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/couraged, although the trenches should still be capped with a flexibleimpervious material such as clay or asphalt capable of assuming themodified surface profile after the waste has settled. It is not usualto go to the added expense of providing a rigid concrete roofing forlow-level disposal trenches.The packaging is more important for the handling of waste thanfor its disposal, where minimal covering by waxed paper or plastichas sufficed at numerous disposal sites, and has resulted in negligiblemigration hazards. However, the more substantial packingssuch as drums and wooden boxes, sometimes used, have normallyreduced the voids volume by permitting the waste to be placed selectivelyand so the best use is made of the space available.(c)The type of wasteThe other feature that should be examined is the radionuclidecontent in the waste and the length of its half-life. Here it is of interestto note the proposals in the United Kingdom, where grounddisposal is practised only on a limited scale. It is suggested [53]that small quantities of waste should be permitted to be dischargedinto selected municipal refuse dumps. These dumps would be chosenwhere there was minimum risk to the contamination of water supplies.The amounts proposed are, however, very small, being less than100 /uCi per package for isotopes of half-life greater than one yearand 1 mCi per package if the half-life is less than one year. Incarrying out disposals the general limitations may be modified orexpanded to suit the kind of waste envisaged. An example of a typicalmodification is that the alpha-activity of any package should notexceed 1 mCi and that the main activity on the surface of unshieldedmaterial should not exceed 0. 1 nCi per cm2 of alpha activity or0. 75 R/h gamma radiation.Finally, it should be appreciated that waste normally destinedfor land burial includes not only low -level packages of juCi or mCicontamination, but large volumes of waste that are possibly radioactivebut generally not. Because of the expense of monitoring andsegregation it is disposed as low -level waste for convenience andthe result is that the mean level of contamination is very much lowerthan the limits given may suggest.44
This publication is not longer validPlease see http://www-ns.iaea.org/standards/VI.STANDARDS AND CONTROL TECHNIQUES(1) StandardsAny standards proposed for ground disposal are based mainlyon the primary return route to man by migration through sub-surfacewaters. The standards should be such that adequate health protectionis assured both to operating staff and to neighbouring communitiesand that all avenues of reconcentration in biological systems are recognized.The standards applied to effluent seepage concentrationsshould, in addition to meeting human requirements, be acceptablefor the subsequent re-use of the water by industry. Commercialundertakings may take water from downstream points in the hydrologicbasin; thus the residual contaminants should be within acceptableconcentrations at these water intakes. Although the limits arenot normally exacting in purity requirements, certain industries,for instance the photographic industry, are particularly sensitiveto changes in the background concentrations of radionuclides in theirwater supplies.Most problems in ground disposal are basically of a local nature.Ideally it would be useful to set contamination standards for the soil,taking into account the sorption phenomena relative to time and concentration.But because of the complex structure and inhomogeneityof most soils it is more realistic to work from the contamination levelsof the groundwater that are permissible at the point of emergence. Suchlevels can be derived from the Agency Basic Safety Standards [54]or the ICRP recommendations [55], taking into account such mattersas the use of the water, population densities, mineral resources,reconcentration in biological systems, and permissible body burden.General guidance in evaluation techniques for similar problemsis given in detail in the International Atomic Energy Agency1s Reportson "Disposal of Radioactive Wastes into Fresh Water" [56]and "Radioactive Waste Disposal into the Sea" [57].(2) ControlThe total volume of disposals to be permitted at a given siteneeds to be estimated. If the area is to be used solely for low-levelsolid waste, given reasonable soil and ground water conditions, thelimitation will probably be set by the size of the area as for any normalrefuse dump. For liquid disposals this may also be true if se45
Page 1 and 2:
This publication is not longer vali
Page 3: This publication is not longer vali
Page 6 and 7: This publication is not longer vali
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 ...

Create successful ePaper yourself

Delete template?

Save as template?