1. Gauges and well logging
Overview
Day 6 – Lecture 3

2. Objectives
To give an awareness of the use of radioactive sources in gauging equipment
To gain a basic understanding of how these gauges work
Lecture notes:
Instructions for the lecturer/trainer

3. Content What is a nuclear gauge ? Applications of gauges in industry
Gamma gauges
transmission
Beta gauges
transmission and backscatter
Neutron gauges
Well logging
Lecture notes:
Instructions for the lecturer/trainer

4. 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)

5. 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
Need examples

6. Applications of gauges in industry
Paper Thickness
Film Thickness
Quality control
Beverage Level
Oil Level

7. Applications of gauges in industry
Mineral Weight
Process Control
Mineral Level
Mud Flow
Liquid Flow

8. Types of nuclear gauge Gauges can be categorised by their mode of
operation
transmission
backscatter
type of radioactive source used
Gamma
Beta
Neutron

9. Types of nuclear gauge
Transmission: the detector measures the amount of radiation that passes through the examined material

10. Types of nuclear gauge
Backscatter: the detector is placed on the same side as the source, measuring the amount of scattered radiation

11. Types of nuclear gauge Gamma Beta Neutron Lecture notes:
Instructions for the lecturer/trainer

12. Gamma gauges Density gauge Level gauge
All operate in transmission mode
Sources used
caesium-137
cobalt-60
americium-241
Lecture notes:
Instructions for the lecturer/trainer

13. Density gauge 1 GBq Cs-137 Detector Source Typical 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 3

14. Point level gauge Sources Detectors Low level alarm High level alarm
Typical source:
10 GBq Cs-137
High level alarm
Sources
Detectors
Low level alarm 3

15. Point level gauges Sources only. Detectors out of view.
Note no power supply needed, nor probes into the vessel.

16. Liquid fill height gauge
Accept
Source
Detector
Typical source:
3.7 GBq Am-241
Drinks can or bottle
Reject 3

17. Liquid fill height gauge

18. 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)
Lecture notes:
Instructions for the lecturer/trainer

19. Beta thickness gauge source web detector Typical sources:
3.7 GBq Pm-147
11.1 GBq Kr-85
web
Describe typical industries using thickness gauges, ranging from tissue paper to steel sheet.
detector 2

20. Beta thickness gauge
Can be used to measure: paint, oil, lubricating films, plastic, enamel, ceramic and phosphate coatings on metals and some non-metals

21. Beta thickness gauge

22. Beta coating thickness gauge
Source 1
Source 2
coating
web
Detector 1
Detector 2
Typical source:
37 GBq Kr-85 2

23. Beta backscatter gauge
Typical sources:
200 MBq Pm-147, Tl-204
GM counter
Source
Beta particles scattered back according to the thickness of the coating - thicker the coating, the more backscatter
Metal coating
Substrate
Thicker the coating, the more backscatter 4

24. Beta backscatter gauge

25. Neutron gauges hydrocarbon detection gauge moisture content gauge
usually operate in backscatter mode
Sources used
americium-241/beryllium
plutonium-238/beryllium
Neutrons are produced when alpha particles impinge upon any of several low atomic weight isotopes including isotopes of lithum, oxygen and carbon. As an example, a representative alpha-beryllium neutron source can be expected to produce approximately 30 neutrons for every one million alpha particles.
Beryllium has a large scattering cross section for high-energy neutrons, thus effectively slowing the neutrons to the thermal energy range where the cross section is low (about barn). The predominant beryllium isotope 9Be also undergoes a (n,2n) neutron reaction to 8Be, that is, beryllium is a neutron multiplier, releasing more neutrons than it absorbs. This nuclear reaction is:
94Be + n → 2(42He) + 2n
Instructions for the lecturer/trainer

26. Moisture Gauging using Neutrons
Typical source
1.85 GBq Am/Be
Detector
Neutron shield
High hydrogen
concentration
Alpha (a) 5,443 (12.8%) & 5,486 (85.2%) KeV
Neutron (n) - 4,500 KeV
Neutron source
Low hydrogen
concentration

27. Neutron soil moisture gauge

28. Nuclear Density Gauge Neutron source moisture measurement gamma source
Typical sources:
1.85 GBq Am-241/Be
370 MBq Cs-137
Neutron source
moisture
measurement
Am-241/Be
gamma source
density measurement
Cs-137

29. Nuclear density gauge

30. Well Logging Operations and Equipment
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

31. 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.

32. Drill-to-Stop Well Logging Operation
Well Logging tools without sources at storage facility
Well Logging tools without sources stored in transport vehicle

33. Measurement While Drilling (MWD)

34. 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.

35. Radioactive Source Port
MWD - Neutron Sub
Radioactive Source Port
Detectors

36. Radioactive Source Port
MWD – Gamma Sub
Radioactive Source Port
Detectors

37. 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.

38. Summary Overview of the types of nuclear gauges found in the workplace
Brief description of well logging equipment and process
Lecture notes:
Instructions for the lecturer/trainer