How often does Holtec measure radiation and the temperature/heat of each cask? Specifically, how and how often does Holtec measure helium and pressure within each cask?

The storage casks are subject to visual surveillance or external temperature measurements on a pre-defined schedule to ensure that the cask’s flow vents are not obstructed. The design of the storage system is such that, absent an obstruction to the ventilation air flow, there is no physical mechanism for the temperature or pressure in the storage canister to rise uncontrollably. Additionally, the HI-STORM cask has been determined to maintain a large margin of safety with respect to the in-canister temperatures and pressures.