SEDL / STP / STP1046V2-EB / STP49448S

SANS and DENS Study of Irradiation Damage in a Reactor Pressure Vessel Material with a Systematic Variation of Irradiation Dose and Heat Treatments

Solt, Georges
Senior scientists, Paul Scherrer Institute, Villigen,

Frisius, Friedrich
Senior scientist, Research Center GKSS, Gcesthacht,

Waeber, Waldemar B.
Senior scientists, Paul Scherrer Institute, Villigen,

Bührer, Willi
Senior scientist, ETH Zurich, c/o PSI, Villigen,

Pages: 11    Published: Jan 1990

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Abstract

Defect clusters in a commercial RPV material, generated by a series of four controlled irradiations in a test reactor, and their thermal evolution with different heat treatments were investigated by SANS, and the studies were completed by independent DENS experiments performed with a triple-axis neutron spectrometer. The mean radius of the particles increases with the fluence and saturates, at the value of 7–9 Å, beyond the dose 1.5⋅1019n/cm2. From the ratio of their magnetic versus nuclear contrasts, the copper content of the particles was determined; for the volume fraction of the particles, one obtains 0.15 to 0.18% beyond the lowest dose 5×1018n/cm2. The irradiated-annealed-reirradiated samples show a scattering pattern indicating a bimodal size distribution, with an “aged” kind of particle with radii of 20 to 30 Å and a higher copper content than those described by the main peak near 7 to 9 Å. The DENS data confirm the SANS scattering curves at small (κ<0.3Å−1) momentum transfers, and add new information at the intermediate 0.3 to 0.6 Å⁻¹ range; this allows a more reliable determination of the size distribution. A short discussion of the correlated “inherent” variances for the parameters of the logarithmic-normal distribution, as determined from the neutron cross section, is given.