DeGeN measurement vehicle - our tool against nuclear terrorism

The Fraunhofer Institute for Technological Trend Analysis INT has a car-borne measurement system designated DeGeN (German acronym for "detection of gammas including neutrons") or literally translated, "rapier"), which makes it possible to detect and identify radioactive and, in particular, nuclear material, and was upgraded in 2012. Measurements can be performed while on the move or in stationary mode. The system can be integrated into vehicles the size of a station wagon or larger

Das Messfahrzeug DeGeN - unser System zur Prävention von Nuklearterrorismus

Das Fraunhofer-lnstitut für Naturwissenschaftlich-Technische Trendanalysen INT hat das Messfahrzeug DeGeN (DEtektion Gamma Einschließlich Neutronen) entwickelt und in 2012 modernisiert. Damit sind Nachweis und Identifikation radioaktiver und insbesondere nuklearer Stoffe möglich. Messungen erfolgen sowohl in der Vorbeifahrt als auch stationär. Das System ist in Fahrzeuge ab einer Größe eines typischen PKW-Kombis einbaubar

Simulation of a neutron multiplicity counter and comparison to validation experiments: Paper presented at International Workshop on Numerical Modelling of NDA Instrumentation and Methods for Nuclear Safeguards, 2018, Luxembourg, 16th-17th May 2018, co-hosted during the ESARDA 40th Annual Meeting

Neutron coincident counting is a useful tool, both to determine the nature of a neutron source and to extract parameters like the multiplicity, α-ratio and ultimately the mass. For the latter, well characterized detectors, like the Active Well Coincident Counter (AWCC), enable the measurement of uranium or plutonium content in the order of several grams. The multiplicity analysis also allows determining if an unknown neutron source emits fission neutrons and thus possibly contains special nuclear material. The Ortec Fission Meter is an instrument designed exactly for this purpose. It consists of a highly efficient moderated 3He neutron detector and a Windows Mobile handheld computer with dedicated software. It is powered by batteries and intended for field use. In order to get a deeper understanding of the measured data and to predict the dependence of the analysis on different parameters like additional shielding, Fraunhofer INT performed a Monte-Carlo simulation of the instrument. A MCNP simulation of the source assembly and the instrument results in the arrival times of the neutrons for one single source event. Further software modules allow to generate a pulse train and to perform the same analysis as the Fission Meter hard- and software does. While the count rate of the simulation and a validation experiment were in agreement, the calculated Feynman-Variance showed a significant deviation. The main cause is presumably a small fraction of double pulsing from the discriminator. The inclusion of this effect in the post-processing results in a very good agreement of measured and simulated data

D3S - results of qualification measurements of a wearable RIID for homeland security: Paper presented at INMM 2019, 60th Annual Meeting Institute of Nuclear Materials Management, July 14-18, 2019, Palm Desert, California, USA

A testing facility for qualification tests of measurement devices for radioactive and nuclear material was established at the Fraunhofer INT. This was done in the framework of the Illicit Trafficking Radiation Detection Assessment Program + 10 (ITRAP+10). The test methods were developed in the program based on ANSI and IEC standards. After the completion of the setup of the facilities, they are now used for the testing of various devices. This paper deals with tests in accordance with the ITRAP test procedures and the corresponding results obtained for the D3S detector from Kromek. The device is designed to be used as radiation isotope identifier (RIID) as well as personal radiation dosimeter (PRD). Therefore tests referring to both test methods were performed. The device contains a cesium iodine gamma as well as a non-helium-3 neutron detector and both kinds of sources were used for the device qualification. The tests are divided in tests of general requirements, radiological tests, and radionuclide identification tests. The tests of general requirements include for example tests of the user interface, battery requirements, documentation or audible and vibrational alarm. The radiological tests comprise tests concerning false identification rate, time to alarm, accuracy tests for photons, over range and gamma response of the neutron detector. The quality of the nuclide identification results is part of the radionuclide tests. Partly the requirements for PRDs and RIIDs are identical, partly not. For example the time to alarm value in which an alarm after the device is exposed to the source shall be created is 2 s for PRDs and 3 s for RIIDs. The D3S passed many tests, but also failed some. The tests also showed the limits of such test procedures. They are standard tests under fixed conditions whereas in reality different situations occur in which the obtained results may not turn out as well as the tests indicate. The paper gives results of the qualification tests done with the D3S as well as a suggestion for an additional close to reality test

Simulation of a neutron multiplicity counter and comparison to validation experiments: Presentation held at 83. Jahrestagung der DPG und DPG-Frühjahrstagung, Rostock, 10 - 15 March 2019

Neutron coincident counting is a useful tool, both to determine the nature of a neutron source and to extract parameters like the multiplicity, α-ratio and ultimately the mass of uranium or plutonium . For the latter, well-characterized detectors enable the determination in the order of several grams. The multiplicity analysis also allows determining if an unknown neutron source emits fission neutrons and thus possibly contains special nuclear material. The Ortec Fission Meter is an instrument designed for this purpose, equipped with a highly efficient moderated 3He neutron detector. In order to gain deeper understanding of the measured data and to predict the dependence of the analysis on different parameters like additional shielding, Fraunhofer INT performed a Monte-Carlo simulation of the instrument. A MCNP simulation of the source assembly and the instrument results in the arrival times of the neutrons for one single source event. Further software modules allow generating a pulse train and performing data analysis. While the count rate of the simulation and a validation experiment were in agreement, the calculated Feynman-Variance showed a significant deviation. The main cause is presumably a small fraction of double pulsing from the discriminator. The inclusion of this effect in the post-processing results in a substantial improved agreement of measured and simulated data

Highly efficient on-site detection of neutron sources with the INT measurement car DeGeN

Counter-acting the potential misuse of nuclear and radioactive material has been a subject of tremendous importance for quite a while, and the detection of such material is a key figure to counter-acting measures in that respect. Especially regarding nuclear material, detecting gamma and neutron radiation simultaneously on-site with high efficiency provides a good chance of retrieving such material during transport after it was removed from nuclear facilities, either as a malicious act or simply by chance. The Fraunhofer INT's (Institute for Technological Trend Analysis) measurement car DeGeN (detection of gammas including neutrons) is equipped with highly sensitive 3He neutron detectors and 12 l plastic detectors for gammas. After a reconfiguration of the measurement system, including new gamma detectors, the INT was given the opportunity of verifying the system's detection limits at the premises of WIS (Bundeswehr Research Institute for Protective Technologies and CBRN Protection) in Munster, Germany. Two different neutron sources were used for the experimental determination of the detection limits concerning neutrons. The results were then compared to theoretical detection limits which had been calculated previously. The results proved to be in good agreement overall

Enhanced search methods for finding and identifying radioactive material for on-site inspection deployment

The CTBTO verification system comprises an On-Site Inspection (OSI) to verify the suspicion of a banned nuclear test. An OSI comprises different methods of verification, one of them being the radiological survey of the inspection area. The radiological survey is done by airborne survey, carborne survey, and environmental sampling, thereby narrowing the inspected area with each step. Our institute operates a measurement car DeGeN (German acronym for Detection of Gamma and Neutrons) with highly sensitive neutron and gamma detection systems. In the present study we investigated the influence of the human factor by investigating measurement results obtained by a larger group of test persons operating our measurement car DeGeN

Qualification setup for systems for measuring nuclear and radioactive material: Paper presented at INMM 2018, 59th Annual Meeting Institute of Nuclear Materials Management, July 22-26, 2018, Baltimore, Maryland

In various types of application, systems for measuring nuclear and radioactive material are used. During the purchase decision-making process, the information given by the manufacturer will be taken into consideration. In other application are as several well established standards exist which have to be fulfilled and in relation to which the devices are tested in qualified laboratories. In the field of measurement systems for nuclear and radioactive material no test laboratories in Europe were established for this kind of devices yet. In the Illicit Trafficking Radiation Detection Assessment Program + 10 (ITRAP+10) dedicated testing procedures, test equipment and test methods have been developed based on ANSI and IEC standards. The corresponding tests have been performed at the European Joint ResearchCentre (JRC) in Ispra (Italy) and in several national labs in the US. The next step is to enable laboratories in Europe to verify an instrument’s compliance to these standards. This is currently carried out in ITRAP+10 Phase II in work package 2. The Fraunhofer INT is one of the participating organizations and has conceived and built a test environment to perform the corresponding dynamic and static test measurements using neutron and gamma sources. This paper deals with the development of the testing facility at Fraunhofer INT consisting of a guide rail system with roller carriages carrying the measurement systems. A lifting device controlled with pressurized air lifts the radioactive sources from inside a shielding case up to a position in front of the measurement systems. The system is completed by a data acquisition system which includes video data collection. This enables the analysis of the time response even for systems without data storage capabilities. The setup is quite flexible and offers many options. The development phase as well as first experience with the system and first investigations of measurement systems are presented

Comparative testing of the MCA-527 and MCA-166 mini multi channel analysers

This paper presents a comparative study of the two multichannel analysers MCA-166 and its successor the MCA-527 from GBS electronic with the focus of the operation at high counting rates. The MCA-166 is widely used by the IAEA and Euratom for safeguards inspections in the field. The performed tests included the influence of peak shaping parameters, count rate and temperature on the operation of the two multichannel analysers

Study of neutron detection technologies using ⁶Li as a replacement of ³He: Paper presented at INMM 2017, 58th Annual Meeting Institute of Nuclear Materials Management, July 2017, Indian Wells

Within the past decade a significant shortage of ³He has occurred. Since this material is widely used in neutron detection applications, e.g. by first responders, during on-site inspections, and in safeguard applications where nuclear and radioactive material has to be localized and possibly identified, replacement materials need to be considered, selected, implemented in a corresponding detector, and thoroughly tested. One of these promising materials is ⁶Li which is utilized in detector applications such as ⁶LiF/ZnS, CLYC (Cs₂LiYCl₆:Ce), and CLLB (Cs₂LiLaBr₆:Ce). The latter two detector types even offer the possibility of measuring gamma radiation simultaneously with good discrimination capability between neutrons and gammas. Within the detection materials neutrons are captured by ⁶Li, triggering the nuclear reaction ⁶Li(n,t)α. The secondary particles then create light pulses in the scintillation crystal which ultimately serve as detection signals. Due to the large Q-value of the reaction of 4.78 MeV, the signals are of the same order of magnitude as those of high energetic gamma photons. The discrimination of neutron and gamma radiation can be realized by pulse shape analysis. Measurements with all detector types mentioned above have been performed. We have verified these detectors’ capabilities with measurements of several neutron sources, also compared to a detector filled with ³He. The possibility of detecting such a (hidden and/or shielded) source which creates a radiation field only slightly above the background radiation level is of particular interest. Other figures of interest were the FWHM (full width at half maximum) of the CLYC and CLLB gamma spectra and the detectors’ efficiencies, especially with regard to a detector with ³He tubes. The results of these verification tests will serve as supportive information for first responders and other experts who work in the field of nuclear safety and security regarding suitable neutron detection materials without the rare ³He