Australian Clinical Guidelines for Radiological Emergencies - September 2012

Radiation Emergengies

Page last updated: 07 December 2012

Introduction

Emergencies happen when there is a failure of the radiation safety controls in place (e.g. an industrial gamma radiography source left outside its shielded enclosure, or a radioactive package found in a public place). The greatest potential for serious injury arising from these sources comes principally from an unshielded high activity source. Consequences can be very serious, in some cases death, especially if the source is handled by persons who are not familiar with the hazard of radiation, or who do not know that the source is radioactive.

In addition to external irradiation hazard damaged sources of any nature and size can result in contamination of people and/or the environment. As a result of a fire or dispersion by wind or ventilation, contamination can also become airborne. The consequences could include serious skin burns from beta radiation and internal contamination potentially leading to serious health consequences. The situation can be made worse if the accident is not discovered in time and dealt with properly.

Radiological Emergencies

Australia does not have a nuclear power industry. Radiation emergency planning for Australia is directed towards low probability incidents that will have less radiological impact than a major nuclear reactor accident. In Australia, radioactive sources used for radiotherapy and for industrial radiography are tightly controlled and regulated. Radioactive materials in the form of sources are used for a wide variety of purposes in industry, medicine, research and teaching as well as in a number of consumer products on sale to the general public. They are used for radiography, sterilisation units, radiotherapy and nuclear medicine, well logging, level- thickness-, density-, and moisture gauges, anti-static devices and lightning rods and consumer products such as smoke detectors. These sources vary enormously in the magnitude of their activity.

Reactor emergencies

These emergencies may occur when breach of irradiated fuel elements occurs due to loss of coolant. If sufficient venting or failure of containment occurs, high doses may be received by on-site workers or members of the general public in the vicinity of the reactor. Widespread environmental contamination may occur and lead to external exposure of the general public from cloud or ground shine or to internal exposure from inhalation/ingestion of released radionuclides. Reactor emergencies may also result in widespread non-radiological consequences including long lasting psychological effects.

Criticality emergencies

These emergencies may occur when sufficient quantities of special nuclear material are inadvertently allowed to undergo fission. Prompt, high level exposure is generally associated with the emergency, and persons in close proximity can receive very high doses. Workers more than about 10 metres from the assembly receive lower doses (it depends on circumstances, such as physical barriers or shielding). Members of the general public may also receive low doses due to neutron radiation.

Lost or stolen dangerous source

A lost or stolen source is a special case of emergency involving radioactive material. The risk to the public will depend mainly on the total activity involved and the length of time that people may be exposed to the source. It must be assumed that the source may be in possession of persons who do not know its nature and hazard, who may handle or break it resulting in contamination. Such emergencies can result in high doses to the whole body (WB) or localized body areas, and internal or external contamination. Serious injury or death may be a consequence of these emergencies.

Misuse of dangerous industrial sources

These emergencies may occur when proper industrial radiography procedures are not followed. Failure to use exposure control may lead to inadvertent overexposure to workers in the immediate work area. Touching the source for any reason often leads to serious injury to the hands. Whole body exposure in high doses may lead to death.

Emergencies at industrial irradiation facilities most often lead to whole body exposure at high doses. Emergencies involving mobile industrial radiography sources mostly lead to local radiation exposure.

Accidental medical overexposure

Accidental medical overexposure may occur because of miscalculation of the activity of a therapy source, improper function of an X-ray device or accelerator, or when higher activities than intended are inadvertently administered during diagnosis and therapy. When a patient receives a lower dose than that prescribed by the physician this can lead to a serious medical problem. However, this is not considered a radiation emergency, and such a situation is not considered in the manual.

Transport and laboratory emergencies

Many thousands of transport operations occur daily with the use of radiation and radioactive material. Transport can include road, rail, air, or sea. The spectrum of items transported varies greatly and includes nuclear industry products, radiography sources for industrial and medical use, gauges, and consumer products. The largest fraction of transport operations is associated with radiopharmaceuticals for medical use. The main problem with planning for transport emergencies is that they can occur anywhere and potentially affect the general public. Nevertheless, radioactive transport emergencies are, compared to all other categories, extremely rare. Moreover, transport packages are designed to resist different types of emergency situations (fire, pressure, etc). Therefore, even in an emergency, radioactive material will be intact if properly packed in accordance with the appropriate procedure.

Emergencies in laboratories (research or hospital) could have a potential for severe exposure to personnel due to external exposure and/or intake.

Contamination of air, food products and water supplies

Contamination of air, food products and water supplies could result from accidents (e.g. reactor emergency with outside release, damaged and dispersed lost or stolen dangerous source) or intentionally (malicious acts involving radioactive material (e.g. deliberate addition of radioactive material in food/water supply).

As a result of a reactor emergency, the contamination of food/products could lead to the low level exposure of a large number of people. Widespread public health action to restrict contaminated food consumption could be necessary. In the event of intentional contamination of food/products, significant exposure of large numbers of the public is very unlikely. However, there is a potential for significant exposure to small numbers (e.g. contamination of products on store shelves) and to those working with or transporting the products/food. Contamination in excess of national and international trading standards for commodities is possible. Allowing contaminated or potentially contaminated products into the local, national, regional or international distribution system could have massive economic consequences.

Malicious use of radioactive material

There is the possibility that terrorists may commit a malevolent act that involves the use of radioactive materials that could have widespread radiological consequences. These scenarios include:
  • A threat to commit a malevolent act involving the use of radioactive materials
  • A deliberate act to irradiate persons
  • A deliberate act to contaminate food or water supplies with radioactive materials
  • the use of conventional explosives or other mechanisms to disperse radioactive materials, such as a radiation dispersal device (RDD)
  • A deliberate act to contaminate a site or the environment with radioactive materials
  • A sabotage attack upon a nuclear facility aimed at causing an uncontrolled release of radioactive materials.
The suitability of a radioactive source for malevolent use will depend on the size of the source, the type of radiation emitted by the source (alpha emitters are problematic if inhaled or ingested), the half-life of the source, the ease of accessibility to the radioactive material in the source, the portability of the source and the physical and chemical properties of the source (e.g., powdered sources allow for ease of dispersion). For convenience and clarity, radiological dispersal incidents are divided into two broad categories: those involving small and generally highly localized sources and those involving the dispersal of large amounts of radioactive materials over large areas.

Localized Sources

A single or a few, small low-level (containing small amounts of radioactive material) sources may be used with the principal objective of causing fear within a population and ultimately of disrupting the social order. The radioactive material could be packaged in a small container such as an ampoule, shoe box, or even a suit-case sized container. If in liquid form, the material could be dumped into a water reservoir or spilled over some small area; or, to create mayhem over a larger area, it could be released in small amounts from a bicycle, motor vehicle, or even an aircraft. Because the amount of radioactivity is small, the exposure to individuals would also be expected to be low. Thus, the harm from this kind of source is primarily psychosocial, and whatever low external or internal dose is received should produce no immediate adverse health effects and only a small probability of long-term health effects.

Widely Dispersed Sources

Of greater concern are events that result in the dispersal of radioactive materials over large areas through the use of explosives coupled with large amounts of radioactive material. If the target area is populated, individuals injured by the explosion are likely to be contaminated with radioactivity. Greater amounts of radioactive materials would likely be used in such devices and radiation casualties may include individuals who could have received life-threatening levels of exposure. The objective of such a device is similar to that of a smaller source, but is intended to affect an extended area or population. The most likely scenarios involve:
  • use of a solid radioactive material that would be of low enough activity that the construction and delivery of the RDD will not seriously inhibit the terrorist from carrying out the attack
  • radioactive material in some kind of solution, or even a gas.
Large sources of penetrating radiation are difficult to handle safely and without detection by authorities. Shielding materials that are adequate to protect both the individuals who construct these devices, and those who are to deploy them, complicate the design and fabrication of effective weapons.

Nuclear reactors, adjacent spent fuel storage depots, transport vehicles, or any high-level waste site are potential targets for the use of high explosives to disperse into the atmosphere the very high levels of radioactivity associated with materials at these facilities. Australia has no nuclear power reactors and the ANSTO Research Reactor has security measures in place to protect the facilities.

The main radiological consequences of such a malevolent act are likely to be:
  • Fatalities or casualties suffering from the effects of exposure to ionising radiation
  • Radioactive contamination of the location where the radioactive materials were concealed
  • Generation of public fear leading to economic, transport, and medical infrastructure disruption.
Radioactive material can also be hazardous if it gets into a person's body, via inhalation, ingestion or through the open wounds. Inhalation of radioactive material within about 100 metres of a fire or an explosion involving a very large, dangerous source could potentially cause severe deterministic health effects. However, this is probably only possible if the person does not have respiratory protection and stands in the smoke for most of the release duration. Inadvertent ingestion of contamination (e.g. resulting from eating with contaminated hands) could also cause severe deterministic health effects. However this is probably only possible if the person is in direct contact with material that is spilled or leaked from a source.

On the basis of types of high activity radioactive sources in use in Australia, the following scenarios have been used for planning for the medical response:
  • Radiation Exposure Devices (RED) involving the use of Category 1 or 2 60Co, 137Cs, or 192Ir sources.
  • Radiation Dispersal Device (RDD) involving the use of Category 1 or 2 137Cs or 241Am (including Am/Be neutron sources).
  • Radiation poisoning involving the use of 210Po in food or water.

Emergencies involving nuclear devices

A second category of terrorist incidents is the use of nuclear weapons. These weapons might be constructed from nuclear material and conventional explosives or they might be stolen from military stockpiles. The detonation of a weapon with even a small nuclear yield will cause significant radiological consequences in addition to substantial damage to infrastructure. These consequences result from both the initial ionising radiation at the time of detonation and from radioactive fallout that will occur for a considerable time after the initial event.

The probability of a terrorist incident within Australia involving a nuclear device in considered to be negligible. The most likely terrorist nuclear weapons scenario involves the use of a single, low-yield device. There are a number of significant effects that need to be considered in responding to such a catastrophic event. These effects include air blast, ground shock, thermal radiation, the initial nuclear radiation and the residual nuclear radiation. For a 0.01 kT nuclear detonation the range for an initial radiation dose of 4 Gy is of the order 250m. For the same detonation, the range for a radiation dose of 4 Gy in the first hour extends out to 1250 m. (NCRP 138).

The characteristics of possible health consequences arising from these different types of radiation emergencies in Australia are summarised in Table 3.1.

Table 3.1 Characteristics of possible health consequences for different types of radiation emergencies
Type of Radiation Emergency
Effects related to radiation

deterministic

ARS
Effects related to radiation

deterministic

burns
Effects related to radiation

stochastic

detectable
Effects related to radiation

stochastic

protective measures
Effects related to radiation

contaminated persons
Effects related to emergency

conventional trauma
Effects related to emergency

affected area

limited
Effects related to emergency

affected area

widespread
Combined trauma
No. of people

limited
No. of people

large
Nuclear detonation
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
No
Yes
Reactor (OPAL, NPW)
Maybe
Maybe
Maybe
Maybe
Maybe
Maybe
No
Yes
Maybe
Yes
Maybe
Criticality
Maybe
Maybe
No
Maybe
Maybe
Maybe
Yes
Maybe
Maybe
Yes
No
Lost dangerous source
Maybe
Maybe
No
No
Maybe
No
Yes
Maybe
No
Yes
Maybe
Misuse of industrial dangerous source
Maybe
Maybe
No
Maybe
Maybe
No
Yes
Maybe
No
Yes
Maybe
Transport/Laboratory
No
No
No
Maybe
Maybe
Maybe
Yes
No
Maybe
Yes
No
Malicious use of radioactive material
Maybe
Maybe
No
Yes
Maybe
Maybe
No
Yes
Maybe
No
Yes
Radioactive contamination air, food, water
No
No
No
Yes
Yes
No
No
Yes
No
No
Yes

Medical Implications

In a nuclear or radiological emergency, the practical goals of emergency response are to:
  • regain control of the situation
  • prevent or mitigate consequences at the scene
  • prevent the occurrence of deterministic health effects in workers and the public
  • render first aid and manage the treatment of radiation injuries
  • prevent, to the extent practicable, the occurrence of stochastic health effects in the population
  • prevent, to the extent practicable, the occurrence of adverse non-radiological effects on individuals and among the population
  • protect, to the extent practicable, the environment and property
  • prepare, to the extent practicable, for the resumption of normal social and economic activity.
Most of the goals are directly related to human health. Therefore, every medical and technical specialist participating in emergency response has to know and understand the meaning of the terms and the relation between radiation medicine, emergency medicine, physics and radiation protection. Medical response actions need to be in line with the goals of emergency response.

The goals of medical response to nuclear or radiological emergency are to:
  • save lives and perform required emergency medical procedures
  • treat radiation and other injuries
  • provide public advice, counselling and long term medical follow-up.
In general, the clinical management of radiation casualties is the same whether for single or for mass casualty nuclear or radiological emergencies However, the consequences of malicious acts involving radioactive material, resulting in potentially large numbers of casualties, rapid depletion of medical resources, and limited personnel, dictate a different overall medical management strategy for emergency response.

Sealed sources spread in the environment do not present a contamination hazard. As long as these sources are intact, contamination is not possible. Sealed sources can result in low level exposures to persons who come near an individual source. However, persons who handle these sources may suffer significant local radiation injury to the skin and underlying tissues. Mass casualties are not expected when sealed sources are considered.

Radiological dispersal devices (RDDs) are likely to affect relatively small areas compared to a nuclear detonation. The immediate environment, and persons in the area, will become contaminated as the radioactive material is deposited on surfaces. The most effective protection is to leave the affected area. It is highly unlikely that persons in the contaminated area will have medically significant levels of contamination, either external or internal, but fear and concern regarding personal safety will lead to psychological stress.

The medical response required is essentially the same as that required for dealing with a conventional radiation emergency. The differences are:
  • potentially large number of casualties
  • potentially significant conventional medical impact of the blast, and
  • the need to preserve criminal evidence.
This means that the medical response may need to be centrally coordinated, use a network of facilities and establish a triage system, in coordination with radiation specialists, to optimize the use of the medical infrastructure. Conventional trauma victims may be sent to non-radiological specialized facilities, while contaminated severe injuries will have to be treated by facilities with some basic knowledge in the treatment of contaminated casualties. Depending on the number of victims, it may be required to setup a triage and first aid centre near the scene of the terrorist act. All items removed from the casualties need to be preserved for the ensuing criminal investigation.

A nuclear detonation, with the resultant radiation, blast, and thermal injuries, would be catastrophic in comparison to the malicious acts involving conventional explosive or other means of dispersion. In addition to numerous prompt fatalities from conventional trauma, the nuclear fallout and associated damage to structures will severely disrupt civil authority and infrastructure, thereby complicating the delivery of medical care in the affected area. The detonation of a nuclear weapon will result in significant impact on medical response at both pre-hospital and hospital levels. Hundreds to thousands of prompt fatalities are expected in the detonation zone, with an even greater number of persons with blast and burn injuries as one moves away from the detonation zone. The size of the area will be related to the actual yield of the weapon. Triage and initial treatment will affect overall delivery of medical care and stress pre-hospital and hospital resources to their limits. Fallout from these weapon detonations may lead to an even greater number of persons with significant levels of radiation exposure having an even greater impact on the delivery of medical care. Medical resources will be quickly overwhelmed as most survivors will have significant traumatic injuries and thermal burns. The impact of radiation exposure will be secondary to medical management of conventional trauma.

All malicious acts involving radioactive material must be considered as criminal acts and evidence must be retained for investigation by the proper authorities. Emergency medical response plans need to be vigilant for potential malicious acts involving radioactive material. Reporting to appropriate authorities of even a single radiation exposure case can contribute to the initial identification of a malicious act involving radioactive material. Such acts can also involve few seriously injured casualties but can evoke public hysteria and panic.

Table 3.2 Medical / Public Health characteristics of radiation emergencies resulting from malicious acts
Type of event
Relative casualty-type distribution

Lethal

Initial injuries
Relative casualty-type distribution

Lethal

Delayed injuries
Relative casualty-type distribution

Non-lethal

Exposed
individuals
Relative casualty-type distribution

Non-lethal

Non-exposed and/or
psychologically affected
individuals
Nuclear weapon
High
High
High
High
Sealed source dispersal
Low
Intermediate
High
High
Radiological dispersal device
Low
Low
Intermediate
High

Principles of nuclear and radiological medical responses

  • Medical emergencies have priority over external or internal radiological risk, which is characterized by delayed occurrence of injuries.
  • Treatment of internal contamination, enabling decrease in the binding of radionuclides to target organs, is an urgent task and must be planned in the logistical support.
  • External contamination needs to be handled properly at the earliest stage in order to avoid the secondary dispersion of radionuclides in the environment, the contamination of rescuers and the subsequent contamination of casualties. If there is no time or no equipment for control of external contamination, a systematic undressing and showering of uninjured persons must be planned using any available resources of the rescuers and on-scene responders. All procedures and rescue behaviour must avoid internalizing external contamination at the level of the face.
  • Emergency service personnel need to receive training and adequate equipment to protect themselves from radioactivity, chemical and biological hazards. In view of the probability of malicious acts resulting in mass casualties, training must be extended to a large number of personnel.
  • Hospital staff need to receive sufficient training in order to avoid panic behaviour or refusal to give treatment when receiving casualties of CBRN events.