Production of important nuclides in spent nuclear fuel

SCK•CEN Mentor

Romojaro Pablo,, +32 (0)14 33 22 82

Expert group

Nuclear Systems Physics

SCK•CEN Co-mentor

Fiorito Luca , , +32 (0)14 33 21 86


Spent Nuclear Fuel (SNF) contains several thousand nuclides, concentration of which can be estimated using coupled neutron transport and fuel depletion calculations, based on nuclear data, operational history, geometry and material composition of fresh fuel. However, for cooling times in the range 1-1000 years, only up to 40 nuclides significantly contribute to the observables of interest for SNF: decay heat, neutron and gamma-ray emission, and reactivity. Additionally, power and burnup indicators are considered. These nuclides can be divided into 3 groups: actinides, fission products and activation products.

The list of important nuclides for a typical light water reactor will be obtained from literature. For each nuclide, its production path will be outlined, taking into account neutron induced fission, neutron capture and radioactive decay. Sensitivities of the production of each nuclide to all relevant nuclear data will be estimated, if possible, analytically. For more complex production chains, the sensitivity will be determined using random sampling codes, such as SANDY, and propagated with coupled neutron transport and fuel depletion codes, such as Serpent. For relevant nuclear data parameters, an overview of the current status of experimental and evaluated data will be given. Based on the sensitivities and current nuclear data uncertainties, a list of nuclear data requirements for improvements will be recommended.


  • The student will understand the physics models used to predict the SNF composition and the related observables
  • The student will familiarize him/herself with depletion codes such as Serpent
  • Sensitvities will be assessed analytically or numerically for all the nuclides in the spent fuel that play a role in SNF-related observables
  • The student will contributie to a scientific report with the findings of his/her work

The minimum diploma level of the candidate needs to be

Professional bachelor , Academic bachelor

The candidate needs to have a background in

Physics , Nuclear engineering