Historic buildings experts are to be asked to conduct a study aimed at safeguarding a former top secret munitions factory in Flintshire.
Rhydymwyn Valley Works, near Mold, reputedly made 40,000 mustard gas shells weekly during World War II, and research which helped develop the first atomic bomb was carried out.
Local historians are concerned about the worsening state of the buildings.
They said the studies, ordered by the UK government, were "wonderful news".
The Rhydymwyn Valley History Society (RVHS) wrote to Delyn MP David Hanson asking for help in preserving the Grade II-listed buildings.
In a letter to the MP, Environment Secretary Caroline Spelman said: "Defra is commissioning Purcell Miller Tritton, a historic building consultancy, to undertake a complete condition survey of the buildings on site and create a five year preservation plan.
"This will be developed in conjunction with the conservation bodies for Wales, including Flintshire County Council."
Colin Barber, RVHS chairman, said: "This is wonderful news.
"There's an urgent need to get work started because these buildings wouldn't survive the same level of degradation that they suffered last winter.
"We just need to know now when they're going to get work started."
The RVHS wants the site developed as a visitor attraction.
However, the Environment Secretary ruled out the idea of allowing visitors to tour the tunnels of the underground complex.
Her letter said there was a "potential for toxic gas exposure" and the tunnels offered a risk of trips and falls.
Mr Barber said: "We don't accept what the minister is saying.
"We firmly believe that this site has great potential as a tourist attraction and we'll be seeking a meeting with Defra to discuss the way forward.
"We want to see it opened up that everyone can have the opportunity of visiting the site and finding out what happened there."
A Defra spokesman said there would be a complete condition survey of the buildings and a five year preservation plan would be created.
"This will be developed in conjunction with the conservation bodies for Wales, including Flintshire County Council," said the spokesman.
"Defra remains committed to the long term management of the site as a nature reserve."