NEMS Models
Other EIA Models
NEMS Contacts

Download the entire report in PDF format

Related Links

Forecasts Publications
EIA Publications

SNAPPS forecasts the short-term monthly and annual electric power generation by U.S. commercial nuclear power plants. SNAPPS is a relatively simple, straightforward accounting model programmed in FORTRAN. The model consists of codes that provide accounting for each nuclear reactor's generation for the projection period.

Last Model Update:

March 1991

Part of Another Model?

No

Sponsor:

• Office: Office of Coal, Nuclear, Electric and Alternate Fuels
• Division: Coal, Nuclear and Renewables Division
• Model Contact: Roger Diedrich
• Telephone: (202) 426-1176
• E-Mail Address: roger.diedrich@eia.doe.gov

Documentation:

• Energy Information Administration, Short-Term Nuclear Annual Power Production Simulation Documentation, Version 4 (Washington, DC, June 1990)
• Energy Information Administration, Short-Term Nuclear Annual Power Production Simulation Documentation (Washington, DC, November 1984) and Addendum (September 1986).

Archive Media and Installation Manual(s):

• SNAP893 — Archived for the Short-Term Energy Outlook (July 1989)
• SNAP9103 — Archived for the Short-Term Energy Outlook (January 1991)
• SNAP92Q4 — Archived for the Short-Term Energy Outlook (4th Quarter 1992)
• SNAP93Q1 — Archived for the Short-Term Energy Outlook (1st Quarter 1993)
• SNAP93Q2 — Archived for the Short-Term Energy Outlook (2nd Quarter 1993)
• SNAP93Q3 — Archived for the Short-Term Energy Outlook (3rd Quarter 1993).

Coverage:

• Geographic: Total United States, individual States, individual reactors, 10 Federal regions, or 4 Census regions
• Time Unit/Frequency: 18-month forecasts quarterly; 5-year forecasts annually, up to 10 years
• Product(s): Projections of electricity generation from nuclear power plants
• Economic Sector(s): Electric utilities which own or operate nuclear power plants.

Modeling Features:

• Model Structure: The model consists of codes that provide accounting for each nuclear reactor's generation over the projection period
• Modeling Technique: The model develops reactor activity schedules, determining if the reactor is generating power or is in extended shutdown. Individual reactor monthly generation is computed by multiplying the designated capacity (net or gross) times the appropriate capacity factor times the hours the reactor operates in that month. For the near term, about 6 months, the values are calculated in a preprocessor that estimates system-wide monthly capacity factors by applying time-series techniques to historical data. The relationship between the monthly capacity factor and the percent of capacity on-line is modeled by a Box-Jenkins transfer function. For the remainder of the projection period, SNAPPS uses average, full-cycle capacity factors, which are functions of reactor type (BWR or PWR) and fuel cycle (1st, 2nd, or equilibrium). The resulting reactor generation values are then cumulated into monthly, annual and regional totals. The model contains the option of using positive refueling times in lieu of seasonality factors
• Special Features:
  • Allows the user to project either gross or net electricity generation. Reports aggregate operating capacity factors
  • May be run either in a reactor-specific or an aggregate mode.

Non-DOE Input Sources:

• Nuclear Regulatory Commission, NRC Operations Center Plant Status Report (updated weekly)
  • Scheduled outage data (start date and duration)
• Nuclear Regulatory Commission, Operating Data Reports
  • Historical generation data (reactor name, date, historical generation and type of generation)
• David Andress, Washington Consulting Group, Analysis of Capacity Factors (March 1990)
  • Cycle-specific data (cycle capacity factor)
  • Generic parameters (monthly capacity factor adjustment [seasonality] factors)
• David Andress, System Sciences, Analysis of Capacity Factors (September 1984)
  • Cycle-specific data (cycle capacity factor)
  • Generic parameters (monthly capacity factor adjustment (seasonality) factors).

DOE Data Input Sources:

Forms and Publications:

• Energy Information Administration, Form EIA-759, Monthly Power Plant Report
  • Historical generation data (1986 on: reactor name, date, historical generation and type of generation)
• Office of Civilian Radioactive Waste Management, Form RW-859, Nuclear Fuel Data
  • Cycle-specific data (cycle number, cycle start date, cycle generation time, cycle capacity factor, cycle full-power days, refueling start date and refueling time)
• Energy Information Administration, Form EIA-860A, Annual Electric Generator Report — Utility
  • Basic reactor characteristics (reactor capacities)

Models and Other:

• Energy Information Administration, International Nuclear Model (INM) maintained by the Office of Coal, Nuclear, Electric, and Alternate Fuels
  • Basic reactor characteristics (reactor type, reactor name, reactor capacities, DOE region, start dates [initial criticality, first electricity and commercial operation], State code and reactor retirement date)
• Energy Information Administration, Office of Coal, Nuclear, Electric and Alternate Fuels
  • Generic parameters
  • Default capacity factor
  • Default full power days
  • Default refueling time
  • Monthly capacity factor adjustment (seasonality) factors
  • Annual capacity factor adjustment (trend) factors.

Computing Environment:

• Hardware Used: IBM 3084QX
• Operating System: MVS/XA
• Language/Software Used: VS FORTRAN (Uses the G-1 compiler)
• Memory Requirement: 1600 Kb
• Storage Requirement: 3380 disk — 5 Mb for model and data
• Estimated Run Time: 7 CPU seconds
• Special Features: None.