Radioactive Pollution

Radioactive Pollution, Monitoring & Safety

Nuclear Berths at Diego Garcia

Two alongside and one lagoon anchorage berth for nuclear powered vessels and submarines are available at Diego Garcia. These are designated as 'Operational Berths' by the UK Ministry of Defence, and nuclear work is generally not permitted. However, it may be undertaken if adequate justification is given and the express permission of the MOD and formal regulatory consent is given.

There have been no visits to Diego Garcia by UK Nuclear Powered Warships in the 5 year period (May 2007 - May 2012). However, submarines from the US 5th fleet call regularly for crew changes and repairs.

A Nuclear Accident Response (NAR) exercise is required at least every 3 years (Defence Nuclear Accident Response JSP471.pdf) as part of the contingency planning when these berths are used by nuclear powered vessels of the Royal Navy, US or French navies.

The last recorded exercise was in April 2011 as a Level 1 exercise - a test of the operator's emergency response arrangements. An earlier exercise in 2006 is detailed in Defence Nuclear Safety Regulator Exercise Indian Footprint-2006.pdf), this was only a table top exercise and guided walk through of the facilities.

Monitoring

The UK Ministry of Defence conducts surveys at all its operational berths worldwide. At Diego Garcia these are normally conducted every 5 years. There was a survey in September 2006 and again in July 2010. The July 2010 survey was brought forward from 2011 to perform a baseline survey prior to increased use of the berth. The next survey will be due in 2015. The results of the surveys are available in the following publications:

• Marine Environmental Radioactivity Surveys at Nuclear Submarine Berths 2006. ISBN No 978 0 11 773075.
• Marine Environmental Radioactivity Surveys at Nuclear Submarine Berths 2010 (includes 2007, 2008, 2009 and 2010 reports) ISBN No 978 0 11 7731066.

The 2010 survey report concluded that:

• A marine environmental radioactivity survey of the Operational Berth and surrounding area at Diego Garcia was carried out by Dstl in July 2010. Biota samples were not available for collection.
• The calculated gamma dose rates are consistent with the natural background levels recorded previously at Diego Garcia. No Co-60 or other man-made radionuclides were detected above the limit of detection in any of the 22 inter-tidal sediment samples analysed.
• No Co-60 or other man-made radionuclides were detected above the limit of detection in any of the 10 underwater sediment samples analysed.
• No Co-60 or other man-made radionuclides were detected above the limit of detection in any of the 6 samples analysed.
• The results are consistent with those which have been recorded previously at Diego Garcia and indicate that there is no detectable radioactive contamination associated with the operation of nuclear powered vessels.

The US Navy confirmed in Jan 2010 that it does not conduct any radionuclide monitoring in the Diego Garcia lagoon or territorial waters.

USS Emory S Land - nuclear submarine support ship

On 14 Aug 2010, the submarine tender, the USS Emory S Land arrived at Diego Garcia supposedly on permanent station to support and maintain the US 5th Fleet nuclear submarines and surface vessels.

Previously, the Emory S Land had been based at the US nuclear submarine base at La Maddalena, Sardinia. That base was closed in 2008 following an accident involving the nuclear submarine, USS Hartford, which went aground while performing routine manouevres, and the discovery of radionuclide pollution in the surrounding National Marine Park (Aumento et al. 2005). The radioactivity was suggested to be due to losses of minute quantities of radionuclides during the servicing of the submarines.

In pressing for the closure of the base in 2005, the Governor of Sardinia commented that "repairing and resupplying nuclear subs in a pristine area of national parks is dangerously inappropriate".

However, in November 2011 the Emory S Land was 'temporarily' moved to Guam to replace the USS Frank Cable which had returned to the US for a refit - see http://www.c7f.navy.mil/news/2012/01-January/010.htm). It would not appear to have returned again to Diego Garcia after this deployment.

What are SSGN nuclear submarines?

SSGNs are converted Ohio-class Trident ballistic-missile carrying boats, retired from their old job under the terms of strategic arms-limitation treaties. The US Navy saw no reason to get rid of the submarines which were still operational, and the removal of the Tridents left them with plenty of room for other things.

The rebuilt vessels can nowadays carry 66 elite special-forces frogmen, who will typically be Navy SEALs or possibly members of the new US Marines MARSOC outfit. Some reports suggest that up to 102 underwater warriors may be able to cram in for short periods. The subs have a "dry hangar", an underwater docking bay allowing the frogmen to deploy from their mother ship aboard SEAL Delivery Vehicles (SDVs), minisubs which can carry them in to enemy coastlines.

One variant of the SDV is said to be armed with its own torpedoes. There has also been some suggestion that the Advanced SEAL Delivery System (ASDS) might deploy from the SSGNs. The ASDS is a larger, enclosed mini-sub which can carry SEALs in warm dry conditions. However, reports suggest that the ASDS programme has hit problems; it may be that only a single prototype craft will be available.

The SSGNs also carry up to 154 Tactical Tomahawks which can strike locations a thousand miles inland.

References:

Aumento,F, Le Donne,K., Eroe,K. (2005) Transuranium radionuclide pollution in the waters of the La Maddalena National Marine Park. Journal of Environmental Radioactivity. 82:81-93

Davidson,A. & Sunley,L. (2008) Marine Environmental Radioactivity Surveys at Nuclear Submarine Berths 2006. The Stationary Office, London. 93pp