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Spirin D.
Materials Chemistry Rheinisch-westfalische Technische Hochschule (rwth) Aachen
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Neuschutz D.
Materials Chemistry Rheinisch-westfalische Technische Hochschule (rwth) Aachen
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Hamalainen M.
Laboratory Of Metallurgy Helsinki University Of Technology (hut)
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Meier-kortwig J.
Laboratory Of Metallurgy Helsinki University Of Technology (hut)