**1. NAME AND TITLE**

SENSIT: One-Dimensional, Multigroup Cross Section and Design Sensitivity and Uncertainty
Analysis Code System Generalized Perturbation Theory.

**2. CONTRIBUTOR**

Los Alamos National Laboratory, Los Alamos, New Mexico.

**3. CODING LANGUAGE AND COMPUTER**

Fortran, Assembler language; CDC 7600.

**4. NATURE OF PROBLEM SOLVED**

SENSIT computes the sensitivity and uncertainty of a calculated integral response (such as a dose
rate) due to input cross sections and their uncertainties. Sensitivity profiles are computed for neutron
and gamma-ray reaction cross sections (of standard multigroup cross-section sets) and for secondary
energy distributions (SED's) of multigroup scattering matrices.

**5. METHOD OF SOLUTION**

In the design sensitivity mode, SENSIT computes changes in an integral response due to design
changes and gives the appropriate sensitivity coefficients. Cross-section uncertainty analyses are
performed for three types of input data uncertainties: (a) cross-section covariance matrices for pairs
of multigroup reaction cross sections, (b) spectral shape uncertainty parameters for secondary energy
distributions (integral SED uncertainties), and (c) covariance matrices for energy-dependent response
functions. For all three types of data uncertainties, SENSIT computes the resulting variance and
expected standard deviation in an integral response of interest, based on generalized perturbation
theory. SENSIT uses angular-flux files from one-dimensional discrete-ordinates code systems such as
ONETRAN, ANISN, and DTF and reads multigroup cross-section sets in three different formats.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

On the CDC 7600, sample problems 1 through 6 (each) ran in under 1 second, sample problem
7 required 12.9 seconds CPU time, and sample problem 8 executed in 62 seconds CPU time.

**8. COMPUTER HARDWARE REQUIREMENTS**

SENSIT is operable on the CDC 7600 computer.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A Fortran compiler is required.

**10. REFERENCE**

S. A. W. Gerstl, "SENSIT: A Cross-Section and Design Sensitivity and Uncertainty Analysis
Code," LA-8498-MS (August 1980).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document and one (1.2MB) DOS diskette which contains the source
code and input and output from the sample problems.

**12. DATE OF ABSTRACT**

February 1982; revised February 1983.

**KEYWORDS: ** ADJOINT; DISCRETE ORDINATES; SENSITIVITY ANALYSIS; GAMMA-RAY; MULTIGROUP; NEUTRON; ONE-DIMENSION; PERTURBATION
THEORY