Non-Radiation Methods for Nuclear Materials Monitoring
Application of Non-Radiation Methods for Nuclear Materials Accounting, Control and Identification
Tech Area / Field
- INS-MEA/Measuring Instruments/Instrumentation
- FIR-NSS/Nuclear Safety and Safeguarding/Fission Reactors
- INF-SIG/Sensors and Signal Processing/Information and Communications
8 Project completed
Senior Project Manager
Bugaev D V
VNIIEF, Russia, N. Novgorod reg., Sarov
- Pacific Northwest National Laboratory / Battelle, Putting Technology to Work, USA, WA, Richland
Project summaryA set of measures limiting unauthorized use of nuclear materials (NM) of weapons quality - plutonium and highly enriched uranium (HEU) release as a result nuclear munitions reduction involves the provision of technical accounting and control of NM contained in protective containers, in storage and transportation. To achieve it a number of independent remote radiation and non-radiation methods can be used for diagnostics of the sealed container content. Development of the mentioned methods is actual to improve the system of monitoring the reduction of strategic weapons and the problem of nuclear weapon nonproliferation, that facilitates stability and International safeguards . In conditions of enhance activity of international terrorism the implementation of modern technical measures with regard to control will lead to the enhanced national system of storage safeguard system for NM weapons, nuclear fuel at the Minatom facilities, transportable nuclear power facilities and suppression of illegal NM handling.
At present special attention is given to the development of independent radiation (active and passive) and non-radiation methods for NM identification and control. They are based on the unique, inherent NM, nuclear physical, mechanical, thermal and etc. features. Registration of signals caused by some features of NM enclosed in the sealed container outside the limits of the container will make possible to identify actually the content, and control the enclosure of containers without unsealing the latter.
Selection of the method for radiation and non-radiation control is defined by specific conditions of the stated task, moreover, the radiation and non-radiation methods add each other.
Reliable systems of accounting, control and detection of NM are an important factor in stating the mode of nonproliferation and observation of treaties on nuclear weapons nonproliferation.
The C&A procedure are a system of organization, political and technical measures allowing to define reliably the integrity of NM under control. These procedures could be split conventionally into several phases beginning with the NM loading into a container to its disposal at the storage vault. It is evident that NM loading in the container and its durable storage takes place at different, and often distant (against each other) objects. Hence, the NM accounting and control procedures involve phases of transportation of containers with NM to storage vaults intended for permanent and temporal storage.
At present radiation methods are the main technical measures for NM accounting and control. It’s no doubt that theses methods are most efficient at the permanent storage vault. At the same time for other phases, especially for those related with transportation of containers with NM, cheaper non-radiation methods can be proposed for NM accounting and control. Application of the non-radiation methods for NM accounting and control at the stage of transportation or during disposal at temporal storage vaults, i.e. at the stages when the NM shape or its packaging don’t change, will lead to reduction of financial and material expenses regarding the NM control and accounting procedures.
The non-radiation methods of NM integrity can be based on the use of non-radiation features of both NM themselves, and a container, as a whole. The non-radiation methods can be applied both independently, and combined with other non-radiation and radiation methods, and, as a result, improve crucially the reliability and efficiency of the accounting and control procedures.
The methods under development can be also applied for control and accounting of non-nuclear materials.
It should be also noted that a possibility of NM non-radiation features (as well as other materials) is cumbered since a hypothetical violator will not aware of what specific non-radiation features of NM are under control. In the case when the hypothetical violator knows what non-radiation NM features are controlled, a combination of two methods will exclude, in our opinion, fully the possible simulation. So, for instance, a combination of procedures related with weighting and recording a vibroacoustic portrait excludes practically possible falsification since in this case one the NM element should be replaced by the one with the identical mass, density, geometrical sizes, the Young’s modulus and distribution of masses in the element.
Some of the non-radiation methods proposed allow to control the unchangeable state of the system “container+NM” in the continuous mode.
It is also foreseen in the Project to study the possibility of NM detection combining several non-radiation methods. The research is performed in this direction for the first time and is aimed to define non-radiation parameters of the NM and characteristics of the measuring equipment required for reliable identification and confirmation of NM integrity. These activities are essentially important from the viewpoint of setting the NM non-proliferation mode.
Scientists from RFNC_VNIIEF were one of the first who proposed the used of non-radiation NM control, accounting and identification methods that don’t demand special precautions while performing the work, as compared to the radiation ones, and apply common equipment for registration that leads to considerable cheapening of techniques.
The non-radiation NM control, accounting and identification methods are based on the identification principals for complex systems.
Non-radiation NM features can be split into the following categories within the frames of the tasks under consideration:
· Mechanical – Young’s modulus, Poison coefficient, shear modulus, etc.;
· Thermal – convective heat exchange, thermal conductivity coefficient, thermal expansion coefficient, etc.;
· Electromagnetic – dielectric permeability, conductivity, magnetic permeability, etc.;
· State of gaseous medium in a volume with NM.
Non-radiation NM control, accounting and identification methods proposed for consideration in our work can be pided into two groups:
a) Methods used earlier in other areas of engineering for identification of an object or determining its specific characteristics. Among these methods there are:
- Vibroacoustic methods. In this case as outer effects mechanical vibrations of various frequency are used, or pulse loads exciting the inherent vibrations in the object under research that possesses parameters inherent only to this object (inherent vibration frequencies, decrement of decay, etc.);
a) Induction-vibration methods. The operation of the unit is so that torsional currents of low frequency generated by the primary winding interact with the container and its components, and induce the relevant electromotive force with the value and phase-frequency characteristics between current parameters of the first and second coils depending on the container content;Method of thermal imaging. The method is based on the fact that NM releases heat into the environment. Registration of thermal fields around the object containing NM allows to control the available presence and quantity of NM in the object under research.b) Methods proposed by the RFNC-VNIIEF specialists for the first time, which were not used earlier for identification of complex system. Among them are the following:Method of torsional vibrations. In this case study characteristics of torsional vibrations of an object allows to control unchangeable moment of inertia relative to one or several arbitrary chosen axes;Method controlling the state of gaseous medium. The idea is to control the content and state (pressure, temperature, etc.) of gaseous medium in the container with NM;Magnetovibration methods. The method is based on excitation of the controlled object by low-frequency magnetic field and measurement of phase-frequency characteristics of its electrodynamics response.It is proposed to review various identification methods described in position a) within the frames of the Prject, demonstrate the research results with regard to capabilities of these methods for application in control, accounting and identification of NM.The second phase of the activities is development, creation of measuring facilities and study of capabilities of the methods described in position b) regarding control, accounting and identification of NM. It is assumed to demonstrate a magnetovibration method within the framework of the proposed project since this method has the following advantages against the other ones:simple and available registration equipment is used;
b) has the required sensitivity to the change of the object characteristics;
c) controls the object characteristics which couldn’t be simulated.
The activities on the Project involves the following:
- calculation-theoretical research of possible application of identification methods for complex systems in order to control the object integrity and define some mechanical characteristics of the object;
- perform experimental investigation to verify capabo=ilities of various techniques for NM C&A;
- perform the research in order to use a set of different non-radiation methods for improving reliability of NM control and identification
- define a spectrum of non-radiation NM parameters and requirements to the level of their precision for reliable NM identification;
- study possibilities of simultaneous application of several non-radiation methods to improve the reliable control and identification of NM;
- prepare and demonstrate the magnetovibration method.
The activities on the Project will be carried out by high-skilled specialists engaged earlier in the nuclear weapons program. The Project participants have a many-year experience in the fields related with acoustic and mechanical vibrations, thermal fields and electromagnetic radiation.
As a result of the Project fulfillment there is expected to:
• define a type of exciting and recorded signals allowing to reliably determine unchangeable state of the object under research;
• develop a technique for experimental research performance for the search of parameters that identify with stability the system under study;
• perform the demonstration experiment on magnetovibration method confirming the basic theoretical concept;
• demonstrate capabilities of the technique for a wide class of engineering systems;
• define a set of non-radiation NM parameters and required characteristics of measuring equipment needed for NM identification.
The proposed project:
1. Opens up opportunities for scientists and specialists from RFNC-VNIIEF to reorient their capabilities to the peaceful activities;
2. Encourages the integration of RFNC-VNIIEF scientists into the International Scientific Community;
3. Supports applied research and development of technologies for peaceful purposes, especially in the area of nuclear safeguards;
4. Facilitates resolving of technical problems in the area of NM control.
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