As one of Britain’s busiest ports, Southampton may be visited by nuclear-powered vessels - and now the council has issued its latest advice on what to do in an event of an emergency.

Southampton was visited by HMS Tireless in 2012 – a Devon-based nuclear submarine – and HMS Astute in 2011, with the berth located at Dock Gate 4.

In the event of a radiation emergency in the city, Southampton City Council is required by law to have a ‘Reactor Emergency Plan’ in place.

A leaflet published by the council said: “If an incident occurs, it’s unlikely it would affect people more than half a kilometre (500 yards) from the vessel.

“The design of nuclear-powered vessels means that an emergency involving a vessel’s reactor is extremely unlikely. However, if the reactor on board a vessel suffers a serious problem and begins to leak, radioactive particles might escape into the air.

“There is no possibility of a ‘nuclear bomb’ type explosion.”

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Businesses and homes located within 1.5km radius of the submarine berth have been issued information letters from the council.

The leaflet added the main risk to the public would be if “radioactive particles were released into the air.”

It said: “Usually, all radioactive material would be contained in the submarine or ship.

“In extreme circumstances it is possible it is possible that some of the radioactive material could escape and affect areas close to the vessel or downwind of it.

“The main risk to the public would be if very tiny radioactive particles were released into the air.

“They might be carried by wind and could settle on people or objects that people are in contact with.

“These tiny particles are unstable and give off radiation.

“In these circumstances you could be exposed to radioactive particles by inhaling contaminated air or grass, having contact with contaminated surfaces, eating or drinking contaminated food or water, and direct exposure from particles as they are blown along in a ‘plume.’”

In the event of a radiation emergency the council has issued a four-point plan – secure your premises, go home/leave the area, tune in (listed and watch for announcements), stay tuned.