Nondestructive Burnup Measurements
Nondestructive Control of a Burnup Depth of Spent Fuel for RBMK-1000 Reactors in Storage Pond of Nuclear Power Plants
Tech Area / Field
- FIR-NSS/Nuclear Safety and Safeguarding/Fission Reactors
- FIR-INS/Nuclear Instrumentation/Fission Reactors
8 Project completed
Senior Project Manager
Khlopin Radium Institute, Russia, St Petersburg
- FEI (IPPE), Russia, Kaluga reg., Obninsk\nLeningrad NPP, Russia, Leningrad reg., Sosnovy Bor
- Los-Alamos National Laboratory, USA, NM, Los-Alamos\nEuropean Commission / Joint Research Center / Institute for Systems, Informatics and Safety, Italy, Ispra
Project summaryThe problem of the nondestructive control of fissioning materials in spent fuel of atomic power stations is a one of the main point in a number of problems of control on the illegal moving of nuclear materials as well as the security of nuclear safety.
The nondestructive control of burnup depth and the amount of fissioning materials in spent fuel assemblies of RBMK-1000 reactors has a special importance at present time. The evaluation of fissioning inventory in spent fuel assemblies of RBMK-1000 can be obtained at the moment only by results of calculations and has estimated character.
The amount of spent fuel assemblies is estimated in tens of thousands and constantly grows. Till now there is no final decision about their further destiny of this vast amount of spent fuel (its reprocessing, disposition, storage under the continuous control and so on). Meanwhile it is clear that at any accepted strategy of the spent fuel management it is necessary to have the detailed information on the contents of fissioning isotopes and their distribution in such extended objects as assembly RBMK-1000 reactor (length of an active zone of one assembly is around 7 m).
The large amount of spent fuel assemblies and conditions of their storage (storage pond) restricts sufficiently the diapason of the possible control methods. The traditional high resolution-methods do not available without changing of pool design due to large dimension of the object and limited measurement time of one assembly. It is necessary also to take into account that the performance of measurement should be safe from the point of view of radiation and nuclear safety and does not interrupt other technological operations in the storage pond.
One of the most suitable control methods of burnup depth is the method of passive -scan of spent fuel assembly directly in the storage pond. Here the detecting part of the measuring device moves on a case with spent fuel assembly located in a measuring volume. The spent fuel assembly there is motionless providing the radiation safety of measurements.
The determinant for the use of a method of a passive neutron scan is an opportunity to carry out the proper calibration of device by means of connection between the intensity of own neutron radiation with burnup depth and contents of fissioning isotopes. There are two possibilities in this case:
· The performance of a large volume of destructive measurements for spent fuel assembly fragments (dilution) with various enrichment, operational campaign, location in an the reactor core and so on.
· The performance of measurements for a set of spent fuel assembly with use of – scan and certificated techniques for the definition of burnup depth and fissioning isotopes in fuel.
The first way is represented as an improbable one in view of its vast cost and time and effort consuming. To carry out such kind of work directly on NPP is quite impossible. On the contrary, the method of the - scan graduation can be fulfilled directly in a place of spent fuel assembly storage.
In V.G.Khlopin Radium Institute together with the scientists of the A.I.Leipunski Institute of Physics and Energetics and Leningrad Nuclear Power Station the work on the development of the techniques for the nondestructive analysis of burnup depth and contents fissioning isotopes in a power reactor fuel are carried out. One of priority directions of researches is the development of a technique for the nondestructive control of burnup depth in spent fuel assembly of RBMK-1000 reactors. A number of experimental installations is constructed and first measurements of assemblies in the storage conditions of Leningrad NPP were performed. Experimental data on burnup depth distributions on spent fuel assembly length are received. Simulation of spent fuel assembly characteristics was fulfilled in Radium Institute on the stand "SCAT" imitating the storage pond. The results were compared with calculated ones and to results of the destructive analysis of spent fuel assembly fragments performed by the Radium Institute experts.
The main goal of the work is a realization of measurements for several sets of fuel assemblies with the various characteristics (burnup, cooling time, initial enrichment and so on) and the development on their basis of a technique for the control of burnup depth of RBMK-1000 assemblies with an error is not worse 10-15 %.
Such kind of results are necessary for the maintenance of the account and control of nuclear materials and also the maintenance of nuclear safety and fall into a number of the most important problems (with high priority in the field of international cooperation).
Potential role of foreign collaborators:
The problem of the burnup depth control and plutonium accumulation in the spent fuel of power reactors is an international problem as a component of the programs of the account, storage and control for moving of nuclear materials and maintenance of nuclear safety where ever more of the experts worldwide participate in the decision. Association of efforts in this direction will allow to develop the most acceptable approach and to create the methodology of the decision of this urgent problem.
We are sincerely interested in the participation of the foreign experts who have great experience in the performance of similar research. We hope that their assistance will be rendered at least in the form of consultations of specific steps of the project, which will contribute to successful performance of the proposed project.