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The FIFRELIN Monte Carlo code has been upgraded recently by adding new capabilities, additional models and updated databases. Several examples are presented in this work as well as three different applications related to the prompt component in fission, gamma cascades from thermal neutron capture and the delayed component in fission associated to the time evolution of decay heat. [ABSTRACT FROM AUTHOR]

In this paper we present results from two recent studies, both related to the emission of prompt fission γ rays. Firstly, we have analyzed data from the reaction 235U(n, f) induced by fast neutrons of average energy E̅n E ̅ n = 1.7 MeV. The deduced spectral characteristics are an average multiplicity M̅γ M ̅ γ = 7.11 ± 0.44 γ rays per fission and an average total γ-ray energy release in fission E̅γ,tot E ̅ γ , tot = 5.51 ± 0.46 MeV, corresponding to an average γ-ray energy ɛ̅γ ɛ ̅ γ = 0.77 ± 0.08 MeV. Secondly, we have addressed – and answered – the question how those characteristics in general depend on the width of the chosen prompt time window and the timing resolution, determined by the employed detectors and electronics. The conclusion is that once this is known, it is possible to compare results from different experiments in a more meaningful way. [ABSTRACT FROM AUTHOR]

In a recent measurement of prompt γ rays from the spontaneous fission of 252Cf an experimental setup was chosen that allowed the study of angular correlations between γ rays and the nuclei from which they were emitted. The observed angular distribution of the prompt fission γ rays was then analyzed to estimate the relative contributions from radiation of different multipolarity. From that we hope to obtain more detailed information about the early stage of the de-excitation process of fission fragments, right after prompt neutron emission. First preliminary results are presented below. [ABSTRACT FROM AUTHOR]

In a recent measurement of prompt γ rays from the spontaneous fission of 252Cf an experimental setup was chosen that allowed the study of angular correlations between γ rays and the nuclei from which they were emitted. The observed angular distribution of prompt fission γ rays was then analyzed to estimate the relative contributions from radiation of different multipolarity. First preliminary results are presented and compared to previous angular correlation measurements from different fission processes and recent results from calculations with the Monte Carlo Hauser-Feshbach code FIFRELIN. [ABSTRACT FROM AUTHOR]

The investigation of prompt γ -ray emission in nuclear fission has a great relevance for the assessment of prompt heat generation in a reactor core and for the better understanding of the de-excitation mechanism of fission fragments. Some years ago experimental data was scarce and available only from a few fission reactions, 233,235U(nth, f), 239Pu(nth, f), and 252Cf(sf). Initiated by a high priority data request published by the OECD/NEA a dedicated prompt fission γ -ray measurement program is being conducted at the Joint Research Centre Geel. In recent years we obtained new and accurate prompt fission γ -ray spectrum (PFGS) characteristics (average number of photons per fission, average total energy per fission and mean photon energy) from 252Cf(sf), 235U(nth, f) and 239,241Pu(nth, f) within 2% of uncertainty. In order to understand the dependence of prompt fission γ -ray emission on the compound nuclear mass and excitation energy, we started a first measurement campaign on spontaneously fissioning plutonium and curium isotopes. Results on PFGS characteristics from 240,242Pu(sf) show a dependence on the fragment mass distribution rather than on the average prompt neutron multiplicity, pointing to a more complex competition between prompt fission γ -ray and neutron emission. [ABSTRACT FROM AUTHOR]

As a consequence of recent experimental results, previously established systematics for prompt fission γ -ray spectra (PFGS) characteristics as function of both atomic and mass number of the compound system have been revised. Although based on purely empirical dependences, it allows estimating average gamma-ray multiplicity, mean and total photon energy in cases, where the target nuclei are either not available or not accessible experimentally. Based on this systematics, we show in this paper that PFGS characteristics may also be predicted for fission induced by fast neutrons. Our calculations were performed for the target nuclei 238U, 235U and 239Pu in the neutron energy range from 0 to 20MeV, and the results are compared to existing experimental and theoretical values. [ABSTRACT FROM AUTHOR]

Benchmark reactor calculations have revealed an underestimation of γ -heat following fission of up to 28%. To improve the modelling of new nuclear reactors, the OECD/NEA initiated a nuclear data High Priority Request List (HPRL) entry for the major isotopes (235U, 239Pu). In response to that HPRL entry, we executed a dedicated measurement program on prompt fission γ -rays employing state-of-the-art lanthanum bromide (LaBr3) detectors with superior timing and good energy resolution. Our new results from 252Cf(sf), 235U(nth, f) and 241Pu(nth, f) provide prompt fission γ -ray spectra characteristics : average number of photons per fission, average total energy per fission and mean photon energy; all within 2% of uncertainty. We present preliminary results on 239Pu(nth, f), recently measured at the Budapest Neutron Centre and supported by the CHANDA Trans-national Access Activity, as well as discussing our different published results in comparison to the historical data and what it says about the discrepancy observed in the benchmark calculations. [ABSTRACT FROM AUTHOR]

For investigation of the basic characteristics of 14.1MeV neutron induced nuclear reactions on a number of important isotopes for nuclear science and engineering, a new experimental setup TANGRA has been constructed at the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research in Dubna. For testing its performance, the angular distribution of γ -rays (and neutrons) from the inelastic scattering of 14.1MeV neutrons on high-purity carbon was measured and the angular anisotropy of γ -rays from the reaction 12C(n, n' γ)12C was determined. This reaction is important from fundamental (differential cross-sections) and practical (non-destructive elemental analysis of materials containing carbon) point of view. The preliminary results for the anisotropy of the γ -ray emission from the inelastic scattering of 14.1-MeV neutrons on carbon are compared with already published literature data. A detailed data analysis for determining the correlations between inelastic scattered neutron and γ -ray emission will be published elsewhere. [ABSTRACT FROM AUTHOR]