Figure 4.1 Dock 8 HF Supply System - DOE-HDBK-1100-20040036

DOE-HDBK-1100-2004

Figure 4.1 Dock 8 HF Supply System

EXAMPLE PROCESS 1: DOCK 8 HF SUPPLY SYSTEM.

The dock 8 HF supply system is designed to supply gaseous HF, under pressure, to a fluid

bed reactor to produce uranium tetrafluoride. The gaseous HF is created by heating and vaporizing anhydrous liquid HF that is brought to the

system in large portable cylinders. The vaporizer room is heated and has an exhaust fan in the wall near the roof. When the system is in

operation, the nitrogen (N2) pressurization system supplies 30-psig nitrogen to the top of the HF cylinder. The cylinder, which contains about

850 pounds of anhydrous HF when full, is on a calibrated scale and is connected to the nitrogen and HF piping systems by pigtail connectors.

The nitrogen pressure forces liquid HF to the vaporizer, which is heated by a hot water blanket supplied by a water heater and circulating pump.

The liquid HF is heated to its vaporization temperature at the desired pressure, and the resulting gaseous HF is directed to the fluid bed reactor,

regulated at 25 psig.

The designed safety system components in the HF feed station are the nitrogen pressure regulator and the nitrogen overpressure relief valves. To

provide overpressure protection for the vaporizer, relief valves are fitted to piping connected to the top of the vaporizer and supply cylinder. A

rupture disc, with a rupture pressure rating somewhat higher than the relief valve setting, is provided upstream of each of the relief valves to

protect the valves from continuous exposure to the corrosive HF environment. Between the rupture disc on the vaporizer and the relief valve is a

pipe tee to a manual vent with a block valve near the discharge. This valve can be opened manually to relieve pressure between the rupture disc

and relief valve or to vent the system during maintenance. A pressure gage is attached to the vent line upstream of the block valve. A plastic

hose is connected to the vent line pipe to direct vent gas to a plastic collection bottle. The collection bottle normally contains water that covers

the end of the vent line hose to absorb vent fumes/vapors.

5. This description is taken from Hummer, John J., et al., 1992.