**1. NAME AND TITLE**

LEAF: Fission Product Release Calculator

From a Reactor Containment Building

For Arbitrary Radioactive Decay Chains.

**2. CONTRIBUTOR**

Los Alamos National Laboratory, Los Alamos, New Mexico.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; CDC-6600/7600.

**4. NATURE OF PROBLEM SOLVED**

LEAF computes an analytic solution of the integrated containment building release problem. The
program calculates the fission product inventory in a reactor containment building and in the
containment building filters in addition to the integrated arbitrary radioactive decay chains.

**5. METHOD OF SOLUTION**

The assumption is made that the gas inside the containment building is well mixed and all in one compartment; that the natural deposition of gas-borne isotopes internal to the containment building is ignored; and that the source of an isotope inside the containment building which is a result of leakage from the reactor vessel, its removal rate by the containment cleanup systems, and its leakage from the containment building are constant during short time intervals.

With the above assumptions, the model can be represented by a system of linear differential
equations. An analytic solution is obtained to these equations in terms of matrix operators using the
Volterra method of the multiplicative integral. Recursive formulae are used to accurately evaluate the
matrix operators for arbitrary matrix element values.

**6. RESTRICTIONS OR LIMITATIONS**

No simple restrictions can be placed on LEAF since variable dimensioning is used. A 10 nuclide
problem with 24 time points requires 62 K of memory.

**7. TYPICAL RUNNING TIME**

Execution time is 7 seconds for a 7 nuclide 11 time step problem on a CDC-7600. It is to be
expected that the running time will increase with the square of the number of nuclides in the problem.

**8. COMPUTER HARDWARE REQUIREMENTS**

The code is designed to run on the CDC 6600/7600 and uses 64 K of core storage and standard
I/O devices. The code uses the NOS 1.2-439F and CROS 2.87 Operating Systems.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A FORTRAN IV compiler is required.

**10. REFERENCE**

C. E. Lee, C. E. Apperson, Jr., and J. E. Foley, "LEAF: A Computer Program to Calculate
Fission Product Release from a Reactor Containment Building for Arbitrary Radioactive Decay
Chains," LA-NUREG-6570-MS (November 1976).

**11. CONTENTS OF CODE PACKAGE**

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

**12. DATE OF ABSTRACT**

December 1981.

**KEYWORDS: ** FISSION PRODUCTS; RADIONUCLIDES; ISOTOPE INVENTORY;
RADIOACTIVITY RELEASE