Yi Zuo

EXPERIMENTAL VERIFICATION OF HEAVY ION IRRADIATION SIMULATION

The heavy ion irradiation simulation of neutron and/or proton irradiation has been verified experimentally by the detailed study of radiation damage in α-Al2O3 irradiated at the equivalent dose by 5.28×1015cm-285 MeV19F ions and by 3×1020cm-2 En≥1MeV neutrons, respectively. The radiation damage created by irradiation was examined by a positron annihilation lifetime technique. The positron annihilation parameters of lifetime and intensity obtained for both irradiations in α-Al2O3 are all in good agreement. This demonstrates that the heavy ion irradiation can well simulate the neutron and/or proton irradiation.

Effect of triple ion beams on radiation damage in CLAM steel

The effect of triple ion beams has been investigated by simultaneous and sequential irradiations of gold, hydrogen and helium on radiation damage in the CLAM steel developed in China. The depth profile measurements of positron annihilation Doppler broadening S parameter were carried out as a function of slow-positron beam energy to examine the produced radiation damage. The experimental results show clearly the synergistic effect of displacement damage and hydrogen and helium on the formation of radiation damage. The synergistic effect of simultaneous triple ion beam irradiation of gold, hydrogen and helium ions was found to suppress the radiation damage in the CLAM steel due to the helium and/or hydrogen filling of vacancy clusters.

Synergistic Effect on Formation of Radiation Damage in CLAM Steel Studied by Triple Beam Irradiation

The synergistic effect associated with displacement damage, hydrogen and heliumin the China Low Activation Martensitic (CLAM) steel has been investigated using the triple ion beamirradiation. Triple ion beams, an iron beam of 109 MeV degraded by a tantalum foil of 7.45 μm thick, the100 keV hydrogen and 200 keV helium, were injected into the CLAM steel samples simultaneously or sequentially.The radiation damage examinations were carried out by the slow positron Doppler broadening technique. Themeasured S parameters indicate that the radiation damage is different for different irradiationprocedures with same dpa and concentrations of H and He. The sample suffers most severe damage in the simultaneoustriple beam irradiation. The present experimental results support the molecular dynamics simulation result that the H facilitates the He-bubble nucleation and growth.

Temperature Dependence of Radiation Damage in ODS Steel Studied by Triple Beam Irradiation and Positron Annihilation Techniques

The oxide dispersed strengthened (ODS) ferritic-martensitic steel was irradiated by 100MeV iron ion whose energy was degraded by using a Ta foil of 4 μm thick, 100 keV Hydrogen and 200 keV Helium at 480, 515, 550 and 580 °C. The irradiation fluences were 1×1016, 1.1×1015 and 6.8×1013/cm2, respectively for Fe, H and He. The techniques of positron annihilation lifetime and Doppler broadening of slow positron beam were utilized to examine the produced radiation damage. At 550 °C the maximal positron annihilation lifetime and S parameter of Doppler broadening were observed, implyin g tha t 550 °C is the pea k temperature of swelling. The S parameter and annihilation lifetime of the sample irradiated at 515 °C by the single Fe ion beam were smaller compared to the triple beam irradiation at the same temperature, implying that the triple beam irradiation caused more severe damage than the single beam irradiation.

Irradiation Hardening and Indentation Size Effect of the 304NG Stainless Steels After Triple Beam Irradiation

The nuclear grade 304NG stainless steel (SS) has been developed in the past several decades as the new generation of internal material in light water reactors. The irradiation effects of domestic 304NG SS were simulated by the triple ion beam irradiation on the heavy ion, hydrogen and helium triple ion beam irradiation platform at China institute of Atomic Energy. The irradiation experiments were carried out with various doses (6, 15, 30 and 150 dpa at 300 ℃) and temperatures (300, 350, 400, 450 ℃ with 6 dpa). The depth-dependent hardness and elastic modulus of the specimens before and after irradiation were measured by nanoindentation with the continuous stiffness measurement technique. For the specimens irradiated at 300 ℃, the hardness generally increases with the increasing dose. The depth-dependent hardness in the micro-indentation region (indentation depth h > 100 nm) of those specimens with dose less than 30 dpa can be well explained by Nix & Gao formulae of the indentation size effect. For the specimens irradiated at different temperatures, the hardening effect can be observed for all specimens for indentation depth beyond 1 μm and the hardness decreases with increasing irradiation temperature. However, as the irradiation temperature elevates or the dose increases up to 150 dpa, the hardness for the indentation depth h < 500 nm deviates significantly from the projection of the Nix & Gao model. The surface morphology observed by SEM and the S parameters extracted from the slow positron annihilation Doppler broadening indicate that the drastic reduction of hardness those specimens with indentation depth h < 500 nm can be attributed to the change of surface morphology.

Electromagnetic Moments of Proton-Rich {sup 28}P and Decomposition of Its Spin

The magnetic moment of 28P(Iπ = 3+, T1/2 = 270.3 ms) has been measured precisely by means of β‐NMR technique. The obtained magnetic moment is |μ(28P)| = 0.3115 (34) μN. Combined with the magnetic moment of its mirror partner 28Al, the nuclear spin I = 3 is decomposed into its 4 components. The measurement of the Q moment has also been tried. From the preliminary NQR spectrum, it was found that the quadrupole coupling constant eqQ/h may be slightly larger than the prediction, which may show enhancement of the Q moment.