NESC0873 COAST-4.

1. NAME OR DESIGNATION OF PROGRAM:  COAST-4.
A Code for the COsting And Sizing of TOkamaks.

3. DESCRIPTION OF PROGRAM OR FUNCTION

COAST produces a generalized description of a D-T burning tokamak reactor and facility. In each complete calculation, the geometry, dimensions, and ratings of approximately fifty subsystems are determined. In addition, performance data associated with the tokamak and facility operation  and a detailed cost estimate, subsystem-by-subsystem, are provided.  The cost estimates include the evaluation of direct capital costs, indirect capital costs, time-related costs, and operating costs Devices which can be sized and costed include: TFTR (Tokamak Fusion  Test Reactor), The Next Step (TNS) type of devices, fusion-fission hybrids, engineering demonstration reactors, power producing reactors, and commercial (power and fissile fuel breeding) reactors. Both the ignition mode and the neutral-beam-driven mode of plasma operation are modeled. The plasma engineering calculations involve zero-dimensional models which account for energy balance, particle balance, alpha-particle effects, slowing-down theory, plasma-plasma  and beam-plasma fusion reaction rates, impurity effects, profile effects, and n(e)-tau(E) scaling. The tokamak engineering calculations account for poloidal and toroidal magnetic field coil assemblies (both superconducting and copper conductors are possible), neutral beam injectors, blanket/shield assemblies, plasma fueling, divertors, heat dissipation systems, and related power supplies. The modeling for the shaping field coils includes the positioning of each coil relative to the other device components, as well as scaling the coil currents from a reference set of current magnitudes and positions (which are supplied as input and should be  consistent with a coil set providing equilibrium and stability conditions for the plasma). The reactor cell containing the tokamak  device, the turbine-generator plant and facility, and balance-of-plant systems are taken into account.

4. METHOD OF SOLUTION

The COAST code "builds" the tokamak around the  plasma and calculates the engineering features of the plasma support systems which allow the plasma to operate as parameterized in the plasma engineering calculations. Since the plasma engineering models include the time-dependent behavior of the plasma during pulse start-up, a complete description of the plasma is provided. As each  component is added to the tokamak it is specified to be consistent with the plasma requirements, the components previously sized, and the engineering ground rules and assumptions supplied as input data. The ground rules and assumptions include magnetic field limits, mechanical stress limits, current density limits, geometry limits, etc. The sizing of the device involves a number of iterative calculations to provide a self-consistent solution, and requires one set of numerical integration calculations. Those calculations allow  the mutual couplings between individual poloidal field coils and the plasma, as well as between the different coils themselves, to be accurately estimated. The sizing calculations are completed prior to the estimate of costs calculations. Costing involves the summation of component costs where size dependencies, unit cost data, and the  sizing results are taken into account. Linear scaling with dimensions, masses, volumes, or ratings, as well as non-linear effects and economy-of-scale factors are involved. The COAST code allows up to five device types (defined by the toroidal field coil assembly and blanket/shield system), five device sizes per device type, and six different values for the number of toroidal field coil sets per size and type per calculation to be handled in a single run. The code is oriented toward both trade-off calculations involving the key plasma and device parameters, as well as toward detailed calculations for a specific device type, size and engineering features. The detailed calculations are designed to provide self-consistent, component-by-component data for lay-out work, the determination of space and geometric allocations and allowances, and values for the various power supply and cooling ratings.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The code calculations are limited to the sizing and designing of D-T burning  tokamak devices. In order to generalize the description of the various subsystems and to provide the logic for various combinations of these subsystems in a given calculation, the sizing models are not detailed to the extent possible in a code modeling each individual system. The detail to which a subsystem is modeled has been dictated by the importance of that system in the various studies and the effect the system has on the capital cost associated with the device and facility. The present version of COAST has the following tokamak reactor sizing and engineering limitations: 1) neutral beam heating only, no RF heating modeled; 2) poloidal shaping field coils must be either completely within the toroidal field coil bore or completely outside of it and the turns must be completely superconducting or normal copper; 3) the blanket assembly used for energy multiplication and/or fissile fuel breeding is located on the outer half of the torus only; 4) the mechanical design of the magnetic field coils is limited and explicitly accounts for coil tension due to fields only; 5) the models do not explicitly account for remote maintenance considerations or features associated with the modularization of the device; 6) the turbine- generator plant and the various heat transfer loops associated with  the balance-of-plant are not modeled in enough detail to provide self-consistent mechanical and thermal engineering data; 7) the modeling for pellet fueling is not incorporated; 8) a completely generalized operating cost model is not incorporated. A number of existing models in COAST have been identified as requiring an update incorporating existing calculational models; i.e. 1) refined mechanical design model for the toroidal field coil assembly, 2) upgraded models for magnetic field coil power supplies, 3) a more generalized fuelhandling system model, and 4) a generalized model accounting for all operating costs.

6. TYPICAL RUNNING TIME

Up to one second of CDC-7600 time is required for a calculation involving a single device for a given size and one set for toroidal field coils. For multiple device sizing and costing calculations in a single run, this time is greatly reduced; e.g., five device sizes (vary major and minor radius) for a single device  type and one toroidal field coil set (fixed number of TF coils - e.g., 12) will require approximately two seconds of CDC-7600 time. Compilation requires times between 11 and 14 seconds.

NEA-DB executed the test case included in this package  on CDC CYBER 740 in 10 seconds of CPU time.

7. UNUSUAL FEATURES OF THE PROGRAM:

8. RELATED AND AUXILIARY PROGRAMS

The COAST code presently in operation is the fourth version.

10. REFERENCES

- S.C. Schulte, T.L. Willke, and J.R. Young:
  "Fusion Reactor Design Studies-Standard Accounts for Cost
   Estimates"
  PNL-2646, May 1978
- "Four Ignition TNS Tokamak Reactor Systems - Design Summary"
  WFPS-TME-071, October 1977
- D.A. Sink, E.M. Iwinski, D.L. Chaplin, G. Gibson:
  "The COAST Code for the Costing and Sizing of D-T Burning
   Tokamaks"
  Supplement to Nuclear Fusion on the Conference and Workshop on
  Fusion Reactor Design Concepts, University of Wisconsin, October
  l977, p.101
- D.L. Chaplin, H.J. Garber, G. Gibson, E.M. Iwinski, D.A. Sink:
  "Reactor System Size and Cost Trends for TNS Tokamaks"
  Trans. Am. Nucl. Soc. 27, 24 (1977)
- D.A. SINK AND E.M. IWINSKI:
  "A Computer Code for the Costing and Sizing of TNS Tokamaks"
Proceedings of the 7th Symposium on Engineering Problems of Fusion    Research, Knoxville, TN, October 1977, p. 86
- J.L. Kelly, et al.:
  "Conceptual Design of a Demonstration Tokamak Hybrid Reactor
   (DTHR)--September 1978"
  WFPS-TME-107, December 1978
- D.A. Sink and G. Gibson:
  "Scoping and Sensitivity Analyses for the Demonstration Tokamak
   Hybrid Reactor (DTHR)"
  WFPS-TME-79-012, March 1979
- D.A. Sink:
  "A Potential Commercial Reactor Based on a Small Tokamak Hybrid
   Reactor"
  Trans. Am. Nucl. Soc. 32, 26 (1979)

- D.A. Sink and E.M. Iwinski:
  User's Manual for COAST-4: A Code for Costing and Sizing Tokamaks.
  WFPS:TME-79-023  (September 1979)

11. MACHINE REQUIREMENTS

One additional output file is defined in addition to two standard input/output files. The small core memory storage requirement on the Westinghouse CDC-7600 is 106,500 octal words and on the MFECC is 143,100 octal words.

The test case was run on CDC CYBER 740 in 124,100 (octal) words of main storage.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED

The code runs under SCOPE 2.1.5, Level 270.70 with the FTN 4.6 Compiler, level 452 at the Westinghouse Power Systems Computer Center using a CDC-7600.  To compile the code on the CDC-7600 at MFECC, it was necessary to employ a LASL privately supported version of SLOPE2 and FTN compiler with ancillary routines, some of which were modified to handle the enormous table of variable names used in COAST.

NOS 1.4-531 (CDC CYBER 740).

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

15. NAME AND ESTABLISHMENT OF AUTHORS

     D. A. Sink and E. M. Iwinski
     Fusion Power Systems Department
     Westinghouse Electric Corporation

File name	File description	Records
NESC0873_01.003	INFORMATION FILE	37
NESC0873_01.004	JCL INFORMATION	9
NESC0873_01.005	COAST-4 SOURCE PROGRAM (FORTRAN)	6242
NESC0873_01.006	COAST-4 TEST CASE INPUT DATA	196
NESC0873_01.007	COAST-4 TEST CASE PRINTED OUTPUT	3016