الفهرس 
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Abstract
ABSTARCT
The neutronic calculations play an important role in the safe and efficient operation and utilization of the research reactors For HTRR-2. more elaborate neutromc calculations than those which were done in the design stage have been carried out to achieve the safety and follow-up of the reactor operation and utilization In addition, the validity of the adopted l.7.TRR-2 neutromc calculational line is presented through a comparison between the measured and the calculated neutromc parameters of the different core configurations starting from the initial cores of the commissioning stage till the current operating one. The following work has been carried out to improve the ETRR-2 neutronic calculational line -
Many different neutron cross sections (XSs) libraries are created to form a database as an operational verified reference to cover the entire reactor operational states. So, XSs libraries are created at 50 kW, 400 k\V, 1 MW, 2.2 MW, 5MW, 7MW, 10MW, 15MW and 22MW to take into account the effect of changing the fuel and coolant temperatures, the coolant density, the Xenon saturation levels, operating regimes, etc.
An analytical study of different fuel element models is performed to choose the most accurate one to be applied for neutronic calculations
Each fuel element in the reactor core has now its own nuclear data instead of having an average nuclear data for each type of fuel elements as was done during the design and commissioning stage. This is not necessary only for burn-up calculations but for fuel management calculations as well The neutron cross sections data of the fuel elements calculated at different values
r-4 of burn-up are also improved due to decreasing the burn-up interval between each
two burn-up calculational steps. Moreover, the fuel element cell calculations are carried out in 12 energy groups instead of 5 groups as was applied before. The cell models of the control plate zone are corrected and inserted in the libraries to be used in the calculations.
The fuel burn-up calculations are carried out following the historical operating records to consider not only the variation of the reactor power and control plate patterns but also the sequence of control plate movement during the reactor operation which has an important effect on such calculations.