From 8 to 12 July 2013 the State Nuclear Regulatory Inspectorate of Ukraine under assistance of the U.S. Department of Energy carried out a training on search and retrieval of orphan radiation sources (hereinafter – Training). The event was held at George Kusmycz Training Center for Physical Protection, Control and Accounting of Nuclear Material of the Kyiv Nuclear Research Institute of the National Academy of Sciences of Ukraine, with the participation of experts from the Argonne National Laboratory, State Border Guard Service Administration, Regional Departments of Civil Protection, Radon State Corporation, State Scientific and Technical Center for Nuclear and Radiation Safety, State Quality Center, and representatives of other organizations to be involved in the search of orphan IRS in Ukraine. The Training was carried out within a global treat reduction initiative (GTRI).
Actually, the program purpose is to train partners in the search, identification, packaging, transportation and disposal of orphan ionizing radiation sources (hereinafter – IRS). The program started in 2004 under cooperation with the International Atomic Energy Agency (IAEA) (draft RER 9-073). Currently, under this project more than 50 countries were supported, more than 900 people were trained, thousands of orphan radioactive sources were detected and deactivated. The project organizers provide equipment (suitable for use in buildings, underground structures, as well as for detection of highly secure IRS), train listeners (theoretical and practical work in the classroom, as well as field training) and other GTRI measures. The Training consists of several modules: verified inventory, arrangement of the search, search planning and procedure, work with devices to detect orphan IRS, unknown IRS description, IRS packaging and transportation, field training to detect orphan ionizing radiation sources. Other GTRI measures represent assistance on verified inventory, search of orphan IRS, safe storage of orphan IRS or removed from use, physical protection aspects. The training on the whole considered the problem of orphan IRS, brief description, basic principles of physical protection (detection, detain, response ), accidents related to orphan IRS (particularly, radiation accident in 1987 in Goiania, Brazil and “lethal finding” in December 2001 in a closed valley near the town of Leah, Georgia) and their consequences. Based on the information presented the main tasks were formed: IRS search and renewal of control over them by the regulatory authorities, protection of vulnerable IRS against theft, loss and abandonment.
Also attention was paid to safe work in the environments with possible presence of IRS; general information was presented on closed IRS categorization and their application areas. The trainees were familiarized with the methods for developing a program on orphan IRS search and deactivation by assessing the issue, forming an archive of objects, performing verified inventory, search planning. Among other, the trainers were provided with general information on radiation detection equipment divided into primary, secondary and auxiliary, which should be used only for the intended purpose depending on the search stage. In particular PackEye, Radiagem 2000 + SG-2R and Inspector 1000 belong to the main equipment, RadEye, Model 19 A to secondary, Radiagem 2000 Base Unit, Model 9-4 and TELE-STTC to auxiliary equipment. The trainers underlined that the main equipment is highly sensitive to gamma – and/or neutron radiation; it is used for the initial search within large areas, it provides the possibility to cover quickly large areas and can be fastened to a vehicle. The secondary search equipment is not as sensitive as the main. It should not be used in search as the main equipment. It is desirable to use it for search within small areas. Auxiliary equipment is rather not sensitive dosimeters of gamma radiation or radioactive contamination. They should not be used for the search. They are used to identify sources, evaluate activity (point sources) or control contamination.
Then the Argonne National Laboratory experts presented for the participants the structure, technical characteristics, external control components, standard functions, in-service inspection methods, peculiarities of practical application of the following devices: Model 19A (device for radiation dose measuring in microsievert), Model 9-4 (ionization chamber), RO-20 (ionization chamber), RadEye (PRD) (wide-range gamma-dosimeter), PackEye FTH 1377 (backpack), Radiagem 2000 (portable dosimeter) and contact detectors, TELE-STTC (telescopic detector to measure gamma-radiation with high dose rate), IN1KS-2 1000 Inspector with sodium iodine detector 2×2 IPROS-2 (portable scintillation gamma spectrometer), portable counter to test swipes (scaler/ratemeter, α-β sample counter).
Also, during the Training attention was paid to the IRS search rules the main constituents of which are search planning and search procedure development. Familiarization with the basis of closed IRS packaging and transportation was one of the final training stage. In particular, the following was considered:
- safe and correct packaging and transportation: rules, instructions, examples;
- requirements for packaging and transportation based on the data received during the field work;
- source storage: requirements for packaging.
An integral part of the transportation is information about the source (nuclide, activity, source/device form, dose rate). These data may be determined based on identification information at the place of use. Also in the event of searching orphan IRS the question arises on their packaging before further transportation. In this case, the procedure generally consists of several stages: processing of discovered sources at the place of use (identification, description, packaging and transport to storage facility), discussion of some issues (radiological protection and safety, data collection, selection of packaging).
An important Training stage was field training carried out to reinforce theoretical skills gained by the trainees during the study in search, retrieval, packaging and transportation of detected orphan IRS with the help of practical exercises. Prior to this event, students of the course were divided into two search groups, each of which chose a captain, whose responsibilities were to manage a group member actions, monitor compliance with jointly developed search strategies and coordinate their actions during the search. Also, each team member has a search device and relevant responsibilities in implementing the search stages. For each group inspection of two objects (A and B) located at the territory of NRI of the Academy of Sciences of Ukraine was planned, surveyed area plan was provided, and backstory of events preceded the current measures on the search of orphan IRS was described previously. Object A. Lost sources in research center. Backstory. After an in-depth historical study of groups and companies, which might use ionizing radiation sources, it was determined that lost sources could be detected at a closed facility of a company specialized in the copper production. According to the data received the company occupied the site and buildings in 1962-1986. Relevant inventory records were kept only for 70% of the sources used. After the company closure these sources were sold for processing. The remaining 30 % were unaccounted.
We also know that in addition to various research sources the company used many radioactive devices, radiometric density probes and sources for well testing. The source search group was proposed to search the sources in an old mine. Object B. Abandoned building complex. Backstory. A man came to editorial office of a local newspaper and said that according to the information he had orphan ionizing radiation sources were located in an abandoned scientific complex near his summer house. The man’ friend worked in this scientific complex and advised not to approach to the buildings. The applicant once drove by and saw the children playing in the building. That’s why he decided to come to editorial office of the local newspaper and warn of the danger. The source search team was called to survey the abandoned scientific complex. Its members should determine whether there were certain sources or not. Then, each team with one expert from the Argonne National Laboratory as an observer, surveyed these objects, ionizing radiation sources were detected and retrieved. After the event the search was discussed, team captains presented a detailed report on the work performed and number of detected sources, actions of the group members were discussed together, ways and methods of the search improvement and optimization in future were considered.
The event will contribute to personnel and environment radiation protection and allow the most efficient improvement of the state regulation system as regards orphan and vulnerable radioactive sources, as well as arrangement and carrying out the search of orphan IRS at the territory of Ukraine based on advanced European safety principles and practices.
Shevchenko Alexander – Chief Specialist-State Inspector, Division of Radiation Safety Technologies, Unit of Radiation Safety, State Nuclear Regulatory Inspectorate of Ukraine 4/10/2013