Nuclear emergency protection: How the population is protected in a nuclear emergency and what GRS does to render support

13.05.2020

© istockphoto.com/ josefkubes

If in the event of an accident in a nuclear power plant or in another event large quantities of radioactive substances are released into the environment or if there is a risk of that happening, various measures are taken which are summarised under the term emergency protection. The aim of these measures is to protect man and the environment as far as possible from the harmful effects of ionising radiation. Depending on the type of measures and the responsibility for their implementation, a distinction is made between on-site emergency preparedness and off-site emergency response.

On-site emergency preparedness

On-site emergency preparedness aims at preventing or minimising releases of radioactive materials into the environment. Following the accident at Fukushima, numerous measures were added to the existing precautions. For example, all German nuclear power plants today have additional mobile emergency power generators and pumps with which cooling of the reactor core can be maintained even in the event of a total loss of power supply and cooling. The licensees are responsible for the planning and implementation of on-site emergency preparedness measures.

Off-site emergency response

On the one hand, off-site emergency response comprises early protective measures that serve immediate hazard control. These include in particular disaster response measures. On the other hand, it also includes other measures aimed at longer-term protection against health risks.

Disaster response

Disaster response measures include above all:

  • sheltering – this is to prevent the intake of any released radioactive materials from the air into the body. As the walls of buildings provide a shield against ionising radiation, this also reduces the direct impact of this radiation. According to the Emergency Dose Level Ordinance, these measures are considered appropriate if an effective dose of 10 millisieverts could be expected for a person who would be staying outdoors for more than 7 days without any protective measures. A call to shelter would also be suitable if, in the event of an emergency in a nuclear power plant, the time until an expected release of radioactive materials into the environment is not sufficient to evacuate a specific area.
  • evacuation – this measure may be considered for areas where an effective dose to a person of 100 millisieverts or more could be expected if the person were to stay outdoors for more than 7 days and without protective measures.
  • iodine thyroid blocking (ITB) – this means the distribution and recommendation to take special iodine tablets. This is to prevent that the radioactive iodine that would be released into the environment in a nuclear power plant accident can the accumulate in the thyroid gland. Iodine thyroid blocking is recommended for people up to 45 years of age if it is to be expected that certain limits for the so-called organ dose of the thyroid gland will be reached. What is important for iodine thyroid blocking to be effective is that the tablets are only taken when recommended by the competent authorities.

This is to ensure that the effect of saturation of the thyroid gland is really at its maximum when the radioactive cloud with the radioactive iodine contamination moves over the corresponding area for which the intake was recommended. More information is provided by the https://www.jodblockade.de/en/ website hosted by the Federal Environment Ministry. The aforementioned disaster response measures are planned in advance for specific zones around each nuclear installation, also including zones extending into neighbouring countries. This does not mean that the respective measures must be taken in any case. Rather more, concrete plans are drawn up and appropriate resources are provided to be able to implement them if necessary. The definition of the planning zones and the corresponding measures are as follows:

  • In the case of nuclear power plants in power operation, the central zone extends up to 5 kilometres around the respective plant. Evacuations, the call to shelter and the implementation of iodine thyroid blocking are planned for this zone. It should be possible to complete both an evacuation and the distribution of iodine tablets in this zone within 6 hours of the alarm being raised.
  • The intermediate zone covers a radius of between 5 and 20 kilometres around the respective nuclear power plant. The plans are essentially the same as those for the central zone, but after the alarm has been raised, it must be possible to complete an evacuation after 24 hours at the latest, and a distribution of iodine tablets after 12 hours at the latest.
  • The outer zone ranges from 20 to 100 kilometres. The plans for this area are intended to ensure continuous monitoring of the radiological situation. In concrete terms, this means, above all, that the radioactivity in the environment will be monitored continuously and for a sufficient number of locations within the zone and that the resulting radiation exposure for the people living there will be determined. In addition, precautionary measures are taken to distribute iodine tablets and to call on people to shelter.

Further protection measures

The further measures of emergency protection concern various areas of life that may be affected by the emergency and mainly serve the longer-term protection against health risks. Some of these measures are aimed, for example, at preventing radioactive substances that have been released into the environment from entering the food chain. A major role in this respect is attributed to extensive measurements of radioactivity in the air, soil, food and drinking water. The results of these measurements then form the basis e.g. for excluding agricultural products from contaminated areas from being sold, excluding the use of land for agriculture, or making dietary recommendations. Measures may also deal with the handling of other contaminated products, objects, or other materials.

One of the objectives is to enable people to lead as normal a life as possible in areas with only minor contamination. To this end, appropriate rules may e.g. be laid down for the decontamination of buildings or roads and for waste and wastewater management.

Powers and responsibilities

The disaster response authorities of the Länder are responsible for the planning and implementation of disaster response measures. Within a Land, responsibility for certain measures is usually divided among individual municipalities or government districts, as these are best acquainted with the local conditions and as emergency services, such as the fire brigades, are part of the local administration.

In contrast, emergency protection in other areas of life is primarily coordinated by the federal government. To this end, the Federal Environment Ministry - supported by the Federal Office for Radiation Protection (BfS), which among other things measures radioactivity in the environment throughout Germany - evaluates the radiological situation and informs the authorities responsible for emergency response in the respective areas of life when a danger from ionising radiation has to be feared. The respective competent authority (e.g. the Federal Ministry of Food and Agriculture for the food sector) then ensures that appropriate measures are implemented, taking into account all other factors that play a role in the respective area of responsibility.  

Federal Radiological Situation Centre

To support the Federal Government and the Länder, the Federal Radiological Situation Centre (Radiologisches Lagezentrum – RLZ) is activated in cases where an accident or other event may have radiological consequences affecting a larger area or several Länder. Under the direction of the Federal Ministry for the Environment, the BfS and GRS evaluate all available information on the event and prepare forecasts on the further course and possible radiological consequences. For this purpose, GRS maintains its own emergency centre. The RLZ is also supported in performing its tasks by the Federal Office for Civil Protection and Disaster Assistance and the Federal Office for the Safety of Nuclear Waste Management.

Here, the decision support systems RODOS used by the BfS plays an important role in the assessment of the situation. This allows forecasts of the probable spread of radioactive contamination and the resulting radiation exposure of people in the affected areas. This is based on information on the type and quantity of radioactive materials that were or might be released in an accident - also known as the "source term" - and up-to-date results of measurements of environmental radioactivity as well as weather forecasts by the German Meteorological Service.

Work of GRS on off-site emergency response

It is in particular to support the Federal Ministry for the Environment that GRS experts deal with various aspects of emergency response. In addition to the GRS emergency centre, the planning, execution and evaluation of emergency exercises that are as close to reality as possible play a major role. All this needs to be based on the development of relevant scenarios. In addition to possible event sequences in nuclear power plants, scenarios for radiological emergencies in the field of transport and handling of radioactive materials as well as scenarios with a terrorist background are also considered here. Further tasks in this area are the continued development of computational programs such as the forecasting tool FaSTPro, which can be used to support decision-making in emergency situations, and the training of authority staff members.

A current focus is on work in connection with the implementation of the requirements of the Radiation Protection Act, which came into force in 2017. This includes supporting the Federal Environment Ministry in developing the General emergency response plan of the Federation (Section 98 Radiation Protection Act). For this plan, in which the emergency management system of the Federal Government and the Länder is concretised, strategies for the protection of the population and the emergency services are developed i.a. for a number of so-called reference scenarios. These are based, for example, on the recommendations of the Commission on Radiological Protection and international organisations or committees and on the results of international research projects.

GRS experts participate in the revision of a catalogue of measures for the preparation of the Special emergency response plans of the Federation (Section 99 Radiation Protection Act). The measures listed in this catalogue relate, for example, to drinking water supply, decontamination, and waste disposal, for which separate special emergency plans are now being prepared. The focus of the current work is on those measures that have not yet been explicitly described in the catalogue of measures for emergency protection. Based on the lessons learned from the Fukushima accident, GRS is also developing a program for the preparation of forecasts on the amount of waste that may arise as a consequence of certain accident scenarios.