Emergency Preparedness in Nuclear Installations Report
Emergency planning and preparedness is concerned with that sequence of events, where the well-established standards, rules, regulations and procedures governing the use of radioactive materials and the normal maintenance of a facility are no longer being satisfied (Collins and Emmerson, 2005).
Different types of nuclear and radiological emergencies have occurred in the past years because of various causes. Experience gained from responding to these emergencies has underlined the need and importance for developing an efficient response system. The proposed response system must take incorporate infrastructural and functional components, emergency plans, procedures, and internally consistent operational criteria (IAEA, 1998).
International Atomic Energy Agency (IAEA) is of the opinion that many countries are not prepared adequately at present to meet such emergencies. The agency is of the opinion that absence of standard procedures may lead to inefficiency in recovery operations, which eventually would result in severe socioeconomic and political consequences. In this context, this chapter presents a review of the available literature to enhance the knowledge on the emergency preparedness to meet nuclear and radioactive accidents.
Two major events led to the reconsideration of emergency preparedness programs in the nuclear installations. The impact of these events compelled policymakers in different nations to reassess their plans intended to protect the public as well as the environment (Dodd, 1994).
The first major incident accident is the one that occurred in Three Mile Island in 1979. The conclusions drawn from the first accident analysis report of this accident reveals that the failure of the U.S. safety organizational system is the main cause of the accident in Three Mile Island (Dien et al., 2004).
The Chernobyl accident occurred in 1986 highlighted the need to understand organizational issues and stressed the necessity to inculcate safety culture in nuclear installations (Manna, 2007). The importance of organizational safety culture was recognized by the global nuclear power industry after the Chernobyl accident (IAEA, 1986). For example, in Japan, the nuclear emergency preparedness has been augmented from the experience of these accidents.
More particularly the lessons learnt from the criticality accident at the uranium-processing plant in Tokai-Mura, was a turning point in the matter of nuclear emergency preparedness in the country. It led to the enactment of Special Act of Emergency Preparedness for Nuclear Disaster. This Act was dedicated exclusively for nuclear emergencies in the area of Basic Act on Emergency Preparedness (Japan Nuclear Energy Safety Organization).
Organizational Factors and Nuclear Safety
Efficient plant staff and the system of management present in a nuclear establishment is an important line of defense against nuclear accidents. Although management and organizational factors have a significant role in the safety of nuclear installations this fact has been recognized by the nuclear organizations and policymakers only recently (Dien et al., 2004).
Generally, accidents happening in any nuclear organization will have an incubation time. During this time, the organizational context weakens giving room for accident to take place and during this time the efficiency of available barriers degrade emanating warning signals.
There will be weak signals, which will act as indicators for the likelihood of some catastrophic event. However, it is difficult to detect these weak signals and therefore the nuclear organization cannot interpret these signals and act based on them. In most of the cases, such signals are detected after the accident had taken place.
On the other hand, the precursor events are the strongest warning signals. These signals normally do not have any catastrophic consequences, as the likely incidents and accidents are controlled in time and the available barriers prevent the happening of such incidents. There are some organizational factors, which are instrumental in causing an incident or accident in a nuclear installation. They are:
Weakness of the organizational safety culture;
Complexity and inappropriateness of the organization
Limits of operational feedback
Failure of the control mechanisms (Manna, 2007).
It is important that these factors be considered while devising an emergency preparedness plan for a nuclear installation.
Feedback from Experience
The present development in the knowledge about emergency response is based mainly on experience gained from past accidents. Such experience has triggered the evolution of new techniques and procedures for emergency preparedness for mitigating the challenges of nuclear accidents. Past accidents that contributed to influential experiences relate to accidents happened at Windscale (UK, 1957), Three Mile Island (Harrisburg, Pa., USA, 1979), Chernobyl (USSR, now Ukraine, 1986) and Tokai Mura (Japan, 2000).
From the accident at Windscale, it was possible to gain knowledge on the aspects of iodine-exposure and its impact on people affected by the accident. Nuclear scientists were able to establish emergency reference levels during the emergency phase. The objective of establishing the reference levels was to avoid acute health effects, providing for a large safety margin.
From the accident, it was possible to acquire knowledge on the variability of disposition patterns and the importance of atmospheric dispersion covering large areas extending to more than several hundreds of kilometers. The Windscale accident led to the elaboration of emergency plans and definition of reference levels on a national scale for the most important pathways.
From the Three Mile Island accident, considerable experience and knowledge on pre-release decision making and methods of providing information to the public were obtained. Since this accident did not lead to catastrophic releases, lessons were mainly learnt on reactor safety, man-machine interface and accident monitoring (Sohier, 2002).
Investigations that followed the accident revealed the involvement of human factors in nuclear safety, which gave a new focus to the emergency preparedness procedures (World Nuclear Association, 2010).
The accident at the Chernobyl site was the worst and it provided knowledge on the likely global impact of severe nuclear accidents. Immediately after this accident, there were global conventions were undertaken to exchange information on emergency preparedness based on experience gained from the accident.
The conventions also provided for international mutual assistance and agreements on global trade of food products. The accident was responsible to the development of a global focus on the principles of different interventions. It also led to the consideration of late effects of exposure to ionizing radiation in such interventions.
There were new experiences gained on the long-term relocation of large contingent of people and the rehabilitation of contaminated sites. Another area, where knowledge could be gained was the importance of socio-economic aspects covering the decision making process. Chernobyl accident provided in-depth knowledge on the importance of long-range dispersion of people for several thousands of kilometers.
From the after effects of the accident, several new information on health- effects on people like, synergism between burns, skin contamination and external exposure and the risk of thyroid cancer to exposed children, (Sohier, 2002), were found to be grossly underexplored.
The accident at Tokai Mura reminded the nuclear world of a typical scenario in the area of criticality exposure. It educated the concerned authorities and organizations about the need for specific monitoring requirements. The accident evidenced that despite the developments in emergency preparedness after the Chernobyl accident, there were gap in the emergency communication and preparedness procedures (World Nuclear Association, 2007).
The
The is the foundation on which the safety of a nuclear installation depends. This approach implies that a significant accident can take place in a nuclear installation only because of the coincident failure of the multiple protection systems in place. There are three independent levels, which offer the protection to the nuclear facility.
First is the design of the nuclear installation. This is based on the compliance between the as built installation and the independently reviewed safety analysis, the operation by well trained operators, a preventive maintenance programmes, independent inspections etc (Sohier, 2002).
Second is the Design Basis Accidents, in which the design anticipates some accident scenarios, which lead to a breakdown of the abovementioned safety conditions. are installed within the facility to take care of these unexpected scenarios.
Thirdly, some on-site and off-site emergency plans are instituted as the third level of barrier, to protect against the coincident failure of the operational control system and the independent safety system. The objective of these emergency plans is to mitigate the consequences to human beings ad environment. The efficiency of the emergency response will depend on the quality of the preparedness: the emergency plan (Sohier, 2002).
It is important that the off-site emergency plan take into account
releases that are accepted by the safety analysis of Design Basis Accidents, due to their low probability;
releases due to the beyond-design-basis-accidents that were not considered by the safety analysis because of their very low likelihood;
potential releases that were overlooked by the safety analysis (Sohier, 2002).
While preparing a nuclear emergency plan, one has to assume that there is a possibility for the occurrence of each scenario that is physically possible.
Phases of
The processes of assessment, decision and intervention have to be taken up as consecutive steps in any emergency response planning. The first phase is the pre-release phase, during which the emergency response actions take place in the form of preventive measures. Actions in subsequent phases depend on the condition of the environment and the speed with which the conditions change during an emergency.
The phases can be distinguished between the early phase, which can be described as contamination atmosphere and the second phase is the intermediate phase during which the contamination may decrease. The last stage is the late phase which may of the environment. The following table exhibits the phases and the countermeasures to be taken in each phase.
Table exhibits the phases and the countermeasures to be taken in each phase
Source: Sohier, (2002)
Emergency Planning- Organization and Requirements
Until the Chernobyl incident in 1986, most of the countries have been preparing emergency preparedness plans only in respect of isolated nuclear installations. There were only few countries, which prepared emergency plans to protect against events happening outside their borders (NEA/OECD, 1988).
Lessons learnt from Chernobyl and from international emergency exercises, have forced a rethinking and revision of the emergency planning concepts (Thorne, 2009; Swiss Federal Commission for Nuclear and Chemical Protection, 1998). Emergency management involves decision-making to arrive at an optimal response by applying the available information at the right time (NEA/OECD, 1995).
The emergency preparedness planning is undertaken for achieving some definite objectives. First objective is to avoid or to reduce activity release and to mitigate the exposure and its consequences. The emergency planning has the objective of protecting the public, emergency personnel and the environment. The ultimate goal of an emergency planning is to integrate regional radiological emergency preparedness into an overall emergency response system. The emergency planning facilitates recovery from the consequences of exposure.
It is important to develop generic intervention planning and criteria in advance. Although the planning is done in advance, there must be enough flexibility in the plans to incorporate any modification and deviation, when the actual situation is different from what was anticipated at the time of planning.
Emergency preparedness planning involves analysis of potential threats in the form of reference accidents, design basis accidents and beyond design basis accidents. For nuclear installations, it is necessary that Emergency Planning Zones are appropriately defined.
a central area where prompt protective actions against direct radiation from a release plume may be necessary (typically a few km), and for which a detailed implementation plan exists;
an outer area (typically up to a few tens of km), often divided into sectors of 30 to 120, where preparations for effective implementation of protective actions to reduce the long term dose from deposition and ingestion should be developed in advance; decisions should be made based on extensive monitoring and sampling campaigns (Sohier, 2002).
The tasks connected with emergency planning have to be assigned to suitable institutions and organizations. While assigning the tasks clear distinction must be made about, the responsibilities and tasks assigned to each institution and organization. The assignments of tasks among institutions and organizations may vary depending on the circumstances prevailing in different settings.
During an emergency, the main tasks expected from the organizations include detection and recognition of an event and monitoring of the radiological situation. The tasks include implementation of the countermeasures and they have to gather intelligence and monitor on reactions and the success of countermeasures.
Decision-making and Countermeasures
In the pre-release, release and early post-release phases the decision will be made mainly by the emergency organization, while in the later phases government and the normal decision makers will become more and more involved (Sohier, 2002). Normal decision makers decide the planned operations in the recovery phase, when the emergency gradually ends.
It is essential that the roles of experts and decision makers be defined clearly, so that there is no lacking in deciding on the countermeasures. Any proposal on countermeasures must define the aspects that need to be taken into consideration. For instance, radiological experts should confine their decisions to radiological aspects only and allow the relevant experts to take decisions on economic aspects and the responsible political authority to take other decisions (NEA/OECD, 1998).
It is essential that a catalogue of practical countermeasures be prepared in advance, and the catalogue should also indicate the advantages and disadvantages, costs involved and time required for implementation. The catalogue must also indicate other factors relevant for decision-making. These factors include (i) preventive actions like evacuation, sheltering and administration of stable iodine, (ii) mitigation of exposures and consequences, and (iii) facilitation and initiation of recovery.
Practical aspects of Information Management
There are two different ways of providing information to the public operational information and official information. Official information is filtered out of operational information. Operational information is any information prepared for and given to emergency partners and intended to guide or orient them in the analysis, evaluation and decision-making process; it may also contain confidential matter or speculation about possible further developments, forecasts, alternative plans etc and will use scientific and special terminology.
Any information designated as operational may be passed to the media or to the public only after editing and with the permission of the original author. Official information is prepared for and given to media and public and must be edited to suit both the different media and the expected audience. The language must be clear and easy to understand for the general public, (NEA/OECD, 2001).
In addition, it is imperative that the information responsibilities of each member of the emergency organizations are defined and coordinated properly.
The following are some of the guidelines in this respect. (i) each member of the emergency organization must provide information on its own area of responsibility only, (ii) the members should provide information to the public based on verified facts only and there can be no speculation and (iii) all partners in the emergency organization must get the same information as that is provided to the media and public (NEA/OECD, 2001).
