One-loop operation of primary heat transport system in MONJU during heat transport system modifications

Goto, Takehiro; Tsushima, Hiroyuki; Sakurai, Naoto; Jo, Takahisa

Proceedings of 14th International Conference on Nuclear Engineering (ICONE-14) (CD-ROM), 13 Pages, 2006/07

MONJU is a prototype fast breeder reactor. Modification work commenced in March 2005. Since June 2004, MONJU has changed one-loop operation of the primary heat transport system with all of the secondary heat transport systems drained of sodium. Purposes of this change are to shorten the modification period and to reduce the cost incurred for circuit trace heating electrical consumption. Before changing condition, the following issues were investigated to show that this mode of operation was possible. The heat loss from the reactor vessel and the single primary loop must exceed the reactor core decay heat by an acceptable margin but the capacity of the preheater to keep the sodium within the primary vessel at about 200C must be maintained. With regard to heat loss and core decay heat, the estimated heat loss in the primary system was in the range of 90-170kW in one-loop operation, and the calculated reactor decay heat was 21.2kW. Although the heat input of the primary pump was considered, it was clear that circuit heat loss greatly exceeded the core decay heat. As for the preheater, effective capacity was less than the heat loss. Therefore, the temperature of the reactor vessel room was raised to reduce the heat loss. One-loop operation of the primary heat transport system was able to be executed by means of these measures. The cost of electrical consumption in the power plant has been reduced by one-loop operation of the primary heat transport system. The modification period was shortened.

The Prototype fast breeder reactor Monju system startup tests report; Summary report of the system startup tests; Criticality test Power up test(40% power)

Miyakawa, Akira; Hattori, Kazuhiro; Jo, Takahisa

JNC TN2410 2005-002, 278 Pages, 2005/07

JNC-TN2410-2005-002.pdf:30.04MB

In December, 1992, the performance tests (System Startup Tests; SST) of Monju had been started after the integrated function tests. However, coolant leakage in secondary heat transport system occurred at 8th December, 1995. And so, the performance test was interrupted at the stage of the plant output about 40%. Then, it is also in a plant stop state now.In SST, the plant data was measured in all each stage of reactor power from fuel loading to rated power. And, based on the measurement data, the check of the system performance, the evaluation of appropriate design, and the consolidation of the measurement data for future etc. were carried out. There were about 130 test items in SST, 2/3 items of total were indispensable to starting of a plant (these are equivalent to starting test items of LWR), 1/3 items were R&D. Here, summary of past performance test result are organized.

MK-III Performance Tests in JOYO; Transient Response Tests

Kawahara, Hirotaka; Rekimoto, Masafumi; Jo, Takahisa; Ishida, Koichi; Ariyoshi, Masahiko; Isozaki, Kazunori

JNC TN9410 2005-002, 135 Pages, 2005/02

JNC-TN9410-2005-002.pdf:17.48MB

The manual shutdown tests and loss of electric power supply tests were carried out as the transient response test on anomaly condition at 70MWt and 140MWt operation. The decay heat removal tests by main cooling system were carried out after each transient response tests. It was confirmed that the plant protection system operates properly and the reactor can be shut down safely. These results confirmed that the thermal transients are less severe than the design conditions.

Decommissioning status of Prototype Fast Breeder Reactor Monju

Sato, Masami; Jo, Takahisa

no journal, , 

no abstracts in English

Status of MONJU decommissioning Phase 2, 1; Reconsideration of performance maintenance facilities in accordance with the transition to Phase 2 of the MONJU decommissioning plan

Ono, Fumiyasu; Fukushima, Tsubasa; Naruse, Keiji; Matsui, Kazuaki; Obata, Ikuhito; Sawazaki, Hiromasa; Goto, Takehiro; Jo, Takahisa; Uchihashi, Masaya

no journal, , 

By storing fuel assemblies in the fuel pond in Phase 1, MONJU eliminates the residual risk of fuel assemblies remaining in the core, which holds chemically active liquid sodium, and from April 2023, Have moved to Phase 2 of decommissioning. As the decommissioning progresses, plant risks will continue to change. Therefore, we will organize the plant status at each Phase of decommissioning and formulate the concept of performance maintenance facilities for MONJU, which will be necessary in Phase 2, and Performance maintenance facilities were Reconsidered.