In the 1980s the drop in house coal consumption made a large number of the air braked HEA coal hopper wagons surplus. Some of these were put to use as barrier wagons for the dedicated nuclear flask trains, one coupled between the flask wagon(s), the locomotive and guards' brake van. Wagons allocated to these duties were relettered with TOPS code RNA to make them identifyable from the still active HEA hoppers in coal service. The barrier wagons' hopper doors were often unservicable, sealed or removed, making them unsuitable for coal loading. In some cases the bodywork was later removed and replaced with ballast weights.