Safety_Series_015_1965 - gnssn - International Atomic Energy ...

More documents

Recommendations

Info

This publication is not longer validPlease see http://www-ns.iaea.org/standards/Probable variations in the ground water path should be examined;for instance, if a gravity aquifer is shallow the flow path would beinfluenced significantly by the lower boundary profile and thereforemore susceptible to variation with the recharge rate. Flow pathsin deep aquifers, conversely, would be less influenced by variationsin recharge rate.The time of passage for ground water to traverse the possibleroutes will have to be estimated and this is probably one of the mostdifficult yet important facets of the investigation. Without an estimateof the travel time it will be impossible to assess the probableretention of migrating radioactive ions.(3) Geology and sub-surface investigationIt is axiomatic that no investigation of aquifers can be completewithout a thorough understanding of the associated geological features[10,11]. To examine precisely the successive; horizons ofstrata, samples of geological materials must be collected and examined.The objects of such investigations, for the special requirementsof waste disposal, are directed towards the permeability ofthe various formations [12] and the isolation of their mineralogicalcomponents for sorption and ion-exchange measurements. For consolidatedrock, the conventional method of rotary drilling and theextraction of core samples is sufficient for these purposes. Forthe permeable sedimentary rocks, physical examination of undisturbedsamples and permeability checks may be carried out; whereasfor the intrinsically impermeable rocks, water flow is restrictedto fissures whose presence may be revealed only by in-situmeasurement.The investigation of unconsolidated and granular deposits maybe undertaken by conventional methods of drilling but sampling re quirements may be different in order to secure specimens suitablefor non-standard examination. In soils that are partially dry,a boreholemay be sunk by means of a churn drill or auger, and conventionalsampling carried out with tools appropriate for the type of soil.Those that have a large range of particle sizes, e. g. gravels, aredifficult to sample except in a disturbed state by auger or bailer, andreconstituted samples of such soil may be the best that can be obtainedfor examination. Where the soils are sorted into smaller,more uniform grain size, e.g. sands, it is sometimes better to usewashboring methods and certainly preferable to sample in the un
This publication is not longer validPlease see http://www-ns.iaea.org/standards/d isturbed state r e g a rd le s s o f w hether the s o il is d ry o r saturated.A visu al exam ination of undisturbed sam p les would indicate the h om ogeneity of the soil o r whether it was obviously com posed of su cce ssiv e lam inations of contrasting w e ll-sorte d soil. An exam ple ofthe lam inated type of stru ctu re, a coh esion less fine sand containingle s s than 5% silt, is shown in F ig. 1. Such ob servation s are n e c e s sa ry when the p erm ea b ility o f the m edium is one of the p rin cip a ldetails sought fro m the in vestigation .F ig -1Cross-section through an undisturbed sam ple o f lam inated sand.L am inated m a teria ls have d ifferen t p e rm e a b ilitie s a cco rd in gto the d ire ctio n o f w ater flow and are term ed a n isotro p ic. Whensam p les o f undisturbed granular s o ils are tested fo r p erm ea b ilityin the laboratory, water is passed along the axis of each cylin d rical9
Page 1 and 2: This publication is not longer vali
Page 3: This publication is not longer vali
Page 68 and 69:
This publication is not longer vali
Page 70 and 71:
Page 72 and 73:
Page 74 and 75:
Page 76 and 77:
Page 78 and 79:
Page 80 and 81:
Page 82 and 83:
Page 84 and 85:
Page 86 and 87:
Page 88 and 89:
Page 90 and 91:
Page 92 and 93:
Page 94 and 95:
Page 96 and 97:
Page 98 and 99:
Page 100 and 101:
Page 102 and 103:
Page 104 and 105:
Page 106 and 107:
Page 108 and 109:
Page 110 and 111:
Page 112 and 113:
Page 114 and 115:
Page 116 and 117:
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
Page 124:
show all

Safety_Series_015_1965 - gnssn - International Atomic Energy ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?