Numerical Simulation Of Radioactive Sand Transport And Block Technology

With nuclear technology development, environmental pollution problems caused byradioactive waste have become an increasing concern. To evaluate the radiological nuclideimpact on the environment, the liberation of radionuclide migration in the environment shallbe known firstly. In the arid and semi arid region of Gobi, gale and windy weather conditionswill cause the ground is migrated and diffused by radioactive sand resulted in polluting thesurrounding environment.In order to prevent the pollution area expanded, necessarymeasures should be taken to stop the interception. To find reasonable block measures, weneed to understand the migration of radioactive sand, and to evaluate the effect of blockingmeasures. By exacting field sampling and making analysis, we find that the radio nuclidesform in fallout or radionuclide compound with sand, and the radionuclide concentration areclosely related by grain size. Therefore, sand will be made as the radionuclide vector in thisarticle, first get sand migration, combined relationship between radionuclide concentrationand size relations, finally get the regularities of radionuclide migration.Sand transport model is built by fluent soft; the basic law of sand transport is roughly inaccord with wind tunnel experimental data, which proves that the model is correct. Combinewith sediment-transport rate concept in wind sand flow, the nuclide transport rate is defined tocharacterize radionuclide transport. For stop measures, reference sand prevention and controlmeasures, windbreak is selected to block radioactive sand by comparison material,transportation, cost and service life etc. The windbreak is built with the local soil, gravel andsand, which has the advantages of low cost, easy local materials, long service life and no needfor long-term maintenance. The principle of windbreak sand-fixation is theoretically analyzedand wind-break wall is added in sand transport model, after that the wind sand resistance,prevent radionuclide performance under different conditions are analyzed, then theperformance of the method is assessed. The wind velocity, wind wall height and slopeparameters are also changed to determine the effect of wind-break wall block. The resultsshowed that radionuclide137Cs transport rate is vertical distribution of the overall decreasedexponentially, forms transmission rate peak in close proximity to the ground. Radionuclide137Cs transport rate vertical variation trend is same under different wind velocity, the difference is that the rate of delivery becomes bigger in overall and altitude in delivery ratepeak is increases by wind velocity. Wind deceleration rate, sand and radionuclide blockingrate are used to evaluate windbreak effect. At the same windbreak, wind deceleration rate isthe same under different wind velocity, but sand and radionuclide blocking rate are decreasewith wind velocity increasing. Under same wind velocity, wind deceleration effect is the sameas the different height of windbreak, while the higher windbreak is, the better sand andradionuclide blocking effect is. The windbreak block effect is better with windward slopeincreasing, while is invariable with leeward slope. So in actual construction process, weshould try to improve the wall height and make the windward side of the steep slope, so as toachieve the best block effects; considering the size of projects and windbreak structurestability,45°leeward slope will be used.