The exercise was carried out to test emergency procedures in the event of an accident involving radioactive materials.
Electronics giant Hitachi has announced it will buy nuclear power project Horizon, which includes a plan to build a new plant on Anglesey.
The new Welsh Secretary David Jones will pledge his support for a new nuclear power station on a visit to Wylfa on Anglesey.
Japanese electronics giant Hitachi is to buy the nuclear power project Horizon which includes building a new plant on Anglesey.
Hitachi says between five and six thousand jobs could be created during construction and a thousand permanent posts when it's up and running. It says that'll be in the first half of the 2020s.
A French company has confirmed it is interested in taking over the Horizon scheme, that had been expected to lead to the development of a 'Wylfa B' nuclear power station on Anglesey.
Horizon owners E.on and RWE npower withdrew in March, citing cost overruns in other projects in Europe.
The news came as blow to the island, since the project was due to lead to the creation of 5,000 during its construction.
Nuclear group Areva has responded to a report in the Financial Times, stating it now plans to bid for Horizon venture, which also includes a site at Oldbury in Gloucestershire
Areva Chief Executive Luc Oursel told the paper that the bid would probablybe a partnership with a Chinese power company.
Investors from America, China and the Middle East are the latest reported to be interested in a bid to build a new nuclear power station on Anglesey. Nuclear energy expert Malcolm Grimston is positive about the news.
Five companies are reported to be interested in building a new nuclear power station on Anglesey. Groups said to be interested include American firm Westinghouse, owned by Japan's Toshiba, a Chinese investor, U.S. power company Exelon and Middle Eastern investors.
In April the German companies behind the plans to build a new nucleur power station on Anglesey pulled out of the project. E.on said that following a strategic review it would not proceed with plans for the Horizon Nuclear Power project along with RWE npower.
£4 million is being spent on helping nuclear energy workers in North West Wales back into work.
The funding aims to help 1,200 staff at the Wylfa and Trawsfynydd sites prepare for future careers.
Wylfa, on Anglesey, is due to stop generating electricity in 2014. Trawsfynydd has already closed, and is in the process of being decommissione d.
The funding comes from the European Social Fund, the Welsh Government, the Nuclear Decommissioning Authority and local councils. Workers will be given career advice, mentoring, training and job-search help.
Hopes for a new power station at 'Wylfa B' were set back last month when two leading power companies withdrew their plans for the site.