Smoke Alarms, Zaporizhzhia, Litvinenko: RDDs are not Always Explosive


By Andy Oppenheimer

Andy Oppenheimer investigates the threat from radiological dispersal events by terrorists and nation states.  

Despite the fact that the definition of a radiological dispersal device (RDD) is an explosive device laced with a radioisotope, hardly any incidents involving them have been documented.  

When is it an RDD? 

A major problem with such devices is that their detonation would resemble the explosion of an ordinary IED, unless intelligence of theft of radiological materials from a hospital or industrial facility, for example, had been received prior to the attack, and if first responders and forensic teams test for radioactivity. 

If post-event scanning of the scene and victims does not occur, only when victims present with radiation-related injuries at hospital Accident & Emergency departments or develop health problems later will evidence emerge that the bomb was not a conventional IED. 

RDDs may affect localized areas such as a building, block or street, or a larger area of several square miles depending on the nature of the dispersion and the amount and type of radioactive material. All or most fatalities or injuries will be likely due to the explosion itself.  

Despite many experts currently playing down the effects of radiation, the need to decontaminate all affected areas would be paramount, especially in the event of a terrorist or accidental use of a nonexplosive dispersal, such as the abandonment of a radioactive source.

This diagram shows how an americium source ionizes air particles and makes an ionization smoke detector work. 

Historical RDD Incidents are Few and Far Between 

Other than when a handful of RDD emplacements were attempted by Chechen rebels – including in December 1998 when a Security Service team discovered on a railway line a container filled with unidentified radioactive materials attached to a landmine – there are few documented incidents where the presence of an RDD was confirmed. Therefore, we are unable to learn from precedent thus far. 

Equally uncommon are seizures of radioactive material. On December 29, 2022, Border Force officers at London’s Heathrow Airport found ‘traces’ of uranium within a cargo shipment of scrap metal following a routine security screening. A man was later arrested in Cheshire under Section 9 of the Terrorism Act 2006, which covers the making and possession of radioactive devices and materials. The package, which originated in Pakistan and was flown on an Oman Air jet arriving from Muscat, was reportedly headed to a UK-based Iranian business. Uranium’s weight and physical properties make it a poor choice for an RDD. 

Sources and Construction 

Radioactive sources are incorporated in industrial gauges (californium-252); weld inspection instruments (iridium-192); food irradiation (cobalt-60); domestic ionization smoke alarms (americium-241); and hospital and lab equipment (cesium-137 and cobalt-60).  

The last on this list would be an unwieldy choice both in removing the isotope from its housing and then out of the facility. Other gadgets would be less so, but still high-risk. For example, in August 2007 in Michigan, a man was arrested after police found 16 smoke detectors in his home and accused him of trying to extract the americium-241, which has a half-life of 437 years.

Radioactive elements and their half-lives (the length of time it takes for half of the radioactive atoms of a specific radionuclide to decay and become stable). Gamma radiation penetrates skin and body organs; beta burns; and alpha will injure or kill if inhaled or ingested.

A RDD would need to be both powerful enough to disperse the radioactive material, and compact enough to evade detection. Semtex high explosive would be a good choice as it fulfils the above criteria, but it is less available nowadays than during the height of the Provisional IRA bombing campaign in the 1970s, 80s and 90s. Meanwhile, jihadist terrorists tend to blow themselves up rather than emplace IEDs on PIRA-style timers, although they are also used; and other terrorists including small cells and lone actors go for more basic IED construction such as pipe bombs and blackpowder devices cobbled together from fireworks. Passive or active dispersion of unsealed radioactive sources could also be dropped from airborne devices. 

As a terror threat, chemicals are more ubiquitous and easier than RDDs to fashion into a weapon intended to cause injury and mayhem. Furthermore, the common IED in all its forms is somewhat easier to acquire materials for its construction, and most IEDs are far easier to build than any explosive device containing a radiological component. That said, harnessing local knowledge, acquiring intelligence and working with local security and civilian bodies can significantly break a terrorist supply chain, which in the case of radiological IEDs is complex and can be disrupted. Overall, therefore, terrorists are far more likely to use easily accessible weapons and modus operandi to launch their attacks such as IEDs, firearms, stabbing weapons and vehicles in marauding terror attacks (MDAs). 

Dispersal as a Weapon 

The definition of a radiological dispersal weapon when not an explosive device would involve the deliberate release of radioactivity from a facility – a nuclear power plant (NPP), for example. The relentless missile strikes by Russian forces on Ukraine’s Zaporizhzhia NPP since the start of their full-scale invasion in February 2022 is a prime radiological dispersal event (RDE) threat. If an attack causes the release of radioactive material anything like the 1986 Chernobyl disaster, it would be a major war atrocity.

Landsat 9 satellite photograph of Zaporizhzhia NPP that has been bombed repeatedly by the Russians.  1–6: Reactor units 1–6; 7: Electricity pylons; 8: Shelled training building shelled; 9: Radioactive waste storage; 10: Cooling pond; 11: Cooling towers; 12: Kakhovka Reservoir. 
©cmglee, Landsat, USGS/Wikimedia Commons

An RDE may also result from using radioactive material to target a specific individual. Here the noted precedent is the assassination of Russian dissident Alexander Litvinenko with a rare isotope, polonium-210, in November 2006 in London.  

Litvinenko: “a Miniature Nuclear Attack” 

Litvinenko fell ill on November 1, 2006, after a meeting with the two prime suspects, Andrei Lugovoi and Dmitry Kovtun, in the Pine Bar of the Millennium Hotel in Mayfair. He died from alpha radiation poisoning 23 days later.  

The operation to ascertain the victim’s cause of death involved taking samples from dozens of contacts at risk of contamination, detecting physical contamination in premises in the heart of the British capital, and cleaning and re-opening these locations. The Chairman of the 2016 Litvinenko Inquiry, Sir Robert Owen, called the incident “a miniature nuclear attack on the streets of London” that put “many hundreds of people at risk”. London’s first RDE was not caused by a bomb, but a teapot containing enough polonium-210 to kill potentially dozens, and from the inside out. 

In the days following his death, the Health Protection Agency (HPA) tasked with establishing cause of death estimated that Litvinenko had ingested some 4.4 giga-becquerels (GBq) of polonium-210. In performing his autopsy, pathologists had to wear full CBRN personal protective equipment.   

The cause of the radiation sickness was only nailed when an Atomic Weapons Establishment (AWE) scientist recognized a small spike in the urine sample read-out. This was barely above background levels, giving off a very small 803 Kilo electron volts (KeV) gamma ray signal. Having worked on Britain’s early atomic bomb program, he recognized this as emanating from polonium-210 – a vital component of early nuclear bombs and apparently made in just one facility, at the Avangard plant in the closed city of Sarov, Russia. 

Map of the key sites where radioactive substances were found during the Litvinenko investigation. ©BBC News

Multi-Agency Response 

Litvinenko’s movements left radioactive pollution in his wake, including at 56 scenes in the hotels where the prime suspects stayed, as well as at Arsenal football club’s Emirates Stadium. It was also revealed in the Inquiry that traces of polonium were found on the London Underground. 

A full-scale multi-agency response involved the Metropolitan Police, the HPA, the AWE, and Westminster City Council. Nuclear forensic scientists traveled across London to identify locations and people who had come into contact with the prime suspects and their deadly mini-cargo. At its height, the case involved more than 100 police detectives. 

The AWE assessed each location for signs of primary contamination and took numerous surface swabs, and the presence of polonium-210 was established using alpha and gamma spectrometry. Despite the tiny amount of radioactive material used and its relatively short half-life of just 138 days, 22 sites required remediation. 

The Litvinenko RDE illustrated the extent of response and expertise needed and the potential economic harm done. It provided an important guide for the clean-up of premises and how the work would be coordinated. It also highlighted the dangers of alpha radiation. It may also act as a case-study benchmark to guide how first responders and multiple agencies would respond to a future radiological attack. Like the Salisbury Novichok incidents, it came right out of the blue, and the various agencies achieved the impossible. They could likely face even greater challenges next time.

Andy Oppenheimer is author of IRA: The Bombs and the Bullets – A History of Deadly Ingenuity (2008) and a former editor of CBNW and Jane’s NBC Defense. He is a Member of the International Association of Bomb Technicians & Investigators and an Associate Member of the Institute of Explosives Engineers and has written and lectured on CBRNe since 2002.  

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