Environmental Radiation Impact Assessment

Environmental radiation impact assessment – What Is It?

An Environmental Radiation Impact Assessment aims to evaluate the potential influence of magnetic fields generated by high-voltage transmission lines on the planned development site.

In general High-voltage (161 kV) and extra-high-voltage (400 kV) transmission lines are deployed across the country and are designed to transport electrical energy from generation units over long distances. This is done through substations, where the voltage is stepped down before reaching the distribution network and ultimately the areas of consumption.

These transmission lines have the potential to affect their surroundings due to the magnetic fields generated by the current they carry.

Important: When evaluating the impact of such power lines, it is essential to assess their potential impact and not just the current situation.

There are two key criteria that must be considered when determining the recommended safety distances

for a construction project involving populated areas (such as residential buildings, schools, office complexes, logistics centers, commercial zones, etc.) located near high-voltage or extra-high-voltage transmission lines:

Compliance with electrical safety and shock prevention regulations, typically based on national planning and construction codes.
Compliance with recommended magnetic field exposure limits, as defined by relevant health and environmental guidelines.

Electrical safety and shock prevention:

Safety distances from high-voltage and extra-high-voltage transmission lines are determined by national and regional regulations, and can vary significantly between jurisdictions. These clearances are primarily intended to protect against electrical shock hazards and ensure safe separation between power infrastructure and nearby structures.

In most cases, the required distance ranges from a few meters up to approximately 30 meters, depending on the voltage level and applicable standards.
Therefore, it is essential to consult local regulations and planning authorities to determine the specific clearance requirements for each project.

Magnetic Field Safety Distances – Based on Regulatory and Industry Guidelines:

Safety distances between high-voltage and extra-high-voltage transmission lines and populated areas such as residential buildings, schools, offices, and commercial zones.
A commonly used rule of thumb is to maintain a clearance of at least 50 meters from 161 kV lines and 60 meters from 400 kV lines for occupied buildings.
When these minimum distances cannot be maintained, a project-specific Magnetic Field Exposure Assessment (EMF risk survey) is strongly recommended.

It is important to understand that these distances are general and conservative, and do not necessarily reflect the actual magnetic field exposure potential—especially in cases where multiple circuits run along the same corridor. In such cases, cumulative exposure may extend far beyond standard limits.

A professional engineering-based EMF assessment provides a more accurate and reliable evaluation, taking into account project-specific parameters such as:

Transmission tower configuration
Conductor height and spacing
Conductor cross-section and ampacity
Power flow direction
Number of circuits and combined field effect

What to Do When Clearance Is Insufficient?

If a project’s layout cannot accommodate the recommended safety distances, several mitigation strategies can be considered:

Adjusting the building setback according to assessment results
Designating non-continuously occupied areas (e.g., parking, storage) within the field impact zone
Undergrounding (burial) of power lines in critical segments
Evaluating the feasibility of Active Magnetic Shielding System

Summary

When planning construction near high-voltage or extra-high-voltage transmission lines, it is essential to:

Meet minimum safety distances as required by local building and planning regulations
Ensure compliance with magnetic field exposure limits, based on accepted environmental and health standards, through a formal EMF exposure assessment conducted by a qualified radiation consultant.

A detailed exposure assessment provides reliable recommendations and supports safe, code-compliant, and cost-effective project development.
In case of uncertainty, it is advisable to delay further planning decisions until a formal and professional magnetic field exposure evaluation is completed.

What is an active magnetic shielding system?

An active magnetic shielding system is an electronic system that includes sensors and current loops that can monitor the magnetic field levels in a specific area and produce an opposing magnetic field.
What is the purpose of an active magnetic shielding system?

The purpose of an active magnetic shielding system is to reduce magnetic field levels resulting from external electrical infrastructure (such as power lines) located in proximity to the area in interest, so that ultimately the equivalent magnetic field levels will meet the regulatory and/or the client's requirements.
In what situations does an active shielding system solve a radiation problem?

An active shielding system provides a solution to two main situations: Situations in which the desired areas have magnetic field levels that exceed the required exposure values, and situations in which due to the proximity of a project to external electrical infrastructures there is difficulty in obtaining construction permits and approval from the authorities because of a potential for exposure deviations. Given that there is feasibility for installing such a system, then it will provide a solution in terms of magnetic field levels from the electrical infrastructures.
What are the benefits of an active protection system?

The first benefit of an active system is the solution itself - there are many cases for which no alternative solution can be found. For example, in the case of an existing structure near an overhead power line that cannot be modified in any way. Another advantage is in terms of costs, the cost of an active system is significantly cheaper than the costs of burying an overhead high voltage power line. There is also the advantage of schedules, planning and building an active protection system will usually take a few months compared to the schedules for burying a high voltage power line, which can be in the order of years. An active system will also maximize the project area, with an emphasis on the areas intended for continuous occupancy and without expropriation due to radiation levels.
In what situations is an active protection system less appropriate?

The design of an active system will be adapted and designed in accordance with the characteristics of the overhead power lines and in accordance with the project outline. The more complex the interface between the power lines and the structure (different distances and angles), the more complex the system will be and may not provide a complete solution. An active shielding system may be less suitable in the case of a changing energy flow direction regime between the circuits, or it may be complex to implement, which can affect the cost of installation. However, it may still be a possible solution.
How is it determined if an active shielding system is required?

As stated, an active shielding system is a solution to a radiation problem. Usually because of at least one of two scenarios: First scenario - the problem already exists according to measured values in the project area. Second scenario - the problem can arise according to a magnetic field exposure survey, i.e. a survey of high voltage lines carried out towards the project. The survey examines the feasibility of the voltage lines to affect the project area at various electricity consumption scenarios and not only according to the current consumption status.

Environmental Radiation Impact Assessment