[en] A report on the LOFT advanced densitometer lab testing that was conducted at ARA-3 in preparation for the non-nuclear L1-4 blowdown at LOFT is presented. The densitometer uses a pulse height analysis method for determining PWR coolant fluid chordal average density. The average density of the coolant fluid along the Cs-137 gamma beam path is determined by measuring the uncollided flux count rate in a Cs-137 photopeak and knowing the LOFT primary coolant hot leg piping geometry. This is an application of a gamma densitometer technique which processes discrete pulses and with no pulse pile-up or integration taking place. Time sampling of the piping and fluid attenuated Cs-137 spectrum provides the data which is related to the changing coolant fluid density as a function of time