Various measurements systems used in Nuclear Plant

1. Gourav Gupta
17MMA006
Measurement Systems used
in a Typical Nuclear power
Plant

2. Used for measuring a physical
quantity.
In engineering, it is an activity of
comparing physical quantities.
Eg:-Stopwatch,Electron
Microscope,Autocollimator,etc.
Measuring Instrument

3. In this presentation,we only deal with
instruments used in a Nuclear Power
Plant like:
-Nuclear Power Reactors
-High Temperature Thermocouples
-Optical Fiber Sensor
-Uranium Fission Chamber
-Ionisation Chamber
-Differential Calorimeter,etc

4. Resistance Temperature Detector:
-Consist of wire wrapped around a ceramic or
glass core.
-Produces an electrical signal that changes
resistance as the temperature changes.
-Made of Platinum,Nickel,Copper,etc.
Temperature Themocouples:

5. :
Principle:
The variation of resistance of a pure
metal along with temperature.

6. -Wire is wound on a notched mica cross frame
to achieve small size.
-Coil is protected by a stainless steel well.
-Mica is placed in between the steel well and
resistance wire for better electrical insulation.
:
Construction:

7. RTDs work on a basic correlation between metals and
temperature. As the temperature of a metal increases,
the metal's resistance to the flow of electricity
increases. Similarly, as the temperature of
the RTD resistance element increases, the electrical
resistance, measured in ohms (Ω), increases.
:
Working:

8. Rt=Ro (1+αt+βt2 )
Rt =resistance of metal at t0 C
Ro =temperature of metal at 00 C
α, β =constants.

9. -Influence of radiation on transmission characteristics.
-Main effect of radiation on optical fibres is known to
be an increase of the fibre’s attenuation (reduction in
the length of a signal).
- Optical method is important to the
measurement of nuclear fuel cycle.
Optical Fibre Sensors

10. 1.Based on the sensor location:
-Intrinsic Fibre Optic Sensor
-Extrinsic Fibre Optic Sensor
2.Based on operating principles:
-Intensity Based -Phase Based -Polarization Based
3.Based on application:
-Chemical Sensor -Physical Sensor
Types of Optical Fibre Sensors

11. Intrinsic Type Fibre Optic Sensors:
Sensing takes place within the fibre itself.
Convert an environmental action into a modulation of
light beam passing through it.
It provides distributed sensing over long range distances.

12. Extrinsic Type Fibre Optic Sensors:
 Fibre may be used as an information carriers that show the way to
black box.
 Generates light signal depending on the information arrived at the
black box.
 Black box is made of mirrors or gas.
 Ability to reach places which are unreachable.

13. - Works to detect Neutrons.
-Coated with a small amount of U-235,along the wall.
-Filled with an inert noble gas such as Argon.
-Voltage is applied between outer cylinder and inner
wire creating electric field between cathode and anode.
Fission Chambers:

14. Diagram:

15. -Incident neutron is absorbed with a fissile nucleus and causes
fission.
-Fissile nucleus splits into two fragments. One of the fragment
travel into the gas region of the detector.
-Deposit most of the energy in the fill gas by ionizing the gaseous
atoms.
-Free electrons are collected on the inner anode wire due to
applied volltage,producing current which is output of the chamber.
Working:

16.  Amount of energy generated is propotional to the rate of fission
events produced in the detector.
 Current is proportional to fission rate,and the current is also
proportional to the incident neutron flux.
 The relationship between net neutron fission chamber current
In(t) and neutron flux is given by:
In(t)=F.A.x. f Φn (E,t).⅀f (E) dE
where F is a chamber dependent constant
A is the active detector area
x is the fissile material thickness
Φn (E,t) is the neutron flux as a function of neutron energy
and time
⅀f (E) is the macroscopic fission cross section of the
uranium oxide coating in cm-1 as a function of neutron energy.

17. -Detecting and measuring ionizing radiation by using excitation
effect of incident radiation on a scintillator material.
-Consists of a scintillator which generates photons in response to
incident radiation,a sensitive photomultiplier tube(PMT) which
converts light to an electrical signal and electronics to process this
signal.
-Scintillator consists of a transparent crystal usually a phosphor.
Scintillation Counter:

21. -instrument used for detection of ionization radiation.
-detects alpha particles,beta particles, and gamma rays
using the ionization effect produced in a Gieger-Muller
Tube.
-one of the best-known radiation detection instrument.
Geiger Muller Counter:

22.  Gas-filled device which creates an electric pulse
when radiation interacts with the wall or gas of the
tube.
 Pulses are converted to a reading on the instrument
meter.
 If instrument has a speaker, the pulses also give an
audible sound.
 Common readout unit is counts per minute(cpm).
 Filled with an inert gas such as argon, helium or
neon at low pressure,to which a voltage is applied.
 Ionisation is considerably amplified within the tube
by the Townsend Discharge effect to produce an
easily meaured pulse.