Nuclear design

Nozomu Fujimoto, Naoki Nojiri, Hiroei Ando, Kiyonobu Yamashita

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


The high-temperature engineering test reactor (HTTR) has been designed for an outlet temperature of 950 °C. That is the highest temperature in the world for a block-type high-temperature gas-cooled reactor (HTGR). The functions of the reactivity control system are determined considering the operational conditions, and the reactivity balance is planned so that the design requirements are fully satisfied. Moreover, the reactivity coefficients are evaluated to confirm the safety characteristics of the reactor. The power distribution in the core was optimized by changing the uranium enrichment to maintain the fuel temperature at less than the limit (1600 °C). Deviation from the optimized distribution due to the burnup of fissile materials was avoided by flattening time-dependent changes in local reactivities. Flattening was achieved by optimizing the specifications of the burnable poisons. The original nuclear design model had to be modified based on the first critical experiments. The Monte Carlo code MVP was also used to predict criticality of the initial core. The predicted excess reactivities are now in good agreement with the experimental results.

Original languageEnglish
Pages (from-to)23-36
Number of pages14
JournalNuclear Engineering and Design
Issue number1-3
Publication statusPublished - Oct 2004
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • General Materials Science
  • Safety, Risk, Reliability and Quality
  • Waste Management and Disposal
  • Mechanical Engineering


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