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Abstract
A conceptual neutronic design of the cold-neutron source (CNS) for the Egyptian second research reactor (ETRR-2) was done using the MCNP code. Parametric analysis to choose the type and geometry of the moderator, and the required CNS dimensions to maximize the cold neutron production, was performed. The moderator cell would have spherical annulus structure containing liquid hydrogen. The cold neutron gain and cold neutron brightness are calculated together with the nuclear heat load of the CNS. Analyses of the estimated performance of the CNS have been done regarding the effect of void fraction in the moderator cell together with the ortho: para ratios.
A calculation line was developed to minimize the errors resulting from calculating isotopes inventory. This was achieved by using a combination of burn-up calculation codes and the MCNP code. A surface source was created surrounding the tangential tube this source was used in the neutronic conceptual design of the CNS. To verify the calculation methodology, the calculations are compared with the experimental results at every stage of calculation.
The spherical annulus moderator cell with liquid hydrogen layer thickness of 75 cm was selected to give the maximum gain factor. The calculation of brightness at the entrance of the cold neutron guide gives reasonable results compared with other facilities that use liquid hydrogen as a moderator.
Parametric analysis has been done to estimate the effects of the ortho: para ratio and void fraction. The result shows that the worst case occur in the neutron wavelength from 0.2 to 1.2 nm at state of 100% para and 40% void fraction. The brightness’ at this state decreases by 12.13%. The heat load calculations in the moderator cell gives heat load to be 95.48 W. The results show that ETRR-2 CNS facility performance is competent with other CNS facilities in other reactors that use the liquid hydrogen as a moderator.