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Radioactive Testing of Rust Preventives

Radioactive Testing of Rust Preventives By Dr. W. Summer The author describes a quick and reliable method of testing rust preventives which employs chemicals tagged with radioactive tracers. He includes also a note on handling and health hazards so that the necessary precautions can be taken when using the technique. HE efficiency of a rust-preventive If an inherent radioactivity (background) the gamma radiation) and a specific activity composition depends upon how well of N counts is present, the radioactivity approximately 1,500 times less than that it removes water from the metal surface of the tagged water is indicated by NRA, of sodium. treated. In testing rust preventives to the difference N - N will indicate the The staying power and evenness of dis­ RA B ascertain their dewatering properties, the residual activity N and the reciprocal tribution of a protective layer can be usual chemical methods of detection are investigated by preparing the phosphate inconvenient for a number of obvious value will be a measure of the rust- solutions with radioactive P32 or admixing reasons. An accelerated, or standard time, a P32-containg tracer to the rust preventive. weathering test may give, in the former The characteristic data of P32 are: preventing power. instance, unreliable results or, in the latter Half-life 14 days 8 hr. Precautions case, take up too much time before reliable Beta energy 1.69 mev. results are obtained. The use of radioactive materials neces­ Specific activity 2.6 mc./g. Pric e (one week) £2 sitates precautions additional to those Th e radioactive tracer technique will be usually taken in chemical laboratories. It found extremely useful, as it gives an Approximately 20 different compounds is particularly the radiation hazard which containing radioactive phosphorus can be immediate and reliable measure of the will call for concentrated attention to the obtained from Amersham. amount of residual water. A minute quan­ problems of storage, handling and dis­ tity of a suitable radioactive isotope is Handling and health hazards persal of waste radioactive material. Pro­ mixed with the water into which the metal duction of radioactive substances is so far is dipped or immersed. After a time, the In handling Na24 and S35 compounds advanced that the research worker has a rust preventive is applied in the normal great care should be taken to provide considerable variety of chemicals at his way. The treated metal panel is then adequate shielding. If it were not for the disposal. In addition to their different tested with a particle counter for any gamma energy of sodium24, 1 cm. of glass chemical characteristics, these chemicals radiations that might be emitted from the or Perspex would give adequate protection. have a variety of radiation characteristics, panel. The count will be inversely pro­ Taking the gamma radiation into account, so that selecting an appropriate substance portional to the protective quality of the 8 cm. of glass or Perspex are essential. for any one special application is an easy rust preventive and can be easily expressed Up to and including 10 μc, i.e. 0.5 g. matter. as a number which may be inversely of S35, a pure beta emitter, can be handled proportional to the count. This number Economy is a next consideration, because in ordinary chemical laboratories. For can be made the discriminating charac­ it involves the type of material and test. stronger and, especially, for gamma emit­ teristic and be used for purposes of As the radiation has only very thin layers ters, separate laboratories and special classification. to penetrate, a low-energy emitter will be arrangements must be provided. ideal. Its energy should be a maximum Technique during the test period, but decay fairly rapidly after. This will go far in solving the A quantity of a tagged substance, suf­ problems of storage and disposal. ficiently minute so as to have no, or no appreciable, chemical effect on the materials Data on radioactive materials under test, is dissolved in water. Both the water into which the metal panel will be The characteristics of the two most submerged and the metal itself must be useful radioactive materials are: tested for any inherent radioactivity which, Sodium24 Sulphur35 if present, will form the background count. Half life 14 hr. 54 min. 87 days 2 hr. Then a quantity of Na24Cl, Na 24C0 , 24 min. 2 3 Beta energy 1.39 mev. 0.168 mev. H S35O , or other radioactive substances 2 4 Specific activity is dissolved in water and the radioactivity (one week) 32 mc./g. 2 2 μc./g. is measured. The test object is then Price (one week) £2/1 0 g. £2/2 0 g. immersed and left in the water for some A comparison shows that sodium com­ time. It is advisable to stir the water or pounds are the ideal materials for the make quite sure by other means that the laboratory. The half-life is short, which radioactive water penetrates into any cracks makes for easy and safe disposal of waste and fissures or pinholes and pits there may products; the energy of the beta radiation be. The metal panel is then treated in the is considerable, and so is the specific usual way as set out in the ' directions for activity, giving, in an irradiation unit of use ' issued by the manufacturers of the 10 g. (as supplied by the Radiochemical rust preventive. Centre, Amersham, Bucks), a total activity of 320 mc. This makes for easy detection When the preparation of the panel has even of minutest quantities. Sodium24 been completed, which, in all cases, means that no trace of water has been left behind also emits gamma radiation of 2.76 and and is hidden under the layer of rust pre­ 1.38 mev. ventive, the particle counter is again passed Sulphur has a long half-life, a beta over the test object to detect the radio­ emission approximately one-eighth of that activity of the residual water, if any. of Sodium21 (calculated without considering 144 CORROSION TECHNOLOGY, July 1954 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Anti-Corrosion Methods and Materials Emerald Publishing

Radioactive Testing of Rust Preventives

Summer, W.
Anti-Corrosion Methods and Materials , Volume 1 (5): 1 – May 1, 1954
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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0003-5599
DOI
10.1108/eb018939
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Abstract

By Dr. W. Summer The author describes a quick and reliable method of testing rust preventives which employs chemicals tagged with radioactive tracers. He includes also a note on handling and health hazards so that the necessary precautions can be taken when using the technique. HE efficiency of a rust-preventive If an inherent radioactivity (background) the gamma radiation) and a specific activity composition depends upon how well of N counts is present, the radioactivity approximately 1,500 times less than that it removes water from the metal surface of the tagged water is indicated by NRA, of sodium. treated. In testing rust preventives to the difference N - N will indicate the The staying power and evenness of dis­ RA B ascertain their dewatering properties, the residual activity N and the reciprocal tribution of a protective layer can be usual chemical methods of detection are investigated by preparing the phosphate inconvenient for a number of obvious value will be a measure of the rust- solutions with radioactive P32 or admixing reasons. An accelerated, or standard time, a P32-containg tracer to the rust preventive. weathering test may give, in the former The characteristic data of P32 are: preventing power. instance, unreliable results or, in the latter Half-life 14 days 8 hr. Precautions case, take up too much time before reliable Beta energy 1.69 mev. results are obtained. The use of radioactive materials neces­ Specific activity 2.6 mc./g. Pric e (one week) £2 sitates precautions additional to those Th e radioactive tracer technique will be usually taken in chemical laboratories. It found extremely useful, as it gives an Approximately 20 different compounds is particularly the radiation hazard which containing radioactive phosphorus can be immediate and reliable measure of the will call for concentrated attention to the obtained from Amersham. amount of residual water. A minute quan­ problems of storage, handling and dis­ tity of a suitable radioactive isotope is Handling and health hazards persal of waste radioactive material. Pro­ mixed with the water into which the metal duction of radioactive substances is so far is dipped or immersed. After a time, the In handling Na24 and S35 compounds advanced that the research worker has a rust preventive is applied in the normal great care should be taken to provide considerable variety of chemicals at his way. The treated metal panel is then adequate shielding. If it were not for the disposal. In addition to their different tested with a particle counter for any gamma energy of sodium24, 1 cm. of glass chemical characteristics, these chemicals radiations that might be emitted from the or Perspex would give adequate protection. have a variety of radiation characteristics, panel. The count will be inversely pro­ Taking the gamma radiation into account, so that selecting an appropriate substance portional to the protective quality of the 8 cm. of glass or Perspex are essential. for any one special application is an easy rust preventive and can be easily expressed Up to and including 10 μc, i.e. 0.5 g. matter. as a number which may be inversely of S35, a pure beta emitter, can be handled proportional to the count. This number Economy is a next consideration, because in ordinary chemical laboratories. For can be made the discriminating charac­ it involves the type of material and test. stronger and, especially, for gamma emit­ teristic and be used for purposes of As the radiation has only very thin layers ters, separate laboratories and special classification. to penetrate, a low-energy emitter will be arrangements must be provided. ideal. Its energy should be a maximum Technique during the test period, but decay fairly rapidly after. This will go far in solving the A quantity of a tagged substance, suf­ problems of storage and disposal. ficiently minute so as to have no, or no appreciable, chemical effect on the materials Data on radioactive materials under test, is dissolved in water. Both the water into which the metal panel will be The characteristics of the two most submerged and the metal itself must be useful radioactive materials are: tested for any inherent radioactivity which, Sodium24 Sulphur35 if present, will form the background count. Half life 14 hr. 54 min. 87 days 2 hr. Then a quantity of Na24Cl, Na 24C0 , 24 min. 2 3 Beta energy 1.39 mev. 0.168 mev. H S35O , or other radioactive substances 2 4 Specific activity is dissolved in water and the radioactivity (one week) 32 mc./g. 2 2 μc./g. is measured. The test object is then Price (one week) £2/1 0 g. £2/2 0 g. immersed and left in the water for some A comparison shows that sodium com­ time. It is advisable to stir the water or pounds are the ideal materials for the make quite sure by other means that the laboratory. The half-life is short, which radioactive water penetrates into any cracks makes for easy and safe disposal of waste and fissures or pinholes and pits there may products; the energy of the beta radiation be. The metal panel is then treated in the is considerable, and so is the specific usual way as set out in the ' directions for activity, giving, in an irradiation unit of use ' issued by the manufacturers of the 10 g. (as supplied by the Radiochemical rust preventive. Centre, Amersham, Bucks), a total activity of 320 mc. This makes for easy detection When the preparation of the panel has even of minutest quantities. Sodium24 been completed, which, in all cases, means that no trace of water has been left behind also emits gamma radiation of 2.76 and and is hidden under the layer of rust pre­ 1.38 mev. ventive, the particle counter is again passed Sulphur has a long half-life, a beta over the test object to detect the radio­ emission approximately one-eighth of that activity of the residual water, if any. of Sodium21 (calculated without considering 144 CORROSION TECHNOLOGY, July 1954

Journal

Anti-Corrosion Methods and Materials – Emerald Publishing

Published: May 1, 1954

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