Characteristics of FBNR

The following table shows a summary of the requirements of a small reactor without on-site refuelling and their applicability to FBNR.

Requirement Demonstration of applicability
Small in size FBNR is small in nature. The optimum size for the FBNR is 40 MWe. The larger size up to a maximum of 60 MWe can be achieved only at the cost of a lower thermodynamic efficiency.
Modular The reactor is modular in design; therefore, any size reactor can be built from the basic module. The modular aspect of the reactor leads to the mass production processes resulting in better economy and higher quality products.
No need for on-site refueling Each module is fuelled in the factory. The fuelled modules in sealed form are then transported to and from the site. The FBNR has a long fuel cycle time and, therefore, there is no need for on­site refuelling.
Proven Technology FBNR makes an extensive use of a proven technology namely that of PWR. Its fuel is of HTGR type.
Diversity of applications The FBNR is a land­based nuclear power plant for urban or remote localities The FBNR is designed to produce electricity alone or to operate as a cogeneration plant producing electricity and potable water or steam for industrial purposes. As an option, the FBNR may be designed for district heating.
Refuelling in the factory No refueling on the site is needed because the fuel elements are collected in the fuel chamber and transported to the factory for refueling under surveyed condition. Refuelling is done by the replacement of fuel chamber.
Long fuel cycle time The length of the fuel cycle chosen depends on the economic analysis of the fuel inventory for particular situation of the reactor and its application. The HTGR fuel elements have high burn up capacity. The replacement of fuel chamber is done at any desired time interval and could be set at every 10 years or for the reactor lifetime.
No fuel reshuffling No reshuffling of fuel is necessary because the fuel elements go from fuel chamber to the core and vice versa without the need of opening the reactor.
No fresh fuel storage on site There is no need for fresh fuel to be stored at the reactor site since the sealed fuel chamber is transported to and from the factory where refueling process is performed.
Short period of spent fuel storage on site The spent fuel that are confined in the fuel chamber and kept cool by its water tank. It can be sent back to the factory at any time when the radiological requirements are met.
Inaccessibility of fuel to unauthorized individuals No unauthorized access to the fresh or spent fuel is possible because the fuel elements are either in the core or in the fuel chamber under sealed condition so no clandestine diversion of nuclear fuel material is possible.
High fabrication quality & economy The FBNR is shop fabricated thus it guarantees the high quality fabrication and economic production process.
Easy transportation The reactor is about 2 m in diameter and 6 m high, while its fuel chamber is only 2 m in diameter and 1 m high, thus the transportation to the site and return is very easy and convenient.
Easy dismantling The reactor loop being made of relatively small components, at the end of its useful lifetime, the reactor can be dismantled and even disposed of in one piece with simplicity.
Reduced number of operators required The reactor can be operated with a reduced number of operators or even be remotely operated without any operator on site. This is possible due to the inherent safety characteristics of the reactor as the reactor operates when all the operating parameters are within the designed ranges. In any other situation, the electricity does not reach the pump to operate the reactor and the fuel elements will fall out of the core by the force of gravity or remain in the fuel chamber under a highly sub critical and passively cooled conditions.
Simplicity & economy The simplicity of design and the lack of the need for large number of redundancies in control system, make the reactor highly economic.
Simple infrastructure The infrastructure needed for the plant using FBNR is a minimum. The important processes are performed in the shop that can be in a regional centre serving many reactors.
Underground containment and environment The inherent safety and passive cooling characteristics of the reactor eliminate the need for containment. However, an underground containment is envisaged for the reactor to mitigate any imagined adverse event, but mainly to help with the visual effects by hiding the industrial equipments underground and presenting the nuclear plant as a beautiful garden compatible with the environment acceptable to the public.
Utilization of spent fuel, nuclear waste and environment The spent fuel from FBNR is in a form and size (1.5 cm diameter spheres) that can directly be used as a source of radiation for irradiation purposes in agriculture and industry. Therefore, the spent fuel from FBNR may not be considered as waste, in a peaceful world of the future, as it can perform a useful function. They may also be reprocessed after their use as radiation source. Should reprocessing not be allowed, the spent fuel elements can easily be vitrified in the fuel chamber and the whole chamber be deposited directly in a waste repository. These factors result in reduced adverse environmental impact.
High conversion ratio The moderator to fuel volume ratio of FBNR is about 0.7-0.8, compared to 1.8-2.0 for a conventional PWR. Thus, the neutron spectrum in the FBNR is harder resulting in a higher conversion ratio than the 0.55 for PWR that may be about 0.7-0.8. It may permit using MOX fuel, even in the beginning of the fuel cycle without needing enriched uranium, resulting in a higher conversion ratio.
Fool proof nuclear non-proliferation characteristic The non-proliferation characteristics of the FBNR is based on both the extrinsic concept of sealing and the intrinsic concept of isotope denaturing. Its small spherical fuel elements are confined in a fuel chamber that can be sealed by the authorities for inspection at any time. Only the fuel chamber is needed to be transported from the fuel factory to the site and back. There is no possibility of neutron irradiation to any external fertile material. Isotopic denaturing of the fuel cycle either in the U-233/Th or Pu-239/U cycle increases the proliferation resistance substantially. The u se of thorium based TRISO type fuel will also contribute to this end. Therefore, both concepts of "sealing" and "isotope denaturing" contribute to the fool proof non-proliferation characteristics of FBNR.
High level of safety Strong reliance on inherent and passive safety features and passive systems.
Enhanced safeguard ability Fuel elements are confined in the fuel chamber that could be sealed by authorities for inspection at the end of the fuel life. The reactor vessel is cladded by neutron-absorbing materials to eliminate the possibility of neutron irradiation of any external fertile material.
Technology transfer The technology could be open to all nations of the world under the supervision and control of international authorities.
Enhanced safety Reactivity excursion accident cannot be provoked. The reactor core is filled with fuel only when all operational conditions are met.
Mitigation of steam generator leakage problem The water heated in the reactor core passes through an integrated steam generator producing steam to drive the turbine.
Reduced adverse environmental impacts Underground containment in a garden like site.
Long core lifetime Insertion of fresh fuel into the core is performed continuously to compensate for fuel burn-up.
Resistance to unforeseen accident scenarios Any probable accident, through cutting off the power to the pump, causes the fuel elements fall out of the core driven by the force of gravity. The normal state of control system is "switch off". The pump is "on" only when all operating conditions are simultaneously met.
Low fuel temperature A heat transfer analysis of the fuel elements has shown that, due to a high convective heat transfer coefficient and a large heat transfer surface­ area, the maximum fuel temperature and power extracted from the reactor core is restricted by the mass flow of the coolant corresponding to a selected pumping power ratio, rather than by design limits of the materials.
Dual purpose plant The FBNR can operate within a cogeneration plant producing both electricity and desalinated water. A Multi­Effect Distillation (MED) plant may be used for water desalination. An estimated 1000 m 3 /day of potable water could be produced at 1 MW(e) reduction of the electric power. It may also produce hot water for district heating.
Low capital investment The simplicity of design, short construction period, and an option of incremental capacity increase through modular approach result in a much smaller capital investment.



 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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