浅议福岛核电事故对我国核电发展的影响及借鉴

日本福岛核电事故虽然未对我国的环境造成严重影响,但是该事故的发生对我国后续核电的发展必然产生重大影响。我国庞大、密集的核电发展规划在世界能源发展领域是绝无仅有的,无论是在技术路线、标准制订还是在建造、运行的组织管理上,我国核电建设者和管理者都将面临巨大考验。通过分析和借鉴本次日本福岛核电事故的发生、处理过程,将对我国核电发展在多方面提供重要参考,从而促进我国核电规划及核电事故应急体系的持续完善。     

福岛第一核电厂事故源项估算及方法比较

本文参考日本福岛第一核电厂的部分资料,利用美国核管会发布的《轻水堆核电厂事故源项》（NUREG-1465）以及国际原子能机构发布的《为轻水堆设计估算参考源项所提供的简化方法》（IAEA-TECDOC-1127）两份技术文件中的假设条件,分别计算出事故后由堆芯释放到安全壳内的放射性源项。同时通过对堆芯积存量、抑压水池净化...     

福岛核事故中喷洒水溶性树脂降污初探

日本福岛核事故发生后,东京电力公司通过在事故现场喷洒水溶性合成树脂的办法,在污染区表面形成固结层,抑制和控制放射性粉尘的扩散。本文简要介绍了福岛核事故发生的经过,喷洒水溶性树脂的动机,喷洒范围及实施过程。依据相关报告,对福岛核事故中喷洒水溶性树脂的降污效果进行了分析,并就水溶性树脂的降污机理和应用前景进行了初步探讨。喷洒水溶性树脂对固定放射性粉尘等有一定的降污效果,值得我国借鉴和研究。     

A simple mass and heat balance model for estimating plant conditions during the Fukushima Dai-ichi NPP accident

A simple evaluation method for the analysis of thermal-hydraulic transients in reactor pressure vessel (RPV) and primary containment vessel (PCV) is proposed to support understanding the accident behaviors of the Fukushima Dai-ichi nuclear power plant (NPP). Since most of the measurements of the plants were unavailable especially in the early stage of the accident, and the accessibility to the plants had been limited by radiation, analytical investigation for the plant was required to understand the plant conditions such as the magnitude of the damages. In order to provide easy-to-use technical tools to support the analytical investigation, we developed a simplified analysis code, named “HOTCB”, based on total mass and heat balances in a lamped parameter system. The HOTCB code has capabilities to treat two-phase fluid including water, steam, and non-condensable gas in a wide range of temperatures up to highly superheated conditions, and to consider heat structures, i.e. heat capacities and heat transfer to the fluid. The code was provided to Tokyo Electric Power Company (TEPCO) and was practically used for the analysis on the accident. This paper provides the details of the code and simulations of Unit 1 and Unit 2 reactors of Fukushima Dai-ichi nuclear power plant (NPP) as examples to show the usefulness of the code.     

福岛第一核电站事故后放射性废液的泄漏/排放及辐射影响评估

利用日本东京电力株式会社(TEPCO)和文部科学省(MEXT)等机构截止到2011年5月6日公布的较高放射性水平污水的泄漏资料和较低放射性水平污水的主动排放资料,以及海域的辐射环境监测资料和水产品放射性含量监测资料等,分析了泄漏及排放的放射性污水在近岸海域海水中的分布,并初步评估了所致的海洋生物剂量和公众剂量。     

福岛第一核电站事故对近岸海域鱼类的辐射影响

利用福岛第一核电站事故后不同沿岸和离岸距离处的海水中放射性核素137Cs的监测数据,以鱼类为参考水生生物,通过核素137Cs的累积动力学模式对鱼体内核素的动态浓集进行了评估,给出了福岛第一核电站事故后液态放射性释放所致近岸海域水生动物体内核素水平的变化规律。     

福岛第一核电厂2号机组严重事故进程模拟分析

本文应用MELCOR程序,通过建立全厂详细的模型,对福岛第一核电厂2号机组在地震发生后4天(96h)内的严重事故进程进行了模拟分析并与电厂实测数据进行了比较。基于文中假设的模拟计算得到的趋势与电厂现有实测数据较为一致,分析结果表明:假设TORUS隔间内海水淹没一半时,作为新增的外部热阱与RCIC系统耦合工作,可有效地将堆芯衰变热排出,并延缓了安全壳压力上升。96h内安全壳压力未达到过滤排放系统开启值;RCIC系统在事故发生后近3天失效,此后4.6h操纵员通过开启主蒸汽泄压阀(SRV)对反应堆进行快速卸压,然而堆芯在消防水注入时接近完全裸露,继而发生强烈锆水反应;6h内产氢量达到近800kg。事故后期堆芯通道依然维持可冷却几何形状,最终操纵员通过开启第2组泄压阀对反应堆进行卸压,消防水泵得以有效向反应堆注入冷却水,堆芯重新淹没并冷却。     

Validation of MAAP model enhancement for Fukushima Dai-ichi accident analysis with Phenomena Identification and Ranking Table (PIRT)

The Modular Accident Analysis Program (MAAP) model enhancement items to improve the simulation capability for molten corium behavior in the accidents at the Fukushima Dai-ichi nuclear power plants were validated with the Phenomena Identification and Ranking Table (PIRT). The importance ranks of the identified phenomena were evaluated for each time phase through brainstorming and discussion with the experts in the Atomic Energy Society of Japan and the members of the MAAP model enhancement project. When the current MAAP evaluation models were reviewed with the PIRT, it is found that 95 of the 386 high-ranked phenomena were not considered in MAAP 5.0.1. While 62 of these phenomena will have been addressed in the MAAP enhancement project and 25 others are not suitable to be analyzed by MAAP, 8 important phenomena should be considered in post-MAAP enhancement project with additional experiments or fundamental studies.     

Reactive spark plasma sintering of Cs-exchanged chabazite: characterisation and durability assessment for Fukushima Daiichi NPP clean-up

ABSTRACT

Ion-specific media (ISM) have played an integral role in the clean-up and remediation efforts at the Fukushima Dai-ichi disaster site, through the processing of contaminated wastewaters. The use of these materials generates a secondary nuclear waste stream, presenting its own series of engineering problems arising from stringent handling and long-term storage requirements. A reactive spark plasma sintering (SPS) method was investigated for conditioning of the spent cesium exchanged zeolite, chabazite. A natural form of the zeolite was used as an analogue to the engineered ISM used at the Fukushima NPP site. Simulant wasteforms were sintered using different temperature and pressure parameters followed by analysis of phase assemblage, density, and durability (using the product consistency test (PCT)). The results indicated that zeolite structure had collapsed completely, with the exchanged cesium partitioned primarily into a durable feldspar to assure stability of the sintered material for passively safe storage or geological disposal.     

Analysis for iodine release from unit 3 of Fukushima Dai-ichi nuclear power plant with consideration of water phase iodine chemistry

The accident at unit 3 of the Fukushima Dai-ichi nuclear power plant was analyzed with THALES2 for the progression of severe accident coupled with Kiche for the iodine chemistry in aqueous phase. The analysis indicated that, compared with the analysis without the aqueous phase iodine chemistry, a significantly larger amount of iodine was released from the water pool of the suppression chamber (S/C) with forms of molecular iodine and organic iodine due to the repeated operation of the containment venting system. It was also implied in the sensitivity analysis that the late phase release of the volatile iodine species was largely influenced by the pH of the S/C water and gas–liquid mass transfer coefficient under a gas–liquid two-phase flow condition.     

海阳核电厂竣工环保验收实践经验的探讨

根据相关法规标准要求,针对海阳核电厂AP1000机组设计特点,提出竣工环保验收监测方案,根据竣工环保验收监测结果进行了分析评价,得出验收通过的结论。总结了海阳核电厂竣工环保验收监测与评价的经验,分析了竣工环保验收过程中需要重点关注的问题及验收方法,包括验收依据文件的考虑、三废处理性能验证、流出物排放监测验收、非放废水排...     

核电厂事故后应急环境监测谱仪国产化研制

事故后应急环境监测谱仪是福岛事故后开始在我国核电厂环境监测系统使用的一种新型探测器,但目前国内使用的此类设备基本都为进口设备,综合使用成本高昂,严重制约了核电厂应急监测能力的提高。本工作成功研制出事故后应急环境监测谱仪,经过一系列测试,性能指标已达到国际先进产品水平,且软件系统完全开放,批量生产成本仅约为进口设备采购价格的二分之一。研制的事故后应急环境监测谱仪能够在核电厂正常运行和事故情况下发挥有效监测作用,未来具有在其他核设施推广使用的前景。     

Source term estimation of atmospheric release due to the Fukushima Dai-ichi Nuclear Power Plant accident by atmospheric and oceanic dispersion simulations

The source term of the atmospheric release of ¹³¹I and ¹³⁷Cs due to the Fukushima Dai-ichi Nuclear Power Plant accident estimated by previous studies was validated and refined by coupling atmospheric and oceanic dispersion simulations with observed ¹³⁴Cs in seawater collected from the Pacific Ocean. By assuming the same release rate for ¹³⁴Cs and ¹³⁷Cs, the sea surface concentration of ¹³⁴Cs was calculated using the previously estimated source term and was compared with measurement data. The release rate of ¹³⁷Cs was refined to reduce underestimation of measurements, which resulted in a larger value than that previously estimated. In addition, the release rate of ¹³¹I was refined to follow the radioactivity ratio of ¹³⁷Cs. As a result, the total amounts of ¹³¹I and ¹³⁷Cs discharged into the atmosphere from 5 JST on March 12 to 0 JST on March 20 were estimated to be approximately 2.0 × 10¹⁷ and 1.3 × 10¹⁶ Bq, respectively.     

Study on long-term radiation exposure analysis after the Fukushima Dai-ichi nuclear power plant accident: validation of the EU long-term radiation exposure model (ERMIN)

The Fukushima Dai-ichi nuclear power plant accident led to the dispersion of radioactive material by wind that resulted in soil and air pollution over a wide area. Even now, more than 150,000 people in Fukushima prefecture are still relocated from their homes. In order to estimate how long such relocation might continue, we estimated radiation exposures for the 10 years following the accident that occurred on 12 March 2011, using European model for inhabited areas (ERMIN) developed by a partnership of several European organizations. We validated the estimated results of long-term radiation exposure with the observed data at 1, 2 and 3 years after the nuclear accident. We analyzed the deposition velocity and re-suspension coefficient using the observed data on air concentration, amount of falling dust and soil contamination, and compared them with the published data.     

福岛核事故场外环境修复综述及启示

概述了日本福岛核事故后放射性物质的释放和沉积情况。归纳综述了日本福岛核事故后场外环境修复的方针、环境修复法规、环境修复计划以及环境修复的进展和现状。最后提出了我国今后在核事故发生后对于场外放射性环境修复过程中需要关注和探讨的问题。     

新疆伊犁铀矿冶退役场所辐射环境影响现状调查

以新疆伊犁4个铀矿冶退役场所为研究对象,调查其辐射环境影响,包括退役场所的γ吸收剂量率、土壤表面氡析出率以及土壤及水体中的天然放射性核素含量。结果表明,部分退役场所超标情况严重,亟需进一步治理。     

百万千瓦级核电厂地震风险评价和见解

针对特定百万千瓦级压水堆核电厂开展地震概率风险评价,开发了电厂特定的地震危险性曲线和设备的地震易损度曲线,建立地震概率风险评价模型并完成定量化,给出地震风险结果和见解。结果表明,该特定电厂地震风险水平较低,在0.3g～0.6g地震动水平区间内地震风险贡献最为突出。     

我国核设施退役治理标准化现状及建议

回顾了我国核设施退役治理标准化现状,总结了我国核设施退役治理标准存在的问题,对核设施退役治理标准规划和体系、核设施退役治理管理标准、技术标准以及标准的实施和监督等方面提出了标准化工作的建议。