|NEWS AND INFORMATION
|Year : 2020 | Volume
| Issue : 3 | Page : 185-187
Some information on dirty bomb
Ex Radiochemistry Division, BARC, 83, Zarina Park, Mankhurd, Mumbai, Maharashtra, India
|Date of Submission||21-Jun-2020|
|Date of Decision||15-Jul-2020|
|Date of Acceptance||23-Jul-2020|
|Date of Web Publication||6-Jan-2021|
Ex Radiochemistry Division, BARC, 83, Zarina Park, Mankhurd, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Manchanda V. Some information on dirty bomb. Radiat Prot Environ 2020;43:185-7
| Introduction|| |
In nuclear parlance, Clean Bomb is a nuclear device with reduced amount of radioactive fallout. It is a high-efficiency nuclear weapon design which generates almost all of its explosive energy in the form of nuclear fusion but does not create harmful fission products.
On the other hand, dirty bomb is not a nuclear device. A “dirty bomb” is a type of a “radiological dispersal device” (RDD) that combines a conventional explosive, such as dynamite/RDX with radioactive material(s). Explosion carries the radioactive material into the surroundings areas. A dirty bomb is not a “Weapon of Mass Destruction” but a “Weapon of Mass Disruption.” Main objective of the architects of this device (terrorists) is to cause panic. In addition, it is intended to coerce or to intimidate governments or societies in the pursuit of goals that are generally political or ideological. It is possible as a consequence of the explosion; prolonged sealing of some business complexes could disrupt economic activity.
Since the 9/11 Twin Tower Attacks in the USA, the fear of terrorist groups using dirty bombs has increased immensely. In addition, misguided statement of United States Attorney General John Ashcroft on June 10, 2002, after 9/11, “A radioactive 'dirty bomb' spreads radioactive material that is highly toxic to humans and can cause mass death and injury” may have contributed unnecessarily to the public fear of a dirty bomb.
Most RDDs would not release enough radiation to kill people or cause severe illness. The conventional explosive itself would be more harmful to people than the radioactive material. However, an RDD explosion, apart from creating fear and panic, is likely to contaminate people and property within few hundred meters. Decontamination of victims, as well as of the affected area, might require the help of professionals dealing with radiation protection.
For those affected by a RDD incident, the radiation health risks (i.e., increased probability of developing cancer later in life due to radiation exposure) are comparatively small, comparable to the health risk from smoking cigarettes for few months. The fear of radiation is not always logical. Although the exposure might be minimal, many people find radiation exposure, especially frightening, because it is something they cannot see or feel, and it therefore becomes an unknown source of danger. Dealing with public fear may prove the greatest challenge in case of an RDD event. Early communications from trustworthy sources may help reduce the possible psychological effects.
| Radionuclides Used in Dirty Bombs|| |
The extent of local contamination would depend on a number of factors, including the size of the explosive, the amount and type of radioactive materials used, the means of dispersal, and weather conditions. Those closest to the RDD would be most likely to be injured by the explosion rather than released radioactivity. As radioactive material spreads, it becomes less concentrated and less harmful.
Radiological damage caused by a dirty bomb depends on the nature (characteristics) and quantity of the radionuclide used as given below
- The source should be “sufficiently” radioactive (high strength) to create direct radiological damage on explosion or at least to perform societal damage or disruption. Naturally occurring long half-live radionuclides such as Th-232 and U-238 are ineffective. Similarly, radionuclides with half-lives of hours and days are too short lived and will not last long enough for any meaningful residual radioactivity on the site of explosion
- The source should be transportable with minimum shielding to protect the carrier and easy maneuverability. It means that radionuclides emitting high-energy gammas and SF neutrons requiring heavy shielding are not suitable. In addition, such sources are easy to be detected by surveillance agencies. On the other hand, radionuclides of half-lives of few years are preferred
- The source should be sufficiently dispersible to effectively contaminate the area around the explosion. The radionuclide should have high volatility and high solubility.
Possible RDD material could come from the millions of radioactive sources used worldwide in the industry, for medical purposes, and in academic applications, mainly for research. Of these sources, there exist thousands of sources scattered throughout the world which are reported lost and are referred to as orphan sources. The terrorists could lay their hands on either such sources or indulge in theft/smuggling activities from protected nuclear establishments. [Table 1] lists the reactor produced radioisotopes along with their effectiveness in RDDs.
|Table 1: Reactor produced radioisotopes and their relative effectiveness in radiological dispersal device|
Click here to view
| Reported Attempts Made for Dirty Bombs|| |
Beta-emitting radionuclides such as Cs-137, Sr-90, and Co-60 as well as alpha-emitting radionuclides such as Am-241 and Pu-238 are relatively more effective dirty bomb materials. There are several reports of unsuccessful attempts to detonate dirty bomb globally. The first attempt of radiological terror was carried out in November 1995 by a group of Chechen separatists, who buried a cesium-137 source wrapped in explosives at the Izmaylovsky Park in Moscow. In December 1998, a second attempt was announced by the Chechen Security Service, who discovered a container filled with radioactive materials attached to an explosive mine. In 2006, DhirenBarot from North London pleaded guilty of conspiring to murder innocent people within the United Kingdom and United States using a radioactive dirty bomb though the nature of radionuclides intended to be used is not available. In January 2009, a leaked FBI report described the results of a search of the Maine Home of James G. Cummings, a white supremacist, who had been shot and killed by his spouse. Investigators found conventional explosives as well as literature on cesium-137, strontium-90, and cobalt-60. In April 2009, the Security Service of Ukraine announced the arrest of a legislator and two businessmen from the Ternopil Oblast, who had a plan to use probably americium, a radioactive material which is commonly used in smoke detectors but can also be used in a dirty bomb. In 2013, thieves in Mexico stole a shipment of cobalt-60 pellets used in hospital radiotherapy machines, although the shipment was later recovered intact. In July 2014, ISIS militants seized 88 pounds (40 kg) of uranium compounds from Mosul University. The material was unenriched and so could not be used to build a conventional fission bomb, but a dirty bomb is a theoretical possibility. In November 2016, thieves stole a device containing iridium-192 from an Iranian nuclear power plant which could be used to construct a dirty bomb.
Due to all failed attempts, there are no data available of the consequences of dirty bomb explosion. There are, however, some data available of accidental release of radioactivity due to ignorance. In a way, we can compare these events of radioactivity release to the spread of radioactivity in dirty bomb. Adverse effects on individuals in the two cases are likely to be similar if the timely action is not taken to isolate the source of radiation and ensure that the general public does not receive significant exposure.
In Brazil, in 1987, two metal scavengers broke into an abandoned radiotherapy clinic and removed teletherapy units containing TBq of137Cs activity in a capsule. They decided to cut open the capsule to sell it as metal scrap and in the process exposed themselves, friends, and family members with powdered137CsCl. It took 2 weeks to relate the symptoms of exposure to the intense radioactive source. During this period of suspense, more than 200 persons were exposed, with few of them seriously and eventually five persons died.
A similar incident happened at Delhi in 2010. A Co-60 source (AECL gamma cell 220) was installed in the late sixties at Chemistry Department, Delhi University, and was not in use for about three decades. Subsequently, this source along with shielding was abandoned within the department. During a renovation exercise of the department, Co-60 source was sold to metal scrap dealer. Eventually, the exposed source found way in the scrap market, resulting in seven radiation injuries and one death.
| Containment and Detection of Radioactivity|| |
The impact of radiation exposure would be determined by the nature (neutron, gamma, beta, or alpha) and amount of radiation absorbed by the body. Latter, in turn, it depends on the distance of the source radiation to an individual as well as length of exposure time. Means of exposure, viz., external or internal (absorbed by the skin, inhaled, or ingested), is another important factor. Prompt detection of radiations helps the local authorities to advise the public about the protective measures.
As a corollary, radiological impact can be minimized by taking following steps:
- Do not touch anything on the site of explosion
- Cover mouth and nose with wet cloth
- Move to nearest shelter
- Remove personal wears and keep them aside sealed in a bag
- Take shower using soap/body wash.
Radiation can be readily detected with equipment carried by many emergency responders. PocketType instruments scan an area for radioactive materials. These devices such as smart phones can be clipped on the belt of the surveillance officer, have an alarm threshold of three times the normal radiation levels, and have a long battery life. Handheld instruments are used to detect all types of radiation (including neutron) and may be used to search specific targets in a short time. Fixed, installed instruments provide a continuous, automatic detection system that can monitor pedestrians and vehicles that pass close to the detectors, as performance is directly related to range. Detectors are available which continuously analyze the environment and immediately identify the class of radioactive agent present and even the actual isotope and thus the properties of emitting radiations. Radiation Portal Monitor, Geiger Counters, and Gamma-Ray Detectors are often employed for open sources. Sealed sources may also be detected by X-ray inspection and by infrared detectors. Nanosecond neutron analysis (NNA) detector designed originally for the detection of explosives and hazardous chemicals can detect fissile material across a thick lead wall.
| Conclusions|| |
The reported incidents highlight the importance of keeping track of all radioactive sources by the regulating bodies. Procurement, transportation, use, and disposal of radioactive sources have to be carried out under the stringent watch of the regulator, and the prescribed guidelines have to be observed till the source is disposed safely. Long half-lives of some of the radionuclides necessitate the surveillance over a period beyond the active service period of individuals. Thus there is a need for institutional mechanism to take custody of the sources when they are received and more so when these are out of use. Medical/health sector and academic institutes where large-scale movements of public are unavoidable are particularly vulnerable for accidents, as well as for smuggling. It is also necessary to keep a vigil on the orphaned sources to avoid their misuse (intended or otherwise) by regulating authority. As radiations emitted have no smell or color, they turn out to be silent health hazard till the symptoms of over exposure are manifested.
It is important to design a strategy to deal with dirty bomb, considering the principle of containment and evacuation. However, the basic question if the explosion is a dirty bomb or just a conventional bomb is a matter which requires a paradigm shift in the approach of disaster management group. It is necessary that the forensic investigation must include radioactivity measurements on the samples retrieved from every artificial explosion site. Access of the site should be restricted till the report of radioactivity test is available. Little is known about civil preparedness to respond to a dirty bomb attack. Awareness about such accidents needs to increase through school curricula and short documentaries, which can be screened on electronic media. It is also important that regulating authority keeps track of all the sources within its jurisdiction from installation to disposal. It is also worthwhile to track lost (orphaned) sources to ensure these do not land in the hands of terrorist groups or accidentally release radioactivity in public places.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Ring JP. Radiation risks and dirty bombs. Radiation safety. J Health Physics 2004;86 Suppl 1:S42-7.
Samuel Apikyan J, Diamond D, Ralph W. Prevention, Detection and Response to Nuclear and Radiological Threats. ISBN140204920X: Springer; Brussels, Belgium; 2008.