grains in one of several fashions: either the grains would be moved in the 

 direction of the longshore drift or in the offshore direction, or other grains 

 would cover the stationary irradiated glass particles. In this fashion there 

 would be dispersal of the activated grains and dilution of those particles by 

 non-activated sand grains. Another factor would be the relatively rapid decay 

 of any of the tracer elements chosen for this type test. For a 1-week testing 

 program for instance, in 1 day the activity would be reduced to less than half 

 of the original activity present. Another factor is the physical conditions 

 of the test. The arrangements are such that at no time would personnel be re- 

 quired to walk on the sandy beach nor would it be necessary for personnel to 

 be closer than 1 meter to the area where the activated material was placed. 

 Finally the time required for necessary measurements during the course of the 

 test is small, probably on the order of 1 hour per day or less. In this fashion 

 natural decay, time, distance, and dispersal of the particles all tend to reduce 

 potential hazards. 



The evaluation of potential hazard has been made by the method suggested 

 in a paper by Hubbell, Bach and Lamkin. The conditions which would exist in- 

 volve the utilization of 50 millicuries of sodium (N a ) dispersed uniformly 

 over an area 1.5 feet wide by 30 feet long. As it is desirable to evaluate the 

 hazard under the worst conditions, it has been assumed that no water, which 

 would act as a shield, covers the radioactive particles. Further, the evalua- 

 tion was made for that time when the irradiated glass has just been placed upon 

 the beach. The reasoning behind this assumption is that the activity would 

 rapidly decay as the test started and continued, and there would be dispersal 

 of the activity. The evaluation is basically a problem of summing up the con- 

 tributions from all of the photons emitted by the irradiated particles which 

 reach the detector and then converting this energy to dose at the position of 

 the detector. The dose has been calculated for a detector positioned at an ele- 

 vation of 3 feet above beach level, the height most commonly considered if 

 personnel will be affected. 



The dose rate was first calculated with the position of the detector 3 

 feet above the center of the rectangle. The summation is facilitated by the 

 use of a Legendre expansion which takes the form: 

 I ~ A q 



+ (A Q - A^ q x T 



< A o 



- 2Aj^ + 2 ' 



lA 2 )q 2 T2 







< A o 



- 3A X + 3 ' 



' 2 A 2 - 3 



• 2 * 



1 A 3 ) q 3 T 3 



< A o 



- 4A X + 4 ' 



' 3 A 2 - 4 



• 3 • 



2 A 3 ) q 4 T 4 



< A o 



- 5Aj + 5 • 



4 A 2 - 5 



• 4 • 



3 A 3 ) q 5 T 5 



The response of the detector to radiation from a contaminated surface (I) is 

 dependent upon the intensity of the unscattered and scattered radiation (A's), 

 the attenuation of photons in the energy absorber (T) and the geometry effects 

 (q). Because sodium (Na 24 ) emits two photons 100 percent of the time, the 

 mathematics for calculating the detector response, after substitution of the 

 appropriate coefficients, has the following appearance: 



23 



