At-Power, Low-Frequency, Reactor-Power-Spectrum Measurements and Comparison with Oscillation Measurements

Power spectral density measurements were conducted at the Sodium Reactor Experiments (SRE) over a wide range of frequencies and at various power levels. Use of magnetic tape recording and speedup techniques permitted rapid data analysis and excellent resolution. Results were compared with oscillation tests under identical operating conditions and were found to have the same resonance structure but higher amplitude at the resonance peaks and at low frequencies. Investigation resulted in the conclusion that the reactor fission or driving spectrum deviated from white noise at some low frequency.