90 



peak radioactivity level is seen in the early 1960's, coincident with 

 a cessation of the atmospheric testing of nuclear weapons. Levels 

 fall off after this point, continuing to fall to the present day with 

 the exception of a small signal from the Chernobyl accident. 



Research surveys further upriver have supported the Russian re- 

 ports that radioactivity is measured above background levels only 

 when one gets within a few hundred kilometers of the nuclear fa- 

 cilities. Surveys of the Anadyr River, the closest major Russian Si- 

 berian river to Alaska, have shown a very clean, nearly pristine en- 

 vironment. Now, those sites that we talked about, the dump sites, 

 the holding sites, the processing plants are not in that river sys- 

 tem. It is only at very localized sites in the Kara Sea region that 

 elevated radionuclide concentrations are identified. 



The major conclusion from the program sampling so far is that 

 the largest signals for regionwide radionuclide contamination in 

 the Arctic marine environment appear to arise from atmospheric 

 testing of nuclear weapons, nuclear fuel reprocessing wastes from 

 facilities in Western Europe and accidents such as Chernobyl, in 

 that order. 



This program is not restricted to in situ sampling but has also 

 developed a suite of very sophisticated models to analyze transport 

 of radionuclides throughout the Arctic basin. The core of this suite 

 is the Navy's operational polar ice prediction model, which has 

 been adapted to address contaminant transport questions. It is im- 

 portant to note that this is a physics-based model requiring the lat- 

 est supercomputing resources to operate. 



Now, I have a presentation, both a poster of one piece of the out- 

 put, but I have right here next to me, if we can turn the lights, 

 Dr. Ruth Preller from the Naval Research Laboratory who is in 

 charge of this model, and I have a video which should show the 

 model running over a 10-year period. 



[A video tape was played.] 



Admiral Pelaez. I think it is important to note that in that sim- 

 ulation, Mr. Chairman, it has some conservatism in it. It assumed 

 a constant rate of discharge out of these rivers, but it did not give 

 any consideration for settling that might occur, so we assumed full 

 transport and mixing to be the case there, which does become more 

 conservative. I cannot say it is the worst case because it was a con- 

 stant introduction over a 10-year period. 



But that is the sort of thing that we have the capability of pre- 

 dicting very accurately and being able to look at various situations 

 of potential contaminants entering those three river systems. We 

 have similar models that will show, for instance, contamination en- 

 tering at other points. 



^^^lile the physical processes which affect contaminant transport 

 may vary from one contaminant to the next, it should be noted that 

 this model, as well as the other models developed, are robust 

 enough. They can show that transport throughout the basin. There- 

 fore, the tremendous investment I believe that has been made in 

 this has far-reaching applications, much beyond the specific man- 

 date of this program. 



At this time, radionuclide concentrations in Alaskan waters re- 

 main at background levels, and I am talking about the manmade 

 radionuclides. Indeed, human radiation dosage from naturally oc- 



I 



