Construction of Nuclear Power Plant using Concrete Material

A project of building a nuclear power plant generally requires extensive civil engineering work. The construction requirements for building nuclear plants' structures are more stringent than those involved in the conventional structure.

As of December 2019, 455 Nuclear Power Plant (NPP) units operate across 31 countries. These NPP reactors can be classified into different generic groups:

Generation 1: It consists of realtors built before 1970, and most of them are not in operation anymore

Generation 2: It consists of realtors constructed between 1970 and the end of the 90s, most of which are still in service.

Generation 3: It includes the advanced light-water reactors and other systems with inherent safety features that have been designed and constructed in the last two decades.

Generation 4: It includes the next-generation reactors and other systems to be designed and built two decades from now.

The evolution of reactors from one generation to the other has led to tremendous improvement in safety features.

An NPP involves complex civil engineering structures and components operating in demanding environments. It includes essential items of the structures, systems, and components (SSC) necessary for safe and reliable NPP operation. Concrete is the most widely used civil engineering building material in the nuclear industry because of its following advantages:

High-durability

Ability to withstand high-temperatures

Resistant to wind and water

Less production cost

Easy manufacturing process

Ability to mold to any desired shape

Easy availability of ingredients

Non-combustible

Effective soundproofing material

Shielding property against radiation

Which type of concrete material is used in the nuclear power plant?

In NPP, concrete mixes having different requirements are used based on density – low, high, and medium; strength –normal, moderate, and high; durability – low permeability, wear resistance, and more.

The essential ingredients such as coarse aggregates, fine aggregates, hydraulic cement and water were used for the conventional standard strength concrete (NSC) for construction usage. Hydration starts after mixing cement with water and cement paste, or hydrated cement paste (HCP) is produced. This paste serves as a binding agent that binds aggregates to work together as a composite material.

Structural concrete of various types, including heavy concrete, standard concrete and borated concrete, were manufactured in the early days in the construction of nuclear power plants. The primary ingredients – coarse aggregate, fine aggregate, cement, water mixing performed through the volumetric method. Strength was considered as the most vital parameter in mix proportion. In contrast, durability was believed to be directly proportional to concentration.

The composition of concrete has dramatically changed from the conventional method for the construction of Nuclear Power Plant as follows:

High-density concrete proves to be an excellent shielding material to be used in nuclear power reactors for protection against the hazard of nuclear radiation leakage.

Types of cement are much more elegant than before; their bulk chemistry and mineral characteristics have changed. So, their interaction with supplementary cementitious materials (SCMs) must be taken quantitatively into consideration.

SCM should be strongly encouraged to enhance concrete performance characteristics.

Characterization of SCM is paramount to ensure that it provides anticipated durability and new age properties.

Nuclear codes should not introduce arbitrary barriers to SCM use

The standard test method for potential alkali-silica reaction (ASR) must be adopted, which may aggravate due to the temperature, radiation, and moisture conditions that exist in nuclear power plants.

The behavior of irradiated concrete should be investigated. As the existing data is becoming outdated, so newer concretes and additives should be examined thoroughly.

Hence, civil and structural engineering teams play a vital role in performing analysis and design services for constructing nuclear power plants, including support of plant systems and components.

Judith Morrison is an expert in the field of industrial engineering and writes articles related to piping, civil, equipment engineering related articles.