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[en] Attribute measurement systems (AMS) are designed to measure potentially sensitive items containing Special Nuclear Materials to determine if the items possess attributes which fall within an agreed-upon range. Such systems could be used in a treaty to inspect and verify the identity of items in storage without revealing any sensitive information associated with the item. An AMS needs to satisfy two constraints: the host party needs to be sure that none of their sensitive information is released, while the inspecting party wants to have confidence that the limited amount of information they see accurately reflects the properties of the item being measured. The former involves 'certifying' the system and the latter 'authenticating' it. Previous work into designing and building AMS systems have focused more on the questions of certifiability than on the questions of authentication - although a few approaches have been investigated. The next step is to build a 3rd generation AMS which (1) makes the appropriate measurements, (2) can be certified, and (3) can be authenticated (the three generations). This paper will discuss the ideas, options, and process of producing a design for a 3rd generation AMS.
[en] This paper, which is limited to essentially dry solid systems where the majority of fissionable material has already been removed, discusses the bases for and features of a graded approach criticality safety program in which criticality can be documented not to be credible under all normal and all credible abnormal conditions. (authors)
[en] A pulsed photonuclear interrogation environment is rich with time-dependent, material specific, radiation signatures. Exploitation of these signatures in the delayed time regime (>1us after the photon flash) has been explored through various detection schemes to identify both shielded nuclear material and nitrogen-based explosives. Prompt emission may also be invaluable for these detection methods. Numerical and experimental results, which utilize specially modified neutron and HpGe detectors, are presented which illustrate the efficacy of utilizing these time-dependent signatures. Optimal selection of the appropriate delayed time window is essential to these pulsed inspection systems. For explosive (ANFO surrogate) detection, both numerical models and experimental results illustrate that nearly all 14N(n,y) reactions have occurred within l00 us after the flash. In contrast, however, gamma-ray and neutron signals for nuclear material detection require a delay of several milliseconds after the photon pulse. In this case, any data collected too close to the photon flash results in a spectrum dominated by high energy signals which make it difficult to discern signatures from nuclear material. Specifically, two short-lived, high-energy fission fragments (97Ag(T1/2=5.1 s) and 94Sr(T1/2=75.2 s)) were measured and identified as indicators of the presence of fissionable material. These developments demonstrate that a photon inspection environment can be exploited for time-dependent, material specific signatures through the proper operation of specially modified detectors
[en] In a continuing effort to examine portable methods for implementing active neutron interrogation for detecting shielded fissionable material research is underway to investigate the utility of analyzing multiple time-correlated signatures. Time correlation refers here to the existence of unique characteristics of the fission interrogation signature related to the start and end of an irradiation, as well as signatures present in between individual pulses of an irradiating source. Traditional measurement approaches in this area have typically worked to detect die-away neutrons after the end of each pulse, neutrons in between pulses related to the decay of neutron emitting fission products, or neutrons or gamma rays related to the decay of neutron emitting fission products after the end of an irradiation exposure. In this paper we discus the potential weaknesses of assessing only one signature versus multiple signatures and make the assertion that multiple complimentary and orthogonal measurements should be used to bolster the performance of active interrogation systems, helping to minimize susceptibility to the weaknesses of individual signatures on their own. Recognizing that the problem of detection is a problem of low count rates, we are exploring methods to integrate commonly used signatures with rarely used signatures to improve detection capabilities for these measurements. In this paper we will discuss initial activity in this area with this approach together with observations of some of the strengths and weaknesses of using these different signatures.
[en] The system of radioactive and nuclear materials transportation in the Russian Federation is considered. Rigid requirements to transportation of such materials were established in the 50-s years of the last century and continue to be improved. Legal aspects, questions of interaction between the organizations transporting nuclear and radioactive materials and supervisory authorities are also considered
[ru]Рассмотрена система транспортирования радиоактивных и ядерных материалов в Российской Федерации. Жесткие требования к транспортированию таких материалов были заложены еще в 50-х годах прошлого века и продолжают совершенствоваться. Рассматриваются также правовые аспекты, вопросы взаимодействия между организациями, транспортирующими ядерные и радиоактивные материалы, и контролирующими органами
[en] A fast and robust methodology for identification of radioactive materials is of great interest for applications in the fields of homeland security and nuclear nonproliferation. For fissile materials in particular, several passive and active interrogation techniques are being investigated. These systems rely on the fact that the interrogated material emits correlated neutrons and gamma rays from each induced or spontaneous fission event. A convenient way to look at correlated events in a fissionable material is to study time-dependent detector cross-correlation functions. These functions are unique for a given material and geometry, representing a distinctive signature of the material-geometry configuration. In this work, we focus on the identification of plutonium samples in both metallic and oxide form. The simulation program used in this study is the MCNP-PoliMi code, an improved version of the standard MCNP code. This code allows the user to obtain event-by-event information about the simulated particles. This capability is essential for accurate simulations of cross-correlation events. The number of correlated events as a function of time is obtained from the MCNP-PoliMi output collision file by using appropriate post-processing algorithms. We investigated several parameters, such as the sample composition and mass, the sample-detector distance, and the shielding between the detector and the sample. We then analyzed the simulated cross correlation functions to obtain relationships between features from the correlations and sample characteristics. To verify the simulations, the measured correlation function was compared with the simulated one
[en] Development of atomic power engineering requires intensive NFC power increasing, but using modern technologies fast expense of nature raw materials is happened. Fast development will be possible only under building of new generation reactors - reactors with high reproduction of fission materials using as uranium and thorium raw materials.The problem of thorium reactors startup is in absence of natural fission nuclides in thorium. Argument of possibility of such reactor startup without involvement of fast reactors technologies will increase attention on such thermal reactors. Process of accumulation of fission materials in reactor fuel on thermal neutrons operating in closed coupled uranium-thorium fuel cycle is examined. Five variants of reactor initial loading differed by technology of used fission materials production are worked out. Possibility of tested reactor variants startup is shown. Time of fission components in fuel starting composition is selected.(author)
[en] This study aims to know the way of the ratio fission width (Γf)to total width (Γf) for compound nuclei of fission materials, when it had been bombarded by monoenergetic neutrons (2.4MeV) as a function of nuclear radius and ranges (1-10)*10-13 cm, and it concluded the mathematical equations that can be used for this way of the study.Also we concluded the empirical relations by fitting method in which the ratio fission width to the total width for monoenergetic neutrons (2.4MeV) for various fission nucleuses, for Uranium-238 and Thorium-232 respectively
[en] Full text: Implementation of international nuclear safeguards has changed considerably over the past 15 years. Early detection of undeclared facilities, activities and materials requires new approaches, supplemented by technologies that differ significantly from those used traditionally for on-site verification. In this framework, the project Novel Techniques and Instruments for Detection of Undeclared Nuclear Materials and Activities was established within the Department of Safeguards to identify specific needs in this area and to initiate the necessary research and development of techniques and instruments that will be used for the implementation of additional protocols, including the conduct of complementary access. Techniques, based on the detection of emanations associated with nuclear processes, are being investigated. These include the sampling and monitoring of specific solid, liquid and gaseous materials to provide new methods and approaches for the detection of undeclared nuclear activities from distances ranging from hundreds of metres to many kilometres. For example, laser-based methods have demonstrated real-time monitoring of atmospheric materials, on-site chemical analysis and the capability of detecting a previous exposure to ionizing radiation. On the basis of IAEA priorities and resources, a limited number of projects have been selected and cooperation with Member States has been initiated to take technologies to the maturity level needed for the use in field. This paper will introduce the novel technologies project and describe some of the techniques and instruments currently under consideration by the Department of Safeguards for the detection of undeclared nuclear materials and activities. (author)