This essay examines the memorialization of two pivotal nuclear catastrophes – the atomic bombing of Hiroshima in 1945 and the Chornobyl nuclear disaster in 1986 – through the lens of testimonial writings and Maurice Blanchot’s concept of “the disaster.” Drawing on Japanese hibakusha testimonies and Chornobyl survivors’ accounts, the essay contrasts political memory, which seeks closure and national integration, with cultural memory, which preserves trauma, ambiguity, and unresolved loss. Testimonial writings, rather than commemorating a concluded past, emerge from within the disaster itself, articulating a reality that defies assimilation into redemptive historical narratives.