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Title: Criteria determining the selection of slags for the melt decontamination of radioactively contaminated stainless steel by electroslag remelting

Electroslag remelting is an excellent process choice for the melt decontamination of radioactively contaminated metals. ESR furnaces are easily enclosed and do not make use of refractories which could complicate thermochemical interactions between molten metal and slag. A variety of cleaning mechanisms are active during melting; radionuclides may be partitioned to the slag by means of thermochemical reaction, electrochemical reaction, or mechanical entrapment. At the completion of melting, the slag is removed from the furnace in solid form. The electroslag process as a whole is greatly affected by the chemical and physical properties of the slag used. When used as a melt decontamination scheme, the ESR process may be optimized by selection of the slag. In this research, stainless steel bars were coated with non-radioactive surrogate elements in order to simulate surface contamination. These bars were electroslag remelted using slags of various chemistries. The slags investigated were ternary mixtures of calcium fluoride, calcium oxide, and alumina. The final chemistries of the stainless steel ingots were compared with those predicted by the use of a Free Energy Minimization Modeling technique. Modeling also provided insight into the chemical mechanisms by which certain elements are captured by a slag. Slag selection was alsomore » shown to have an impact on the electrical efficiency of the process as well as the surface quality of the ingots produced.« less
Authors:
; ;  [1] ;  [2]
  1. Sandia National Labs., Albuquerque, NM (United States)
  2. Oregon Graduate Inst. of Science and Technology, Beaverton, OR (United States)
Publication Date:
OSTI Identifier:
453468
Report Number(s):
SAND--97-0601C; CONF-970232--6
ON: DE97004131; TRN: 97:006771
DOE Contract Number:
AC04-94AL85000
Resource Type:
Conference
Resource Relation:
Conference: International symposium on liquid metal processing and casting, Santa Fe, NM (United States), Feb 1997; Other Information: PBD: [1997]
Research Org:
Sandia National Labs., Albuquerque, NM (United States)
Sponsoring Org:
USDOE, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
05 NUCLEAR FUELS; STAINLESS STEEL-304L; RADIOACTIVE WASTE PROCESSING; DECONTAMINATION; SLAGS; ELECTRIC FURNACES; MATHEMATICAL MODELS; CALCIUM FLUORIDES; CALCIUM OXIDES; ALUMINIUM OXIDES; SCRAP METALS; SURFACE CLEANING; PHASE DIAGRAMS