The marine discharge pipe at AREVA La Hague

The work has been carried out in compliance with environmental measures set by the Nuclear Safety Authority for the facility. These measures have a double objective:

• Implementation of means ensuring the risk of spreading radioactive materials into the environment is prevented. Work is carried out in respect of preventative measures against risk of spread of radioactive materials into the environment associated with an alert threshold of 1 Bq/g and a stop threshold of 10 Bq/g. Aside from some rare local events preceding the work, all results of the sampling carried out as part of the specific environmental monitoring program were below 1 Bq/g, which corresponds to the natural radioactivity of a block of granite. These radioactivity measurements show that the worksite environment has not been affected by the work.

• Guarantee freedom from radiological impact for the population and living species.

Three stages of work

The work, divided into three phases, consist of:

• Terracing, in other words clearing the terrain using heavy digging equipment, in particular a walking excavator in order to terrace the steepest part of the cliff.
• Demolition of the concrete covering the pipe: a cable car then be put in place on the side of the cliff to allow access to the worksite and removal of rubble.
• Shifting the pipe: the pipe will have to be lifted, in its current form, to a work pit, where it is cut into pieces and then packaged.

One requirement: rerouting of the Custom Officers Route

The profile of this section of pipe intersects with the Custom Officers Route for which there is a right of way. A new layout has therefore been temporarily arranged, a little further to the north, to allow the work at the top of the cliff. The new path has been open since October 30, 2002.

An example of successful integration

The new path is constructed entirely of specially treated wood. This choice responds to the willingness to integrate the work into its environment and to a demand for durability against the elements. This new path was maintained for about one year. The original layout was restored once the work is completed.

A worksite under a controlled and organized environment

This project was authorized by the Nuclear Safety Authority in September 2002. It is part of the same program of environmental monitoring as that led for the first project. The following steps were therefore taken:

• Measurements of contamination from demolition residue.
• Radiation measurements of the disassembled pieces.

At the same time, during the disassembly work, the Special and Permanent Information Commission for the Facility at La Hague (CSPI) has entrusted a radiological monitoring assignment for Anse des Moulinets to the Association for Radioactivity Monitoring in the West (ACRO).

1. Phasing of work that has taken consideration of the difficulties specific to each zone. As such the most difficult stages were carried out last, in order to benefit from feedback.

• Carrying out work outside the public maritime domain: disassembly of the pipe located at the top of the cliff.
• Carrying out work in a tidal zone in the summer in order to take advantage of optimal ocean and meteorological conditions.
• Addressing the section located along the cliff, making it necessary to first divert the Customs Officers Route.
• Addressing the section where the pipe passes under the ramp. This required partial demolition of the ramp.

2. Coordination of the different parties involved, manifest notably through a weekly follow-up of the operations both underway and upcoming.

3. Analysis of potential risks to the environment in order to prepare adaptive standby measures in the event that the separation barriers break down during work.

4. Qualification of operating methods and training of involved parties on a scale model before any operation.

5. Routine communication with the media and elected officials on the forecasts and progress of the work.

During the work, 5,000 samples and analyses have been carried out. The following are carried out on an ongoing basis:

• A daily analysis of seawater from Anse des Moulinets.
• A quarterly analysis of algae, limpets and sand from Anse.

Throughout the entire work period:

• Measurements of contamination from demolition residue.
• Radiation measurements of the disassembled pieces.
• Weekly analyses of the sand at low tide.

Following these analyses and measures, no environmental impact has been observed.

At the same time, during the work, the Special and Permanent Information Commission for the Facility at La Hague (CSPI) has entrusted a radiological monitoring assignment for Anse des Moulinets to the Association for Radioactivity Monitoring in the West (ACRO).

• Project cost: 20 million Euros.
• Man hours:  80,000 productive hours.
• Earth moving and demolition: 1,300 m3 of rubble.

Operational dosimetry report: the report is less than 34% of what was anticipated. This positive outcome was obtained thanks to the optimization of operations and to the incorporation- and feedback of experience between the various stages.

Packing: waste was packed on-site, following procedures used in the facility, based on their destination: metal drums, metal boxes and cubic fiber concrete containers (CBFK)

All of this low-level radioactive waste is sent to the surface waste storage facility of ANDRA in Soulaines, in the regional department of Aube, France.

• Mid 1960s: construction of the old marine discharge pipe, used until 1980.
• From 1983 to 1985: disassembly of the submerged section of the first pipe.
• April 2002: start-up following authorization from the Nuclear Safety Authority, of work on the disassembly of the section of the pipe located in the tidal zone.
• August 2002: end of disassembly of the two pipe sections, the first located near the Custom Officers Route at the top of the cliff and the second in a tidal zone.
• September 2002: authorization acquired to carry out the disassembly work on the part of the old pipe located between the AREVA fence and the cliff.
• October 2002: rerouting of the Custom Officers Route.
• May 2003: end of disassembly of the section located along the cliff and authorization acquired to carry out the disassembly work on the last section, situated between the cliff and the ocean access ramp.
• July 2003: start of work on the final section.
• August 2003: restoration of the original layout of the Customs Officers Route.
• December 2003: end of disassembly of the final section.
• March 2004: restoration of the tidal zone worksite breakdown.