Shielded Air Atmosphere Glove Boxes for Fabrication of MOX Fuel and Rods for Research and Power-Grade Fast Neutron Reactors
Shielded air atmosphere glove boxes for fabrication of oxide fuel have been widely used in nuclear industry featuring the equipment with quite clear technical requirements. So, the glove boxes for fabrication of oxide uranium fuel must ensure, as a minimum, a leak-proof shielding containment to provide a separate atmosphere, deployment of process and auxiliary equipment, and process operations.
As for glove boxes for fabrication of oxide uranium-plutonium fuel (MOX), engineering requirements are much more stringent. Plutonium reactivity imposes significant constraints on the composition and temperature of the air atmosphere. Air-tight shielded glove boxes are fabricated for a definite purpose and differ in thicker walls, special glass, a pressure relief valve connected to an active ventilation system, and a contamination solution drain valve.
Sosny R&D Company develops, fabricates and delivers shielded glove boxes according to GOST 28164-89 "Radiation-Shielding Glove Boxes. Types" and GOST R 52153-2003 "Radiation-Protective Boxes. General Specifications".
The glove boxes are made of radiation-resistant stainless steel.
They are class 3H to NP-016-2005.
Seismic resistance to NP-031-01 is category II.
The glove boxes are equipped with air-tight doors and customized with mechanical equipment (rollers, conveyors, etc.). Electric actuators are installed outside the containment. If necessary, the table in the glove box may incorporate thermal vacuum furnaces for drying the product, as well as other equipment. The glove boxes have LED lamps.
Negative pressure makes up 200 Pa (regulated by draft and head gauges ТНМП-100-М1 or ТНМП-52-М2). The glove boxes may be equipped with temperature and moisture transducers.
Inlet, exhaust and maintenance vents with electrically-driven flaps make part of the glove boxes.
The glove boxes have control cabinets (installed on the frames) and protected electric and pneumatic systems.
The radiation shielding can be enhanced by attaching shielding plates with shielded windows to the front wall of the glove boxes.
If necessary, the glove boxes can be interconnected through air-tight corridors and airlocks to ensure continuous process.
In 2011, such shielded glove boxes were developed for SSC under contract with SverdNIIkhimmash OJSC. Now they make part of the complex for production of MOX fuel for the BN-800 reactor facility.
In total, the following five air atmosphere glove boxes were developed:
- for a dioxide uranium dispensing system incorporating a dispensing hopper, a vibrating feeder and a balance,
- for reloading the product from an operation container into a transfer cask. The glove box has a hoist to transfer a TUK-30 cask and its lid, as well as an operation container transfer mechanism,
- for receiving and transferring containers with plutonium dioxide to the storage and dispensing cells,
- for inspection of lid sealings and decontamination of a plutonium dioxide container,
- for outgoing non-destructive evaluation of fuel pellets.
The glove boxes are designed to incorporate access doors, air-lock hatches, viewing windows, glove and process ports, a suction-and-exhaust ventilation, and lamps.
The glove boxes are all corrosion-resistant stainless steel construction with walls 2.5 mm thick and the table 10 mm thick. Other elements are made of paintworked carbon steels. The length of the glove boxes may vary from 2000 to 2500 mm. The glove boxes are leak-proof and are subject to positive pressure testing. They are equipped with operation suction-and-exhaust and maintenance ventilation systems, as well as a decontamination solution draining system. The radiation shields have the following thickness:
- 3-10 mm for the uranium dioxide dispensing glove box;
- 50 mm for the reloading and receipt glove boxes;
- 20 mm for the inspection and decontamination glove box.
The glove boxes are 3НЛ class to NP-016-2005.
All the glove boxes passed acceptance tests.
Skilled personnel, process and control services, corresponding capabilities, as well as a Rostechnadzor license are available for designing and fabrication of the glove boxes.
In 2013, Sosny R&D Company developed and delivered shielded glove boxes and in-box equipment for a pilot facility for vibropacking and sealing of fuel rods for the BOR-60 reactor and the MBIR reactor being built at SSC RIAR.
The pilot vibropacking and sealing facility designed for testing pieces of equipment for fuel rod fabrication made part of the complex for fabrication of oxide mixed uranium-plutonium fuel, vibropacked fuel rods and fuel assemblies.
The line of the glove boxes includes:
- an input control glove box incorporating equipment for weighing and batching nuclear fission products into drying containers,
- a glove box for thermal vacuum drying of granulate incorporating two furnaces, a vacuum pump and a vertical conveyor for loading/unloading baskets with the containers,
- a glove box for fuel portioning incorporating a dispenser and a balance,
- a glove box for loading the fuel into fuel rods incorporating equipment for mixing, vacuuming, helium purging, consecutive loading of the fuel portion, vibropacking and loading pellets of the upper end blanket.
In addition, the glove box has a torch and equipment for primary decontamination and fuel components distribution control throughout the fuel column.
Negative pressure of 200 Pa is maintained inside the glove boxes. Dry air supply maintains the temperature of 20 °С and relative humidity of 15% or less. The glove boxes are equipped with a two-stage air filtering system.
To ensure proper fabrication of fuel rods, the area has the following ancillary systems:
- cladding vacuuming,
- helium purging into the cladding,
- argon purging for welding the plug to the cladding,
- compressed air purge,
- suction-and-exhaust ventilation,
- feed water and decontamination solution supply,
The control system of the glove boxes provides for independent control of each furnace and maintains the temperature conditions due to smooth power adjustment. The control system has digital process variables recorders, built-in energy-independent memory for storing data archive accumulated for a long time, and capabilities for on-line graphic representation of measured variables (temperature, pressure) and data transfer.
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