Safety_Series_041_1975 - gnssn - International Atomic Energy ...

More documents

Recommendations

Info

This publication is no longer valid Please see http://www.ns-iaea.org/standards/ 122 APPENDIX IV maximum degree of radiological exposure is trivial at this stage, equivalent to a m ere 0.07% of the derived working lim it, it marks an important step in environmental measurements. A sim ilar series of calculations can be carried out for contamination of beach material, for which the only important nuclides are caesium-137 and -134. The maximum conceivable exposure by this route is even less than by consumption of fish and shrimps, at 0.02% of the derived working limit. (C) Exposure not measurable by any method Dilution of discharges from some sites is so large compared with the quantities of radioactivity involved that it can be predicted with confidence that no environmental material will be measurably contaminated. Although there may be little or no scientific need to carry out any environmental monitoring, a limited program me is generally undertaken, at least in the early period of operation of a site, prim arily to allay public fears. Ultimately, the program m es can be contracted, and if this situation of no measurable contamination persists after the station has reached operational equilibrium, it will be possible to dispense with monitoring altogether, leaving any occasional checks to the operator. A good example of this type of site is provided by the nuclear power station at Dungeness, Kent. Radiological exposure is not measurable by any method, direct or indirect, but monitoring is still designed on the critical path model which provides the only meaningful and scientific basis for expressing results. Detectable contamination is not necessary before potential critical routes can be identified. Two groups of the public would be important in this way — fishermen and bait-diggers — and the monitoring program me is designed to cover their habits. Plaice and whelks are sampled at approximately quarterly intervals subject to seasonal availability, and a simple total beta assay is sufficient to show that no artificial radioactivity is present. Occasionally, samples are analysed by gam m a-spectrom etry to confirm that no radionuclides are being m issed by the m ore simple beta analysis. Bait-digging for lugworm is a regular occupation on the beaches to the east of the power station and the potential critical effect would be external gamma radiation exposure resulting from adsorption of radioactivity on to the fine sand in this area. To cover this pathway gamma d oserate measurements are made at selected points from half a m ile to four m iles from the discharge point. Measurements have so far
This publication is no longer valid Please see http://www.ns-iaea.org/standards/ APPENDIX IV 123 revealed nothing but natural radioactivity, principally of cosm ic origin. A series of measurement positions is adopted, prim arily so as to have a basis for proving whether any apparent contamination could be attributed to the station. This would only be so if m easurements were made at quarterly intervals during the first three years of operation of the station, after which they were reduced to the present rate of two surveys per year, which reflects the expected trend in a situation of this type. UNITED STATES OF AMERICA Typical surveillance program m es [24] Environm ental m onitoring around fa cilities handling uranium Tsivoglou [25] has described the environmental monitoring program me around a uranium m ill in Colorado. Little airborne wastes are generated at this m ill since waste gases from furnaces and other equipment are generally scrubbed to rem ove particulates before release to the atmosphere. Samples of river water and sediment are collected from the river where the liquid wastes are discharged. Water samples upstream and downstream of the mill are taken by means of a pump and tim er set to deliver a small volume of water every 15 minutes to a large collection bottle. Samples are rem oved weekly and either analysed weekly or com posited for monthly analysis. Analysis is principally for radium-226 and uranium, although analyses for 210Pb, Th and Po have been made on a few samples. Sediment samples are analysed for 226Ra and gross alpha activity. Radium-226 was determined by the radon emanation technique, uranium by fluorom etric procedure and gross alpha activity with an internal proportional counter. Quantities of uranium are released to the atmosphere from several stacks of the Springfield Works (a fuel fabrication plant) near Preston, Lancs, UK [26]. Traces of the released uranium may deposit on vegetation grazed by cattle. Since uranium ingested by cows is not transferred to their milk, the main criteria is protection of the health of the animals rather than human radiation exposure. Samples of bovine faeces were collected twice during 196 9 from four farms close to the Springfield site and from a central farm several m iles away.3 In all but one case samples contained 5 /Ltg of uranium 3 T h e sam p ling o f bovine fa eces began in 1962. T h e c o n ten t o f uranium was g en era lly in the range 0 - 5 ppm above re fere n ce sam ples tak en at a d istan ce o f about ten m ile s.
Page 1 and 2:
This publication is no longer valid
Page 3 and 4:
Page 5 and 6:
Page 7 and 8:
Page 9 and 10:
Page 11 and 12:
Page 13 and 14:
Page 15 and 16:
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
Page 27 and 28:
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
Page 59 and 60:
1M|137CJ g 1 litre 134Cs C 3 .5 lit
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86: This publication is no longer valid
Page 101 and 102: T A B L E X V I (con t.) This publi
Page 109 and 110: T A B L E X V III (con t.) This pub
Page 113 and 114: T A B L E X X (con t.) This publica
Page 135: This publication is no longer valid
show all

Safety_Series_041_1975 - gnssn - International Atomic Energy ...

Create successful ePaper yourself

Delete template?

Save as template?