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Journal Articles

Accumulation of gadolinium isotopes in used nuclear fuel

Suyama, Kenya; Kashima, Takao

Proceedings of International Conference on Nuclear Criticality Safety (ICNC 2015) (DVD-ROM), p.273 - 282, 2015/09

In the technical development of the criticality safety control of the fuel debris of Fukushima accident in Japan, there have been a discussion on a possibility of adopting BUC with FP. The Expert Group on Burnup Credit Criticality Safety (EGBUC) under the Working Party on Nuclear Criticality Safety (WPNCS) in OECD/NEA Nuclear Science Committee had carried out an international burnup calculation benchmark "Phase-IIIB" and "Phase-IIIC" for BWR fuel assemblies. In these benchmarks the difference of the calculation results of $^{155}$ Gd among the participants obtained keen interests because it showed rather larger difference among the participants. Authors has been carried out additional analyses on the accumulation of the gadolinium isotopes in the used nuclear fuel during the burnup. Without cooling time, the assembly-averaged amount of $^{155}$ Gd against the burnup value depends on the burnout property of gadolinium in the burnable poison rods. However, after few year cooling time, $^{155}$ Gd increase drastically by the decay of $^{155}$ Eu. In this case, the amount of gadolinium isotopes in the burnable poison rods has less importance. It means that the adopted parameters and data concerning the $^{155}$ Eu generation have much more importance than the burnup treatment of the burnable poison rods for better prediction of $^{155}$ Gd.

Journal Articles

Outline of simulation code fact for analysis of ventilation system on criticality accident

Tsubata, Yasuhiro; Tashiro, Shinsuke; Koike, Tadao; Abe, Hitoshi*; Watanabe, Koji; Uchiyama, Gunzo

Transactions of the American Nuclear Society, 87, p.60 - 61, 2002/11

no abstracts in English

Journal Articles

Report on the 3rd NUCEF International Symposium (NUCEF 2001)

Bamba, Tsunetaka

Genshiryoku Bakkuendo Kenkyu, 8(2), p.205 - 206, 2002/03

http://www.nuce-aesj.org/lib/exe/fetch.php?hash=443da0=http%3A%2F%2Fwww.nuce-aesj.org%2Fpublishing%2Fjournal%2Fvol8%2FJnuce-Vol8-2-p205-206.pdf

no abstracts in English

JAEA Reports

Proceedings of the 5th NUCEF Seminar; February 27, 2001, JAERI, Tokai, Japan

5th NUCEF Seminar Working Group

JAERI-Conf 2001-015, 92 Pages, 2001/12

JAERI-Conf-2001-015.pdf:13.1MB

no abstracts in English

JAEA Reports

Criticality safety evaluation in Tokai reprocessing plant

Shirai, Nobutoshi; ; ; Shirozu, Hidetomo; ; Hayashi, Shinichiro;

JNC-TN8410 2000-006, 116 Pages, 2000/04

JNC-TN8410-2000-006.pdf:2.77MB

Criticality limits for equipments in Tokai Reprocessing Plant which handle fissile material solution and are under shape and dimension control were reevaluated based on the guideline No.10 "Criticality safety of single unit" in the regulatory guide for reprocessing plant safety. This report presents criticality safety evaluation of each equipment as single unit. Criticality safety of multiple units in a cell or a room was also evaluated. The evaluated equipments were ones in dissolution, separation, purification, denitration, Pu product storage, and Pu conversion processes. As a result, it was reconfirmed that the equipments were safe enough from a view point of criticality safety of single unit and multiple units.

JAEA Reports

Examination of safety design guideline; Safety objective and elimination of re-criticality issues

; ; *;

JNC-TN9400 2000-043, 23 Pages, 2000/03

JNC-TN9400-2000-043.pdf:1.1MB

ln the feasibility study on commercialized fast breeder reactor (FBR) cycle systems conducted in JNC, it is required for candidate FBR plants that the level of safety should be enhanced so as to assure: (1)Comparative or superior safety level to that of light water reactors (LWRs), and (2)releaf of the public from anxiety about potential nuclear hazard. Adopting Passive safety characteristics is one of the measures. To attain the above safety objective, we considered implication of the basic safety principles for nuclear power plants that were created by the international nuclear safety advisory group of IAEA. The way to relieve from the anxiety was also taken into account. Then a definite safety objective was set from the standpoint of prevention of core disruptive accident (CDA). Furthermore, as a definite safety goal relating to reactor coresafety, elimination of re-criticality issues under CDA was set by considering characteristics of FBR in comparison with those of LWR. To examine measures for elimination of re-criticality issues, we developed a quick method to estimate possibility of re-criticality under CDA, by drawing a map about criticality characteristics under CDA in various degraded cores. Then hopeful measures were proposed for elimination of re-criticality issues in sodium-cooled FBR with mixed-oxide fuel. Molten fuel discharge behavior of their measures was preliminarily analyzed. We concluded that discharge capability of "a subassembly with an internal duct" was effective, and that "partial removal of axial blanket" was also effective as one of the measures though it has small effect on core performance.

JAEA Reports