BACKUP AND ULTIMATE HEAT SINKS IN CANDU REACTORS FOR PROLONGED SBO ACCIDENTS
BACKUP AND ULTIMATE HEAT SINKS IN CANDU REACTORS FOR PROLONGED SBO ACCIDENTS
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DOI：
10.5516/net.03.2013.711
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发表时间：
2013-10
影响因子：
2.7
通讯作者：
T. Nitheanandan;M. Brown
中科院分区：
文献类型：
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作者：
T. Nitheanandan;M. Brown
在加压重水反应堆中，在主冷却剂损失之后，严重的堆芯损坏将随着液体慢化剂的耗尽而开始，从而将顶部排的内部空隙燃料通道暴露于内部和外部的蒸汽冷却条件。暴露在外的燃料通道会升温、变形并分解成堆芯碎片。大量的水被动地降低了事故的进展速度，延长了工程散热器完全丧失的时间。使用MAAP 4-CANDU代码分析了CANDU 6反应堆中可用的备用和最终散热器在缓解长时间电站停电情景后果方面的有效性。分析表明，蒸汽发生器二次侧存水量是事故发生时最有效的热沉。附加的散热器，如主冷却剂，慢化剂，排管拱顶水和端罩水也能够去除衰变热;然而，在假设事件的过程中，产热和排热之间的不匹配逐渐增加。这种不匹配相当于排管容器故障时额外的水存量估计为350 000公斤。在增强型CANDU 6反应堆中，储备水箱中约有2，040，000 kg的水可用于需要散热器的长期紧急情况。
In a pressurized heavy water reactor, following loss of the primary coolant, severe core damage would begin with the depletion of the liquid moderator, exposing the top row of internally-voided fuel channels to steam cooling conditions on the inside and outside. The uncovered fuel channels would heat up, deform and disassemble into core debris. Large inventories of water passively reduce the rate of progression of the accident, prolonging the time for complete loss of engineered heat sinks. The efficacy of available backup and ultimate heat sinks, available in a CANDU 6 reactor, in mitigating the consequences of a prolonged station blackout scenario was analysed using the MAAP4-CANDU code. The analysis indicated that the steam generator secondary side water inventory is the most effective heat sink during the accident. Additional heat sinks such as the primary coolant, moderator, calandria vault water and end shield water are also able to remove decay heat; however, a gradually increasing mismatch between heat generation and heat removal occurs over the course of the postulated event. This mismatch is equivalent to an additional water inventory estimated to be 350,000 kg at the time of calandria vessel failure. In the Enhanced CANDU 6 reactor ~2,040,000 kg of water in the reserve water tank is available for prolonged emergencies requiring heat sinks.