Dirty bombs: what are they and how dangerous are they?

The aim of a 'dirty bomb' is to cause harm by spreading radioactive material that can contaminate an area and poison the human body.

Members of the Seattle Fire Department wear protective suits as they check for radiation, during a mock nuclear "dirty bomb" explosion, as part of a 36-hour terrorism response exercise, May 12, 2003. The scenario, which also involves a bio-terrorrism mock attack in Chicago, is the largest drill ever undertaken in the United States and is a joint effort by the U.S. Department of Homeland Security and U.S. Department of State, in partnership with State and local agencies and organizations. REUTERS/Robert Sorbo

In April 2016, major nations and organisations seeking to prevent nuclear terrorism and proliferation of nuclear material, gathered in Washington for the Nuclear Security Summit (NSS). On the agenda of the U.S.-led discussions were strategies to block terror groups such as the Islamic State from obtaining radioactive material and setting off a 'dirty bomb', or worse. Here, we try and answer a few questions on dirty bombs and its usage.

What is a ‘dirty bomb’?

A dirty bomb combines radioactive material with explosives. The aim is to cause harm by spreading radioactive material that can contaminate an area and poison the human body. This is different from a nuclear bomb that utilises radioactive materials to create an explosion.

What are the materials used for making a ‘dirty bomb’?

Although dirty bombs haven’t been used anywhere, people have reportedly experimented with making one using Cesium-137 and explosives like RDX. High-energy gamma emitters like Cobalt-60 may also be used.

Caesium-137 is produced by nuclear fission processes and is essentially used to treat cancer in hospitals. Although it can be found in small quantities in the environment (from nuclear weapon tests in past), Caesium-137 otherwise is extremely rare. Cobalt-60 is made bombarding Cobalt-59 with a neutron and is used for cancer treatment; it is also used in industries.

What prevents someone from assembling a dirty bomb?

Assembling a radioactive device involving long exposure to very high radiation can make one sick. Radiation exposure can cause burns and radiation sickness, with nausea and hair loss. Prolonged exposure can cause death.

Even if someone succeeds in assembling the bomb it is very difficult to transport a radioactive device. The device will need heavy shielding by metals like lead, which would make it very heavy.

Is India equipped to detect a dirty bomb?

Bhabha Atomic Research Centre (BARC) has developed many systems such as the aerial gamma spectrometry system which can be used to detect even shielded and hidden devices. BARC has also developed technology to detect elements from solid and liquid industrial wastes, as most of these radioactive elements can dissolve in water.

(Based on a PTI interview with K.S. Pradeepkumar, head of emergency preparedness for India’s main nuclear laboratory Bhabha Atomic Research Centre)