摘要
With respect to a liquid-fueled molten salt reactor(MSR),the temperature coefficient of reactivity mainly includes the moderator temperature coefficient(MTC)and the fuel salt temperature coefficient(FSTC).The FSTC is typically divided into the Doppler coefficient and the density coefficient.In order to compensate for the potentially positive MTC,the FSTC should be sufficiently negative,and this is mostly optimized in terms of the geometry aspect in pioneering studies.However,the properties of fuel salt also directly influence the FSTC.Thus,the effects of different fuel salt compositions including the^(235)U enrichment,heavy metal proportion in salt phase(HM proportion),and the^7Li enrichment on FSTC are investigated from the viewpoint of the essential six-factor formula.The analysis is based on an undermoderated MSR.With respect to the Doppler coefficient,the temperature coefficient of the fast fission factors(a_T(ξ))is positive and those of the resonance escape probability(a_T(p)),thermal reproduction factor(a_T(g)),thermal utilization factor(a_T(f)),and total non-leakage probability(a_T(λ))are negative.With respect to the density coefficient,a_T(p)and a_T(g)are positive,while the others are negative.The results indicate that the effects of the^(235)U enrichment and HM on FSTC are mainly reflected in a_T(e)and a_T(p),which are the dominant factors when the neutron spectrum is relatively hard.Furthermore,the^7Li enrichment influences FSTC by a_T(f)and a_T(λ),which are the key factors in a relative soft spectrum.In order to obtain a more negative FSTC for an under-moderated MSR,the possible positive density coefficient,especially its a_T(p),should be suppressed.Thus,a lower^(235)U enrichment(albeit higher than a certain value,5 wt%in this article)along with a lower HM proportion and/or a higher^7Li enrichment are recommended.The analyses provide an approach to achieve a more suitable fuel salt composition with a sufficiently negative FSTC.
With respect to a liquid-fueled molten salt reactor（MSR）,the temperature coefficient of reactivity mainly includes the moderator temperature coefficient（MTC）and the fuel salt temperature coefficient（FSTC）.The FSTC is typically divided into the Doppler coefficient and the density coefficient.In order to compensate for the potentially positive MTC,the FSTC should be sufficiently negative,and this is mostly optimized in terms of the geometry aspect in pioneering studies.However,the properties of fuel salt also directly influence the FSTC.Thus,the effects of different fuel salt compositions including the-（235）U enrichment,heavy metal proportion in salt phase（HM proportion）,and the-7Li enrichment on FSTC are investigated from the viewpoint of the essential six-factor formula.The analysis is based on an undermoderated MSR.With respect to the Doppler coefficient,the temperature coefficient of the fast fission factors（aT（ξ））is positive and those of the resonance escape probability（aT（p））,thermal reproduction factor（aT（g））,thermal utilization factor（aT（f））,and total non-leakage probability（aT（λ））are negative.With respect to the density coefficient,aT（p）and aT（g）are positive,while the others are negative.The results indicate that the effects of the-（235）U enrichment and HM on FSTC are mainly reflected in aT（e）and aT（p）,which are the dominant factors when the neutron spectrum is relatively hard.Furthermore,the-7Li enrichment influences FSTC by aT（f）and aT（λ）,which are the key factors in a relative soft spectrum.In order to obtain a more negative FSTC for an under-moderated MSR,the possible positive density coefficient,especially its aT（p）,should be suppressed.Thus,a lower-（235）U enrichment（albeit higher than a certain value,5 wt%in this article）along with a lower HM proportion and/or a higher-7Li enrichment are recommended.The analyses provide an approach to achieve a more suitable fuel salt composition with a sufficiently negative FSTC.
基金
supported by the Chinese TMSR Strategic Pioneer Science and Technology Project(No.XDA02010000)
the Frontier Science Key Program of the Chinese Academy of Sciences(No.QYZDY-SSW-JSC016)
关键词
液体燃料
温度系数
反应堆
熔融
盐
节制
MTC
MSR
Molten salt reactor （MSR）
Fuel salttemperature coefficient （FSTC）
Six-factor formula
