The document discusses various measurement instruments used in a nuclear power plant, including resistance temperature detectors (RTDs), thermocouples, optical fiber sensors, fission chambers, scintillation counters, and Geiger-Muller counters. RTDs measure temperature by detecting changes in electrical resistance as temperature varies, while thermocouples use the thermoelectric effect. Optical fiber sensors can detect parameters like temperature, pressure, or radiation over long distances. Fission chambers detect neutrons using coated uranium-235 and the ionization of gas from nuclear fission. Scintillation counters and Geiger-Muller counters both use ionization effects to detect different types of radiation.

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.