Uranium Container for Fuel Transportation
Development of a Technical Design for DU-shielded Transport Cask with Increased Spent Nuclear Fuel Specific Loading
Tech Area / Field
- FIR-NSS/Nuclear Safety and Safeguarding/Fission Reactors
8 Project completed
Senior Project Manager
Tocheny L V
VNIIEF, Russia, N. Novgorod reg., Sarov
- All-Russian Research and Designing Institute of Complex Energetic Technology, Russia, St Petersburg\nAll-Russian Scientific Research Institute of Non-Organic Materials named after A. Bochvar, Russia, Moscow\nState University of Nizhny Novgorod / Research Intitute of Mechanics, Russia, N. Novgorod reg., N. Novgorod
- Sandia National Laboratories, USA, NM, Albuquerque
Project summaryEcological hazard posed by NPP spent nuclear fuel (SNTP) places to the containers designed for its transportation and long-term storage exacting demands on radiation and nuclear safety, strength and thermal operation modes, in compliance with IAEA standards, Current serial transport casks intended for WER reactors SNF transportation comprise all-metal steel assemblies. Radiation safety and strength is provided by container thickness and neutron shield and thermal modes - by virtue of water solution available in its cavity. Such designs are peculiar for high metal consumption and low spent fuel specific loading. Therefore, in the mean time the task to study possibility of development of a state -of-the -art competitive transport cask for highly burned-out NPP fuel is rather pressing which is also stipulated by the present situation related to WER spent fuel utilization. Majority of potential SNF suppliers do not have or exhausted their resources to store accumulated SNF; this fact forces them to seek new options for solution of this problem. The easiest and most efficient way is to place SNF inside the containers with further storage at special sites or in buildings of simplified construction. In addition, improvement in transportation safety necessary because of moral and physical wear of currently used serial containers that -were designed 20 years ago is also very acute. Introduced updating and modifications could not eliminate its principal drawback, i.e. safety dependence on attending personnel activities and restrictions on transportation: Moreover, service life of these containers expires in 1998-2005. In this respect replacement of serial containers with modern ones which operational safety and reliability would be dependent on their design is considered to be timely and actual.
Objective of the Project "Development of a Technical design for DU-Shielded Transport Cask with Increased Spent Nuclear Fuel Specific Loading " is to conduct fundamental and experimental investigations involving foregoing RF Minatcm scientific institutions aimed at the development of a transport cask for spent nuclear fuel storage with performance not inferior to its foreign analogs. In the course of the project implementation it is proposed to use material with high density and atomic number - U238, as efficient, g-radiation shield and boronated polypropylene as solid neutron shield. It is for the first time in Russian practice that depleted uranium (DU) will be used as g-radiation biological shield and boronated polypropylene as solid neutron shield. These activities will result in the development of a transport cask (TC) design for transportation and long-term storage of VVER-440 spent nuclear fuel which shall enable to:
1. Enhance TC consumers' quality by virtue of increase in cask fuel capacity maintaining overall and weight properties;
2. Obtain new computational and experimental data con container and materials properties (radiation protection efficiency, nuclear safety, etc.):
3. Save deficient high - alloy stainless steel required for manufacturing of the container. Steel consumption for manufacturing of the uranium- shielded container decreases by the factor of 2 as against all-metal one;
4. Apply (utilize) waste from fissile and storing uranium productions that is not widely adopted but stored causing ecological hazard- 30 t. of DU will be required for manufacturing of one container;
5. Adjust SNF container design to IAEA standards;
6. Improve working conditions for TC amending personnel.
Principal Sections / Stages of the project:
1. Section of computational and fundamental investigations. Provide possibility to develop uranium-shielded container for NPP spent nuclear fuel transportation and long-term storage;
2. Section of the experimental investigations. Prove results of computational and fundamental investigations regarding the above possibility;
3. Section of design and technological investigations. Validate possibility of the development of the uranium-shielded container from л the point of view of its manufacturing.
Technical Approach and Methodology
Work under the project is carried out using equipment available in the Participating Institutions, i.e. fast pulsed reactor ~BIGR. mass-spectrometers, gas analyzers, tensile-testing machine "INSTRON ", electronic instrumentation, high-vacuum inductive and electron-beam furnaces, electric resistance furnaces. b and g -spectrometers, metalographic and electron microscopes, facilities for compatibility. and containment investigations and is mainly based on the then developed technological approaches for manufacturing, methodical approaches for computational fundamental and experimental investigations on mechanical and thermal material properties, isotopic composition of materials, materials decomposition kinetics under elevated temperatures and initial radiation as well as for benchmark tests of the cask for power and thermal effects.
The following available mathematical software and constant support is applied during computational and fundamental investigations, namely: Computing Center; neutron constants libraries; codes for solving neutrons transfer equations by Monte Carlo Method; codes for numerical solution of thermal conductivity non-stationary equation; codes for calculation of cask designs with regard for contact interaction under dynamic and static loadings and service programs for data array processing.
Methodical approach used in KRFNC-VNTIEF for nuclear charge development is applied in the process of the container development. It comprises the following:
- general design layouts are 'worked out in compliance with specifications indicated in statement of work;
- computational and fundamental estimates of the conformity of the designs operational limits to specifications are performed. Basic design alternative is selected relying on computational estimates with further design documentation working out;
- series of the computational i and fundamental investigations for a full-scale cask and for its mock-ups is performed (radiation and nuclear safety, strength, vibration, thermal modes, compatibility of separate materials with structural materials etc. is validated);
- computational and experimental investigations of the materials not applied previously as w ell as of those information about which is incomplete are carried out;
- tests at model installations and full scale mock-ups for the loadings indicated in specifications are performed. Accuracy of the design solutions and mathematical models conformity to the physical с object behavior is verified based on tests results. If necessary tolerances envisaged in mathematical models are adjusted and new computational and fundamental investigations are carried out;
- adjustment of the design to specifications outlined in the statement of work is performed relying on the results of the computational and fundamental investigations and testing results obtained at mock-ups and model installations.
Research and development carried out under this project will allow to develop a technical design of a relatively cheap DU-shielded transport cask with increased spent nuclear fuel capacity which is not inferior in performance to its foreign analogs.
Results of the efforts under the project will be of a scientific and practical value. Firstly, it is for the first time in domestic practice that depleted uranium is used as y-radiation biological shield and boronated polypropylene as solid neutron shield. Secondly, development of a transport cask will allow to adjust shielding technique for the Russian NPP spent nuclear fuel storage to IAEA standards; to enhance its consumers qualities by virtue of increase in cask fuel capacity maintaining overall and weight properties; to save high-alloy stainless steel required for manufacturing and to apply (utilize) waste from fissile and storing uranium productions that is not wide) adopted in national economy and stored causing ecological hazard. In addition, results of fundamental and experimental investigations obtained under this project could be used in other foreign and domestic projects to develop SNF containers for other types of NPP reactors.
Contribution of Foreign Collaborators
HErnpIoyees of Sandia National Laboratories (SNL) are proposed to be involved as foreign collaborators to review this project. They could participate in the development of a DU-shielded transport cask for NPP spent nuclear fuel as Sandia National Laboratories carry out activities on investigation of a possibility to develop uranium-shielded container for spent nuclear fuel with the support of the US Department of Energy.