2001 Fiscal Year Final Research Report Summary
DEVELOPMENT OF ONE DIMENSIONAL ANGULAR CORRELATION OF POSITRON ANNIHILATION RADIATION MEASU REING WIDE MOMENTUM REGION FOR NON-DESTRUCTIVE INSPECTION OF NUCLEAR REACTOR PRESSURE VESSEL
| Project/Area Number |
12358005
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Nuclear engineering
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
HASEGAWA Masayuki TOHOKU UNIVERSITY, INSTITUTE FOR MATERIALS RESEARCH, PROFESSOR, 金属材料研究所, 教授 (80005975)
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| Co-Investigator(Kenkyū-buntansha) |
YUBUTA Kunio TOHOKU UNIVERSITY, INSTITUTE FOR MATERIALS RESEARCH, RESEARCH ASSOCIATE, 金属材料研究所, 助手 (00302208)
TANG Zeng TOHOKU UNIVERSITY, INSTITUTE FOR MATERIALS RESEARCH, RESEARCH ASSOCIATE, 金属材料研究所, 助手 (80271972)
NAGAI Yasuyoshi TOHOKU UNIVERSITY, INSTITUTE FOR MATERIALS RESEARCH, ASSOCIATE PROFESSOR, 金属材料研究所, 助教授 (10302209)
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| Project Period (FY) |
2000 – 2001
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| Keywords | POSITRON ANNIHILATION / LIFE MANAGEMENT OF NUCLEAR POWER REACTOR / WIDE RANGE MOMENTUM DISTRIBUTION MEASUREMENT / POSITION SENSITIVE GAMMA-RAY DETECTOR |
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| Research Abstract |
Ensuring safe operation of nuclear power reactors is a recent urgent issue since the reactors of the first generation are going over their initially designed operating lifetimes. One of the most important problem is the embrittlement of the reactor pressure vessel (RPV) steels by neutron irradiation, which is considered to be caused by the ultrafine precipitation of Cu impurities contained in the RPV steels (〜O.3 %) of the first generation induced by neutron irradiation. However, little is known about the irradiation-induced Cu precipitates or aggregations because it is very difficult to observe them even by current high-resolution transmission electron microscopes (HR-TEM). The aim of this work is to develop a new type of one-dimensional angular correlation of positron annihilation radiation (1D-ACAR) apparatus for non-destructive inspection of the RPV steels. Our final goal is to establish the method, using the apparatus, to analyze the formation process and the structure of the ultr
… More
afine Cu precipitates, difficult to detect by other techniques, utilizing affinity-induced positron confinement in the Cu precipitate which we have recently found.
For the above purpose, we have to develop a new 1D-ACAR apparatus which enables us to measure the momentum distribution of not only conduction electrons but also core electrons with high momentum resolution (〜1x10^<-3>mc). Thus, we developed a pair of position sensitive gamma-ray detectors with high position resolution (〜2 mm), high counting rate (wide effective area : 150 mm x 150 mm) and high time resolution. One detector was mounted on a fixed support, and the other detector was mounted on a support movable vertically. In the next step, the sample chamber for low temperature (〜15K) measurements and the support for the chamber were constructed. Finally, the electric system for the coincidence measurement of a pair of positron annihilation gamma-rays was set up.
We performed a test measurement of the new 1D-ACAR apparatus for the evaluation of the performance. A long tail in the high momentum region was observed, which results in high background and poor position resolution. We found that this was caused by the reflection of the scintillation photons at the light-guide surfaces. To remove this effect, the detectors are now improving the setting of the light-guide geometry and the amplifiers for the timing outputs. Less
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