ROF Pembrey A World War I explosive factory , which was to be later known as NEF Pembrey was built , by Nobel ' s Explosives , with British Government approval , near the village of Pembrey , Carmarthenshire , Wales . The factory was built on a site consisting of mainly sandhills and sand dune s to provide some protection against damage caused by an explosion . Its main product was TNT ( Trinitrotoluene ) used for shell filling . The same site was used in World War II to build another explosive factory ROF Pembrey , which also made TNT . Like all explosives factories , they needed a guaranteed year - round supply of water and good transport links . The site was connected to the Great Western Railway at Pembrey . Nineteenth century dynamite factory . A dynamite factory appears to have been built on a site at Pembrey in 1882 by the New Explosive Company of Stowmarket ; it was bought by their competitors , Nobel ' s Explosives Company , in 1886 / 1887 and production was partially run - down . Ownership was then transferred to the South Wales Explosive Company , a subsidiary of Nobel ' s . World War I : NEF Pembrey . The site was then used by Nobel ' s Explosives to build a TNT / propellant factory in 1914 with Government approval . Its construction was a response to the need to drastically increase the production of shells in World War I ( see Shell Crisis of 1915 ) . The Pembrey site was one of the first purpose - built TNT manufacturing sites , in the United Kingdom , in World War I . The factory was initially owned by Nobel ' s Explosives , but in 1917 it was taken over by the Ministry of Munitions and it became a National Explosives Factory ( NEF Pembrey ) . It produced 15 , 000 tons of TNT and 20 , 000 tons of propellant . The site was described as some . After the end of World War I , it closed and the administration building became a convalescence home for children from the families of unemployed miners . Its water supply works were taken over by the nearby town of Llanelli and used to supply the town with water . World War II : ROF Pembrey . Work started in July 1938 to build a new factory on the site , with the Ministry of Works acting as Agents . It opened in December 1939 under the control of the Ministry of Supply as one of several explosive Royal Ordnance Factories making TNT . Unlike the other TNT ROF ' s , however , ROF Pembrey also made tetryl and ammonium nitrate . Some 3 , 000 people were employed there in World War II . After the end of World War II , it continued to manufacture TNT and tetryl for military use ; and ammonium nitrate for agricultural use as a fertiliser . From 1944 onwards , ROF Pembrey undertook breakdown of surplus ammunition , such as 4 . 5 inch anti - aircraft shells and bombs . The TNT being steamed out and then burnt . The chemical properties of explosive products manufactured or otherwise handled here , including TNT and ammonium nitrate , were continually sampled and tested in the chemical laboratory by technicians known as Junior Analysts . They included young women who were exposed to these hazardous materials on a daily basis . The title of Junior Analyst is still ( 2009 ) cited as a qualification for employment advertised in the region . Closure and disposal . ROF Pembrey closed towards the end of 1964 . In July 1965 the majority of the site , of leasehold land , was returned to the Forestry Commission and now forms Pembrey Country Park ; and of freehold land was sold to a construction company .