14-MeV neutron multiplication measurement in lead

The experimentally measured value of 14-MeV neutron multiplication for 10-cm thick lead in rectangular geometry agrees within 1% of the corresponding calculated value using the MORSE-E code with the Los Alamos National Laboratory 30-group cross-section set CLAW-IV, in P/sub 3/ scattering approximation. This result is in direct contrast with measurements with lead spheres of 3-, 6-, 9-, and 12-cm radii, where the measured multiplication values are found to be --15% higher than the corresponding transport calculations performed using the ANISN and NITRAN codes with the ENDF/B-IV library. However, Monte Carlo calculations using the MORSE-E code with the CLAW- IV library, as well as those using the MCNP code with the ENDF/B-V library, agree very well. Thus, the real difference of leakage neutron multiplication in lead is not between the measurements and the calculations. It is found that by using lead as a neutron multiplier in practical fusion blankets, a 5 to 10% higher neutron multiplication can be obtained than with beryllium for identical configurations of the multiplier