On July 6, the China Institute of Atomic Energy (CIAE) announced that the critical heat flux (CHF) test of the annular fuel assembly undertaken by the CIAE has achieved a major technological breakthrough, and successfully obtained the first batch of CHF data for non-uniformly heated full-length rod bundles. It has laid a solid foundation for the evaluation and development of the critical heat flux relationship formula suitable for annular fuel, and supporting the testing of the annular fuel pilot assembly into the reactor. This test uses 5×5 annular fuel to heat the full-length rod bundle non-uniformly, and the axial power distribution of the rod bundle adopts a truncated cosine distribution close to the actual situation in the reactor, which is the first time at home and abroad. (News source: China Institute of Atomic Energy)