EISS - CADARACHE

Technical Aspects

Cadarache satisfies all ITER site requirements

The design assumptions are satisfied, most of them with a comfortable margin, with two minor exceptions:

• the seismic level is slightly higher in Cadarache than on the generic site
• the capability of the network to supply reactive power is lower than on the generic site

No technical difficulty is anticipated and the extra cost with respects to these issues is limited.
Two different routes for the transportation of large and heavy components have been fully assessed.

Overview of CEA Cadarache

Cadarache, established in 1959, covers 1600 hectares and is the largest research centre of the French Atomic Energy Commission (CEA). It is located at the very heart of historical Provence, halfway between Aix-en-Provence and Manosque.

Figure 1:ITER location on the Cadarache site

Cadarache is the main CEA centre for power oriented nuclear research, with experimental reactors, specialised laboratories and workshops for a total of 18 nuclear facilities. The centre provides employment for 5 000 people and it has an annual budget of 400 M€. The EURATOM-CEA Association, which coordinates the French activity on magnetic thermonuclear fusion, is also based on the Cadarache site and it operates the superconducting tokamak Tore Supra since 1988. In addition to several specialised laboratories and reactors, a number of general services are available on the Cadarache site, e.g. local security and radiation protection.
The Cadarache research centre has all the necessary infrastructure to host a nuclear facility such as ITER.

ITER site layout

Figure 2:Detailed layout of the buildings

Following the assessment of 3 specific areas, it is proposed to locate ITER at the Northeast boundary of the Cadarache site (Figure above). The layout of the buildings is in accordance with the generic site drawings, except for the cooling towers, which have been repositioned 300 m away according to the dominant winds. The office building has been rotated to improve access (Figure on the right). Additional buildings and services (restaurant, medical service, etc.) are also indicated.

Test drillings were carried out to determine the location of the limestone substrate, which was found to be of good quality and at a maximum depth of about 10 m. A more detailed geological investigation is underway to finalise the exact location of all buildings and to determine the soil characteristics necessary for the detailed design of the foundations.
Architectural studies intended to estimate the visual impact were made. The figure below gives a preliminary outline of the site with the ITER buildings.

Figure 3:Insertion of ITER in the Landscape

Seismic aspects

The ITER JCT has designed the safety-classified buildings in accordance with the ASME and the US NRC guidelines. The results should be valid for a wide range of sites with the exclusion of those with unusually soft soils. The primary scaling parameter used is the maximum ground acceleration, assumed to be 0.2 g for the generic ITER site. At Cadarache, the "Règles Fondamentales de Sûreté" require to consider the so-called "Séisme Majoré de Sécurité" (magnitude of 5.8, epicentre at 7.1 km) and the "Paléoséisme" (magnitude of 7, epicentre at 18 km), whose maximum ground acceleration are, respectively, 0.315 g and 0.281 g.
Stress analysis shows that the Tokamak Building, as it is now designed, is able to withstand the Cadarache seismic conditions without any major reinforcement. About 150 eigenmodes have been calculated in each of the three directions and the main modes in the horizontal directions were found in the range 3.6 – 3.7 Hz. A few weak points have been identified at the level where the superstructure is connected to the upper slab. Floor spectra have also been computed in order to assess the design of the safety related equipment inside the tokamak building (this assessment has not yet been done for the generic site).
As an alternative, the use of 400 paraseismic bearings for the ITER tokamak building has been assessed. These bearings, made with elastomer foils interleaved with stainless steel plates, are commonly used for bridge supports and in some nuclear buildings. Their use leads to a decrease in the overall acceleration on the building, and consequently on the equipment, to 0.1 g. This would result in significant savings for the building and all inner equipment but, on the other hand, an overall displacement of the building of roughly 75 mm (without bearings, the displacement is a few mm a ground level and 52 mm at the superstructure level) is foreseen at a frequency of 0.56 Hz. The interfaces with nearby buildings will need to be checked carefully because of this motion.
The two options (local reinforcement of the building and the use of paraseismic bearings) are feasible. No major modification with respect to the generic design is foreseen.

Heat sink and water supply

A consumption of 1.5 million m3 per year has been estimated for the cooling water circuits. This is equivalent to the present total consumption of the Cadarache centre. It will therefore be necessary to install a new system. The preferred solution is to supply water by means of gravity from the EDF canal of Vinon-sur-Verdon. The investment cost for this solution is slightly higher than for other alternatives, but this is offset by the reduced cost of operation since no pumping station is required. Other new installations are foreseen at Cadarache and will also require modifications of the water supply; synergies might be obtained between the different projects.
The climate in Cadarache, warm but very dry in the summer, allows the overall dimensions of the cooling towers to be reduced, the wet bulb temperature in Cadarache being 24°C instead of 29°C as assumed by ITER. However, the relocation of the cooling towers leads to an increase in the length of pipe work by 300 m (2 pipes of 2 m diameter).
About two thirds of the water evaporates in the cooling towers. The rest will be discharged into the Durance River or the canal, after the necessary controls, making use of the current discharge outlet of the Cadarache site.

Figure 4:Proposed ITER High Voltage Supply
Scheme

Electrical Power Supply

The electrical network around Cadarache is well equipped with many lines and two powerful nodes, Boutre (5 km east of the ITER site, with an interconnection at the 400 kV/225 kV level through an autotransformer) and Sainte-Tulle (8 km north of the ITER site, with an interconnection at the 225 kV/63 kV level). Moreover, Tore Supra is already supplied by a 400 kV dedicated line and the Cadarache centre by two 63 kV lines.
The generic ITER design is based on a single 400 kV line and a double 225 kV line. Several alternatives have been considered and compared by the public company RTE. In particular, the environmental impact has been considered very carefully taking into account the visual impact of 225 kV and 400 kV pylons. The reference scheme is shown in the figure on the left. All modifications necessary take place on CEA property.
The design assumptions for the reactive power compensation are not satisfied. The ITER static VAR compensator will have to be increased from 540 Mvar to 660 Mvar and driven as voltage regulator to reduce the voltage drop on the network within acceptable limits. This design modification will have a modest impact because there are margins in the present design. On the other hand, the design assumptions with respect to the active power are widely exceeded and 1000 MW could be delivered for 30 s instead of the assumed 500 MW. Should this point be confirmed, a scheme with only a double 400 kV line could be proposed, leading to cost savings on both site adaptation and generic design. This scheme is fully compatible with the ITER site requirements and design assumptions.

Transport of heavy and large components

The transport of large and heavy components to Cadarache, which is located 70 km from the nearest sea harbour, has required specific studies. A careful review of all dimensions and weights of these components has been made in close collaboration with the ITER JCT and the weight and size of the handling and protection equipment have been estimated.

The public agency "Centre d´Études Techniques de l´Équipement" (CETE) has evaluated two routes

• in a first instance, the use of an already existing itinerary for "convoi exceptionnnel" between Fos-sur-Mer (Marseille) and Cadarache. Certain sections would require technical adaptations, in particular roundabouts and bridges, but no administrative difficulty is anticipated. This first scheme requires the use of a section of EDF canal (see below).
• in a second instance, an alternative route, only by road has been assessed. It has the advantage to be faster: 3 days, compared to 10 days (no load transfers to and from the barges), but would require more technical adaptations

In addition, the "Centre d´Ing&eacut;nierie Hydraulique d´EDF" analysed the transportation on the Durance EDF canal by means of ad-hoc barges. One hydroelectric power station would be by-passed via a specifically constructed track. The use of about 40 km of the canal requires, besides the manufacture of the barges, the modification of a few bridges and the construction of specific handling equipment for loading and unloading the components on the barges. The figure below illustrates the two possible routes.

Figure 5:Reference routes (by road only, or combination of road and canal), from Fos harbour to Cadarache