基于紧凑型D-D中子源的核燃料U-235富集度及均匀性检测技术研究

中国始终把保障核安全作为重要的国家责任，新形势下核能利用系统的研发，对核燃料棒U-235富集度的均匀性提出更高的质量控制要求，严格防控燃料棒中混入不同U-235富集度的异常芯块。本项目拟采用主动热中子诱发U-235裂变的退激γ射线测量技术，开展基于紧凑型D-D中子源的核燃料棒U-235富集度测量及均匀性检测技术研究。通过热中子诱发U-235裂变物理机制研究，建立核燃料U-235富集度与裂变退激γ射线强度响应模型，相对偏差小于0.5%；通过高通量、紧凑型D-D中子源技术研究，提高D-D中子产额，大于1.0E9 n/s。在完成基础问题和关键技术研究的基础上，搭建基于紧凑型D-D中子源的核燃料棒U-235富集度及均匀性在线检测技术系统，使其具备检测出U-235富集度±1%异常芯块的能力，置信度大于98%。该技术将提升我国核燃料U-235富集度检测的自主化技术和装备，保障核能安全、经济、可靠发展。

China has always regarded nuclear security as an important national responsibility. Under the new situation, the development of the nuclear energy system puts forward higher quality control requirements for the uniformity of the U-235 enrichment in the fuel rods, which strictly prevents and controls the mixing of abnormal pellets with different U-235 enrichment in the fuel rods. This work carries out the measurements and uniformity test of U-235 enrichment with thermal neutron induced fission based on a compact D-D neutron source. By studying the physical mechanism of thermal neutron induced U-235 fission, a response model between the U-235 enrichment and delay γ-ray is established, a relative deviation is less than 0.5%. The studying and development of high-intensity and compact d-d neutron source technology, the yield of d-d neutron source is improved up to 1.0E9 n/s. On the basis of the completion of key basic issues and key technology research, this work develops the installation of measurements and uniformity test of U-235 enrichment with thermal neutron induced fission based on a compact D-D neutron source, which has the ability to differentiate ±1% abnormal pellet with U-235 enrichment. Confidence coefficient is greater than 98%. This developed technology will improve China's independent technology and equipment for the measurements and uniformity test of U-235 enrichment, which also promote nuclear energy development with safe, economic and reliable in China.