**1. NAME AND TITLE**

MORSE-CV: Multigroup Neutron and Gamma-Ray Monte Carlo Transport Code with Covariance Calculation. We recommend C00474/ALLCP/02 MORSE-CGA.

**2. CONTRIBUTOR**

Tokyo Institute of Technology, Tokyo, Japan.

**3. CODING LANGUAGE AND COMPUTER**

Fortran 77; Hitachi M-280H. (C00535HM28000)

**4. NATURE OF PROBLEM SOLVED**

MORSE-CV calculates the covariance of the scalar neutron flux spectrum.

**5. METHOD OF SOLUTION**

In the MORSE code, random walk histories are divided into batches. Once the estimate from the j'th history in the i'th batch and the number of independent histories in the i'th batch are obtained, the accumulated estimate in the i'th batch can be computed, and the mean of the estimate can then be calculated. MORSE calculates the variance of the mean and the variance of the spectrum for each energy group. However, the correlation between the mean spectral values for different energy groups is not calculated. MORSE-CV calculates the covariance of the mean spectral values for each energy group. Once the mean and covariance of the spectrum are given, the mean and variance of the integral values of the spectrum can be calculated.

**6. RESTRICTIONS OR LIMITATIONS**

The source is described by input data for several common distributions. The geometry is not described by the "combinatorial geometry" package found in most versions of MORSE but is described by the older "generalized geometry" package which utilizes surfaces instead of volumes.

**7. TYPICAL RUNNING TIME**

No study of running times has been done by RSIC.

**8. COMPUTER HARDWARE REQUIREMENTS**

MORSE-CV runs on the Hitachi M-280H.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A Fortran-77 compiler is necessary.

**10. REFERENCES**

H. Sekimoto and T. Noura, "MORSE-CV, A Multigroup Neutron and Gamma-Ray Monte Carlo Transport Code with Covariance Calculations," Bulletin of the Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, ISSN 0387-6144, Vol. 13, pp. 3-11 (1988).

H. Sekimoto, "Spectral Covariance Associated with the Monte Carlo Method,"
*Nuclear Science and Engineering*: 94,277-281 (1986).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced documents and one DS/HD 3.5-in. (1.44 MB) diskette in self-extracting compressed DOS files which contains the source codes, input and output.

**12. DATE OF ABSTRACT**

November 1988.

**KEYWORDS** MONTE CARLO; MULTIGROUP; NEUTRON; GAMMA-RAY