NESC1125 OCA-P.

1. NAME OR DESIGNATION OF PROGRAM:  OCA-P.

3. DESCRIPTION OF PROGRAM OR FUNCTION

OCA-P is a probabilistic fracture-mechanics code prepared specifically for evaluating the integrity of pressurized-water reactor vessels subjected to overcooling-accident loading conditions. Based on linear-elastic fracture mechanics, it has two- and limited three-dimensional flaw capability, and can treat cladding as a discrete region. Both deterministic and probabilistic analyses can be performed. For deterministic analysis, it is possible to conduct a search for critical values of the fluence and the nil-ductility reference temperature corresponding to incipient initiation of the initial flaw. The probabilistic portion of OCA-P is based on Monte Carlo techniques, and simulated parameters include fluence, flaw depth, fracture toughness, nil-ductility reference temperature, and concentrations of copper, nickel, and phospherous. Plotting capabilities include the construction of critical-crack-depth diagrams (deterministic analysis) and a variety of histograms (probabilistic analysis).

4. METHOD OF SOLUTION

OAC-P accepts as input the reactor primary- system pressure and the reactor pressure-vessel downcomer coolant temperature, as functions of time in the specified transient. Then,  the wall temperatures and stresses are calculated as a function of time and radial position in the wall, and the fracture-mechanics analysis is performed to obtain the stress intensity factors as a function of crack depth and time in the transient. In a deterministic analysis, values of the static crack initiation toughness and the crack arrest toughness are also calculated for all crack depths and times in the transient. A comparison of these values permits an evaluation of flaw behavior.
For a probabilistic analysis, OCA-P generates a large number of reactor pressure vessels, each with a different combination of the various values of the parameters involved in the analysis of flaw behavior. For each of these vessels, a deterministic fracture- mechanics analysis is performed to determine whether vessel "failure" takes place. The conditional probability of "failure" is simply the number of vessels that "fail" divided by the number of vessels generated.

6. TYPICAL RUNNING TIME

The sample problem which analyses one weld using 10,000 trials takes 80 minutes on an IBM PC with a hard disk,  78 minutes on an IBM PC/AT, and 1 minute on an IBM3033.

7. UNUSUAL FEATURES OF THE PROGRAM

Input can be in either English or  SI units. The analysis is performed using English units, but if SI units are specified, conversion is automatic and output will be provided in SI units.

8. RELATED AND AUXILIARY PROGRAMS

OCA-P is a combination of the earlier OCA-II deterministic fracture mechanics code and a Monte Carlo procedure to introduce the probabilistic aspect. OCA-II was a  successor of OCA-I.

10. REFERENCES

- OCA-P, NESC No. 1125.PC, OCA-P IBM PC Version Flexible Disk
  Cartridge Descriptions,
  National Energy Software Center Note 90-88, April 18, 1990.
- D.G. Ball, R.D. Cheverton, J.B. Drake, and S.K. Iskander,
OCA-II, A Code for Calculating The Behavior of 2-D and 3-D Surface    Flows in a Pressure Vessel Subjected to Temperature and Pressure
  Transients
  NUREG/CR-3941 (ONRL-5934), February 1984.

- R. D. Cheverton and D. G. Ball:
  OCA-P, A Deterministic and Probabilistic Fracture-Mechanics Code
  for Applications to Pressure Vessels
  NUREG/CR-3618 (ORNL-5991) (May 1984).
- D. G. Ball and R. D. Cheverton:
  Adaptation of OCA-P, A Probabilistic Fracture-Mechanics Code, to a
  Personal Computer
  NUREG/CR-4468 (ORNL/CSD/TM-233) (December 1985).
- R.D. Cheverton and D.G. Ball:
  OCA-P, A Deterministic and Probabilistic Fracture-Mechanics Code
  for Applications to Pressure Vessels
  NUREG/CR-3618 (ORNL-5991) (May 1984).
- OCA-P, NESC No. 1125.3033, OCA-P IBM3033 Version Tape Description
  and Implementation Information
  NESC Note 90-87 (April 18, 1990).

11. MACHINE REQUIREMENTS:  The PC version requires 512 Kbytes of memory.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  OS/MVS (IBM3033),DOS 3.2 (IBM PC).

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

The IBM3033 version uses three mathematical routines from the proprietary Numerical Algorithems Group (NAG) library. They are G05CBF (ISEED) to set the random seed, GO5CAF(X) a uniform distribution random number generator, and GO5DDF a normal distrbution random number generator. The proprietary CA-DISSPLA graphics software (see http://www.gaeinc.com) is called to produce plots with the IBM3033 version. The IBM PC version does not produce plots.

15. NAME AND ESTABLISHMENT OF AUTHORS

   R. D. Cheverton and D. G. Ball
   Oak Ridge National Laboratory
   Oak Ridge, TN 37831
   USA

source program   mag tapeOCA-P Source Files    (Disk # 1)           SRCTP
object program   mag tapeObject Files          (Disk # 1)           OBJTP
load module      mag tapeExecutable Files      (Disk # 1)           LODTP
test-case data   mag tapeSample Problem Input  (Disk # 1)           DATTP
symb data lib    mag tapeLibrary Data Files    (Disk # 1)           LBSTP
test-case output mag tapeSample Problem Output (Disk # 2)           OUTTP
report                   NUREG/CR-3618 (ORNL-5991), (February 1984) REPPT
report                   NUREG/CR-4468 (ORNL/CSD/TM-233) (Dec. 1985)REPPT

source program   mag tapeONER FORTRAN Source, 1-R Heat Transfer CodeSRCTP
source program   mag tapePFM1 FORTRAN Source, Fracture Mechanics 1  SRCTP
source program   mag tapePFM2 FORTRAN Source, Fracture Mechanics 2  SRCTP
source program   mag tapeKITOBIN FORTRAN Source, Converts 2-D K*    SRCTP
source program   mag tapeKITOBIN2 FORTRAN Source, Converts 3-D K*   SRCTP
source program   mag tapePLTFLWSI FORTRAN Source, Plot PostprocessorSRCTP
source program   mag tapeICLOCK ASSEMBLER Source, Called by PFM     SRCTP
source program   mag tapeIDAY ASSEMBLER Source, Called by PFM       SRCTP
source program   mag tapeTIME ASSEMBLER Source, Called by PFM       SRCTP
test-case data   mag tapeCI860945, Formatted 2-D K*                 DATTP
test-case data   mag tapeLI630719, Formatted 2-D K*                 DATTP
test-case data   mag tapeLI780873, Formatted 2-D K*                 DATTP
test-case data   mag tapeLI8603D, Formatted 2-D K*                  DATTP
test-case data   mag tapeLI860945, Formatted 2-D K*                 DATTP
test-case data   mag tapeLO860945, Formatted 2-D K*                 DATTP
test-case data   mag tapeONER Sample Input                          DATTP
test-case data   mag tapePFM Sample Input                           DATTP
test-case output mag tapePFM Sample Output                          OUTTP
test-case output mag tapePFMSUM Sample Output, Probabilistic summaryOUTTP
test-case output mag tapeCCD Sample Output, Deterministic Summary   OUTTP
report                   NUREG/CR-3618 (ORNL-5991), (May 1984)      REPPT
prog. note               NESC Note 90-87 (April 18, 1990)           NOTPT