Abstract: The aetiology of childhood leukaemia remains generally unknown, although exposure to moderate and high levels of ionising radiation, such as was experienced during the atomic bombings of Japan or from radiotherapy, is an established cause. Risk models based primarily upon studies of the Japanese A-bomb survivors imply that low-level exposure to ionising radiation, including to ubiquitous natural background radiation, also raises the risk of childhood leukaemia. In a recent paper (Wakeford et al 2009 Leukaemia 23 770–6) we estimated the proportion of childhood leukaemia incidence in Great Britain attributable to natural background radiation to be about 20%. In this paper we employ the two sets of published leukaemia risk models used previously, but use recently published revised estimates of natural background radiation doses received by the red bone marrow of British children to update the previous results. Using the newer dosimetry we calculate that the best estimate of the proportion of cases of childhood leukaemia in Great Britain predicted to be attributable to this source of exposure is 15–20%, although the uncertainty associated with certain stages in the calculation (e.g. the nature of the transfer of risk between populations and the pertinent dose received from naturally occurring alpha-particle-emitting radionuclides) is significant. The slightly lower attributable proportions compared with those previously derived by Wakeford et al (Leukaemia 2009 23 770–6) are largely due to the lower doses (and in particular lower high LET doses) for the first year of life.

Abstract: Sudden increases in the background gamma-radiation dose may occur due to the removal of 222Rn and 220Rn progeny from the atmosphere by wet deposition mechanisms. This contribution has been measured using a Geiger–Muller detector at the Atomic Weapons Establishment (Aldermaston, UK) during July 2005–April 2006. The results are approximated by a log-normal distribution and there were nine separate occurrences of the gamma-radiation dose exceeding 125% of the geometric mean value. The increases were associated with periods of heavy rainfall, although no correlation was evident between the dose rate and the amount of rainfall, as increased rainfall dilutes the activity further rather than increasing its atmospheric removal. The events were preceded by periods of fine weather and atmospheric stability that allow for the build-up of 222Rn and 220Rn progeny. Similar increases in gamma-radiation dose have been measured at a nearby monitoring station situated approximately 11 miles from Aldermaston. Increases in gamma-radiation dose during heavy rainfall have also been observed throughout the UK, that followed the trajectory of an air mass. All events decreased to typical values within 1–2 h as the water permeated into the ground below and the radioactivity decayed away.

Abstract: In order to optimise the monitoring of potentially exposed workers, it is desirable to determine specific values of absorption for the compounds handled. This study derives specific values of absorption rates for different chemical forms of plutonium from in vitro and animal (monkeys, dogs, mice, rats) experiments, and from human contamination cases. Different published experimental data have been reinterpreted here to derive values for the absorption parameters, fr, sr and ss, used in the human respiratory tract model currently adopted by the International Commission on Radiological Protection (ICRP). The consequences of the use of these values were investigated by calculating related committed effective doses per unit intake. Average and median estimates were calculated for fr, sr ,a ndss for each plutonium compound, that can be used as default values for specific chemical forms instead of the current reference types. Nevertheless, it was shown that the use of the current ICRP reference absorption types provides reasonable approximations. Moreover, this work provides estimates of the variability in pulmonary absorption and, therefore, facilitates analyses of the uncertainties associated with assessments, either from bioassay measurements or from prospective calculations, of intake and dose.

Abstract: Using fuzzy set theory, this paper presents results from risk analyses that explore potential exposure of medical operators working in a high dose rate brachytherapy irradiation plant. In these analyses, the HEART methodology, a first generation method for human reliability analysis, has been employed to evaluate the probability of human error. This technique has been modified on the basis of fuzzy set concepts to take into account, more directly, the uncertainties of the so-called error-promoting factors on which the method is based. Moreover, with regard to some identified accident scenarios, fuzzy potential dose was also evaluated to estimate the relevant risk. The results also provide some recommendations for procedures and safety equipment to reduce the occurrence of radiological exposure accidents.

Abstract: Testicular cancer is a rare disease, affecting mainly young men aged 15-49. There have been some recent reports that it might be associated with radiation exposure. We have systematically reviewed this topic. English-language articles published between 1990 and 2008 studying the relationship between occupational radiation exposure and testicular cancer were included. Risk of bias was assessed using a modified version of the EPHPP checklist. For ionising radiation we subdivided study populations into occupational groups. No pooled analysis was performed due to the heterogeneity of studies. Seven case-control and 30 cohort studies were included in the review. For radiation workers, one incidence study showed a significant increase and four showed no effect. Eight mortality studies did not indicate an effect while four showed a non-significant increase. Incidence among persons with military exposure was not increased in two studies and non-significantly increased in another two. Among aircrew studies, one showed no effect against five with slight increases. Medical exposure studies showed no increases. For EMF exposure, three studies showed no effect, two reported a significant and four a non-significant increase in incidence. Overall, there was very limited evidence for associations between occupational ionising radiation and testicular cancer, while there were some positive associations for EMF. Testicular cancer mortality is generally low and was not associated with radiation. New incidence studies are recommended to investigate the association between radiation exposure and testicular cancer where exposure is better specified and individually estimated.

Abstract: 5-androstenediol (5-AED) has been advanced as a possible countermeasure for treating the haematological component of acute radiation syndrome (ARS). It has been used in animal models to stimulate both innate and adaptive immunity and treat infection and radiation-induced immune suppression. We here report on the safety, tolerability and haematologic activity of 5-AED in four double-blinded, randomized, placebo-controlled studies on healthy adults including elderly subjects. A 5-AED injectable suspension formulation (NEUMUNE) or placebo was administered intramuscularly as either a single injection, or once daily for five consecutive days at doses of 50, 100, 200 or 400 mg. Subjects (n = 129) were randomized to receive NEUMUNE (n = 95) or the placebo (n = 34). NEUMUNE was generally well-tolerated; the most frequent adverse events were local injection site reactions (n = 104, 81%) that were transient, dose-volume dependent, mild to moderate in severity, and that resolved over the course of the study. Blood chemistries revealed a transient increase (up to 28%) in creatine phosphokinase and C-reactive protein levels consistent with intramuscular injection and injection site irritation. The blood concentration profile of 5-AED is consistent with a depot formulation that increases in disproportionate increments following each dose. NEUMUNE significantly increased circulating neutrophils (p < 0.001) and platelets (p < 0.001) in the peripheral blood of adult and elderly subjects. A dose–response relationship was identified. Findings suggest that parenteral administration of 5-AED in aqueous suspension may be a safe and effective means to stimulate innate immunity and alleviate neutropenia and thrombocytopenia associated with ARS.

Abstract: In some areas of Estonia, groundwater contains a significant number of natural radionuclides, especially radium isotopes, which may cause radiation protection concern depending on the geological structure of the aquifer. Indeed, the parametric value of 0.1 mSv y⁻¹ for the total indicative dose established by European Directive 98/83/EC, adopted as a limit value in Estonian national legislation, is often exceeded. A Twinning Project between Estonia and Italy was carried out within the framework of the Estonian Transition Facility Programme, sponsored by the European Union. Its aims were to assess the radiological situation of Estonian groundwater and related health consequences. The first step was a study of Estonian aqueducts and the population served by them, and a thorough analysis of the radiological database for drinking water, from which the relevant effective doses for the population were obtained. Particular attention was devoted to doses to children and infants. Correlations between the chemical parameters were investigated, in order to suggest the best possible analytical approach. Lastly, a monitoring strategy, i.e. sampling points and sampling frequencies, was proposed.

Abstract: A study of peak skin doses (PSDs) during neuroradiology and cardiology interventional procedures has been carried out using Gafchromic XR-RV2 film. Use of mosaics made from squares held in cling film has allowed doses to the head to be mapped successfully. The displayed cumulative air kerma (CAK) has been calibrated in terms of cumulative entrance surface dose (CESD) and results indicate that this can provide a reliable indicator of the PSD in neuroradiology. Results linking PSD to CESD for interventional cardiology were variable, but CAK is still considered to provide the best option for use as an indicator of potential radiation-induced effects. A CESD exceeding 3?Gy is considered a suitable action level for triggering follow-up of patients in neuroradiology and cardiology for possible skin effects. Application of dose action levels defined in this way would affect 8% of neurological embolisation procedures and 5% of cardiology ablation and multiple stent procedures at the hospitals where the investigations were carried out. A close relationship was observed between CESD and dose?area product (DAP) for particular types of procedure, and DAPs of 200?300? Gy?cm2 could be used as trigger levels where CAK readings were not available. The DAP value would depend on the mean field size and would need to be determined for each application.

Abstract: Radon is a radioactive gas which makes the primary contribution to the natural radiation to which people are exposed. For that reason, great importance is attributed to the determination of radon concentration levels in water, indoor air and soil gas and outdoors. In this paper, measurements of radon concentration in soil gas have been carried out around some areas of the Upper Siwaliks of the Kala Amb, Nahan and Morni Hills, India, using a portable AlphaGUARD PQ 2000 device into which the soil gas is drawn using active pumping. The soil gas radon concentration around the Upper Siwaliks was found to vary from 11.5 ± 0.9 to 78.47 ± 3.1 kBq m − 3. The annual average indoor radon concentration in the study area was measured in the range from 71.7 ± 21.0 to 421.7 ± 33.6 Bq m − 3 using LR-115 type II cellulose nitrate films in the bare mode. The values of soil gas radon concentration in the study area were compared with those from the adjoining low-radioactive areas of Punjab. Since the soil or bedrock beneath a building is one of the sources of radon gas in the indoor air, an effort has been made to find a possible correlation between soil gas radon with the indoor radon. A satisfactory positive correlation has been observed between soil gas radon and indoor radon in the study area.

Abstract: The relationship between patient cross-sectional area and both volume CT dose index (CTDI) and dose length product was explored for abdominal CT in vivo, using a 16 multidetector row CT (MDCT) scanner with automatic exposure control. During a year-long retrospective survey of patients with MDCT for symptoms of abdominal sepsis, cross-sectional areas were estimated using customised ellipses at the level of the middle of vertebra L3. The relationship between cross-sectional area and the exposure parameters was explored. Scans were performed using a LightSpeed 16 (GE Healthcare Medical Systems, Milwaukee, WI) operated with tube current modulation. From a survey of 94 patients it was found that the CTDI increased with the increase in patient cross-sectional area. The relationship was logarithmic rather than linear, with a least-squares fit to the data (R(2) = 0.80). For abdominal CT the cross-sectional area gave a measure of patient size based on the region of the body to be exposed. Exposure parameters increased with increasing cross-sectional area and the greater radiation exposure of larger patients was partly a consequence of their size. Given increasing obesity levels we believe that cross-sectional area and scan length should be added to future dose surveys, allowing patient size to be considered as a factor of relevance when examining population doses.

Abstract: A number of models are being used to assess the potential environmental impact of releases of radioactivity. These often use a tiered assessment structure whose first tier is designed to be highly conservative and simple to use. An aim of using this initial tier is to identify sites of negligible concern and to remove them from further consideration with a high degree of confidence. In this paper we compare the screening assessment outputs of three freely available models. The outputs of these models varied considerably in terms of estimated risk quotient (RQ) and the radionuclide-organism combinations identified as being the most limiting. A number of factors are identified as contributing to this variability: values of transfer parameters (concentration ratios and K(d)) used; organisms considered; different input options and how these are utilised in the assessment; assumptions as regards secular equilibrium; geometries and exposure scenarios. This large variation in RQ values between models means that the level of confidence required by users is not achieved. We recommend that the factors contributing to the variation in screening assessments be subjected to further investigation so that they can be more fully understood and assessors (and those reviewing assessment outputs) can better justify and evaluate the results obtained.

Abstract: Interventional cardiology (IC) procedures are known to give high radiation doses to patients and cardiologists as they involve long fluoroscopy times and several cine runs. Patients' dose measurements were carried out at the cardiology department in a local hospital in Penang, Malaysia, using Gafchromic XR-RV2 films. The dosimetric properties of the Gafchromic film were first characterised. The film was energy and dose rate independent but dose dependent for the clinically used values. The film had reproducibility within ? 3% when irradiated on three different days and hence the same XR-RV2 dose?response calibration curve can be used to obtain patient entrance skin dose on different days. The increase in the response of the film post-irradiation was less than 4% over a period of 35 days. For patient dose measurements, the films were placed on the table underneath the patient for an under-couch tube position. This study included a total of 44 patients. Values of 35?2442?mGy for peak skin dose (PSD) and 10.9?344.4?Gy?cm2 for dose?area product (DAP) were obtained. DAP was found to be a poor indicator of PSD for PTCA procedures but there was a better correlation (R2 = 0.7344) for CA + PTCA procedures. The highest PSD value in this study exceeded the threshold dose value of 2?Gy for early transient skin injury recommended by the Food and Drug Administration.

Abstract: This study was carried out to assess the annual per capita effective dose from medical diagnostic procedures using computed tomography (CT) in Canada Relevant data concerning the nature and the frequency of various diagnostic CT examinations were obtained from the reports on Medical Imaging in Canada and Diagnostic Services in Ontario Doses associated with examinations of different types were based primarily on typical effective doses used in the National Council on Radiation Protection and Measurements Report 160 with considerations of limited dose information surveyed in Canada The results show that the per capita annual effective dose from diagnostic CT exams was 074 mSv in 2006, up from 019 mSv in 1991 This significant increase in population radiation dose from CT scans is due mainly to a more than doubling in the examination rate and to a higher radiation dose per procedure from the newer generation of multi-detector CTs

Abstract: The problem of finding a simple, generally applicable description of worldwide measured ambient dose equivalent rates at aviation altitudes between 8 and 12 km is difficult to solve due to the large variety of functional forms and parametrisations that are possible. We present an approach that uses Bayesian statistics and Monte Carlo methods to fit mathematical models to a large set of data and to compare the different models. About 2500 data points measured in the periods 1997-1999 and 2003-2006 were used. Since the data cover wide ranges of barometric altitude, vertical cut-off rigidity and phases in the solar cycle 23, we developed functions which depend on these three variables. Whereas the dependence on the vertical cut-off rigidity is described by an exponential, the dependences on barometric altitude and solar activity may be approximated by linear functions in the ranges under consideration. Therefore, a simple Taylor expansion was used to define different models and to investigate the relevance of the different expansion coefficients. With the method presented here, it is possible to obtain probability distributions for each expansion coefficient and thus to extract reliable uncertainties even for the dose rate evaluated. The resulting function agrees well with new measurements made at fixed geographic positions and during long haul flights covering a wide range of latitudes.

Abstract: Concentrations of tritium in sea water and marine biota as reported over the last approximately 10 years from monitoring programmes carried out by this laboratory under contract to the UK Food Standards Agency are reviewed from three areas: near Cardiff; Sellafield; and Hartlepool. Near Cardiff, enhancement of concentration factors (CFs) above an a priori value of approximately 1 have already been studied, and attributed to compounds containing organically bound tritium in local radioactive waste discharges. Further data for Cardiff up to 2006 are reported in this note. Up to 2001, CFs increased to values of more than approximately 7000 in flounders and approximately 4000 in mussels, but have subsequently reduced; this variability could be due to changes in the organic constitution of compounds discharged. Near Sellafield and Hartlepool, enhancements to the tritium concentration factor are observed but they are relatively small compared with those near Cardiff. Near Sellafield, plaice and mussels appear to have a CF for tritium of approximately 10; in some cases concentrations of tritium in winkles are below detection limits and positively measured values indicate a CF of approximately 3. The variation could be due to mechanisms of uptake by the different organisms. Near Hartlepool there were only a few cases where tritium was positively measured. These data give a value of approximately 5 for the CF in plaice (on the basis of two samples); approximately 15 in winkles (eight samples); and > 45 in mussels (two samples). Any differences between the behaviours at Sellafield and Hartlepool would need to be confirmed by improved measurements. Possible causes are the organic composition of the effluent and differences in environmental behaviour and uptake by organisms near the two sites. These potential causes need further investigation. It is emphasised that results from tritium analyses are heavily method dependent; thus comparison with results from other programmes needs to take this into account. Further, the results for enhancement of CF will also depend on the definition of CF itself.

Abstract: Tritium ( 3 H) is a radioactive isotope of hydrogen that is ubiquitous in environmental and biological systems. Following debate on the human health risk from exposure to tritium, there have been claims that the current biokinetic model recommended by the International Commission on Radiological Protection (ICRP) may underestimate tritium doses. A new generic model for tritium in mammals, based on energy metabolism and body composition, together with all its input data, has been described in a recent paper and successfully tested for farm and laboratory mammals. That model considers only dietary intake of tritium and was extended to humans. This paper presents the latest development of the human model with explicit consideration of brain energy metabolism. Model testing with human experimental data on organically bound tritium (OBT) in urine after tritiated water (HTO) or OBT intakes is presented. Predicted absorbed doses show a moderate increase for OBT intakes compared with doses recommended by the ICRP. Infants have higher tritium retention—a factor of 2 longer than the ICRP estimate. The highest tritium concentration is in adipose tissue, which has a very low radiobiological sensitivity. The ranges of uncertainty in retention and doses are investigated. The advantage of the new model is its ability to be applied to the interpretation of bioassay data.

Abstract: The paper presents the development of a model for the calculation of the gamma radiation dose rate from a cloud or plume of radionuclides. The model has been implemented in the Lagrangian puff dispersion model DIPCOT which is used in the framework of the RODOS system for nuclear emergency management. The basic characteristics of the model are its speed of execution and its ability to calculate the gamma dose rates from clouds or plumes of random shape formed under non-homogeneous meteorological conditions or over complicated topography. The three-dimensional integral that would normally have to be numerically calculated in such circumstances has been transformed to a one-dimensional one through a coordinate transformation for each model puff and by using a separation of variables technique. The resulting one-dimensional integrals have been pre-calculated and their values stored for a range of parameters that cover the possible ranges of photon energies, puff dimensions and distances encountered in cases of atmospheric dispersion. During runtime the model calculates the exact values by interpolation from stored tables of values. This is a very fast and accurate method, as the evaluation study has proved. The model performance has been evaluated through simulations of a real-scale experiment involving routine emissions of (41)Ar from a reactor and comparisons of model predictions with measured fluence rates. The comparisons have revealed a satisfactory level of agreement and the model performance statistical indices are well above the acceptance criteria that are suggested in the literature.

Abstract: This paper studies the mortality and cancer morbidity of the 470 male workers involved in tackling the 1957 Sellafield Windscale fire or its subsequent clean-up. Workers were followed up for 50 years to 2007, extending the follow-up of a previously published cohort study on the Windscale fire by 10 years. The size of the study population is small, but the cohort is of interest because of the involvement of the workers in the accident. Significant excesses of deaths from diseases of the circulatory system (standardised mortality ratio (SMR) = 120, 95% CI = 103–138; 194 deaths) driven by ischaemic heart disease (IHD) (SMR = 133, 95% CI = 112–157, 141 deaths) were found when compared with the population of England and Wales but not when compared with the population of Northwest England (SMR = 105, 95% CI = 90–120 and SMR = 115, 95% CI = 97–136 respectively). When compared with those workers in post at the time of the fire but not directly involved in the fire the mortality rate from IHD among those involved in tackling the fire was raised but not statistically significantly (rate ratio (RR) = 1.11, 95% CI = 0.92–1.33). A RR of 1.11 is consistent with an excess relative risk of 0.65 Sv − 1 as reported in an earlier study of non-cancer mortality in the British Nuclear Fuels plc cohort of which these workers are a small but significant part. There was a statistically significant difference in lung cancer mortality (RR = 2.18, 95% CI = 1.05–4.52) rates between workers who had received higher recorded external doses during the fire and those who had received lower external doses. Comparison of the mortality rates of workers directly involved in the accident with workers in post, but not so involved, showed no significant differences overall. On the basis of the use of a propensity score the average effect of involvement in the Windscale fire on all causes of death was − 2.13% (se = 3.64%, p = 0.56) though this difference is not statistically significant. The average effect of involvement in the Windscale fire was − 5.53% (se = 3.81, p = 0.15) for all cancers mortality and 6.60% (se = 4.03%, p = 0.10) for IHD mortality though neither figure was statistically significant. This analysis of the mortality and cancer morbidity experience of those Sellafield workers involved in the 1957 Windscale fire does not reveal any measurable effect of the fire upon their health. Although this study has low statistical power for detecting small adverse effects, due to the relatively small number of workers, it does provide reassurance that no significant health effects are associated with the 1957 Windscale fire even after 50 years of follow-up.

Abstract: Workplace exposure to coherent and incoherent optical radiation from artificial sources is regulated under the Artificial Optical Radiation Directive (AORD) 2006/25/EC, now implemented in the UK under the Control of Artificial Optical Radiation at Work Regulations (AOR) 2010. These regulations set out exposure limit values. Implementing the AOR (2010 Health and Safety Statutory Instrument No 1140 www.legislation.gov.uk/uksi/2010/1140/pdf/uksi_20101140_en.pdf) requirements in a hospital environment is a potentially complex problem because of the wide variety of sources used for illumination, diagnosis and therapy. A survey of sources of incoherent optical radiation in a large hospital is reported here. The survey covers examples of office lighting, operating theatre lighting, examination lamps, and sources for ultraviolet phototherapy and visible phototherapies, including photodynamic therapy and neonatal blue-light therapy. The results of the survey are used to inform consideration of the strategy that a hospital might reasonably adopt both to demonstrate compliance with the AOR (2010) and to direct implementation effort.

Abstract: This paper provides an overview of key issues associated with the application of currently available biota dose assessment methods to consideration of potential environmental impacts from geological disposal facilities. It explores philosophical, methodological and practical assessment issues and reviews the implications of test assessment results in the context of recent and on-going challenges and debates.

Abstract: Previously we reported that elevated circulating concentrations of the acute-phase (AP) protein ?2-macroglobulin (?2M), either as typically occurring in pregnant female rats or after administration to male rats, provides radioprotection, displayed as 100% survival of experimental animals exposed to total-body irradiation with 6.7?Gy (LD50/30) x-rays, that is as effective as that afforded by the synthetic radioprotector amifostine. The finding that amifostine administration induces a 45-fold increase in ?2M in the circulation led us to hypothesise that ?2M assumes an essential role in both natural and amifostine-mediated radioprotection in the rat. In the present work we examined the activation of cytoprotective mechanisms in rat hepatocytes after the exogenous administration of ?2M and amifostine. Our results showed that the IL6/JAK/STAT3 hepatoprotective signal pathway, described in a variety of liver-injury models, upregulated the ?2M gene in amifostine-pretreated animals. In both ?2M-?and amifostine-pretreated rats we observed the activation of the Akt signalling pathways that mediate cellular survival. At the cellular level this was reflected as a significant reduction of irradiation-induced DNA damage that allowed for the rapid and complete restoration of liver mass and ultimately at the level of the whole organism the complete restoration of body weight. We conclude that the selective upregulation of ?2M plays a central role in amifostine-provided radioprotection.

Abstract: In the very early stages of response to an accidental release of radioactivity leading to environmental contamination, it is likely that only limited measurements of radioactivity in the local environment will be available on which to base decisions concerning protection measures and radiation monitoring activities. Model predictions will be used to aid understanding of the radiological situation and to form a basis for emergency health protection decisions. This paper presents an analysis of the relative importance of contributors to the imprecision associated with emergency response calculations based on a few off-site measurements, using predictions from the UK Met Office's NAME III (Numerical Atmospheric dispersion Modelling Environment version 5.2) dispersion model. The results presented extend those from a previous study in which a simple Gaussian plume model was used and confirm the key parameters contributing to imprecision. The potential extent of the sheltering countermeasure resulting from a hypothetical release in real weather conditions occurring in 2007 and 2008 is also presented.

Abstract: Etched track detectors are widely used for the detection of radon and its decay products. The reliability of radon measurement performed with such devices requires that laboratories producing analytical data are able to provide results of the required quality. The need for uniform results from laboratories at an international level therefore requires the implementation of a quality assurance programme, the harmonization of criteria, sampling procedures, calculations and the reporting of results, agreed on the basis of fundamental principles and international standards. The quality assurance programme described here is the first step on the way to ISO/IEC 17025 certification for the RI-RN (ISPESL) laboratory.

Abstract: This paper presents an approach to estimating and displaying the imprecision associated with predictions from early emergency response calculations based on a limited number of off-site measurements and incomplete information about the nature of the release. The method enables key elements of imprecision to be included in the assessment in a simple and transparent manner, notably those arising from alternative weather evolutions, release durations, and factors influencing the amount of radioactivity deposited to ground. The presentation of assessment results incorporating lack of knowledge in a way that is easily understandable is important in the context of emergency decision making, and options for alternative styles of display are presented and discussed. A new system of early emergency response for radiological releases to atmosphere based on this approach is under development.

Abstract: Between 2004 and 2009, the Surplus Source Disposal Programme (SSDP) arranged and subsidised the safe disposal or recycling of more than 11 000 unwanted radioactive items containing in total more than 8.5 × 1014 Bq of activity, from some 500 sites throughout the United Kingdom. Sources were removed principally from universities, schools and colleges, museums, and hospitals. SSDP was funded by the UK Government and managed by the Environment Agency. The programme was delivered at a total cost of £7.14 million, nearly £2 million less than its initial budget. This was a big success for health and safety, the environment, business and the public purse. Current legislative requirements under the High Activity Sealed Sources Directive, which came into effect during 2005, will prevent a build-up of high activity surplus sources in future. Continuing vigilance may be needed to avoid a build-up of lower activity disused sources.

Abstract: A number of vocational training courses are held in caves in the Yorkshire Dales region of the United Kingdom. The instructors and students involved in these courses have the potential to be exposed to enhanced levels of radon (222Rn) and its progeny as a result of their occupations. A prior radiological risk assessment for the training courses recommended that an environmental monitoring programme be carried out to establish the radon concentrations in the caves, and that the caving instructors wear personal radon dosemeters. Radon gas concentrations varied seasonally, being at their highest in summer and their lowest in winter. The lowest result was 40 Bq m−3 recorded in Lower Longchurn cave during winter, whilst the highest result was 4440 Bq m−3 recorded in Crackpot cave during the summer. As the individuals involved in the caving are entering atmospheres with radon gas concentrations in excess of 400 Bq m−3, the Ionising Radiation Regulations 1999 (GB Parliament 2000 Ionising Radiations Regulations 1999 (London: Stationary Office) SI 1999/3232) apply. A system of work is therefore in place to control exposure to radon. This system of work stipulates an initial dose investigation level of 1 mSv, a second dose investigation level of 2 mSv and an annual dose limit of 6 mSv. The highest annual dose recorded to date is 2.2 mSv, although the average (median) annual dose is only 0.5 mSv.

Abstract: To measure the unattached fraction of radon progeny, a new type of portable, low cost, reusable integrating monitor with etched track detector (CR-39) was developed. This monitor simultaneously gives the average equilibrium-equivalent concentrations of unattached (222)Rn progeny (EEC(Rn)(u)), attached (222)Rn progeny (EEC(Rn)(a)) and also (220)Rn progeny (EEC(Tn)). It was calculated, according to the detection efficiencies which were derived by the Monte Carlo method, that the lower detection limits for EEC(Rn)(u), EEC(Rn)(a) and EEC(Tn) are 0.03 Bq m(-3), 0.12 Bq m(-3) and 0.07 Bq m(-3), respectively for 24 h integrating sampling at a flow rate of 2.92 l min(-1). The validity of the new monitor was confirmed through a series of intercomparison experiments.