Evaluation of Delayed Neutron Data for JENDL-3.3

Yoshida, Tadashi; Okajima, Shigeaki; Sakurai, Takeshi; Nakajima, Kunihisa; Yamane, Tsuyoshi; Katakura, J.; Tahara, Yukihiro; Zukeran, Atsushi; Oyamatsu, Kazuhiro; Ohsawa, Takaaki; Nakagawa, Tsuneo; Tachibana, Takeshi

doi:10.1080/00223131.2002.10875059

Cited by 7 publications

(3 citation statements)

References 8 publications

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“…This behaviour is comparable to the one observed for 235 U, 238 U and 239 Pu neutron induced fission [11]. The decrease of the DN yields around 4 MeV is not yet well understood.…”

Section: Preliminary Resultssupporting

confidence: 59%

Delayed neutron measurements for²³²Th neutron-induced fission

Ledoux

Doré

Mosconi³

et al. 2010

EPJ Web of Conferences

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Abstract. Delayed neutrons (DN) play an important role in nuclear reactor physics. Innovative critical reactor studies bring to light the need of new DN yields data. For the Th fuel cycle, according to the OECD recommendation, DN of the 232 Th is needed with an accuracy of 5%. In the literature, significant discrepancies were observed for energies below 4 MeV and data are dispersed around 14 MeV. Therefore, a programme has been undertaken by CEA in order to measure DN yields from 232 Th with incident neutron energies from 2 to 16 MeV. In this paper, the experimental setup will be described and preliminary results obtained at the PTB Ion Accelerator Facility of Braunschweig for incident neutron beam energies of 2, 3, 4, 6, 7, 10 and 16 MeV will be presented. MotivationsDelayed neutrons (DN) emitted after fission are of prime interest for several topics. Among others, they allow the control of a nuclear reactor. With the development of reactors of new generation and/or new fuels, additional requirements appear in determining DN yields or to measure more accurately existing data. For the innovative thorium cycle, data on DN yields of 232 Th are needed. Unfortunately, available data in the literature are scarce and important discrepancies are observed as can be seen in Figure 1. Moreover, inside the recent ISTC project, results obtained between 3 and 5 MeV seem to indicate a quasi constant yield in this energy region which deviates from the energy dependence predicted by Yoshida et al. [1]. These observations have motivated physicists of CEA (Commissariatà l'énergie atomique et auxénergies alternatives) to undertake an experimental program for measurements of DN yields of 232 Th for the incident neutron energy range from 2 MeV up to 16 MeV.The experimental procedure, the neutron production facility and the detection setup will be described in the section 2. In section 3, analysis and simulations will be presented. Preliminary results will be shown in section 4. Experiment MethodologyEmission of delayed neutrons follows the beta decay of some fissions fragments called precursors. There are more than 200 different fragment isotopes involved which are usually lumped in 6 groups This is an Open Access article distributed under the terms of the Creative Commons Attribution-Noncommercial License 3.0, which permits unrestricted use, distribution, and reproduction in any noncommercial medium, provided the original work is properly cited.

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“…This behaviour is comparable to the one observed for 235 U, 238 U and 239 Pu neutron induced fission [11]. The decrease of the DN yields around 4 MeV is not yet well understood.…”

Section: Preliminary Resultssupporting

confidence: 59%

Delayed neutron measurements for²³²Th neutron-induced fission

Ledoux

Doré

Mosconi³

et al. 2010

EPJ Web of Conferences

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“…Since these fission fragments are highly excited, they de-excite by emitting several prompt neutrons and γ rays to reach their ground or metastable states within a time-scale of compound nucleus in the fission process. The independent fission product yield Y I (Z, A), which is a distribution of nuclides after emission of the prompt particles but before beta decay, plays an important role in many applications such as estimation of decay heat [2][3][4] and delayed neutron emission 5,6 in nuclear reactors, the reactor neutrino study 7 , prediction of fission product inventory at each stage of the nuclear fuel cycle, the radio-isotope production for medical applications, development of advanced reactor and transmutation systems, fission in the galactic chemical evolution 8 , and so on. A demand for high quality data of fission product yield (FPY) in such applications is rapidly increasing.…”

Section: Introductionmentioning

confidence: 99%

²³⁵U(n, f) Independent fission product yield and isomeric ratio calculated with the statistical Hauser–Feshbach theory

Okumura

Kawano

Jaffke

et al. 2018

Journal of Nuclear Science and Technology

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We have developed a Hauser-Feshbach fission fragment decay model, HF 3 D, which can be applied to the statistical decay of more than 500 primary fission fragment pairs (1,000 nuclides) produced by the neutron induced fission of 235 U. The fission fragment yield Y (A) and the total kinetic energy TKE are model inputs, and we estimate them from available experimental data for the 235 U(n th ,f) system. The model parameters in the statistical decay calculation are adjusted to reproduce some fission observables, such as the neutron emission multiplicity ν, its distribution P (ν), and the mass dependence ν(A).The calculated fission product yield and isomeric ratio are compared with experimental data. We show that the calculated independent fission product yield Y I (A) at the thermal energy reproduces the experimental data well, while the calculated isomeric ratios tend to be lower than the Madland-England model prediction. The model is extended to higher incident neutron energies up to the second chance fission threshold. We demonstrate for the first time that most of the isomeric ratios stay constant, although the production of isomeric state itself changes as the incident energy increases.

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“…Since the discovery of delayed neutron by Roberts et al shortly after the discovery of nuclear fission in 1939 [5], despite its tiny fraction, the delayed neutron has attracted people in various scientific communities, as its quite important role in keeping the thermal reactors critical, as well as the reactor systems containing high burn-up fuel, and transmutation of minor actinides. The delayed neutron yield has been measured [6][7][8][9] and repeatedly evaluated [1,[10][11][12] for various fissioning systems at several incident neutron energies. Some models for predicting the time-dependent delayed neutron yield have been proposed [13][14][15], and these studies pointed out the importance of fission yield data to perform these model calculations.…”

Section: Introductionmentioning

confidence: 99%

Energy Dependent Calculations of Fission Product, Prompt, and Delayed Neutron Yields for Neutron Induced Fission on $^{235}$U, $^{238}$U, and $^{239}$Pu

Okumura¹,

Kawano²,

Lovell³

et al. 2021

Preprint

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We perform energy dependent calculations of independent and cumulative fission product yields for 235 U, 238 U, and 239 Pu in the first chance fission region. Starting with the primary fission fragment distributions taken from available experimental data and analytical functions based on assumptions for the excitation energy and spin-parity distributions, the Hauser-Feshbach statistical decay treatment for fission fragment de-excitation is applied to more than 1,000 fission fragments for the incident neutron energies up to 5 MeV. The calculated independent fission product yields are then used as an input of β-decay to produce the cumulative yield, and summation calculations are performed. Model parameters in these procedures are adjusted by applying the Bayesian technique at the thermal energy for 235 U and 239 Pu and in the fast energy range for 238 U. The calculated fission observable quantities, such as the energy-dependent fission yields, and prompt and delayed neutron yields, are compared with available experimental data. We also study a possible impact of the second chance fission opening on the energy dependence of the delayed neutron yield by extrapolating the calculation.

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Evaluation of Delayed Neutron Data for JENDL-3.3

Cited by 7 publications

References 8 publications

Delayed neutron measurements for²³²Th neutron-induced fission

Delayed neutron measurements for²³²Th neutron-induced fission

²³⁵U(n, f) Independent fission product yield and isomeric ratio calculated with the statistical Hauser–Feshbach theory

Energy Dependent Calculations of Fission Product, Prompt, and Delayed Neutron Yields for Neutron Induced Fission on $^{235}$U, $^{238}$U, and $^{239}$Pu

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Evaluation of Delayed Neutron Data for JENDL-3.3

Cited by 7 publications

References 8 publications

Delayed neutron measurements for232Th neutron-induced fission

Delayed neutron measurements for232Th neutron-induced fission

235U(n, f) Independent fission product yield and isomeric ratio calculated with the statistical Hauser–Feshbach theory

Energy Dependent Calculations of Fission Product, Prompt, and Delayed Neutron Yields for Neutron Induced Fission on $^{235}$U, $^{238}$U, and $^{239}$Pu

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Delayed neutron measurements for²³²Th neutron-induced fission

Delayed neutron measurements for²³²Th neutron-induced fission

²³⁵U(n, f) Independent fission product yield and isomeric ratio calculated with the statistical Hauser–Feshbach theory