Since 1986, Framatome-Anp has built up a wealth of experience and engineering expertise in the field of chemical decontamination and chemical cleaning through both long term R&D activities as well as the industrial application of patented processes to assist Nuclear Power Plant maintenance and decommissioning operations around the world. Currently this activity is managed by specialised teams located in France and the USA.

Framatome-Anp apply chemical decontamination techniques to steel and steel alloy primary components and circuits which are heavily contaminated with the aim of reducing the residual radioactivity levels to ones which enable easier interventions to be made or which enable a decommissioned component to meet local waste disposal or free release requirements.
Generally the techniques involve circulating an acidic or basic solution (more or less strong), over a period of time (more or less long), through the component or circuit, to dissolve the contaminated surface layers which have built up while in service. The operation is finally completed by rinsing. The resulting radioactive chemical effluent should be simple to treat with the resulting waste product reduced in volume and able to meet waste disposal criteria. For a given application, the chosen process should also provide overall savings in terms of radiological exposure time to operators and waste disposal costs.

Chemical cleaning techniques are applied to steel secondary circuits and components to remove rust and deposits which have built-up through plant operation as a means of recovering plant performance.
To meet these objectives, Framatome-Anp has used the best available chemical decontamination and chemical cleaning processes available on the market at the time :

The chemical decontamination process MEDOC (MEtal Decontamination by Oxidation with Cerium), is based on the use of cerium IV as strong oxidant in sulphuric acid with continuous regeneration using ozone.
An industrial installation has been designed and constructed at SCK·CEN in Belgium to treat metallic pieces arising from the dismantling of the BR3 PWR reactor.
The industrial scale MEDOC plant allows the batchwise treatment of 0.5 tonne/day of highly contaminated materials e.g. up to 20,000 Bq/cm² and can achieve decontamination factors higher than 10⁴.
Since the installation starts up in september 1999, 80 % of the treated material including primary pipes has been cleared and sold to a scrap dealer. Up to now, MEDOC has been accomplished as a batch process, the SCK·CEN use now the MEDOC plant to decontaminate large components in one piece before cutting them, such as the BR3-steam generator and the pressurizer. The purpose of this operation is to reach sufficient decontamination factor to reduce the dose rate and free release material after melting.
More info on Medoc.

In 1986, Framatome-Anp performed the decontamination of two primary water recirculation lines before their removal at Muhleberg NPP (320 MWe BWR), in Switzerland using AECL's CAN-DECON process.
Framatome-Anp supplied and operated the decontamination equipment which consisted of two skid mounted units and a laboratory container. These were installed in a building outside of the radiologically controlled area and connected to the recirculation lines by flexible hoses.
The operation took 3 days to complete and reduced the ambient dose rate from 10,000 to 500 mSv/h resulting in savings of 2 man-Sv by the personnel involved in the dismantling and replacement of the recirculation lines.

In 1990, Framatome-Anp undertook the decontamination of the primary circuit pipe ends and SG channel head in the context of the first SG replacement performed in France at Dampierre NPP. This was also the first time chemical decontamination had been used on such an operation in Europe.
For this operation Framatome-Anp applied and compared two different techniques; a dilute chemical process developed by the then British CEGB called LOMI and an electro-decontamination process using phosphoric acid.

Framatome-Anp not only supplied the equipment and engineering expertise for the LOMI process but performed the safety case and supervision for the operation of both techniques. The LOMI process gave the best results with decontamination factors of over 70 being achieved.

Decontamination operations for following SG replacement were performed by Framatome-Anp in association with it's affiliated company STMI using a dilute chemical process developed and patented by EDF (French Utility), called EMMAC.
This same process is also used for the decontamination of chemical and volume control system heat exchangers. Today this process is used at the SOMANU (Framatome-Anp subsidiary) hot repair and maintenance workshop at Maubeuge in France. This facility consisting of four 1m3 vats and two parallelepiped vats, 4.2 metres long, is used to decontaminate equipment and components for disassembly/assembly and machining operations.
Approximately 10 primary cooling pumps per year which arrive for repairs and with an initial activity level of 100 GBq are decontaminated by up to a factor of 50 using the EMMAC process.

In 1992, Framatome-Anp qualified a CEA (French Atomic Energy Authority), decontamination process using boron oxide high pressure jetting for use on reactor vessel heads at Bugey NPP.
The aim of the operation was to remove a smooth film of contamination to enable expert examination of the vessel head adapters that showed signs of stress corrosion cracking. This low aggressivity technique which enabled a decontamination factor of up to 5 to be achieved, was chosen because it is simple to apply and the resulting effluent could be easily processed through the normal plant effluent treatment system.

Between 1992 and 1993 Framatome-Anp undertook hard chemical decontamination operations on a regenerative heat exchanger from Tricastin NPP and a steam generator at Dampiere NPP in France using the STUDSVIK patented SODP process. This process makes use of a strong oxidant consisting of cerium 4 continuously reoxidised by ozone in a nitric acid solution.
In each of the projects, Framatome-Anp undertook the engineering design studies and participated in the operational phase with EDF and GAGNERAUD. Furthermore, Framatome-Anp supplied the decontamination equipment and assisted STUDSVIK with the decontamination of 2 PHWR steam generators at Agesta NPP in Sweden.
This process enabled decontamination factors of over 1000 to be achieved on inconel 600.

Recently Framatome-Anp has become a licencee of the EPRI Decontamination For Decommissioning (DFD) process through its US subsiduary Framatome-Anp TECHNOLOGIES INCORPORATED (FTI).
This process combines the advantages of applying a dilute chemical solution similar to that used on operating plants (LOMI or EMMAC), and achieves high decontamination factors (over 1000), as obtained from hard chemical processes. The process, as it's name suggests, is specifically aimed for decommissioning activities where the goal is to obtain "free release" levels for the treated component.

Framatome-Anp has performed successful turnkey secondary side cleanings at Nogent, St Alban and Fessenheim NPPs in France using the EDF chemical cleaning process and our US subsidiary FTI has successfully used the EPRI SGOG and high temperature chemical cleaning processes at Pickering, Palo Verde and Byron NPPs.
FTI has recently completed the worlds largest chemical cleaning to date at the Southern California Edison San Onofre NPP where some 35 tonnes of deposits were removed from steam generators at the station's Unit 2 and 3, enabling steam pressure and MW generation to be recovered.

Over the last 12 years Framatome-Anp has strived to meet the objectives assigned to chemical decontamination and cleaning operations. Early experience was gained using CAN-DECON, LOMI and SODP processes but has since evolved to the more appropriate or easier to apply EMMAC and DFD processes which we offer today.
Through this wealth of experience gained in using a wide range of technologies, Framatome-Anp specialists are able to recommend appropriate processes to meet clients specific needs.
Our capabilities include process development, corrosion monitoring, plant chemistry, system design, fabrication and operation.