Romans

The AREVA NP Romans site is dedicated to the fabrication of fuel assemblies for nuclear power reactors and fuel elements for research reactors using enriched uranium.

The Romans site houses two basic nuclear installations (BNI): BNI No. 63 (fabrication of fuel elements for research reactors - CERCA) and BNI No. 98 (fabrication of fuel assemblies for nuclear power plants). AREVA NP is the sole operator of the Romans site.

The French Nuclear Safety Authority (ASN), an independent administrative authority, monitors the activities of the site’s two basic nuclear installations. AREVA NP covers both the production of fuel assemblies for nuclear power reactors and for research reactors in terms of safety, radiation protection, environmental protection and the overall management of industrial operations.

Fuel elements and assemblies: three production activities, one industrial site

1. Main stages of the fabrication process of fuel assemblies for nuclear power reactors 

Conversion

Enriched uranium hexafluoride (UF6) is the raw material used at the Romans plant. UF6 is transformed into powdered uranium oxide through a chemical transformation process using conversion furnaces.

Pelletizing

The powder generated in the conversion plant is compacted into cylindrical pellets measuring eight millimeters in diameter and weighing seven grams. The pellets are then sintered in a furnace at 1,700°C until they reach their target strength and density.

Rod manufacturing

The pellets are stacked into zirconium tubes of approximately four meters in height, called cladding. These constitute the first of three safety barriers within the nuclear reactor to prevent any radioactive material from leaking. Each tube is filled with pellets (approximately 300) and sealed at both ends with two plugs. The entire unit constitutes a “fuel rod.”

Assembly

The rods are assembled or “bundled” in a metal structure, called a skeleton, to form a fuel assembly. Each fuel assembly - also known as “fuel bundle” - contains 264 rods. Each step in the manufacturing process is subject to very strict inspection, including dimensional and visual checks. Fuel assemblies make up the reactor core and remain in place, on average, for three to four years. Fission of the uranium within the tank provides the heat needed to generate the steam that is then used to produce electricity.

2. Main stages of the fabrication process of fuel elements for research reactors - CERCA

CERCA produces fuel elements that are supplied to research centers and universities. The plant applies its on-site know-how to produce various types of fuel assemblies.

CERCA also supplies uranium-based medical targets to produce Mo-99. Once irradiated in a research reactor and extracted chemically, they can be used to produce the radioisotope most widely used in medical research, which is Molybdenum 99. This radioisotope plays a key role in a wide range of medical diagnoses and cancer treatments.

Fusion / Grinding

Uranium metal is melted with silicon or aluminium to obtain a uranium alloy. The alloy is then transformed into an extremely fine powder over several steps.

Pressing / Framing

Next, the powder is compressed into a kernel, which is then inserted between an aluminium frame and cover to form a preplate or “sandwich.”

Rolling / Plate inspection

The preplate is then transformed into a fuel plate through successive rolling operations and inspected with several non-destructive exams.

Assembly

Then, the fuel plates are assembled by welding and swedging into a notched aluminium structure that forms the fuel element.

Assembly inspection

Finally, the assemblies go through complete inspection controls to ensure a safe use.

Inspections

3. Main stages of the fabrication process of mechanical parts

The Romans plant produces zirconium- and stainless steel-based parts used in the fabrication of fuel assemblies. These parts are essential to maintain the integrity of fuel assemblies within the nuclear reactor, and are made on-site for the Romans plant’s own purposes as well as for other fuel assembly producers.

Rod clusters play a key role in starting up the reactor, controlling it over a twenty-year period and shutting it down.

The grids serve to position and maintain the fuel rods in place. They also facilitate heat transfer between the fuel assembly and the reactor water.

Caps are parts made of stainless steel and inconel and are situated at the ends of fuel assemblies.