辐射防护 ›› 2020, Vol. 40 ›› Issue (6): 491-495.

• 辐射传输与屏蔽 • 上一篇    下一篇

Measurement of niobium reaction rate formaterial surveillance tests in fast reactors

Chikara Ito1,2, Shigetaka Maeda2, Toshihiko Inoue1, Hideki Tomita3, Tetsuo Iguchi3   

  • 出版日期:2020-11-20 发布日期:2021-01-27

Measurement of niobium reaction rate formaterial surveillance tests in fast reactors

Chikara Ito1,2, Shigetaka Maeda2, Toshihiko Inoue1, Hideki Tomita3, Tetsuo Iguchi3   

  1. 1. Fuels and Materials Department,Japan Atomic Energy Agency,Oarai,Ibaraki 311-1393,Japan;
    2. Experimental Fast Reactor Department,Japan Atomic Energy Agency,Oarai,Ibaraki 311-1393,Japan;
    3. Department of Energy Engineering,Nagoya University,Nagoya 464-8603,Japan
  • Online:2020-11-20 Published:2021-01-27
  • Contact: Chikara Ito E-mail:ito.chikara@jaea.go.jp
  • About author:The presenting author is in the employ of the Japan Atomic Energy Agency (JAEA). He has been engaged in research and development of the dosimetry and instrumentation for fast reactors at the Experimental Fast Reactor Joyo in the Oarai Research and Development Institute of JAEA. After the accident at the Fukushima Daiichi Nuclear Power Station, he was also engaged in research and development for environmental recovery and the decommissioning of nuclear power plants. Currently, he is engaged in research on fuels and materials for fast reactors and development of post-irradiation examination technology at the hot laboratories for the post-irradiation examination in Joyo.

Abstract: A highly accurate and precise technique for measurement of the 93Nb(n,n’)93mNb reaction rate was established for the material surveillance tests,etc.in fast reactors.The self-absorption effect on the measurement of the characteristic X-rays emitted by 93mNb was decreased by the dissolution and evaporation to dryness of niobium dosimeter.A highly precise count of the number of 93Nb atoms was obtained by measuring the niobium solution concentration using inductively coupled plasma mass spectrometry.X-rays of 93mNb were measured accurately by means of comparing the X-ray intensity of irradiated niobium solution with that of the solution in which stable 93Nb was added.The difference between both intensities indicates the effect of 182Ta,which is generated from an impurity tantalum,and the intensity of X-rays from 93mNb was evaluated.Measurement error of the 93Nb(n,n’)93mNb reaction rate was reduced to be less than 4%,which was equivalent to the other reaction rate errors of dosimeters used for Joyo dosimetry.In addition,an advanced technique using Resonance Ionization Mass Spectrometry was proposed for the precise measurement of 93mNb yield,and 93mNb will be resonance-ionized selectively by discriminating the hyperfine splitting of the atomic energy levels between 93Nb and 93mNb at high resolution.

Key words: Isord-10, niobium, reaction rate, material surveillance test, fast reactor, characteristic x-rays, experimental fast reactor joyo, resonance ionization mass spectrometry, hyperfine structure