NEA-0655 VSOP.

1. NAME OR DESIGNATION OF PROGRAM:  VSOP program system.

3. DESCRIPTION OF PROBLEM OR FUNCTION

VSOP (Very Superior Old Programs) is a system of codes linked together for the simulation of reactor life histories. It comprises neutron cross section libraries and processing routines, repeated neutron spectrum evaluation, 2-D and 3-D diffusion calculation, depletion and shut-down features, in- core and out-of-pile fuel management, fuel cycle cost analysis, and  thermal hydraulics (steady state and transient). Various techniques  have been employed to accelerate the iterative processes and to optimize the internal data transfer.
The code system has been used extensively for comparison studies of thermal reactors, their fuel cycles, thermal transients, and safety assessment. Besides its use in research and development work  for the Gas Cooled High Temperature Reactor, the system has been applied successfully to Light Water and Heavy Water Reactors, MAGNOX, and RBMK.

4. METHOD OF SOLUTION

The nuclear data for 184 isotopes are contained in two libraries. Fast and epithermal data in a 68 group GAM-I structure have been prepared mainly from ENDF/B-V and JEF-1. Resonance cross section data are given as input. Thermal data in a 30 group THERMOS structure have been collapsed from a 96 group THERMALIZATION (GATHER) library by a relevant neutron energy spectrum generated by the THERMALIZATION code. Graphite scattering matrices are based on the Young phonon spectrum in graphite.

The neutron spectrum is calculated by a combination of the GAM and THERMOS codes. They can simultaneously be employed for many core regions differing in temperature, burnup, and fuel element lay-out.  The thermal cell code THERMOS has been extended to treat the grain structure of the coated particles inside the fuel elements, and the  epithermal GAM code uses modified cross sections for the resonance absorbers prepared from double heterogeneous ZUT-DGL calculations.

The diffusion module of the code is CITATION with 2 - 8 energy groups. It provides the neutron flux for 1515 compositions in 2-D cases, r-z (9999 compositions in 3-D cases, x-y-z). The burnup scheme has been developed from the FEVER code. The build-up history  of up to 49 fission product nuclides in the compositions is followed explicitly. The diffusion part of the program system can be repeated at many short burnup time steps, and the spectrum module can be repeated at larger time steps, when some significant change in the spectrum is expected.

The fuel management and cost module performs the fuel shuffling and general evaluations of the reactor and fuel element life history. The fuel management simulates the currently known shuffling and out of pile routes for various reactors. It has further been extended to include the typical features of the pebble bed reactor such as burnup dependent optional reloading of elements, separated treatment of different fuel streams, and recycling in new fuel element types according to a consistent mass balance and timing.

Optionally, several different types of data files can be set up with characteristic data of the reactor life. These are used for more detailed investigations and display programs. The restart option allows the study of special phases of the reactor life, e.g.  changes of the fueling scheme, of the burnup, of the power output, of the coolant temperature, and of the corresponding reactivity effects. The fuel cycle cost data set is made for the present worth  KPD code. Two-dimensional thermal hydraulics studies for operating and emergency conditions can be performed with the THERMIX code. The averaged temperatures of the different spectrum zones in the core are returned from the thermal hydraulics to the subsequent step of the reactor history.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

In epithermal energy range the cell spectrum calculation is missing. If needed, it must be simulated by disadvantage factors being obtained in other codes.  Further, dynamic common must be defined for the commons VARDIM, COCI, and for VARPRI (in the auxiliary program PRIOR). This is not needed under the workstation operating systems.

6. TYPICAL RUNNING TIME

The simulation of a 10 year reactor life history with 12 spectrum runs and 20 diffusion calculations requires around 9 minutes. of CPU time on the IBM E/9000-620.

The 12 test case included in this package have been executed by NEA-DB on a DEC VAX 6000-510 computer in about three hours of CPU time.

7. UNUSUAL FEATURES OF THE PROGRAM

No unusual features, since the program system is based on well-established and proven codes.

8. RELATED AND AUXILIARY PROGRAMS

VSOP contains the codes: DATA-2, BIRGIT, TRIGIT, ZUT-DGL, GAM-1, THERMOS, FEVER, KPD, THERMIX, LIFE,  PRIOR and ATALS. The code system uses thermal data collapsed from a  THERMALIZATION/GATHER library using a spectrum generated by the THERMALIZATION code.

The precursor of VSOP was the MAFIA-II code.

10. REFERENCES

- L. Massimo
"MAFIA-II, A One-Dimensional Burnup Code"
Argonne National Laboratory, ANL-7050 (1966).
- G. D. Joanou, et al.:
"GATHER-II, an IBM-7090 Fortran II Program for the Computation of
Thermal Spectra and Associated Multigroup Cross Sections"
General Atomic GA-4132 (1963).
- J. Darvas
"DATA-2, Head Programm zum VSOP Zyklus fuer
Hochtemperaturreaktoren"
KFA Internal Report, KFA-IRE-70-4 (1970).
- G.D. Joanou, J.S. Dudek:
"GAM - A Consistent P1 Multigroup Code for the Calculation of Fast
Neutron Spectra and Multigroup Constants"
General Atomic GA-1850 (1961).
- H C. Honeck:
"THERMOS - A Thermalization Transport Theory Code for Reactor
Lattice Calculation"
Brookhaven National Laboratory BNL-5826 (1961).
- F. Todt:
"FEVER - A One-Dimensional Few Group Depletion Program for Reactor
Analysis"
General Dynamics - General Atomic, GA-2749 (1962).
- U. Hansen:
"The VSOP System Present Worth Fuel Cycle Calculation Methods and
Codes, KPD"
Atomic Energy Establishment Winfrith, England, Dragon Project
Report 915 (1975).
- K. Petersen, A. Verfondern:
"THERMIX, ein Computerprogramm zur Berechnung des instationaeren
Temperaturverhaltens gasdurchstroemter Kugelschuettungen"
to be published.
- E. Teuchert, K.A. Haas:
"ZUT-DGL-V.S.O.P. Programmzyklus fuer die Resonanzabsorption in
heterogenen Anordnungen"
Internal Report, KFA-IRE-70-1 (1970).

- E. Teuchert et al:
  V.S.O.P.('94) - Computer Code System for Reactor Physics and Fuel
  Cycle Simulation - Input Manual and Comments
  (April 1994).

11. MACHINE REQUIREMENTS

Main storage requirement in IBM E/9000-620 is 17 Mbytes for the test case. In the subroutine NACHW the code applies the IBM system routine "MASKE" for suppression of underflows. The subroutines FRIST, ZEITN, ZEIT represent machine dependent time routines. DATUM represents the date, and JOBNAM the name of the job. For the transfer to other machines, they are added  as dummy routines which yield zeroes.
NEA 0655/04: NEA-DB installed the program on a DEC VAX 6000-510 computer.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED

MVS at the IBM E/9000-620. AIX V3.2.5 at the IBM RISC System/6000.

The program was installed by NEA-DB on a VAX 6000 running under VMS 6.1. The source code was compiled with the VAX/VMS FORTRAN compiler Version 6.2.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

NEA 0655/04: In this version of the program, output format statements have been translated from the original German into English.

15. NAME AND ESTABLISHMENT OF AUTHOR

          E. Teuchert, K.A. Haas
          Forschungszentrum Juelich GmbH. (KFA)
          Institut fuer Sicherheitsforschung ind Reaktortechnik
          D-52425 Juelich
          Germany

File name	File description	Records
NEA0655_04.001	Information file	248
NEA0655_04.002	GAM-library (68 groups) in ASCII	49799
NEA0655_04.003	THERMALIZATION-library (96 groups) in ASCII	119388
NEA0655_04.004	Th-232 Resonance data (formatted)	262
NEA0655_04.005	U-238 Resonance data (formatted)	165
NEA0655_04.006	General organization	1432
NEA0655_04.007	Input	2892
NEA0655_04.008	Organization of spectrum calculation 1	1066
NEA0655_04.009	Organization of spectrum calculation 2	1622
NEA0655_04.010	Neutron spectrum 1	987
NEA0655_04.011	Neutron spectrum 2	2196
NEA0655_04.012	Burnup 1	2973
NEA0655_04.013	Burnup 2	3011
NEA0655_04.014	Fuel management, fuel cycle costs 1	1564
NEA0655_04.015	Fuel management, fuel cycle costs 2	2459
NEA0655_04.016	Fuel management, fuel cycle costs 3	2341
NEA0655_04.017	Thermal hydraulics 1	2459
NEA0655_04.018	Thermal hydraulics 2	2358
NEA0655_04.019	Thermal hydraulics 3	2443
NEA0655_04.020	Thermal hydraulics 4	2567
NEA0655_04.021	Thermal hydraulics 5	2463
NEA0655_04.022	Thermal hydraulics 6	2439
NEA0655_04.023	Decay heat	556
NEA0655_04.024	Diffusion calculation 1	2922
NEA0655_04.025	Diffusion calculation 2	2855
NEA0655_04.026	Diffusion calculation 3	3335
NEA0655_04.027	Diffusion calculation 4	2497
NEA0655_04.028	Diffusion calculation 5	2906
NEA0655_04.029	Coupling between thermal hydrau. & neutronic	926
NEA0655_04.030	Dummy subroutines for VAX	16
NEA0655_04.031	Fuel elements and input materials	1562
NEA0655_04.032	Resonance absorption cross sections 1	2254
NEA0655_04.033	Resonance absorption cross sections 2	2440
NEA0655_04.034	Reactor geometry, 2-dim	2124
NEA0655_04.035	Reactor geometry, 3-dim	359
NEA0655_04.036	Converting program for lib GAM.LIB	55
NEA0655_04.037	Converting program for lib THERMA.LIB	53
NEA0655_04.038	Compiling fuel life for decay heat evaluat.	742
NEA0655_04.039	Compiling fuel life for isotropic burnup	355
NEA0655_04.040	Printout of 3D distribution of power	433
NEA0655_04.041	Command file to install and run tests (IBM)	1873
NEA0655_04.042	Command file for compile and link steps(VAX)	62
NEA0655_04.043	Command file to run test cases (VAX)	236
NEA0655_04.044	Data to prepare UNIT 30	4
NEA0655_04.045	Data to calculate resonance integrals	31
NEA0655_04.046	Data to calculate resonance integrals	18
NEA0655_04.047	Data for fuel element design	40
NEA0655_04.048	Data to prepare a 30 group THERMOS-lib	8
NEA0655_04.049	Data to create the volume matrix	50
NEA0655_04.050	Data for geometric data design	50
NEA0655_04.051	Data to restart OTTO case with 2D.	30
NEA0655_04.052	Data to restart LOCA	30
NEA0655_04.053	Data to prepare 30 group THERMOS-lib	37
NEA0655_04.054	Data for startup core of the 100 MW OTTO	267
NEA0655_04.055	Data to restart OTTO case with 2D	137
NEA0655_04.056	Data to restart calc. of temp. coefficients	128
NEA0655_04.057	Data to restart lib. for LIFE(fuel elements)	23
NEA0655_04.058	Data to restart LOCA	188
NEA0655_04.059	Data to compile fuel life history for decay	4
NEA0655_04.060	Tests output	87140