Employing FREYA for fission product yield evaluations

The fast event-by-event fission code FREYA (Fission Reaction Event Yield Algorithm) generates large samples of complete fission events while employing only a few physics-based parameters. Not only is FREYA fast, it is also flexible, able to employ a variety of input formats to test the implications of various fission yield evaluations on neutron and photon observables. We describe how FREYA was applied to the neutron-rich nuclei needed for r-process nucleosynthesis calculations as an example of this flexibility. Finally, we discuss how we plan to make use of this flexibility to extend FREYA to calculations of cumulative fission product yields to aid evaluations of these yields in the future.

Download Full-text

New Fission Product Yield Measurements at Oregon State University

EPJ Web of Conferences ◽

10.1051/epjconf/202024201010 ◽

2020 ◽

Vol 242 ◽

pp. 01010

Author(s):

Aaron Tamashiro ◽

Jason Burke ◽

Stephen Padgett ◽

Sean Burcher ◽

Todd Palmer ◽

...

Keyword(s):

Fission Product ◽

Branching Ratio ◽

Nuclear Research ◽

Product Yield ◽

State University ◽

Product Yields ◽

Fission Product Yields ◽

Training Research ◽

Γ Rays ◽

Oregon State University

Cumulative fast fission product yields for 235 U and 238 U were measured at Godiva-IV in burst mode. Data was collected starting 45 minutes after the prompt irradiation. Data analysis codes were developed to analyze gammarays and calculate fission product yields with their respective uncertainties. Due to uncertainties in the branching ratios, different γ-rays from the same isotope led to different fission yield. This led to an effort at Oregon State University (OSU) to utilize the Rabbit facility at their 1 MegaWatt Training, Research, Isotopes, General Atomics (TRIGA) nuclear research reactor. The new experimental setup will allow us to measure branching ratio data and short-lived fission product yields starting seconds after a prompt irradiation.

Download Full-text

Measurements of short-lived fission product yields using monoenergetic neutron and photon beams

EPJ Web of Conferences ◽

10.1051/epjconf/202024201004 ◽

2020 ◽

Vol 242 ◽

pp. 01004

Author(s):

Sean Finch ◽

Matthew Gooden ◽

Chris Hagmann ◽

Calvin Howell ◽

Vanessa Linero ◽

...

Keyword(s):

Fission Product ◽

Fission Products ◽

Product Yield ◽

Transfer System ◽

Photon Beams ◽

Product Yields ◽

Transit Times ◽

Hpge Detectors ◽

Fission Product Yields ◽

Pu Isotopes

A joint TUNL-LLNL-LANL collaboration was formed to measure the absolute fission product yields from the 235 U, 238 U, and 239 Pu isotopes. Our goal is to study the energy evolution of fission products using monoenergetic beams. In order to extend our successful fission product-yield studies to include products with shorter half-lives, a RApid Belt-driven Irradiated Target Transfer System, named RABITTS, was constructed. This system allows us to perform cyclic activation and quantify fission products with γ-ray spectroscopy using HPGe detectors. Both a 1 meter and 10 meter transfer system have been developed, with transit times of 0.4 and 1.1 seconds, respectively. Using these systems, we have measured sub-second half-lives. Our goal is to measure fission product yields from neutron-induced fission with En = 0.5 − 14.8 MeV and photofission with Eγ = 8 − 15 MeV. A detailed characterization of the system’s performance is presented, including preliminary fission product measurements, and the expected sensitivity.

Download Full-text

FISSION YIELD UNCERTAINTY PROPAGATION IN MULTI-PASS REFUELING PEBBLE-BED HTGR

EPJ Web of Conferences ◽

10.1051/epjconf/202124715006 ◽

2021 ◽

Vol 247 ◽

pp. 15006

Author(s):

Yizhen Wang ◽

Menglei Cui ◽

Jiong Guo ◽

Fu Li

Keyword(s):

Fission Product ◽

Sampling Method ◽

Uncertainty Propagation ◽

Product Yield ◽

Nuclear Data ◽

Fission Yield ◽

Pebble Bed ◽

Stochastic Sampling ◽

Fission Product Yield ◽

Burnup Calculation

Multi-pass refueling scheme is a highlighted feature of pebble bed HTGR which spatially mixes the burnup calculation inside core. Such refueling scheme relate burnup calculation in one region of the core to others and thus affects the uncertainty propagation of nuclear data, e.g. fission product yield. In this work, thermal neutron induced U-235 fission product yield uncertainties are propagated in HTR-PM models with various refueling schemes in V.S.O.P. code. And the effect of multi-pass refueling scheme is studied. Bayesian method is applied to estimate the covariance of fission product yield based on ENDF/B-VII.1 fission yield sub-library. Uncertainty quantification is performed with stochastic sampling method and log-normal based correlated sampling method is used to generate reasonable and self-consistent fission product yield samples. The analyzed results indicate that multi-pass refueling scheme could affect the uncertainty propagation of reactor local responses.

Download Full-text

Completeness of experimental fission product yields in EXFOR database

EPJ Web of Conferences ◽

10.1051/epjconf/202023905013 ◽

2020 ◽

Vol 239 ◽

pp. 05013

Author(s):

Takanari Fukuda ◽

Shin Okumura ◽

Naohiko Otuka

Keyword(s):

Fission Product ◽

Nuclear Reaction ◽

Product Yield ◽

Yield Data ◽

Product Yields ◽

Wide Range ◽

Fission Product Yields ◽

Reaction Data ◽

Data Centres ◽

Exfor Database

The Nuclear Reaction Data Centres (NRDC) collaborate on worldwide compilation and dissemination of experimental nuclear reaction data by developing and maintaining the EXFOR database. With the growing interests in the fission product yields of various projectiles and a wide range of energies, several evaluation activities are ongoing. In line with these activities, the IAEA conducted completeness check of fission product yield data in EXFOR against two experimental datasets developed by the ENDF and UKFY library evaluators. The present status and statistics of these datasets as well as the result of the EXFOR completeness review are presented.

Download Full-text