The radioisotope used in industrial radiography for the rapid checking of faults in welds and casting is

1. Analyze the question

The question asks for the specific radioisotope used in industrial applications, specifically for non-destructive testing (NDT) like checking for structural faults in welds and metal castings.

2. Explain the concept

Radioisotopes are unstable isotopes of elements that emit radiation. In industrial radiography, we look for isotopes that emit gamma rays. Gamma rays have high penetrating power, allowing them to pass through thick metal objects to reveal internal cracks, voids, or defects on a photographic film (similar to an X-ray).

• Phosphorus-32: Primarily used in medicine and agriculture as a tracer to study plant metabolism and in treating certain blood disorders.
• Cobalt-60: A strong gamma-ray emitter. Because of its high energy and long half-life, it is the standard choice for industrial radiography to inspect heavy-duty welds and castings.
• Carbon-14: Used primarily for radiocarbon dating of organic materials (archaeology).
• Iodine-131: Used extensively in medicine for diagnosing and treating thyroid gland conditions.

3. Show the solution

• Step 1: Identify the purpose of the radioisotope. We need a source of high-energy gamma radiation capable of penetrating dense materials like steel welds.
• Step 2: Evaluate the options. Phosphorus-32 and Carbon-14 are beta emitters, which lack the penetrating power required for thick metal inspection. Iodine-131 is primarily used for biological/medical applications.
• Step 3: Confirm the application of Cobalt-60. Cobalt-60 produces high-energy gamma photons that can easily penetrate steel castings, making it the ideal choice for industrial radiography.

4. Identify the answer

The correct radioisotope used for checking faults in welds and castings is Cobalt-60. This matches option B.

5. Exam Tip

To remember this for your JAMB exam, associate the "C" in Cobalt with Casting and Checking welds. Also, remember that Cobalt-60 is the "heavy lifter" of industrial radiography because of its intense gamma radiation.