Development of Plasma Torches for Waste Management and R&D on Fusion reactor's materials Pakistan Tokamak Plasma Research Institute (PTPRI) Pakistan Atomic Energy Commission June 07, 2022 Email: [email protected] • Pakistan started its nuclear fission power program in 1971 with CANDU type power reactor • Currently fission power plants are contributing a total sum of 3500 MW of electricity in national grid • Several Cancer Hospital and Agricultural center are also serving the nation • In parallel there are two research reactor for the training of young engineers and scientists • Established in 2007 named “NTFP – National Tokamak Fusion Program” • Renamed as “PTPRI – Pakistan Tokamak Plasma Research Institute” in 2020 • Vision: Tokamak as fusion energy source and a mean of innovative technological development for Pakistan • Small training facility has been established • Research publications and M. Phil / M. S students projects • Part of three (03) IAEA-CRP (Coordinated Research Projects) • Expansion to Medium sized Tokamak in progress • Technological infrastructure in key areas of fusion power • Multi-dimensional links with the international community • Joining of ITER and world’s mega projects of DEMO • Support of IAEA and CERN to interact ITER as non-Member Tokamak Devices at PTPRI: - GLAST – 1 - GLAST – 2 - GLAST – 3 - First plasma: 6:30 pm 28th June, 2012 - MT – 1 - MT – 2 Indigenous Development at PTPRI: - Vacuum vessels - Magnetic Field Coil Systems (0.33 – 1.0 Tesla) - DC Power Supplies (10kV – 20kV) - Power switches (~MW, ~mS) - IGBT gate drive controller - Trigger controller - Microwave (2.45Ghz, 3kW) - Rogowski Coils - 3 – D Magnetic Probes - Langmuir Probes - Optical diagnostics - Data acquisition (20 – 100 Channels) Technological Application Projects at PTPRI: - Low Temperature Plasma (DC and RF for coating, cleaning) - Plasma torch (250W, 500C) (For waste management) - HTS coil (DC magnetic field ~ Tesla) - Lithium Evaporator - High power RF mono-pulse Generation (2.45GHz) - Eddy current probe (Metallic Cracks) - High Frequency / H Voltage (Biomedical / agricultural) - Prototype NBI system (~1 kW) • Development of plasma torches for waste management • R&D on fusion Reactor’s materials • Radioactive waste management is one of the major challenges faced by the nuclear industry • One of the solution is the vitrification of waste (transformation into compact glassy slag) through high power plasma torches • Plasma torches (temp. up to 10,000 Celcius) can reduce volume of low and intermediate level radioactive waste • by 50 times as compared to the untreated waste • over 10-times that of pre-compacted waste • by a factor of at least 2 for previously super-compacted wastes • Decreased storage requirement for nuclear repositories, minimum risk of contamination and eliminates the need of pre-disposal processes like segregation, pre-treatment, incineration compaction etc. • Large saving in financial expenditures with min. risk Specifications: Power: 250 Watts Flame Temperature: ~500 °C Design Features: • Compact design having tangential entry of gas flow • Copper anode with nozzle shape and half cone angle of 30° • Tungsten cathode of 3.2 mm dia. at center of anode • Swirling effect for maximum exit velocity and laminar flow • Strong flow circulation at a swirl number of 1.73 • Vortex flow constraints the plasma at center of anode for maximum stability • Rectified DC breakdown voltage of 4kV • Breakdown and plasma flame formation at the cathode tip Parameters and Specifications: - Type of plasma: DC – APP - Power: 0.25 kW - Current: 62 mA - Voltage: 4 kV - Atmosphere/pressure: Atmospheric - Gap between electrodes: 5 mm - Gas flow rate: 25 L min⁻¹ Dimensions (mm): - Tungsten cathode: 3 - Copper anode: - Inner diameter: 3.2 - Outer diameter: 50 - Nozzle cone angle: 60 - Height: 25 - Torch body: - Inner diameter: 30 - Outer diameter: 50 - Gas inlet diameter: 6 - Height: 80 - Perspex cathode holder: - Rod diameter: 22 - Cap diameter: 50 - Height: 80 - Helical annular space: - Groove depth: 2 - Groove width: 4 - Groove pitch: 8 Components and Specification: - Step-up transformer: - Power: 250 VA - Input voltage: 230 V@50 Hz - Output voltage: 4000 V - Diode: - Model: HVM12 - Peak reverse voltage: 12,000 V - RMS voltage: 8400 V - DC blocking voltage: 12,000 V - Rectified current holder: 350 mA - Capacitors: - Model: H1423M - Rated voltage: 450 V - Capacitance: 470 μF - Resistor: - Resistance: 1 kΩ Design Schematics showing: - Cathode - Anode - Screw - Outer Body - Gas Inlet - Cathode Holder - Isometric View and Cross-sectional View - Breakdown region in the conical anode at swirl termination CFD parameters: - D = Coil Dia = 26mm - d = Wire Dia = 6mm - Coil straight length = L = 57mm - Number of turns = 7 - Comparison of No-swirl flow torch vs Swirl flow torch Experimental Layout schematic including Power Source (transformer, bridge rectifier, capacitor), Cathode, Anode, Plasma Torch assembly, Flow Controller, Pressure Gauge, and Nitrogen Cylinder (Gas Supply System). Photograph and demonstration setup of the operational Plasma Torch at PTPRI, showing pressure regulator, high voltage probe, and torch flame. • A 3kW plasma torch is in fabrication phase • Technological infrastructure for high power torches • Enhancement of power from 3kW to 100kW in three steps • Establishment of Plasma Medical Waste Treatment Facility (3-4 Torches, ~ 20-30kW per torch) • Development of Plasma based Radioactive Waste Treatment Facility (3-4 Torches ~ 50-100kW per torch) • Applications of plasma torches in other technological areas (bio-medical, agricultural, industrial etc.) • Technological challenges of fusion energy are intimately linked with the availability of suitable materials capable of reliably withstanding the extremely severe operational conditions of fusion reactors. • Materials for DEMO and commercial reactor materials are being designed and investigated to meet the requirements • We have also started R&D activities in this important area • We have ion sources “Tandem accelerator (10 MV, 25 MeV) and Ion Implanter (120 MeV)” and research reactors • Besides, we have SEM (Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), XRD (X-ray Diffraction), AFM (Atomic Force Microscopy), XPS (X-ray photoelectron) • Some basic studies have been done on Tungsten, Molybdenum and Inconel alloys • Excellent initiative by IAEA on the subject • Multi-dimensional efforts is the need of time to synergize Fission – Fusion • IAEA should force the member states to work on fast track on this extremely important aspect • Joint working teams of Fission-Fusion scientists / engineers should be formed by IAEA in member states