The project partners will benefit from the development of an advanced cold source with optimization of cold neutron output and safety characteristics supported by mathematical modelling for their own purposes in the following way : PNPI (Gatchina) operates a similar research reactor with cold sources and faces to installation of cold moderators at the new high flux reactor PIK being constructed as well as TUM (Garching) is starting a CNS project for its new high flux reactor with the involvement of L'Air Liquide, consequently experience gained in this "COLDNESS" project will be profitable at the Gatchina and Garching reactors.
The aim of this joint research project named by the acronym COLDNESS (COPERNICUS co-Operation for coLD NEutron Source Study) is to establish a close partnership of four institutions for the advanced study and development of cold neutron source (CNS) technology as well as the construction and installation of a Hydrogen moderator at the Budapest Research Reactor, one of the scarce high rank large scale facilities in Central Europe.
Background The cold neutron source is the most important investment for scientific research at the upgraded and regularly operating since November, 1993 Budapest Research Reactor. The International Scientific Advisory Council of the Budapest Neutron Centre (BNC) gives first priority to the installation of CNS to enhance substantially the research capacity. A detailed feasibility study has been performed providing the general framework of the construction programme, and the technical design was started in January 1996. The CNS construction is supported by Hungarian national funds and the International Atomic Energy Agency.
Technical Description The main functional element of the cold source is a special doublewalled cell filled with 450 cm3 of liquid hydrogen, placed at the end of a horizontal tangential beam tube in a hole in the Be reflector around the core and positioned close to the maximum of thermal neutron flux distribution in order to extract intense beam of slowed down neutrons.
The proposed design concept with direct cooling of the condensed hydrogen in the moderator cell by cold helium gas (produced in a He-refrigerator) provides novel technical solution with enhanced performance in cold neutron out-put as well as improved safety characteristics due to the extra inert gas barrier around the hydrogen containing moderator cell preventing from the hydrogen-air mixture formation, the minimization of the necessary hydrogen amount and making far less complex the out-of-pile hydrogen system.
The results of the energy release calculation in the feasibility study show that the estimated total heat load is about 100 W and this relatively low heat release makes possible the implementation of the direct cooling system. This concept was also approved by the National Regulatory Body.
Benefits and deliverables The installation of an advanced CNS at the Budapest Research Reactor contributes to the implementation of new high resolution methods of neutron beam research and measurements (e.g. for investigation of condensed matter properties, texture and residual stress analysis of industrial materials, prompt gamma activation analysis of microelements for monitoring of environmental pollution etc.), thus yields considerable enhancement of the regional research potential. The requested support is a 45% contribution to the CNS project at BNC and allows essentially the purchase (at one of the EU manufacturers) and installation of the He-refrigerator, a major component of the cold source.
Unfortunately other problems represent principal difficulties. The role of the new cardinal experimental solution would be of major importance for the further development of dynamic tensiometry. The analysis of all known methods of the dynamic surface tension measurements had lead to the conclusion that among all existing methods the oscillating bubble method is less affected by the difficulties of interpretation mentioned above. Meanwhile this method until now is implemented for low frequencies only.
Funding SchemeCSC - Cost-sharing contracts
188350 St. Petersburg