Radioactive air emissions notice of construction: Use of a portable exhauster on 241-A-101 tank during salt well pumping

This document serves as a notice of construction (NOC) for the use of a portable exhauster on 241-A-101 single-shell tank (SST) during salt well pumping and other routine activities at the tank. Approval for salt well pumping is not being requested as this is a routine activity performed to manage the waste within the SST Tank System. The primary objective of providing active ventilation to the 241-A-101 tank is to satisfy the requirements of a Los Alamos National Laboratories (LANL) Safety Analysis Report (SAR) that requires postulated accidents to remain within risk guidelines. It is anticipated that salt well pumping will release gases entrapped within the waste as the liquid level is lowered, because of less hydrostatic force keeping the gases in place. Other routine activities also have the potential to release trapped gases by interrupting gas pockets within the waste. Hanford Site waste tanks must comply with the National Fire Protection Association guidelines, which mandate that flammable gas concentration be less than 25 percent of the lower flammability limits. The LANL SAR indicates that the lower flammability limit may be exceeded during certain postulated accident scenarios. Also, the potentials for electrical (pump motor, heat tracing) and mechanical (equipment installation) spark sources exist. Therefore, because of the presence of ignition sources and the increase in released flammable gases, active ventilation will be required to reduce the ``time at risk`` while performing routine operations at the tank