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Nuclear

NB Power has one nuclear generating station - the Point Lepreau Generating Station which safely and reliably generates electricity. The 635 MW unit, commissioned in 1983, was the first CANDU-6 to begin commercial operation.

Nuclear safety is the primary focus of station activities. CANDU is an established Canadian technology with an excellent nuclear safety record, and Point Lepreau is a safe working environment. The station has exceeded one million person-hours without a lost-time accident on three occasions.

How CANDU 6 Works

The CANDU reactor uses natural uranium fuel and heavy water (known as D2o). Heavy water is used as both moderator and coolant (the moderator and coolant are two separate systems). Heavy water is very similar to ordinary water, except that it is slightly heavier due to the existence of an extra neutron in the hydrogen atom that form a part of a water molecule. CANDU reactors use heavy water to moderate the fission process.

 

 

In simple terms, fission occurs when a neutron strikes a particular isotope of uranium atom, called Uranium-235 creating the unstable element of Uranium-236. The extra neutron results in the U-236 atom splitting two fragments and releases other neutrons, energy and radiation. After moderation, the released neutrons go on to cause further fission and the cycle is repeated.

There are 380 fuel channels in the CANDU-6 reactor each containing 12 uranium fuel bundles. The uranium fuel bundle weighs about 20kg. Each bundle stays in the reactor between six months to one year. Through each fuel channel heavy water of the primary heat transport system flows to pick up the heat released by the fission in the fuel. This system called the heat transport system, takes this heat energy to the boilers where it is used to heat up and boil ordinary water to generate steam which in turn drive the turbine and generate electricty.

The nuclear reactor is housed in a concrete containment building 42 meters tall with 1.2 metre thick walls. The containment system consists of pre-stressed, post-tensioned concrete structure, an automatically initiated dousing system, local building coolers, two airlocks and a filtered air discharge system.

Reactor Building