Regarding the front-page Oct. 4 article "Nuke plants come up short in EU stress tests": It is unsurprising that 10 British nuclear power plants do not have hydrogen "recombiners." Recombiners are required for plants that use water as a coolant since hydrogen, the "H" in the H₂O, can be liberated in reaction with Zirconium cladding the fuel rods. All except one of the United Kingdom's reactors are advanced gas-cooled reactors, which use CO₂ as a coolant, so the recombiners are not required.

The remaining U.K. plant, Sizewell B, is a pressurized water reactor. Its original hydrogen safety system diluted any hydrogen releases with air, but it is in the process of being fitted with a hydrogen recombiner, too.

The opinions expressed in this letter to the editor are the writer's own and do not necessarily reflect the policies of The Japan Times.

e. watters