NEA-0393 CARNAC.

CARNAC, Neutron Flux and Neutron Spectra in Criticality Accident

NAME OR DESIGNATION OF PROGRAM, COMPUTER, NATURE OF PHYSICAL PROBLEM SOLVED, SOLUTION, RESTRICTIONS, TYPICAL RUNNING TIME, FEATURES, AUXILIARIES, STATUS, REFERENCES, REQUIREMENTS, LANGUAGE, OPERATING SYSTEM, OTHER RESTRICTIONS, NAME AND ESTABLISHMENT OF AUTHOR, MATERIAL, CATEGORIES

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1. NAME OR DESIGNATION OF PROGRAM: CARNAC.

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2. COMPUTERS

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Program name	Package id	Status	Status date
CARNAC	NEA-0393/01	Tested	01-OCT-1976

Machines used:

Package ID	Orig. computer	Test computer
NEA-0393/01	IBM 370 series	IBM 370 series

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3. NATURE OF PHYSICAL PROBLEM SOLVED

Calculation of flux and neutron spectra in the case of a criticality accident.
The method is unsophisticated but fast. The program is divided into  two parts

(1) The code CRITIC is based on the Fermi age equation and evaluates  the neutron number per fission emitted from a moderate critical system and its energy spectrum.
(2) The code NARCISSE uses concrete current albedo, evaluates the  product of neutron reflection on walls of the source containment and calculates the resulting flux at any point, and its energy distribution into 21 groups. The results obtained seem satisfactory, if compared with a Monte Carlo program.

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4. METHODS: METHOD OF SOLUTION

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5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

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6. TYPICAL RUNNING TIME

Times are for an IBM 360/91

CRITIC calculation - less than 30 seconds.
NARCISSE calculation - 3 minutes for flux evaluation at one point chosen inside the containment.

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7. UNUSUAL FEATURES: UNUSUAL FEATURES OF THE PROGRAM

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8. RELATED OR AUXILIARY PROGRAMS: RELATED AND AUXILIARY PROGRAMS

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9. STATUS

Package ID	Status date	Status
NEA-0393/01	01-OCT-1976	Tested at NEADB

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10. REFERENCES

NEA-0393/01, included references:

- J.Bessis:
  Calcul rapide du flux et du spectre neutroniques en cas d'accident
  de criticite (programme CARNAC)
  CEA-N-1612 (May 1973).
- J.Bessis and M. de Mareuil:
  Notice D'exploitation du Programme de Calcul CARNAC
  NOTE S.E.S.R. No. 5 (14 Mars 1973).
- J. Bessis:
Note CEA-N-1612 translated into English ORNL-tr-2825

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11. HARDWARE REQUIREMENTS: MACHINE REQUIREMENTS

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12. PROGRAMMING LANGUAGE(S) USED

Package ID	Computer language
NEA-0393/01	FORTRAN-IV

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13. SOFTWARE REQUIREMENTS: OPERATING SYSTEM OR MONITOR UNDER WHICH PROGRAM IS EXECUTED

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14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

ANY OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

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15. NAME AND ESTABLISHMENT OF AUTHOR

   J.Bessis
   Departement de Surete Nucleaire
   Commissariat a l'Energie Atomique.

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16. MATERIAL AVAILABLE

NEA-0393/01

File name	File description	Records
NEA0393_01.001	SOURCE PROGRAM (F4) EBCDIC	746
NEA0393_01.002	SAMPLE PROBLEM INPUT DATA	127
NEA0393_01.003	SAMPLE PROBLEM PRINTED OUTPUT	1460

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17. CATEGORIES

G. Radiological Safety, Hazard and Accident Analysis

Keywords: accidents, albedo, criticality, neutron flux, neutron spectra, reactor safety.