Environmental Radiology

Environmental Radiology is a field of science which studies the presence of ionizing radiation from various sources in the environment and how the radiation doses to humans and biota can be detected or described by means of measurement techniques and calculation methods. Development and improvement of methods and measurement techniques for the determination of ionizing radiation in the environment is therefore crucial. Over the next few years, we will have the following focus on our research programs in Environmental Radiology in Malmö.

 

Optically stimulated luminescence dosimetry - new methods and detectors for the determination of radiation doses

Using a technique called optical simulated luminescence (OSL), one can determine the amount of radiation a crystalline material have been exposed to. This technology is extensively used in geology and archeology since it allows age determinations of objects containing materials with crystalline structure. We are among the groups that also want to study how to use this technology for so-called retrospective dosimetry. Retrospective dosimetry is a term to describe the calculation of radiation doses to people or population groups after unintentional exposure of ionizing radiation (such as nuclear fallout, transport accidents, terrorist attacks, etc.).

Our research within retrospective dosimetry is directed to investigate the OSL-properties of different materials and to develop and optimize the OSL-technology for these materials. Examples of materials that have proven to be very useful for retrospective OSL-dosimetry are ordinary household salt, SIM cards, dental restorative materials and electronic components. The project group is also a member of a European collaboration network on retrospective dosimetry.

OSL is also the technique used in the development of a new type of dosimeter based on household salt. This dosimeter is a cheap and simple compliment to today’s passive dosimeters. Possible applications include radiology, nuclear medicine, the nuclear industry and environmental monitoring.

 

 

Evaluation of long-term consequences after nuclear accidents - field studies in affected areas in Eastern Europe

An important part of understanding radiological and nuclear accidents is to study past events. Since 1990, The research project group in Malmö has been involved in the work to understand, manage and mitigate the effects after the Chernobyl nuclear power plant accident in Chernobyl (1986). Through collaboration with various organizations, as the St Petersburg Research Institute of Radiation Hygiene named after Professor PV Ramzaev, St Petersburg (Russia), St. Petersburg, and the Chernobyl Committee Institute of Radiobiology, Minsk, Gomel, Belarus, the radiation situation and population exposure in some of the most heavily contaminated areas in Russia and Belarus have been examined and followed-up for several years.

Although the radiation level today, at most of these places, is comparable to the natural background radiation in Sweden, it is still important to continue to monitor the radiation situation in order to increase the understanding of the long-term consequences of a similar event in the future.

In combination with the surveys in the Chernobyl contaminated areas of Russia and Belarus, the retrospective OSL materials have been tested. These tests have been carried out and repeated in order to determine the usability of the OSL technique under realistic conditions outside the laboratory. Continued studies, both in the laboratory and in situ, are necessary to fully conclude on the potential of different OSL materials for retrospective- as well as prospective dosimetry.

 

 

Radioecological models - the study of transfer pathways of radioactive substances from contamination on the ground to humans and its radiological consequences

The project group in Malmö has been involved in a number of national projects in radioecological transport routes to various bioindicators (organisms with particularly high uptake of radionuclides) and different population groups. In the middle of the 2000s the project group was commissioned by the National Radiation Safety Authority to compile an exhaustive database of whole-body burden measurements of adults in Sweden, which could be a base for current and future studies of the radiation environment.

This database is now used in several studies on the internal and external exposure to Chernobyl ¹³⁷Cs in critical groups in terms of radioecological transfer. A model that sums both the external and internal exposure pathways to humans has now been developed that can be used to estimate the long-term radiological consequences from a nuclear plant release. The model has been found to agree well with findings from Russia after the Chernobyl fallout, and it will also be adapted to accommodate more general type of NPP-releases, such as the one from the Fukushima in 2011.

Together with Gothenburg University and Occupational and Environmental Medicine at Uppsala University the elaboration of this model is continued, and the next step is to estimate collective doses to Swedish populations, and to hunters, which exhibit a more than three times higher transfer of radiocesium than the general population. Furthermore, a joint Nordic project (financed by the NKS) has been launched together with Gothenburg University where whole-body burden data of radiocesium in man from other Nordic countries are compiled.

 

Maintain and increase the competence - develop training programs and courses in radiation protection for experts, medical physicists, instructors and other stakeholders

The research group has since the mid-2000s been engaged in developing a number of national training and exercise packages in the field of radiation protection and emergency preparedness. These courses have been designed in cooperation with the department of Medical Radiation Physics at Gothenburg University. The ambition has been to strengthen the skills of the staff that are directly involved in the event of a nuclear accident or a radiological-/nuclear emergency situation. Therefore, several different types of courses and exercises have been designed, based on the profession and the professional level of the participants; one part is a specialized course package (four courses) for medical radiation physicists that have been held since 2006.

In addition to this, practical exercises with detector systems and sources in the field have been held since 2007. These courses have been open for a number of professions in addition to radiation physicists, such as physicians, nurses, emergency rescue workers, police, and customs officials. The courses have provided unique opportunities to practice collaboration between these categories in the first response to a radiological or nuclear emergency. In autumn of 2012 a Master degree program was launched together with Gothenburg University, where the aforementioned courses and exercises are included. The admission to this Master Programme is via the Sahlgrenska Academy in Gothenburg. More information about the master's degree program is given on:

 https://radfys.gu.se/utbildning/Kurser+i+str%C3%A5lskydd/Masterexamen.

The research group also intends to join a national network SAINT (Swedish Academic Initiative on Nuclear and radiation Technology research and education) launched by Chalmers Technical University AB.  The aim is to consolidate teaching materials and efforts within the network to provide with a more extensive package of courses directed towards both advanced levels and for professional development within the nuclear industry.

 

 

Internal dosimetry - uptake and metabolism of radionuclides in humans

This area of research can be viewed as a link between environmental radiology and radiation protection in medicine. We have studied the behavior of different radionuclides in the human body, especially radionuclides associated with the operation of nuclear power plants (⁶⁰Co and ⁵⁸Co) or associated with nuclear accidents (¹³⁴Cs and ¹³⁷Cs). Radioactive cobalt (e.g. ⁶⁰Co and ⁵⁸Co) is common as a neutron activated corrosion product generated in the nuclear reactor plant and can also disperse to the surrounding environment due to operational releases.

Strong sources of radioactive cobalt used for radiotherapy and sterilization can also be found in connection with a transportation accident, or terrorist event using these sources, and can then be spread to a large number of individuals. To calculate the effective dose for contaminated persons it is necessary to have knowledge on the retention of the cobalt in the human body in terms of residence times in the different organs and excretion routes. In one biokinetic study in human volunteers we have examined the metabolism and distribution of ⁵⁷Co and ⁵⁸Co. These studies are performed on human volunteers who ingested radioactive cobalt by inhalation or orally.

Furthermore, studies on the alpha emitter ²¹⁰Po in hair and feces have been performed to estimate the gastrointestinal uptake of the radionuclide. ²¹⁰Po is, next to ⁴⁰K, the naturally occurring radionuclide resulting in the highest radiation exposures to humans, but it can also be used as a poison and other malicious acts. An investigation was done some years ago where hair was studied as an indicator of past intakes of ²¹⁰Po that can be used to identify whether the individual has been subject to abnormal intakes of the radionuclide.

Currently studies have been launched directed towards the potential radionuclides being released during the operation of the European Spallation Source (ESS). In a co-operation with Division of Nuclear Physics at Lund University a study on the urinary excretion of tritium in three different groups around the ESS-site has been done; ESS-workers, non-ESS workers whose work entails handling of tritium, and a reference group representing the general population. Furthermore, calibration geometries using high-resolution gamma spectrometry has been developed to study the occupational internal doses among ESS-workers before the site is in operation in order to obtain a baseline for future assessments.

 

ESS

In a collaboration project between Medical Radiation Physics Malmö and the Division of Nuclear Physics at Lund University, we have carried out a large-scale survey program of the radiation environment around the European Spallation Source (ESS). The aim was to establish the current levels of ionizing radiation and concentration of various radionuclides, natural as well as artificial, in the surroundings of ESS prior to start of operation of the facility. The data generated, during 2017-2018, may be used to determine future potentially unobserved and diffuse discharges from ESS to the environment. Such comparisons can also provide information of possible long-term changes in the radionuclide concentrations in the environment as well as assessments of the exposure to the public before and after operation of ESS. 

The report “assessment of zero point radiation around the ESS facility” can be found at: https://portal.research.lu.se/portal/sv/publications/assessment-of-zero-point-radiation-around-the-ess-facility(2153e07c-b465-4191-abc3-dbfcaf28b85b).html

A folder summarising the measurements, were distributed to the public around ESS. That folder may be found at: www.med.lu.se/msf

The monitoring program should continue for longer time periods in order to include seasonal variations in the radiation environment and radionuclide concentrations and uptakes. 

 

Mobile gamma spectrometry – locate, identify and handling lost sources

Medical Radiation Physics in Malmö has two vehicles with dedicated measurement equipment for ionizing radiation; a car and a trailer. These two vehicles are constantly on alert. In cases where individuals, businesses or society need help with a radiological incident or support in a situation that requires expert help, this is one of the resources that can be sent out on the spot. We also have measuring devices that can be placed in e.g. rental cars, for rapid and extended efforts where necessary. We also provide expertise for the proper handling of the sources found. There are several active research projects in the area, mainly in developing systems and methods for displaying, identification, activity determination and calculation of the absorbed dose from the series of measurements that can be made with the portable systems.

 

Emergency preparedness laboratory – a network over Sweden connected to the Swedish Radiation Safety Authority

Our research group has been assigned by the Swedish Radiation Safety Authority (SSM) to aid in their effort to protect the public in case of a radiological or nuclear emergency. The aid consists in providing competence and appointed laboratory resources, and to maintain specified emergency methods for assessing the radiological situation. The research group is part of the national network of laboratories and will be used to provide support of measurements and on decision making for population protection.

The laboratory in Malmö has a large infrastructure of detectors for gamma spectrometry both in laboratory environment and for field use, but we also have the ability to perform determination of alpha- and beta emitting radionuclides in a variety of sample matrices. A low background facility, which is also used for clinical measurements, has capacity to measure the whole-body contents of internally contaminated persons (including cesium and iodine down to very low levels below 50 Bq). With the recent calibration using a high-resolution HPGe-detector, the laboratory also has resources to detect radionuclides that could be emitted in case of release from the ESS-site, such as ¹⁷²Hf and ¹⁸²Ta. We focus on efficiency and our aim is to be in the front line in development and research to make quality field measurements in radiation emergency situations. Our detector systems are used for research and we continuously take part in international comparisons (e.g. the IAEA laboratory proficiency test).

 

Maintaining the expertise - radiation exercises for the Swedish radiation preparedness organization

Through the close cooperation with SSM, Medical Radiation Physics in Malmö has been commissioned to organize annual training (theoretical and practical) for the entire Swedish radiation preparedness organization. In these exercises we are training radiation protection specialist together with other relevant authorities, such as the Armed Forces, other Swedish preparedness laboratories, FOI, SkyddC in Umeå, Swedish customs, The Swedish contingency, police and others. The Danish Emergency Management Agency (DEMA) has been contracting the Lund University laboratory to help develop two courses to educate their measurement teams in field operative measurements in case of radiation emergencies and accidents. Our future aim is to continue to help other authorities and countries to train and develop their radiation emergency capabilities.

 

Alpha Spectroscopy and Radiochemistry

Alpha-emitting radionuclides are present in the environment naturally or after releases from human activities. Medical Radiation Physics Malmö has a long experience of analysis of alpha-emitters traces by alpha-spectroscopy. Due to the low amount of radioactive material and interferences between radionuclides, samples usually require to be chemically purified and pre-concentrated. After separation, the alpha-emitters are deposed on metal discs by electrolysis and analyzed by alpha spectrometry.

Our group owns eight surface barrier alpha detectors in vacuum chambers as well as a radiochemistry laboratory dedicated to chemical separation and source preparation. We also have the expertise to develop sample preparation methods fitting the analysis of any long-lived alpha emitters of interest in water, soil or organic samples.

Our current projects involve the analysis of plutonium in peat bog samples from Madagascar and the analysis of actinide traces in seaweeds from the Swedish coast.

 

Monte Carlo simulations

The Monte Carlo method is a numerical experiment and is applied here for dosimetry and radiation protection purposes. The employed code follows a particle that represents gamma radiation, from its source throughout its life, in which it might interact with matter, till its death, which could be absorption through matter or escaping the boundaries of the described model. The basic principle of the Monte Carlo method is the random selection of physical parameters according to given distributions that depend on the characteristics of materials as well as the energy, direction, and position of the radiation. The results are obtained by averaging over the scores of all particles with their paths and interaction histories that were calculated for the respective source and thus accompanied by statistical uncertainty. Therefore, Monte Carlo simulations require lots of computing power, but also offer a wide range of applications e.g. in testing ideas before putting them into practice.