Two identical, circular, wooden spools, 38 cm in outside diameter, in which surveying/measuring tapes are wound. The units are made by the Keuffel and Essel (K&E) company of Manhattan, USA, who produced many different precision drawing and measuring instruments. These two identical tapes were used in measuring cooling water levels (above sea level) at Chalk River associated with both the NRU and NRX reactors. The tapes, instead of having a starting point of zero, start with a marking of 457’ 7”. Their final marking is 484’ 7”. Only after discovery of the drawings of the Bldg. 440 settling basins for incoming reactor cooling water from the Ottawa River was it possible to determine what these markers were associated with. The two numbers correspond to the bottom level of the “clear wells” and the top of the outlet valve in Bldg. 440.
Eleven additional markings exist on the tapes at various irregular intervals. As of 19 November 2019, it had not been established to what the specific vertical positions in Bldg. 440 or in the reactor geometries these numbers corresponded.
