A practical approach to limit the radiation dose from building materials applied in dwellings, in compliance with the Euratom Basic Safety Standards.

Individuals receive a significant part of their radiation exposure indoors. We anticipate that this exposure is likely to increase in the near future, due to a growing use in the building industry of recycled materials and materials previously regarded as waste. Such materials often contain elevated levels of natural radionuclides. Directive 2013/59/Euratom ('Basic Safety Standards', BSS) pays comprehensive attention to indoor exposure from natural radionuclides, but proper implementation of all corresponding BSS regulations is not straightforward, especially when regarding the regulation of building materials containing so-called Annex XIII materials. In this paper, we discuss the most relevant deficiencies in the BSS and present a practical approach to cope with these. Our most important observation is that adequate methods for assessing the annual dose due to gamma radiation from building materials are not provided by the BSS. This is in particular difficult because compliance of single building materials has to be tested, but the corresponding BSS reference level refers to gamma radiation emitted by all building materials present in a room. Based on a simple model of three layers of building materials, we present a set of operational conditions for building materials, either used for construction purposes ('bulk layers') or for the finishing of walls, floors and ceilings ('superficial layers'). Any customary combination of building materials meeting these conditions will stay below the BSS reference level for gamma radiation. This statement holds for the middle of a reference room, but is not always the case close to the walls, especially when low density materials with a relatively high content of natural radionuclides are present at the inner side of the room. This can be avoided by applying more strict conditions for those kind of materials than presented in this paper. We further focus on the indoor exposure to thoron progeny. Building materials that pass the test for gamma radiation can still be a significant source for indoor air concentrations of thoron progeny. When the average annual thoron inhalation dose were to be restricted to 1 mSv a-1 - a level comparable to the BSS reference level for gamma radiation - the activity concentration of Ra-224 in (especially porous) building materials used for wall finishing purposes should be limited to a value of typically 50 Bq kg-1. Even if our suggested approach of the BSS regulations is fully implemented, it still allows for a significant increase in the average radiation exposure in dwellings due to external radiation and thoron progeny. However, the situation will be worse if a less strict interpretation of the BSS regulations will be applied.

An assessment of the effectiveness of UK building regulations for new homes in Radon Affected Areas.

Radon, a naturally occurring radioactive gas generated underground by radioactive decay of nuclides contained in certain types of rocks, can concentrate inside buildings, where it poses the second-largest risk factor for lung cancer, after smoking. The highest concentrations of domestic radon in the UK occur in the south-western counties of Devon and Cornwall, but certain areas in Northamptonshire and surrounding counties in the English Midlands also have high levels. It has been shown that it is possible both to reduce the radon concentrations in existing houses and to build new homes with appropriate protection. Since 1999, the UK's Building Regulations have specified that all new homes should be built with a combined radon-proof/damp-proof membrane plus, in Radon Affected Areas, a sump under the building. However, the building regulations do not require that the radon level is measured once the house is built and so there is little information on the effectiveness of these measures. Builders generally do not mention radon, and when asked, just confirm that their houses are built to current standards. To better understand the efficacy or otherwise of the currently mandated radon-protection measures, a cross-sectional investigation was carried out in 26 new housing developments in high-radon areas in Northamptonshire. In a targeted mail-shot, 1056 householders were invited to apply for a free radon test; 124 replied (11.7%). In total, 94 pairs of detectors were returned (70.1% of responders), of which two were spoiled, giving a total of 92 results. Following processing and seasonal correction, the arithmetic mean radon concentration in the target houses was 45% of the arithmetic mean radon concentration in existing houses in the postcode sectors where the houses were built and were approximately log-normally distributed. No results exceeded the UK Action Level of 200 Bq. m-3 but three were above the Target Level of 100 Bq. m-3. The results suggest that the radon-proof membranes in general ensure that radon concentrations in new homes constructed in accordance with the Building Regulations in Radon Affected Areas (RAAs) are satisfactorily low. However, there is a very small statistical probability that levels in a small number of homes will be close to or above the Action Level, particularly in areas of high radon potential. As a result, the Public Health England (PHE) recommendation for testing in the first year of occupation should be adopted as a legal requirement.

The 2014 Integrated Field Exercise of the Comprehensive Nuclear-Test-Ban Treaty revisited: The case for data fusion.

The International Monitoring System of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) uses a global network of radionuclide monitoring stations to detect evidence of a nuclear explosion. The two radionuclide technologies employed-particulate and noble gas (radioxenon) detection-have applications for data fusion to improve detection of a nuclear explosion. Using the hypothetical 0.5 kT nuclear explosive test scenario of the CTBTO 2014 Integrated Field Exercise, the intrinsic relationship between particulate and noble gas signatures has been examined. This study shows that, depending upon the time of the radioxenon release, the particulate progeny can produce the more detectable signature. Thus, as both particulate and noble gas signatures are inherently coupled, the authors recommend that the sample categorization schemes should be linked.

Ingredients for a Dutch radon action plan, based on a national survey in more than 2500 dwellings.

A new Euratom directive demands that Member States establish a national action plan for indoor radon. Important requirements are a national reference level for the radon concentration in dwellings, actions to identify dwellings with radon concentrations that might exceed this reference level and the encouragement of appropriate measures to reduce the radon concentrations in dwellings where these are high. This paper provides ingredients and recommendations for a national action plan for radon in dwellings, applicable to the Netherlands. The approach presented here, which may serve as a model for other countries or regions with a comparatively favourable indoor radon situation, is based on the analysis of radon data from a national survey in more than 2500 Dutch dwellings, built since 1930. The annual average activity concentration of radon in dwellings in the Netherlands equals 15.6 ± 0.3 Bq m-3. The 50th and 95th percentiles were found to be 12.2 and 38.0 Bq m-3, respectively. In 0.4 per cent of the dwellings we found values above 100 Bq m-3. Radon concentrations showed correlations with type of dwelling, year of construction, ventilation system, soil type and smoking behaviour of inhabitants. The survey data suggest that it is feasible for the Netherlands to adopt a national reference level for radon in dwellings of 100 Bq m-3, in line with recommendations by WHO and ICRP. We were able to predict dwellings with a moderate probability for radon concentrations above 100 Bq m-3 by applying a combination of three selection criteria: location, type of dwelling and manner of ventilation. Of the existing 6.2 million dwellings in the Netherlands (built since 1930), approximately 23-24 thousand are suspected to exceed this level. Some 80% of these are found in the group of naturally ventilated single-family dwellings in either the southern part of Limburg (approx. 13 thousand) or the Meuse-Rhine-Waal river delta (approx. six thousand). This selected group of dwellings represents 7% of the housing stock. In contrast to many other countries in Europe and elsewhere, radon concentrations in dwellings above 200 Bq m-3 are very rare in the Netherlands. As a result, relatively simple and inexpensive measures in existing Dutch single-family dwellings will be sufficient to reduce indoor radon concentrations above the proposed national reference level of 100 Bq m-3 to values well below.

A comparison of dose results from the Clean Air Act Assessment Package-1988, personal computer (CAP88-PC), version 3 to previous versions.

Computer software packages approved by the U.S. Environmental Protection Agency (U.S. EPA), including CAP88-PC, are used by U.S. Department of Energy (U.S. DOE) sites to demonstrate compliance with the radionuclide air emission standard under the Clean Air Act. CAP88-PC version 3, was approved by the U.S. EPA in February 2006 for use by U.S. DOE facilities. Version 3 incorporates several major changes that have the potential to affect calculated doses relative to calculations using earlier versions. This analysis examined the types and magnitudes of changes to dose estimates for specific radionuclides calculated using the version 3 software compared with the previous versions. For parent radionuclides and for the total dose from radionuclide chains, total effective dose calculated with version 3 was compared to effective dose equivalent calculated with previous versions. Various comparisons were also performed to determine which of the updates in version 3 accounted for changes in overall dose estimates. CAP88-PC version 3 would produce substantially different results relative to previous versions of the code for a number of radionuclides, including some isotopes that may be present at U.S. DOE facilities, as well as those used for industrial and medical applications. In general, doses for many radionuclides were lower using version 3 but doses for a few key radionuclides increased relative to the previous versions.

British atomic tests in Australia.

The United Kingdom and Australia have reached agreement on the British payment for cleaning up the Maralinga (South Australia) site at which the UK tested some of its atomic weapons in the 1960s. The tests were conducted amid great secrecy and only in recent years has the truth about the health hazards fully emerged. The peace movement opposed the tests and its stand has been vindicated. Also vindicated have been the claims by Aborigines that more damage was done by the tests than was earlier admitted.

Regulatory control of indoor Rn.

Regulation of indoor Rn is explored in the context of cost-effectiveness of regulatory action. Evaluation of cost (i.e., mitigation expenses) and benefits (i.e., savings associated with medical expenses and lost productivity related to lung cancer) at various action levels indicate that regulatory programs would be economically inefficient and unreasonable if standards were established at or below the current EPA action guide (150 Bq m-3 or less). For the approximately 95% of U.S. homes with Rn levels near or below 150 Bq m-3, government programs should continue to focus on public information and consumer protection. For the small number of homes with high Rn levels, government programs should focus on identifying high risk homes and encouraging homeowners to reduce Rn levels. Because of the potential for substantial risk reduction, such efforts would be cost-effective in these homes.