Sodium-cooled fast reactor system characteristics

Sodium fast reactor. Sodium-cooled fast reactors are low-pressure, high-temperature reactors. Because these characteristics are similar to the AHTR, the AHTR plant design shares many features with this class of reactors, and specifically the General Electric S-PRISM, for which a considerable R D investment has already been expended. These features inelude overall facility design and decay heat removal systems. 

In an Oak Ridge study [61] various types of fluidized-bed reactors were compared. Systems investigated were (a) a sodium-cooled fast reactor, (b) a gas-cooled system, (c) an organic-moderated reactor, (d) a heavy-water-moderated reactor, and (e) a light-water system. A detailed study of this latter system was carried out to compare its characteristics and performance with solid-fuel heterogeneous pressurized-water reactors. The results indicated that both the light-water-moderated and organicmoderated fluidized reactors showed promise, while the gas-cooled, the D20-cooled, and the fast (unmoderated) reactors were found to be less satisfactory for application of the fluidized-bed technique. 

The moderator expansion characteristic of LWRs is not present in the fast spectrum sodium-cooled reactor yet negative reactivity feedback due to thermal expansion prevails. Doppler feedback is generally the fastest acting feedback mechanism since it is almost instantly affected by core power level. The Doppler feedback inserts negative reactivity into the system as the temperature rises and can thus help limit the extent of power increases. However, as fhe fuel temperature drops with a power reduction, the Doppler feedback adds reactivify which tends to limit the power decrease of the system. 

The Prototype Fast Breeder Reactor (PFBR) is a 1250 MWt, 500 MWe pool-type sodium-cooled reactor under design in India. This closely follows the successful construction and commissioning of the experimental reactor FBTR (40 MWt, 13,2 MWe). A brief design description of the various systems is given below. The main characteristics are given in Table... 

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