Floating NPP with Low Enrichment Fuel
Low Enrichment Uranium Core for Floating Nuclear Power Plant Reactor (FNPP) as a way of Resolving Weapon’s Nuclear Material Nonproliferation Problem
Tech Area / Field
- FIR-ENG/Reactor Engineering and NPP/Fission Reactors
- FIR-FUE/Reactor Fuels and Fuel Engineering/Fission Reactors
3 Approved without Funding
All-Russian Scientific Research Institute of Non-Organic Materials named after A. Bochvar, Russia, Moscow
- Experimental Designing Bureau of Machine Building (OKBM), Russia, N. Novgorod reg., N. Novgorod
- Korea Atomic Energy Research Institute, Korea, Yusung Taejon\nArgonne National Laboratory (ANL), USA, IL, Argonne
Project summaryCurrently in Russia under development is a design of a floating nuclear power unit to be used as a power source and also for water desalination in various regions world-wide. The power unit comprises 2 reactors of the KLT-40 type 150 MW each. This reactor type is well mastered and primarily used in atomic ice-breakers. It is designed in such a way that its high reliability and safety are ensured both under normal operating conditions and in power transients. However, its core fuel contains highly enriched uranium (20% and more).
However, the use of the highly enriched U in the fuel of the ice-breakers for floating nuclear power plants on the KLT-40 base gives rise to a problem relating to the proliferation of nuclear materials usable for military or terroristic purposes, particularly, if FNPPs are operated in countries not having nuclear weapons.
The problem may be resolved via the application of uranium enriched by not more than 20% which conforms to the IAEA requirements as well as via the specific management of fuel assemblies out of pile.
The use of low enrichment uranium is feasible at the expense of the application of higher U content dispersion fuel, for example, at the expense of increasing the volume fraction of UO2. To further increase the power resources and cost-effectiveness of the core consideration will also be given to an option using a high U content metallic fuel, U-Mo, U-Mo-Si, U-Nb-Zr (the uranium content of the fuel composition being more than 8 g/cm3).
The principal requirements placed on KLT-40 dispersion fuel elements comprise high irradiation resistance, leak-tightness of cladding integrity and serviceability in power transients. The fuel rod design shall ensure the stability of fuel rod geometry throughout the whole life-time. At the first stage the fuel elements have to provide the maximal fuel burn-up of 0.4 g-f.p./cm3 which corresponds to some 52,000 MW/t U as calculated for the standard VVER-1000 fuel rod.
The technical solutions inherent in the design of the fuel elements allow a subsequent several times increase of the burn-up with minimal improvements of fuel elements and this will result in a much higher cost-effectiveness of the core.
High irradiation resistance, serviceability in power transients and high uranium content (more than 8 g/сm3) make fuel elements competitive with standard fuel element of PWR and BWR reactors.
The compensation of the excess reactivity is promoted by the application of burnable absorber pins (BAP) that have also to remain integer throughout the whole life-time. Gadolinium compounds resistant to aqueous corrosion are used as a BAP material.
The claddings of fuel elements and BAP will be fabricated from zirconium alloys E-110 and E-635.
The application of < 20% enriched U requires the following:
– calculate the physical and thermophysical characteristics of the core;
– analyze the operating conditions of fuel rods and BAP;
– formulate the requirements for design, quantity of fissile material, stability and service parameters of fuel rods and BAP;
– ensure the criticality safety of floating plant reactor using low enrichment fuel;
– establish the specific requirements for the systems of the reactor unit and plant;
– study the specificity of the spent fuel management;
– develop the design of the higher uranium content fuel element as applied to the KLT-40 reactor;
– develop the technology of the fuel element fabrication;
– validate the fuel element design as applied to the specified burn-up and operating conditions;
– develop the design of burnable absorber pins as applied to the KLT-40 reactor;
– develop the technology of the burnable absorber pins;
– validate the burnable absorber design as applied to the specified operating conditions.
Aside from this, special measures have to be considered to eliminate the unsanctioned access to fuel assemblies when managed out-of-pile.
The power resource of this core has to ensure the cost-effective operation of the plant and be maximal as far as it is possible in terms of the serviceability and safety to provide for the minimal reactor reloads and risk of the unsanctioned access to fuel assemblies upon their handling.
The objective of the Project is to design and validate floating nuclear power plant cores having the highest cost-effectiveness, < 20% enrichment fuel and maximally feasible cycle without intermediate reloads which is to ensure the minimal risk of the unsanctioned access to the nuclear fuel of the FNPP, particularly when operated in countries that do not have nuclear weapons.
The Project work will result in:
1. An explanatory note on the core design with the needed drawings and the validation of the fuel assemblies and core.
2. The calculations of the core physics and thermohydraulics throughout the cycle.
3. The validation of the nuclear safety.
4. The determination of the nuclide composition of the discharged fuel.
5. The validation of the requirements for the systems of the plant and fuel handling that are inherent in the low enrichment fuel.
6. An explanatory note on the concept of ENPP fuel cycle including its economic characteristics and development of special measures against the unsanctioned access to fuel assemblies out-of-pile.
7. An explanatory note on the fuel design and procedures of the fuel element fabrication with the needed drawings, calculations and validation.
8. An explanatory note on the fuel design and procedures of burnable absorber fabrication with the needed drawings, calculations and validation.
To implement the work suggested in the Project many highly qualified specialists are assumed to be attracted who were previously engaged in designing and testing cores and fuel elements of nuclear power facilities for the mass-destruction weapon (m. d. v.) delivery as well as fuel elements of commercial nuclear reactors for defense purposes. Their participation in the Project guaranties, on the one hand, the high scientific level of the implemented work, and, on the other, will retain and pert the highly qualified scientific staff of designers, technologists, material scientists to the resolution of civil problems.
Co-operation with foreign collaborators will take place during execution of the Project.
The foreign collaborators are assumed to participate in the discussions of the programs, working plans, final results and other issues relating to the nonproliferation of nuclear materials as well as in the more exact formulation of the requirements for the fuel element and core features as well as the fresh and spent fuel management.
The joint efforts of this kind will make it possible to establish more exactly the framework and priorities of the suggested investigations as well as to coordinate the contents of the deliverables.
The main requirement placed on the core is its reliability and safety. The core design will be based on the technical solutions used in the design, physical profiling and reactivity compensation methods employed for the cores of ice-breakers now in operation. For the validation of the characteristics of the core and its elements use will be made of the design codes that were verified and certified for the ice-breaker reactors of the KLT-40 type.
The higher uranium content fuel elements and burnable absorbers will be designed on the basis of novel materials and novel technological solutions that will make it possible with minimal future improvements in the fuel elements to extend the burn-up by several times, thus, increasing the core cost-effectiveness.
In the work implementation use will be made of practically tested methods and approaches used in designing fuel rods and cores of atomic ice-breakers.