Visit to Rhydymwyn Valley Works

Valley Works, in the countryside west of Mold in North Wales, was developed in the late 1930s as a shadow factory for ICI’s Randle Works in Runcorn, where mustard gas was made. The Valley was known by the local residents as a place that made nasty things – there were notices in Welsh and English about what to do in the event of a gas escape! So curiosity was suppressed. In 1941, the MAUD committee reported that an atom bomb was theoretically possible and it was decided to start work on the formidable task of separating uranium isotopes. Again, the site chosen was Rhydymwyn Valley, which had the added advantage of being topographically difficult to bomb accurately.

Perhaps not more than 1Kg of uranium hexafluoride reached Valley Works before the project relocated to Los Alamos in New Mexico. But much basic research on separation technologies was carried out here. ICI’s works in Widnes and Runcorn were involved in developing methods of producing and handling fluorine and hydrogen fluoride in bulk.

The primary objective of the Newcomen visit was to see the tunnels that were created to provide bomb-proof storage for mustard gas munitions. They were used for other purposes as well. There was time to learn about the role of the site in the development of nuclear engineering with a full technical briefing on the Grade II Listed, Building 45, its unique history and role in the Tube Alloys developments. Given the peculiar industrial uses of the site, it was surprisingly attractive and the focus at the Valley is now on nature conservation.

We thank our friends in the Rhydymwyn Valley History Society for allowing us to participate in one of their open days. It is possible that Newcomen North West may arrange a further visit, so putting your name down now might be a sound move!  Should you be interested please contact:

Permission for tunnel tours is reviewed regularly with DEFRA, the site landlord. See also the RVHS to organise an individual tour at:

About the Author: Deborah Jaffé

Deborah graduated with an MA from the Royal College of Art after study at the London College of Furniture and Dartington College of Arts. She is the author of 8 books including: (Queen) Victoria (Carlton 2001); Ingenious Women (Sutton 2003); and The History of Toys (Sutton 2006). She is also co-editor, with Dr Stephen Wilson, of Memories of the Future (Peter Lang 2017).

A long standing interest of her’s is the relationship between industrial design and engineering, which became a focus when researching for Ingenious Women and The History of Toys. It’s also proved to be invaluable in Deborah’s current work as the editor of Newcomen Links.

She was a member of the V&A Trustees’ Committee of the Museum of Childhood; and served on the committee of the Centre for Cultural Memory at the IMLR, University of London. The variety of her work leads to lecturing to a diverse range of audiences on: women and innovation, Frank Hornby and Meccano, design in the Cold War and archives of memory included at:  Newcastle University Business School; the Institute of Patent Agents; the Centre for Cultural Memory; the Wiener Library;  the Newcomen Society and at the British Embassy in Berlin for the launch of Geniale Frauen (the German edition of Ingenious Women).

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