Nuclear and Radiological Emergency

 Nuclear and Radiological Emergency

The growth in the application of nuclear science and technology in the fields of power generation, medicine, industry, agriculture, research and defence has led to an increase in the risk of occurrence of Nuclear and Radiological emergencies. 

India has traditionally been vulnerable to natural disasters on account of its unique geo climatic conditions and it has, of late, like all other countries in the world, become equally vulnerable to various man-made disasters. 

Nuclear and Radiological Emergency can arise in a nuclear facility at plant level leading to plant/ site or offsite emergency depending upon the extent of its impact on the surroundings. It can also take place while using radiation sources, either at Hospitals, Industries, Agriculture or Research Institutions due to loss or misplacement or due to faulty handling. The other events that can lead to Nuclear or Radiological Emergency in the public domain, include, accident of a vehicle carrying radioactive/nuclear material, due of an orphan source i.e. the source which is not under regulatory control or due to usage of radiation source/radioactive material in Malevolant activities.

Any radiation incident resulting in or having a potential to result in exposure and/or contamination of the workers or the public in excess of the respective permissible limits can lead to a nuclear/radiological emergency. 

Sad memories of the use of nuclear weapons dropped on Hiroshima and Nagasaki, and the wide publicity given to the reactor accidents at Three Mile Island (TMI) in USA and Chernobyl in erstwhile USSR, have strongly influenced the public perception of any nuclear or radiological emergency to be most often linked, erroneously though, to only these events. However, one must be prepared to face nuclear/radiological emergencies of lower magnitudes and ensure that the impact of such an emergency (which,for a given magnitude, is likely to be much greater today because of higher population densities coupled with an enhanced urban infrastructure due to economic prosperity) is always kept under control. It may be noted that better infrastructure can be helpful during such incidences in terms of enhance communication, transport and medical support. 

For improving the quality of life in society, India has embarked upon a large programme of using nuclear energy for generation of electricity. As on date, India has 20 power reactors and three research reactors in operation along with five power reactors under construction. It is also planned to explore setting up Thorium based reactors to meet its ever increasing energy needs. The country is  also at the verge of making operational the first 500MW prototype Fast Breeder Reactor (PFBR)  after a prolonged experience of operation of FBTR (Fast Breeder Test Reactor). Further, the country utilises  adioisotopes in a variety of applications in the non-power sector, viz., in the field of industry, agriculture, medicine, research, etc. Due to the inherent safety culture, the best safety practices and standards followed in these applications and effective regulation by the Atomic Energy Regulatory Board, the radiation dose to which the persons working in nuclear/radiation facilities are exposed to, is well within the permissible limits and the risk of its impact on the public domain is very low. 

However, nuclear emergencies can still arise due to factors beyond the control of the operating agencies; e.g., human error, system failure, sabotage, earthquake, cyclone, flood, etc. Such failures, even though of very low probability, may lead to an on-site or off-site emergency. To combat this, a number of system upgrades have been planned to mitigate/prevent such emergencies. However, proper emergency preparedness plans must be in place so that there is minimum avoidable loss of life, livelihood, property and impact on the environment.

Preparedness at Nuclear Facilities

The probability of a major accident at nuclear facilities leading to the release of large quantities of radioactivity into the environment is always ensured to be negligibly small. However, even in the event of a major release into the environment, the prompt and effective implementation of countermeasures can reduce the radiological consequences for the public and the environment.

Preparedness for Nuclear/Radiological Emergencies

The handling of nuclear emergencies requires coordination among different service groups of the nuclear facility. In the event of potential radiological consequences in the public domain, all the authorities at the three levels, i.e., district, state and central, will play a vital role and assist the offsite officials in effectively responding to and keeping the public informed on the precautions to be taken.

Major Responsibilities of Nuclear Power Plant Operators

This includes the arrangements required to promptly classify an emergency, mitigate the emergency, notify and recommend protective actions off the site consistent with international guidelines, protect those on site, obtain off-site assistance, conduct environmental monitoring of the affected area and assist off-site officials in keeping the public informed.

Major Responsibilities of Off-Site Officials

This includes the arrangements required to promptly implement protective actions and countermeasures in the affected area.

Emergency Preparedness for Nuclear Power Plants

Since the proper implementation of countermeasures can significantly reduce the consequences of an emergency situation, it is mandatory for all nuclear facilities that there must be a comprehensive emergency preparedness plan. Prior to the issuance of a license for the operation of a nuclear facility, the AERB ensures that the facility has the Emergency Response Manuals for the three main types of emergencies, viz., plant, on-site and off-site, and that the plans are in place to handle these types of emergencies. The operators of nuclear facilities must make an assessment of the type and quantum of release of radioactivity under various accident conditions and the extent to which it can spread into the environment.

Plant Emergency

When the radiological consequences of an abnormal situation are expected to remain confined to the plant boundary or a section of the plant, it is described as a plant emergency. Nuclear facilities in the country already have the following provisions for the detection, classification, notification and mitigation of any emergency situation:

• Emergency operating procedures for the assessment of an emergency condition and its mitigation.
• Pre-identification of any facility-specific, abnormal situation for classification of a plant and site emergency.
• Facility-specific, approved nuclear emergency response plans specifying the jobs of all the functionaries who have been assigned roles during the emergency.
• Alerting the plant personnel by sounding the emergency siren and making an emergency announcement.
• Adequate means for communicating a notification to the emergency response organisations at the facility, the district and state authorities, CMG of DAE and the central government authorities.
• Identified assembly locations for plant personnel and casual visitors for their accounting, and assessment of persons trapped in the radiological areas.
• Formation of rescue teams and activation of a treatment area and decontamination centre.
• Radiation survey around the plant and outside the plant and site boundaries.
• Assessment of wind speed, wind direction and the affected sector around the nuclear facility.
• Whenever required, the nuclear facility is able to mobilise the services of the ambulance and paramedical staff at its site.
• Equipment and materials for handling a nuclear emergency are kept at a designated place of the nuclear facility and ERC (Emergency Response Centre).

On-Site Emergencies

An accidental release of radioactivity or the potential of release of activity extending beyond the plant, but confined to the site boundary, constitutes a site emergency condition. In addition to all the provisions applicable in a plant emergency, the following additional provisions are ensured:

• Extensive radiological survey for an assessment of the radiological conditions within the site boundary of the nuclear facility.
• Suitable prophylaxis to be made available at all assembly areas for administration to plant personnel, in case the situation demands.
• Identification of temporary shelters within the facility/site for shifting plant personnel, in case required.
• Provision of a fleet of vehicles for evacuation of plant personnel from the site to a safer place.
• Provision of fixed and portable contamination monitors to check contaminated personnel/vehicles leaving the site.
• On sensing the potential of release of radioactivity which can transgress into the public domain, the concerned district authorities are alerted to be on standby for emergency operations in the public domain.
• Radiological monitoring of the environment in the EPZ (16 km radius around the plant).

Off-Site Emergencies

On recognising the potential for an uncontrolled release of radioactivity into the public domain, the concerned district authorities are alerted to be on standby for emergency response operations. In addition to all the provisions applicable in plant emergency and site emergency, the following additional provisions are to be ensured for handling a nuclear emergency in the public domain:

• Pre-identification of plant conditions which can lead to an emergency in the public domain.
• An assessment of the radiological status at the site boundary and in the public domain.

For handling of an off-site emergency condition in an NPP, there is an off-site emergency committee headed by the district magistrate of the concerned district and supported by the district subcommittee, which include chiefs of all public service departments relevant to emergency management in the district and also the Head of the Site Emergency Committee of the nuclear facility for technical advice. This committee takes decisions pertaining to the handling of a nuclear emergency outside the site boundary and ensures implementation of countermeasures such as sheltering, prophylaxis and evacuation and resettlement, including maintenance of law and order and civil amenities. All the activities pertaining to the handling of an off-site emergency are guided and coordinated from a pre-designated emergency response centre located outside the boundary of the nuclear facility. The information and broadcasting department of the district, in association with an authorised information officer, ensures the smooth flow of information to the media to avoid panic and spreading of rumours.