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1、BRITISH STANDARD BS 6068-3.1: 1993 ISO 9696:1992 Water quality Part 3: Radiological methods Section 3.1 Measurement of gross alpha activity in non-saline water: thick source method UDC 614.777:556.114.539.164 Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:29:45 GMT+00:00 2006, Uncontrolle
2、d Copy, (c) BSI BS 6068-3.1:1993 This British Standard, having been prepared under the direction of the Environment and Pollution Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 March 1993 BSI 08-1999 The following BSI references relat
3、e to the work on this Standard: Committee reference EPC/44 Draft for Comment 90/56330 DC ISBN 0 580 21642 X Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Environment and Pollution Standards Policy Committee (EPC/-) to Technical Committ
4、ee EPC/44, upon which the following bodies were represented: Association of Consulting Scientists British Association for Chemical Specialities British Gas plc Chemical Industries Association Convention of Scottish Local Authorities Department of the Environment (Water Directorate) Department of the
5、 Environment for Northern Ireland Department of Trade and Industry (Laboratory of the Government Chemist) Electricity Association Industrial Water Society Institute of Gas Engineers Institution of Water and Environmental Management Institution of Water Officers National Rivers Authority Royal Instit
6、ute of Public Health and Hygiene Royal Society of Chemistry Scottish Association of Directors of Water and Sewerage Services Soap and Detergent Industry Association Water Companies Association Water Research Centre Water Services Association of England and Wales The following bodies were also repres
7、ented in the drafting of the standard, through subcommittees and panels: AEA Technology Ministry of Agriculture, Fisheries and Food Ministry of Defence National Radiological Protection Board University of Manchester Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun
8、sheffieldun, na, Tue Dec 05 01:29:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6068-3.1:1993 BSI 08-1999i Contents Page Committees responsibleInside front cover National forewordii 1Scope1 2Normative references1 3Principle1 4Reagents1 5Apparatus2 6Sampling2 7Procedure2 8Expression of results3 9P
9、recision4 10Interference control5 11Regulations5 12Test report6 Annex A (normative) Total dissolved solids (TDS) dried at 180 C7 Annex B (informative) Bibliography8 Table 15 Table A.17 List of referencesInside back cover Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:29:45 GMT+00:00 2006,
10、 Uncontrolled Copy, (c) BSI BS 6068-3.1:1993 ii BSI 08-1999 National foreword This Section of BS 6068, which has been prepared under the direction of the Environment and Pollution Standards Policy Committee, is identical with ISO 9696:1992 Water quality Measurement of gross alpha activity in non-sal
11、ine water Thick source method. The International Standard was prepared by Technical Committee 147, Water quality, of the International Organization for Standardization (ISO) with the active participation and approval of the UK. BS 6068 is being published in a series of Parts subdivided into Sections
12、 that will generally correspond to particular International Standards. Sections are being, or will be, published in Parts 1 to 7, which together with Part 0, are listed below. Part 0: Introduction; Part 1: Glossary; Part 2: Physical, chemical and biochemical methods; Part 3: Radiological methods; Pa
13、rt 4: Microbiological methods; Part 5: Biological methods; Part 6: Sampling; Part 7: Precision and accuracy; Textual error. When adopting the text of the International Standard, the textual error given below was discovered. It has been marked in the text and has been reported to ISO in a proposal to
14、 amend the text of the International Standard. In 5.1, line 5, “their” should be read as “thin”. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard doe
15、s not of itself confer immunity from legal obligations. Cross-references International StandardCorresponding British Standard BS 6068 Water quality ISO 5667-1:1980Section 6.1:1981 Guidance on the design of sampling programmes (Identical) ISO 5667-2:1991Section 6.2:1991 Guidance on sampling technique
16、s (Identical) ISO 5667-3:19851)Section 6.3:1986 Guidance on the preservation and handling of samples (Identical) 1) A revision of ISO 5667-3 is in preparation. It is envisaged that this will be implemented in due course as a new edition of BS 6068-6.3. Summary of pages This document comprises a fron
17、t cover, an inside front cover, pages i and ii, pages 1 to 8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheff
18、ieldun, na, Tue Dec 05 01:29:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6068-3.1:1993 BSI 08-19991 WARNING The manufacturers instructions should be consulted with regard to the safe operating of high voltages used in counting equipment. In all countries strict regulations are issued to cover t
19、he use of radioactive materials in laboratories. These regulations are enforceable and the regulatory body should be contacted by prospective users. Specific instructions for the preparation of alpha sources are given in clause 7. 1 Scope 1.1 Substance determined This International Standard specifie
20、s a method for the determination of gross alpha activity in non-saline waters for alpha-emitting radionuclides which are not volatile at 350 C. It is possible to determine supported volatile radionuclides measured to an extent determined by half-life, matrix retention (of the volatile species) and t
21、he duration of measurement (counting time). 1.2 Applicability The method is applicable to raw and potable waters and can be extended to saline or mineralized waters, but with a reduced sensitivity. 1.3 Range of application The range of application depends on the amount of inorganic material in the w
22、ater and on the performance characteristics (background count rate and counting efficiency) of the counter. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the e
23、ditions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of curren
24、tly valid International Standards. ISO 5667-1:1980, Water quality Sampling Part 1: Guidance on the design of sampling programmes. ISO 5667-2:1991, Water quality Sampling Part 2: Guidance on sampling techniques. ISO 5667-3, Water quality Sampling Part 3: Guidance on the preservation and handling of s
25、amples1). 3 Principle The sample is acidified to stabilize it, evaporated almost to dryness, converted to the sulfate form and then ignited at 350 C. A portion of the residue is transferred to a planchette and the alpha activity measured by counting in an alpha-particle detector or counting system p
26、reviously calibrated against an alpha-emitting standard. 4 Reagents All reagents shall be of recognized analytical grade and shall not contain any detectable alpha activity. NOTE 1A method for preparing reagent blanks to check for endemic radioactivity or contamination is given in 10.1. 4.1 Standard
27、 solution, which shall be 241 Am. NOTE 2 241Am is preferred to 239pu, because the latter frequently suffers from the presence of 241Pu which leads to growth of 241Am in prepared standard solutions of sources, which would therefore need to be continually purified. A uranium compound of known isotopic
28、 composition is difficult to obtain and has a sensitivity different from that of 239Pu (see 9.3). NOTE 3Certified reference materials are available from several sources in most countries. The International Atomic Energy Agency (IAEA) Vienna, Austria is an international supplier. The National Institu
29、te of Standards Technology (NIST), USA can also supply to most countries. NOTE 4The choice of alpha standard will depend on a knowledge of the type of radioactive contaminant likely to be present in the waters being tested. In general, this amounts to a choice between naturally occurring and man-mad
30、e alpha emitters. NOTE 5A uranium compound of certified natural or known isotopic composition has one arguable advantage, in that its specific activity can be calculated from established physical constants and isotopic abundance data which are independent of the calibration procedures of a particula
31、r organization. NOTE 6Furthermore, since the energies of the alpha emissions from uranium isotopes are less than those from the artificial transuranic nuclides, the use of a uranium standard tends to give a high result for transuranics. Some authorities prefer to err on the high side in situations w
32、here the true composition is unknown. 4.2 Concentrated nitric acid, 50% (V/V). Dilute 100 ml 5 ml of nitric acid ( =1,42 g/ml) to 200 ml 10 ml with water (4.6). 4.3 Concentrated sulfuric acid, = 1,84 g/ml. 4.4 Volatile organic solvents, methanol and acetone. 4.5 Calcium sulfate Calcium salts may con
33、tain trace amounts of 226Ra and/or 210Pb and checks for the presence of these nuclides shall be made (see 7.7 and 10.1). 4.6 Water Distilled or deionized water shall be used for all applications. 1) To be published. (Revision of ISO 5667-3:1985) Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05
34、 01:29:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6068-3.1:1993 2 BSI 08-1999 5 Apparatus Usual laboratory apparatus and 5.1 Alpha counter Alpha activity shall be counted using either a silver activated zinc sulfide scintillation screen, a silicon surface barrier detector (SSB) or a proportion
35、al counter (windowless). lon-implanted Si detectors2) and their (u 100 4gcm2) window-proportional counters may also be used. If windowless systems are used, carry out checks for possible contamination of the counting system by counting a blank sample between each source counted. NOTE 7The particulat
36、e nature of the source to be counted may give rise to contamination problems if operated in a vacuum (as in the case of an SSB) or gas flow systems (as used in a proportional counter). 5.2 Planchettes (counting trays), of thickness at least 2,5 mgmm2 (250 mgcm2). These shall be lipped and of stainle
37、ss steel. NOTE 8The diameter of the planchette to be used is determined by the counter requirements, i.e. the detector diameter and source holder dimensions. NOTE 9An evenly spread source is required and some workers find it easier to produce this on a polished metal surface, whereas others prefer t
38、o use an etched or roughened planchette (sand blasting and chemical etching have been applied for this purpose). 5.3 Muffle furnace, capable of maintaining a temperature of 350 C 10 C. 6 Sampling Add 20 ml 1 ml of nitric acid (4.2) per litre of sample to be collected to a clean polythene bottle and
39、then collect the sample in accordance with ISO 5667-1, ISO 5667-2 and ISO 5667-3. Store at a temperature of 4 C 4 2 C and analyse the sample as soon as possible after collection. Carry out filtration immediately on collection and before acidification, if it is desired to measure the activity of the
40、filtered sample of water. NOTE 10Acidification will minimize the loss of radioactive material from solution by absorption. If carried out before filtration, it will desorb radioactive material already absorbed on the particulate material. 7 Procedure 7.1 Preliminary NOTE 11The analysis should be car
41、ried out in an area where radio-tracers are not used. Determine the total solids content of the water according to Annex A . Making due allowance for changes in composition due to ignition at 350 C and sulfation of the residue, calculate the volume of sample required to produce a mass of solid resid
42、ue slightly in excess of 0,1A mg (where A is the area of the planchette (5.2)in square millimetres). Use this as a guide to the volume of sample required for the concentration stage which follows. 7.2 Concentration stage Transfer to a beaker a measured volume V, in litres, ( 1 %) of the sample (see
43、clause 6) chosen such that after ignition there is at least 0,1A mg of residue. NOTE 12With very soft waters, it is possible that the volume required to produce 0,1A mg is impractically large. In these circumstances, the largest practicable volume should be used. (See also note 14.) Evaporate carefu
44、lly on a hot-plate until the volume is reduced to about 50 ml and allow to cool. Transfer the concentrated solution to a weighed silica (or glazed porcelain) dish, previously ignited at 350 C. Wash the beaker carefully with a minimum quantity of water (4.6) and transfer the washings to the dish. NOT
45、E 13If the beaker is large, it may be convenient to transfer the washings to a smaller beaker. The washings can then be concentrated to a low bulk to facilitate transfer to the silica dish. 7.3 Sulfation stage Ensure that the washings in the dish are cool and add 1 ml ( 20 %) of sulfuric acid (4.3).
46、 NOTE 14Some water may, on drying and ignition, produce a residue which is unsuitable for the measurement of radioactivity, because it is hygroscopic or difficult to disperse. This sulfation process is a suitable treatment for many such samples. The volume of sulfuric acid chosen is capable of sulfa
47、ting about 1,8 g of calcium carbonate. To allow for an excess of acid, the initial volume of sample should be chosen such that the total solids content does not exceed 1 g. (Experience with some waters may show this step to be unnecessary.) Carefully evaporate the contents of the dish to dryness. To
48、 avoid spitting, expose the dish to heat from above (from an infrared lamp) and continue heating until fumes of sulfuric acid are evolved. Then transfer the dishes to a hot-plate and continue heating until no further fumes are evolved. 7.4 Ignition stage Transfer the dish and contents to the muffle
49、furnace (5.3), ignite for 1 h at a temperature of 350 C 10 C and allow to cool in a desiccator. Note the time and date of removal from the furnace. Weigh the dish and residue and obtain by difference the mass m, in milligrams, of the ignited residue. 2) See national foreword for details of textual error. Licensed Copy: sheffieldun sheffieldun, na, Tue Dec 05 01:29:45 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6068-3.1:1993 BSI 08-19993 7.5 Source preparation Weigh 0,1A mg ( 1%) of the ash onto a planchette