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首页> 外文会议>International meeting on severe accident assessment and management 2012: Lessons learned from fukushima dai-ichi >PROSPECTS FOR IN-CONTAINMENT CESIUM CAPTURE FOR LIGHT WATER REACTORS
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PROSPECTS FOR IN-CONTAINMENT CESIUM CAPTURE FOR LIGHT WATER REACTORS

机译：轻型水反应器内含铯捕集的前景

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Radioactive cesium and radioiodine are the two most important fission products to consider in the event of a large release. We examine options to trap cesium on sorbents located in containment during an accident to (1) reduce potential cesium releases from containment and (2) reduce in-plant radiation levels to enable greater operator plant access during an accident. The half-life for Cs-134 is 2 years, and the half-life for Cs-137 is 30 years. Consequently, radiocesium will exist in the environment for a number of years, and its dose will be delivered over a long period of time. Methods and materials for the passive capture of aqueous Cs released to the reactor containment during severe accidents were evaluated for 2 BWRs and 2 PWRs. Successful substrates for Cs capture are insoluble and may mimic naturally occurring Cs (pollucite) for improved stability over wide ranges of pH, temperature, and water chemistry. Titanate nanotubes were shown to have good selectivity and high Cs capacity above pH 4. Conservatively, 1 to 2 metric tons of the nanotubes were calculated to be sufficient to absorb all Cs released from even the largest LWRs. Copper ferrocyanide on mesoporous silica was compared against Prussian Blue (iron hexacyanoferrate) over a pH range of 0.1 to 7.3 in three different aqueous chemistries. While the Cs capacity of the two materials was similar, they both exhibit a Cs capacity about 10 times less than the titanate nanotubes. The copper ferrocyanide proved to have greater Cs selectivity and improved stability versus Prussian Blue, which tended to degrade over time. A naturally occurring zeolite known as clinoptilolite was analyzed for its Cs capacity and selectivity over a range of pH (from 1 to 11), temperatures (from 25 ℃ to 60 ℃), and competing cation concentrations. Clinoptilolite proved to have a good Cs capacity (similar to that of the titanate nanotubes) and good Cs selectivity. It can also be heat-treated in order to fix the Cs to the clinoptilolite substrate. A potential challenge for the clinoptilolite is that it is slightly soluble, and its Cs capacity decreases with increasing temperature. Additionally, recent findings indicate that Cs capture on oxides of Zr, Mo, Si, and others may also be viable. Solid, insoluble sorbents for Cs are a promising approach to Cs capture, but three of the remaining challenges are determining how to best manufacture and place the sorbents in the containment, how to ensure their chemical compatibility/stability during a severe accident, and to prove their ability to withstand decay heat from the Cs.
机译：放射性铯和放射性碘是大释放时要考虑的两个最重要的裂变产物。我们研究了在事故发生期间将铯捕获在位于安全壳内的吸附剂上的方案，以（1）减少安全壳内潜在的铯释放量；（2）降低工厂内的辐射水平，以便在事故发生时使操作员能够更方便地进入工厂。 Cs-134的半衰期为2年，而Cs-137的半衰期为30年。因此，放射性铯将在环境中存在数年，并且其剂量将在很长一段时间内传递。对严重事故期间被动捕获释放到反应堆安全壳中的水的Cs的方法和材料进行了评估，评估了2个BWR和2个PWR。成功捕获Cs的底物是不溶的，可以模仿天然存在的Cs（聚硅酸盐），以在宽范围的pH，温度和水化学范围内提高稳定性。钛酸盐纳米管显示出良好的选择性，并在pH高于4时具有较高的Cs容量。保守地，计算出1至2吨的纳米管足以吸收从最大LWR释放的所有Cs。在三种不同的水性化学体系中，在0.1至7.3的pH范围内，将介孔二氧化硅上的亚铁氰化铜与普鲁士蓝（六氰合铁酸铁）进行了比较。尽管两种材料的Cs容量相似，但它们的Cs容量都比钛酸酯纳米管小10倍。事实证明，与普鲁士蓝相比，亚铁氰化铜具有更高的Cs选择性和更高的稳定性，而普鲁士蓝则倾向于随时间而降解。分析了一种称为斜发沸石的天然沸石的Cs容量和在pH值（1到11），温度（25℃到60℃）和竞争性阳离子浓度范围内的选择性。斜发沸石被证明具有良好的Cs容量（类似于钛酸酯纳米管的Cs容量）和良好的Cs选择性。还可以对其进行热处理，以将Cs固定在斜发沸石基质上。斜发沸石的潜在挑战是其微溶性，并且其Cs容量随温度升高而降低。另外，最近的发现表明，在Zr，Mo，Si和其他氧化物上捕获Cs也是可行的。对于Cs来说，固态的不溶性吸附剂是一种很有前途的捕获Cs的方法，但是剩下的三个挑战是确定如何最好地制造和将吸附剂放入安全壳中，如何确保在严重事故中的化学相容性/稳定性，以及如何证明它们承受CS衰变热的能力。

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