As a routine part of the Ministry of Defence's and Plymouth City Council’s contingency planning, a one-day nuclear accident response exercise will take place on Wednesday.

Codenamed Exercise Short Sermon, the day is designed to test the procedures in place for dealing with a nuclear reactor accident involving a nuclear-powered submarine at Devonport Naval Base.

During the day personnel from approximately 27 agencies will be responding and playing at operational, tactical and strategic levels in Plymouth, Truro and Exeter.

 As part of the exercise a small number of non-essential personnel working in the Naval Base around the areas of 8, 9 and 10 Wharves will be required to take shelter or be evacuated to pre-designated shelter stations within the Base. Members of the public outside the Naval Base will not be affected or required to take any action.

Part of the exercise will include the distribution of simulated potassium iodate tablets in selected areas outside the Devonport site and this is achieved by teams of Royal Navy personnel delivering notices through letter boxes.

The exact areas involved in this part of the exercise will depend on weather conditions as outlined by the exercise directors and will not be known by the exercise players until the day. If members of the public receive notices through leir letter boxes there is no need for them to take any action.

The Naval Base Captain Safety, Captain Steve French stressed: "The Devonport site has a good nuclear safety record. In over 50 years of operations there has never been a reactor accident involving a Royal Navy nuclear-powered submarine which has required these emergency arrangements. Nevertheless, the Ministry of Defence, Babcock and Plymouth City Council have, in accordance with UK legislation developed detailed plans to ensure a swift and effective response to such an accident in Plymouth.

The purpose of the Short Sermon exercise is for the Ministry of Defence and Babcock to demonstrate to the independent regulatory bodies that, if ever called upon, the site has the necessary plans and resources while testing the broader off site multi-agency nuclear emergency arrangements."

Tracey Lee, Plymouth City Council's Chief Executive, said: "The exercise will be a very thorough test of Plymouth City Council’s multi-agency nuclear accident response plan. With around 27 agencies taking part this is a big exercise for all concerned and will assess how we all work together to protect and support Plymouth residents in the event of a major emergency."

Devon and Cornwall Assistant Chief Constable Andy Bickley, who will be the police and overall incident commander for the exercise, said: “Incidents like the one involved in this exercise are extremely rare, but we have to plan and ensure we are ready to launch a multi-agency response.

”Although we plan for this kind of extreme event, the real benefit comes from learning and practising how we respond as a co-ordinated group to more likely scenarios such as bad weather or an aircraft crash, for example.

“I’m confident the extensive planning that has been put in will make Short Sermon a success and Plymouth a safer place as a result.”

Alongside the Ministry of Defence, agencies participating include; Plymouth City Council; Cornwall Council; Devon and Cornwall Police; Devon and Somerset Fire and Rescue Service; South West Ambulance Service Trust; NHS England; South West Water; The Highways Agency; British Transport Police; Environment Agency; The Health Protection Agency; Met Office and the Department for Energy & Climate Change Radiation Information Monitoring Network.