[en] The general scientific policy objectives of the 12th International Congress of the International Radiation Protection Association (IRPA12) were the following: -To encourage all participants to put into practice its motto: 'strengthening radiation protection worldwide'. IRPA12 focused on the promotion, enhancement and strengthening of radiation protection worldwide through a broad gathering of professionals, rather than through a highly specialized conference aimed at reporting sharp scientific breakthroughs; -To produce a definite outcome, namely concrete findings and follow-up recommendations that can be implemented. To attain these general policy objectives, IRPA12 was arranged in three distinct Main Fields, which were divided into 10 Scientific Areas including a total of 38 Topical Sessions. The three main fields of radiation protection as follows: -Epistemological basis of radiation protection, namely current knowledge of the physics and biology of radiation exposure and its effects, particularly in relation to its scope experimental methods and theoretical validity; -Paradigm of radiation protection, namely universal conceptual models used to protect people from deleterious health effects due to radiation exposure; -Radiation protection in practice, namely the actual application and use of radiation protection plans and methodologies by practitioners and industries making use of radiation. For each main field, a background session was held, which provided the status of information on major international issues in these three fields. The keynote addresses held at these background sessions are included in this publication. Within the above main fields, IRPA12 focused on 10 Scientific Areas as follows: characterization of radiation exposure; biological effects of radiation; developing the radiation protection framework; developing protection policies, criteria, methods and culture; emergency planning, preparedness and response; radiation safety in nuclear installations; non-ionizing radiation applications; medicine; natural occurring radioactive material in industry; other applications and practices

[en] The general scientific policy objectives of the 12th International Congress of the International Radiation Protection Association (IRPA12) were the following: - To encourage all participants to put into practice its motto: 'strengthening radiation protection worldwide'. IRPA12 focused on the promotion, enhancement and strengthening of radiation protection worldwide through a broad gathering of professionals, rather than through a highly specialized conference aimed at reporting sharp scientific breakthroughs; - To produce a definite outcome, namely concrete findings and follow-up recommendations that can be implemented. To attain these general policy objectives, IRPA12 was arranged in three distinct Main Fields, which were divided into 10 Scientific Areas including a total of 38 Topical Sessions. The three main fields of radiation protection as follows: -Epistemological basis of radiation protection, namely current knowledge of the physics and biology of radiation exposure and its effects, particularly in relation to its scope experimental methods and theoretical validity; - Paradigm of radiation protection, namely universal conceptual models used to protect people from deleterious health effects due to radiation exposure; - Radiation protection in practice, namely the actual application and use of radiation protection plans and methodologies by practitioners and industries making use of radiation. For each main field, a background session was held, which provided the status of information on major international issues in these three fields. The keynote addresses held at these background sessions are included in this publication. Within the above main fields, IRPA12 focused on 10 Scientific Areas as follows: characterization of radiation exposure; biological effects of radiation; developing the radiation protection framework; developing protection policies, criteria, methods and culture; emergency planning, preparedness and response; radiation safety in nuclear installations; non-ionizing radiation applications; medicine; natural occurring radioactive material in industry; other applications and practices

[en] A Criticality Accident Alarm System (CAAS) was installed as part of criticality safety management for use in reducing the radiation workers could be exposed to in the rare case of a criticality accident. The initial CAAS version was installed the Tokai Reprocessing Plant (TRP) in the 1980s. It includes units that can detect gamma-rays or neutron-rays released in criticality accidents (CADs), one of which consists of three plastic scintillation gamma detectors and three solid state neutron detectors with fissile material, and in being highly reliable utilizes the 2 out of 3 voting system. The purpose of this study is to give the design principles and procedures for determining the adequate relocation of the CADs within the TRP. The optimal places for the CADs to be relocated to were determined using a conservative evaluation method. Firstly, equipment needing to be monitored for criticality accidents was selected with consideration given to the risk of excessive exposure to workers. Secondly, the detection threshold of a minimum accident was set to be an increase in power of 10¹⁵ fissions/s occurring within a rise-time of between 0.5 ms and 1 s. The sum of neutron and gamma doses of a minimum accident (10¹⁵ fissions) was 0.3 Gy at an unshielded distance of 1m. Finally, doses at where the CADs were installed were evaluated using parameters calculated with MCNP and ANISN. As a result, the alarm trip level of both the gamma detector and the neutron detector being set at 2.0 mGy/h enabled minimum criticality accidents to be conservatively detected. These results were then applied to the new CAD positions. (author)

[en] During a criticality accident, significant exposure is generated by 4 radiation origins: radiation directly induced by fissions (prompt neutrons and gamma), gamma radiations induced by (n, γ) reactions in crossed materials (capture gamma) and gamma radiations emitted by fission products. Due to boiling of the solution, a fraction of fissions products is airborne and is deposited in the ventilation shafts. 5.10¹⁸ fissions are considered in a dissolution tank containing uranyl nitrate by using the deterministic ATTILA radiation transport code. Instantaneous radiations rates are evaluated as a function of the distance and compared with data available in the literature. Dose rates induced behind various shielding materials such as concrete, steel or glass are assessed. In all cases, relative contributions of prompt or capture radiations is detailed. (author)

[en] People who have administrated radiopharmaceuticals could be a source of radiation to their relatives, medical nurses, and people who have contact them. In this study, the dose rates at various distances of 5, 10,50 and 100cm from 70 patients, who were administered diagnostic amounts of ²⁰¹Tl-Chloride and ^99mTc-MIBI, was measured using an ionization chamber. For determination of external radiation dose to the nurses the radiations in three deferent interval times have measured. The maximum values of external dose rates of ²⁰¹Tl and ^99mTc- MIBI were 11.2μSv/h ±2.3 and 43.1μSv/h ±11.9 respectively at 5cm from the patients. Significant exposure from patients after injection of ^99mTc-MIBI was limited on the day of administration. Departure doses rate of ²⁰¹Tl fell gradually so by 3 days after administration was significant. Maximum and average absorbed dose of nuclear medicine staff for one ²⁰¹Tl scan was 4.6 and 2.7μSv/h, and for ^99mTc-MIBI was 18.1 and 9.8μSv/h in a working day. (author)

[en] Anthropomorphic phantoms based on simple geometric structures have been used in radiation dose calculations for many years. We have now developed a series of anatomically realistic phantoms representing adults and children using body models based on non-uniform rational B-spline (NURBS), with organ and body masses based on the reference values given in ICRP Publication 89. Age-dependent models were scaled and shaped to represent the reference individuals described in ICRP 89 (male and female adults, newborns, 1-, 5-, 10- and 15-year-olds), using a software tool developed in Visual C++. Voxel-based versions of these models were used with GEANT4 radiation transport codes for calculation of specific absorbed fractions (SAFs) for internal sources of photons and electrons, using standard starting energy values. Organ masses in the models were within a few % of ICRP reference masses, and physicians reviewed the models for anatomical realism. Development of individual phantoms was much faster than manual segmentation of medical images, and resulted in a very uniform standardized phantom series. SAFs were calculated on the Vanderbilt multinode computing network (ACCRE). Photon and electron SAFs were calculated for all organs in all models, and were compared to values from similar phantoms developed by others. Agreement was very good in most cases; some differences were seen, due to differences in organ mass and geometry. This realistic phantom series represents a possible replacement for the Cristy/Eckerman series of the 1980's. Both phantom sets will be included in the next release of the OLINDA/EXM personal computer code, and the new phantoms will be made generally available to the research community for other uses. Calculated radiation doses for diagnostic and therapeutic radiopharmaceuticals will be compared with previous values. (author)

[en] This paper describes work carried out within the IAEA EMRAS program NORM working group to test the predictions of three computer models against measured radionuclide concentrations resulting from discharges from a lignite power plant complex. This complex consists of two power plants with a total of five discharge stacks, situated approximately 2-5 kilometres from a city of approximately 10,000 inhabitants. Monthly measurements of mean wind speed and direction, dust loading, and ²³⁸U activities in fallout samples, as well as mean annual values of ²³²Th activity in the nearest city sampling sites were available for the study. The models used in the study were PC-CREAM (a detailed impact assessment model), and COMPLY and CROM (screening models). In applying the models to this scenario it was noted that the meteorological data provided was not ideal for testing, and that a number of assumptions had to be made, particularly for the simpler models. However, taking the gaps and uncertainties in the data into account, the model predictions from PC-CREAM were generally in good agreement with the measured data, and the results from different models were also generally consistent with each other. However, the COMPLY predictions were generally lower than those from PC-CREAM. This is of concern, as the aim of a screening model (COMPLY) is to provide conservative estimates of contaminant concentrations. Further investigation of this problem is required. The general implications of the results for further model development are discussed. (author)

[en] Information about residential radon levels in low and middle income countries is very sparse. In response to the World Health Organization initiative in the International Radon Project, we propose a research project that will address this knowledge gap in South America by conducting a residential radon survey. Following initial in vitro and in vivo studies of radon and studies of uranium miners exposed to radon, over twenty large case-control studies of lung cancer risk from exposure to residential radon have been completed worldwide by year 2004. Recently pooled data from these individual studies have been analyzed. These collaborative analyses of the indoor studies in Europe, North America, and China provide strong direct evidence that radon is causing a substantial number of lung cancers in the general population. To reduce radon lung cancer risk, national authorities must have methods and tools based on solid scientific evidence to develop sound public health policies. We propose to conduct a survey in ten South American countries using the distribution and analysis of passive alpha tracking detectors in houses selected at random in pre-selected cities in each participating country. We also present an approach to estimate the cost of carrying out such a survey and the radon laboratory infrastructure needed. The results of the proposed survey will allow to conduct assessment of the exposure to residential radon in the populations of South American countries and to assess the health impact of this exposure. The results of the project will also help national health authorities in developing national residential radon action levels and regulations, as well as provide public health guidance for radon awareness and mitigation. (author)

[en] Naturally occurring radionuclides in building materials are one of the sources of radiation exposure of the population. This study was undertaken with the purpose of determining radioactivity in some Cuban building materials and for assessing the annual effective dose to Cuban population due external gamma exposure in dwellings for typical Cuban room model. Forty four samples of raw materials and building products were collected in some Cuban provinces. The activity concentrations of natural radionuclides were determined by gamma ray spectrometry using a p-type coaxial high purity germanium detector and their mean values are in the ranges: 9 to 857 Bq.kg^-1 for ⁴⁰K; 6 to 57 Bq.kg^-1 for ²²⁶Ra; and 1.2 to 22 Bq.kg^-1 for ²³²Th. The radium equivalent activity in the 44 samples varied from 4 Bq.kg^-1 (wood) to 272 Bq.kg^-1 (brick). A high pressure ionisation chamber was used for measuring of the indoor absorbed dose rate in 543 dwellings and workplaces in five Cuban provinces. The average absorbed dose rates in air ranged from 43 nGy.h-1 (Holguin) to 73 nGy.h-1 (Camagueey) and the corresponding population-weighted annual effective dose due to terrestrial gamma radiation was estimated to be 145 ± 40 μSv. This dose value is 16% higher than the calculated value for typical room geometry of Cuban house. (author)

[en] Tritium in the UK environment causes low radiation doses to the public, but uncertainty exists in the dose coefficient for the organically-bound component of tritium (OBT). This can affect the assessment of effective doses to representative persons. Contributing to that uncertainty is poor knowledge of the body retention time of OBT and how this varies for different OBT compounds in food. This study was undertaken to measure the retention time of tritium by volunteers after eating sole from Cardiff Bay, which may contain OBT from discharges from the GE Healthcare Ltd. plant. Five volunteers provided samples of excreta over periods up to 150 days after intake. Preliminary analysis of the results suggests retention of total tritium with body half-times ranging from 4 to 11 days, with no evidence of a significant contribution due to retention with a longer half-time. This range covers the half-time of 10 days used by the ICRP for tritiated water. The short timescale could be due to rapid hydrolysis in body tissues of the particular form of OBT used in this study. Implications for the dose coefficient for OBT are that the use of the ICRP value of 4.2 10^-11 Sv Bq^-1 may be cautious in this specific situation, and the value of 1.6 10^-11 Sv Bq^-1 used by the ICRP for tritiated water might even be more appropriate. These observations on dose coefficients are separate from any implications of recent discussion on whether the tritium radiation weighting factor should be increased from 1 to 2. (author)