2018年1月1日
Burn-up characteristics and criticality effect of impurities in the graphite structure of a commercial-scale prismatic HTGR
Nuclear Engineering and Design
- ,
- ,
- 巻
- 326
- 号
- 開始ページ
- 108
- 終了ページ
- 113
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1016/j.nucengdes.2017.11.003
- 出版者・発行元
- Elsevier Ltd
This study investigates the burn-up characteristics and the criticality effect of impurities in the graphite structure of commercial-scale prismatic High Temperature Gas-cooled Reactor (HTGR), and thereby reconsiders the necessity of high-grade graphite material. In an HTGR, the core is filled with the graphite, and the impurities in the graphite have a non-negligible poison effect on the criticality. To account for the effect of the reflector blocks deployed adjacent to the fuel blocks, GTHTR300, commercial-scale HTGR, employed fine purified grade graphite material IG-110. Ideally, the fuel blocks should also employ IG-110
however, for economic purposes they are constructed from an un-purified grade graphite material IG-11. The poisoning effect of the impurity (which behaves like 10B burn-up and is expressed in boron equivalents) decreases exponentially and eventually saturates at 1% of the initial boron equivalent. However, the reactivity worth of the fuel and reflector blocks with 0.03 ppm boron equivalents (equivalent to 1% of IG-11) is negligible (i.e., <
0.01%Δ k/kk′). Because the poisoning effect of the impurity mimics that of naturally occurring boron, it was evaluated in whole-core burn-up calculations with the impurities represented by naturally occurring boron. According to the results, the criticality of the commercial-scale HTGR is unaffected by the impurity levels (even in the un-purified grade IG-11) because the impurities burn cleanly until the End of Cycle (EOC). Therefore, the economy of electricity generation by HTGRs can be improved by using the un-purified grade IG-11 instead of the fine purified grade graphite IG-110.
however, for economic purposes they are constructed from an un-purified grade graphite material IG-11. The poisoning effect of the impurity (which behaves like 10B burn-up and is expressed in boron equivalents) decreases exponentially and eventually saturates at 1% of the initial boron equivalent. However, the reactivity worth of the fuel and reflector blocks with 0.03 ppm boron equivalents (equivalent to 1% of IG-11) is negligible (i.e., <
0.01%Δ k/kk′). Because the poisoning effect of the impurity mimics that of naturally occurring boron, it was evaluated in whole-core burn-up calculations with the impurities represented by naturally occurring boron. According to the results, the criticality of the commercial-scale HTGR is unaffected by the impurity levels (even in the un-purified grade IG-11) because the impurities burn cleanly until the End of Cycle (EOC). Therefore, the economy of electricity generation by HTGRs can be improved by using the un-purified grade IG-11 instead of the fine purified grade graphite IG-110.
- リンク情報
- ID情報
-
- DOI : 10.1016/j.nucengdes.2017.11.003
- ISSN : 0029-5493
- SCOPUS ID : 85033364015