Program - Brookhaven National Laboratory

Community’s 7th Framework Programme in the ANDES project under grant agreement No. 249671. It
has also been partially funded by the specific collaborative agreement between CIEMAT and UNED/UPM
in the area of ”High level waste transmutation”.
DE 3 4:20 PM
Measurement of Gamma Energy Distributions and Multiplicities Using STEFF
E. Murray, A. G. Smith, A. J. Pollitt
Department of Physics and Astronomy, University of Manchester, M13 9PL, Manchester, UK
J. Matarranz, I. Tsekhanovich
Université de Bordeaux/CENBG, 33175 Gradignan Cedex, France
T. Soldner, U. Koster
Insitut Laue-Langevin, 6 rue J. Horowitz, 38012 Grenoble, France
D.C Biswas
Bhabha Atomic Research Centre, Trombay, 400085, Mumbai, India
Prompt gamma ray energy distributions and multiplicities released during thermally induced fission of
235 U are measured using STEFF (SpecTrometer for Exotic Fission Fragments). Thermal neutrons are
provided by the high-flux reactor at the ILL, Grenoble. STEFF is a unique 2E2v device that uses a
coincidence timing method to measure the emission of prompt gamma rays as a function of the fragment
mass and energy. Following scission, the fission fragments contain excitation energy that is released via
prompt neutron and gamma ray emission as the fragment decays to its ground state. STEFF contains
an array of 11 NaI detectors around the uranium target providing a 6.8% photopeak detection efficiency
for acceptance of gamma rays released within 1ns of the scission time. STEFF also consists of 7 NE213
detectors, which detect the emission of prompt neutrons, the release of which is associated with reduction
of fragment energy and, to a lesser extent, fragment spin. Using STEFF, the gamma ray energies and
multiplicity have been measured as a function of mass, with a mass resolution of 4% and a gamma-ray
energy range up to 8 MeV. This experiment acts as a direct response to the NEA high priority demand
which requires more accurate knowledge of heating caused by gamma emission in the next generation of
nuclear reactors.
DE 4 4:40 PM
Gamma Heat Rate Evaluation for Material Irradiation Test in The Experimental Fast
Reactor Joyo
S. Maeda, H. Naito, T. Soga, C. Ito, T. Aoyama
Japan Atomic Energy Agency
One of the primary missions of the experimental fast reactor Joyo is to perform irradiation tests of fuel
and materials to support development of fast reactors. In a material irradiation test, it is essential to give
a precise characterization of the irradiation field, considering not only neutron fluence and displacements
per atom (dpa) but also temperature. The main heat source in a material irradiation test is the gamma
heating of surrounding materials, such as stainless steels constituting the irradiation rig including the
irradiation specimen and capsule. Accurate core and temperature calculation methods are required for
predicting the gamma heat rate and other key performance parameters for irradiation tests in Joyo. In
order to evaluate the gamma heating spatial distribution in fast reactors, it was needed to consider whole
components of gamma intensity. However, delayed gamma ray yield data of all actinides are not prepared
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