The application of nano silica extracted from kaolinite, bentonite and rice straw is proposed as treatment material for the purification of primary coolant water of pressurized water reactors. Three elements were used to simulate some radionuclides that can be released in the primary coolant water namely, strontium, nickel and cobalt. Various batch experiments were performed including selection of efficient sorption nanomaterial, optimum operational weight ratio (element/nano material), selectivity of the nano silica for elements used, determination of the equilibrium curve of sorption process, and desorption behavior of nanomaterial with pH and temperature variation. The samples were analyzed using the inductively coupled plasma emission spectrometer. Silica of kaolinite, bentonite and rice straw showed the same results in the efficiency/ capability removing the three elements used. Silica form of rice straw has been selected as nano-treated materials for economic and environmental reasons. The sorption process reached equilibrium after 30 min approximately. The experiments demonstrated that the sorption reaction of elements by the nano-silica is an irreversible reaction with the change of temperature and pH. The obtained results indicated that using the nano silica increased the safety margin of the treatment stage in the multi barrier concept.

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The first Egyptian (ET-RR1) research reactor has been in operation since 1961 at the Egyptian Atomic Energy Authority (EAEA) Inshas site. Therefore, at present, it faces a serious problem due to aging equipment, especially those directly in contact with the environment such as the underground settling tanks of nuclear and radioactive waste. The possible leakage of radionuclides from these aging tanks and their migration to the aquifer was studied using instantaneous release.This study was done based on the geological and hydrological characteristics of the site, which were obtained from the hydrogeological data of 25 wells previously drilled at the site of the reactor[1]. These data were used to calculate the trend of water levels, hydraulic gradient, and formulation of water table maps from 1993–2002. This information was utilized to determine water velocity in the unsaturated zone.Radionuclides released from the settling tank to the aquifer were screened according to the radionuclides that have high migration ability and high activity. The amount of fission and activation products of the burned fuels that contaminated the water content of the reactor pool were considered as 10% of the original spent fuel. The radionuclides considered in this case were H-3, Sr-90, Zr-93, Tc-99, Cd-113, Cs-135, Cs-137, Sm-151, Pu-238, Pu-240, Pu-241, and Am-241.The instantaneous release was analyzed by theoretical calculations, taking into consideration the migration mechanism of the various radionuclides through the soil space between the tank bottom and the aquifer. The migration mechanism through the unsaturated zone was considered depending on soil type, thickness of the unsaturated zone, water velocity, and other factors that are specific for each radionuclide, namely retardation factor, which is the function of the specific distribution coefficient of each radionuclide. This was considered collectively as delay time. Meanwhile, the mechanism of radionuclide migration during their passage in the water body of the aquifer was the main focus of this study.The degree of water pollution in the aquifer at a point of contact with the main water body of Ismailia Canal 1000 m from the reactor site was assessed for the instantaneous release by comparing the results obtained with the regulations of the standard limit of radionuclides in drinking water[2,3].

The present study focused on the retention capability of the different local backfill materials and on horizontal and vertical radionuclide migration in simulated repository conditions of a saturated static humid environment, using single or combined components of the near-field. The results obtained from semi-field experiment show that no migration of cesium radionuclide was detected outside the backfill zone within the time interval of the experiment. This reflects the possible efficiency, of the backfill materials used, for the confinement of radioactivity to the disposal site. On the other hand laboratory experiments show the effect of simulated repository condition on the sorption and desorption properties of backfill materials. It is clear from the results obtained that the presence of cement waste forms in equilibrium with underground water affect the retention capability of the backfill materials. The motivation of the work was a desire to provide a basis for minimizing radioactive waste processing by improving nonradioactive engineering barriers.