Abstract: A first intensity Az expressed as Az=az×E?, a first reference intensity A0 expressed as A0=a0×E?, a second intensity Bz expressed as Bz=bz×E, and a second reference intensity B0=b0×E, are evaluated. The first intensity and the first reference intensity are of radioactive nuclides generated by a neutron capture reaction of a heavy nuclide or a fission product nuclide. The second intensity and the second reference intensity are of radioactive fission product nuclides except nuclides generated by a neutron capture reaction. The reference intensities are measured where the void fraction is known. Also a correlation curve of (az/a0) and a void fraction is evaluated. Finally an axial void fraction distribution is evaluated based on the value of (az/a0) and the correlation curve.

Abstract: A first intensity Az expressed as Az=az×E?, a first reference intensity A0 expressed as A0=a0×E?, a second intensity Bz expressed as Bz=bz×E, and a second reference intensity B0=b0×E, are evaluated. The first intensity and the first reference intensity are of radioactive nuclides generated by a neutron capture reaction of a heavy nuclide or a fission product nuclide. The second intensity and the second reference intensity are of radioactive fission product nuclides except nuclides generated by a neutron capture reaction. The reference intensities are measured where the void fraction is known. Also a correlation curve of (az/a0) and a void fraction is evaluated. Finally an axial void fraction distribution is evaluated based on the value of (az/a0) and the correlation curve.

Abstract: A first intensity Az expressed as Az=az×E?, a first reference intensity Ao expressed as Ao=ao×E?, a second intensity Bz expressed as Bz=bz×E, and a second reference intensity Bo=bo×E, are evaluated. The first intensity and the first reference intensity are of radioactive nuclides generated by a neutron capture reaction of a heavy nuclide or a fission product nuclide. The second intensity and the second reference intensity are of radioactive fission product nuclides except nuclides generated by a neutron capture reaction. The reference intensities are measured where the void fraction is known. Also a correlation curve of (az/ao) and a void fraction is evaluated. Finally an axial void fraction distribution is evaluated based on the value of (az/ao) and the correlation curve.

Abstract: A stepping motor control apparatus for controlling a stepping motor to drive a fluid flow control valve in an engine includes an operation state monitoring unit for monitoring the operation state of the engine; a step position monitoring unit for monitoring a step position of the stepping motor; a first motor drive direction-determining unit for determining the motor drive direction during normal operations of the stepping motor as determined by a target step position and the present step position of the stepping motor; a second motor drive direction-determining unit for determining the motor drive direction during anomalous operations of the stepping motor; a drive pulse-rate determining unit for determining the pulse generation rate to drive the stepping motor; and a drive unit for driving the stepping motor at the pulse generation rate determined by the drive pulse-rate determining unit.