Activation analysis for the reference low-activation vanadium alloy NIFS-HEAT-2

• Main Authors: Teruya Tanaka, Takuya Nagasaka, Takeo Muroga, Masanori Yamazaki, Takeshi Toyama
• Format: Article
• Language: English
• Published: Elsevier 2020-12-01
• Series: Nuclear Materials and Energy
• Subjects: Vanadium alloy; NIFS-HEAT-2; Activation analysis; Impurity; Gamma-ray
• Online Access: http://www.sciencedirect.com/science/article/pii/S2352179120300582

Activation analysis of impurities was performed on a test specimen of the reference low-activation vanadium alloy NIFS-HEAT-2 (V-4Cr-4Ti) which has been irradiated in Japan Materials Testing Reactor (JMTR) ~16 years before. Since the radioactive nuclides from V, Cr and Ti are produced with short half-lives, intense peaks of 60Co (T1/2 = 5.27 years) were dominant in the measured gamma-ray energy spectra and peaks of 94Nb (2.03 × 104 years) were also observed. The concentrations were evaluated to be 0.41 wppm and 0.71 wppm respectively from comparison with results of radioactivity calculation using the FISPACT-2005 code. In the analysis, detection of 108mAg (418 years), which would have a considerable influence on the material recycling after the usage in a fusion reactor, was intense motivation. Although the peaks of 108mAg has not been detected, the concentration of Ag was estimated to be <0.034 wppm from analysis of detection limit in gamma-ray peak count. Gamma-ray peaks originated from other impurity elements were not observed in the spectra, and the present analysis are supporting the superior low activation properties of NIFS-HEAT-2.