KALIMER Metal Reactor

The main objectives of the R D program and a tentative schedule with 5 progressing stages for the development of KALIMER(Korea Advanced Liquid MEtal Reactor) are given and the current LMR experiences are briefly described. 

The construction of a prototype or demonstration type KALIMER(Korea Advanced Liquid MEtal Reactor) is essential to accomplish the goal of the LMR development. For the construction time, the year 2011 is suggested as established in the LMR long-term development plan. 

KALIMER-150 (Republic of Korea) Korean Advanced Liquid MEtal Reactor... 

KOREA ADVANCED LIQUID METAL REACTOR (KALIMER)... 

The LMR design technology development project was approved as a national long-term R D programme in 1992 by the Korea Atomic Energy Commission (KAEC), which decided to develop and construct a liquid metal cooled reactor (LMR). Based upon the KAEC decision, the Korea Atomic Energy Research Institute (KAERI) has been developing KALIMER (Korea Advanced Liquid Metal Reactor) [XX-1, XX-2]. 

The break of a pipe reduces the core flow, which results in power-to-flow mismatch for some seconds after the pipe break occurred. However, the power is stabilized, even though the automatic reactor scram is not activated. The GEM play an important role in providing the dominant reactivity feedback in case of an important core flow reduction resulting in the decrease of the GEM level below the top of the active core. The results of the primary coolant pipe break event analyses performed for the Korea Advanced Liquid Metal Reactor (KALIMER), which adopts several advanced design features, prove both a coolant subcooling margin of more than 400 K, and a stable system response. 

The inherent safety characteristic against postulated events is the most remarkable superiority of a liquid metal cooled reactor (LMR) to other type of reactors. One of the major threats to the safety of LMR is a loss of flow event accompanied a failure of reactor shutdown systems. This situation is usually referred to as an unprotected loss of flow (ULOF). The inherent safety of the Korean Advanced Liquid Metal Reactor (KALIMER) during the ULOF [I] has been assessed for the situation of all pump trips followed by coastdown. It was assumed that the decay heat is removed by four intermediate heat exchangers (IHXs) and the safety grade system of passive safety decay heat removal system (PSDRS). The results showed that the power was stabilized by the reactivity feedback of the system even though the effect of the gas expansion module (GEM) was not taken into account. 

The present study confirmes the superior resistance and inherent safety of KALIMER against a pipe break accident. The slow response of the hot pool temperature, which is another advantage of pool type liquid metal reactor, is also demonstrated. The GEM is found to be very helpful to provide sufficient negative reactivity for the passive shutdown mechanism and to mitigate the consequences of some spectrum of pipe breaks. 

KALIMER Korean Advanced Liquid Metal Reactor... 

Of the six liquid metal cooled SMRs, three are sodium cooled fast reactors (KALIMER, BMN-170 and MDP), and 3 are lead-bismuth cooled fast reactors (RBEC-M, PEACER-300/550, and Medium Scale Lead-bismuth Cooled Reactor). All designs implement indirect thermodynamic cycles. All sodium cooled SMRs incorporate intermediate heat transport systems (secondary sodium circuits to transport heat to a steam turbine circuit and to prevent the possibility of a contact of water with the primary sodium). All lead-bismuth cooled SMRs have no intermediate heat transport system. All designs use steam turbine power circuit. 

All liquid metal cooled SMRs are designed to operate in a closed nuclear fuel cycle providing for the use of non-aqueous reprocessing methods. The designs of KALIMER, MDP and PEACER make use of the ternary U-Pu-Zr or U-TRU-Zr fuel and pyro-metallurgical reprocessing. The RBEC-M and the Medium Scale Lead-bismuth Cooled Reactor are nitride fuel reactors. The BMN-170 offers flexibility in the selection of fuel with either oxide, or nitride, or metallic fuel being applicable. 

High conversion or breeding are generally inherent to all reactors with the fast neutron spectrum however, they could be improved by the use of dense metallic (KALIMER, BMN-170, MDP, PEACER) or nitride (RBEC-M, BMN-170, Medium Scale Lead-bismuth Cooled Reactor) fuel for the nitride fuel, an option of nitrogen enrichment by is being considered (RBEC-M, Medium Scale Lead-bismuth Cooled Reactor). 

The nuclear design of the KALIMER core is based on the core design criteria discussed below and on the constraints given in Table XX-2, derived from the currently available metal fuel database. Altogether, they define the important performance parameters of the reactor that assure proper performance and safety of fuel and core. 

The present study analyzes a postulated break in the primary pump discharge pipe to assure the inherent safety of KALIMER. KALIMER is a pool-type liquid metal sodium cooled fast reactor plant. The main concern of the accident is the amount of subcooling margin reduction, i.e., the degree of increase in the fuel and the coolant temperatures. The stabilization of power associated with reactivity feedback is also an important aspect of the accident. The analysis is performed with the SSC-K code, which was developed on the basis of the SSC-L code for the... 

KALIMER is a pool-type liquid metal-cooled reactor that has four intermediate heat exchangers (IHXs), four electromagnetic-type primary coolant pumps. In the KALIMER conceptual design [3], focus has been on the nuclear steam supply system (NSSS) and essential BOP (Balance of Plant) systems. The ultimate objectives for the KALIMER conceptual design are to make it safer, more economical, more resistant to nuclear proliferation, and yield less impact on the environment. Figure 1 represents the sehematie of the KALIMER NSSS. 

---