(first grid connection on 2018-06-30) in China. In the United States, reactor designs are certified by the Nuclear Regulatory Commission (NRC). , the commission has approved seven new designs, and is considering one design more as well as renewal of an expired certification. Response and criticism Proponents of nuclear power and some who have historically been critical have acknowledged that third generation reactors as a whole are safer than older reactors. Edwin Lyman, a senior staff scientist at the Union of Concerned Scientists, has challenged specific cost-saving design choices made for two Generation III reactors, both the AP1000 and ESBWR. Lyman, John Ma (a senior structural engineer at the NRC), and Arnold Gundersen (an anti-nuclear consultant) are concerned about what they perceive as weaknesses in the steel containment vessel and the concrete shield building around the AP1000 in that its containment vessel does not have sufficient safety margins in the event of a direct airplane strike. Other engineers do not agree with these concerns, and claim the containment building is more than sufficient in safety margins and factors of safety. The Union of Concerned Scientists in 2008 referred to the EPR as the only new reactor design under consideration in the United States that "...appears to have the potential to be significantly safer and more secure against attack than today's reactors." There have also been issues in fabricating the precision parts necessary to maintain safe operation of these reactors, with cost overruns, broken parts, and extremely fine steel tolerances causing issues with new reactors under construction in France at the Flamanville Nuclear Power Plant. Lists of Generation III reactors Generation III reactors currently operational or under construction Generation III designs not adopted or built yet Lists of Generation III+ reactors Generation III+ reactors currently operational or under construction Generation III+ designs not adopted or built yet See also Generation II reactor Generation IV reactor List of reactor types References External links Nuclear Reactors Knowledge Base, IAEA Advanced Nuclear Power Reactors , World Nuclear Association, May 2008 Nuclear power reactor types