共查询到18条相似文献,搜索用时 46 毫秒
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基于蒙特卡罗均匀化理论与有限体积方法,建立了适用于瞬发临界事故分析的三维扩散时空动力学模型。将三维扩散时空动力学模型与非稳态传热模型、辐照裂解气泡模型耦合,对计算程序GETAC-S进行了升级,使其具备了对溶液系统任意几何与材料条件下的瞬态分析能力。使用国际上已有的瞬态装置TRACY的实验数据对GETAC-S进行了验证,结果符合良好。使用GETAC-S对日本的JCO临界事故进行了事故进程反演,证明GETAC-S具备了对复杂溶液系统下的临界事故后果进行评价与反演的能力,为核临界事故的预防、评估和屏蔽提供了理论支持。 相似文献
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核临界安全分析是保证乏燃料后处理厂安全性的关键技术,而现有核临界安全事故分析程序中,或在几何适用范围上受限,或由于计算效率低而工程实用性差。因此,亟需研发一套适用范围大、计算精度高的临界安全分析方法,提高对核临界事故的分析精度,为乏燃料后处理厂提供技术保障。为此,本文针对乏燃料溶液系统特性,基于零维超细群截面制作与全问题并群方法、预估-校正准静态中子动力学计算方法和二维轴对称热工-辐解气体模型,开发了相应的计算程序模块,最终形成了一套具备并行功能的三维乏燃料溶液系统临界安全分析程序hydra-TD。进一步利用该程序对法国SILENE实验装置进行了验证,结果显示:第一裂变功率峰、倍增时间、总裂变次数等关键参数的误差较小,证明hydra-TD程序正确模拟了燃料溶液系统临界过程中的多物理过程,具备临界安全分析的能力。 相似文献
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对瞬态临界事故的准确模拟是核燃料溶液系统临界安全评估的关键因素。现有的辐解气体模型经验参数较多,导致功率特性预测存在较大偏差。为提高模拟精度和避免对模型中经验参数取值的依赖,需对辐解气体模型进行改进。基于对溶液中辐解气体行为的分析和简化假设,建立了包含辐解气体浓度、辐解气泡单位体积物质量和气泡数量密度的守恒模型,并将其与点堆中子动力学模型和二维导热模型相耦合,开发了溶液系统二维瞬态分析程序,通过日本TRACY实验进行了验证。结果表明,程序模拟值与实验数据符合较好,程序模型能够准确模拟溶液系统临界事故的功率变化。 相似文献
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失水事故(LOCA)分析中保守分析方法不利于提高核电厂的经济性,为了满足10CFR50附录K的核电厂LOCA评价要求,基于最佳估算程序RELAP5对其模型进行修改以满足对LOCA的评价要求,同时增大设计裕量。由于附录K涉及模型较多,本文主要对LOCA模型修改和验证方法进行研究,改进了RELAP5程序临界流模型,添加保守的Moody两相临界流模型,同时增加过冷临界流Zaloudek模型,并分别采用分离效应实验装置Marviken、Edward喷放管和整体效应装置Bethsy对程序进行了验证,结果表明添加的模型对模拟喷放过程临界流现象具有足够的可靠性。 相似文献
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氟化铀酰溶液临界事故是核燃料循环设施潜在的一种临界事故,需要做好其相应的事故应急评价,为应急响应提供辅助决策支持。临界裂变次数是核临界事故应急评价的重要内容,也是技术难点之一。它反映了核临界事故的大小和规模,直接影响事故应急防护行动决策。裂变次数估算有多种方法,有各自的适用条件。随着事故发生的时间推移,获取的信息越丰富,选择的评价方法也随之优化。因此提出了基于事故进程的氟化铀酰溶液临界裂变次数估算方法,该方法解决了临界事故应急评价实际应用问题及技术人员选择何种评价方法的困难问题。 相似文献
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建立考虑裂纹形态参数影响的周向穿透裂纹临界泄漏率的计算模型,以此为基础编制计算程序PC-Leakflow2。介绍程序的计算流程及求解方法,对影响裂纹临界泄漏率的各个输入参数进行敏感性分析,用文献中的临界泄漏率试验数据对PC-Leakflow2程序的计算结果进行验证。用PC-Leakflow2程序和经典的临界流模型对相同的例题进行计算,计算结果表明:临界泄漏率的大小受裂纹形态参数的影响较强;经典的临界流模型会显著地高估紧密裂纹的临界泄漏率。 相似文献
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【《欧洲核综览》 1999年第 3— 4期报道】 任何一个处理高于某一最小量易裂变材料的工厂都要安装临界事故探测报警系统。在核电厂的反应堆内 ,临界属于一种受控事件 ,在厚屏蔽墙的后面产生。但在易裂变材料精炼、浓缩、加工、使用、贮存、后处理或处置的任何地方 ,临界偶有发生。据报道 ,全世界发生过 5 3起临界事故 ,其中包括前苏联的 12起。临界事故可能产生非常严重的影响 ,因为这种意外事故可能在几乎没有或根本没有屏蔽的地点发生 ,使工厂操作人员摄取大量剂量。 11起事故造成人员死亡。即使后处理厂设有非常厚的屏蔽墙 ,也不足以避… 相似文献
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文章提出最小核临界事故源项的分析模型,并给出了相关计算方法,利用MCNP程序计算了不同易裂变材料以及不同物料状态下,发生最小核临界事故时的总裂变次数和中子伽马吸收剂量比等源项参数。通过与已发表文献和已有相关数据进行对比,结果符合良好。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(12):1088-1097
An observation system has been developed as a new instrumentation of TRACY (Transient Experiment Critical Facility) in order to observe the behavior of uranyl nitrate solution and radiolytic gas voids under criticality accident conditions. The system consists of a radiation-resistive optical fiberscope, a light source and a radiation-resistive video camera. The severe radiation environment in TRACY and safety functions as the primary boundary of TRACY were considered in the design of the system. The system has been successfully utilized in the recent TRACY experiments, and provided clear color motion pictures showing the behavior of the solution and radiolytic gas voids. As a result, it was visually confirmed that there is the difference in the behavior of the solution and radiolytic gas voids depending on the conditions of the reactivity addition. The system provides detailed information on the behavior of the solution and voids, and will contribute to the development of a computational kinetics model. 相似文献
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《Packaging, Transport, Storage and Security of Radioactive Material》2013,24(3-4):265-272
AbstractFor the transport of low enriched materials, criticality safety may be emonstrated by applying pessimistic modelling assumptions that bound any realistic case. Where light water reactor (LWR) fuel is being transported, enrichment levels are usually too high to permit this approach and more realistic data are needed. This requires a method by which the response of LWR fuel under accident impact conditions can be approximated or bounded. In 2000, British Nuclear Fuels and Areva Cogema Logistics jointly commenced the Fuel Integrity Project (FIP) whose objective was to develop such methods. ACL were well advanced with a method for determining the impact response of unirradiated fuel, but required further test data before acceptance by the transport regulators. The joint project team extensively discussed the required inputs to the FIP, from which it was agreed that BNFL would organise new tests on both unirradiated and irradiated fuel samples and ACL would take major responsibility for evaluating the test results. Tests on unirradiated fuel rod samples involved both dynamic and quasistatic loading on fuel samples. Pressurised water reactor (PWR) fuel rods loaded with uranium pellets were dropped vertically from 9 m onto a rigid target and this was repeated on boiling water reactor (BWR) fuel rods; similar tests on empty fuel rods were also conducted. Quasistatic tests were conducted on 530 mm long PWR and BWR fuel specimens under axial loading. Tests on irradiated fuel samples were conducted on high-burn-up fuel rods of both PWR and BWR types. These were believed to be original to the FIP project and involved applying bending loads to simply supported pressurised rod specimens. In one test the fuel rod was heated to nearly 500°C during loading. All specimens were subject to axial impact before testing. Considerable experience of fuel rod testing and new data were gained from this test programme. 相似文献
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蒸汽发生器传热管在横向流流体冲刷下引起的振动和磨损是核电厂安全运行的一个关键问题。为了预测二次侧横向流流体作用下蒸汽发生器传热管的振动幅值和磨损情况,对适用于传热管与支撑结构之间存在微小间隙时的非线性分析方法进行研究。采用有限元方法和模态叠加法计算湍流力和流体弹性力作用下传热管的振动响应和平均磨损功率,并自主开发了蒸汽发生器传热管流致振动非线性分析程序。以某核电厂蒸汽发生器传热管为例,计算传热管在防振条和支撑板处存在间隙的情况下的振动响应和平均磨损功率,并与国外程序GERBOISE的计算结果进行比较。两者的计算结果趋势一致,误差在合理范围内。结果表明,自主开发的非线性分析程序与GERBOISE的计算结果吻合良好,能够准确预测在横向流流体作用下传热管的非线性振动响应,可以用于蒸汽发生器设计分析。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(8):903-907
The Japan Atomic Energy Agency (JAEA), Nuclear Fuel Cycle Engineering Laboratories, operates a spent fuel reprocessing plant and MOX (Plutonium-Uranium Mixed Oxide) fuel fabrication plants. Criticality accident detectors have been installed in these facilities. The detector, the Toshiba RD120, is composed of a plastic scintillator coupled to a photomultiplier tube, and an operational amplifier. The alarm triggering point is set to 1.0–3.6 mGy.h?1 in photon dose rate to detect the minimum accident of concern. However, a plastic scintillator is principally sensitive not only to primary photons but also to neutrons by secondary photons and heavy charged particles produced in the detector itself. The authors calculated energy and angular responses of the RD120 criticality accident detector to photons and neutrons using Monte Carlo computer codes. The response to primary photons was evaluated with the MCNP-4B and EGS4 calculations, and photon and X-ray irradiation experiments. The response to neutrons that produce secondary photons and heavy charged particles from neutron interactions was computed using the MCNP-4B and SCINFUL, respectively. As a result, reliable response functions were obtained. These results will be a great help in reassessing the coverage area and in determining the appropriate triggering dose rate level in criticality accidents. 相似文献