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"At Worksite 1, we have to maintain the temperature, humidity and cleanliness to support machine construction," says Giovanni Di Giuseppe, Section Leader of the Supply & Service Installation Section. "This means maintaining a temperature of 20 ¡ãC +/- 2 ¡ãC in the winter, and 25 ¡ãC +/- 2 ¡ãC in the summer. Humidity has to be kept below 70 percent, and cleanliness has to conform to ISO 9 [] requirements."

 

One of the goals is to maintain homogenous temperatures between the Assembly Hall¡ªwhere a powerful HVAC system is already functioning¡ªand the crane hall and the Tokamak pit. A change of a few degrees could introduce minute changes in component dimensions that would make it difficult to fit components together during assembly. Maintaining a constant temperature involves heating and air conditioning, but it also involves ventilation to remove the heat generated by workers and by welds.

 

More than twenty "hot points," or welding stations, will be situated in the Tokamak pit. Not only do the welds produce heat that needs to be removed, but they also produce argon which, if left in the pit, would pose a double threat: argon causes anoxia and it triggers fire.

 

"To extract the fumes resulting from the welding we will use specialized equipment, including mobile source capture systems," says Di Giuseppe. "We need to locate the equipment in the crane hall in order to route the ducts inside the pit."

 

 

One source of complexity, especially in the Tokamak pit, is that as the machine is constructed, dead zones arise. These areas start out as big, relatively empty volumes that are easy to ventilate, but gradually they get filled with components¡ªand these components create pockets of trapped air.

 

"Worksite 2 will be a little easier," says Di Giuseppe. "There are no specific temperature or humidity requirements for equipment; however, we do need to maintain conditions that conform with French labour law. There will also be specific activities we will have to support with air locks (isolated rooms where temperature and cleanliness control is required). These activities include cryoline installation, vacuum installation, and Tokamak cooling water system installation. The air locks have to be interfaced to the local ventilation system."

 

"For the rest of the work areas, we need to condition the environment for worker safety, knowing that as many as 180 people may be on three of the building levels at any given time," says Di Giuseppe. "We will put sensors in place to read pollution levels at both worksites. A special team will go on site periodically to read the measurements and check that the pollution is within ISO 9 levels."

 

Beyond worker safety and equipment protection, HVAC will support °ÄÃÅÁùºÏ²Ê¸ßÊÖ efforts to maintain cleanliness, especially in the Assembly Hall. Ventilation will help keep dust and sub-microscopic particles off components that will ultimately wind up in the vacuum vessel. Any contaminants left on such components could reduce fusion output.

 

"During the year 2019, we ran a feasibility study for the temporary ventilation requirements," says Di Giuseppe. "We identified the needs, and laid out the main features of how we will implement the temporary ventilation systems. We would like to award the contracts in the fall and start work by the beginning of next year."