Abstract

A method to determine the absolute activity of ¹³⁷Cs in irradiated nuclear fuel is presented. Using a well-known point-like calibration source in combination with measurements of the gamma-ray intensity from the nuclear fuel and Monte Carlo calculations based on the nominal measurement geometry, the activity content can be determined without prior knowledge of the intrinsic detection efficiency of the gamma-ray detector. The presented method is tested using measurements of the ¹³⁷Cs intensity from spent nuclear fuel of the pressurized water type at the central interim storage in Sweden. Using an assumption of homogeneous distribution of ¹³⁷Cs throughout the fuel, we demonstrate a linear relationship between measured activity and the activity calculated by a state-of-the-art simulation code. For future studies, we suggest some factors that potentially can decrease the uncertainty in the correlation between measured and calculated activity.

摘要

介绍了一种确定辐照核燃料中^{137 Cs 绝对活度的方法。}使用众所周知的点状校准源，结合来自核燃料的伽马射线强度测量和基于标称测量几何的蒙特卡洛计算，可以在没有先验知识的情况下确定活度含量伽马射线探测器。所提出的方法通过测量瑞典中央临时储存的加压水型乏核燃料的^{137 Cs 强度进行了测试。}使用均匀分布的假设¹³⁷Cs 在整个燃料中，我们展示了测量的活动与由最先进的模拟代码计算的活动之间的线性关系。对于未来的研究，我们提出了一些可能降低测量活动和计算活动之间相关性不确定性的因素。