PRELIMINARY CONS IDS* AT IONS OP THE USE OP RADIOISOTOPES 



FOR LABORATORY TRACER TECHNIQUES 



by 



Norman E. Taney, Chief 

 Geology Branch, Engineering Division 

 and Radiological Control Officer 

 Beach Erosion Board 

 U. S. Army Corps of Engineers 



An investigation of the feasibility of utilizing radioactive tracers in 

 laboratory studies of sediment movement has been in progress for the past sev- 

 eral years at the Beach Erosion Board. The preliminary results of this investi- 

 gation are presented herein. 



The responses of beach and bottom sediments to wave and current energy are 

 incompletely understood, and many facets of these complex phenomena are dealt 

 with empirically. It is necessary, therefore, to measure the resultants of 

 the interaction of sea energy and the shore upon which it impinges to augment 

 our fund of knowledge and solve practical problems. Such measurements, however, 

 may be most difficult to acquire. 



The measurement of direction, velocity and quantity of sediments moving in 

 the littoral zone may be quite complex, particularly in areas where there are 

 no structures which block essentially all sediment movement. It is, therefore, 

 most desirable to mark sediments or simulated sediments in some fashion which 

 will permit convenient and rapid identification of the labelled particles. 

 A method which has been developed in the past decade involves the use of radio- 

 isotopes. The radioactive material is fastened on or in the sediment or simul- 

 ated sediment and the quanta emitted are detected by some suitable means. Such 

 a procedure is most advantageous in that the particles are in their normal en- 

 vironment and respond normally to the forces applied. Detection of the particles 

 is possible on subsequent days and thus a time-space history of the particles 

 may be developed. Such a program is based upon the positive identification of 

 the radioactive emissions and may be pursued without a laborious and expensive 

 bottom sampling program. This does not mean that bottom samples are not required, 

 rather it means that the expensive, time-consuming acquisition of samples is 

 minimized 



Labelled sedimentary particles may also be used advantageously in the 

 laboratory. At the Beach Erosion Board the Shore Processes Test Basin is a 

 facility which could be utilized for radioactive tracer techniques. It is 

 a shallow concrete structure 300 feet long, 150 feet wide and 3 feet deep. At 

 present the basin is divided into three parts for three concurrent tests. 

 Figure 1 illustrates a typical test layout in one section of the basin. The 

 wave generating machines are synchronized so that a single wave leaves the 



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