钠冷快堆蒸汽发生器小泄漏事故中氢迁移行为研究

Study on hydrogen migration behavior in small leakage accident of steam generator of sodium-cooled fast reactor

钠冷快堆采用钠-钠-水/蒸汽三回路传热模式,二回路钠与三回路水/蒸汽通过蒸汽发生器实现热交换。蒸汽发生器中传热管的微小破损都可能导致钠水反应。为了有效扼制小泄漏事故的扩展,需要及时发现泄漏的发生。本文建立了钠冷快堆蒸汽发生器小泄漏钠水反应一维计算模型,采用Fortran语言编写了一维分析程序,用于计算小泄漏钠水反应氢气产生、迁移过程,并与参考文献计算结果进行了对比。最后,针对蒸汽发生器一根传热管破损分析了泄漏率、钠温对氢离子和氢气在二回路钠中迁移行为的影响。可为钠冷快堆二回路小泄漏探测系统的布置提供参考。

[Background]Sodium-cooled fast reactors adopt sodium-sodium-water/steam three-loop heat transfer mode,heat exchange between the sodium in the secondary circuit and the water/steam in the third circuit is achieved by the steam generator.Even tiny crack of the heat-transfer tube in the steam generator may lead to sodium water reaction.[Purpose]This study aims at hydrogen migration behavior in sodium-cooled fast reactor so as to effectively curb the expansion of small leakage accident by detecting the occurrence of sodium-water reaction in time.[Methods]First of all,a one-dimensional calculation model of small leakage sodium-water reaction in the secondary loop of sodium-cooled fast reactor is established.Then a one-dimensional analysis program is written in Fortran language,which can calculate the generation and migration of hydrogen gas in the sodium water reaction of small leakage.Meanwhile,the calculated results are compared with those of a reference.Finally,in the case where a heat transfer tube of the steam generator is broken,the effects of leakage rate and sodium temperature on the migration of hydrogen in the secondary sodium are analyzed.[Results&Conclusions]Analysis results show that the rate of hydrogen concentration change in the secondary circuit can be used to monitor the occurrence of minor leakage accidents,hence provide a reference for the arrangement of the small leakage detection system in the secondary loop of sodium-cooled fast reactor.