Incineration Of Radioactive Waste Research Articles

Radiation Safety for Incineration of Radioactive Waste Contaminated by Cesium

Problems in the treatment of radioactive waste contaminated by cesium nuclides are considered in the paper. Chornobyl experience in the management of contaminated soil and contaminated forests is analyzed in relation to the accident at Fukushima-1. The minimization of release of cesium aerosols into atmosphere is very important. Radiation influence of inhaling atmosphere aerosols polluted by cesium has damage effect for humans. The research focuses on the treatment of forests contaminated by big volumes of cesium. One of the most important technologies is a pyro-gasification incineration with chemical reactions of cesium paying attention to gas purification problems. Requirements for process, physical and chemical properties of treatment of radioactive waste based on the dry pyro-gasification incineration facilities are considered in the paper together with the discussion of details related to incineration facilities. General similarities and discrepancies in the environmental pollution caused by the accidents at Chornobyl NPP and Fukushima-1 NPP in Japan are analyzed.

Report on intermediate results of the IAEA CRP on ‘Studies of advanced reactor technology options for effective incineration of radioactive waste’

In 2003 the IAEA has initiated a Coordinated Research Project (CRP) on “Studies of Advanced Reactor Technology Options for Effective Incineration of Radioactive Waste”. Major intermediate results have been obtained and will be reported here. The overall objective of the CRP, performed within the framework of IAEA’s Nuclear Energy’s Department Technical Working Group on Fast Reactors, is to increase the capability of Member States in developing and applying advanced technologies in the area of long-lived radioactive waste utilization and transmutation. Sixteen institutions from 12 member states and one international organization participated in this CRP. The CRP concentrated on the assessment of the dynamic behaviour of various transmutation systems. The reactor systems investigated comprise critical reactors, subcritical accelerator driven systems with heavy liquid metal and gas cooling, critical molten salt systems and hybride fusion/fission systems. Both fertile and fertile-free fuel options have been investigated. For a deep assessment of the transient and safety behaviour, the analytical capabilities have to be qualified. A major effort of the CRP consisted in the benchmarking of steady state core configurations and performing transient/accident simulations. For a general assessment and comparison, the safety coefficients were determined for the individual systems. In a second step transient analyses were performed which reflected the generic behaviour of the various reactors types. In addition the transmutation potential, burn-up behaviour and decay heat of minor actinide bearing fuels were investigated.

Radioactive Waste Incineration-Ash Pellets Sintered with Borosilicate Glass

In Japan, low-level radioactive wastes discarded by research institutions and hospitals are packed into containers and stored. Volume reduction by incineration and compression processing are sometimes attempted; alternatively, the wastes are left in an unprocessed state because neither landfill sites nor disposal methods have been established. Especially, low-level radioactive waste incineration ash presents great problems of security, safety, and stability in inventory location. A safe and appropriate disposal processing method is desired because the bulk density of ash is low; the ash is also easily dispersed. Volume reduction and stabilization for low-level radioactive waste incineration ash were verified for low-temperature sintering method using glass bottle cullet. The proposed method was useful for easy treatment of low-level radioactive waste incineration ash. This report describes the difference between soda lime glass (cullet) and borosilicate glass for the RI ash sintering, and characteristics of RI volatilization and elution from the sintered radioactive waste pellets. The borosilicate glass is used for glass melt solidification of high-level radioactive waste.

Heat treatment of chlorinated waste in a rotating kiln: Problems with intermediate reaction products and solutions applied

At the CEA, the incineration of radioactive wastes is carried out thanks to the IRIS process involving a oxidizing pyrolysis step performed with a rotary kiln. If the running of the process is very satisfactory for processing waste of a given composition, it appears that the behavior of the kiln may diverge when the composition of the waste change. Through the example of wastes containing a large amount of PVC and thanks to a very simple modelling of the heating of the kiln, it has been demonstrated that the deposits are involved in overheating of the pyrolysis kiln. Fundamental investigation carried out about the thermal degradation of PVC and cellulose have shown that the formation of intermediate PVC decomposition compounds together with the residues coming from the decomposition of the cellulose could be responsible of the large amount of deposits. In order to avoid the malfunctions it has been proposed to revise the furnace operating parameters by specifying a waste feed sequence that ensure a relaxation period to the furnace. By this way, the running of the facility shows a very good stability with a very thin temperature oscillation that can easily be explained by a thermal modelling of the kiln.

廃棄物焼却灰の減容化・安定化方法の開発

The low-level radioactive waste generated from research institutions and hospitals etc. is packed into a container and is kept. The volume reduction state by incineration and the compression processing or the unprocessed state because neither landfill sites nor disposal methods have been fixed. Especially, because the bulk density is low, and it is easy to disperse, the low-level radioactive waste incineration ash incinerated for the volume reduction has a big issue problem in security, safety, stability in the inventory location. A safe and appropriate disposal processing method is desired. When the low temperature sintering method in the use of the glass bottle cullet was examined, it was verified that volume reduction and stabilization of low-level radioactive waste incineration ash. The proposed method is useful for the easy treatment of the low-level radioactive waste incineration ash.

Leaching Behavior and Characteristics of Glass Components and Surrogate Nuclides in Radioactive Vitrified Waste Forms

Several vitrified waste forms were fabricated and characterized, which contain simulated radioactive waste incineration ash, and a long-term leaching test was conducted by an ISO method for 820 days to assess the chemical durability of vitrified waste forms. Two semi-empirical mechanism models were applied to find out the dominant leaching mechanism of glass elements. For glass elements, dissolution associated with diffusion was the dominant leaching mechanism and leaching characteristics also depend upon solubilities of components. A type of prediction model was applied to observe the long-term leaching behavior of major glass elements and surrogates. Diffusion coefficients and dissolution rate constants, the main parameters in the long-term prediction model, were obtained for glass elements and surrogate nuclides using experimental data for short and long-term periods. The model could be used to predict long-term behavior of such elements to observe and assess the stability of vitrified waste forms.

Leaching behavior and characteristics of glass components and surrogate nuclides in radioactive vitrified waste forms.

Several vitrified waste forms were fabricated and characterized, which contain simulated radioactive waste incineration ash, and a long-term leaching test was conducted by an ISO method for 820 days to assess the chemical durability of vitrified waste forms. Two semi-empirical mechanism models were applied to find out the dominant leaching mechanism of glass elements. For glass elements, dissolution associated with diffusion was the dominant leaching mechanism and leaching characteristics also depend upon solubilities of components. A type of prediction model was applied to observe the long-term leaching behavior of major glass elements and surrogates. Diffusion coefficients and dissolution rate constants, the main parameters in the long-term prediction model, were obtained for glass elements and surrogate nuclides using experimental data for short and long-term periods. The model could be used to predict long-term behavior of such elements to observe and assess the stability of vitrified waste forms.

Retention of some radionuclides in furnace lining during incineration of radioactive wastes

The incineration is one of the widely used method for treatment of solid radioactive wastes. The high volume and weight reduction coefficient (100–150 respectively 10–15) are advantages of this method. The greater part of radionuclides from solid radioactive wastes is retained in ash. From point of view of workers external irradiation, the radionuclides accumulation in furnace lining is one of risk factors. The Kalinit ŽO 1200 is furnace lining material on NPPRIs Experimental Incineration facility. In the first step the sorption properties of this material from137Cs,60Co,54Mn,65Zn solutions were studied. The best results had60Co, its distribution coefficient was 7036 kg · dm−3. Cesium-137 was not absorbed on this material. The cylinders (height 5 cm, diameter 2 cm) from lining materials were made latest and were applicated inside the furnace and technological tract to study sorption properties from combustion gases. The penetration of radionuclide into lining material was studied too. The results obtained with this experiments are described in this paper.

Experience with radioactive waste incineration at chalk river nuclear laboratories

Chalk River Nuclear Laboratories is a nuclear research centre operated by Atomic Energy of Canada Limited. A full-scale waste treatment centre has been constructed to process low- and intermediate-level radioactive wastes generated on-site. A batch-loaded, two-stage, starved-air incinerator for solid combustible waste is one of the processes installed in this facility. The incinerator has been operating since 1982. It has consistently reduced combustible wastes to an inert ash product, with an average volume reduction factor of about 150:1. The incinerator ash is stored in 200 L drums awaiting solidification in bitumen. The incinerator and a 50-ton hydraulic baler have provided treatment for a combined volume of about 1300 m 3/a of solid low-level radioactive waste. This article presents a review of the performance of the incinerator during its six years of operation. In addition to presenting operational experience, an assessment of the starved-air incineration technique will also be discussed.