NEA-0500 ALARM.

1. NAME OR DESIGNATION OF PROGRAM:  ALARM-B2.

3. NATURE OF PHYSICAL PROBLEM SOLVED

ALARM-B2 which is an improved version of ABARM-B1 is a computer program to analyze thermo-hydraulic phenomena of BWR during a blowdown period under a large-break loss-of-coolant accident condition with special emphasis on the heat transfer phenomena in the core region.

4. METHOD OF SOLUTION

A so called volume-junction method is used to present fluid conservations. The primary system is divided into a number of special elements called "control-volumes". The system of partial differential equations describing fluid conservations for a  stream-tube are integrated over a number of control volumes. The resulting set of simultaneous differential equations that is based on the assumptions of one-dimensional, homogeneous and thermal- equilibrium flow is linearized and solved for a small time increment by a simple explicit numerical technique.
The one-dimensional heat conduction equations describing temperature profiles within solid material are written in finite difference forms which are linearized and solved by the Crank-Nicholson implicit method. In order to simulate the blowdown heat transfer phenomena, the code has correlation packages for heat  transfer coefficient and critical heat flux.
The heat generation in the core is given by a point reactor kinetics model with six groups of delayed neutrons and decay of eleven groups of fission products and actinides. The solution technique of the reactor kinetics is based on the Runge-Kutta method.
ALARM-B2 has the models to simulate various components incorporated in BWRs such as jet pumps, recirculation pumps, steam separators, valves, and so on. The discharge and injection systems are modeled by leak and fill systems, respectively.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

As this has been developed to simulate a blowdown thermo-hydraulic transient during a large break LOCA, users must pay attention when applying the code to any medium or small break LOCAs or to later phases of a large-break  LOCA.

6. TYPICAL RUNNING TIME

The running time depends on the number of time steps and the complexity of the nodalization of the system to be analyzed. A rough estimate of CPU time requirement is about 2 ms/volume.step on FACOM M-380. As a BWR is usually modelled by 10  to 20 volumes with time step size of 0.1 to 1 milliseconds, the total CPU time for a transient of 50 seconds is 0.3 to 1 hours.

NEA-DB executed the test cases included in the package  on IBM 3084Q. The following CPU times were found for the different steps:
         program                    seconds
         -------                    -------
         conversion program         0.68
         ALARM-B2: test case 1      4.3
                   test case 2      3.64
         MERGE                      0.49
         SPLPLOT-1                  0.71

7. UNUSUAL FEATURES: UNUSUAL FEATURES OF THE PROGRAM

8. RELATED AND AUXILIARY PROGRAMS

All input data are read in free format via a generalized subroutine REAG which converts BCD information to integer or floating numbers. The graphic information  is edited by the SPLPACK-1 program which has been developed for plotting the time dependent thermo-hydraulic variables.

10. REFERENCES

- K. Muramatsu et Al.
  User's Manual for SPLPACK-1: A Program Package for Plotting and
  Editing of Experimental and Analytical Data of Various Transient
  Systems,
  JAERI-M 83-166 (1983).
- T. Shimizu
  Verification of LOCA/ECCS Analysis Code ALARM-B2 and THYDE-B1 by
  Comparison with RELAP4/MOD6/U4/J3 (in Japanese),
  JAERI-M 82-094 (1982).
- K. Asai , K. Tsuchiashi
  A Subroutine Reading Data in Free Format (in Japanese),
  JAERI-M 4458 (1971).

- M. Akimoto
  "ALARM-B1, A Computer Program for Boiling Water Reactor Blowdown
  Analysis"
  JAERI-M 6968, March 1977.
- Fumimasa Araya:
  ALARM-B2: A Computer Program for Analysis of Large Break Loca
  of BWR.  JAERI-M 9655  (Sept.1981; Rev. Sept.1984)

11. MACHINE REQUIREMENTS:  The required storage is about 1600K bytes.

Main storage requirements on IBM 3084Q are as follows:
             Conversion program:    128K bytes
             ALARM-B2:             1096K bytes
             MERGE:                 328K bytes
             SPLPLOT-1:             644K bytes

13. OPERATING SYSTEM OR MONITOR UNDER WHICH PROGRAM IS EXECUTED

The program can be executed without specification of optimization using  the FORTRAN-77 compiler of the FACOM M-380 standard operating system.

MVS-SP (IBM 3084Q).

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

ANY OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

15. NAME AND ESTABLISHMENT OF AUTHOR

   F. Araya and M. Akimoto
   Department of Nuclear Safety Evaluation
   Japan Atomic Energy Research Institute
   Tokai-mura, Naka-gun, Ibaraki-ken, Japan

File name	File description	Records
NEA0500_01.001	LIBRARY DATA ( STEAM TABLE IN BCD FORM )	2620
NEA0500_01.002	LIBRARY CONVERSION PROG. BCD TO BINARY (F4)	10
NEA0500_01.003	JCL OF CONVERSION PROGRAM	5
NEA0500_01.004	SOURCE PROGRAM - F4 - EBCDIC	8499
NEA0500_01.005	JCL	6
NEA0500_01.006	SAMPLE PROBLEM INPUT DATA	172
NEA0500_01.007	SAMPLE PROBLEM PRINTED OUTPUT	2032

File name	File description	Records
NEA0500_02.001	INFORMATION FILE	224
NEA0500_02.002	ALARM-B2 SOURCE PROGRAM (CARD IMAGES)	21717
NEA0500_02.003	SPLPACK SOURCE PROGRAM (CARD IMAGES)	5779
NEA0500_02.004	SPLPLOT-1 SOURCE PROGRAM (CARD IMAGES)	5674
NEA0500_02.005	SPLUCL2 SOURCE PROGRAM (CARD IMAGES)	3968
NEA0500_02.006	CONVERSION PROGRAM FOR STEAM TABLES	38
NEA0500_02.007	MERGE SOURCE PROGRAM (CARD IMAGES)	713
NEA0500_02.008	SPLSUBR SOURCE PROGRAM (CARD IMAGES)	252
NEA0500_02.009	LOCF SOURCE (ASSEMBLER)	7
NEA0500_02.010	SETB99 ASSEMBLER ROUTINE	80
NEA0500_02.011	ADDITIONAL SUBROUTINES SOURCE	30
NEA0500_02.012	JCL	323
NEA0500_02.013	ALARM-B2 TEST CASE 1 INPUT DATA	253
NEA0500_02.014	ALARM-B2 TEST CASE 2 INPUT DATA	34
NEA0500_02.015	MERGE TEST CASE INPUT DATA	2
NEA0500_02.016	SPLPLOT-1 TEST CASE INPUT DATA	26
NEA0500_02.017	ALARM-B2 TEST CASE 1 PRINTED OUTPUT	3078
NEA0500_02.018	ALARM-B2 TEST CASE 2 PRINTED OUTPUT	2396
NEA0500_02.019	MERGE TEST CASE PRINTED OUTPUT	111
NEA0500_02.020	STEAM TABLE DATA LIBRARY (FORMATTED)	3867
NEA0500_02.021	SPLPLOT LABELING DATA	272