Radiological Implications Research Articles

LUDEP 1.0, A Personal Computer Program to Implement the New ICRP Respiratory Tract Model

The International Commission on Radiological Protection has recently approved a new model of the human respiratory tract. This model has been designed to represent realistically the deposition and biokinetic behaviour of inhaled radionuclides, and to calculate doses to the respiratory tract. In order to examine the practical application and radiological implications of the new model, a Personal Computer program has been developed. LUDEP 1.0 (LUung Dose Evaluation Program) is a user-friendly program for the IBM-compatible PC which enables the user to calculate doses to the respiratory tract and to other organs

LUDEP 1.0, A Personal Computer Program to Implement the New ICRP Respiratory Tract Model

The International Commission on Radiological Protection has recently approved a new model of the human respiratory tract. This model has been designed to represent realistically the deposition and biokinetic behaviour of inhaled radionuclides and to calculate doses to the respiratory tract. In order to examine the practical application and radiological implications of the new model, a Personal Computer program has been developed. LUDEP 1.0 (LUng Dose Evaluation Program) is a user-friendly program for the IBM-compatible PC which enables the user to calculate doses to the respiratory tract and to other organs.

The natural radioactivity of the rock phosphates, phosphatic products and their environmental implications

The radioactivity of the Minjingu phosphorite deposit in Arusha-Tanzania was determined by radiochemical and radiometric methods of analysis. The main radioisotopes analysed in the rock phosphate, phosphate concentrate (ground rock phosphate), phosphate fertilizers (superphosphate, and triple superphosphate) and phosphogypsum were 238U, 235U, 232Th and their progenies.Uranium-238 and its progenies had high activity concentrations of ≈4000 Bq kg−1 in all materials analysed, whereas phosphogypsum had high 226Ra, in contrast to triple superphosphate fertilizer.Extensive use of ground rock phosphate, and phosphate fertilizers was assessed in relation to their radiological implications to the farmers. The external radiation arising from the use of phosphate fertilizers in agricultural fields was found to be less than 2% of normal background radiation (50 nGy h−1).A model for pathways of the natural radionuclides from the ground rock phosphate, phosphate fertilizers and by-products is proposed in order to assess their long-term impacts on the secondary environment.

The behaviour of plutonium and americium in the shoreline waters of the Irish Sea: A review of Harwell studies in the 1990s

In order to make reliable predictions of future doses arising from the plutonium and americium discharged into the Irish Sea from BNFL Sellafield, a thorough understanding of the behaviour of these actinides in the adjacent shoreline waters is necessary. The studies which have been undertaken in order to achieve this understanding are reviewed in the present paper. Descriptions are given of the methods of sample collection, experimental field measurements and their interpretation, including the use of computer-based dynamic models. These indicate the variations in actinide concentrations as a function of time and of distance from Sellafield. The radiological implications are also mentioned. Some areas for possible future research are briefly outlined.

Distribution of radionuclides in mussels, winkles and prawns. Part 1. Study of organisms under environmental conditions using conventional radio-analytical techniques

Mussels ( Mytilus edulis) and winkles ( Littorina littorea), collected from Ravenglass, Cumbria, England in the vicinity of the British Nuclear Fuels plc nuclear reprocessing plant at Sellafield, and prawns ( Palaemon serratus), landed nearby at Whitehaven, have been investigated to determine the distributions of α-emitting ( 210Po, 238Pu, 239 + 240Pu, 241Am) and γ-emitting ( 95Nb, 95Zr, 103Ru, 106Ru, 137Cs, 241Am) radionuclides in their tissues and organs. Ravenglass mussels exhibited 239 + 240Pu concentrations ranging from 43 Bq kg −1 dry in muscle tissue to 1658 Bq kg −1 dry in byssal threads, the corresponding 137Cs range being 131–1340 Bq kg −1. Although 210Po concentrations were not determined in byssal threads, muscle tissue still displayed the lowest polonium concentration (124 Bq kg −1), whilst the viscera (containing digestive gland, stomach and kidneys) contained the highest (596 Bq kg −1). Subsequent concentration factor estimates for 137Cs, 210Po and 239 + 240Pu in the total soft parts of Ravenglass mussels were, respectively, 9, 25 800 and 1400. In Cumbrian winkles, nuclide concentrations ranged for 239 + 240Pu, from 18·5 Bq kg −1 dry (muscle tissue) to 457 Bq kg −1 dry (pallial complex); for 137Cs, from 103 (foot tissue) to 1495 Bq kg −1 (pallial complex) and for 210Po, from 12·2 (muscle tissue) to 145 Bq kg −1 (digestive gland). Total soft part concentration factors (CFs) were calculated to be 16 for 137Cs, 5500 for 210Po and 5700 for 239 + 240Pu. The magnitude of these CFs, as for those in the mussel, is consistent with the respective CF values recommended by the International Atomic Energy Agency for molluscs. Radionuclide concentrations in Whitehaven-landed prawns were much lower than those observed in mussels or winkles; no artificial γ-emitter activities were present above detection limits and the highest 239 + 240Pu concentration was 5·96 Bq kg −1 dry in the carapace. 210Po activities, however, were more readily detectable throughout the prawn's tissues, concentrations ranging from 2·7 Bq kg −1 (abdomen muscle) to 144 Bq kg −1 (cardiac foregut), producing CFs of the order of 2 × 10 4 in tissues associated with feeding and digestion. Previous studies have attempted to determine the principal nuclide source to marine organisms by comparing nuclide activity ratios in their tissues, sea water and particulate material. From the environmental samples studied here, no single transport medium appears to dominate uptake. The primary radiological implication of the observed radionuclide concentrations in Ravenglass mussels and winkles is that, from seafood ingestion, the critical group receives only a small percentage (ca. 10%) of the ICRP-recommended subsidiary dose limit. Dose contributions from 210Po are higher than those from 239 + 240Pu in mussels but are less than those from 239 + 240Pu in winkles.

Radiological implications of inhaled 239Pu and 241Am in dusts at the former nuclear test site in Maralinga.

The biokinetics of 239Pu and 241Am present in three dust samples obtained from Maralinga were investigated after their deposition in the rat lung. Results were used as an experimental basis for assessing the radiological implications for human exposure. The transfer rates of these actinides to blood in the various dusts differed by 50-fold. The most transportable forms were compatible with a material that had 25% class W and 75% class Y characteristics. The doses per unit intake for adults, children, and infants exposed to an aerosol of 5 microns AMAD were calculated to be, respectively, 0.059, 0.076, and 0.140 mSv Bq-1. The corresponding doses for the least transportable forms were the same as those calculated for a class Y compound, namely 0.036, 0.049, and 0.096 mSv Bq-1. The behavior of the actinides in humans was predicted by combining the transfer rates to blood with mechanical clearance data obtained after volunteers had inhaled 85Sr or 88Y labeled fused aluminosilicate particles. The results suggested that monitoring of 241Am in the chest could be used to advantage for assessing intakes incurred by workers involved with any further decontamination procedures but would be of little practical value for assessing inadvertent public exposure. The paper includes comments on the relevance of the 1990 ICRP recommendations and the proposed new dosimetric model for the respiratory tract.

Neutron activation of elements and the radiological implications for development and use of low activation materials

At this stage it is impossible to specify the requirements on low activation materials in a comprehensive way. Instead, simplified criteria are proposed as a general means of establishing the compositional guidelines for selecting and designing these materials. An approach to criteria development is described, comprising: • - comprehensive identification of potentially relevant types of radiological impact: • - identification of the important radionuclides for each element for each type of impact: • - assessment of the radiological impacts associated with the use of unit amount of each element. Overall consequences can then be scaled according to design information and radiologically-based requirements on materials can be inferred. Conclusions are presented from a study following this approach, identifying objectives and specifications for materials with respect to each area of radiological impact.

Renal arteries: anatomic study for surgical and radiological practice.

The renal arterial supply was analyzed in 266 kidneys dissected from 133 fixed adults subjects. The anatomical findings are presented: 1 hilar artery in 53.3% of the cases, 1 hilar artery with 1 superior pole extra-hilar branch in 14.3%, 2 hilar arteries in 7.9%, 3 hilar arteries in 1.9%, superior polar artery in 6.8%, inferior polar artery in 5.3% and other variations in 8.5%. The urological and radiological implications of these findings in kidney transplantation, renovascular hypertension, renal trauma, interventional radiology, conservative surgery and oncologic surgery are discussed.

LUDEP: A Lung Dose Evaluation Program

A Task Group of the ICRP is currently reviewing its dosimetric model for the respiratory tract with the aim of producing a more comprehensive and realistic model which can be used both for dosimetry and bioassay purposes. This in turn requires deposition, clearance, and dosimetry to be treated in a more detailed manner in than in the current model. In order to examine the practical application and radiological implications of the proposed model, a microcomputer program has been developed in a modular form so that changes can be easily included as the model develops. LUDEP (Lung Dose Evaluation Program) is a user-friendly menu-driven program which can be operated on any IBM-compatible PC. It enables the user to calculate (a) doses to each region of the respiratory tract and all other body organs, and (b) excretion rates and retention curves for bioassay purposes. 11 refs., 4 figs., 6 tabs.

Duplication of the Vertebro‐Basilar System

During the examination of 75 fixed brains and 2086 vertebral angiograms we encountered two cases of fenestration of the vertebral artery and two cases of partial duplication of the basilar artery. In the first case, an 81 year old male, there was fenestration, of the basilar artery at the union of the two vertebral arteries. The fenestration was 9mm long with no associated vascular disease. The other partial duplication of the basilar artery was observed in the upper portion of the artery in a 54 year old male patient investigated angiographically for subarachnoid haemorrhage. The fenestration of the third case was demonstrated in the intracranial part of the right vertebral artery of a 50 year old female patient during digital subtraction angiography for subarachnoid haemorrhage. In the fourth case, the fenestration was found angiographically at the atlanto-axial level in the extracranial portion of the left vertebral artery in a 37 year old female patient with subarachnoid haemorrhage from an arteriovenous malformation in the left cerebral hemisphere. The embryonic, histological and radiological implications of the duplication are discussed.

Personal perspectives on radioactivity in the environment

This article is in essence a compilation of personal views on future research priorities in the environmental radioactivity and related fields. It is intended to exhibit the same spirit of frankness and openness of expression which has characterised Eric Hamilton's science and his dissemination of it. The review works its way round some of the research priorities which currently underpin the author's research programme at SURRC (Scottish Universities Research and Reactor Centre). In particular, further research on occupational and environmental exposures to natural decay series radionuclides is called for. More generally, the wider radiological implications of inhalation of low activity dusts merit detailed study. Aerial radiometrics and mass-spectrometry-based analytical methods are highlighted as areas for expansion. The former is considered to show unsurpassed potential in emergency response situations and in detailed and cost-effective mapping of both natural (U, Th, total γ) and anthropogenic nuclides (e.g. in the study of on-land movement of the Sellafield-contaminated mud-patch or the characterisation of Chernobyl fallout depositions). The latter methods will ultimately enable more definitive study of low concentrations of long-lived nuclides3in key components of target human tissues and in geochemical/geophysical extracts of important environmental samples. The need for revision of legislation and practices associated with occupational exposures at, and discharges to the environment from, conventional industries which involve ores, minerals, etc. containing natural radioactivity is further emphasised herein, including the suggestion that fossil fuel and nuclear power generation industries should be subject to more equivalent requirements and expectations. Some possible consequences of recent research on the association between radiation and childhood leukaemia are suggested. Sub-natural modification of the radiation environment is likely to become a common practice. This article is dedicated to Eric Hamilton, a scientist who has in the U.K., an unsurpassed record of achievement in the environmental radioactivity and biogeochemical fields.

Military Sabotage of Nuclear Facilities: The Implications

In June 1981, a squadron of Israeli military aircraft descended out of a setting sun to drop sixteen 2000-pound bombs on an Iraqi research reactor under construction in the vicinity of Baghdad. The successful attack created a worldwide media sensation. Congressional hearings were held within weeks to establish the motivations and lessons. Attention focused on proliferation. Jerusalem rationalized its action on the grounds that Iraq intended to use the facility to acquire the feedstock for a nuclear weapons program. The potential radiological implications of an attack on an operating reactor were neglected, though not entirely ignored. Stimulated by Prime Minister Begin's assertion that the attack was timed before the reactor turned hot, which have caused a huge wave of radioactivity over the city of Baghdad and its innocent civilians, ( 1) the Congressional Research Service was asked for an evaluation. It reported that it would be most unlikely for the attack with conventional bombs upon the reactor to have caused lethal exposures in Baghdad, although some people at the reactor site might receive some exposure (2). Regrettably, the report, which may have steered Congress away from examining the issue more closely, may have underestimated the con­ sequences. Some adverse public health consequences might have resulted in Baghdad and its environs. For a review of the debate over whether destruction of the Iraqi reactor could have posed a hazard to Baghdad and its environs, see (3). In some respects, this fact is beside the point. Given the small size of the

Asymptomatic osteomyelitis of the symphysis pubis

Summary A patient presenting with pyrexia of unknown origin is described. Extensive radiological investigations over a six month period failed to localize an infective focus. Osteomyelitis of the symphysis pubis was found at post mortem. The clinical and radiological implications are discussed.

Invasion of the framework by laryngeal cancer. Surgical and radiological implications.

Invasion of the framework by laryngeal cancer. Surgical and radiological implications.

Sclerotic medullary spread in diaphyseal osteosarcoma

Dense medullary sclerosis is reported in the shafts of long bones accompanying diaphyseal osteosarcoma. Histological evidence suggests that this indicates more extensive medullary spread of tumour than is readily apparent on standard radiographic examination. It would appear that these sclerotic lesions show active radio-isotopes retention following skeletal scintigraphy. The clinical and radiological features and prognostic implications of these findings are discussed.

Radioactivity of building materials and the gamma radiation in dwellings

Measurements of the radioactivity in some common building materials in Norway are reported, together with calculations of the gamma -ray exposure from walls of different materials. Model rooms are used in calculations of the mean exposure inside concrete, brick and light-weight expanded clay aggregate buildings. These calculations give very good agreement with previous experimental results. The radiological implications of using building materials with high concentrations of radioactivity are also discussed.

Environmental aspects of tritium

The potential radiological implications of environmental tritium releases must be determined in order to develop a programme for dealing with the tritium inventory predicted for the nuclear power industry which, though still in its infancy, produces tritium in megacurie quantities annually. Should the development of fusion power generation become a reality, it will create a potential source for large releases of tritium, much of it in the gaseous state. At present about 90% of the tritium produced enters the environment through gaseous and liquid effluents and is deposited in the hydrosphere as tritiated water. Tritium can be assimilated by plants and animals and organically bound, regardless of the exposure pathway. However, there appears to be no concentration factor relative to hydrogen at any level of food chains analysed to date. The body burden, for man, is dependent on the exposure pathway and tissue-bound fractions are primarily the result of organically bound tritium in food.

Radiological Implications of Plutonium Recycle and the use of Thorium Fuels in Thermal Power Reactor Operations

The Central Electricity Generating Board reactor inventory code RICE has been used to calculate the buildup of activity and radioactive emissions for a range of alternative fuel cycles based on a conceptual high-temperature gas-cooled reactor design. The fuels included in this study were a conventional /sup 235/U-enriched oxide fuel, a mixed PuO/sub 2//UO/sub 2/ fuel employing pressurized water reactor plutonium, and both low- and high-enrichment mixed /sup 235/UO/sub 2//ThO/sub 2/ fuels. The results have been used to quantify the radiological protection implications of these fuel cycles in terms of fuel handling and reprocessing waste management.

Supported 242Cm in the marine environment

BOWEN and Livingston1 have reported the presence of 242Cm (half-life 163 d) in two samples of sea water which had been kept in sealed containers for 12 yr since the time of collection. Because the 242Cm originally present in the samples would have decayed completely after this period of storage, they suggested that the 242Cm which they detect is supported by a long-lived precursor, 242mAm; this radionuclide would not itself be detectable in these samples because of its much longer half-life (152 yr). They invited other workers in radiochemistry to search for similar evidence for 242mAm in the environment, and we have done so in some samples collected from the vicinity of the fuel-processing plant at Windscale where controlled discharges of transuranic nuclides to the marine environment are permitted under the provisions of the United Kingdom Radioactive Substances Act, 1960. The radiological implications of these discharges have been discussed by Hetherington et al.2.

Physiological and radiological implications of a low incidence of pineal calcification in Nigeria.

In a retrospective study of 952 skull X-rays taken in a few Lagos hospitals, it was found that the over-all incidence of calcification of the pineal gland was surprisingly low: 5.04% compared with the