Safety of nuclear installations is dealt with utmost importance in Member States and in the nuclear industry. Engineering solutions and their impact on the safety of liquid metal cooled fast reactors (LMFRs), as well as their development and deployment, were discussed during a three day technical meeting, which closed at the IAEA yesterday.
"Modern reactor technologies incorporate inherent and passive safety features," said Dohee Hahn, Director of the IAEA Division of Nuclear Power. "It is very important to gather feedback from the different organizations involved in developing these innovative devices and to share experience on development, design and operation of these systems."
Specific systems to improve reactor safety performance during the unlikely event of an accident have been developed in nearly all fast reactor programmes, and a large number of proposed systems have reached various stages of maturity.
Experts from ten Member States with active development programmes or interest in fast reactor technology presented and discussed specific shutdown systems to improve reactor safety performance during accidents. They also identified priories for further R&D, based on technology gap analyses.
"The assessment of passive safety systems often requires advanced simulation and modelling which is complex due to sensitivity to multiple phenomena," explained Stefano Monti, Section Head of the IAEA Nuclear Power Technology Development Section and Scientific Secretary of the meeting.
Along with the design philosophy, various special shutdown systems specifically engineered for prevention of severe accidents were presented. New criteria pertinent to shutdown systems in the currently evolving safety design criteria for innovative fast reactors were also discussed. The meeting also highlighted the importance to increase margins to failure and avoid coolant boiling during very severe unprotected plant conditions when the conventional shutdown systems are not functioning as designed.
The meeting participants recommended that available international knowledge and experience in the area be documented in a well-structured format.
"One of the outcomes of this meeting is the initiation of a new study on passive shutdown systems for fast neutron systems" said Stefano Monti. The study results will be published in a technical report in the IAEA Nuclear Energy Series that will include information collected about existing operational systems and innovative concepts that are being developed in various countries.
"This new publication will be a useful source for Member States interested in gaining technical expertise in developing passive shutdown systems for fast neutron systems, and it will highlight the importance of research and developments in this area." said Mr Monti.
Inherent and passive safety features are especially important when active systems for reactor shutdown are not functioning properly. In reactor designs with inherent safety features, the plant remains in a safe condition solely on the basis of the laws of nature. These laws ensure that all performance characteristics remain within safe bounds under all conceivable circumstances. Passive safety is a broader concept and implies that no human intervention, no triggering signals and no supply of external energy are required for the reactor to remain in a safe condition.