**1. NAME AND TITLE**

ERIC-2: Calculator of Resonance Integral and Effective Capture and Fission Cross Sections
for Fissile and Non-Fissile Nuclides -- Thermal or Fast Reactors.

**2. CONTRIBUTOR**

United Kingdom Atomic Energy Authority, Winfrith, Dorchester, Dorset, England, through the
NEA Computer Program Library, Ispra (Varese), Italy.

**3. CODING LANGUAGE AND COMPUTER**

Fortran IV; IBM 360/370.

**4. NATURE OF PROBLEM SOLVED**

ERIC-1 computed the effective resonance integrals for non-fissile nuclides in the resolved
resonance region only. Eric-2 is based on the same theory but it has been extended so that 1) fissile
as well as non-fissile nuclides may be included, 2) for the resolved resonances the values of lambda
associated with the absorber atoms may be calculated in place of the conventional NR or IM
approximations, 3) the calculation of the effective resonance integral has been extended to cover the
unresolved region with the upper energy limit being decided by the applicability of the theory, 4)
effective, or group-averaged, capture and fission cross-sections for narrow energy groups may be
calculated from the resonance integrals, and 5) the program may be used for both thermal and fast
reactor calculations. In addition to providing group data for fast and thermal reactor calculations,
ERIC-2 can be used for general investigations of resonance integrals and their associated Doppler
effect.

**5. METHOD OF SOLUTION**

The "intermediate-resonance" theory of Goldstein and Cohen is incorporated, and in the region of
unresolved resonances the partial widths are averaged over their respective distribution functions. The
numerical method described by Greebler and Hutchins is used to obtain some useful approximations
involved in computing the averages over the width distribution functions.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

No study has been made by RSIC of typical running times for ERIC-2.

**8. COMPUTER HARDWARE REQUIREMENTS**

ERIC-2 is operable on the IBM 360/370 computers.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A Fortran IV compiler is required.

**10. REFERENCES**

**a. Included in the documentation:**

H. M. Sumner, "ERIC 2 - A Fortran Program to Calculate Resonance Integrals and from them Effective Capture and Fission Cross Sections," AEEW - R 323 (July 1964).

**b. Background information:**

R. Goldstein and E. R. Cohen, "Theory of Resonance Absorption of Neutrons," *Nucl. Sci. & Eng.*
Vol. 13 (1962) 132-140.

P. Greebler and B. A. Hutchins, *Proc. Seminar on Physics of Fast and Intermediate Reactors,
Vienna, Vol. 3*, (1961) 121.

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document (10.a) and one (1.2MB) DOS diskette which contains the
source code and sample problem input and output.

**12. DATE OF ABSTRACT**

March 1984.

**KEYWORDS**: NEUTRON CROSS SECTION PROCESSING; NUCLEAR MODELS