[en] The paper describes a method which permits the integration of information from multiple domains in the assessment of resources. Maps displaying different attributes from multiple domains (e.g. geology, geophysics, geochemistry, remote sensing) are evaluated individually and partitioned in terms of the objective into favourable regions (aggregate of areal units) which are coded '1'; the remaining regions of uncertain significance are coded '0'. For some variables (e.g. geochemical and remote sensing) the spatial concept of 'anomalous' region, defined as any area 'higher' than its surrounding areas, can be used to delineate favourable regions. Binary surfaces generated for each of the geochemical, geological and geophysical variables available within a province of interest are evaluated within a model area and relative weights are calculated for each variable. The computed weights assign levels of importance to the component variables or characteristics of the model. Binary maps for the different domains are then combined into one map which expresses the degree of association between a given areal unit and the model, taking into account the relative weights or importance of the respective variables which characterize the model. An example of the use of weighted characteristic analysis with geological, geophysical and remote sensing variables showed the ability of the method to delineate areas with known mineralization when it was tested in a well-explored area in Norway. (author)

[en] Growing awareness that the era of cheap energy is over has led to current efforts by governments and international organizations to examine the question of the adequacy of energy resources on a global scale. Despite the relative success of the NEA and the IAEA efforts in the study of world uranium supply, there is a need for such studies to become still more comprehensive and broader in scope. A basic problem exists with respect to the lack of a universally accepted set of resource terms by which to classify resource estimates once they are made. Often voids exist in international assessments because of insufficient data with respect to known resources and occasionally because of a lack of expertise to make the required estimates. With respect to the assessment of undiscovered uranium resources, major constraints are the relatively embryonic state of methodology for assessment of undiscovered resources and the fact that the inventory of basic geology, geochemical, and geophysical data is either incomplete or non-existent in many parts of the world. Finally, once resource estimates are made, there is often an unclear understanding about when and at what rate the resources can be made available. Hopefully, current efforts will lead to a solution to some of the principal problems and constraints which may be impeding progress toward an expansion and improvement of world uranium resource assessments. (author)

[en] Estimation of undiscovered uranium resources as conducted by the Uranium Resources Evaluation Section of the Geological Survey of Canada is based: (a) on geological analyses of areas containing known uranium deposits, their past production and identified reserves; (b) on an assumption that economic geological features of known or control areas can be extrapolated to areas with similar geological environments; and (c) on conceptual genetic models simulating processes leading to formation of specific types of uranium mineralization. Several computation methods, such as volumetric, geostatistical and MIMIC (Mining Industry Model for Inventorization and Cost Evaluation) are used routinely with various degrees of completeness, or have been experimentally applied to selected areas. Two basic computerized files are used for storage and retrieval of economic geological parameters: (1) Uranium CANMINDEX, comprising information on location, character and references of individual uranium occurrences and (2) URE-3 file, containing information on geology and uranium mineralization of selected areas in Canada. The undiscovered uranium resources are classified into two categories: (1) Prognosticated Resources which comprise estimated undiscovered uranium tonnages in known uranium districts beyond specific limits established for inferred ore and (2) Speculative Resources which comprise estimated tonnages in areas where only occurrences are known or in virgin areas. (author)

[en] This paper aims at offering a very intuitive and a rather global presentation of the basic ideas and basic techniques of geostatistics. The examples which have been chosen for the illustration of the various methods are especially suitable for uranium deposits. Two problems have been dealt with in depth: the optimization of sampling patterns and the best estimation of the block grade. (author)

[en] This paper explains the need for long-range forecasting of the adequacy of uranium supplies, to guide Research and Development strategy in the field of nuclear power. It describes the progress made in estimating world uranium resources using geological data, but concludes that it will never be economic to mount prospecting programmes which give more than about a ten-year view. The paper then describes various statistical methods used to give a longer-term view of world uranium resources but points to the need to broaden their statistical base. It concludes that the uncertainty of world-wide uranium occurrence as well as its long-term availability to the UK argues for a flexible R and D strategy, keeping open as many options as possible in reactor and fuel cycle design, and particularly in continued development of the fast reactor. The alternative is to risk severe increases in the cost of electricity in the UK towards the end of the century as fossil fuels and then uranium become scarce. (author)

[en] By the late 1960s enough was known about the Gas Hills uranium district to allow a reasonable estimate of the U₃O₈ that ultimately would be recovered from the district. Five essential elements contributed to making the estimate: (1) extent of the favourable facies of the host rock; (2) character of the orebodies; (3) unity of the Gas Hills district: the West, Central, and East Gas Hills are all part of a single large geologic feature; (4) direction of flow of the mineralizing solutions; and (5) history of the mining and exploration in the district. Using the four geologic factors to make the estimate led to a value more than double that of the previously estimated resources and allowed identification of areas that are favourable and unfavourable for exploration. The new estimate indicated that between 150 and 200 million lb of U₃O₈ would be recovered from the Gas Hills district and that, with a substantial increase in the price of U₃O₈ recovery would approach 200 million lb. Continued exploration in the Gas Hills has led to discovery of additional ore in areas thought to be favourable for its occurrence, and the recent increases in the price of U₃O₈ have converted to ore material that previously was of too low a grade to mine economically. These two factors have increased the amount of U₃O₈ that will be recovered from the Gas Hills to about 200 million lb; ultimate production from Tertiary rocks in the Gas Hills, however, cannot greatly exceed this amount. (author)

[en] A computer program is described that estimates the amount of uranium that will be produced from a mine as a co-product of gold subject to a changing economic environment. The program makes use of two models. The first simulates activities underground, whereas the second simulates the performance of processing plant on the surface. The combination of these models generates a description of the flow of ore from stopes and from development, through hoisting, sorting, and the metallurgical plant to the despatch of saleable product. The total production of uranium to the end of the life of the mine constitutes the uranium reserve. The effects on production forecasts and reserve estimates of future trends in cost and price factors are illustrated by results generated from the application of the program to a typical South African mine producing gold and uranium. The graphs presented show that South Africa's future uranium production from underground sources is critically dependent on the gold price in the years ahead. (author)

[en] Nuclear generating capacity is projected to grow from the current level of about 80 GW(e) to over 1500 GW(e) by the year 2000, primarily through installation of converter reactors. Annual fuel requirements are projected to grow from the current level of around 25,000 short tons U₃O₈ to almost 200,000 by the year 2000. Such an expansion can be realized only if there is timely identification of uranium resources. Reasonably assured resources at US $30 per pound U₃O₈ have been estimated at 2.4 million short tons U₃O₈ and estimated additional resources at the same cost total about the same amount. These resources are predominantly concentrated in only a few countries of the world where most of the exploration has been carried out. It is therefore reasonable that as additional field information is developed and efforts directed toward resource appraisal are extended into more countries, the results will be higher estimates of world uranium resources. Information available on uranium resources is probably more complete and of a better quality than for any other metal but there is room for improvement. Consistent approaches and terminology are highly desirable and it would be of great benefit if reserve estimates were accompanied by specific explanation of criteria used in analysis. Increasing costs, inflation, and rising prices especially complicate consistent reserve estimates. The world-wide concern over uranium resources and the trend to long-range planning has increased interest in methodology for appraising undiscovered resources. Better understanding of the needs and purposes of resource appraisal and the methods and terminologies used may ultimately result in a more comprehensive and aggressive effort to develop new data and approaches to assure a better understanding of the uranium resource base

[en] The factors affecting co-product uranium ore reserve estimates for producing and potential new South African gold mines are reviewed as well as the models which can assist in improving the estimation procedures. It is shown that it is essential to use a joint pay limit and to arrive at unbiased ore reserve estimates via regression or kriging techniques. The joint pay limit approach, in turn, emphasizes that uranium reserves are dependent not only on uranium production costs and revenue, but also on the corresponding gold revenue and gold mining costs. (author)

[en] Well-founded estimates of the rate at which a country's resources might be made available are a prime requisite for energy planners and policy makers at the national level. To meet this need, a method is discussed that can aid in the analysis of future supply patterns of uranium and other metals. Known sources are first appraised, on a mine-by-mine basis, in relation to projected domestic needs and expectable export levels. The gap between (a) production from current and anticipated mines, and (b) production levels needed to meet both domestic needs and export opportunities, would have to be met by new sources. Using as measuring sticks the resources and production capabilities of typical uranium deposits, a measure can be obtained of the required timing and magnitude of discovery needs. The new discoveries, when developed into mines, would need to be sufficient to meet not only any shortfalls in production capability, but also any special reserve requirements as stipulated, for example, under Canada's uranium export guidelines. Since the method can be followed simply and quickly, it can serve as a valuable tool for long-term supply assessments of any mineral commodity from a nation's mines. (author)