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DECOMMISSIONING OF THE JEN-1 EXPERIMENTAL REACTOR

Objective

JEN-1 is an experimental reactor of the swimming-pool type, moderated and cooled by light water, with a power of 3 MWt. It was operated from 1958 till 1984 with a total generated energy of 2,700 MWd. The radioactive inventory is estimated in the order of 3.5E11 Bq (9.5 Ci), the dose rates are estimated in the range of 20 to 150 mGy/h.

The main aim of this project is the study and development of decontamination, cutting and melting techniques on contaminated or neutron-activated aluminium components of JEN-1.

Underwater segmenting of aluminium components still represents some problems to be solved, which consist especially in the limited visibility of the cutting environment, due to an important amount of very small suspended articles (10%, compared to steel 1%) and in the difficult filtration of these particles. An important aspect relevant to safety is the high H2 generation rate due to a rather long lasting reaction of molten aluminium particles with the surrounding water.

Industrial-scale melting of aluminium components still needs development work for appropriate foundry techniques, especially concerning crucible material and slag formation.

Results obtained in this contract will be useful in the future for the dismantling of numerous research reactors with aluminium components.

The project is expected to produce specific data on costs, working time, waste arisings and radiation exposures to operators for the dismantling of the JEN-1 reactor.

After the second call for proposals in Section C a follow-up contract was concluded for the dismantling of further components: the primary circuit coolant collector and the support structures of the ionization chamber. Work in contract FI2D0023 was limited to following components: core grid, support grid and control blade housing. Work in the second contract will need an adaptation of techniques and procedures already developed in the first work-programme for components having now larger wall thicknesses and different geometric configurations.

The work programme will be implemented in co-operation between following Spanish organisations: CIEMAT, ENRESA, ENSA and LAINSA, and with Institut fur Werkstoffkunde of Universitaet Hannover (UH/IW), CIEMAT being the coordinator. A cooperation on aluminium melting will be installed with Siemens AG KWU Group and Siempelkamp Giesserei Krefeld (SG).
The main aim of this project is the study and development of decontamination, cutting and melting techniques on contaminated or neutron activated materials using some components of the JEN-1 reactor. 40 spent fuel elements have been taken out from the reactor pool. The first activities of dismounting and radiological characterization of components from the JEN-1 reactor core have started.

In parallel with these operations, work went on in the following areas:
design and manufacture of an underwater cutting facility;
cutting tests with a plasma torch and a consumable electrode tool;
coagulation tests to find a suitable electrolyte for the precipitation of aluminium oxide particles in water;
decontamination tests;
design and construction of a facility for melting aluminium;
dismantling of reactor core components.
WORK PROGRAMME

1. Radiological characterization of components to be dismantled, and of melting products (CIEMAT)

1.1. Radiological characterization of the grid and support grid.
1.2. Radiological characterization of the control blade housings.
1.3. Radiological characterization of the primary coolant circuit collector.
1.4. Radiological characterization of the support structure for ionization chambers.
1.5. Radiological characterization of the melting products.

2. Development, manufacturing, testing and subsequent installation in the JEN-1 reactor of an underwater cutting facility by plasma arc and by consumable electrode techniques (UH-IW, CIEMAT).

2.1. Development and manufacturing of prototypes of plasma arc torch and consumable electrode torch (UH-IW)
2.2. Cutting tests with both tools on representative aluminium sheets, aiming at defining optimal working parameters, cutting effluents and appropriate air and water filters (UH-IW, CIEMAT)
2.3. Comparison of both tests with respect to cutting performance, generation and type of cutting effluents and tool handling abilities with subsequent selection of the most appropriate tool (CIEMAT + UH-IW)
2.4. Design and manufacturing of a cutting facility, including the selected cutting tool, handling and sensor systems and the cutting cell (UH-IW)
2.5. Testing at UH-IW and optimization of the whole system in water depths of 5 m (UH-IW, CIEMAT)
2.6. Training of the CIEMAT staff at UH-IW (UH-IW + CIEMAT)
2.7. Transport and assistance for the installation of the cutting facility in the JEN-1 reactor (UH-IW)

3. Underwater dismantling of reactor internals after preceding dismounting work (CIEMAT + UH-IW)

3.1. Dismantling of the grid and grid support
3.2. Dismantling of the control blade housings
3.3. Dismantling of the primary circuit cooling collector
3.4. Dismantling of the support structure for ionization chambers

4. Decontamination of reactor internals (ENSA, LAINSA).

4.1. Selection of suitable procedures with respect to decontamination efficiency, amount and type of arising secondary wastes, reprocessing abilities and radiological impact
4.2. Decontamination of the grid and grid support
4.3. Decontamination of the control blade housings.
4.4. Decontamination of the primary circuit coolant collector

5. Melting of aluminium waste (CIEMAT, ENRESA)

5.1. Selection, manufacturing and adaptation of a melting furnace and implementation of cold melting tests.
5.2. Main melting programme, including generation of data on volume reduction and decontamination effects.

6. Assessment of radiation protection including both the personal and the ambient radiological impact (CIEMAT, UH-IW)

6.1. Assessment of radiological impact during dismantling operations (CIEMAT, UH-IW)
6.2. Assessment of radiological impact during decontamination operations (CIEMAT)
6.3. Assessment of radiological impact during melting operations (CIEMAT)

7. Generation of specific data on costs, radioactive job doses, working time and secondary waste arisings, derived from the execution of items 3, 4, 5 and 6.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

CENTRO DE INVESTIGACIONES ENERGETICAS, MEDIAMBIENTALES Y TECNOLOGICAS
Address
22,Avenida Complutense 22
28040 Madrid
Spain

Participants (4)

EMPRESA NACIONAL DE RESIDUOS RADIOACTIVOS S.A.
Spain
Address
7,Emilio Vargas 7
28043 Madrid
Equipos Nucleares SA
Spain
Address

28006 Madrid
Logística y Acondicionamientos Industriales SA
Spain
Address
13,El Palleter
46008 Valencia
UNIVERSITAET HANNOVER
Germany
Address
Welfengarten 1 B
30167 Hannover