OCEANOGRAPHY AND FISHERIES 85 



of maximum permissible quantities of certain isotopes in sea water that might result from 

 releases from nuclear-powered ships(3) or from packaged wastes deposited in the coastal 

 waters of the Atlantic or Gulf of Mexico(2). 



Where there has been carefully controlled release of waste of known composition and 

 comprehensive monitoring of the radioactive materials that result in the water and in the 

 biological species important to man, many of the uncertainties inherent in complex extrapola- 

 tions can be eliminated. Permissible concentrations in the water and, in turn, appropriate 

 rates of release of radioactive wastes can be established with a high degree of confidence 

 directly from the observed concentrations in the species of interest. At this time, such ex- 

 perience is available from two large installations: one is the Windscale Works in England 

 which discharges fission-product type waste through a 3-kilometer long pipeline into the Irish 

 Sea, the other is the Hanford Operations in the United States which discharges reactor ef- 

 fluent containing neutron-activated materials into the Columbia River. 



The British state(7) that they originally considered the discharge of a few hundred 

 curies per month into the Irish Sea. They concluded from a preliminary investigation that a 

 discharge of about 100 c/day of beta activity and of about 0.1 c/day of alpha activity would 

 be completely safe. After experience was gained during the early years of operation through 

 careful monitoring of the shore, sea bed, and edible marine products, a reassessment 

 showed that discharges of nearly 1000 c/day of beta activity and of a few curies of alpha ac- 

 tivity would be safe provided the discharge of ruthenium-106 was restricted to 8,000 c/28 

 days and strontium-90 was restricted to 2,800 c/28 days. They suggest from more recent 

 work that it would be possible to discharge safely as much as 100,000 c/month. Their actual 

 mean discharge for the last ten months of 1957 is reported as 4,549 total beta c/28 days 

 (approximately 160 c/day). 



The effluent from the cooling system of the production reactors at Hanford is discharged 

 to the Columbia River after a single pass through the fuel channel. This discharge has been 

 monitored by extensive measurements of the river water, aquatic life, and other products 

 through which the radioactive materials might provide exposure to persons living in the en- 

 vironment of the plant(8). Such monitoring, maintained over a period of years, has per- 

 mitted correlations between the exposure reaching local inhabitants through a variety of path- 

 ways and the quantities of waste released. Management of the waste on the point-of-exposure 

 basis has thus been possible. 



During 1957, the neutron activation products released to the Columbia River were of 

 the order of 2000 c/day* in terms of gross beta emitters measured at Pasco, some 35 miles 

 downstream from the reactors and some 200 miles above the mouth of the river. A large part 

 of this activity originates from very short-lived isotopes which have significance in the exposure 

 received by persons who live near the Hanford plant and drink Columbia River water. This 

 quantity of activity is, of course, dispersed throughout a very large volume of river water and 

 thus the concentration in terms of microcuries per milliliter is well below the permissible 

 levels. These isotopes, with half-lives of a few days or less, are not of significance by the time 

 the river water reaches the ocean more than two weeks later. A few isotopes with longer half- 

 lives are present in significant amounts. The values listed in Geneva paper 743(8) would 

 indicate a daily discharge in the vicinity of Pasco of about 1000 c/day of Cr'\ and 15 c/day 

 each of P'' and Zn"'. Since there is a high concentration of P'' by biological processes, this is 



* Estimated from data published in Geneva Paper 743(8) and typical discharge rates for the Columbia River. 



