Abstract KHNP recently has obtained the approval for the commercialization of the modified 37-element (or 37 M) fuel bundle and now is loading the 37 M fuel bundles in CANDU-6 reactors in KOREA. One of the main issues for approval was the burnup limit. Due to CANDU design and neutronic characteristics, there was no specific burnup restriction of a fuel bundle. The absence of a burnup limit does not mean that a fuel bundle can stay in the CANDU reactor without a time limit. However, the regulator requested traditional design values as well as the burnup limit reflecting the computer code uncertainty. The method for the PWR burnup limit was not applied to the CANDU fuel bundle. Since there was no approved methodology to build the burnup limit with uncertainties, KHNP introduced a Monte-Carlo method coupled with a 95/95 approach to determine the conservative burnup limit from the viewpoint of the centerline temperature, internal pressure, strain measurement deviation. Moreover, to consider the uncertainties of various computing models, a converted power uncertainty was introduced. This paper presents the methodology and puts forward the limits on burnup, evaluated for each of the existing and modified fuel bundles, in consideration of the pressure tube aging condition.

中文翻译：

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使用蒙特卡罗方法确定 CANDU 6 燃料的燃耗极限

摘要 KHNP 最近获得了改进的 37 单元（或 37 M）燃料束商业化的批准，现在正在韩国 CANDU-6 反应堆中装载 37 M 燃料束。批准的主要问题之一是燃耗限制。由于 CANDU 设计和中子特性，燃料束没有特定的燃烧限制。没有燃耗限制并不意味着燃料束可以无时间限制地留在坎杜反应堆中。然而，监管机构要求传统的设计值以及反映计算机代码不确定性的燃耗限制。PWR 燃耗极限的方法不适用于 CANDU 燃料束。由于没有经过批准的方法来建立具有不确定性的燃耗极限，KHNP 引入了蒙特卡罗方法和 95/95 方法相结合，从中心线温度、内部压力、应变测量偏差的角度确定保守的燃耗极限。此外，为了考虑各种计算模型的不确定性，引入了转换功率不确定性。考虑到压力管老化条件，本文介绍了该方法并提出了对每个现有和改进的燃料束进行评估的燃耗限制。