Development of a reference database for beta-delayed neutron emission

Dimitriou, P.*; Dillmann, I.*; Singh, B.*; Piksaikin, V.*; Rykaczewski, K. P.*; Tain, J. L.*; Algora, A.*; Banerjee, K.*; Borzov, I. N.*; Cano-Ott, D.*; et al.

Nuclear Data Sheets, 173, p.144 - 238, 2021/03

https://doi.org/10.1016/j.nds.2021.04.006

-delayed neutron emission has been of interest since the discovery of nuclear fission. In nuclear power reactors, delayed-neutron data play a crucial role in reactor kinetics calculations and safe operation. -delayed neutron data also have a significant impact in the field of nuclear structure and astrophysics especially as nuclei farther away from stability are explored at the new generation of radioactive beam facilities. Several compilations of -decay half-lives and delayed-neutron emission probabilities are available, however, complete documentation of measurements and evaluation procedures is often missing for these properties. Efforts to address this gap in nuclear data and create an updated compilation and evaluation of -delayed neutron properties were undertaken under the auspices of the International Atomic Energy Agency (IAEA) which formed a Coordinated Research Project (CRP) on "Development of a Reference Database of Beta-delayed Neutron Emission Data". In this paper we summarize the work that was performed and present the results of the CRP.

IRDFF-II; A New neutron metrology library

Trkov, A.*; Griffin, P. J.*; Simakov, S. P.*; Greenwood, L. R.*; Zolotarev, K. I.*; Capote, R.*; Aldama, D. L.*; Chechev, V.*; Destouches, C.*; Kahler, A. C.*; et al.

Nuclear Data Sheets, 163, p.1 - 108, 2020/01

https://doi.org/10.1016/j.nds.2019.12.001

The version II of the International Reactor Dosimetry and Fusion File (IRDFF-II) has been released as a consistent set of nuclear data for fission and fusion neutron metrology applications up to 60 MeV neutron energy. The library is intended to support: (a) applications in research reactors; (b) safety and regulatory applications in the nuclear power generation in commercial fission reactors; and c) material damage studies in support of the research and development of advanced fusion concepts. The paper describes the contents of the library, documents the thorough verification process used in its preparation, and provides an extensive set of validation data gathered from a wide range of neutron benchmark fields. The new library is expected to become the international reference in neutron metrology for multiple applications.

CIELO collaboration summary results; International evaluations of neutron reactions on uranium, plutonium, iron, oxygen and hydrogen

Chadwick, M. B.*; Capote, R.*; Trkov, A.*; Herman, M. W.*; Brown, D. A.*; Hale, G. M.*; Kahler, A. C.*; Talou, P.*; Plompen, A. J.*; Schillebeeckx, P.*; et al.

Nuclear Data Sheets, 148, p.189 - 213, 2018/02

https://doi.org/10.1016/j.nds.2018.02.003

The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear facilities - U, U, Pu, Fe, O and H - with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality. This report summarizes our results and outlines plans for the next phase of this collaboration.

Covariance of neutron cross sections for O through R-matrix analysis

Kunieda, Satoshi; Kawano, Toshihiko*; Paris, M.*; Hale, G. M.*; Shibata, Keiichi; Fukahori, Tokio

Nuclear Data Sheets, 123, p.159 - 164, 2015/01

https://doi.org/10.1016/j.nds.2014.12.028

The collision matrix in the R-matrix theory is unitary, hence theory brings strong constraints to behavior of the parameters. An unitarity-imposed R-matrix analysis is carried out for O system to evaluate O neutron cross-sections in the resolved resonance range. Covariance matrices are also estimated both for the cross-sections and angular distributions with a deterministic method. Present results mirror the nature in the theory as well as experimental information.

New approach for nuclear reaction model in the combination of intra-nuclear cascade and DWBA

Hashimoto, Shintaro; Iwamoto, Osamu; Iwamoto, Yosuke; Sato, Tatsuhiko; Niita, Koji*

Nuclear Data Sheets, 118, p.258 - 261, 2014/05

https://doi.org/10.1016/j.nds.2014.04.052

Particle transport simulation codes based on the Monte Carlo technique are utilized to predict interaction of radiations with materials. The codes describe the transport of all particles, e.g. photons, electrons, nucleons, and heavy ions by various models for physical processes and nuclear reaction. In particular, nuclear reaction processes are essential parts for the accurate prediction. Recently, accelerator-based neutron sources using proton or deuteron beams with energies from 10 to 100 MeV come to be utilized for scientific and medical applications. For neutron source design, accurate description of neutron yields created by nuclear reactions is required in the simulation. However, the Intra-Nuclear Cascade type models used in most of the simulation codes are not enough to reproduce experimental data because of neglecting quantum mechanical effects. In this study, we combined the cascade type models and an event generator using the DWBA (Distorted Wave Born Approximation) calculation, which is a theoretical model based on quantum mechanics. We verified that the calculated results with the combination model can reproduce experimental data of neutron spectra in deuteron-induced reactions. We will also present the validity of the combination model for proton-induced reactions.

Measurements of neutron capture cross sections of Sn and Sn with J-PARC/MLF/ANNRI

Kimura, Atsushi; Hirose, Kentaro; Nakamura, Shoji; Harada, Hideo; Hara, Kaoru; Hori, Junichi*; Igashira, Masayuki*; Kamiyama, Takashi*; Katabuchi, Tatsuya*; Kino, Koichi*; et al.

Nuclear Data Sheets, 119, p.150 - 153, 2014/05

https://doi.org/10.1016/j.nds.2014.08.042

Surrogate reactions research at JAEA/Tokyo Tech

Chiba, Satoshi; Nishio, Katsuhisa; Makii, Hiroyuki; Aritomo, Yoshihiro*; Nishinaka, Ichiro; Ishii, Tetsuro; Tsukada, Kazuaki; Asai, Masato; Furutaka, Kazuyoshi; Hashimoto, Shintaro; et al.

Nuclear Data Sheets, 119, p.229 - 232, 2014/05

https://doi.org/10.1016/j.nds.2014.08.063

Measurements of capture rays from the neutron resonances of Se and Se at the J-PARC/MLF/ANNRI

Hori, Junichi*; Yashima, Hiroshi*; Nakamura, Shoji; Furutaka, Kazuyoshi; Hara, Kaoru; Harada, Hideo; Hirose, Kentaro; Kimura, Atsushi; Kitatani, Fumito; Koizumi, Mitsuo; et al.

Nuclear Data Sheets, 119, p.128 - 131, 2014/05

https://doi.org/10.1016/j.nds.2014.08.036

In this work, we measured the capture rays from the neutron resonances of Se and Se. A neutron time-of-flight method was adopted for the measurements with a 4 Ge spectrometer installed at the Accurate Neutron-Nucleus Reaction measurement Instrument (ANNRI) in the J-PARC Material and Life science experimental Facility (MLF). The -ray pulse-height spectra corresponding to the 27-eV resonance of Se and the 113-, 212-, 291-, 342-, 690- and 864-eV resonances of Se were obtained by gating on the TOF regions, respectively. The relative intensities of those primary transitions were derived and compared with the previous experimental data. For the 27-eV resonance of Se, a strong primary transition to the 293-keV state was observed. As for Se, the quite differences of the decay pattern were found between the resonances.

Development of anti-Compton LaBr(Ce) spectrometer for measurement of surrogate reactions

Makii, Hiroyuki; Ota, Shuya*; Ishii, Tetsuro; Nishio, Katsuhisa; Nishinaka, Ichiro; Furutaka, Kazuyoshi; Wakabayashi, Yasuo*; Chiba, Satoshi*; Igashira, Masayuki*

Nuclear Data Sheets, 119, p.361 - 364, 2014/05

https://doi.org/10.1016/j.nds.2014.08.099

Anti-Compton LaBr(Ce) spectrometers have been installed at JAEA-Tokai tandem accelerator facility in order to measure the rays from the highly excited states produced by surrogate reactions. Each spectrometer consists of a central LaBr(Ce) detector with a diameter of 10.2 cm and a length of 12.7 cm, and an annular BGO detector with a thickness of 2.5 cm and a length of 25.4 cm. In this contribution, we will present the results of performance test using the standard ray source and high-energy rays from the Al(p,)Si reaction, and a measurement plan for (n,) cross sections using a surrogate reaction at JAEA-Tokai tandem accelerator facility.

Analysis of Pu isotopes in melted fuel by neutron resonance transmission; Examination by linear absorption model

Kitatani, Fumito; Harada, Hideo; Takamine, Jun; Kureta, Masatoshi; Seya, Michio

Nuclear Data Sheets, 118, p.505 - 509, 2014/04

https://doi.org/10.1016/j.nds.2014.04.119

Feasibility study of neutron resonance transmission analysis (NRTA) has been started to quantify nuclear materials in particle-like debris of melted fuel formed in severe accidents of nuclear reactor such as Fukushima Daiichi Nuclear Power Plants. The achievable measurement accuracy was examined by NRTA using a linear absorption model for the sample in which substances other than nuclear fuel materials, such as boron, were contained. In this study, boron and iron were considered to be contained in spent nuclear fuel as impurities. The neutron flight path is 5 m, that is the length between the neutron source and a neutron detector. Neutron absorption spectra were calculated using the total neutron absorption cross-section by JENDL-4.0. The absorption spectra together with their errors were evaluated. The achievable accuracy of Pu isotopic density was deduced as a function of neutron intensity and impurity density. This research was supported by JSGO/MEXT.