精确的衰变热计算在反应堆设计和安全运行中起着至关重要的作用。裂变产物的β强度分布是衰变热计算中的关键数据，但长期以来受到“pandemonium效应”的干扰，实验给出的β强度分布有系统性的偏差，导致衰变热的求和计算无法和积分实验完全符合。伽玛全能量测量方法(TAGS)被认为是解决这一问题的有效途径，为此经合组织核能署(OECD-NEA)和国际原子能机构(IAEA)建议了一系列亟需进行TAGS测量的关键核素。. 北京放射性离子束装置(BRIF)的建成为在国内开展裂变产物β衰变测量提供了绝佳机遇。本项目计划：1、研制一台超高效率的TAGS装置，首次在国际上消除TAGS谱分析中的理论依赖性，给出更精确可靠的β强度分布。2、在BRIF上通过质子诱发238U裂变产生136I等关键裂变产物核束，并利用TAGS对其β强度分布进行精确测量，为反应堆衰变热计算提供可靠数据。

An accurate estimate of the decay heat is crucial for the design and safe operation of the reactor. The β decay intensity distributions of fission products are the key data in the calculation of decay heat. However, the pandemonium effect leads to systematic uncertainties of the β intensity distributions, which are believed to account for the discrepancies between summation calculations and integral measuremnts of decay heat. Total absorption gamma-ray spectroscopy (TAGS) provides an effective solution to the pandemonium effect. Therefore the Nuclear Energy Agency within Organisation for Economic Co-operation and Development (OECD/NEA) and International Atomic Energy Agency (IAEA) suggested a series of fission products which are needed to be refined by TAGS measurements...The Beijing Radioactive Ion-beam Facility (BRIF) provides a great opportunity to perform measurements of β decay of fission products in China. We plan to develop a TAGS with super high detection efficiency, which will remove the dependency on nuclear theory in the analysis of γ spectrum. This device will be used to measure β intensity distributions of several key fission products, such as 136I et al., which will be produced by proton induced fission on 238U at BRIF.