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Nuclear Density Gauge

Nuclear Density Gauge

A nuclear density gauge is a tool used in civil construction. It consists of a radiation source that emits a directed beam of particles and a sensor that counts the received particles that are either reflected by the test material or pass through it. By calculating the percentage of particles that return to the sensor, the gauge can be calibrated to measure the density and inner structure of the test material.
Nuclear density gauges are typically operated in one of two modes:
Ø Direct transmission
Ø Backscatter


Health effects of radiation:
Radiation absorbed by human body will be measured in GRAY (Gy). The amount of gray absorbed by human body will depend on the source of radiation and duration of exposure to the radiation.
Exposure to radiation is classified in to two types:
Acute Exposure: Few Gray (Gy) received in few hours which are more harmful and mainly occurs following radiation accidents.
Chronic Exposure: Small exposures received during long durations which are less harmful and are mainly occupational type of exposures.
Note: Early effects occurs within hours/weeks & months whereas late effects occurs after years to decades

Effects or Symptoms of Radiation against Threshold dose:



Threshold dose

Effects / Symptoms

< 0.1 Gy

No detectable effects

Above 0.1 Gy

Chromosome aberrations detectable

(used for dose estimation of exposed persons)

Above 0.5 Gy

Temporary reduction in WBC count

1 Gy

Nausea, Vomiting, Diarrhea, Fatigue, Headache and Lack of appetite

Time of appearance & severity Depends on dose. Within 1-24 hours  Consequences

Person recovers within 1-2 days.

3 – 5 Gy

Anemia, Infection and Fever

Time of appearance 1-2 months  Consequence

50% of exposed persons die within 60 days

Time of death after exposure     30-60 days

5 – 15 Gy

Damage to small intestine, Diarrhoea, Ulceration, Low blood pressure, Circulatory collapse

Consequences:           Death between 1-2 weeks

>15 Gy

Coma, Tremors, Convulsions, Fever

Time of appearance             within few hours

Consequences                      Death within <5 days
Methods to protect from radiation hazards:
Ø Persons involved in radiation activities should use dosi meter to monitor radioactive source emitting in surroundings
Ø If any of the above symptoms observed one should consult physician immediately
Ø In fabrication industry radiography test (RT) should be replaced by ultrasonic test (UT)
Ø Nucleonic gauges is one of the safest application of radiation in industry as very low activity (micro - to milli-Ci ) sources are used.  Also, these sources are completely shielded
One should work with care with radiation and not with fear



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