In 1970 the French government chose Pressurised Water Reactor technology for its civil nuclear park and as a consequence stopped the development of Gas Cooled Reactor technologies.
For this reason Brennilis Nuclear Power Station, a 250 MWt heavy water moderated reactor was shut down in 1985 after 18 years of commercial operation. Decommissioning of the station started shortly afterwards with the removal and evacuation of the fuel, solid waste and liquid effluent.

In 1995 the Government gave the go-ahead to complete Level 3 (Stage 3 following the IAEA guidance) decommissioning of all buildings and facilities on the site with the exception of the reactor building.
Two consortiums were awarded work worth a total of 200 million French Francs. Nuclear management was awarded to a Framatome-Anp-Anp led consortium and the dismantling operations to another consortium. The overall project management was led by EDF. The project commenced in 1996 and is expected to finish in 1999.

Framatome-Anp associated with its subsidiary STMI undertake radiological survey and waste inventory of the facilities to be dismantled, the design, supply and operation of waste characterisation facilities, the supply of waste containers as well as health physics monitoring of the 150 site personnel involved.

The project consists of 4 distinct phases :

1. Design studies 1996

A complete radiological survey was performed consisting of 5000 contamination and radiation measurements including cored samples to determine an activity spectrum for each building.
This data was used to establish an overall expected waste inventory to determine the dismantling methodology, the type and number of waste containers required as well as the design of radiological measurement facilities for waste packages of varying geometry.
Some 150 m³ of contaminated concrete and 3,200 tonnes of metallic waste will have to be packaged in 7,000 X 200 litre drums, 150 X 5 m³ containers, 450 X 7 m³ containers as well as 350 twenty foot containers.
The activity range of the waste is 1 Bq/g to a few MBq/g. A further 13,000 m³ of uncontaminated concrete will be used to backfill the site.


2. Supply and commissioning 1997

Two waste package characterisation systems for 200 litre drums and a system for 5 m³ and 7 m³ containers have been designed, supplied and commissioned. Waste package activities are calculated from dose rate measurements. The drum systems have a throughput of 16 drums/day whereas the container system has a throughput of 6 containers/day.
A computer network system has been installed which collects all data and provides complete tracability of the waste packages in real time through the use of code bar labelling.
Health physics management of the personnel is performed by a computer network system which has also been commissioned. This system closely follows the personnel dose up-take task by task, building by building and for the whole site, and comparing the results with strict ALARA based previsions, enables interventions to be controlled or adapted accordingly.
As part of the system a large range of personal and general surveillance health physics equipment has been set-up on site.


3. Dismantling operations 1997 - 2003

Dismantling operations are newly underway and Framatome-Anp will ensure the provision of all waste packages, operation of the waste characterisation equipment and management of the waste, health physics monitoring of all personnel and management of dose up-take.


4. Preparation for Level 3 decommissioning of the reactor building 1999

Framatome-Anp will design, supply and commission an automatic health physics monitoring and surveillance system for care and maintenance of the reactor building.
This new system which will replace an existing out-dated system and once installed will enable personnel to follow the radiological evolution of every room within the building without having to intervene.
A comprehensive radiological data base of the building will be created over time to enable preparations for Level 3 dismantling work to begin.