Excitation functions were measured for the
180
W
(
n
,
2
n
)
179mW,
182
W
(
n
,
p
)
182Ta,
182
W
(
n
,
p
)
182m2Ta,
182
W
(
n
,
α
)
179m2Hf,
183
W
(
n
,
p
)
183Ta,
183
W
(
n
,
α
)
180mHf,
184
W
(
n
,
...p
)
184Ta,
184
W
(
n
,
α
)
181Hf,
186
W
(
n
,
p
)
186Ta,
186
W
(
n
,
α
)
183Hf,
186
W
(
n
,
n
′
α
)
182mHf, and
186
W
(
n
,
2
n
)
185W reactions from 13.4 to 14.9 MeV. The data of these reactions that are dominant for neutron-induced activation in tungsten were in most cases either defective or incomplete. The experimental results are compared with the results of calculations including all activation channels for the stable W isotopes up to a neutron incident energy of 20 MeV, using two global- and one local-parameter approaches which take into account direct reaction, pre-equilibrium emission (PE), and compound nucleus contributions. The sensitivity of the calculated cross sections to various model approaches and parameters is derived and discussed also in connection with the deviation from unity of calculated-to-experimental activity ratios from benchmark experiments with natural W irradiated by D–T fusion neutrons. The particular importance of the charged-particle emission in this atomic-mass range for PE model validation is discussed and the need for additional data for incident energies above 15 MeV is demonstrated.
Two experiments were carried out and analysed in order to test tools used for the nuclear design of fusion devices. Neutron and photon flux spectra were measured in a thick tungsten assembly during ...irradiation with D-T neutrons. They were analysed with the Monte Carlo transport code MCNP-4C using nuclear data of the libraries FENDL-2, EFF-2.4 and JENDL-3.3. Small pieces of tungsten were irradiated with D-T neutrons, and the neutron-induced activities measured after the irradiation, were analysed with the inventory code FISPACT using data of the libraries EAF-2003 and FENDL/A-2. Deviations of experimental from calculated results show that an improvement of the tungsten data base is required. Tungsten is widely proposed for use in plasma facing components of future fusion devices.
Samples of lanthanum, tantalum and erbium which are constituents of structural materials and insulating coatings for blankets of fusion reactor designs have been irradiated in a fusion peak neutron ...field. The induced gamma activities were measured and the results were used to validate calculations with the European activation system EASY-2005. Good agreement for the prediction of major contributors to the contact dose rate of the materials was found, but for minor contributors the calculation deviated up to 50%.
Yttrium is an element in oxide dispersion strengthened (ODS) steels to be used as structural material at high neutron doses and temperatures. Lead acts as a neutron multiplier and coolant in breeding ...blanket concepts such as the EU test blanket modules (TBM) with Pb–17Li. Samples of pure Y and Pb were irradiated with D–T fusion neutrons. The radioactivity following irradiation was determined several times during decay by γ-spectroscopy. The results were analysed with the European Activation System. Ratios of calculated-to-experimental values for individual activities are discussed in connection with the expected activation performance of the materials in fusion power plant conditions.
Tungsten is the preferred material for the divertor plates of fusion devices and a constituent of reduced activation structural materials. Samples of pure tungsten were irradiated with D-T fusion ...neutrons. The radioactivity following irradiation was determined several times during decay by γ-spectroscopy. The results were analysed with the European Activation System. Ratios of calculated-to-experimental values for individual activities are discussed in connection with the expected activation performance of the material on fusion power plant conditions.
CuCrZr is used in high heat flux components of ITER and other fusion reactor designs. A CuCrZr alloy of the European Fusion Technology Programme was irradiated with D–T neutrons, and the γ-activities ...of all nuclides which are relevant up to the recycling limit of the material were measured. The results were analysed with the European Activation System (versions EASY-2001 and EASY-2003). The calculated total activation property of the material was validated within 10%. The long-term radioactivity was estimated to be well below the hands-on limit with an uncertainty of 19%.
Pulse radiolysis studies have been used to investigate the early phenomena in the radiolysis of acrylic acid, methyl acrylate, butyl vinyl ether, propionic acid, methyl acetate and butyl ether; the ...latter three solvents were used as model compounds for these vinyl monomers. The triplet state, radical cation, radical anion, and free radical of pyrene (cyclohexadienyl type) were observed to various degrees in the radiolysis of pyrene in these monomers. In acrylic acid, where the free radical and the cation dominate, the monomer polymerizes efficiently, whereas in butyl vinyl ether, where the anion dominates, polymerization does not occur. The behavior of methyl acrylate lies between that of acrylic acid and butyl vinyl ether. However, the high intensity of the electron pulses creates a high concentration of radicals leading to a short lifetime of the radical which in turn leads to a much smaller yield of polymerization. The mechanism of polymerization under high energy radiation is found to be free radical in nature.
