Table of Contents
Reactor Core
Reactor Core Components
The reactor core is where the magic (nuclear fission) happens to create energy. A reactor core is comprised of 4 basic systems and components:
These components are usually contained in a strong steel reactor pressure vessel (RPV). Alternatively, the fuel itself can be held within a RPV. Combined with fuel cladding, these thick steel tubes can keep the nuclear fuel contained when the reactor operates, this barrier is key to keep the radioactive material out of the environment.
The configuration of reactor cores can differ between reactor type, for a deep dive into these take a look at the various knowledge hub pages on different reactors!
Materials and Manufacturing
There are many material challenges that need to be considered when designing a reactor, these include:
High Pressure and Temperature
Corrosion
Radiation Damage
Because of this, the materials selected for the various components of a reactor are not done so randomly, each was chosen for certain applications.
A great example of this are PWRs. These reactors use a RPV specifically to contain the 4 components mentioned earlier. The body of this cylindrical vessel is built using high-quality low-allow carbon steel and any aspects of such that come into contact with the coolant are clad with at least 3-10mm of austenitic (corrosion resistant) stainless steel to prevent corrosion. Low-carbon steel has a relatively low cost, has properties acceptable for many applications and is malleable. These advantages are why it is the most common form of steel.
The image shows a RPV being installed in the reactor cavity, it’s hard to comprehend how big it is!
Safety Features and Emergency Protocols
Safety is at the forefront of every reactor design; the aim of safety systems is to prevent and mitigate the impact of accidents or abnormal conditions within a nuclear reactor.
The main safety concern for any reactor is the possibility of uncontrolled radioactive release and off-site radiation exposure. Due to accidents such as at Fukushima, we have a better understanding of the science of the material in a reactor core under extreme conditions, more specifically, a mix of a core melt down and a containment breach can cause major issues.
An example of one of the many systems in place to prevent this is the Emergency Core Cooling System (ECCS), this system is put in place to safely remove residual heat in the case of an emergency, such as loss of coolant in a reactor.
Rebecca Horrocks
The Nuclear Power Plant, Simopt – Courtesy of Energy Encyclopaedia & ČEZ, a.s.
Fuel Assembly, Simopt – Courtesy of Energy Encyclopaedia
Moderator, Simopt – Courtesy of Energy Encyclopaedia
Absorber, Simopt – Courtesy of Energy Encyclopaedia
