Slag Melting for Radioactive Waste
Development of process induction slag melting of radioactive waste.
Tech Area / Field
- ENV-RWT/Radioactive Waste Treatment/Environment
8 Project completed
Senior Project Manager
All-Russian Scientific Research Institute of Non-Organic Materials named after A. Bochvar, Russia, Moscow
- NPTz Inductor, Russia, Moscow
- Power Reactor and Nuclear Fuel Development Corporation (PNC), Japan, Tokyo
Project summaryWhen processing spent fuel assemblies (SFA) various nuclear reactors on each ton of processed nuclear fuel 330 kg of high level metal wastes (HLMW) containing, except, for breakage of hull full elements from zirkonium alloys or stainless steel, various details SFA is formed. The metal wastes are a-, b-, g-radiation materials, theirs radioactivity is stipulated of reactor, exposure, as well as presence of uranium and fission product, which are diffusing in hull fuel elements from fuel during work of nuclear reactor. The storage HLMW is executed in special attended storages (HLMW from zirconium alloys are mixed with alumina), which is rather difficult and expensive. The processing and disposal HLMW can be to give the positive effect in several directions:
- reduction of volumes of storages or repositories;
- transfer of part HLMW (from stainless steel) from category high level in middle- and low-level and, as the consequence, simplification and price reduction of their storage and disposal;
- increase of ecological safety at storage and disposal.
From the varied of the following offered methods of processing HLMW: two-step pressing (USA, Germany, Japan), concreting (Germany), oxidation hull wastes and then inclusion of them in silicate or alumosilicate connection (USA, France) is the most practical value method HLMW in furnace with cold crucible. This method is in details investigated in France on hull fuel elements from zirconium alloys and stainless steel and the opportunity no only of reduction in of 6 time volume wastes but their clearing on 2-3 order from series of long-lived radionuclides with receptions monolithic ingots of diameter to 200 mm and length to 1 m, suitable for disposal is shown. The experience of France and preliminary researches, conducted in ARSRIIM and ARSRIETE shows the possibility induction-slag melting of all types HLMW in furnaces with cold crucible and reception ingots of diameter to 500 mm and length to 2,5 m.
The aim of given project is the research of technology and checking on imitation fuel hull materials experimental and demonstration equipment for induction-slag melting: cut hull fuel elements from zirkonium alloys and stainless steel; end pieces of SFA from stainless steel.
Main technological tasks of project:
- determination of optimum conditions (technological, electrotechnical etc.) processes smelting of details SFA from zirconium alloys and stainless steel in induction melting with cold crucible as well as forming ingots of various diameter and length;
- valuation of degree of clearing HLMW from TRU and FP at them induction-slag melting with various fluxes;
- research of technology of processing of forming secondary wastes (slag, gas phase);
- research of structure and properties of intermediate and final products of processing HLMW;
- development of recommendations for apparatus -technological scheme of treatment various HLMW.
While realization this project the technology will be developed and on simulators HLMW the experimental equipment for preparation to disposal HLMW their clearing and reliable localization remaining long-lived radionuclides (with period half-time more than 104 years) in metal matrixes, speed of leaching of radionuclides from which less 10-7 g/cm2ґday will be checked. At induction-slag melting of metal wastes the clearing of them from TRU and FP with factor of clearing more 500 and reception ingots of given weight and geometry, suitable for disposal is expected. At realization of developed technology in industry the reduction in of 6 time (volume HLMW and as the result of this, reduction of volumes of expensive storehouses and repositories, as well as maintenance of ecological safety and economic efficiency of disposal perse HLMW is expected).