IAEA International Atomic Energy Agency
Gauges and well logging
Overview
Day 6 – Lecture 3
IAEA
Objectives
• To give an awareness of the use of
radioactive sources in gauging equipment
• To gain a basic understanding of how these
gauges work
2
IAEA
Content
• What is a nuclear gauge ?
• Applications of gauges in industry
• Gamma gauges
• transmission
• Beta gauges
• transmission and backscatter
• Neutron gauges
• Well logging
3
IAEA
What is a Nuclear Gauge?
• Device used in numerous industries, mostly in process control and quality control.
• Consists basically of a shielded radiation source and a radiation detector
• The radiation interacts with the examined material before reaching the detector, supplying real-time data.
Detector
Material Flow
Shutter
Control
Shielding
Source
Shutter
(Closed)
4
IAEA
Applications of gauges in industry
Quality Control
• Density: rubber, oils, fabric, paper, etc
• Thickness: paper, glass, steel, plastic films
• Level: beverages, cooking oil
Process Control
• Density: cement, mud, liquids, chemical products
• Level: vessels, silos, chemical products, minerals
• Moisture: glass, cement, minerals
5
IAEA
Applications of gauges in industry
Film Thickness Paper Thickness
Beverage Level Oil Level
Quality
control
6
IAEA
Applications of gauges in industry
Process
Control
Mineral Weight
Liquid Flow Mud Flow
Mineral Level
7
IAEA
Types of nuclear gauge
Gauges can be categorised by their mode of
• operation • transmission
• backscatter
• type of radioactive source used • Gamma
• Beta
• Neutron
8
IAEA
Types of nuclear gauge
Transmission: the detector measures the amount of
radiation that passes through the examined
material
9
IAEA
Types of nuclear gauge
Backscatter: the detector is placed on the
same side as the source, measuring the
amount of scattered radiation
10
IAEA
Types of nuclear gauge
• Gamma
• Beta
• Neutron
11
IAEA
Gamma gauges
• Density gauge
• Level gauge
• All operate in transmission mode
• Sources used
• caesium-137
• cobalt-60
• americium-241
12
IAEA
Density gauge
Detector
Typical source:
1 GBq Cs-137
Source
For a known thickness of material, the density can be
deduced by comparing the radiation signal at the
detector with and without the material in the beam
13
IAEA
Point level gauge
High level alarm
Low level alarm
Typical source:
10 GBq Cs-137
Sources Detectors
14
IAEA
Point level gauges
15
IAEA
Liquid fill height gauge
Typical source: 3.7 GBq Am-241
Source Detector
Accept
Reject
Drinks can or bottle
16
IAEA
Liquid fill height gauge
17
IAEA
Beta gauges
• thickness gauge (transmission)
• coating thickness gauge (transmission)
• film thickness gauge (backscatter)
• Sources used
• krypton-85 (encapsulated gas)
• strontium-90 (foil source)
• promethium-147 (foil source)
18
IAEA
Beta thickness gauge
detector
source
web
Typical sources:
3.7 GBq Pm-147
11.1 GBq Kr-85
19
IAEA
Beta thickness gauge
Can be used to
measure: paint, oil,
lubricating films,
plastic, enamel,
ceramic and
phosphate
coatings on metals
and some non-
metals
20
IAEA
Beta thickness gauge
21
IAEA
Beta coating thickness gauge
Detector 1
Source 1
web
Typical source:
37 GBq Kr-85
coating
Source 2
Detector 2
22
IAEA
Beta backscatter gauge
GM counter
Source Metal coating
Substrate
Typical sources:
200 MBq Pm-147, Tl-204
Thicker the coating, the more
backscatter
23
IAEA
Beta backscatter gauge
24
IAEA
Neutron gauges
• hydrocarbon detection gauge
• moisture content gauge
• usually operate in backscatter mode
• Sources used
americium-241/beryllium
plutonium-238/beryllium
25
IAEA
Moisture Gauging using Neutrons
Detector
Neutron shield
Neutron source
High hydrogen
concentration
Low hydrogen
concentration
Typical source
1.85 GBq Am/Be
26
IAEA
Neutron soil moisture gauge
27
IAEA
Nuclear Density Gauge
Am-241/Be
Cs-137
Typical sources:
1.85 GBq Am-241/Be
370 MBq Cs-137 Neutron source
moisture
measurement
gamma source
density
measurement
28
IAEA
Nuclear density gauge
29
IAEA
Well Logging Operations and Equipment
• Well logging
• Drill to Stop
• Measurement or Logging While Drilling
• Borehole logging
• Sources used
• caesium-137 (gamma), typically 40 GBq
• americium-241 / beryllium (neutron), typically
110 GBq
30
IAEA
Drill-to-Stop Well Logging Operation
Well Logging operation that
requires all drilling operations to
cease and requires that parts of
the drilling apparatus are
removed to provide access to
the well bore. The well logging
tool is then lowered into the well
bore to obtain information.
31
IAEA
Drill-to-Stop Well Logging Operation
Well Logging tools
without sources
stored in transport
vehicle
Well Logging tools
without sources at
storage facility
32
IAEA
Measurement While Drilling (MWD)
33
IAEA
Measurement while Drilling (MWD)
Well Logging operations that occur
during the drilling of the well bore
and do not require that the drill stem
or other equipment be removed
from the well. This type of operation
requires that the well logging tool
contains one or more sealed
sources and be located above the
drilling stem to obtain information
through mud telemetry
communications.
34
IAEA
MWD - Neutron Sub
Radioactive
Source Port
Detectors
35
IAEA
MWD – Gamma Sub
Radioactive
Source Port
Detectors
36
IAEA
Geological borehole logging
Geological logging is used to investigate the
geological make-up of an area by lowering test
tools into a borehole. The picture shows a logging
tool containing a neutron source.
37
IAEA
Summary
• Overview of the types of nuclear gauges
found in the workplace
• Brief description of well logging equipment
and process
38