CALCULATIONS OF THE TRANSPORT OF NEUTRONS AND SECONDARY GAMMA RAYS THROUGH CONCRETE FOR INCIDENT NEUTRONS IN THE ENERGY RANGE 15 TO 75 MeV.

Nuclear data relevant to shield design of FMIT facility

“…· 7 Li(d,n)!Be reaction with a Q value of 15 MeV could lead to neutrons with en~rgies·up to ~50· MeV. Transport calculations [4,5] ind.icated·that such neutrons would·severely impact shield design even if source s1;rengths were down·by two orders of magnitude from the peak around 14 MeV. · · .…”

“…Previous studies [5] have shown that gamma production cross sections for neutron energies above 20 MeV may be neglected in the design of bulk shields. Further confirmation of this is desirable.…”

“…This iteration did not include the water coolant of the drift tubes in the model of the geometry for the Monte Carlo calculation of neutron flux levels; An inclusion of the.water is expected to increase the tbermal: flux with ~ cor~esponding increase from low energ{ reaction modes .. Tlie 2.6 hour half-life r.adionuclide 56 Mn, from 5 Mn(n,y) 56 Mn, is expected to increase significantly with an appropriate treatment of the thermal flux. Table II.…”