On Site Radiometric Categorization of Nuclear Material by Gamma Spectrometry. First Results. Field Exercise Designed for Training of Law Enforcement Agents

Since entry into force of the Amendment to the Convention on the Physical Protection of Nuclear Material (CPPNM) [1] and in concordance with UN 1540 resolution [2], each State has the responsibility for the establishment, implementation and maintenance of a physical protection regime of nuclear material. In order to establish control of the nuclear material (even during transport), the State may provide the tools and specific knowledge to the law enforcement agents for detecting, characterizing and controlling the presence of nuclear material out of the regulatory control as soon as possible. The paper is focused on how to improve the information that law enforcement agents obtain on site using their equipment for the detection and characterization of nuclear material. Almost all countries have special teams in the law enforcement corps as first responders against CBRN attacks. These forces always have as a part of their technical equipment a gamma spectrometry portable device for detection and measuring any dose rate and/or the presence of contamination. One typical scenario for the law enforcement agents (i.e., customs control, security control, inspection of any industry or facility) is where they have to detect the presence of nuclear material using this type of gamma spectrometry devices, which raises several issues. First, is it possible to detect nuclear material using gamma spectrometry devices? Although U, Pu and Th are alpha emitters, law enforcement agents also need to know that they have gamma emission as well and due to alpha decay and the presence of emission of gamma daughter isotopes is possible to detect. Second, in case of U nuclear material, is it possible to distinguish between mineral U, processed U, depleted U and or material enriched in ²³⁵U? Based on aforementioned issues, this work presents the first results obtained in CIEMAT by the close collaboration with the Spanish law enforcement corps. The centre of CIEMAT in Madrid is a nuclear facility since 1950's, ab initio as the headquarters of the JEN (Nuclear Energy Board) where the main activities carried out were related to the development of the nuclear fuel close cycle in Spain. Until 1970's the uranium extraction process from the minerals of different Spanish mines was done. The process of purification of the mineral consisted of partitioning it from the rest of the components of the matrix by physical and chemical methods, obtaining concentrates of U [3] [4]. In addition, in the former JEN, nuclear fuel manufacturing processes (pyro and hydrometallurgical extraction process) were also carried out, including the enrichment stage for use in nuclear reactors, and the fuel cycle was closed with a reprocessing plant that stopped working at 1973. This background allows to have different small amounts of U nuclear material that can be used for radiochemical measurements using gamma spectrometry portable devices.