7 INFORMACION SOBRE EL EMISOR
7.2 Directores y Ejecutivos
The final product is a granulate cast iron which could be manufactured from radioactive steel arising from the decommissioning of Spanish nuclear installations. The manufactured granulate is used instead of sand (total or partially) in cement mortar which is used for infilling and immobilisation of wastes in drums. In addition the production of metallic fibre is also considered as a final product here. However in this case the fibre is placed between drums in the disposal container and is incorporated into the cement matrix when the containers are infilled with grout.
Quantity of Carbon Steel Required and Arisings of Suitable Material
The grout used at the El Cabril disposal facility has a composition of 175 kg of sand for each 100 kg of cement. The increased weight from the substitution of granulate for sand is negligible. In each container approximately 4550 kg of mixture dry cement-sand is used of which 2800 kg is sand. If 50% of the sand is substituted by steel granulate 3800 kg of metal per container would be required. The total sand substitution by granulate would then be 7600 kg per container. Currently between 440 and 500 containers per year are used at the El Cabril disposal facility and therefore about 1670 tons of granulate could be used per year assuming a utilisation of 50% of sand and 50% of granulate.
Estimates of the quantities of radioactive scrap arising from the nuclear Spanish installations suggest that from year 2000 onwards more than 20,000 t of carbon steel scrap would be available. This quantity is sufficient to supply a recycling plant with material for 10 years.
Process Steps for Scenario 6
The main activities of this scenario are the following:
• Segmentation scrap for transport.
• Transport and monitoring of radioactive material.
• Reception, sorting and storage in the melting plant.
• Preparation of scrap for melting.
• Loading of furnace and melting.
• Granulate / fibre production from molten metal.
• Storage and characterisation of granulate / fibre.
• Conditioning and transporting granulate / fibre and secondary wastes to disposal site.
• Preparation dry mixed sand - granulate
• Incorporation of mixed cement mortar in container and disposal.
Since there is not enough scrap to justify an on site recycling installation, it has been assumed that the melting and manufacturing plant will be integrated as a specific installation of an existing conventional melting/casting plant or as an independent melting, casting and
Besides the equipment and installations of a commercial melting or casting plant, some ancillary areas or systems are also required inside the recycling plant, eg storage and handling areas for radioactive scrap, occasional cutting equipment in order to fit the size scrap to capability of furnace, radiological protection system, special ventilation and filter systems, monitoring, radiological characterisation, etc. The scrap arriving to the plant, inside transport containers, must be temporary stored on site in order to fit the planned melting campaign.
The nominal capacity of the plant could be of 2000-3000 t per year and the furnace would be electric induction type of 4.5 t capacity. The auxiliary equipment required for granulate and fibre production is relatively simple including a tank and pump.
The general acceptance criteria for metal melting in the plant are assumed to be the following (based on discussions with plant operators and available literature) :
Radiation levels:
Radiation level per package <0.1 mSv/hr contact (1 cm)
Surface contamination or activated metal <0.1 mSv/hr average contact (unshielded) Radionuclide limits:
In general terms the average radionuclide concentration shall not exceed the 1500 Bq/g for Co-60 or gamma - beta emitters and 100 Bq/g for alpha emitters over the package or component. There will also be a list of radionuclides with the upper activity limit defined for each of them, although details of this list are not considered here.
The dose rate calculation for this granulate/ fibres scenario should be developed according to the IAEA models based on a maximum of 200 Bq/g in the final product. Appendix 3 presented estimated doses to workers for the production of fibres and granulates based on the IAEA dose model.
Technical Details of Scenario 6
The granulate is formed by particles of spheroid shape that are obtained through the pouring of molten metal onto a cold water jet. The size or diameter of granulate can be easily adjusted to meet the needs of the application during the manufacture process. Its size or diameter depends fundamentally on the flow of molten metal provided and on the pressure and flow of water jet which falls onto the metal. These data can be regulated in each installation to obtain the desired product.
The metallic fibre is obtained by pouring molten metal on a refrigerated cylinder that turns at speed. The dimension of the fibre (length, thickness, etc) can be adjusted for a given flow of molten metal by the refrigeration temperature, the speed of the cylinder and the temperature of the molten metal.
The specification of scrap used for the production of fibres and granulate is very low especially for granulate. There are no stringent requirements on chemical composition, impurities, resistance, elasticity, etc for the final products.
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Due to their application, the particles of the shot are not subject to specific specifications with regard to their size, shape, hardness, surface state, etc. The production process to obtain the shot of smelted steel from the scrap steel or its corresponding ingot is as follows:
• The smelting of the scrap or the ingot.
• The adjustment of the composition and killing.
• The transporting of the molten steel to the smelting ladle.
• The running off of the steel from the ladle via water blasting which produces the granulation of the molten steel and the solidifying of the granules.
• The drying of the granules and classification. The following equipment is required:
• A smelting furnace.
• A smelting ladle.
• A water circuit with its corresponding nozzles to produce the water blasting.
Given that the basic technical equipment for this production line is the same as, or similar to, that of smelting and casting (smelting furnace and ladle) this can be used without the need for any significant additional investment.
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The manufacturing process suggested for these fibres would be a smelting and rapid setting process of steel smelted in an appropriate cast rotating at high speed.
The manufactured fibres would have a length of between 25 and 35 mm and would be ideal for reinforcing concrete. They can be manufactured to a thickness of between 0·025 and 1·25 mm. The sizes of the fibres mean that they are easy to handle and may be rapidly dispersed in the concrete during mixing. The addition of the fibres enhances the properties of the concrete. They help to prevent the formation of cracks and they act as a reinforcement, which gives the concrete significantly enhanced properties.
The manufacturing process for fibre which is to be used as a construction reinforcement would be a continuous smelting and rapid setting process which avoids the need for subsequent rolling processes for obtaining the final product. The manufacturing process would basically be as follows: An induction furnace for smelting the base material. An accumulator and dosifier with a valve for controlling the flow of smelted material which has to fall onto the setting cast. The setting wheel which houses the cast which has the form required to produce the product. A control unit for adjusting the size of the bands or threads produced. Finally, the cutting line or coil winder and the stores for the finished product. The
cost of an installation of this kind, for small production, would be in the order of some 90 million pesetas
Economic Assessment of Scenario 6
In this section a comparative economic examination is analysed between direct disposal of metallic scrap and the alternative of recycling by means of granulate. The associated cost involved in the recycling option include :
• Cutting and packaging (20 feet ISO containers) of the arising scrap.
• Scrap transportation.
• Investment in a radiological metal recycling installation.
• Operating the metal recycling installation including storage, sorting and melting
• Granulate / fibres and secondary wastes transportation.
• Preparation dry mixed sand - granulated - cement.
• Incorporation of cement mortar to container and disposal
*UDQXODWHPDQXIDFWXULQJFRVW(assuming production of 2,000 t per annum)
PROJECT COST
Engineering 1 Million pts £5,000 7.2 kECU
Civil Works additional equipment above that for melting/casting is not required
Equipment 12 Million pts £60,000 86 k ECU
Tests 1 Million pts £5,000 7.21 kECU
Radiological Protection 4 Million pts £20,000 29 kECU
Control 2 Million pts £10,000 14 kECU
TOTAL 20 Million pts £100,000 143 kECU
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OPERATION
Workers 10.0 Million pts/year £50,000 / year 72 kECU/yr
Technicians 6.0 Million pts/year £30,000 / year 43 kECU/yr
TOTAL 16.0 Million pts /year £80,000 / year 115 kECU/yr
6SHFLILFFRVW SWVNJ W (&8W
OVERHEAD EXPENSES
8.0 Mill ion pts/year or £40,000 /year or 57 kECU
6SHFLILFFRVW SWVNJ W (&8W
DISMANTLING
20.0 Million pts or £100,000 or 143 kECU
6SHFLILFFRVW SWVNJ W (&8W
OTHERS
2.0 Mill ion pts / year or £10,000 / year or 14.3 kECU
6SHFLILFFRVW SWVNJ W (&8W
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7.6 t of scrap = 7.6 t of granulate and 280 kg secondary wastes ( 2 drums ) Dismantling activities 430 ECU/t
Melting 860 ECU/t Manufacture of Granulate 107.5 ECU/t
Preparation of mix 72 ECU/t
Transport 287 ECU/t
TOTAL 1756 ECU/t
Conditioning 1790 ECU/ box
Granulate 13345 ECU
Secondary wastes disposal 3584 ECU
Drums 1084 ECU
TOTAL 18010 ECU
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PROJECT COST
Engineering 5 Million pts £25,000 36 kECU
Civil Works no further equipment required
Equipment 90 Million pts £450,000 645 kECU
Tests 5 Million pts £25,000 36 kECU
Radiological Protection 10 Million pts £50,000 72 kECU
Control 10 Million pts £50,000 72 kECU
TOTAL 120 Million pts £600,000 860 kECU
6SHFLILFFRVW SWVNJ W (&8W
OPERATION
Workers 10.0 Million pts/year £50,000 / year 72 kECU/yr
Technicians 6.0 Million pts/year £30,000 / year 43 kECU/yr
TOTAL 16.0 Million pts /year £80,000 / year 115 kECU/yr
6SHFLILFFRVW SWVNJ W (&8W
OVERHEAD EXPENSES
8.0 Mill ion pts/ year or £40,000 or 57 kECU
6SHFLILFFRVW SWVNJ W (&8W
DISMANTLING
20.0 Million pts or £100,000 or 143 kECU
6SHFLILFFRVW SWVNJ W (&8W
OTHERS
2.0 Mill ion pts / year or £10,000 / year or 14.3 kECU/yr
6SHFLILFFRVW SWVNJ W (&8W
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7.6 t of scrap = 7.6 t of fibre and 280 kg secondary wastes (2 drums) Dismantling activities 430 ECU/t
Melting 860 ECU/t
Manufacture of fibre 143 ECU/t
Preparation of mix 72 ECU/t
Granulate 13617 ECU Secondary wastes disposal 3583 ECU
Drums 1084 ECU
TOTAL 18284 ECU
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Re-evaluation of Scenario 6 with Common Cost Assumptions
The costs for each of the main stages in the scenario are summarised here using two disposal charges - one typical of a near surface disposal facility and another typical of a deep
geological repository. The cost analysis below includes common assumptions relating to transport costs and scrap handling charges. The calculation of disposal costs for secondary waste and for the disposal option includes minimal volume reduction prior to disposal. Supercompaction of some wastes may be carried out but calculations have assumed a packing density of 1.2 t/m3 for secondary wastes from processing and 1.5 t/m3 for direct disposal of wastes.
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Capital cost of plant 1,985,000 / 2,702,000
Operating costs of plant (per year) 2,840,000
Decommissioning costs of plant 1,505,000
Costs of containers for disposal of secondary wastes (drums) 60 Costs of containers for disposal of secondary waste (concrete) 3585 Total disposal charge for secondary waste (shallow) 4,845,000 Total disposal charge for secondary waste (deep) 131,869,000 Costs for handling of wastes/scrap and transport (715 ECU/t) 11,969,000 TOTAL (shallow) 48,700,000 / 49,416,000
TOTAL (deep) 175,724,000 / 176,441,000
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Cost of buying final product (each) 0
Costs of containers for disposal of wastes (drums) 60 Cost of containers for disposal of wastes (concrete) 3,585 Costs for handling of wastes/scrap and transport (575 ECU/t) 9,575,000
TOTAL (shallow) 31,629,000
TOTAL (deep) 609,777,000
Cost of recycling - disposal (shallow disposal) 17,071,000 / 17,788,000 Cost of recycling - disposal (deep disposal) -434,053,000 / -433,336,000 Scenario 6 - Conclusions
The economic assessment using Spanish costs indicates that the costs of production of fibres and granulate are roughly equal with fibre production being slightly higher than that of granulate. Both options have been shown to be considerably cheaper than the alternative option of disposal of the scrap in a near surface type repository. The scenario has been re- evaluated with two disposal charges to assess the sensitivity of the economic to increase in
disposal charges and with a common approach to scrap handling charges and transportation charges to allow scenarios to be directly compared. This indicates that an increase in ear surface disposal charges may be required in order for the scenario to be economically attractive. Costs are strongly dependent on the assumptions made relating to packaging densities in waste containers ie whether supercompaction of secondary wastes or wastes for direct disposal is carried out will have an important effect on the costs assumed for recycling and disposal.