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Advanced Pulsed Neutron Sources

#2962


Theoretical and Experimental Investigation of the Dynamics of Advanced Pulsed Neutron Sources of Periodic Operation

Tech Area / Field

  • FIR-NSS/Nuclear Safety and Safeguarding/Fission Reactors
  • FIR-EXP/Experiments/Fission Reactors
  • FIR-NOT/Nuclear and Other Technical Data/Fission Reactors
  • FIR-OTH/Other/Fission Reactors

Status
3 Approved without Funding

Registration date
19.12.2003

Leading Institute
Joint Institute of Nuclear Research, Russia, Moscow reg., Dubna

Supporting institutes

  • VNIIEF, Russia, N. Novgorod reg., Sarov

Collaborators

  • Kyoto University / Research Reactor Institute, Japan, Osaka

Project summary

This project aims at carrying out theoretical and experimental research in the dynamics of advanced pulsed neutron sources of periodic operation (PNS), including high power PNS. The research is directed towards rising the safety and reliability of PNS operation. The task is currently a focus because interest in employing PNS in different fields of science and technology has increased recently. Along with unique presently operating setups based on pulsed nuclear reactors (IBR-2), powerful proton accelerators with nonmultiplying targets (IPNS, LANCE, etc.) and subcritical systems with electron accelerators (of the IBR-30 type), there exist a number of projects for the development and construction of PNS oriented to obtaining of intense pulsed neutron fluxes for scientific purposes and for the “transmutation” (burn-up) of long-lived fission products in Japan, Europe, Korea, China, and Russia (JAERY, JAPAN).

The problem of ensuring safe and reliable operation of PNS in service today and of those under design is closely related with the dynamic properties of the system and naturally, its solution depends on the type of PNS. However, there are a number of problems common to all PNS whose solution will provide an understanding of many complicate processes going in the PNS core, which in turn, ensures a higher level of safety and reliability of such setups. The issues of the dynamics of periodic operation PNS was partially discussed in ISTC projects 0682 and 1932 in relation with the estimation of the nuclear safety of such systems. However, as the experience of the operation of the pulsed reactor IBR-2, partly reflected in the above-mentioned projects, shows the dynamics of any pulsed system with a sufficiently large power may change essentially if the burnup is 2% or higher. As a rule, this results in a decrease of the stability of the pulsed system. This is why a theoretical investigation of the issues of PNS dynamics must be followed by its experimental verification. At present, at the reactor IBR-2 and booster IBR-30 in Dubna there is accumulated rich experience in the field of the dynamics of pulsed systems of periodic operation and there exist possibilities for carrying out of the verifying experiments. In our opinion, studies of the dynamic properties of advanced PNS must involve the investigation of all possible feedback channels, including not only fast (from fractions of second to tens of seconds) and superfast (acting as the power pulse develops) but also much more slower channels (hours, months, years). Such integrated approach to the investigation of PNS dynamics makes it possible to solve in the main the problem of full control of the chain reaction (i.e., of Keff) in any regular or emergency situation.

The proposed project involves the investigation of a number of the critical problems of dynamics, which is necessary to assess and increase the safety of PNS in service and under project.

The principal goals of the project are:

- Theoretical and experimental investigations of random effects of reactivity in PNS for reactor (critical) and booster (subcritical) systems with a proton or electron accelerator. The designing and construction of a system for the measurement of the PNS noise characteristics. The investigation of the IBR-2 power pulse energy noises and analysis of the IBR-30 booster noises. The theoretical, methodological and experimental investigations are proposed to be carried out using the IBR-2 reactor.

- Improvement of the models of the dynamics of the booster and reactor pulsed systems of periodic operation. The creation of software packages to simulate transitional processes of power and temperature in the active zone of PNS, including high power PNS. It is proposed to use the IBR-2 reactor for the experimental verification of modal calculations.

- Improvement and verification of computer codes for simulating of the time-dependent characteristics of PNS with the Monte Carlo method (e.g., the MCNP-code) using the different libraries of neutron constants. Carrying out of additional experiments to measure the pulse form in subcritical assemblies and at IBR-2 to enrich the experimental data base for the purpose of comparison with the results of time-dependent calculations.

- Comparison of the libraries of estimated neutron data based on the calculations of fast critical assemblies. To meet the goal, about 100 critical assemblies on fast neutrons with the different compositions of active materials and reflectors will be calculated using the different libraries of estimated neutron data. There will be also conducted additional calculations of changes in the isotopic composition of the PNS active zone for the different primary fuel compositions accounting for a real behavior of power variation with time. The calculated results will be compared with the experimental data and recommendations will be made.

- Development of a physical project of a periodic cascade booster as an advanced PNS. The analysis of the kinetics of such systems carried out under ISTC project 1932 was only aimed at evaluation of their general characteristics. It is proposed to conduct a more detail analysis for nearly real conditions of the systems. This will yield a realistic image of the cascade booster suitable for the development of an engineering project.

The principal advantage of this project is the possibility of fast realization due to long-term experience of IBR-2 and IBR-30 operation and that of creation of the intense resonance neutron source IREN (IREN is the Russian acronym of the Source of Resonance Neutrons) and of SAD (Subcritical Assembly Dubna) gained in the Frank Laboratory of Neutron Physics of JINR and due to the possibility of applying of the experience of other organizations’ development engineers and manufacturers of subcritical assemblies and active zones. Another advantage is the availability of equipment for measurements with the above mentioned facilities.

The proposed project provides the scientists and engineers previously involved in the development and manufacture of weapons with the possibility to apply their knowledge and experience for long-term non-military activities in the field of nuclear technologies.

The experience gained during the fulfillment of the project will be used in the operation, designing, and construction of intense PNS.

The work is expected to be completed within three years.


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