NESC0917 RELAP5/MOD1/029.

1. NAME OR DESIGNATION OF PROGRAM:  RELAP5/MOD1/029

3. DESCRIPTION OF PROBLEM OR FUNCTION

RELAP5 was developed to describe the behavior of a light water reactor (LWR) subjected to postulated transients such as loss of coolant from large or small pipe breaks, pump failures, etc. RELAP5 calculates fluid conditions  such as velocities, pressures, densities, qualities, temperatures; thermal conditions such as surface temperatures, temperature distributions, heat fluxes; pump conditions; trip conditions; reactor power and reactivity from point reactor kinetics; and control system variables. In addition to reactor applications, the program can be applied to transient analysis of other thermal- hydraulic systems with water as the fluid.
RELAP5/MOD1 uses a five equation two-phase flow hydrodynamic model consisting of the two phasic continuity equations, the two phasic momentum equations, and an overall energy equation augmented  by the requirement that one of the phases is assumed saturated. In this model only two interphase constitutive relations are required,  those for interphase drag and interphase mass exchange. Models are included for abrupt area changes, choking, mass transfer, interphase drag, wall friction, and branching.

4. METHOD OF SOLUTION

For hydrodynamics, the space approximation uses a staggered mesh, where integral forms of the continuity and energy  equations are approximated over control volumes, and line integral forms of the momentum equations are applied from the midpoint of one control volume to the midpoint of the adjoining control volume. Hydrodynamic equations are advanced in time using a semi-implicit, linearized method. Heat conduction is approximated by finite differences and advanced by the Crank-Nicolson scheme. A modified Runge-Kutta technique for stiff equations is used to solve the reactor kinetics equations. The interaction among hydrodynamics, heat conduction, trips, reactor kinetics, and the control system is  explicit.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The limitations on the number of hydrodynamic volumes, heat structures, trips, minor edits, etc. are primarily dictated by the available memory of the computer. Dynamic allocation of storage is used for all problem- dependent data. Design of the fields used for input data can also impose limits. Problems with over 150 hydrodynamic volumes and over  100 heat structures have been run on a CYBER176 using 270K of SCM and 200K of LCM storage for input processing and less during transient analysis.

6. TYPICAL RUNNING TIME

The computer time depends on the number of volumes, heat structures, and the type of transient. Simulation of a postulated small break loss-of-coolant accident for the LOFT reactor using 87 volumes, 96 junctions, and 32 heat structures required 3152 seconds of CYBER176 time for 3600 seconds of reactor transient analysis. EDHTRK sample problem execution time is approximately 20 CP seconds on a CDC CYBER176 and 39 CP seconds on a CDC CYBER175; WORKSHOP PROBLEM 2 40 CP seconds on a CDC CYBER176 and 71 CP seconds on a CDC CYBER175; WORKSHOP PROBLEM 3 118 CP seconds on a CDC CYBER176 and 215 CP seconds on a CDC CYBER175. Execution of the sample problems on the IBM3033 and IBM370/195 requires from 1 second to 3 minutes of CPU time.

7. UNUSUAL FEATURES OF THE PROGRAM

Automatic time-step control is used for hydrodynamic advancement.

8. RELATED AND AUXILIARY PROGRAMS

The primary improvement in RELAP5 compared to the earlier RELAP4 series (NESC No. 369) is the use of an advanced hydrodynamic model for two-phase flow which allows different velocities and different temperatures for the phases. RELAP5/MOD1 extends the earlier RELAP5/MOD0 capability to include models unique to small break situations, and provides added capability for modeling accumulators, noncondensible gas, nucleonics, control systems, separators, and boron concentrations. MOD1 also contains improvements in the flow regime maps, choked flow models, general running time, and  output edits.

10. REFERENCES

- RELAP5/MOD1/008, NESC No. 917.3033, RELAP5/MOD1/008 Tape
  and Implementation Information,
  National Energy Software Center Note 84-11, February 17, 1984.
- P. Saha, J.H. Jo, L. Neymotin, U.S. Rohatgi, and G. Slovik,
Independent Assessment of TRAC-PD2 and RELAP5/MOD1 Codes at BNL in    FY 1981,
  NUREG/CR-3148, (BNL-NUREG-51645), December 1982.
- J.M. McGlaun and L.N. Kmetyk,
RELAP5 Assessments: Semiscale Natural Circulation Tests S-NC-2 and    S-NC-7,
  NUREG/CR-3258 (SAND83-0833), May 1983.
- R.A. Riemke, h.Chow, and V.H. Ranson,
  RELAP5/MOD1 Code Manual Volume 3: Checkout Problems summary,
  EGG-NSMD-6182, February 1983.
- D.G. Hall and E.C. Johnson,
  RELAP5/mod1 Quick Reference Manual,
  EGG-CDD-6027, October 1982.

- B. Mavko, M. Gregoric and I. Parzer:
  Conversion of RELAP5/MOD1/025 VAX Version to RELAP5/MOD1/029 VAX
  Version
  IJS-DP-5355 (December 1988).
- Graphs of RELAP Output (February 1991).
- D.G. Hall and E.C. Johnson:
  RELAP5/MOD1 Quick Reference Manual
  EGG-CDD-6027 (October 1982)

11. MACHINE REQUIREMENTS

RELAP5 has run on a 64K CDC7600 and a 132K CYBER176 both with and without use of LCM storage, and a 256K CDC CYBER176 without use of ECS storage. The CDC RELAP5 package contains options (implementated through the CDC UPDATE utility program) intended to allow RELAP5 implementation on a CYBER76 operating under SCOPE2, and CYBER175 under NOS or NOS2, and a CYBER170 or similar CYBER series hardware under NOS/BE.
RELAP5 on an IBM3033 or IBM 370/195 requires from 980K or 1500K bytes.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED

NOS/BE (CDC CYBER 176), SCOPE 2.1.5 (CDC7600), NOS2.2 (CDC CYBER175), MVS (IBM3033).

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

RELAP5
contains a limited plotting capability. It has been interfaced to the local INEL system and proprietary graphics software to plot and  compare simulation results with experiment. A number of the NRTS Environmental Subroutines are written in the CDC assembly language COMPASS, including those for input and output processing, and packing and unpacking. RELAP5 is written exclusively in FORTRAN but  uses MASK, SHIFT and Boolean AND and OR operations to pack and unpack integer data. Several of the routines which are CDC operating system or INEL computing environment dependent will require modification or replacement in other environments. The RELAP5 Edition B package is the same as the C176 edition except that it is  written in a format that can be read on non-CDC machines.
The IBM version of RELAP5 contains an assembly language subroutine JTIME which only runs on VM systems. Users with other operating systems must replace this routine, which requests the remaining CPU time of a job, with an alternative routine suited to their computing environment.

15. NAME AND ESTABLISHMENT OF AUTHOR

   C176 & C176B    V.H. Ransom, R.J. Wagner, K.E. Carlson,
                   J.A. Trapp, D.M. Kiser, H.H. Kuo,
                   H.M. Chow, R.A. Nelson, D.G. Hall,
                   S.W. James, and E.C. Johnson
                   EG&G Idaho, Inc.
                   P.O. Box 1625
                   Idaho Falls, Idaho 83415

     3033          L. Garcia de Viedma*
                   N.E.A. Data Bank
                   91191 Gif-sur-Yvette
                   France
* Contact

File name	File description	Records
NESC0917_20.001	Information file	125
NESC0917_20.002	Command file to compile the R5RTL version	9
NESC0917_20.003	Command file to compile the RELAP version	9
NESC0917_20.004	Command file to link the R5RTL version	1
NESC0917_20.005	Command file to link the RELAP version	1
NESC0917_20.006	Command file for file assignement	67
NESC0917_20.007	Command file to run Relap5/MOD1/029	249
NESC0917_20.008	R5RTL Relap version source file	50065
NESC0917_20.009	RELAP Relap version source file	50798
NESC0917_20.010	STEAM source file	24
NESC0917_20.011	ENV subroutine	5219
NESC0917_20.012	ENV2 subroutine	439
NESC0917_20.013	ENV2A subroutine	6
NESC0917_20.014	UNUSED subroutine	1766
NESC0917_20.015	Changes in the RELAP source routines	162
NESC0917_20.016	Changes in the RELAP source routines	256
NESC0917_20.017	Changes in the RELAP source routines	274
NESC0917_20.018	Changes in the R5RTL source routines	743
NESC0917_20.019	UNUSED macro file in assembler	157
NESC0917_20.020	AND macro routine in Assembler	24
NESC0917_20.021	NOT macro routine in assembler	15
NESC0917_20.022	OR macro routine in assembler	17
NESC0917_20.023	SHIFT macro routine in assembler	105
NESC0917_20.024	SHIFTI macro routine in assembler	105
NESC0917_20.025	XOR macro routine in assembler	36
NESC0917_20.026	Binary steam table G_floating precision	54
NESC0917_20.027	Binary steam table no G_floating precision	54
NESC0917_20.028	Decimal steam table	4457
NESC0917_20.029	Sample1 input file	152
NESC0917_20.030	Sample2 input file	992
NESC0917_20.031	Sample3 input file	222
NESC0917_20.032	Sample1 brief output file from RELAP version	152
NESC0917_20.033	Sample2 brief output file from RELAP version	280
NESC0917_20.034	Sample3 brief output file from RELAP version	358
NESC0917_20.035	Sample1 brief output file from R5RTL version	152
NESC0917_20.036	Sample2 brief output file from R5RTL version	280
NESC0917_20.037	Sample3 brief output file from R5RTL version	358
NESC0917_20.038	Sample1 output file from RELAP version	5401
NESC0917_20.039	Sample2 output file from RELAP version	8299
NESC0917_20.040	Sample3 output file from RELAP version	3157
NESC0917_20.041	Sample1 output file from R5RTL version	5401
NESC0917_20.042	Sample2 output file from R5RTL version	8299
NESC0917_20.043	Sample3 output file from R5RTL version	3158