Salt, molten, cooling

Furthermore, HEEP will consider several reactor concepts including water reactors such as PWR and PHWR for the lower temperature range, the very high temperature reactors (VHTR), fast breeder reactors (FBR) and molten-salt cooled reactors for the high temperature range, and super-critical water reactor (SCWR) capable of output temperatures up to around 625°C for the medium range of temperature. 

Molten salt-cooled reactor (MSR), with a fluid fuel and an indirect power cycle. 

The R D Requirements for the Molten-Salt-Cooled AHTR and Helium-Cooled VHTR Have Much In Common... 

Higher output temperatures. The maximum exit eoolant temperature for a molten-salt-cooled reactor can be higher than that for a gas-cooled reactor— assuming the same maximum fuel... 

Heat conduction to earth. Heat is conducted to the earth surroimding the silo and ultimately to the environment. The 600-MW(t) MHTR uses the same approach for ultimate heat rejection in a beyond-design-basis accident. However, significant differences are noted between gas-cooled and molten-salt-cooled reactors in their ability to reject heat to the ground. 

H. Zhao and Per F. Peterson, A Reference 2400 MW(t) Power Conversion System Point Design for Molten Salt Cooled Fission and Fusion Energy Systems, University of Califomia-Berkeley, Department of Nuclear Engineering Report UCB TH-03-002 (Nov. 20, 2003). 

C. W. Forsberg, P. Pickard, and P. F. Peterson, Molten-Salt-Cooled Advanced High-Temperature Reactor for Production of Hydrogen and Electricity, M/c/ear Technology, 144, 289-302 (2003). 

Graphite itself also has the ability to bind and contain tritium, and some modern efforts seek to employ that behavior through increased surface area such as the case with pebble bed, molten salt-cooled designs (Peterson et al., 2008). Graphite also has been seen to increase its tritium retention with neutron irradiation, which aids in this area (Causey, 1989). 

Another solution is to simply avoid the use of either lithium-7 or beryllium in the carrier salts. This is not considered an option for most breeder MSR designs due to increased neutron absorptions in the potential substitutes such as NaP, RbP, KP, and/or Zrp4- Furthermore, for the new field of molten salt cooled, solid-fueled work (see Section 7.1.5.1.2), FLiBe is needed to assure a negative void coefficient. Burner MSR versions are the notable exception and allow increased carrier salt options, as neutron losses are far less of a concern. 

About thirty concepts of small reactors without on-site refuelling are being analyzed or developed in the Russian Federation, Japan, India, the U.S.A., Brazil, and Indonesia. They cover different reactor lines water cooled, sodium cooled, lead or lead bismuth cooled and molten salt cooled reactors. 

Annexes I-XXX present the contributions from Member States — structured design descriptions of water cooled, gas cooled, liquid metal cooled, and non-conventional (molten salt cooled, etc.) small reactors without on-site refuelling. 

High temperature lead cooled, molten salt cooled and gas cooled reactor concepts for hydrogen production and other applications. 

TABLE 6. HIGH TEMPERATURE GAS COOLED, LEAD COOLED, AND MOLTEN SALT COOLED REACTORS... 

Table 3 lists technical specifications for small autonomous reactors Table 4 contains specifications for water cooled reactors Table 5 gives data for liquid metal cooled reactors and Table 6 presents the characteristics for high temperature lead, gas, or molten salt cooled reactors. 

High temperature designs including hydrogen production 15-25 years Pb and molten salt cooled reactors at 700°C to 1000°C core outlet temperature using nitride or TRISO type fuel... 

RRC KI develops a concept of a high temperature autonomous micro-particle fuelled molten salt cooled reactor — the MARS. It is currently designed with a capacity of 16 MW(th) and a 15 to 60-year refuelling interval (ANNEX XXVm). The concept incorporates a fixed bed of HTGR type spherical fuel elements with TRISO fuel and a molten salt coolant. The secondary circuit makes use of an open air-turbine cycle. 

MICRO-PARTICLE FUEL AUTONOMOUS MOLTEN SALT COOLED REACTOR (MARS)... 

MARS is the Russian abbreviation for a micro-particle fuel autonomous molten salt cooled... 

No operations with fuel are performed during the entire reactor lifetime therefore, there is no storage capacity for fresh or spent fuel elements on the site. Different from pebble bed high temperature gas cooled reactors (HTGRs) and previous high temperature molten salt cooled reactors with HTGR type fuel (abbreviated as VTRS in Russian), the MARS concept incorporates no pebble transport. 

XXVIII-7] FORSBERG, C.W., et al.. Molten-salt-cooled advanced high-temperature reactor for production of hydrogen and electricity. Nuclear Technology, 144, pp. 289-302 (2003). 

For some applications, such as thermochemical production of hydrogen, much of the heat must be delivered above a specific temperature to drive chemical reactions. For any required temperature of delivered heat, molten salt cooling allows for lower reactor-core exit cooling temperatures than in a gas-cooled reactor. 

If one compares a helium-cooled and a molten-salt-cooled high-temperature reactor, a helium cooled reactor (the GT-MHR) with a peak temperature of 850 C delivers its average heat at the same temperature as a molten-salt-cooled AHTR with a peak coolant temperature of 750 C. This implies that for any given peak temperature, the AHTR will have substantially higher efficiency that the gas-cooled reactor with the same peak temperatures. Alternatively, for the same efficiency the AHTR can operate at lower peak temperatures. 

About 50 concepts and designs of the innovative SMRs are under development in more than 15 IAEA Member States representing both industrialized and developing countries. SMRs are under development for all principle reactor lines, i.e., water cooled, liquid metal cooled, gas cooled, and molten salt cooled reactors, as well as for some non-conventional combinations... 

Molten salt cooled small reactor with pebble-bed fuel MARS (RRC Kurchatov... 

The presentations also outlined certain enabling technologies that may be common for several different reactor lines. For example, coated particle or pebble bed type fuel is considered for use not only in high temperature gas cooled reactors, such as PBMR and HTR-PM, but also in several innovative water cooled, molten salt cooled, and even lead-bismuth cooled SMRs, such as PFPWR50 (Japan), VKR-MT (Russia), perhaps FBNR (Brazil), MARS (Russia), and CHTR (India). Some projections for the advanced high temperature structural materials of... 

Some technologies may be common between primary and secondary circuits of different SMRs. A remarkable example is the flibe secondary circuit of the STAR-H2 reactor, which is a high temperature molten salt loop that transfers heat from the lead-based primary circuit to the multi-application balance of plant. A molten salt technology for such loop may have common points with the primary coolant technology for a molten salt cooled MARS reactor of Russia. 

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