ՃԱՌԱԳԱՅԹԱՅԻՆ ԱՆՎՏԱՆԳՈՒԹՅՈՒՆ ԵՎ ՊԱՇՏՊԱՆՈՒԹՅՈՒՆ

Radiation Safety Group’s expertise covers the areas of radiation safety, radiation protection and security. The group’s activities are:

• γ-spectrometry,
• X-ray testing and quality control,
• workplace and source monitoring,
• radiation protection and shielding calculations,
• radiological consequence assessment of radionuclides released to the environment,
• security systems’ assessment and upgrade in the organizations using ionizing radiation sources,
• personal radiation monitoring,
• environmental monitoring,
• assessment of radioactive waste safe management practice, and
• training in the field of radiation safety and protection.

The Radiation Safety Group is able to develop regulatory documents, procedures and guides on radiation safety and radiation protection, on security of ionizing radiation sources, and on radioactive waste management.

The Application of γ-spectrometry

For gamma emitter identification and activity measurements γ-spectrometry is considered one of the best and indispensable methods. In addition, γ-spectrometry is the key methodology for the non-destructive assay (NDA) of nuclear materials. Together with other non-destructive and destructive analytical methods, γ-spectrometry is widely used in nuclear forensics.

The Radiation Safety Group uses γ-spectrometry for various activities such as identification of orphan ionizing radiation sources, regulatory inspection, nuclear forensics investigations and so on. For γ-spectrometry the NRSC uses Inspector1000, Identifinder2-HM5, MKS-ATTAS-scanner hand held NaI scintillators, and ORTEX TRANSPEC high efficiency HPGe semiconductor stationary fixed detector with electromechanical cooling system.

The picture shows containers made of depleted uranium found in the framework of Orphan Sources Search Program.

Emergency response to Radiation Events

The NRSC mobile group is equipped to perform quick dose rate measurements, sampling, and qualitative and quantitative measurements of radionuclide’s content in samples from the environment. The mobile group assists to determine whether the population and staff are at risk of possible contamination during emergency situations or not. The group is equipped with special equipment for field measurements. It also uses protective clothing during emergency response activities.

The picture shows the scene during emergency response measurements at the customs’ check point.

Quality control, Workplace and Source monitoring, X-ray Testing

Many ionizing radiation sources such as 60Co, 241Am, 90Sr, 137Cs, 131I, 192Ir and ionizing radiation generators such as X-ray tubes, particle accelerators, Mo-Tc generators are widely used in industry and in scientific and medical applications. As a rule, all actions related to ionizing radiation sources and generators must be clearly justified: they may create hazards for people and environment. From this viewpoint, safety justification must be based on radiation sources’ and ionizing radiation generators’ testing, quality control, workplace and source monitoring results. According to existing legislation, equipment testing, quality control, workplace and source monitoring must be performed periodically. As technical support to regulatory inspections conducted in the industrial, medical, scientific and technical organizations, the Radiation Safety Group organizes and conducts various radiological measurements, namely:

• quality control of X-ray and radio diagnostic/therapeutic equipment, and long term stability testing;
• quality control of equipment containing radiation sources and generators used in the industry, and in scientific and technical applications;
• workplace monitoring in the facilities using ionizing radiation sources and generators.

For workplace monitoring, X-ray and radio diagnostic/therapeutic equipment quality control and long term stability testing Unfors Xi, body equivalent phantom, Radiagem 2000, E600, Inspector1000, IdentiFinder2-HM5 and RedEye PRD are used.

Radiation Protection and shielding Calculations

Radiation protection and shielding calculations are necessary for radiation safety justification, consequently, radiation safety assessment must certainly perform radiation protection and shielding calculations. In light of this, Monte Carlo method is the most sophisticated method for protection and shielding calculation: it is based on ionizing radiation and material interaction phenomenon. In addition, there are several computer codes specifically developed for protection and shielding calculations that use Monte Carlo simulation and attenuation coefficients that, in turn, depend on photon and particle energies.

The Radiation Safety Group had developed the methodology for protection and shielding calculations for workplaces in which X-ray equipment is installed. As well, for radiation protection and shielding calculations the Radiation Safety Group used MercuRad code and another code based on MCNP Monte Carlo method: MercuRad code allows to simulate sources with certain geometry.

3D model for dose rate calculation developed by MercuRad code

Radiological Consequences Assessment of Radionuclides released to the Environment

The radiological consequence assessment of radionuclide’s release to the environment during accidents and during normal operation of nuclear installations are very important tasks in justification of safety of nuclear installations. Radiological consequence assessment is based on a specific source term, meteorological conditions, geographical terrain features, population and other factors. The assessment must take into account the external and internal exposure pathways such as the typical foodstuff of the population, cloud shine, deposition and remediation.

There are several computer codes for radiological consequence assessment of radionuclide’s release to the environment. To successfully perform these assessments, the Radiation Safety Group closely cooperates with the Thermal Hydraulic Group. And in relation to this, RADTRAD, RASCAL and PUMA codes are used as the main tools for radiological consequence analysis.

Assessment and Upgrade of Security Systems at Organizations using Ionizing Radiation Sources

All facilities that are using or storing ionizing radiation sources must have appropriate physical protection system. The physical protection system must be in tune with the categories of the sources and threat assessment. A graded approach is applied as well.

The Radiation Safety Group is experienced to assess and upgrade the security systems of organizations that use ionizing radiation sources. To carry out stepwise upgrades of physical protection systems of the RADON facility and to upgrade security systems of National Oncological Center, Institute of Physical Research of National Academy of Science of Armenia and Gyumri Oncological Center, the Radiation Safety Group started to cooperate with US Pacific Northwest National Laboratory from the year 2009. Now all these organization had well developed security systems equipped with modern video cameras, biometric access devices, area radiation monitors, motion detectors, strobe combination sirens, and alarm management systems.

Personal Radiation Monitoring

According to Armenian regulations all staff members of Category A and B are required to be covered by Personal Radiation Monitoring Program per quarter. And all those organizations that deal with ionizing radiation sources are responsible for Category A and B staff’s radiation monitoring. The NRSC laboratory is equipped to conduct passive radiation monitoring. Particularly, the HARSHAW4500 system, which uses TLD’s, is installed and used for individual radiation monitoring, and about 200 people annually are monitored in the NRSC laboratory. The NRSC laboratory provides quarterly and annual reports on absorbed radiation of each individual and is obligated to store this information for the next 50 years: each individual is also provided with exposure passports. In addition, the HARSHAW4500 dosimetric system is annually calibrated by Calibration Dosimeters which, in turn, are irradiated and calibrated in the IAEA Dosimetry Laboratory in Austria.

Environmental Radiation Monitoring

According to Armenian legislation, facilities are responsible to carry out the environmental radiation monitoring on the site. The Armenian Nuclear Regulatory Authority is responsible for the environmental radiation monitoring outside of the site (observation area) of nuclear facilities. According to IAEA recommendations, environmental radiation monitoring can be carried out by early warning systems equipped with gamma dose rate monitors and spectrometers, mobile systems equipped with different radiometers and sampling systems, and by passive dosimetric systems. The environmental radiation monitoring system beyond nuclear facility’s observation areas is on the early stages of development in Armenia; the monitoring plan is currently developed. And, as a preliminary stage of comprehensive environmental radiation monitoring system establishment, the mobile team of Radiation Safety Group conducted radon monitoring activities in densely populated areas.

During the last few years, the mobile team of Radiation Safety Group carried out environmental radiation monitoring in 11 organizations (in metal scrub collecting facilities and in several mines) that do not constitute a significant threat to environment: the background gamma dose rate and the gamma spectrum were measured. Soil samples were also taken.

Assessment of Radioactive waste management Practice

The safe management of radioactive waste is the final process in handling of nuclear materials, radioactive sources and other substances, which contain or are contaminated with radionuclides. The radioactive waste management includes waste conditioning/processing and long term storage. There are two authorized organizations for radiation waste management in Armenia: the Armenian Nuclear Power Plant and the Radioactive Waste Facility (RADON).

The Radiation Safety Group is actively involved in assessment of radioactive waste management activities in Armenia. The Radiation Safety Group is experienced to develop and review the regulatory documents, procedures and guides, as well as safety justifications of radioactive waste management.

A special radioactive source and waste transportation vehicle that belongs to RADON facility.

Trainings on Radiation Safety and Protection

The NRSC organizes regular trainings and workshops for specialists and new-comers from local and foreign organizations. The NRSC has years of experience in organizing and conducting basic and advanced trainings for specialists in the field of nuclear and radiation safety. The NRSC organizes trainings for representatives from industrial and medical facilities that use ionizing radiation sources. Over the last 3 years, the Radiation Safety Group has organized and conducted more than 10 trainings and workshops related to radiation security and radioactive waste transportation within the framework of US Assistance Program. In addition, the Radiation Safety Group participates in regular seminars for Advanced Regulatory Information System (ARIS) users.

Seminar for the ARIS users

Materials prepared by the NRSC for the security training