NESC0191 AX-TNT.

1. NAME OR DESIGNATION OF PROGRAM:  AX-TNT.

3. DESCRIPTION OF PROGRAM OR FUNCTION

AX-TNT solves:
(a) the coupled hydrodynamic, thermodynamicand neutronic equations which describe a spherical, super-prompt critical reactor system during an excursion.
(b) the coupled equations of motion, and ideal gas equation of state for the detonation of a spherical charge in a gas.

4. METHODS

(a) As in the AX1 code the Sn neutronics section of the code calculates the inverse period and the relative power distribution. The inverse period and power distribution are used for calculating the power level and for assigning the energy added to a given region. During short time intervals hydrodynamic and thermodynamic calculations determine the acceleration, velocity, position, density, pressure, internal energy, kinetic energy and temperature of individual regions or mass points. Code tests send the problem to additional thermodynamic-hydrodynamic calculations or to neutronics calculations as the problem progresses.
Several different equations of state and combinations of equations of state are used in the hydrodynamic-thermodynamic section of the code, namely - the linear, Clausius-Clapeyron, and ideal gas equations of state.
(b) The neutronics section of the AX-TNT code is entirely bypassed An ideal gas equation of state is used in conjunction with the Von Neumann and Richtmyer viscous pressure in the hydrodynamics -thermodynamics sections of the code, to trace the blast wave resulting from the detonation of a spherical charge.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

   Maximum number of energy groups 7  maximum number of mass points 320  maximum number of substances + mixtures
the effects of delayed neutrons and heat transfer are completely neglected.

6. TYPICAL RUNNING TIME

(a) Varies with accuracy criteria, number of mass points and number of energy groups. A typical problem consisting of 20 reactor mass points, 300 gas mass points, and six energy groups takes about 60 minutes.
(b) A typical TNT blast-wave problem consisting of 10 TNT regions and 29 argon regions takes about 30 minutes.

7. UNUSUAL FEATURES OF THE PROGRAM

The AX-TNT program is basically the same as the AX1 program with the following modifications, (a) a combination of the Clausius-Clapeyron and linear equations of state are used in the reactor. Gas regions enclosing the reactor make use of an ideal gas equation of state. A two-temperature region Clausius-Clapeyron expression is used with the triple point as the dividing point between the low and high temperature expression. Several linear sections are used to approximate the heat capacity. The Sn convergence on the fuel enrichment has been incorporated into the code as well as modifications to take into account Doppler contributions to inverse period and a ramp insertion of reactivity. The AX1 code has been expanded from a maximum of 40 regions to 320 regions t allow investigation of shock waves. New control modifications have been included to reduce the increased machine time resulting from the added regions. Minor modifications in the AX-1 hydro-dynamic equations allow the investigation of center hole and implosion problems.
(b) Using an ideal gas equation for TNT and argon the formation,  reflection, refraction, and decay of primary and secondary shock waves can be studied.

8. RELATED AND AUXILIARY PROGRAMS

The AX-TNT program is an extension of the AX1 program (ACC Abstract 102). Equations of state are similar to those considered in the RAC code. Delayed neutron effects can be accounted for by using the AIREK2 code during the beginning of the excursion. H. Borde has described a code for examining blast waves from a spherical charge.

10. REFERENCES

- D. Okrent, J.M. Cook, D. Satkus, R.B. Lazarus and M.B. Wells:
  AX-1, A Computer Program for Coupled Neutronics-Hydrodynamics
  Calculations on the IBM704
  ANL-5977 (May 1959).
- Curtis G. Chezem and William R. Stratton:
  RAC-A Computer Code for Reactor Accident Calculations
  LAMS-2920 (January 1963).
- A. Schwartz:
  Generalized Reactor Kinetics Code AIREK II
  NAA-SR-Memo 4980 (February 1960).
- Harold L. Borde:
  Blast Wave from a Spherical Charge,
  Physics of Fluids, 2, 2, pp. 217-229 (April 1959).

- C.J. Anderson:
  AX-TNT, A Code for the Investigation of Reactor Excursions and
  Blast Waves from a Spherical Charge
  TIM-951 (August 25, 1965).

11. MACHINE REQUIREMENTS:  32k memory, 1 magnetic tape unit.

13. OPERATING SYSTEM OR MONITOR UNDER WHICH PROGRAM IS EXECUTED:  Standard control data COOP monitor.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

ANY OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

15. NAME AND ESTABLISHMENT OF AUTHOR

                 W. J. Fader and C. J. Anderson
                 Pratt and Whitney Aircraft - Canel
                 Middletown, Connecticut

File name	File description	Records
NESC0191_01.001	SOURCE&DATA	1434
NESC0191_01.002	OUTPUT	630