Hanford tank farm worker safety and protection from dangerous chemical vapors has been an issue for decades, with no efficient and effective solution in sight. The two major sources of the vapors appear to be from the ventilation ports and the main equipment access port through which cameras, pumps, and other equipment can be inserted into the tank.
This raises two questions:
1) Why is it necessary for the ventilation opening to the atmosphere to be physically located at the tank and in the work area, as opposed to a safe distance away and connected by a pipe to the tank?
2) Why is a negative pressure ventilation system not used so that, when the equipment access port is opened, air goes into the tank, rather than toxic chemical vapors escaping to the local work environment? Such a system would also dissipate hydrogen gas buildup.
These alternatives can be built with cheap and dirty designs, as well as more expensive and cleaner designs. You pick what you are willing to pay for. As for me, I opt for minimal toxic vapors vented to the atmosphere and the least possible exposure of the workers to those vapors.
Richard F. Hart Jr., Richland