William E. Daniel

Millimeter-Wave Monitoring of Nuclear Waste Glass Melts – An Overview

Molten glass characteristics of temperature, resistivity, and viscosity can be monitored reliably in the high temperature and chemically corrosive environment of nuclear waste glass melters using millimeter-wave sensor technology. Millimeter-waves are ideally suited for such measurements because they are long enough to penetrate optically unclear atmospheres, but short enough for spatially resolved measurements. Also efficient waveguide and optic components can be fabricated from refractory materials such as ceramics. Extensive testing has been carried out at a frequency of 137 GHz to temperatures up to 1500 C. Performance of refractory waveguides at high temperature has been shown to be satisfactory. A novel new method for viscosity monitoring has also been tested with simulated nuclear waste glasses. It has been shown that a viscosity range of over 30 to 3000 Poise can be monitored with one instrument. Results of these laboratory tests and the potential of millimeter-wave sensors for on-line glass process monitoring are presented.

Millimeter wave diagnostics of materials and melts

Diagnostics of materials in high-temperature, optically inaccessible environments can be reliably achieved with millimeter-wave methods and components. A 137 GHz heterodyne receiver using a thermal return reflection (TRR) technique and ceramic waveguides tested to 1500/spl deg/C have been used to demonstrate the capability to measure temperature, emissivity, viscosity, and salt layer formation in laboratory and pilot scale melter tests.

Radioactive Waste Evaporation: Current Methodologies Employed for the Development, Design, and Operation of Waste Evaporators at the Savannah River Site and Hanford Waste Treatment Plant

Evaporation of High level and Low Activity (HLW and LAW) radioactive wastes for the purposes of radionuclide separation and volume reduction has been conducted at the Savannah River and Hanford Sites for more than forty years. Additionally, the Savannah River Site (SRS) has used evaporators in preparing HLW for immobilization into a borosilicate glass matrix. This paper will discuss the methodologies, results, and achievements of the SRTC evaporator development program that was conducted in support of the SRS and Hanford WTP evaporator processes. The cross pollination and application of waste treatment technologies and methods between the Savannah River and Hanford Sites will be highlighted. The cross pollination of technologies and methods is expected to benefit the Department of Energys Mission Acceleration efforts by reducing the overall cost and time for the development of the baseline waste treatment processes.

Millimeter-Wave Measurements of High Level and Low Level Activity Glass Melts

The objective of this project is to develop on-line sensors for characterizing molten glass in high-level and low-activity waste glass melters using millimeter-wave technology. Existing and planned waste glass melters lack sophisticated diagnostics due to the hot, corrosive, and radioactive melter environments. Without process control diagnostics the Defense Waste Processing Facility (DWPF) at Savannah River, the Waste Treatment Plant (WTP) at Hanford, and planned melter upgrades operate by a feed forward process control scheme that relies on predictive models with large uncertainties. This scheme limits production throughput and waste loading. Also without on-line diagnostics melter operations are blind to anomalies such as foaming, combustion gas build up, noble metals accumulation, liquidus crystals, and salt layer formation, which can disrupt operations leading to costly down times. Using the unique capabilities of millimeter-waves on-line monitoring for important melt process parameters such as temperature profiles, emissivity, density, viscosity, and other characteristics will be developed. Once successfully developed and implemented significant cost savings would be realized in melter operations by faster production through put, reduced storage volumes (through higher waste loading), and reduced risks (prevention of anomalies).