Radioactive waste materials release ionized rays and if the rays penetrate in environment, they cause serious pollution. The goal of this research project  is to study processing  the liquid, solid and gas waste materials by using sedimentation, evaporation, ionic exchange and absorption on suitable absorbers methods. Sternidium 90 and Cesium 137 are also among  nucleotide which are obtained  in the process of fission of Uranium 235 or plutonium 239 nucleotide. Stransium is very much similar to calcium and if it enters into human body as a contamination, it takes the place of calcium and by  radiating Beta ray, dialysis   entire water in the human body and change it into hydrogen and oxygenated water, both known as a poisonous composition for human being. Cesium  137 is another  problematic radionuclide  with 30.1 years half-life and 6.02  output (sedimentation) in the course of nuclear fission  in  controlled form in a  nuclear reactor and in uncontrolled form in nuclear explosions- in   tragic nuclear incidences such as Chernobyl in Russia and Harrisburg in United States. Cesium migrates into environment as suspended particles. With respect to the half-life of this radionuclide, the environment stays contaminated for four hundred years.

 

Iraj Bayat, Ph.D. Faculty Member, Retired from Iran Atomic Energy Organization

Seyed Hossein Omidiani, Ph.D., Associate member of Physics Association and Solar Energy  Association of Iranerif";}

 

Radioactive waste materials release ionized rays and if the rays penetrate in environment, they cause serious pollution. The goal of this research project  is to study processing  the liquid, solid and gas waste materials by using sedimentation, evaporation, ionic exchange and absorption on suitable absorbers methods. Sternidium 90 and Cesium 137 are also among  nucleotide which are obtained  in the process of fission of Uranium 235 or plutonium 239 nucleotide. Stransium is very much similar to calcium and if it enters into human body as a contamination, it takes the place of calcium and by  radiating Beta ray, dialysis   entire water in the human body and change it into hydrogen and oxygenated water, both known as a poisonous composition for human being. Cesium  137 is another  problematic radionuclide  with 30.1 years half-life and 6.02  output (sedimentation) in the course of nuclear fission  in  controlled form in a  nuclear reactor and in uncontrolled form in nuclear explosions- in   tragic nuclear incidences such as Chernobyl in Russia and Harrisburg in United States. Cesium migrates into environment as suspended particles. With respect to the half-life of this radionuclide, the environment stays contaminated for four hundred years.

 

Research Method:

The nuclear waste installations should  ensure a permanent and overall control and supervision on radioactive  waste. Because of their large  volume, liquid wastes  should be disposed  by chemical sedimentation and ionic exchange methods, at the same time. After  isolation of radio-nucleotides from liquid waste, if the liquid waste shows no sign of radioactivity; that is, if it is free from radioactive, it could be discharged in environment. The remaining radio-nucleotides  obtained from sedimentation process should be mixed in cement and stored in 200 and 400 Ltr. Barrels. Care must be taken so these barrels would not radiate more than 15 mg Beta or Gamma rays to 1 meter distance. In most nuclear research centers, mineral exchanger resins such as ammonium molybdenum phosphate is used to isolate cesium. The mentioned resin has high preventive power. The tests, which have been already carried out show, that one kilogram AMP is strong enough to prevent 62 grams cesium. As it is known,  one gram cesium as 83 Curie activity; therefore, to take the environment healthy,  strict measures should be taken to prevent arrival of  this problematic element  which- as mentioned before- is developed in reactors with high output- into human environment. Furthermore, it must be ensured that the amount of radio-nucleotide entering into environment would  not exceed the amount of radioactivity standard as suggested by International Atomic Energy Agency.

In addition, food products, particularly milk,  should be also controlled and studied for the detection of any of the aforesaid elements since cesium penetrates into plant through roots and arrives into foodstuff cycle by plants. Cesium can not penetrate in soil more than 4 centimeters since it is an electropositive element with high affinity. Pollution control factor should be taken as a criteria to disposal  radioactive wastes. As the pollution removal factor is higher, it shows the disposal has been carried out more efficiently.  The research method in this paper has highest factor in contamination control.

 

Discussion and Conclusion:

Different methods are used to dispose radioactive wastes. Ionic exchange method consists of  cations, anion and chelae procedures are significantly  suitable. Ionic exchange method is a very good substitute  if the co-charged anions and cations ions complex developers are not available in the solution. As an example, for reactor water contamination, keeping fuel bars causes deposit of some radio-nucleotide inside water ad if disturbing ions are in the solution, chemical  sedimentation will be used.

It is possible to isolate all radio-nucleotides from wastes that make sediments when exposed to liquid. Some of these radio-nucleotides, such as zinc and aluminum, which are solved in additional caustic solvent and are amphhoteric electrolytes could not be isolated in sedimentation method; therefore, both sedimentation and ionic exchange should be used for their isolation, simultaneously. By mixing both methods, the radioactive wastes could be efficiently isolated form liquid waste.

Some Alfa developing elements such as plutonium 239 with 24000 years half-life can easily threaten human environment. In order to isolate these radio-nucleotides, chemical methods, liquid extract from liquid and ionic exchange should be used and the results should be kept stable in the phosphates, borosilicate and ceramic glasses to prevent any penetration in environment; for, these types of glasses are highly resistance against heat, radiation and mechanical factors. By employing these methods, it is possible to prevent environment pollution and contamination to radioactive materials.

 

References:

1.      International Atomic Energy Agency, "Radioactive Waste Management Glossary" Second Edition, IAEA- TECDOC-44", Vienna (1998).

2.      Karlen, G. Johnson, K.J. Bergstroem, R. "Seasonal Variation in the Activity Concentration of Cs 137 in Swedish Roe-deer and their Daily Intake" Vol. 58, J. Environ, Radioact. 14 (1991) 91-103.

3.      International Atomic Energy Agency, "Handling, Conditioning and Disposal of Spent Sealed Sources" IAEA- TECDOC-548, Vienna (1990).

4.      Bulletin, Quarterly Journal of the International Atomic Energy, Vol. 40, No. 30, 1998, Vienna, Austria

5.      5. Nair, S. "A Sensitivity Study of Ingestion Population, Dose Following a Hypothetical Atmospheric Release from a Unclear Poser Station" The transfer of Radioactive Materials in the Terrestrial Environment Subsequent to an Accidental Release to Atmosphere (Proc. Sem. Dublin, 1983), Commission  of the  European Communities, Luxemburg (1983).

6.      International  Atomic Energy Agency, Sea Disposal of Radioactive Waste, IAEA- TECDOC-588, IAEA, Vienna, 1991.