F. Rojo
UNESA

R. Cortes
ENRESA

F. Alvarez-Mir
IBERDROLA

This paper states an Action Plan to reduce the volume of LILW generation in the Spanish Nuclear Power Plants (NPP's). This Plan is mainly based on an agreement between the NPP's and ENRESA, the National Radioactive Waste Management Company. This agreement was justified on the mutual interest of ENRESA and NPP's to reduce the volume of waste and also, because in Spain, the financing system for waste management is a fee levied on the electricity tariffs, thus the NPP's do not support any direct cost of the waste disposal.

The Action Plan has been developed in two phases: the first phase in 1995-1996, and the second phase initiated in 1997 is expected to be fully implemented by 2001, forecasting in that date a radwaste volume reduction of about 50% with regard to the generation of wastes in 1990.

This paper describes the most remarkable projects, costs and related volume reductions.

By the end of 1997, the Spanish utilities associated in UNESA had a total installed power capacity of 46,291 Mwe, of which 35.7 % was hydro, 47.9 % thermal and 16.4 % nuclear. Along 1997, these electrical utilities, commissioned four new fossil-fired units.

The total gross electricity generation in 1997 was of 188,621 millions of kWh, 19.5% was hydro, 51% conventional thermal and 29.5% nuclear. As in previous years, it can be stated that the nuclear plants contributed approximately to almost one third of Spain electricity generation, see Fig. 1. 

In 1997, the electricity generation increased 7% over 1996. However, the most remarkable characteristic of 1997 as regards the overall Electricity Sector, was a rise in electricity consumption of 4.2% over the figures for 1996.

The nine (9) Spanish nuclear units are performing excellently in respect to safety, availability and costs, as it has been usual on the preceding years.

The high level of generation went hand in hand with good load and time-availability factors, which reached 83.54% and 88.16% as a mean, respectively for all the plants over 1997.

Other "Performance Indicators" such as the volume of radioactive wastes shows instead that there is still some margin to approach the target figures provided for this international indicator by the Word Association of Nuclear Operators (WANO).

The management of Radioactive Waste in Spain was entrusted in 1984 to ENRESA, a State-owned company.

The radioactive waste strategies are defined in the "General Radioactive Waste Management Plan" (GRWMP), a Document submitted periodically by ENRESA to the Government for approval. The GRWMP not only considers technical aspects but also economic and financial ones involved in the radwaste management. Estimated volumes of LILW in the 4^th GRWMP presently in force, are summarized on Table II.

The LILW disposal is achieved in a near surface facility with engineered barriers, similar to the French model. The disposal facility is licensed since 1992 at the site named "El Cabril", located at 130 Km northwest of Cordoba, that has been designed to accommodate all the wastes of this type to be generated in Spain for the next 20 years.

El Cabril incorporates the most advanced technologies used for this type of installation. Technically, the facility consists of a system of shallow disposal and guarantees compliance with the necessary safety objectives and criteria such that there will be no significant radiological impact during the period required for the activity of the waste to decay to harmless levels.

The radioactive waste are conditioned into drums, usually of 220 liters (55 gallons) capacity, that are placed inside concrete containers, forming concrete blocks of 24 metric tons weight each. These containers will be placed within the 28 storage platforms designed for the disposal site, each of which has a capacity for 320 containers. Once a platform structure has been filled, an upper sealing slab is installed and made watertight with a synthetic cover. See Fig 2.

According to Royal Decree 1522/84, which authorized the constitution of ENRESA, the cost of the activities arising as a result of radioactive waste management should be financed by those responsible for producing these wastes.

The system established for the nuclear power plants consists of establishing a percentage charge to be applied to the total billing for electrical energy sales of the entire electricity sector.

The electric, nuclear and non-nuclear, energy generation forecast is used to calculate both the annual revenue necessary and the financing quota, which is approved every year by the Government.

At present, electric utilities are acting merely as tax collectors to make up the funds for ENRESA, whose operating costs are considered as external to the electricity generation cost. This accumulated fund is not subject to company tax.

Let's take 1990 as the reference starting point for the sake of comparing and analyzing Spanish NPP's low and intermediate level waste (LILW) generation. In that year a total of 6,775 conditioned waste packages were generated, equivalent to a volume of 1,475 m³.

NPP's were well aware of the importance of reducing the generation of LILW and, consequently, during those years they implemented a series of improvements in the operation and maintenance of their Plant Systems; as a result of those, the generation dropped to 5,234 packages in 1993, which represented an average reduction of 7 % per year. See Table III.

At the same time, in October 1992 when the "El Cabril" Storage Facility was commissioned, waste packages started to be removed from the plant in significant amounts. As this facility began to receive waste during its first operating year, it became clear that the filling procedure had to be optimized, otherwise the facility's capacity might be misused, with a level of activity much lower than its radiological limit. In other words, greater efforts had to be made in the NPP's reduction programs to ensure that a greater amount of specific activity was reached.

To pursue the goal of reducing the volume of LILW generation, and since the actions required to achieve this might call for further investments, ENRESA and the NPP's, represented by UNESA, signed an agreement in June 1994, in which both parties decided to undertake whatever actions are necessary to fulfill this goal. After analyzing the possible actions, the Agreement laid down a system of financing under which ENRESA was responsible for paying the project's costs. However, ENRESA would not have to pay more than the savings that could be made, in terms of LILW management costs, by the reduction in volume (number of packages) achieved. The aforementioned LILW management costs were calculated in accordance with the parameters set out in the General Radioactive Waste Plan.

On the other hand, the NPP's should have to support the potential increase in operation and maintenance costs derived from the implementation of the mentioned investments.

This agreement was justified on the mutual interest, of ENRESA and the NPP's, to reduce the volume of the radioactive waste and also, because in Spain, as it has been said previously, the financing system for waste management is a fee levied on the electricity tariffs; without charging it to NPP's.

The advantages of volume reduction of radioactive waste can be summarized as follows:

• less need for material supplies for waste conditioning.
• less need for handling of temporary storage of waste.
• lower individual and collective radiological doses associated to the waste treatment process.
• lower potential contamination risks.

In addition to these considerations, which can be quantified in an economic appraisal, attention must be paid to social requirements asking for an optimized radwaste management, including their volume reduction.

• less need for transport and handling
• an optimum use of the "El Cabril" facilities

As a result of the analysis accomplished by ENRESA and each Nuclear Power Plant, in January 1995, the "Global Volume Reduction Action Plan" was issued. This Plan proposed the implementation of a series of projects based on the following reduction concepts:

• Rearrangement of drains in order to avoid non-active fluids entering the waste treatment system.
• Replacement of the water for spent resins conditioning by evaporator concentrates, thus reducing the generation of concentrate packages.
• Segregation and minimization of wastes coming from the replacement of steam generators from PWR's systems.

Additionally, the selection criteria to implement the proposed projects in this first phase were based on the percentages of every waste streams in the total LILW generation. Fig 3 shows the annual average percentages.

The 1995 Global Action Plan, considered as a first phase of the volume reduction program, was mainly focused on simple projects with no major uncertainties in their results. The cost of all the projects rose up to 100 Mpts ($700,000), which resulted in a one time reduction of 1,400 packages and a periodic decrease of 150 packages per year.

The LILW generated by all the Spanish NPP's in 1997 were 4,519 packages, which represented an additional reduction of about 10% with regard to the generation of 1994, a year before the implementation of the Plan. See Table IV.

At present, and after completion of the projects of the first phase, a second phase has been launched, where Nuclear Power Plants have put forward more than thirty proposals.

The ranking criteria in this second phase, besides the cost-benefit analysis, to implement the proposed projects has been also based on the percentages of every waste streams in the total LILW generation. Figure 4 shows the annual average composition and the volume reduction obtained since 1994.

The reduction concepts considered in these proposals are grouped as follows

• Segregation of compactible waste.
• Decontamination and exemption of oils.
• Decontamination of woods.
• Rearrangement of drains (Supplementing Phase 1).
• Exemption of "very low level" packages.

• Drying of concentrates and sludge by fixed or mobile facilities.
• Adding up of concentrates and sludge in resin packages (Supplementing Phase 1).
• Sludge filtering and drying.

• Increased concentration of boron in the evaporator.
• Waste reduction in steam generator (SG) replacement (Supplementing Phase 1).
• Improvements in the condensate purification system.
• Decontamination of SG's blowdown resins.
• Segregation of non-compactible waste.

• Increased dosage of resins per package.
• Reconditioning of microcell packages by means of drying.

The required investments for all the projects together in this second phase will be of about 1,070 Mpts ($7.6 millions) and estimates pointed to an initial reduction of 5,700 packages and, additionally, a reduction in annual generation of around 1,250 packages for all the NPP's.

It is expected to implement all the projects of this Action Plan by the year 2001. Table V shows the expected LILW generation according to the implementation of those projects planned in this second phase.

Once the projects had been implemented, it is expected to reduce the annual LILW generation of Spanish NPP's to about 3,000 packages (660 m³), in other words, a reduction of more than 50% of the 1990 generation levels.

The agreement between the NPP's and ENRESA has permitted to develop investment projects at the Spanish plants with the main goal of reducing the LILW generated, demonstrating as well to be a useful tool.

Besides all those projects, NPP's will continue developing good operational practices to reduce the waste generated as much as available. Currently, the main criteria to take into account to reach those objectives are as follows:

• Full segregation of radioactive and non radioactive streams to avoid any clean material in the radwaste systems.
• Decontamination of solids followed by an exemption process of those materials to reduce the final volume of radioactive wastes to be managed.
• To develop and follow a safety-quality culture for the radioactive waste management in the NPP's.

The last criteria is considered the keypoint to go further on improving the management of radioactive systems in the Spanish NPP's.

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