The process for the deregulation and liberalization of the electricity market in Spain started in 1997. This process has brought about very significant changes in the nuclear energy framework, as well as that of other energy sources.

These changes are far from being finished and stability is not going to be a characteristic in the near future. Nuclear energy is used to reacting in a very efficient way to market changes and to new requirements and this has been a new opportunity to demonstrate its capacity for adaptation.

Nuclear generation cost

Electricity price reduction was the main government target for carrying out this revolutionary process. The average price of Spanish electricity has been reduced by 16.6% between 1997 and 2003 in nominal terms, and by 35.6% in real terms (that is taking into account annual inflation). The immediate reaction from the utilities was pressure on the prices of all goods and services provided by different suppliers. If the target for governments is to reduce electricity prices, generating cost reduction is the main goal for utilities.

Everybody knows that nuclear generation costs are lower than the costs of fossil and renewable sources and this has been so for many years (Figure 1). But in trying to anticipate the future, the nuclear industry established some years ago the goal of achieving 1c€/kWh generation costs except for the initial investment. In Spain we are very proud to say that this is already a reality (Figure 2).

Generation costs are no more than the result of dividing all the costs by the number of KWh generated. This could be simply talking about conventional industries, or other energy sources, but nuclear energy is basically technology, and nuclear fuel is not a commodity, it is a technological product. Even though fuel fabrication cost represents only about 3% of the total nuclear kWh generating costs, the impact on the overall plant economics is very high. Fuel utilization, fuel performance and fuel reliability are three key factors for reducing the nuclear generation cost. But because fuel is the core of a very complex system, there are a very important number of factors that must be taken into account (Figure 3). All these factors are not independent of each other, all of them are pieces of a complicated puzzle. ENUSA’s view is that, in order to be successful in achieving further cost reductions, all these factors must be handled in as integrated a way as possible, and for this reason collaboration among the different actors in the nuclear industry is critical.

Key factors for reducing the fuel cycle cost

There follows an analysis of the influence and evolution of some of these factors in Spain:

• Low uranium cost. Spanish utilities decided years ago to create an enriched uranium purchasing pool to get the benefits of synergies and volume. At the same time diversification, long term contracts and a very effective exchange currency management have contributed to reducing the cost of the enriched uranium for the Spanish NPPs by about 30% between 1996 and 2003.
• Fuel fabrication price. Fuel fabrication price is a very small part of the fuel cost, around 20%. Important efforts to reduce costs, as well as the effect of the competitiveness among suppliers, have led to a price reduction that in Spain has been about 20% since 1998.
• Capacity factor. The overall capacity factor of the Spanish nuclear power plants for the entire year 2001 was 93.8%, with an unplanned availability loss factor of 1.7%. Meanwhile, world average nuclear power plant availability factors were about 86.7% (Figure 4). Most of the Spanish NPPs are operating eighteen or twenty-four month cycles and the duration of standard refuelling outages is less than 25 days.

• Installed capacity. The country’s installed nuclear capacity was increased by almost 400 MWe between 1996 and 2001 due to the power up-rating of half of the Spanish NPPs (Figure 5). New power uprates or mini uprates are coming in the next couple of years.
• Discharge burn-up. Nowadays discharge burn-up in Spain is around 50 000 MWd/tU assembly average. This value has been increased little by little and year by year. Core management strategies have been developed and implemented by utilities and ENUSA with the result of increasing burn-up by about 10 000 MWd/tU in less than ten years.

Just to visualise this change, we can compare the fuel strategies of the 5 PWR 3-Loops Spanish reactors in the early 90´s and today :

• 12 month cycles.
• 44 assemblies per reload.
• 1109 days of resistance time in the core.
• 40 000 MWd/tU assembly average discharged burn-up. 45 000 MWd/tU peak rod.
• 3.75% uranium enrichment.

• 18 month cycles.
• 64 assemblies per reload.
• 1263 days of resistance time in the core.
• 51 000 MWd/tU assembly average discharged burn-up. 58 000 MWd/tU peak rod.

• 4.70% uranium enrichment.
• Fuel reliability. This has always been a key parameter for the BWR reactor. Today this is a critical parameter for all type of reactors. ALARA criteria force all nuclear power plants to reduce doses during refuelling outages. Clean cores must be a target for both operators and fuel vendors. Unplanned shutdowns due to fuel failures have a tremendous influence on costs in a deregulated market. In Spain, as well as in other countries, fuel reliability has been enormously improved (Figure 6).

Towards the end of the last century, a lot of fuel design changes were introduced to respond to the utilities’ demands. There is a feeling that changes have been introduced too fast and without the appropriated testing support. This could be true, but what is also true is that vendors have considerably improved their knowledge and extensive databases are supporting our current designs. At least this is so in the case of the current advanced designs that ENUSA is providing to the European market: MAEF/RFA for PWR and GE14 for BWR.

Specifically, in the PWR market, ENUSA is providing its Spanish and European customers with the most advanced design, incorporating the Westinghouse advanced alloy Zirlo^TM as cladding and structural material, robust geometry, intermediate flow mixing grids and a protective grid at the bottom with both structural and debris resistance functions (Figure 7). This design has a lot of experience of operation in Spain and USA with very good records under heavy duty conditions.

• Neutron economy. From the early 90’s, ENUSA introduced a variety of technological solutions in Spain that have had a significant impact on nuclear plant economics. The following have been the main areas of improvement, though the list is not exhaustive:

• Substitution of high neutron absorbing materials, such as inconel, by low absorbing materials such as zircaloy.
• Use of gadolinium as a burnable absorber, and even more so, the movement towards the low gadolinium content concept.
• Highly low leakage fuel management.
• Start-up physics solutions.
• On-line monitoring.
• Staff reductions. Restructuring, consolidations and so on have also been a reality among utilities, and, consequently, significant reductions in human resources are taking place in many companies. Companies are focusing their resources on their core competencies, eliminating redundancies and non-added value activities. In this scenario, collaboration between vendors and buyers is even more important than in the previous model.

Looking for the optimum

After describing the Spanish case, some questions arise very easily. Are the Spanish NPPs at the optimum? Is this optimum valid for all the cases? What are the next steps?

There is not a single fuel cycle strategy that is optimal for all countries and, even within a country, for all utilities. There are three main variants:

• Closed cycles by reprocessing.
• Open cycles by storing fuel in final repositories where associated costs are external to operators.
• Open cycles where costs associated with the second part of the cycle are internal to utilities.

It is clear that the optimum situation can not be the same for the three scenarios. Different studies covering all the scenarios show some similar tendencies. All the main advances discussed in this Paper are valid for the three scenarios. But probably the most important debate is about discharge burn-up. The debate is focused on determining the optimum discharge burn-up in each case. However, summarising, we can state that higher burn-ups than the ones that are commercial and licensed today will be closer to the optimum. For this reason, all the efforts to support this movement are very welcome.

Fuel cycle cost models are country and even utility dependent. ENUSA has developed a FCC model for the Spanish PWR reactors and has performed a parametric analysis to find out the influence of the burn-up on the total FCC. Many cases have been run, but we can summarise this analysis in Table 1.

A couple of conclusions can be obtained from this analysis:

• 5% U₂₃₅ enrichment limit is a very important barrier to increased burn-up beyond the current licensed limits. This is even more important in the case of reactors operating eighteen month cycles.
• Even with this barrier there is still room for improvement and further fuel cycle cost savings. Another 5000 MWd/tU could be added to the current discharge burn-up.

In Spain we are within the first of the three scenarios showed about, but we are moving towards the third one. This transition is not easy and it is dependent on a combination of different initiatives from the different actors.

The way to be successful: partnership

Due to the fact that nuclear fuel is a technological product, the figures mentioned at the beginning of this Paper are the result of a genuine partnership between the Spanish utilities and most of their suppliers, especially ENUSA. In Spain, ENUSA is responsible for enriched uranium procurement, fuel design, licensing and manufacturing, and fuel and core follow-up for most of the Spanish NPPs (Figure 8). This approach provides Spain with the appropriate environment for optimising the reactor core and the use of fuel in order to achieve maximum energy at the lowest possible cost.

The extension of the fuel supply contract signed early this year between ENUSA and the Spanish utilities for the 5 PWR 3-Loops Spanish reactors till year 2009 is the best example of this win-win partnership.

Even after this considerable effort, we still have some way to go. ENUSA is working with it partners in providing its customers with improvements in reliability, flexibility, margins and cost. Specifically we are working on:

• High burn-up capabilities.
• Robust geometry.
• Corrosion resistance.
• Debris resistance.
• Coolant chemistry flexibility.
• Grid-rod interaction.
• Operational margins.
• RIA & LOCA criteria.

Research & development programmes

A considerable effort in R&D programmes is needed in order to address customer and regulatory bodies` requirements. Customer-vendor collaboration is important in this matter in order to be sure that all the programmes are focused on solving these issues. Furthermore, due to the fact that R&D programmes are exceptionally costly, international programmes with a broad participation are required. Robust Fuel Program, Cabri, Halden, NFIR … are very good examples of international collaboration.

ENUSA is carrying out a very important and extensive R&D programme in collaboration with its partners and customers. We are also collaborating with some Spanish companies, like ENRESA and TECNATOM, research centres, and finally with the Spanish Regulatory Commission. In this sense, it is important to refer to our collaboration with several Japanese companies and institutions represented by MHI.

In this framework, ENUSA is starting to work with some Spanish organisations in better understanding fuel performance in the second part of the fuel cycle. This is becoming a new area of R&D for ENUSA. Several programmes are under development to gain a better understanding of the evolution of the main fuel performance parameters at both wet and dry intermediate storage.

Conclusions

We are strongly convinced that the partnership model implemented in Spain many years ago is really worthwhile for both utilities and ENUSA. This model helps Spanish utilities to achieve that which they really need: that is, to compete in a deregulated market. Clearly this is not the only successful model and that it is possible clearly, it could not be extrapolated, but it is at least a model that has been shown work.

Finally, we are also convinced that the way in which we are working world wide in the nuclear industry is the only way to achieve one of our most important goals: the renaissance of nuclear energy. Safe and economic operation of our NPPs, making them competitive, is our permanent task. Public opinion and political acceptance will be our award for achieving this. Putting a lot resources and money to communicate and to try to convince people about the benefits of nuclear energy is needed and required, but facts and results are even more important. Sooner or later, public opinion will face up to reality and at that time our results in terms of safety, economics and environmental effects must be in place.