Nuclear and Radiation Safety

The safety of nuclear installations, radioactive waste management facilities and radiation sources is ensured by design features, multi-level protection system and operational procedures.

Establishment of legislative and regulatory safety requirements and mechanisms for their control, training system, knowledge verification and maintaining competencies, introduction of authorization principle of nuclear energy use for peaceful purposes and safety culture philosophy at all levels are aimed primarily at preventing nuclear emergencies in the field of nuclear energy use. At the same time, despite the very low probability of emergencies, preparedness for response remains one of the fundamental principles of safe nuclear energy use.

Protecting the population from emergencies is the state function. A licensee, an employer, the regulatory body, public authorities have to develop measures in advance to ensure preparedness and response in the event of a nuclear or radiation emergency at the place of the event, and, if necessary, at the local, regional, national and international levels to reduce radiation risks in anticipated cases to insignificant level, and to minimize negative consequences for difficult-to-predict events negative by timely response.

Not all types of emergencies are accompanied by releases of radioactive substances that can cause harm to human health and the environment. Nuclear installation designs identify initiating events, end states and anticipated safety systems to limit radiation consequences for anticipated emergencies. The most dangerous consequences for humans and the environment can have events not envisaged by the design, which are accompanied by core control loss, self-sustained chain fission reaction or radiation source. Just to avoid the conditions for initiation of such unlikely events and their harmful consequences, measures to prevent failures, emergencies and safety systems malfunctions that could lead to loss of control are planned and implemented.

The three major accidents at nuclear power plants (Three Mile Island, USA: 1979; Chornobyl, USSR: 1986; Fukushima, Japan: 2011) were the result of a coincidence and a combination of several internal and external hazard factors. They have not only led to large-scale problems in the areas of health, environment, long-term needs for psychological, social and economic recovery, but have also boosted a revision of safety requirements, designing more reliable safety systems, elaboration of procedures for efficient response, including public awareness and maintaining public trust.

One of the tools to inform the public and mass media on assessment results of the impact of events on safety is the International Nuclear and Radiological Event Scale (INES).  

Level 4 to 7 events of on the INES scale are accidents that have an impact and require response measures outside sites of the installation. Level 1 to 3 events are classified as incidents or anomalies that affect safety. Classification of an event at the level 0 means that the impact of such an event on safety is insignificant.

More details are available in the INES User’s Manual on the IAEA web site.

For the last 20 years no operational events higher than level 1 (anomaly) according to the INES scale have been identified at the operating Ukrainian NPPs.

The defense-in-depth concept, which is the basis of the up-to-date reactor designs, is an integrity of consistent physical barriers on the way of radioactive substances and ionizing radiation spread and aims to prevent deviations from normal operating conditions, prevent accidents and limit their consequences.

If at least one of the four protection barriers remains intact, the goal to prevent the release of radioactivity into the environment is achieved. If, despite all preventive and emergency measures, the release cannot be avoided, emergency plans shall be put in place. Their purpose is to mitigate emergency consequences and to organize protection of the public and territories beyond the sites of nuclear installations.

To plan the response measures, the following classes of radiation accidents can be identified:

• industrial accident is a radiation accident, consequences of which do not extend beyond the facility and the territory of production premises, and only personnel can be affected by the emergency exposure;
• site accident is a radiation accident, consequences of which are limited to the territory of the industrial site of the facility, but require emergency preparedness of manpower and means of external organizations and carrying out intensified radiation monitoring;
• municipal accident (general) is a radiation accident, consequences of which go beyond the industrial site and can spread to the territory of the public residence and create risks in addition to natural external and internal exposure.

Nuclear facilities meet the basic nuclear safety criteria if the probability of emergencies that may require urgent measures to protect the public outside the nuclear facility control area is approximately 1 case out of 100,000 (or 1×10^-6) per year.

Restrictions on the use of land within the nuclear facility control area (within 2.5 — 3 km) and a prohibition on permanent residence and placement of social facilities, as well as other enterprises not related to nuclear facilities are implemented as a preventive measure.

 

Civil protection system in Ukraine

According to the Civil Protection Code of Ukraine, the Unified State Civil Protection System (USCPS) is a set of governing bodies, man power and means of central and local executive bodies, the Council of Ministers of the Autonomous Republic of Crimea, executive bodies of councils, enterprises, institutions and organizations ensuring implementation of the state policy in the field of civil protection.

Coordinating bodies are state, regional, and local commissions on the issues of man-induced and ecological safety and emergencies, emergency commissions of enterprises, institutions, organizations, and state, regional, local and facility special commissions established to coordinate the activities of central and local executive power authorities.

The USCPS components are functional subsystems established by central executive bodies in the corresponding areas of activity (i. e. the nuclear and radiation safety functional subsystem, safety of electric power and nuclear-industrial complexes functional subsystem, teaching preschool children, pupils and students to act in emergency situations functional subsystem etc), and territorial subsystems that are formed and operate within the administrative territorial units.

The nuclear and radiation safety functional subsystem was established by the SNRIU to protect personnel, public and territories from harmful effects of ionizing radiation by preventing nuclear and radiation accidents at nuclear power facilities and during transportation of radioactive materials, ensuring prompt response in case of emergencies, notification and keeping informed interested state authorities, the public (through the mass media), the IAEA Incident and Emergency Centre, competent authorities of other countries in the framework of international agreements in the case of transboundary transfer of radioactive substances.

The nuclear and radiation safety functional subsystem includes the State Nuclear Regulatory Inspectorate of Ukraine, management bodies and civil protection forces of economic entities subordinate to it and economic entities in the field of nuclear energy use. According to the law, it is the licensee (operating organization) who, after obtaining the relevant authorization of the SNRIU, bears full responsibility for radiation and physical protection and safety of a nuclear installation, radioactive waste management facility or other radiation sources.

The Provisions on the nuclear and radiation safety functional subsystem is available by the link.

Despite the very low probability of municipal/general accidents with the release of radioactive substances, the facility emergency plans of NPPs and other nuclear installations provide for the following emergency response measures within the Unified State Civil Protection System, namely:

• immediate notification of dispatching services and the state response body on an NPP operational event,
• prompt assessment and prediction of the situation development as a basis for issuing recommendations to local authorities to make decisions on introduction of urgent measures for radiation protection of public (shelter, iodine prophylaxis, evacuation, restriction of consumption of local food and water from open water reservoirs);
• intensified radiation monitoring in the control area and the observation area of nuclear installations.

The Emergency Preparedness and Response System of NNEGC “Energoatom” (NNEGC “Energoatom” EPRS) is a component of the functional subsystem “Safety of Electric Power and Nuclear Industrial Complexes” of the USCPS, which is being established by the Ministry of Energy of Ukraine.

In the event an NPP notifies on a municipal/general accident, the following shall be immediately activated:

• NPP emergency plan;
• emergency plan of the of NNEGC “Energoatom” Directorate;
• response plans of local and regional territorial subsystems of the unified state civil protection system, the territory of which belongs to the NPP observation area;
• response plans of other functional USCPS subsystems;
• and a state-level emergency response plan, which envisages establishing an interagency Headquarters that analyzes the situation and identifies actions for further emergency response at the state-level and elimination of an emergency consequences.

Efficiency and consistency of emergency plans is checked during emergency exercises and during the scheduled annual comprehensive inspections of the preparedness state to respond and ensure emergency measures in the event of threat or occurrence of radiation and nuclear accidents, other emergencies of man-induced and natural nature.

Specially trained emergency groups and teams are directly involved in elimination of the radiation accident consequences. Emergency kits of control and measuring devices and equipment, personal protective equipment, decontamination and sanitation means, tools and accessories, special equipment, vehicles and other emergency technical means for immediate use by emergency groups and crews in case of an emergency have been created and are maintained in a ready-to-use state at all NPPs.

A separated subdivision “Emergency and Technical Centre” (ETC) functions within the NNEGC “Energoatom” structure. The main tasks of ETC are to ensure permanent preparedness for rapid and efficient actions in case of radiation accidents at nuclear power plants and during radiation-hazardous cargo transportation taking into account Ukraine’s international obligations and IAEA safety requirements. The other ETC tasks are performance of special engineering activities including using robotics at nuclear energy facilities.

Functions and tasks of the state regulatory body, other central executive power bodies involved in elimination of the state-level emergency consequences are defined by the “State-Level Emergency Response Plan” approved by the Cabinet of Ministers of Ukraine dated No. 223 on 14 March 2018 (as amended according to the resolution of the Cabinet of Ministers No. 916 dated 06 November 2019).

Thus, in the event of an emergency, the NPP notifies and further informs functional and territorial USCPS subsystems, classifies emergencies, assesses the radiation situation, and predicts development and dynamics of radiation state changes. At the first stages of emergency response, it is the operator of the nuclear installation who acts as the main and only source of primary information. Decisions on introduction of radiation protection measures of the public based on information received from the operator on status of the nuclear facility and predicted estimation are made by local executive authorities.

The main objectives of the emergency response are to restore control over the situation and mitigate its consequences, save lives, prevent or minimize radiobiological consequences.

 

Notification and informing the public

One of the major factors affecting health is unjustified concern when people believe that they or their relatives have been adversely affected by radiation. Therefore, priority should be given to dissemination of timely, reliable and useful information for the public through trustworthy information sources. People residing rather far are sometimes more anxious and stressed by uncertainty than those living close to the event location.

Special warning systems are in place at nuclear power plants. The systems cover the territory of the industrial site, NPP control and surveillance areas within a radius of 30 km (Part 2, Article 53 of the Civil Protection Code of Ukraine; paras 12 and 13 of the Cabinet Resolution No. 733 dated 27 December 2017 “On Approval of the Provisions on Organization of Notification of the Threat of Occurrence or Occurrence of Emergencies and Communication in the Field of Civil Protection”).

Notification of the public in the NPP observation areas and areas of possible spread of radioactive contamination due to an NPP emergency is carried out by operational duty services of local executive bodies and local governments, which, in turn, receive initial notification from the NPP shift supervisor and/or NPP Director General.

Local executive bodies and local self-government bodies also perform functions of the territorial USCPS subsystem management authorities. It is their responsibility to provide the public with timely information on potential hazard of nuclear or radiation emergency in certain areas, nature of the hazards, warning and notification procedures and the measures to be taken in the event of such emergencies.

In case of an emergency, the territorial USCPS subsystems management bodies inform the public on the radiation situation, its changes and decide on the need for shelter, iodine prophylaxis, evacuation, restriction of consumption of agricultural products in the emergency impact area, organize their implementation in the established order.

The decision to implement urgent and long-term countermeasures to protect public health shall be taken as soon as possible in two main response phases:

• “acute” phase, when it comes to implementation of emergency measures immediately after the notification and initial classification of an emergency, and the conditions at the site are not yet fully under control, but delays in decision-making significantly affect effectiveness and usefulness of the implemented actions.
• “stabilization phase”, after the nuclear installation is returned to a controlled state, releases have stopped or the threat of their occurrence is prevented, when long-term measures need to be taken to overcome consequences of the accident.

During the “acute” phase, the risk of radiation exposure can be reduced by following the below recommendations:

• temporary sheltering inside buildings;
• self-evacuation, especially of children, pregnant women and nursing mothers;
• taking stable iodine drugs (only after relevant recommendations from the authorities);
• using personal respiratory protection means (respirators, cotton gauze bandages, dust cloth masks, etc.)
• meeting sanitary and hygienic rules.

The signal of prompt notification of the public on a nuclear or radiological accident at an NPP is the signal “ATTENTION TO ALL”, given by a klaxon, sirens of enterprises or signals of vehicles. This signal is a warning that an emergency has occurred and important information on it and required public actions will be transmitted soon. The broadcast takes place within 5 minutes after the sound signals. After having heard the signal “ATTENTION TO ALL”, it is required to:

1) indoors:

• turn on the TV, radio, smartphone or other device allowing to receive further messages;
• listen to information on the situation and recommendations for actions during an emergency;
• close the windows and move away from them as far as possible;
• cut off gas and water supply;
• collect a supply of necessary belongings, medicine, food and drinking water (in case of evacuation), put important documents in a protective package;
• listen to information and follow recommendations for further actions.

2) outdoors:

• if you do not have gadgets at hand, you need to get to the nearest institution or establishment where television, radio or other means of information are available;
• follow the recommendations on the procedure of actions as presented in para 1.

In all cases, it is necessary to act quickly, remain calm, not to panic, provide assistance to disabled people, children and the elderly.

In addition to NPPs, specific risks represent unforeseen events that may occur anywhere at any time involving radiation sources that are beyond regulatory control, have been lost, stolen or have never been controlled or lost control (e.g. satellites parts or other space crafts).

Radiation accidents can potentially occur where radiation materials are used, stored or transported. However, the impact of such accidents is limited to the equipment, buildings and sites where the activities are carried out and does not pose a threat to the public.

 

What to do in case of an NPP accident

Hazards for the public from accidents at nuclear installations can arise only as a result of significant releases of radioactive substances into the environment. Therefore, the key goal of emergency management is to prevent the release of significant amounts of radioactivity by implementing the concept of multi-barrier protection. If at least one of the four barriers remains intact, the release prevention goal is achieved. At the last, fifth barrier level, emergency plans shall be activated to mitigate the effects of emergencies.

Depending on the emergency nature, the release of radioactive materials can be short-term or long-term (with intervals) from a few hours to a week or more.

The following main pathways are the main ones to form the human exposure dose:

• external gamma radiation from a radioactive cloud;
• external gamma radiation from radioactive material falling from the air to the ground;
• external beta and gamma radiation due to radioactive contamination of buildings, vegetation, clothing, skin;
• internal exposure from inhalation of radioactive substances with air;
• internal exposure from radioactive substances when consuming water and food contaminated with radionuclides.

External and internal exposure can be avoided or reduced by introducing urgent protection measures: sheltering, evacuation and blockage of the thyroid gland with stable iodine, as well as limitation of consumption of contaminated local foodstuff and water from open water reservoirs.

To limit the exposure risk it is necessary to follow the following recommendations:

 Outdoors:

• leave the event location as soon as possible and move to a safe distance recommended by the authorities or those who first took over the response function;
• when staying on the ground do not undress, do not sit on the ground, do not smoke;
• before entering a premise be sure to wash shoes with water or wipe with a damp cloth, shake outer clothing and clean with a damp brush;
• take a shower, change clothes at the first opportunity;
• when leaving the room, be sure to use personal protective equipment (respirator, dust bandage, raincoat, rubber boots, etc.);
• exclude swimming in open water.

 Indoors:

• stay at home, in the office, in another premise if temporary shelter is recommended;
• seal the premise (close the windows, turn off the intake ventilation);
• perform daily wet cleaning of the premises, preferably with the use of detergents before receiving notification of stabilization or evacuation;
• strictly adhere to personal hygiene;
• do not use water from open sources and food, except in sealed packaging, protect food from dust;
• eat only indoors, before consuming food wash your hands thoroughly and rinse your mouth with a 0.5% solution of baking soda;
• control the radiation background (dose rate)
• listen carefully to notifications on development of the events and application of protection other response measures.

In all cases, it is necessary to follow recommendations of the competent authorities, attentively follow notifications via Internet, television and radio. Particular attention should be paid to the distance to the accident site and time spent close to the site; gamma radiation dose rate at the location according to the readings of personal dosimeter or monitoring networks. These data, as well as basic knowledge about the biological effects of radiation and assessments of trustworthy experts will help assessing how safe your situation is.

 

Main measures of radiation protection of the public

According to the up-to-date studies, international standards and methodologies of emergency preparedness and response, a severe accident with the nuclear fuel damage may require such urgent protection measures as evacuation and sheltering. These actions are combined with taking stable iodine. Urgent protection actions are supplemented with long-term ones, such as control of food stuff and water, relocation of the public from regions where the dose rate may lead to additional exposure during weeks and months due to radioactive fallout; decontamination of territory to reduce radioactive contamination level.

The methodology of the common European approach defines the following minimum zones and distances for planning protection measures:

• public evacuation should be prepared within 5 km around NPP, sheltering and thyroid gland blocking in radius up to 20 km;

• general strategy ensuring extension of the evacuation zone up to 20 km, sheltering and thyroid gland blocking up to 100 km shall be defined;

• radiation emergency monitoring and control of food stuff shall be planned at distances not less than 100 km with the possibility of extension up to 300 km;

Iodine prophylaxis

Iodine prophylaxis (iodine blockade) is the blocking of the human thyroid gland, which consists in the immediate introduction into the human body of a drug with stable iodine to prevent or reduce the absorption of radioactive iodine isotopes by the thyroid gland in the event of a radiation accident.

What concerns emergencies at nuclear installations, exposure of personnel and the public with radioactive iodine will be the dominant factor in the first hours of the accident.

Iodine prophylaxis should be used only in the event of a nuclear accident with depressurization of nuclear fuel accompanied by emissions of iodine-131 and cesium-137 isotopes. The idea of this measure is to ensure that human body does not suffer a lack of iodine, which can otherwise be filled with its radioactive isotope entering into the body through the respiratory system.

For other types of radiation accidents, the iodine prophylaxis is not relevant and does not protect against exposure to other radionuclides.

The maximum protection effect (reduction of the exposure dose of the thyroid gland by 100 times) can be achieved if iodine agents are taken before radioactive iodine enters the body or simultaneously with it.

Agents for iodine prophylaxis are potassium iodide (in pills); potassium iodate, in their absence, aqueous-alcoholic solution of iodine can be used.

According to the Ukrainian legislation, iodine prophylaxis is used if the expected absorbed exposure dose of the thyroid gland from the accumulated radioactive iodine can exceed 50 milligray for children or 200 milligray for adults in accordance with the regulations established by the central executive body, which ensures formation of state policy in health care area.

 

Doses of stable iodine for single use recommended by WHO

Age group	Mass of iodine, mg	Mass of potassium iodide (Kl), mg	Mass of potassium iodate (KlO3) ), mg	Fraction of a tablet containing 100 mg of iodine	Fraction of a tablet containing 50 mg of iodine
Adults and adolescents (over 12 years)	100	130	170	1	2
Children (3-12 years)	50	65	85	½	1
Infants (1 month – 3 years)	25	32	42	¼	½
Neonates (up to 1 month)	12,5	16	21	1/8	¼

Source: Iodine thyroid blocking. Guidelines for use in planning for and responding to radiological and nuclear emergencies. World Health Organization, 2017

For the public living within a radius of 10 km around the NPP, the local executive authorities distribute potassium iodide preparation in advance in the amount of the daily need. The remaining stocks of preparations are stored in pharmacies, kindergartens and educational institutions, medical institutions, military units, penitentiaries and other places designated by the authorities.

The procedure for receiving preparations is communicated to the public during the notification on a radiation accident. The preparations can be distributed by special teams at delivery points, this can be home delivery, free delivery to pharmacies, and so on. The first intake of potassium iodide should be carried out immediately upon receipt of the notification on the release of radioactive substances and relevant instructions of the authorities, preferably, before the radioactive release arrives or within the first six hours after the absorption of radioactive iodine isotopes by the thyroid gland.

“Procedure for Implementation of Urgent Measures of Iodine Prophylaxis among the Population of Ukraine in the Event of a Radiation Accident”, approved by the SNRIU Order of 8 November 2011. The Regulations on Iodine Prophylaxis in Case of the Radiation Accident, approved by the Oder of the Ministry of Health No. 408 dated 09 March 2021.

Sheltering

Sheltering can be implemented faster than evacuation and does not require resources other than timely notification and announcement of recommendations. This measure is most effective for several hours during the release, but loses its effectiveness after one or two days.

According to the Law “On Human Protection against Impact of Ionizing Radiation”, measures to shelter people are applied if during the first two weeks after the accident the expected total effective radiation dose may exceed 5 mSv.

Basic types of specially equipped protective structures are shelters, which are sealed structures protection against the effects of many natural disasters, accidents and catastrophes, radiation shelters, which have slightly less protective properties than sealed shelters, and dual-use structures. These are ground or underground structures that can be used for the main functional purpose and to protect the public from emergencies. People need to arrive at the shelter with personal protective equipment, a two-day food supply in a plastic bag and essentials.

Interactive maps of the civil protection protective structures in settlements and in the territories of administrative units are available on the official websites of the Main Departments of the State Emergency Service of Ukraine and local executive bodies.

                                                                                   

If it is not possible to take shelter in a specially equipped protective structure, it is necessary to stay in a building at the place of residence, work or temporary stay during the passage of the radioactive “cloud”, taking into account that wooden walls can reduce gamma radiation rate by two times, brick walls by ten times, basements with concrete roofing by 40-100 times. At the same time, it is necessary to follow official announcements and advices on further actions.

Evacuation

The Law of Ukraine defines that temporary evacuation of people shall be carried out if during the first two weeks after the accident the effective exposure dose can reach the level of 50 mSv. Timely and organized evacuation is an effective protection measure, but it brings discomfort to normal living conditions, is not always the best protection action and is used as an exceptional measure.

The public shall be notified of the time and procedure of evacuation by the management bodies of the territorial USCPS subsystem. In the conditions of radioactive contamination of the area, transport is delivered directly to entrances to protective structures and buildings, and people have to be boarded as soon as possible. During movement of the column, dose monitoring shall be performed.

Evacuation from the contaminated area shall be carried out in two stages. At the first stage, the public is transported to the boundaries of the contaminated zone. An interim evacuation point is organized there, registration, dose monitoring and decontamination of people being evacuated are carried out. After sanitation and decontamination of things, repeated dose monitoring shall be carried out and the evacuees are transported to the destination areas by “clean” transport at the second stage.

Evacuation is most effective measure if it can be completed before the release starts. If the release has started and is ongoing, it may also be effective, but the increased radiation risks of the evacuation conditions during long-term release should be taken into account. Evacuation is not recommended and will not have the expected effect if the release is over before its completion. Evacuation routes should always take into account wind direction and weather forecast.

The evacuation of the public after the Chornobyl accident started at 2:00 pm the next day, on 27 April 1986. By means of 1225 buses, 360 vehicles and 2 railway trains, 44,460 people were evacuated from the city of Pripyat within three hours (some inhabitants were evacuated using their private vehicles). The evacuation was carried out in two directions: most people were evacuated to Polissya Raion of Kyiv Oblast, a smaller part was placed in Ivankiv Raion. However, the evacuation organizers did not take into account the wind direction, which carried the radioactive cloud in western direction. Therefore, the residents of Pripyat, who were evacuated to Polissya Raion, received additional exposure doses. 

On 3 May 1986, 15 villages in 10 km area from the Chornobyl NPP (about 10,000 persons) were evacuated, by 7 May another 43 settlements (including Chornobyl), and by the end of the year 188 settlements in total had been relocated from the 30-kilometer zone, what constituted about 116 thousand people (including Pripyat). That was how the Chornobyl Exclusion Zone was formed.

An example of evacuation well in advance were the decisions and actions of Fukushima Prefecture in Japan in 2011.

 

FAQ

How one can learn about an accident?

• from mass media, social networks, mobile operators services;
• from official reports of the State emergency Service of Ukraine, State Nuclear Regulatory Inspectorate of Ukraine, nuclear operators on their official websites or from their statements to the mass media;
• from reports of local executive bodies, including alarm signals and loudspeakers.

 What measures should be taken to reduce the risk?

• leave the event scene as soon as possible and move to a safe distance recommended by the police and other authorities who were the first to take over the response function;
• follow recommendations of the competent authorities of the country of residence, messages via the Internet, TV;
• take a shower, change clothes at the first opportunity if the event caught you outdoors;
• stay at home, in the office, other premises, if temporary shelter is recommended;
• do not drink water from open sources and food other than hermetically sealed;
• take a stable iodine preparation or an alternatively recommended number of alcohol solution drops only in the case of the announcement of iodine prophylaxis!;
• close windows, turn off the intake ventilation, do wet cleaning before receiving a notification on stabilization of the situation or evacuation;
• help those who need it, remain calm and keep common sense;
• consult a family doctor if in doubt or anxiety.

Options to estimate that you and your relatives are safe and factors to be accounted:

• distance from the event epicentre or time spent close to the event place;
• gamma radiation dose rate at the location according to readings of personal dosimeter or monitoring networks;
• information received from competent authorities and prediction of the event development;
• expert assessments you trust;
• basic knowledge of the biological effects of radiation.

Always use verified information from reliable sources!

Uatom.org Editorial Board

General Information about radioactive sources

Discovery of radioactivity made by Antoine Henri Becquerel in 1896 has become a significant achievement. Up till now the radioactive materials are put to good effect in medicine, agriculture, heavy industry, electricity generation etc. However, despite the wide range of radioactivity applications in useful purposes, there is an opposite side to this discovery, that is, abusing ionising radiation may lead to burns, radiation sickness, and death, emergence of cancer, tumours, and genetic mutations. Ionising radiation source (IRS) (radioactive sources) is a physical object, except nuclear installations, containing a radioactive substance, or a technological device, which creates, or, under certain conditions, may create the ionising radiation. In order to ensure compliance with the allowable limits of radiation effects to personnel, public and environment, established by rules, regulations and standards on safety, there is a State regulatory control.

The radioactive sources, which are not under regulatory control, or have never been regulated, or were left without attendance, lost, placed in inappropriate location, transferred without proper permission from the State or stolen are called the “orphan sources”.

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”Orphan sources” means such IRS that are not covered by the State regulatory control due to the fact that they have never been under regulatory control, or because they were left, lost, placed inappropriately, stolen or transferred without proper formal permission.

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The problem with “orphan sources” lies in their potential hazard to public health and difficulty in their detection. Ionising radiation sources are normally stored in metal containers with thick walls, which, using the corresponding equipment, makes it difficult to identify the presence of a radioactive source inside. Moreover, they could be objects of various sizes and shapes, and, as a result, they are often become the items of interest for diverse population groups with a variety of purposes.

An “orphan source” falling into the hands of a regular citizen may lead to catastrophic consequences. An example of such situation may be the case of radioactive contamination occurred in 1987 in the town of Goiania, Brazil. A component of the radiotherapy unit containing the radioisotope Caesium-137, was put on the scrapheap by perpetrators after the robbery. After that, this source was found by a local citizen, whose mishandling with it had led to the spread of radioactive contamination, and, consequently, four people had died with radioactive contamination, while the area where this source was located would be unsuitable for life for the coming 300 years.

Prevention of the “orphan sources” emerging

With the account taken of the abovementioned information, it is obvious that there is a necessity of preventing the “orphan sources” from emerging. Ones of the basic preventive measures are:

• Ensure a permissive principle of the use of sources (i.e. a radioactive source may only be used by individuals or enterprises who have proved to the State that they are capable of ensuring safety and security of the source),
• Accountancy and control of radioactive sources.

Therefore, the use of nuclear installations and ionising radiation sources in Ukraine is based on a permissive principle. The State Nuclear Regulatory Inspectorate of Ukraine has the authority of issuing permits for each individual type of activity related to the use of radioactive material, in particular, a license for using an ionising radiation source (IRS).

According to the Law of Ukraine ”On licensing activity in the area of nuclear energy utilisation”, the State registration of sources of ionising radiation is mandatory, and, therefore, accountancy and control of location and movements of the sources are ensured. According to information voiced at the International Seminar “Orphan and vulnerable sources regulation. Experience and prospects of Ukraine”, held at the end of 2012 in Kiev, as of December 2012, the State IRS Register, where all the sources and operations with them are filed, has 12462 radioactive sources and 15838 generating devices registered. It should be noted, that according to the Provisions on the State Ionising Radiation Sources Register and the procedure of payment for services on their registration approved by the Resolution of the Cabinet of Ministers of Ukraine of 4 August, 1997, No. 847, the State IRS Register is the sole State system for accountancy and control of ionising radiation sources, the handling of which is not exempted from regulatory control and which manufactured on the territory of Ukraine or those sources brought in or took out through the State border, as well as the owners of these IRS, legal entities or individuals for whom IRS are formalised on the basis of the right of economic management or control, or being in their possession and use on other grounds. Significantly, among some 500 thousand ionising radiation sources in Ukraine, more than 450 thousand pieces have already been decommissioned and are now stored at the State facilities for radioactive waste management and accounted for in the State Radwaste Register.

In such a manner, since the fully functional system of the State regulation, including accountancy and control of the sources, has been established, a potential occurrence of orphan IRS is minimised.

Another preventive method is counteracting potential threat of IRS converted into the “orphan” category. The sources that may be abandoned are categorised as vulnerable. According to information presented at the International Seminar “Orphan and vulnerable sources regulation Experience and prospects of Ukraine”, held at the end of 2012 in Kiev, vulnerable sources are the radioactive sources, which presently are under control, but this control is not sufficient for ensuring continuous safety and security. In the first instance, it is those sources, which are no longer in use or of no use for the enterprises. The regulatory authority of Ukraine limits the terms of storage of such sources and requires that they be transferred to the specialised facilities, where such spent sources are provided with high level safety and security.

A particular hazard comes from those sources, which have been in ownership of enterprises that went bankrupt or that are financially instable, therefore, individually unable to handle the issue of transferring such sources to the specialised facilities. In order to resolve this issue there are international programmes underway with American and German partners. These programmes aimed at collecting the sources from sites and moving them safely to the specialised facilities. In the outcome, the substantial results have been achieved in implementing these programmes, and large numbers of sources have been collected.

However, there is a certain number of sources beyond regulatory control. One of the causes of such situation is that there were no mandatory requirements to control certain ionising radiation sources in the past when the less stringent requirements were established for control of certain types of sources. As of today, such approach has been changed radically, and the sources, which were outside regulatory control, are now subject to mandatory registration or licensing. Another cause is the loss of control over certain IRS due to the following reasons:

a. the source was lost;

b. the source was stolen;

c. the source was located in inappropriate place

Such sources have to be detected (searched for).

Searching for “orphan” sources

The issue of searching for “orphan” IRS is bulk large in Ukraine. Ukraine has two methods of searching for already “orphan” sources: administrative and physical.

The search for “orphan” IRS requires a systematic approach. In this context, the administrative method plays an important role. Its application envisages the search for information on the “orphan” sources, as well as holding inquiries that allows collecting the necessary information at the initial phase of building the system of detecting the “orphan” sources for its efficient functioning.

In Ukraine this method is not considered effective since historically the process of regulating the “orphan” sources in this country have been running on the regular basis, which made it practically impossible to loose information on locations of the discussed sources.

Therefore, in Ukraine more attention is paid to the physical search i.e. search for the sources by their physical characteristics: external appearance and radiation. This type of search takes a special place on the road to resolving the issues with “orphan” sources, since IRS are normally held in metal containers, they are often found in scrap metal. Moreover, there is a high probability of their consequent remelting, which may lead to a considerable radioactive contamination. Thus, it is this type of search that is more effective.

There are passive and active systems for the search of “orphan” IRS within the frame of physical search. The difference between these two systems is that the passive system envisages the search by installing radiation portal monitors in all the key points, such as: customs, ports, scrap metal management facilities, especially Iron & Steel Works, and border checkpoints. While the system of active search envisages the direct rummage of all suspicious sites with portable radiation monitors, and, at the same time, the additional methods could be applied, such as gamma aerial survey and vehicle gamma radiation survey. Regrettably, the active search requires a lot of expenditures, which Ukraine is unable to cover individually; therefore, the need arises to involve the international assistance. Due to economic problems worldwide it is difficult to obtain financial support, which hampers the active development of this system in Ukraine. Nevertheless, there is willingness in Ukraine to make the active search more effective, and it is planned to commence this process with inspecting the sites, which were used by the military and signed away for public use. Additionally, in order to achieve the desired goal, the SONNI new mobile radiological laboratory, equipped with gamma-detector, will be used in Ukraine.

It should be noted, that according to the conclusion of the “Green book” (consultancy in IRS safety in Ukraine of 01/03/2008) the active search is the most effective method of “major “cleanup” of the country’s territory” from the “orphan” IRS since the system of passive search works only if an “orphan” source reaches the point of passive control, but in case there is no movement, a source could only be detected through the active search.

Nevertheless, in this context, the important fact is that the passive search in Ukraine is represented by a multi-barrier system of control, which includes:

1. Radiation monitors and other means of radiation monitoring existing on the borders.
2. Radiation monitoring at enterprises. Currently, there is a tendency of growing number of detected sources, which were not accounted for earlier during the annual IRS inventory (performing the annual inventories is a regulatory requirement).
3. Radiation monitoring at scrap-yards. Today it is hard to say, to which extent this barrier may be considered effective, since there is no substantial activity observed in detecting the orphan sources by such facilities. The causes for this may be the following: the orphan sources really have not come into their view, or the enterprises chose not to accept the scrap metal from vehicles the background radiation of which exceeded the normal limits. According to the Resolution of the Cabinet of Ministers of Ukraine of 2 June, 2003, No. 813 , in case of detection of radioactive material in the course of border control, or environmental or radiation monitoring, financial liability for expenses, related to radioactive materials being in illicit trafficking, shall rest with the owner (user) of cargo, while in case of absence of the owner, the responsibility shall be placed upon the local power authorities. Unfortunately, the situation is being shaped up in a way so that local government authorities are often unable to tackle the discussed difficulties; therefore, in the long run an enterprise is forced to pay for disposal of a source. Such situation may provoke the latters to refuse accepting the cargo, which background radiation exceeds the normal limits, so that to avoid additional financial expenses. In the international practices there is an example of resolving such a dilemma – the Spanish protocol on cooperation in the area of radiological surveillance of the metallic products (ECE / TRANS / AC .10/2006/2). According to this document, a metal processing enterprise shall be exempted from payment for handling the detected “orphan” sources on the account of minor annual payments to the corresponding fund.
4. Radiation monitoring at iron and steel enterprises. According to the Order No. 183 of 18 November, 2011, No. 1321/20059 on approval of Licensing conditions for carrying out business activities on provision, processing, metallurgical processing of scrap metal of ferrous and non-ferrous metals, the experts of an enterprise shall ensure checking against explosion safety and obligatorily perform radiation monitoring of the scrap metal. However, despite of this, the iron and steel enterprises install portal monitors totally on a volunteer basis and perform monitoring as they do realise the hazards and material damage that could be inflicted by decontamination of all the equipment in case of radioactive contamination. Such barter trade is very effective.
5. Additional radiation monitoring of the scrap metal that is exported.

To summarise, it is worth mentioning that it is necessary to apply maximum effort, so that after all existing vulnerable and “orphan” sources have been collected, it would be possible to minimise the probable occurrence of new vulnerable or orphan radioactive sources. To this end, there are the State regulatory requirements, which must be complied with.

Requirements for the existing spent (vulnerable) sources:

The Ukrainian nuclear regulatory authority applies stringent enough requirements to the enterprises handling IRS: not to store the spent sources for longer than 6 months. If an enterprise fails to comply with this requirement, it may be penalised with the corresponding sanctions. If such sources have been converted into the radioactive waste category, the enterprises would then have to make the corresponding payments to the radwaste management fund. Experience has proven that it is unprofitable for the enterprises to keep such sources due to several factors: one the one hand, there is a pressure from the side of inspectors, who may issue fines in case the requirements are not complied with, on the other hand, there is an obligatory payments to the radwaste management fund should these sources are re-categorised as the radioactive waste.

Requirements to the newly purchased sources:

In this context there are two options for the enterprises purchasing a new source:

1. Pay to the radwaste management fund straightaway; while, upon expiry of the source’s service life, a specialised department will individually and free of charge take this source away for disposal.
2. Conclude an agreement with the supplier on its obligation to take the source back after it has been used.

Today Ukraine is implementing the best international practices in the area of “orphan” sources management. At the same time, it is important to understand that a large number of the found sources is not a reflection of the fact that the system of control is ineffective, quite the opposite, it is because there is an effective search system in place. Moreover, Ukraine reports to the IAEA of each and every found source, the country has chosen straightforward and transparent policy in the issue: we always report when we find and make our results available. Therefore, it is possible to minimise the problem, it is also possible to ensure control, but it is not possible to fully prevent the occurrence of vulnerable and orphan sources, that it is why it is required to have an efficient system for the effective response.

Moreover, it should be emphasised, that illicit possession of a source is very unprofitable. Selling it for big money is a myth. If found guilty, a sentence may be of up to 8 years in prison.

Recommendations for Population on Radiation Protection during Diagnostic Procedures with the Use of Radiation Sources

Throughout the life each human being undergoes dozen diagnostic and, if necessary, therapeutic tests and measurements with the use of ionizing radiation sources. These medical exposure procedures are prescribed by the doctor as planned ones and carried out in medical institutions. Often people diagnose their ailments by means of the X-ray equipment (mammograph, photofluorographic equipment, dental X-ray units, computerized tomographs, orthopantomographs, angiographs, etc.).

Annually each human being undergoes minimum one X-ray diagnostic procedure. As a rule these procedures are necessary for correct diagnosis of ailments and cancer. At the same time, such procedures have certain risks of stochastic effects caused by the exposure. It is necessary to pay special attention to the avoidance of the wrongful prescription of medical exposure or failure to ensure patient radiation protection during these procedures.

Worldwide the special attention is paid to the investigation and optimization of the doses for the patients at diagnostic procedures to prevent negative consequences of medical exposure.

What should the patient know?

The list of the most popular questions to the SNRIU made by population:

Is the X-ray diagnostics dangerous?

The radiation dose at X-ray diagnostics is small. But one can see the increase of the cancer risks in view of the repetition frequency of such risks from year to year. The patient takes comparatively high radiation dose as a result of the diagnostics at computerized tomographs, angiographs and due to the interventional procedures that can cause cancer.

Angiographer

Intervention procedures

Computer tomography

Mobile X-ray system with C-arch Radius-R12 AFG

What does the “radiation dose” mean?

The effective dose, specified by means of corresponding calculations with the use of the value of absorbed dose to the member of the body and indicated in mSv (10-3 Sv), is used to assess possible potential risks to the human being health.

Is there any difference between medical and natural exposure?

Each human being undergoes natural exposure due to the cosmic rays (space radiation), earth, food and our body radiation. This radiation (γ-radiation) is equal to that X-rays taken during medical diagnostics. The annual natural background radiation dose for the human being makes 1-3 mSv (2,4 mSv in a mean) depending on the region where the human being lives. On the Earth, one can find places where human being radiation dose can exceed 10 mSv for a year.

Whether all X-ray diagnostic procedures are characterized by high radiation doses or no?

No. The different types of X -ray diagnostic procedures cause different radiation doses. In average this dose makes 0,2 mSv. In comparison to natural radiation, this dose is low.

The ranges of the radiation dose standard values for standard X-ray diagnostics are given below in comparison to the natural background radiation:

Whether X-ray doses comply with ranges specified in the Table or not?

Not always. Patient actual dose depends on many factors, in particular: equipment technical state, medical staff qualification, peculiarities of medical diagnostics, etc. The continuous improvement of medical equipment means that, most likely, the standard doses should undergo changes. Any X-ray diagnostics should be directed to minimization of radiation burden and to the use of more reduced impact diagnostics and of protective and other means of radiation burden minimization.

X-ray diagnostic complex “Medix”

Mammograph

X-ray system based on the high-frequency inverter EVA-HF 750

X-ray diagnostic complex (type РУМ-20)

Why the mammography is not recommended to the young women as screening?

The mammography is not an effective method of screening for asymptomic young women (up to 40 years old) to reveal breast cancer. The screening (mammography) is applicable for the women that relate to the high-risk patient group (for example, for the women whose relatives had the breast cancer in young age or have another clinical signs of cancer). For such group of women the screening is justified from the point of view of radiation protection since they undergo the high risk of breast cancer in old age.

After its operation in the reactor core, spent nuclear fuel is unloaded to the reactor cooling pools to be stored for 4 to 5 years to decrease residual energy release. Residual energy release is a process induced by radioactive decay of fission products.

After cooling in the reactor pools, spent fuel is loaded into special containers that ensure its safety in transportation and is sent to a spent fuel storage facility. The current state of science and technology does not permit the final conclusions on further spent fuel management. Hence, there are several approaches to spent fuel management in the world:

1. Processing. There are two types of processing – local or in other countries:

• local processing provides for spent fuel processing to obtain components and substances whose use is economically sound (Great Britain, India, Russia, France, Japan);
• processing in other countries provides for processing of spent fuel and return of high-level waste to the owner country (Bulgaria, the Netherlands, Switzerland);

2. Disposal is intended for spent fuel cooling and burial in deep geological formations (USA, Finland, Sweden).

3. Deferred decision is intended for long-term spent fuel storage that permits a decision on subsequent spent fuel management taking into account future technologies and economic factors. The deferred decision is used by Argentina, Denmark, Spain, Canada, Lithuania, Germany, Norway, South Korea, Poland, Slovakia, Hungary, Czech Republic, and Croatia.

According to design decisions for WWER-1000 NPPs (there are 13 operating units of WWER-1000 type in Ukraine), spent fuel was to be transported to a stationary storage facility to Russia.

However, it became evident, even in the former USSR, that the storage facility had limited capacities, could not be expanded, a spent fuel processing facility could not be constructed in the immediate future and that would significantly affect NPP performance.

Estimates showed that the Zaporizhzhya NPP would be under the most pressing conditions requiring shutdown of the units.

In this connection, the USSR Ministry of Energy issued Order No. 361 of 6 October 1988 to approve the design for the second stage of the Zaporizhzhya NPP, including a spent fuel storage facility.

After the USSR broke up, spent fuel ceased to be transported to Russia in 1993-1995. The Zaporizhzhya NPP analyzed the dynamics of filling the cooling ponds and started a search for alternatives for spent fuel storage in 1993.

In view of the economic part, possibility to purchase components from Ukrainian producers, minimize modernization efforts at power units and use available handling equipment, the project proposed by the US Duke Engineering & Services Inc. (DES), which had obtained a license of the US NRC at that time, was chosen.

In 1996, the Zaporizhzhya NPP started implementing the spent fuel dry storage project.

The project is based on dry ventilated storage casks (VSC) for vertical storage of spent fuel assemblies (SFA). Dry storage is efficient since SFAs are stored in the cooling pool for no less than 5 years where their residual energy release and radioactivity greatly decrease. This fuel can safely be stored on-site in dry VSCs that effectively remove heat from SFAs and ensure adequate shielding from radiation for personnel, the public and the environment.

Prior to commissioning of the dry spent fuel storage facility (DSFSF), the working design, DSFSF Safety Analysis Report and DSFSF Environmental Impact Assessment were developed and reviewed, ecological reviews were carried out and pre-commissioning tests were performed at Zaporizhzhya-1–6.

Following an analysis of pre-commissioning tests and documentation submitted by the Zaporizhzhya NPP, the NAEK Energoatom was granted a license for trial commercial operation of the nuclear installation on 16 July 2001.

Zaporizhzhya DSFSF site. First containers

On 24 August 2001, the first WWER VSC was placed on the DSFSF site. Since then the trial commercial operation of the DSFSF has stated. On 10 September 2004, the Zaporizhzhya NPP obtained a license for operation of the Zaporizhzhya NPP nuclear installation including the DSFSF.

It should individually be noted that the Zaporizhzhya NPP developed more than 270 documents within the licensing procedure. More than 50 reviews and assessments were conducted.

The spent fuel dry storage system used at the Zaporizhzhya NPP is conditionally divided into three areas:

• loading area;
• transportation area;
• storage area.

The loading area is intended for the safe loading of SFAs into a basket, handling operations in sealing, drainage, vacuum drying and filling of a multi-place sealed basket with helium and loading of the basket into a ventilated concrete cask. The loading area is located directly in reactor compartments.

Available handling equipment is used for DSFSF components.

The transportation area is a network of paths for WWER VCS transportation to the storage area with a storage cask transporter.

The storage area is intended for safe storage of WWER VSCs for no less than 50 years. The storage area includes the storage site formed with a reinforced concrete plate for WWER VSCs. The storage area has its own physical protection fence.

The dry spent fuel storage system is designed for 380 ventilated storage casks that can hold more than 9000 SFAs.

Loading area

Storage area

The storage site can house spent fuel for the entire operational period of the Zaporizhzhya NPP. The license permits storage of spent fuel only from the Zaporizhzhya NPP.

Transportation area

The main components of the dry spent fuel storage system are:

• multi-assembly sealed basket (MSB);
• transfer cask (TC);
• ventilated concrete cask (VCC);
• ventilated storage cask (WWER-VSC), including SFA in MSB placed into VCC.

To ensure safe operation of the dry spent fuel storage system, the ventilated storage casks, equipment used and buildings and structures of the storage system are continuously monitored.

Regular radiation monitoring is conducted in compliance with regulatory and production documentation at all handling and transportation stages, beginning from spent fuel transfer for storage at the DSFSF and to storage on the DSFSF site.

The WWER VSCs are placed for storage on the DSFSF site under individual SNRCU permits. Each cask is placed so as to minimize the dose rate at the site boundaries and to minimize radiation on construction personnel during installation and construction. After the shielding structure outside the site perimeter to ensure radiation protection of personnel, the public and the environment had been completed in December 2005, it was no longer needed to calculate the location of WWER VSCs on the DSFSF site.

For information:

The gamma dose rate at reference points at a distance of 50 meters from the site external fence is 0.11-0.12 µSv/h (11-12 µR/h), which corresponds to background radiation.

Radiation monitoring of samples of well water, atmospheric precipitations and atmospheric air for the entire operational period shows that the content of radionuclides in the DSFSF area corresponds to the background and global contamination level.

The radiation state around the casks is generally stable. Since spent fuel loaded into the casks has different characteristics, the total dose rate and neutron radiation from the center of inlet ventilation ducts varies from 13.4 to 155.9 µSv/g in casks. The neutron dose rate from the VSC lateral surface is detected at no more than one meter. The absence of radioactive contamination, inert gases and aerosols confirms that the casks are hermetically sealed.

Radiation monitoring on the DSFSF site established that maximally permissible values were not exceeded.

Dose analysis, which was carried out after WWER VSCs were loaded and stored on site, showed that administrative process levels of external (15 mSv/y) and internal (3700 Bq/y) exposure were not exceeded.

Visual examination and inspection of the WWER VSC outer surface showed that there were no inadmissible defects in concrete for the entire DSFSF operation.

Plugging of inlet and outlet WWER VSC ventilation channels was not observed during the entire DSFSF operational period.
Indirect parameters, such as the difference between the air temperature at the WWER VSC ventilation outlets and ambient temperature, are used to monitor the state of fuel stored at the DSFSF.

Temperature monitoring over the entire DSFSF operational period has shown that the maximum difference between the air temperature at the ventilation outlets and ambient temperature was 59 °C for WWER VSC No. 73, which is lower than normal operation limit 61°C justified in SAR.

Spent fuel of the Rivne, Khmelnitsky and South Ukraine NPPs is shipped to Russia. WWER-1000 spent fuel is sent for storage and WWER-440 spent fuel (Rivne-1, 2) for processing.

Sources:

1. The State Nuclear Regulatory Committee of Ukraine. Nuclear and Radiation Safety in Ukraine. Annual Report 2009/
2. http://www.npp.zp.ua/