**1. NAME AND TITLE OF DATA LIBRARY**

VITAMIN-J/COVA/EFF: Neutron Cross-Section Covariance Data in Multigroup Form.

**2. NAME AND TITLE OF DATA RETRIEVAL PROGRAMS**

LAMBDA: Computes eigenvalues of the covariance matrices.

ANGELO2: A program which expands or collapses the cross-section covariance matrices from the energy group structure of the input library into the form required by the user.

PSR-171/NJOY91: A code system for producing pointwise and multigroup neutron and photon cross sections from evaluated nuclear data in ENDF/B-6 format (available from RSIC).

**3. CONTRIBUTOR**

ENEA, Bologna, Italy and OECD NEA Data Bank, Issy-les-Moulineaux, France.

**4. HISTORICAL BACKGROUND AND INFORMATION**

In recent years an increased interest has been shown in the use of uncertainty analysis not only for dosimetry and radiation shielding but also for fast reactor and fusion applications. In order to encourage the wider use of sensitivity and uncertainty analysis, the NEA Data Bank was charged by different NEA working groups to collect information available on neutron cross section covariance data and devise a procedure to make the use of such data to be user convenient and friendly. The original data library in this series of neutron cross section covariance data was produced from a joint effort at NEA Data Bank, in cooperation with IKE Stuttgart and CEA Cadarache in the frame of the JEF project. The original data library based on JEF-1, ENDF/B-IV, ENDF/B-V and IRDF-85 is distributed by RSICC as DLC-157 and by the Data Bank as NEA 1264/03. The new VITAMIN-J/COVA/EFF data library of neutron cross section covariance data was produced by ENEA and made available through a joint effort of the NEA Data Bank, in cooperation with ENEA Bologna, Italy.

**5. APPLICATION OF THE DATA**

The library is designed for radiation shielding applications.

**6. SOURCE AND SCOPE OF DATA**

The library contains the multigroup relative covariance matrix data from EFF-2.4 for 18 materials: H-1, Li-6, C, V, Cr-52, Mn-55, Fe-56, Co-59, Ni-58, Ni-60, Ni-61, Ni-62, Ni-64, Cu-63, Cu-65, Nb-93, Re-185, Re-187. Also included are detector response function covariances from IRDF 90.2 for 19 reactions: Al-27(n,p), Al-27(n,alpha), Mn-55(n,2n), Mn-55(n,gamma), Fe-56(n,p), Ni-58(n,2n), Ni-58(n,p), Zn-64(n,p), Zr-90(n,2n), Nb-93(n,2n), Nb-93(n,n'1), Nb-93(n,gamma), Rh-103(n,n'1), In-115(n,n'1), Au-197(n,2n), Au-197(n,gamma), U-235(n,f), U-238(n,f), U-238(n,gamma). In general, the covariances for the total, elastic, inelastic, and nonelastic scattering cross sections and for the cross sections making a significant contribution to the total absorption cross sections are included. For each material, the energy group structure, relative standard deviations, and relative covariance matrices for different reactions are provided.

**7. DISCUSSION OF THE DATA RETRIEVAL PROGRAMS**

An auxiliary program LAMBDA, which computes the eigenvalues of the covariance matrices, is included in the package. The program ANGELO2 will expand or collapse the multigroup covariance data to a user defined energy structure. This ANGELO2 output can then be used as input to the COVR module of NJOY to produce a BOXER formatted library. The NJOY module BOXR can convert the resulting data to binary form. NJOY is not included in this package.

**8. DATA FORMAT AND COMPUTER**

Card images; All computers (D00197ALLCP00).

**9. TYPICAL RUNNING TIME**

The Lambda run with 175 groups took 19.5 minutes of execution time on the VAX 8810.

**10. REFERENCE**S

I. Kodeli, "LAMBDA Input Description" (October 21, 1996).

I. Kodeli, "ANGELO2 Input Description" (1990).

M. Frisoni and G.C. Panini, "The Covariance Library COVNET from EFF 2.3," EFF-DOC-210(93) (June 1993).

M. Frisoni and G.C. Panini, "Status of Group Libraries from EFF 2.3," EFF-DOC-212(93) (June 1993).

M. Frisoni and G.C. Panini, "Group Nuclear Data Libraries for the European Programme for Fusion," EFF-DOC-367(94) (Presented at the December 8-9, 1994 EFF Meeting, NEA Data Bank, Issy-les-Moulineaux, Paris).

M. Frisoni and G.C. Panini, "COVNET A Library of Covariance Data in Vitamin-J Structure from EFF-2 - Graphs," EFF-DOC-468(96) (February 1996).

I. Kodeli, "Computational Tools for Cross-Section Sensitivity and Uncertainty Evaluation, Final

Report on Task EFF-BB4-F," EFF-DOC-446(96) (December 1996).

**11. CONTENTS OF PACKAGE**

The package contains the references listed above, and the data library and sample input and output. The data library is transmitted on two diskettes as a self-extracting compressed DOS file.

**12. DATE OF ABSTRACT**

January 1991, revised June 1999.

**KEYWORDS: ** BASED ON EFF2; BOXER FORMAT; COVARIANCE MATRICES;
NEUTRON CROSS SECTIONS