**4.2.3 Axial temperature profile in the hot channel**

16 Nuclear Reactors

Fig. 14. Outlet coolant temperature as function of the thermal power

**4.2.2 Radial temperature profile along the core coolant channels** 

figure (Veloso, 2005).

Figure 15 shows the radial core coolant temperature profiles (inlet/outlet channel temperatures) at 265 kW. Theoretical results using the PANTERA code are also shown in the

Fig. 15. Radial temperature profile in the core coolant channels at 265 kW thermal power

The experimental bulk coolant temperatures profile in Channel 1 is shown in Fig. 16 as a function of the axial position, for the powers of 265 kW and 106 kW. Figure 16 shows also the curve predicted from the theoretical model using the PANTERA code at 265 kW (Veloso, 2005). The figure shows also the experimental results for other TRIGA reactors Bärs & Vaurio, 1966; Haag, 1971) and (Büke & Yavuz, 2000).

The experimental temperature profile along the coolant is different from that predicted from the theoretical model. Ideally, the coolant temperature would increase along the entire length of the channel, because heat is being added to the water by all fuel regions in the channel. Experimentally, the water temperature reaches a maximum near the middle length and then decreases along the remaining channel. The shape of the experimental curves is similar to the axial power distribution within the fuel rod as shown in Fig. 9. Although Channel 1 is located beside the control rod, the axial temperature profile was not influenced by a possible deformation of the neutron flux caused by this rod, because it was in its upper position, i.e. outside the core. The actual coolant flow is quite different probably, because of the inflow of water from the core sides (colder than its centre).

Fig. 16. Axial bulk coolant temperature profile along the Channel 1
