Portable Gamma Spectrometry Surveys of Sites in Portugal in Support of the VADOSE Project

The VADOSE project involves the use of multiple techniques to evaluate dose rate variability on different spatial scales. Several sites in central northern Portugal, mostly in the vicinity of Aveiro, have been investigated. As part of this investigation, portable gamma spectrometry techniques were used to map areas of approximately 100x100m around each sampling location. The SUERC portable gamma spectrometry system used consists of a 3x3” NaI(Tl) spectrometer with integral GPS receiver. Measurements were conducted with 10s integration time. Maps of the dose rate variability in each area were generated in the field, and used to confirm data quality and coverage and identify any remaining locations that would benefit from further measurements prior to leaving the site. Maps of natural radionuclide distribution (40K, 214Bi from the 238U decay series, and 208Tl from the 232Th decay series) were produced after the conclusion of measurements each day. Natural radionuclide specific activities (Bq kg-1 ) were estimated using a spectral windows method with stripping1 , using a working calibration assuming planar geometry and uniform activity distribution. As agreed prior to the start of work, a working calibration derived from field measurements and photon fluence calculations conducted for similar detectors in the 1990s2 has been used here, with calibration parameters given in the appendix. This report presents the dose rate maps produced during the field work, with a very brief description of the data. Summary statistics for each data set are presented in Table 1. All data have been mapped using a UTM (zone 29T) grid, with the approximate location of ground features added by hand as a guide. Further work could be conducted to produce more accurate overlays of ground features. At each site in-situ gamma spectrometry measurements were also conducted by ITN, and the data collected by the two detector systems and the soil samples will be compared at a later date

Mobile gamma Spectrometry Measurements of Coneyside Beach, Cumbria

<p>Environmental radioactivity arises from natural and anthropogenic sources: 238U, 232Th and their decay products, and 40K in differing concentrations in rocks and soils; natural materials transformed by industrial processes to enhance the concentrations of some radioactive isotopes; materials discharged from some nuclear processes; fallout from nuclear accidents and weapons testing; radioactive sources that may have been lost or stolen; and radiation shine from sites using nuclear technology. Mobile gamma spectrometry provides powerful methods of measuring the distribution of radioactivity in the environment; airborne platforms allow the rapid survey of large areas, and ground based platforms more detailed surveys of smaller areas.</p> <p>Airborne surveys in 1990 (conducted to produce a baseline data set for the Sellafield site) and 2000 (as part of a large study on spatial and temporal aspects of airborne measurements) showed several radiometric features along the coast, including elevated 137Cs activity along a beach in West Cumbria between St Bees and Nethertown, in an environment comprising pebbles and gravel where this was unexpected. An additional short survey of this area was conducted during the 2000 survey, at reduced ground clearance and speed, to verify the existence of these unexpected signals. With increased interest in the search and recovery of particulate activity from the beaches in the vicinity of Sellafield, this data was reviewed in 2008 to illustrate the use of airborne methods in locating potential particulate activity on beaches and to aid in the planning of further ground based investigations. SUERC conducted an exploratory ground based survey in June 2010; to investigate whether the features observed in the airborne surveys were still present, to define the spatial distribution of activity more precisely, and to attempt to assess the form of the activity and whether it had been redistributed since 2000. This report presents the 2000 airborne measurements reviewed in 2008, with the results of the June 2010 survey.</p> <p>A portable gamma spectrometry system has been developed at SUERC. This consists of a 3x3” NaI(Tl) detector with digital spectrometer, a GPS receiver and netbook computer. The system is lightweight, easy to use and can be carried over terrain that would be inaccessible to vehicular systems. By holding the detector close to the ground the extent of any observed enhanced activity feature can be determined more precisely. Two of these systems have been field tested on the 22-23rd June 2010 along this beach.</p> <p>The exploratory survey has clearly demonstrated the utility of the SUERC backpack system in producing detailed maps of the distribution of radioactive materials in the environment. A survey using two systems successfully mapped an area of approximately 50x200m with very high density measurements in a period of approximately 2h.</p> <p>It has shown that the enhanced 137Cs activity is still present on the beach, in locations that are consistent with the earlier airborne measurements. The more detailed survey shows a pattern of patches of enhanced 137Cs activity. Samples collected from some of these had concentrations of 50 Bq kg-1, which would account for the observed 137Cs count rate. The nature of the material that carries this activity is at present unknown.</p&gt

Effect of muscle force during stretch on eccentric contraction-induced muscle damage

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recor

The effect of flight line spacing on radioactivity inventory and spatial feature characteristics of airborne gamma-ray spectrometry data

Airborne Gamma Spectrometry (AGS) is well suited to the mapping of radioactivity in the environment. Flight parameters (e.g. speed and line spacing) directly affect the rate of area coverage, cost, and data quality of any survey. The influences of line spacing have been investigated for data from inter‐tidal, coastal and upland environments with a range of <sup>137</sup>Cs activity concentrations and depositional histories. Estimates of the integrated <sup>137</sup>Cs activity (‘inventory’) within specified areas and the shapes of depositional features were calculated for subsets of the data at different line spacings. Features with dimensions greater than the line spacing show variations in inventory and area of less than 3%, and features with dimensions less than the line spacing show larger variations and a decreased probability of detection. The choice of line spacing for a task is dependent on the dimensions of the features of interest and required edge definition. Options for line spacing for different tasks are suggested. It is noted that for regional mapping, even 5–10 km line spacing can produce useful data

Scale model behaviour and float geometry influence on an oscillating water column system

A numerical model based on a 1:60 scale Lazy-S Mooring Line has been developed using the dynamic analysis software OrcaFlex, to determine the software’s capabilities when analysing discretized scale models, and to quantify the effect that varying float surface geometry has on mooring line system damping. Static analysis was performed, followed by dynamic analysis, based on experimental data from physical testing in the University of Plymouth 35m Sediment Flume tank, against two distinct float shapes with equivalent hydrostatic properties but aspect ratio variance perpendicular to fluid flow. The impact of scale modelling on static line forces, effective tension and driving frequency were evaluated as a comparative base between the experimental and numerical findings, and the intricacies of scale modelling evaluated in the context of the OrcaFlex software. Evaluation of Static Line Forces (SLF) finds that systems comprised of taut lines at scale can misinterpret line tension as constant and may not exhibit expected static and dynamic tension behaviour, theorized as due to the nodal method OrcaFlex adopts for calculating line tension. Dynamic analysis of driving frequency amplitude suggests an agreement of behaviour between data sets – i.e, a reduced surface area results in a greater driving frequency of tension loading, particularly in the Heave direction of Oscillating Water Column (OWC) motion – based on the original defined float types and a proposed plate of 30% greater drag area. Drag area was determined to have a reduced influence at higher frequencies due to motion lag within the system such that, as OWC motion scales past a certain threshold, optimisation of float geometry will yield diminishing returns. Consequently, evaluation of results suggests that numerical scale modelling in OrcaFlex is an appropriate method for modelling behaviour as a function of changing hydrostatic properties, but that consideration must be made when modelling taut scale systems to limit potential numerical discrepancies

On the extraction of disjunctive landmarks from planning problems via symmetry reduction

The exploitation of symmetry in combinatorial search has typically focused on using information about symmetries to control search. This work describes an approach that exploits symmetry to get more detailed domain-analysis rather than as a method of search control

Mechanical and energetic determinants of optimal cycling cadence

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recor

Safety, the Preface Paradox and Possible Worlds Semantics

This paper contains an argument to the effect that possible worlds semantics renders semantic knowledge impossible, no matter what ontological interpretation is given to possible worlds. The essential contention made is that possible worlds semantic knowledge is unsafe and this is shown by a parallel with the preface paradox

Fertility control as a means of controlling bovine tuberculosis in badger (Meles meles) populations in south-west England: predictions from a spatial stochastic simulation model

A spatial stochastic simulation model was used to assess the potential of fertility control, based on a yet-to-be-developed oral bait-delivered contraceptive directed at females, for the control of bovine tuberculosis in badger populations in south-west England. The contraceptive had a lifelong effect so that females rendered sterile in any particular year remained so for the rest of their lives. The efficacy of fertility control alone repeated annually for varying periods of time was compared with a single culling operation and integrated control involving an initial single cull followed by annually repeated fertility control. With fertility control alone, in no instance was the disease eradicated completely while a viable badger population (mean group size of at least one individual) was still maintained. Near eradication of the disease (less than 1% prevalence) combined with the survival of a minimum viable badger population was only achieved under a very limited set of conditions, either with high efficiency of control (95%) over a short time period (1-3 years) or a low efficiency of control (20%) over an intermediate time period (10-20 years). Under these conditions, it took more than 20 years for the disease to decline to such low levels. A single cull of 80% efficiency succeeded in near eradication of the disease (below 1% prevalence) after a period of 6-8 years, while still maintaining a viable badger population. Integrated strategies reduced disease prevalence more rapidly and to lower levels than culling alone, although the mean badger group size following the onset of control was smaller. Under certain integrated strategies, principally where a high initial cull (80%) was followed by fertility control over a short (1-3 year) time period, the disease could be completely eradicated while a viable badger population was maintained. However, even under the most favourable conditions of integrated control, it took on average more than 12 years following the onset of control for the disease to disappear completely from the badger population. These results show that whilst fertility control would not be a successful strategy for the control of bovine tuberculosis in badgers if used alone, it could be effective if used with culling as part of an integrated strategy. This type of integrated strategy is likely to be more effective in terms of disease eradication than a strategy employing culling alone. However, the high cost of developing a suitable fertility control agent, combined with the welfare and conservation implications, are significant factors which should be taken into account when considering its possible use as a means of controlling bovine tuberculosis in badger populations in the UK