[en] Temperature noise measurements were performed at a commercial PWR and the Loss of Fluid Test Facility (LOFT) reactor under varying power levels and core coolant flow rates, producing different core ΔTs. The temperature noise RMS (over the frequency range from 0.1 to 1.0 Hz) is a linear function of core ΔT for the commercial PWR. The data encompass a range of 2.8 to 100% power at constant flow. The temperature noise RMS at LOFT is also a linear function of core ΔT as shown in Fig. 2. The LOFT data included power levels from 27 to 100% and flow rates from 65 to 100%. Over these ranges of operating conditions the temperature noise RMS was independent of the coolant flow rate. For a given core ΔT, the temperature noise RMS is approx. 3 times greater for LOFT than for the commercial PWR