NFCSS, Background, Objective and Scope
The International symposium on "Nuclear fuel cycle and reactors strategies: adjusting to new realities" was held from 3 to 6 June 1997 in Vienna. For the preparation of this symposium, an International Steering Group with representatives of 12 countries and 3 international organisations (IAEA, OECD/NEA and WNA) co-ordinated, from 1995, the work of six Working Groups. They studied different scenarios of energy consumption including nuclear electricity production. Nuclear electricity production and the associated nuclear fuel cycle requirements should then to be estimated.
Working Group 2 did a comparison of the existing calculation tools for that purpose. At that time, none of them were able to give simple and accurate estimations. Working Group 2, then, asked the Agency to adapt its old CYBA calculation model to take into account the two options for nuclear fuel back end strategy: direct disposal and reprocessing & recycling.
A new simulation system, named NFCSS (formerly known as VISTA), was developed in 1996. It was then intensively used to quantify the different scenarios fixed by the Working Groups.
The new program should be able to calculate, by year over a very long period, nuclear fuel cycle requirements for all types of reactors. Calculations could be performed for a reactor, reactor park in a country or worldwide nuclear power plant park. Natural uranium, conversion, enrichment and fuel fabrication quantities should be estimated. Furthermore, the quantities and qualities (isotopic composition) of unloaded fuels should be evaluated to let the user apply a recycling strategy if desired.
Data inputs should be reduced to a few basic data in order to let non-nuclear fuel specialists to develop different energy scenarios. The calculation speed of the system should be quick enough to enable making comparisons of different options in a considerably short time. So the new simulation system should be designed to be an optimum mixture of accuracy, simplicity and speed.
NFCSS calculations can cover the period ranging from the beginning of nuclear energy production to 2050 or 2100. In order to support estimations for the future term, NFCSS stores historical data in its database.
Historical data mainly come from the existing Agency database (PRIS). Other authoritative publications and consultant reports are also the sources for historical data. Future projection data can be calculated by using publications from different institutions. The IAEA’s "Energy, Electricity and Nuclear Power Estimates up to 2030" is one of the authoritative publications which is used to calculate future nuclear power projection data in NFCSS.
Fresh fuel requirements and spent fuel isotopic composition are then automatically calculated from a set of internal parameters that have been selected by experts and introduced in the program. The user may then choose to use spent fuel stockpiles to develop a recycling strategy. The estimation of accumulation of actinides including minor actinides is one of the capabilities of the simulation. Those accumulation estimations might be used to compare any future fuel cycle options for transmutation of minor actinides.
With its capacity to estimate future fuel cycle material and service requirements NFCSS can bu utilized as a tool for Innovative Nuclear Reactors and Fuel Cycles (INPRO). It has already been announced to INPRO participants in several technical meetings.