The Innovative Plasma Tilting Furnace for Industrial Treatment of Radioactive Waste - 14420

The operation and maintenance of nuclear power plants, the nuclear fuel cycle in general, research laboratories and pharmaceutical, medical and industrial facilities generate large amounts of low-level radioactive wastes which, along with the historical radioactive wastes from past nuclear activities, need to be treated to minimise the volume to be disposed of. Plasma technology offers a very effective way of treating this waste with a high volume reduction factor (VRF), free from organics, liquids and moisture, and meets without doubt the acceptance criteria for safe storage and disposal. By means of a plasma beam of approximately 5000°C, the inorganic materials are melted into a glassy slag containing the radioactive isotopes while the organic material is gasified and afterwards oxidized in an afterburner and purified in an off-gas cleaning system. This paper describes the principles of plasma, the different waste feed systems, off gas treatment, operational experience and future plasma plants. In particular a new fullscale plasma facility for the treatment of radioactive waste at the Kozloduy Nuclear Power Plant in Bulgaria is described. This facility is designed and now under construction by the Joint Venture Iberdrola Ingeniería y Construcción and Belgoprocess. INTRODUCTION: PLASMA PROCESS Plasma is considered by many to be the fourth state of matter, following the more familiar states of solid, liquid and gas. Plasma consists of a collection of free moving electrons and ions and energy is needed to strip electrons from atoms to make plasma. With insufficient sustaining power, plasma recombines into neutral gas. Heat energy, where added to liquid, converts the liquid into gas. The addition of heat energy to a gas converts the gas into plasma. Lightning is an example of the plasma state of matter. Lightning is not a flame; it is rather a very high temperature beam of energy. The plasma knowledge was not exploited until the period at NASA’s space program during the sixties. Considerable development in plasma technology was achieved in an effort to produce an intense heat source for carrying out reliability tests on re-entry heat shields of space crafts and missiles. After more than five decades, plasma technology is being utilized worldwide in many industrial processes, e.g. metal cutting, metallurgical application,