Shielded inert atmosphere gloveboxes for nitride fuel fabrication

Shielded inert atmosphere gloveboxes were developed for process chains intended to test the equipment and to try out the processes of fabrication/re-fabrication module (FRM) of mixed uranium-plutonium nitride (MUPN) fuel as a part of the pilot demonstration energy complex (PDEC) being created at the Siberian Group of Chemical Enterprises (SGChE).

In 2015, Sosny R&D Company won the tender for manufacture of a complex of experimental facilities (CEF) to develop and test the basic procedures of MUPN fuel fabrication at the SGChE. It was the first attempt to create a chain of gloveboxes with inert (nitrogen) atmosphere containing experimental equipment for MUPN fuel fabrication. The in-box equipment comprises crushing, grinding, mixing and powder granulating devices, a furnace, presses, powder composition and pellet size control means. The units with the most appropriate and effective design are planned to become the commercial prototypes of the PDEC FRM equipment. The CEF also includes auxiliary equipment that supports the functioning of the gloveboxes and in-box equipment.

Detailed design documents for the CEF gloveboxes were developed at SverdNIIkhimmash. Under this project, the experts of the Sosny R&D Company developed the documents for auxiliary equipment and systems that support the operation of the experimental units, as well as for press tools of increased wear resistance for pellet pressing, fabricated the equipment prototypes and performed acceptance tests at the customer's site. The overall quantity of the gloveboxes delivered to the SGChE is 18.

 

CEF

 

The development of the equipment for the process support area (PSA) was the second step in PDEC FRM creation. The PSA is a part of the PDEC FRM analytical laboratory. It provides technical and process support to the core FRM production with the aim to test engineering solutions, improve process modes, provide recommendations concerning quick change of the process parameters of fuel production. The PSA backbone is a chain of gloveboxes with biological shielding to protect the personnel from external exposure. The gloveboxes are designed in accordance with GOST R 52153-2003 "Shielded gloveboxes. General Technical Requirements". The chain is divided with leak-tight partitions installed on the transfer airlocks between the gloveboxes. The products travel from glovebox to glovebox on a horizontal conveyor.

Controlled inert atmosphere is maintained inside the gloveboxes by feeding nitrogen from the centralized system into the inner glovebox volume. The glovebox walls are made of 12Х18Н10Т corrosion-resistant steel. The gloveboxes are equipped with changeable fire-resistant pre-filters.

This project implied all steps of the PSA creation, including the development of the terms of reference and design documents. The project was completed by field supervision over the equipment mounting at the customer's site and the following acceptance tests.

The PSA glovebox chains include:

  • Powder preparation gloveboxes (crushing, mixing, weighing),
  • Gloveboxes for powder parameters monitoring,
  • Glovebox with a press for making pellets,
  • Glovebox with a furnace for carbothermal synthesis,
  • Gloveboxes for granulation and powder preparation,
  • Glovebox with a pellet sintering furnace,
  • Gloveboxes for pellet parameters monitoring,
  • Scrap handling gloveboxes,
  • Analyzers glovebox,
  • Pellet storage glovebox,
  • Gas purification glovebox with a corresponding unit.

The PSA gloveboxes in which the furnace for carbothermal synthesis of nitrides and the furnace for pellet sintering are located are equipped with a local gas purification system and an off-gas purification system.

The temperature of the off-gases discharged into the ventilation does not exceed 60 °C and the mass concentration of aerosol particles is not more than 0.5 mg/m³.

 

PSA

 

The main characteristics of the inert atmosphere gloveboxes for MUPN pellets fabrication:

Safety Class to NP-016−05                                                              2N

Seismic Resistance Category to NP-031-01                                      I

Climatic Category to GOST 15150-69                                               У4.2

Maximum amount of plutonium dioxide                                             300 g

Maximum amount of uranium dioxide                                               not limited

Minimum leaktightness                                                                      6.7x104 m3Pa/s

Minimum vacuum gauge pressure in the boxes                                200 Pa

Oxygen and moisture concentration                                                  below 50 ppm

Service life                                                                                         30 years

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