Measurements of Tritium and¹⁴C Production Cross Sections for 14.7-MeV Neutrons on¹⁷O and¹⁸O

A first generation deuterium-tritium (D-T) fusion reactor such as the International Thermonuclear Experimental Reactor has the nominal fusion power of 1,000 MW, which corresponds to a total output of {approximately} 3 {times} 10{sup 20} 14-MeV n/s. In contemporary designs of these fusion reactors, high-purity light water (H{sub 2}O) is potentially used as a coolant. Hence, the cooling water is subject to 14-MeV neutron irradiation. The predominant neutron energies are above the thresholds for many reactions that are not normally significant in fission reactor analysis. Therefore, consideration of water activation with 14-MeV neutrons is important from the viewpoint of fusion reactor safety and waste management of long-lived isotopes such as {sup 14}C and tritium. Here, samples of water isotopically enriched in {sup 17}O, {sup 18}O, and {sup 2}H along with natural water were bombarded by neutrons from the intense deuterium-tritium source provided by the Fusion Neutron Source facility. After irradiation, the accumulated concentrations of {sup 3}H and {sup 14}C activities were determined by the liquid scintillation method. Special attention was paid to {sup 14}C losses in the gas phase during irradiation and preparation of scintillation counting samples. Cross sections for the {sup 17}O(n,{alpha}){sup 14}C, {sup 18}O(n,n{prime}{alpha}){sup 14}C, {sup 17}O(n,t){sup 15}N, andmore » {sup 18}O(n,t){sup 16}N reactions at 14.7 MeV have been measured for the first time. The following values have been obtained for these reactions: 18 {+-} 3.3, 35.4 {+-} 6.5, 0.82 {+-} 0.15, and 26.8 {+-} 4.9 mb, respectively, relative to the {sup 93}Nb(n,2n){sup 92m}Nb standard reaction cross section of 460 mb. A study of the systematics of (n,t) reactions at 14.7 MeV on light nuclei (atomic number Z < 10) has been carried out. The experimental cross-section values are also compared with data in the comprehensive activation libraries.« less