# LOW-FIDELITY CROSS SECTION COVARIANCES FOR 219 FISSION PRODUCTS IN THE FIRST NEUTRON REGION.

## Abstract

An extensive set of covariances for neutron cross sections in the energy range 5 keV-20 MeV has been developed to provide initial, low-fidelity but consistent uncertainty data for nuclear criticality safety applications. The methodology for the determination of such covariances combines the nuclear reaction model code EMPIRE, which calculates sensitivity to nuclear reaction model parameters, and the Bayesian code KALMAN to propagate uncertainty of the model parameters to cross sections. Taking into account the large scale of the project (219 fission products), only partial reference to experimental data has been made. Therefore, the covariances are, to a large extent, derived from the perturbation of several critical model parameters selected through the sensitivity analysis. These parameters define optical potential, level densities and pre-equilibrium emission. This work represents the first attempt ever to generate nuclear data covariances on such a scale.

- Authors:

- Publication Date:

- Research Org.:
- Brookhaven National Lab. (BNL), Upton, NY (United States)

- Sponsoring Org.:
- Doe - Office Of Science

- OSTI Identifier:
- 915433

- Report Number(s):
- BNL-79261-2007-IR

R&D Project: 05055; KB0301041; TRN: US0804982

- DOE Contract Number:
- DE-AC02-98CH10886

- Resource Type:
- Technical Report

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; CRITICALITY; CROSS SECTIONS; DATA COVARIANCES; ENERGY RANGE; FISSION; FISSION PRODUCTS; NEUTRONS; NUCLEAR REACTIONS; SAFETY; SENSITIVITY; SENSITIVITY ANALYSIS; COVARIANCE; UNCERTAINTY

### Citation Formats

```
PIGNI,M.T., HERMAN, M., OBLOZINSKY, P., and ROCHMAN, D.
```*LOW-FIDELITY CROSS SECTION COVARIANCES FOR 219 FISSION PRODUCTS IN THE FIRST NEUTRON REGION.*. United States: N. p., 2007.
Web. doi:10.2172/915433.

```
PIGNI,M.T., HERMAN, M., OBLOZINSKY, P., & ROCHMAN, D.
```*LOW-FIDELITY CROSS SECTION COVARIANCES FOR 219 FISSION PRODUCTS IN THE FIRST NEUTRON REGION.*. United States. doi:10.2172/915433.

```
PIGNI,M.T., HERMAN, M., OBLOZINSKY, P., and ROCHMAN, D. Fri .
"LOW-FIDELITY CROSS SECTION COVARIANCES FOR 219 FISSION PRODUCTS IN THE FIRST NEUTRON REGION.". United States.
doi:10.2172/915433. https://www.osti.gov/servlets/purl/915433.
```

```
@article{osti_915433,
```

title = {LOW-FIDELITY CROSS SECTION COVARIANCES FOR 219 FISSION PRODUCTS IN THE FIRST NEUTRON REGION.},

author = {PIGNI,M.T. and HERMAN, M. and OBLOZINSKY, P. and ROCHMAN, D.},

abstractNote = {An extensive set of covariances for neutron cross sections in the energy range 5 keV-20 MeV has been developed to provide initial, low-fidelity but consistent uncertainty data for nuclear criticality safety applications. The methodology for the determination of such covariances combines the nuclear reaction model code EMPIRE, which calculates sensitivity to nuclear reaction model parameters, and the Bayesian code KALMAN to propagate uncertainty of the model parameters to cross sections. Taking into account the large scale of the project (219 fission products), only partial reference to experimental data has been made. Therefore, the covariances are, to a large extent, derived from the perturbation of several critical model parameters selected through the sensitivity analysis. These parameters define optical potential, level densities and pre-equilibrium emission. This work represents the first attempt ever to generate nuclear data covariances on such a scale.},

doi = {10.2172/915433},

journal = {},

number = ,

volume = ,

place = {United States},

year = {Fri Apr 27 00:00:00 EDT 2007},

month = {Fri Apr 27 00:00:00 EDT 2007}

}