Abstract

This study characterizes a failed discharged fuel rod with 53 000 MWd/tonne U from a nuclear power plant in Korea. Chalk River Unidentified Deposits (CRUD) and the oxide layer were observed using an electron probe micro-analyzer (EPMA, SX-50 R, CAMECA, France) with wavelength dispersive (X-ray) spectroscopy. A normally irradiated cladding specimen was analyzed for comparison with the failed fuel rod. The analysis revealed an oxide layer with a thickness of about 10 μm and double-stratified agglomerates of CRUD species shapes. In contrast, sound fuel rods irradiated under conditions similar to failed fuel showed clusters in which Fe, Ni, and Cr were distributed. The main elements constituting the CRUD material, notably Ni and Fe, were located in the same position. Moreover, the thickness of the oxidized layer of the failed fuel rod was found to be significantly different from the thickness of the sound fuel rod.

Consequently, EPMA techniques offer the possibility of identifying and analyzing the CRUD phases and segregations in spent pressurized water reactor fuel. Although phases and segregations are small in terms of the amount expected to be present in background radiation, they nevertheless present a significant analytical challenge.

摘要

这项研究表征了来自韩国核电厂的 53 000 MWd/tonne U 的失效燃料棒。使用具有波长色散 (X 射线) 光谱的电子探针微分析仪 (EPMA, SX-50 R, CAMECA, France) 观察 Chalk River 不明沉积物 (CRUD) 和氧化层。对正常辐照的包壳样品进行分析，以便与失效的燃料棒进行比较。分析揭示了厚度约为 10 μm 的氧化层和 CRUD 物种形状的双分层附聚物。相比之下，在类似于失效燃料的条件下辐照的完好燃料棒显示出团簇，其中分布有 Fe、Ni 和 Cr。构成 CRUD 材料的主要元素，特别是 Ni 和 Fe，位于相同的位置。而且，

因此，EPMA 技术提供了识别和分析废压水反应堆燃料中的 CRUD 相和分离的可能性。尽管相和偏析在背景辐射中的预期数量很少，但它们仍然是一个重大的分析挑战。