Comparison of material irradiation conditions for fusion, spallation, stripping and fission neutron sources

IFMIF: overview of the validation activities

“…In turn, spallation sources present a neutron spectrum with long tails reaching the hundreds MeV range transmutation efficiency, especially for the lighter elements which have a high potential in deteriorating mechanical properties. A comparison of IFMIF with other available neutron sources has been performed [5], where it is explained how the spectrum that IFMIF provides, reproduces accurately fusion reactors spectrum with a flattop near the 14 MeV peak and at intermediate energies, while the closest available spallation sources, ESS and XADS, are one order of magnitude lower in flux in these critical range of energies. IFMIF, presently in its Engineering Validation and Engineering Design Activities phase (IFMIF/EVEDA), started in 2007 under the framework of the Broader Approach (BA) Agreement between EURATOM and Japan, is entering into conclusive stages [6].…”

Estimation of Induced Activity in an ADSS Facility

“…But the neutron yield, most often, will be higher at 2 GeV which has prompted other workers to study this energy range for characterization of ADSS parameters. It has also been mentioned earlier in this section that target stability and other studies can be carried out at a much lower energy [3]. Moreover, spallation reaction starts to predominate at proton energy of around 300 MeV.…”

“…Since the codes do not distinguish between formation in the ground or metastable state, in the case of such radionuclides, we have considered the half-life of the ground state unless the metastable state is much longer lived than the ground state. Figure 1 shows the activity build-up of 3 H, 14 C, 22, 24 Na, 45 Ca and 60 Co. 3 H, 45 Ca and 60 Co are nuclides of concern for radiotoxicity of the environment while 14 C and 22 Na are biologically important. It has been observed that for 400 MeV incident proton energy the activity build-up for 30 days of irradiation is in the range of 10 10 to 2x10 11 Bq for all the species except for 14 C. Maximum activity of the order of 2.3x10 11 Bq is produced for 45 Ca.…”

“…210 Po activity, which is a potential source of α-contamination, is generated to the extent of ~ 8 -9 x10 6 MBq. 3 H, which poses radiation hazard threat to the environment by adding to ground water contamination, is produced with an activity of 10 5 MBq from the irradiation of T91 and D9 beam windows. Proper containment for both 3 H and 210 Po should be ensured to protect plant personnel and environment from unwanted exposure to radiation while operating a target assembly containing a beam window.…”

“…It has been found that the neutron economy is optimized around 1 GeV proton energy [1,2]. However, various structural parameters, target stability, heat generation profile and other logistics are studied at much lower beam energies [3], which are easily available. Running a high energy machine at high currents would lead to the generation of considerable amount of radioactive waste depending on the target-projectile combination.…”