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Cast Uranium Cermet for Shielding Casks

#2693


Production and Testing of Cast Cermet on the Base of Stainless Steel and Depleted Uranium Dioxide as Applied to its Use as Shielding Materials in Constructions of Casks for Spent Nuclear Fuel and Radioactive Wastes

Tech Area / Field

  • ENV-RWT/Radioactive Waste Treatment/Environment
  • MAT-ALL/High Performance Metals and Alloys/Materials
  • MAT-COM/Composites/Materials

Status
8 Project completed

Registration date
05.02.2003

Completion date
21.03.2008

Senior Project Manager
Tocheny L V

Leading Institute
VNIIEF, Russia, N. Novgorod reg., Sarov

Supporting institutes

  • VNIIKhT (Chemical Technology), Russia, Moscow\nAll-Russian Scientific Research Institute of Non-Organic Materials named after A. Bochvar, Russia, Moscow

Collaborators

  • Oak Ridge National Laboratory, USA, TN, Oak Ridge

Project summary

It is the objective of the Project to produce and test the properties of cast metal-ceramic alloy (cermet) on the base of stainless steel and depleted uranium dioxide (DUO2) as applied to its use as shielding material in construction of casks designed for transportation, storage and disposal of spent nuclear fuel (SNF) and radioactive waste (RW).

Currently in the USA, Russia and other countries large stocks of depleted uranium (more then 106 tons) are accumulated and still is being accumulated, which have not yet wide practical application because these are mainly wastes (dumps) of separating production as extremely toxic uranium hexafluoride (UF6) and uranium tetrafluoride (UF4). There is still more amount of contaminated (recycled) stainless steel, coming from nuclear industry facilities for utilization.

One of the ideas of solution of important ecology and economy problems on utilization of materials noted is production of uranium cermets of their base for its use in construction of shielding casks for SNF and RW.

Uranium cermets have potentially a number of advantages over other shielding materials (stainless steel, lead, metal-concrete, metallic uranium and others) currently used in casks for SNF and RW and, besides, mass production of cermet casks can serve as economical way of utilization (disposal) of depleted uranium excess and recycled stainless steel in the interests of ecology.

The main problem on the way of design of cermet casks for SNF and RW is development of economical technologies to produce uranium cermets with high radioactive shielding and operational characteristics and producing from the material large-size items (containment shells, baskets). To solve the problem it is necessary to carry out large experimental-and-technology and research works: from production and testing of cermet samples in laboratory conditions up to development of industrial technologies of uranium cermet obtaining and production of large-size elements of shielding casks.

It is supposed within the framework of the Project to carry out laboratory experimental researches on the problem noted.

This work is suggested by Oak-Ridge National laboratory (USA), which deals with the problem of long-term (in geologic time) storage of SNF in underground depositories.

The Project is of practical interest for all countries having nuclear power and dealing with the problem of handling with SNF and RW.

Investigations being planned to carry out within the framework of the Project and their results belong to the category of applied researches.

As a result of the Project completion:


· laboratory technologies of uranium cermet melting and cast will be developed;
· shielding, operating and technology characteristics of cast uranium cermets will be experimentally investigated;
· demonstrational pilot-scale samples made of cast uranium cermets will be manufactured;
· practical recommendations on the most acceptable from the economic point of view industrial technology of cast uranium cermet obtaining and production large-size elements of shielding casks will be developed.

After the Project completion, in the case of adopting a positive resolution on possibility of use of obtained uranium cermet for designated purpose, arises a long-term prospect of further investigation connected with practical drill and assimilation of industrial technologies of production of large-size elements shielding casks as well as with development of such casks construction.

Results of the investigations carried out within the framework of the Project will be applied:


- in the field of materials science (new cermet materials and technologies of their obtaining);
- in the field of ecology and environment protection (safe SNF and RW handling).

The project suggested meets purposes and aims of ISTC, in particular, will enable scientists and specialists involved into development and manufacturing of nuclear weapon to carry out science and research activity in peaceful purposes, will allow one to support applied research and development of new technologies in the field of ecology and environment protection. Te results of the Project will help to address international technical problems connected with utilization (disposal) of ecologically hazardous radioactive materials.

The Project has a commercial potential and its implementation will make for development of the market system in Russia. The Project contributes to engage specialists of nuclear-weapon complex into international science community in the interests of the world science and engineering development.

The following activities will be carried out under the Project:

1. Development of laboratory experimental-technological base:


- Development of technical requirements for cast uranium cermet;
- Develop laboratory melting furnace as well as additional equipment to control melting and casting processes;
- Fabricate moulds, shaped casting molds, as well as laboratory experimental facility for centrifugal casting;
- Prepare the laboratory rolling machinery;
- Choose initial components to produce cermet (stainless steel, UO2 powder, binding and addition elements);
- Prepare equipment for express testing of cermet characteristics.

2. Develop laboratory technologies to produce cermet and fabricate cermet pilot-scale prototypes and models of cask shells for testing:


- Perform experimental melting and express testing in order to choose optimum composition (recipe) of cermet and technological production regimes;
- Testing of cermet casting technologies (shaped casting, centrifugal casting, etc.) and develop optimum technological processes;
- Testing of cermet rolling techniques (sheets, shells) and develop optimum technological processes.

3. Produce pilot-scale prototypes and models of cask shells for testing in Russia and US based on the developed laboratory technologies.

4. Delivery of pilot-scale cermet models for US full-scale testing:

5. Prepare laboratory-testing base and carry out comprehensive testing of cermet operation and technological characteristics:


- Metal-graphical studies of micro/macrostructure;
- Studies of physical-mechanical characteristics;
- Studies of thermal-physical characteristics;
- Studies of nuclear-physical features;
- Studies of chemical and corrosion resistance taking into account radiation impact;
- Studies of technological characteristics (processing using mechanical methods, weldability, potential application of shielding coatings, etc.);
- Select and justify optimum composition of uranium cermet considering its properties and technological effectiveness.

6. Summary and analysis of the performed studies results. Development of practical recommendations on cermet production industrial technologies and cermet cask shells production.

Programs and methods of experimental investigations will be discussed with foreign collaborators.

It is planned in the course of the Project performance for data exchange:


- to provide foreign collaborators with comments on technical reports, submitted by participants of ISTC projects;
- to organize joint working seminars where collaborators could take part in discussion of the results obtained in course of the Project performance.

Besides, collaborators could take part in technical inspection of the Project activity, carried out by the ISTC specialists.

During the Project performance science and engineering potential will be used as well as vast experience of high-qualified specialists of RFNC-VNIIEF, VNIIKhT and A.A. Bochvar VNIINM, working in the field of uranium and its compound material science, development of technologies of uranium materials obtaining including these for shielding casks, as well as in the field of investigation of nuclear-physical, chemical, mechanical and other properties of uranium and materials on its base.

Works on the Project will be carried out using science and research experimental bases being in possession of organization-participants, free of additional general fitting-out, using certified equipment and setups, instrumentation and experimental methods meeting modern science and engineering requirement and approaches to solution of problems set by the Project.

It is planned to use a number of original methods and patented inventions while conducting the investigations.


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