Power Noise Spectra of a Water Reactor in Low Frequency Region

Utsuro, Masahiko; Shibata, Toshikazu

doi:10.3327/jnst.4.267

“…(2) Temperature fluctuation of water coolant due to natural convection at relatively high power level. This noise source has already been affirmed by the foregoing noise analysis at KUR by Utsuro et al (14) and the simulated out-of pile experiments on coolant temperature fluctuation in a natural convection water In the following the noise sources of the types (3) and (4) are fully examined . In order to measure the inlet coolant temperature three chromel-alumel sheathed thermocouples of 1 mm dia.…”

mentioning

confidence: 60%

Some Relations of Neutronic Noise with Fluctuation of Inlet Coolant Temperature and Vibration of a Control Rod Obtained by Simultaneous Measurements at KUR

Oka

¹

,

An

²

,

Kimura

³

et al. 1977

J. Nucl. Sci. Technol.

3

0

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Experiments on reactor noise were conducted at KUR. Depending on the oj)erating condition of the reactor, the cause of the noise are classified into the following four types.1.11 Zero-power noise source due to the branching process of fission neutrons and; or due to random bombardment of neutrons to the detector-under natural circulation of coolant and at essentially zero-power le\·el. 12) Coolant temperature fluctuation due to natural convection-under natural circulation and at relatively high power level. 13) Flow induced vibration of shim control rods-under forced circulation of coolant and at low power le,·eJ. r-!1 Fluctuation of inlet coolant temperature-under forced circulation and near the maximum power level. Vibration of a spare shim control rod and fluctuation of inlet coolant temperature were measured simultaneously with the neutronic noise. Then the noise sources of the types 131 and r-!r were verified. The vibration of a control rod has a broad spectrum in low frequency region besides the large peak at l.J Hz. The fluctuation of inlet coolant temperature is non-white noise and consists of large low frequency component. The theoretically predicted sink structures in the neutronic PSD relating to the transit time of inlet coolant temperature tluctuation through the core were not obsen·ed in the experimental results.

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“…We let [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] and f.=Fc=O in Eq. ( 5 ).…”

Section: Unit Driving Force In Thermal Energy Content Of Fuelunclassified

Analytical Study of Operating Reactor Noise on a Single Channel and a Single Phase Flow Model, (I)

Saito¹

1973

J. Nucl. Sci. Technol.

9

0

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Basic formulas to describe the propagation of a periodically modulated driving source are derived on the distributed model of at-power reactors.Disturbances in the neutron field are regarded as being promptly spread over the whole core in the frequency domain of usual interest for noise and frequency response analyses. On the basis of this approximation, a coupled set of kinetic equations for neutrons, fuel and coolant temperature is derived and solved for the case where a driving source of unit strength is imparted. The relations between the solutions obtained and the formulas for analyzing experiments are established. Comparisons are made qualitatively between the results and those of the lumped model. The existence of a sink and a resonance frequency is examined. The power spectral density of neutron fluctuations in a water reactor under forced circulated cooling shows a sharply varying configuration when the inlet coolant temperature fluctuations are the major noise sources. When the reactor is under natural convective cooling or under liquid metal cooling, no such characteristic features appear.

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“…We let F f [ 2 , s]=6 (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) and f.=Fc=O in Eq. 5.…”

Section: Unit Driving Force In Thermal Energy Content Of Fuelunclassified

Analytical Study of Operating Reactor Noise on a Single Channel and a Single Phase Flow Model, (I)

Saito

¹

1973

Journal of Nuclear Science and Technology

13

0

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Basic formulas to describe the propagation of a periodically modulated driving source are derived on the distributed model of at-power reactors.Disturbances in the neutron field are regarded as being promptly spread over the whole core in the frequency domain of usual interest for noise and frequency response analyses. On the basis of this approximation, a coupled set of kinetic equations for neutrons, fuel and coolant temperature is derived and solved for the case where a driving source of unit strength is imparted. The relations between the solutions obtained and the formulas for analyzing experiments are established. Comparisons are made qualitatively between the results and those of the lumped model. The existence of a sink and a resonance frequency is examined. The power spectral density of neutron fluctuations in a water reactor under forced circulated cooling shows a sharply varying configuration when the inlet coolant temperature fluctuations are the major noise sources. When the reactor is under natural convective cooling or under liquid metal cooling, no such characteristic features appear.

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Power Noise Spectra of a Water Reactor in Low Frequency Region

Cited by 4 publications

References 2 publications

Some Relations of Neutronic Noise with Fluctuation of Inlet Coolant Temperature and Vibration of a Control Rod Obtained by Simultaneous Measurements at KUR

Some Relations of Neutronic Noise with Fluctuation of Inlet Coolant Temperature and Vibration of a Control Rod Obtained by Simultaneous Measurements at KUR

Analytical Study of Operating Reactor Noise on a Single Channel and a Single Phase Flow Model, (I)

Analytical Study of Operating Reactor Noise on a Single Channel and a Single Phase Flow Model, (I)

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