12 results on '"J. R. Simmonds"'
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2. An overview of nickel mineralisation in Africa with emphasis on the Mesoproterozoic East African Nickel Belt (EANB)
- Author
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David M. Evans, J. P. P. M. Hunt, and J. R. Simmonds
- Subjects
Peridotite ,geography ,geography.geographical_feature_category ,010504 meteorology & atmospheric sciences ,Geochemistry ,Great Dyke ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,Mineral resource classification ,Igneous rock ,Layered intrusion ,Mining engineering ,Sill ,Magma ,Laterite ,engineering ,General Earth and Planetary Sciences ,Geology ,0105 earth and related environmental sciences - Abstract
Nickel production in Africa takes place principally in Botswana, South Africa and Zimbabwe, with much of the South African and Zimbabwean production being a by-product of platinum-group element mining in the Bushveld Complex and Great Dyke. Several large nickel deposits have been discovered elsewhere in Africa but until recently, their development has been hindered by political risk and limitations in energy and transport infrastructure. Most of the continent is significantly underexplored with respect to base metals, including the area covered by the East African Nickel Belt (EANB). The known nickel deposits of the EANB all occur in mafic-ultramafic intrusive rocks of the Mesoproterozoicage Kibaran igneous event. These intrusive bodies take the form of medium to large layered intrusions, small dynamic magma conduits (chonoliths and sills) and dyke swarms. Laterite deposits are developed over exposed dunite and peridotite lithologies in the basal sequence of larger layered intrusions, whereas nickel sulphide deposits are developed at the base of the small chonoliths. Geochronological and geochemical data suggests that all intrusions in the EANB formed in a single magmatic event (1350 to 1400 Ma) and were derived from a picritic parental magma, which was variably contaminated in mid to upper-crustal staging chambers by metasedimentary rocks. As a result, nickel sulphide mineralisation was formed in all of the intrusions, but in most, the grades and tenors are too low to be considered economic in the foreseeable future. In the 1970s, government-led regional surveys identified a large nickel laterite deposit at Musongati in Burundi and a nickel sulphide deposit at Kabanga in the northwest of Tanzania. These deposits have subsequently been explored and delineated by mining companies, but they remain undeveloped due to their distance to the coast and a lack of transport and energy infrastructure. The Kabanga sulphide deposit now comprises a total mineral resource of 58 million tonnes grading 2.6% nickel. The Musongati laterite deposit comprises an overall resource of 122 million tonnes with a grade of 1.4% nickel.
- Published
- 2016
- Full Text
- View/download PDF
3. Use of effective dose
- Author
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Hans-Georg Menzel, Colin J. Martin, P. Ortiz López, Richard Wakeford, John Harrison, J. R. Simmonds, Mikhail Balonov, and Rebecca Smith-Bindman
- Subjects
medicine.medical_specialty ,Population ,Radiation Dosage ,Risk Assessment ,Effective dose (radiation) ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,Radiation Protection ,0302 clinical medicine ,medicine ,Relative biological effectiveness ,Humans ,Radiology, Nuclear Medicine and imaging ,Medical physics ,Total effective dose equivalent ,education ,education.field_of_study ,Radiological and Ultrasound Technology ,business.industry ,Equivalent dose ,Public Health, Environmental and Occupational Health ,Reproducibility of Results ,Radiation Exposure ,Collective dose ,030220 oncology & carcinogenesis ,Absorbed dose ,Risk assessment ,Nuclear medicine ,business ,Relative Biological Effectiveness - Abstract
International Commission on Radiological Protection (ICRP) Publication 103 provided a detailed explanation of the purpose and use of effective dose and equivalent dose to individual organs and tissues. Effective dose has proven to be a valuable and robust quantity for use in the implementation of protection principles. However, questions have arisen regarding practical applications, and a Task Group has been set up to consider issues of concern. This paper focusses on two key proposals developed by the Task Group that are under consideration by ICRP: (1) confusion will be avoided if equivalent dose is no longer used as a protection quantity, but regarded as an intermediate step in the calculation of effective dose. It would be more appropriate for limits for the avoidance of deterministic effects to the hands and feet, lens of the eye, and skin, to be set in terms of the quantity, absorbed dose (Gy) rather than equivalent dose (Sv). (2) Effective dose is in widespread use in medical practice as a measure of risk, thereby going beyond its intended purpose. While doses incurred at low levels of exposure may be measured or assessed with reasonable reliability, health effects have not been demonstrated reliably at such levels but are inferred. However, bearing in mind the uncertainties associated with risk projection to low doses or low dose rates, it may be considered reasonable to use effective dose as a rough indicator of possible risk, with the additional consideration of variation in risk with age, sex and population group.
- Published
- 2016
- Full Text
- View/download PDF
4. An assessment of the present and future implications of radioactive contamination of west Cumbria
- Author
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J R Simmonds, A Mayall, and T Cabianca
- Subjects
Radionuclide ,Dose limit ,Waste management ,Impact assessment ,Radiological weapon ,Radioactive contamination ,Public Health, Environmental and Occupational Health ,Environmental science ,General Medicine ,Waste Management and Disposal - Abstract
The Sellafield nuclear fuels reprocessing plant operated by BNFL on the Cumbrian coast in the UK has been discharging radionuclides to the marine and atmospheric environments since the early 1950s. In recent years the site has been the subject of a series of radiological impact assessments carried out by the NRPB. The paper summarises and presents the results of one particular study: an assessment of the average individual doses in west Cumbria over the next two centuries from past and projected future discharges from the site. In all cases doses were below the dose limit for the general public.
- Published
- 1996
- Full Text
- View/download PDF
5. Food consumption rates for use in generalised radiological dose assessments
- Author
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J Byrom, J R Simmonds, B Walters, R R Taylor, and C Robinson
- Subjects
Estimation ,business.industry ,digestive, oral, and skin physiology ,Public Health, Environmental and Occupational Health ,Food consumption ,General Medicine ,Work (electrical) ,Agriculture ,Environmental health ,Radiological weapon ,Medicine ,Survey data collection ,Christian ministry ,business ,Waste Management and Disposal - Abstract
In 1990, the Ministry of Agriculture, Fisheries and Food (MAFF) Working Party on Radionuclides in Food agreed that a standard set of UK food consumption data was needed for the estimation of radiation doses from ingestion. It was decided that MAFF and the National Radiological Protection Board (NRPB) as two of the main users of such figures would work together to produce a set of revised food consumption data. Tn the past MAFF and NRPB have used food consumption data which have differed slightly in detail. The aim of the work described is to provide an agreed set of data for general use in the two organisations and elsewhere, for example by local authorities and nuclear operators. The availability of survey data on dietary habits, collected within the past 12 years, for adults, schoolchildren and infants offered the opportunity for revising the previous estimates of food consumption and producing a new and comprehensive set of data.
- Published
- 1995
- Full Text
- View/download PDF
6. Patient need at the heart of workforce planning: the use of supply and demand analysis in a large teaching hospital's acute medical unit
- Author
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L Poole, M J R Simmonds, and I R Le Jeune
- Subjects
Medical unit ,business.industry ,Process (engineering) ,Professional Issues ,media_common.quotation_subject ,Personnel Staffing and Scheduling ,General Medicine ,State Medicine ,United Kingdom ,Supply and demand ,Teaching hospital ,Patient need ,Resource (project management) ,Nursing ,Medical Staff, Hospital ,Medicine ,Workforce planning ,Humans ,Operations management ,Quality (business) ,business ,Hospitals, Teaching ,Hospital Units ,Needs Assessment ,media_common - Abstract
Timely medical assessment is integral to the safety and quality of healthcare delivery in acute medicine. Medical staff are an expensive resource. This study aimed to develop a modelling system that facilitated efficient workforce planning according to patient need on the acute medical unit. A realistic 24-hour ‘supply’ of junior doctors was calculated by adjusting the theoretical numbers on the rota for leave allowances, natural breaks and other ward duties by a combination of direct observation of working practice and junior doctor interviews. ‘Demand’ was analysed using detailed admission data. Supply and demand were then integrated with data from a survey of the time spent on the process of clerking and assessment of medical admissions. A robust modelling system that predicted the number of unclerked patients was developed. The utility of the model was assessed by demonstrating the impact of a regulation-compliant redesign of the rota using existing staff and by predicting the most efficient use of an additional shift. This simple modelling system has the potential to enhance quality of care and efficiency by linking workforce planning to patient need.
- Published
- 2012
7. Review of trends in the UK population dose
- Author
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J R Simmonds, W B Oatway, A L Jones, and J S Hughes
- Subjects
Adult ,medicine.medical_specialty ,Population ,Health protection ,Radiation Dosage ,Effective dose (radiation) ,Radiation Protection ,Environmental health ,Occupational Exposure ,medicine ,Dosimetry ,Humans ,Medical physics ,education ,Radiometry ,Waste Management and Disposal ,education.field_of_study ,business.industry ,Public Health, Environmental and Occupational Health ,General Medicine ,Environmental exposure ,Environmental Exposure ,Collective dose ,United Kingdom ,Radiological weapon ,Radiation protection ,business - Abstract
The Radiation Protection Division of the Health Protection Agency (HPA-RPD), formerly the National Radiological Protection Board, has periodically reported the doses to members of the public and workers in the UK from all sources of radiation. This paper is a review of the doses reported in these publications from the 1970s to 2000 or later. The paper aims to present how the estimated doses received by the UK population have changed over this time period, and where possible from earlier years as well, from all sources of radiation. It was not possible to directly compare the doses reported in the earlier reports. There have been changes in the type of doses estimated, the dosimetry (in particular the definition of effective dose) and improvements made in the measurement of natural background doses. In these cases the earlier reported doses have been recalculated using modern dosimetry so that the doses can be compared. The occupational doses reported in this paper are for those workers involved in the civil nuclear power production industry, industrial radiography or from the medical use of radiation sources. For workers it was found that the individual and collective dose has decreased significantly over this time through the introduction of legislation, the improvement in technology and better working practices. Members of the public are exposed to radiation following the atmospheric testing of nuclear weapons, discharges from UK civil nuclear sites and from diagnostic radiology as well as from natural sources. Exposure to anthropogenic sources has decreased over the period considered in this paper. However, the dose to the UK population as a whole, presented as a per caput dose to a population of 55 million, has not changed significantly as it is dominated by the constant level of exposure to natural sources of radiation.
- Published
- 2008
8. Consultative exercise on dose assessments
- Author
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D Sumner, B A Bridges, T Parker, and J R Simmonds
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Medical education ,Operations research ,business.industry ,media_common.quotation_subject ,Memorandum ,Food standards ,Public Health, Environmental and Occupational Health ,General Medicine ,Environmental Exposure ,Radiation Dosage ,Method development ,United Kingdom ,Presentation ,Agency (sociology) ,Medicine ,Humans ,Steering group ,business ,Radiometry ,Waste Management and Disposal ,Food Contamination, Radioactive ,media_common ,Power Plants - Abstract
A summary is given of a meeting held at Sussex University, UK, in October 2000, which allowed the exchange of ideas on methods of assessment of dose to the public arising from potential authorised radioactive discharges from nuclear sites in the UK. Representatives of groups with an interest in dose assessments were invited, and hence the meeting was called the Consultative Exercise on Dose Assessments (CEDA). Although initiated and funded by the Food Standards Agency, its organisation, and the writing of the report, were overseen by an independent Chairman and Steering Group. The report contains recommendations for improvement in co-ordination between different agencies involved in assessments, on method development and on the presentation of data on assessments. These have been prepared by the Steering Group, and will be taken forward by the Food Standards Agency and other agencies in the UK. The recommendations are included in this memorandum.
- Published
- 2001
9. Updates to UK emergency and recovery advice following changes in international guidance
- Author
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J. R. Simmonds, K. Mortimer, Anne Nisbet, and Stephanie Haywood
- Subjects
Scope (project management) ,Operations research ,Renewable Energy, Sustainability and the Environment ,business.industry ,Process (engineering) ,Health, Toxicology and Mutagenesis ,Public Health, Environmental and Occupational Health ,Public consultation ,Safety standards ,Phase (combat) ,Transport accidents ,Nuclear Energy and Engineering ,Medicine ,Operations management ,Duration (project management) ,Safety, Risk, Reliability and Quality ,business ,Waste Management and Disposal ,Advice (complexity) - Abstract
HPA is updating and consolidating its advice on radiation emergencies and recovery. Current advice was published in 1997. Since 2007, the ICRP has issued a set of recommendations to elaborate its guidance for emergency exposure and existing exposure situations. It is expected that the European Basic Safety Standards, when published, will also reflect the ICRP recommendations. The new ICRP guidance represents a marked change in approach, with emphasis placed on optimisation of whole protection strategies using reference levels of residual dose. These new concepts as well as the relevant lessons identified following the Fukushima accident will be included in the new UK advice document. The scope of the UK advice includes reactor and transport accidents as well as releases from waste stores, reprocessing and defence activities. The revised advice will consider the initiation of emergency countermeasures based on averted dose criteria and optimisation of the subsequent protection strategy based on reference levels of residual dose. The advice will illustrate that the type of protection strategy selected depends on the contribution of different exposure pathways over time to projected dose, and this will vary according to the scenarios considered as reasonably foreseeable. Due to the potential impact of the advice, a wide range of stakeholders are being consulted. In particular, feedback will be required on the potential for adapting current practices for sheltering and stable iodine prophylaxis to situations involving longer duration releases or those with a prolonged threat phase. The advice document will contain guidance for emergency planning and response, criteria for the withdrawal of emergency countermeasures, factors to consider during the transition to an existing exposure situation and the management of long term contaminated areas. It is the first time that the whole spectrum of advice will be presented in a single publication, which is expected to be published in 2013, following a public consultation process.
- Published
- 2013
- Full Text
- View/download PDF
10. Review of trends in the UK population dose.
- Author
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A L Jones, W B Oatway, J S Hughes, and J R Simmonds
- Subjects
RADIATION dosimetry ,RADIOLOGY ,RADIATION ,GREAT Britain. National Radiological Protection Board - Abstract
The Radiation Protection Division of the Health Protection Agency (HPA-RPD), formerly the National Radiological Protection Board, has periodically reported the doses to members of the public and workers in the UK from all sources of radiation. This paper is a review of the doses reported in these publications from the 1970s to 2000 or later. The paper aims to present how the estimated doses received by the UK population have changed over this time period, and where possible from earlier years as well, from all sources of radiation. It was not possible to directly compare the doses reported in the earlier reports. There have been changes in the type of doses estimated, the dosimetry (in particular the definition of effective dose) and improvements made in the measurement of natural background doses. In these cases the earlier reported doses have been recalculated using modern dosimetry so that the doses can be compared. The occupational doses reported in this paper are for those workers involved in the civil nuclear power production industry, industrial radiography or from the medical use of radiation sources. For workers it was found that the individual and collective dose has decreased significantly over this time through the introduction of legislation, the improvement in technology and better working practices. Members of the public are exposed to radiation following the atmospheric testing of nuclear weapons, discharges from UK civil nuclear sites and from diagnostic radiology as well as from natural sources. Exposure to anthropogenic sources has decreased over the period considered in this paper. However, the dose to the UK population as a whole, presented as a per caput dose to a population of 55 million, has not changed significantly as it is dominated by the constant level of exposure to natural sources of radiation. [ABSTRACT FROM AUTHOR]
- Published
- 2007
- Full Text
- View/download PDF
11. Parameters for Modelling the Interception and Retention of Deposits from Atmosphere by Grain and Leafy Vegetables
- Author
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G. S. Linsley and J. R. Simmonds
- Subjects
Air Pollutants ,Epidemiology ,Health, Toxicology and Mutagenesis ,Vegetation ,Models, Theoretical ,Contamination ,Plutonium ,Atmosphere ,Deposition (aerosol physics) ,Unit mass ,Agronomy ,Air Pollutants, Radioactive ,Cesium Radioisotopes ,Environmental chemistry ,Vegetables ,Strontium Radioisotopes ,Environmental science ,Radiology, Nuclear Medicine and imaging ,Leafy vegetables ,Interception ,Edible Grain - Abstract
The Normalised Specific Activity (NSA), a quantity which relates the concentration of a contaminant per unit mass of vegetation to its daily rate of ground deposition, has been used as the basis for determining interception factors and retention half-lives for radioactive contaminants deposited on grain and leafy vegetables. The values are for use in assessing contamination levels on crops at harvest during conditions of continuous deposition. The approach implicitly takes account of other processes which influence foliar contamination, namely, translocation and dilution due to plant growth. The respective NSA values for grain and prepared leafy vegetables determined from several separate experimental studies are fairly constant and are of about the same level for fall-out strontium and caesium. There is evidence from previous studies on herbage to suggest that similar NSA values might be expected for other contaminants on grain and leafy vegetables. Plutonium is an exception in that NSA values for grain and prepared leafy vegetables are lower than those for the fission products by factors of between 5 and 10 depending upon the source of the contaminant. Consideration has been given to determining the most appropriate value of the fraction of activity transferred from grain to flour during refining. This is an element dependent parameter and the values estimated for strontium, caesium and plutonium are respectively 0.15, 0.5 and 0.1. The study has indicated the need for data in several areas in order to improve the capability to model interception and retention on field crops in continuous and acute release conditions.
- Published
- 1982
- Full Text
- View/download PDF
12. Normalized specific activities for Pu deposition onto foliage
- Author
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J E, Pinder, K W, McLeod, J R, Simmonds, and G S, Linsley
- Subjects
Plants, Toxic ,Air Pollutants, Radioactive ,Tobacco ,Vegetables ,Edible Grain ,Food Contamination, Radioactive ,Plutonium ,Environmental Monitoring - Published
- 1985
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