Abstract
To evaluate the feasibility of development of nuclear transmutation technology and an advanced nuclear system, precise nuclear data of neutron capture cross sections for long-lived fission products (LLFPs) and minor actinides (MAs) are indispensable. In this chapter, we present our research activities for the measurements of neutron capture cross sections for LLFPs and MAs.
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Keywords
- Activation method
- ANNRI
- J-PARC
- Long-lived fission products
- Minor actinides
- Neutron capture cross section
- Time-of-flight method
1 Introduction
Associated with the social acceptability of nuclear power reactors, it is desirable to solve the problems of nuclear waste management of the long-lived fission products (LLFPs) and minor actinides (MAs) existing in spent nuclear fuels. A method of nuclear transmutation seems to be one of the solutions to reduce the radiotoxicity of nuclear wastes. The transmutation method makes it possible to reduce both the size of a repository for packages of nuclear wastes and the storage risks for the long term. To evaluate the feasibility of development of the nuclear transmutation method, precise nuclear data of neutron capture cross sections for LLFPs and MAs are indispensable.
This chapter presents joint research activities by JAEA and universities for measurements of the neutron capture cross sections for LLFPs and MAs by activation and neutron time-of-flight (TOF) methods.
2 Present Situation of Data for LLFPs and MAs
Although accurate data of neutron capture cross sections are necessary to evaluate reaction rates and burn-up times, there are discrepancies among the reported data for the thermal neutron capture cross sections for LLFPs and MAs. As an example of MA, Fig. 5.1 shows the trend of the thermal neutron capture cross section data for 237Np: the discrepancies are about 10 %. Discrepancies between experimental and evaluated data still remain. As for LLFPs, e.g., 93Zr, Fig. 5.2 shows that there are discrepancies between ENDF/B-VII.0 and JENDL-4.0 evaluations in the region of the thermal neutron energy. Thus, our concern was focused to remeasure the neutron capture cross sections of those LLFPs and MAs.
3 Measurement Activities by the Activation Method
Neutron capture cross sections were determined on the basis of Westcott’s convention [1] by an activation method. The results for LLFPs [2–23] are listed in Table 5.1, and for MAs [24–31] in Table 5.2, together with previously reported data. Here, the symbols σeff, σ0, and I 0 denote the effective cross section, the thermal neutron capture cross section, and the resonance integral, respectively; σ0 is the cross section at the neutron energy of 25.3 meV.
Nuclear waste sometimes contains a large amount of stable nuclei having the same atomic number as that of long-lived fission products. These stable nuclei absorb thermal neutrons during the neutron irradiation of the nuclear waste and affect the neutron economics; the reaction rate of the target nuclei is reduced. Moreover, some of these stable nuclei breed more radioactive nuclei by the neutron capture process. It is also necessary for transmutation study to accurately estimate these influences caused by stable nuclei involved in the FP targets. The cross sections of the stable nuclei, such as 127I [14] and 133Cs [20], were also measured; the results are shown in Table 5.1.
As seen in Table 5.1, the thermal cross section for 137Cs is about twice as large as the previous data reported by Stupegia [2]. As for 90Sr, its thermal cross section is found to be much smaller than the data reported by Zeisel [6]. As seen in Table 5.2, the cross section of 238Np is obtained for the first time. Thus, the joint research activities of the Japan Atomic Energy Agency (JAEA) and universities have measured the cross sections for important LLFPs and MAs by the activation method.
4 Measurement Activities at J-PARC/MLF/ANNRI
A new experimental apparatus called the accurate neutron nucleus reaction measurement instrument (ANNRI) has been constructed on the beam line no. 4 (BL04) of the MLF in the J-PARC. The ANNRI has two detector systems. One of them is a large Ge detector array, which consists of two cluster-Ge detectors, eight coaxial-shaped Ge detectors, and BGO Compton suppression detectors; the other is a large NaI(Tl) spectrometer (Fig. 5.3). The ANNRI has an advantage for neutron cross-section measurements because the MLF facility can provide the strongest neutron intensity in the world.
The neutron capture cross sections of 237Np [32, 33], 241Am [34], 244Cm [35], 93Zr [36], 99Tc [37], and 107Pd [38] have been measured relative to the 10B(n, αγ) standard cross section by the TOF method. Some highlights of results obtained in our research activities are shown in Fig. 5.4 for 237Np and in Fig. 5.5 for 93Zr. The results obtained at the ANNRI are good agreement with the data reported by Weston (Fig. 5.4). The 93Zr cross sections in Fig. 5.5 present results greatly different from the evaluated data in the thermal neutron energy region. One finds that the present results support the value of the thermal cross section reported in 2007 [39].
5 Summary
This chapter described the JAEA research activities for the measurement of neutron capture cross sections for LLFPs and MAs by activation and neutron time-of-flight (TOF) methods. We summarized our results of the thermal neutron capture cross section and the resonance integral for some of the important LLFPs and MAs by the activation method.
Operation of a new experimental apparatus called the accurate neutron nucleus reaction measurement instrument (ANNRI) in the MLF at J-PARC has been started for neutron capture cross-section measurements of MAs and LLFPs. Some of the highlights of our results have been shown here.
References
Westcott CH et al (1958) Proceedings of 2nd International Conference on Peaceful Uses of Atomic Energy, Geneva, vol 16, United Nations, New York, p. 70
Stupegia DC (1960) J Nucl Energ A12:16
Harada H et al (1990) J Nucl Sci Technol 27(6):577
Sekine T et al (1993) J Nucl Sci Technol 30(11):1099
Wada H et al (2000) J Nucl Sci Technol 37(10):827
Zeisel G (1966) Acta Phys Austr 23:5223
Harada H et al (1994) J Nucl Sci Technol 31(3):173
Nakamura S et al (2001) J Nucl Sci Technol 38(12):1029
Lucas M et al (1977) IAEA-TC-119/14, p 407–432
Harada H et al (1995) J Nucl Sci Technol 32(5):395
Eastwood TA et al (1958) Proceedings of 2nd International Conference on Peaceful Uses of Atomic Energy, Geneva, vol 16. United Nations, New York, p 54
Nakamura S et al (1996) J Nucl Sci Technol 33(4):283
Friedmann L et al (1983) Radiochim Acta 33:182
Nakamura S et al (1999) J Nucl Sci Technol 36(3):223
Baerg AP et al (1958) Can J Phys 36:863
Katoh T et al (1997) J Nucl Sci Technol 34(5):431
Bayly JG et al (1958) Inorg Nucl Chem 5:259
Katoh T et al (1999) J Nucl Sci Technol 36(8):635
Baerg AP et al (1960) Can J Chem 38:2528
Nakamura S et al (1999) J Nucl Sci Technol 36(10):847
Masyanov SM et al (1993) Atom Energ 73:673
Harada H et al (2000) J Nucl Sci Technol 37(9):821
Katoh T et al (2002) J Nucl Sci Technol 39(7):705
Kobayashi K et al (1994) J Nucl Sci Technol 31(12):1239
Katoh T et al (2003) J Nucl Sci Technol 40(8):559
Harada H et al (2006) J Nucl Sci Technol 43(11):1289
Harada H et al (2004) J Nucl Sci Technol 41(1):1
Shinohara N et al (1997) J Nucl Sci Technol 34(7):613
Nakamura S et al (2007) J Nucl Sci Technol 44(12):1500
Ice CH (1966) Du Pont: Savannah River reports, vol 66, p 69
Ohta M et al (2006) J Nucl Sci Technol 43(12):1441
Hirose K et al. (2014) Nuclear Data Sheets 119:48–51
Hirose K et al (2013) J Nucl Sci Technol 50:188–200
Harada H et al (2014) Nuclear Data Sheets 119:61–64
Kimura A et al (2012) J Nucl Sci Technol 49:708–724
Hori J et al (2011) J Korean Phys Soc 59(2):1777–1780
Kino K et al (2014) Nuclear Data Sheets 119:140–142
Nakamura S et al (2014) Nuclear Data Sheets 119:143–146
Nakamura S et al (2007) J Nucl Sci Technol 44(1):21
Acknowledgments
The authors thank the staff at Kyoto University Reactor Institute, Rikkyo University Reactor and JRR-3M. A part of this work has been carried out under the Visiting Researcher’s Program of the Research Reactor Institute, Kyoto University. Moreover, the authors appreciate the accelerator staff of J-PARC for their operation of the accelerator.
This work is supported by JSPS KAKENHI (22226016).
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Nakamura, S. et al. (2015). Precise Measurements of Neutron Capture Cross Sections for LLFPs and MAs. In: Nakajima, K. (eds) Nuclear Back-end and Transmutation Technology for Waste Disposal. Springer, Tokyo. https://doi.org/10.1007/978-4-431-55111-9_5
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