Nuclear Materials Detection by Photoneutrons
Developing the Experimental Model of the Device for Nuclear Material Detection by Photoneuton Technology, Optimization of Device Detection Parameters to Meet the Solution of Non-Proliferation Problems
Tech Area / Field
- FIR-NSS/Nuclear Safety and Safeguarding/Fission Reactors
- INS-DET/Detection Devices/Instrumentation
8 Project completed
Senior Project Manager
Genisaretskaya S V
Kurchatov Research Center, Russia, Moscow
- University of British Columbia / TRIUMF, Canada, BC, Vancouver
Project summaryThe experts in nuclear weapons believe that hand-made nuclear bombs with the power equivalent to several kilotons of trinitrotoluene could be fabricated by large terrorist organization if fissile materials will be available to them. Recently, there were revealed the attempts of application of “dirty” bomb being a mixture of conventional explosive and radioactive material. The explosion of such bomb will result in radioactive contamination of the vast area. The threat of possible nuclear and radioactive terror thus causes the necessity of stringent control of trafficking of nuclear materials.
The nuclear materials include fissionable, radioactive materials, heavy water and other materials which can be used for nuclear fuel production or nuclear weapons manufacturing. At the illegal trafficking through the control gate of nuclear object or crossing the custom border, these materials can be concealed in the hand luggage, large-size containers, transport means. The sensitivity (minimal mass of detectable material) of efficient control system should meet requirements for the State System of account and control of nuclear materials.
The detecting abilities of currently used «passive» detection systems (radiation monitors) had practically reached their limits, especially in case of masked or shielded radioactive and fissile materials. These systems cannot detect non-radioactive materials such as lithium or heavy water since these materials do not emit the ionizing radiation.
In general, the neutron technologies are capable to reveal the concealed fissile materials. However, the detectable mass of fissile material concealed in the large-size container is too big (more than 1 kg). Neutron technologies are unable to detect some other nuclear materials (e.g., heavy water or some radioactive materials). Moreover, a sufficient activation of controlled object after its irradiation by fast or thermal neutrons is possible.
A preliminary study carried out in the RRC “Kurchatov Institute” shows that the trafficking of nuclear materials can be effectively controlled by the photo-neutron technology. This technology is based on the following. The threshold of photo-neutron reaction for the fissile, radioactive and other sensitive materials is relatively low (<8 MeV), whereas the mentioned threshold for the common construction materials is much higher (>10 MeV). This technology can be implemented in the following way. The pulsed electron beam with the energy W = 8-10 MeV is scanned in vertical direction and incident on the metal target. At each moment, the electron beam produces a very narrow-angle bremsstrahlung with the same maximum energy (W) as the electron beam energy. However, due to the vertical scanning of electron beam, the averaged directional diagram of bremsstrahlung has the “knife”-type shape extended in the vertical direction. This “knife”-type bremsstrahlung irradiates the controlled object. The object moves along the device in horizontal direction so all zones of the object are irradiated during the process of control. In case of presence of concealed sensitive materials, the photoneutrons are emitted and can be effectively recorded. As far as at each moment the electron beam produces a very narrow-angle bremsstrahlung, and photoneutrons are emitted instantly (compared to the rate of electron beam scanning), this technology provides the possibility to define the location of concealed sensitive material. The part of bremsstrahlung passed through the object is recorded by the gamma-detector array. This “X-ray” image of the controlled object can be used for advancing the revealing capabilities of the method.
According to the preliminary estimates, the sensitivity of this method meets the requirements of RF State System of account and control of nuclear materials [Main Regulations of Account and Control of Nuclear Materials. NP-03-01, 2001] including alpha- and beta- isotopes and non-emitting materials (e.g., lithium, deuterium).
Some constructional materials contain natural isotopes with a low threshold of photo-neutron reaction (e.g., Fe-57 in steel). However, its content is very low (e.g., steel contains only 2% of Fe-57). The preliminary analysis shows that the induced activity in the object (the passenger car was taken as an example) after application of photoneutron technology will be much lower than the maximum permissible level, so this technology can be used for repeated control of objects.
The aims of the project are as follows:
– Experimental demonstration of nuclear material detection by photoneuton technology as applied to the physical protection of nuclear objects;
– Theoretical and experimental optimization of beam target construction and electron beam parameters for achievement of the best probabilistic parameters of nuclear material detection;
– Determination of the parameters related to the efficiency of nuclear material detection by photoneutron technology;
– Getting the required information and working-out the proposals for development of the pilot device available for physical protection of the nuclear object.
The following results are expected through the project implementation:
1. The experimental model of the device including the electron linear accelerator, target for narrow-angle bremsstrahlung production, diagnostic equipment.
2. The project of the beam scanner for shaping the “knife”-type bremsstrahlung.
3. Experimental photoneutron yields at the irradiation of various constructional materials and nuclear materials.
4. Optimized parameters of electron beam for achievement of the best probabilistic parameters of nuclear materials detection.
5. Parameters related to efficiency of nuclear material detection (detection probability, false alarm probability, time of detection, sensitivity).
6. Proposals for development of the pilot device based on the commercial electron accelerator for physical protection of the nuclear object.
The nuclear materials for experimentation will be taken from the Storage for nuclear materials locate in the RRC “Kurchatov Institute”.
The works will be carried out by the specialists of RRC “Kurchatov Institute”. The specialists have wide experience in experimentation at the electron accelerator, assembling and tuning the equipment for recording of ionizing radiation, data processing and optimization, solution of applied nuclear problems. The team includes 8 Doctors of Philosophy (PhD).
Our assessment shows the photoneutron technology provides the better sensitivity, range of detectable materials, accuracy of localization, responsiveness compared to the existing methods of passive and neutron control technologies. It provides the better ecological compatibility compared to the neutron technologies.
The current project meets the ISTC goals and objectives since most of the participants previously worked on the nuclear weapon related problems. The participation in the project will promote their re-orientation to the peaceful activity. Moreover, the current project is targeted to the improvement of nuclear safety and safeguarding.
The results of the project can be used in systems for physical protection of nuclear objects and custom control systems.
The authors are sure that the results of the project will be also used in the similar works of foreign collaborators. The following forms of cooperation are planned: joint use of the experimental facilities, hardware optimization, search for the commercial applications, independent verification of the results, information support of the work.
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