NEA-0451 CICLON.

1. NAME OR DESIGNATION OF PROGRAM:  CICLON.

3. NATURE OF PHYSICAL PROBLEM SOLVED

Neutronic calculation of successive cycles for survey fuel management studies of PWR transition cycles. With given fuel design characteristics, batch sizes, initial enrichments and burnups of previously irradiated fuel, CICLON calculates cycle lengths or fresh enrichments for specified load factors and end of cycle life condition. Burnup sharing by batch in each cycle is also obtained as well as discharge burnup and isotopics.

4. METHOD OF SOLUTION

A method of approximate balance of reactivity at end of cycle is used, where whole core reactivity is calculated by inversely weighting region-wise reactivities with relative burnups. A search is done in fresh fuel enrichment or in cycle length to match an input, user selected, end of cycle core reactivity depending on reactor size, and end of cycle life condition.
Region-wise reactivities are obtained as a function of regional burnup at end of cycle and initial enrichment from tables provided by the user. Region-wise burnup sharing is either input provided or  calculated by a simplified neutronic model, in which a two dimensional nodal model is condensed by region, with region coupling described with different approximations using empirical parameters that can be obtained through a special option of the program from previous or otherwise calculated cycles.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Arrays are dimensioned through parameters defined in the main program that can easily be changed. Their present values are

maximum number of burnup points in tables - 12
maximum number of batches in call cycles - 110
maximum number of successive cycles to be considered - 20
maximum number of batches, regions or zones in one cycle - 35
maximum number of batches in the rediced summary - 50

6. TYPICAL RUNNING TIME

Depends on the region coupling model and reactivity search option. For a ten cycles calculation with 15 coupled regions in each cycle and cycle length search, total time is less than three minutes CPU time on the UNIVAC 1106, being two thirds of total time.

7. UNUSUAL FEATURES OF THE PROGRAM

A very simple procedure is used to input batch loading in each cycle. Batches can be divided into sub-batches at any reload. Different numbers of in-core or hold out  cycles for every batch are allowed. Irradiation history is saved for every batch and isotopics for the discharge burnup is calculated.
The summary of batch burnups are printed by cycle and the discharge  data is printed in standard format of fuel management.

8. RELATED AND AUXILIARY PROGRAMS

Tabulated sets of K-infinity, final  to initial uranium weight ratio, final enrichment and fissile plutonium contents versus burnup for different initial enrichments should be provided in input. Tables can be obtained from previous files or from cell burnup calculations at nominal operating conditions for the fuel assembly of given design. Selection of reload strategies and regionwise loading schemes should be done previously by the user. A complete set of data summarizing all cycles considered can be punched in the format of the program FUELCOST.

- Jose M. Aragones:
  CICLON - A Neutronic Fuel Management Program for PWR's Consecutive
  Cycles
  JEN 336 (February 1976).
- In-Core Fuel Management Programs for Nuclear Power Reactors
  IAEA-TECDOC-314 (October 1984).

11. MACHINE REQUIREMENTS

Less than 20,000 36-bit words on the UNIVAC 1106 and standard input, output, and punch devices.

13. OPERATING SYSTEM OR MONITOR UNDER WHICH PROGRAM IS EXECUTED:  EXEC-8 system of UNIVAC.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

ANY OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

15. NAME AND ESTABLISHMENT OF AUTHOR

This code system has been included in the Coordinated Research Programme (CRP) on  "Codes Adaptable  to Small and  Medium-Size Computers Available in Developing Countries for In-Core Fuel Management" of the International Atomic Energy Agency.

   Jose M. Aragones
   Junta de Energia Nuclear
   Avda. Complutense, 22
   Madrid-3
   Spain.

File name	File description	Records
NEA0451_01.001	SOURCE PROGRAM (F4) + INPUT DATA (3 CASES)	1606
NEA0451_01.002	SAMPLE PROBLEM PRINTED OUTPUT (CASE 1)	1454
NEA0451_01.003	SAMPLE PROBLEM PRINTED OUTPUT (CASE 2)	929
NEA0451_01.004	SAMPLE PROBLEM PRINTED OUTPUT (CASE 3)	559