XYLENE POWER LTD.

FNR TEMPERATURE PROFILE

By Charles Rhodes, P.Eng., Ph.D.

DESIGN OPERATING CONDITIONS:
The FNR temperature profile must remain within the design specifications all the way from no load to full load. The design temperature profile is as follows:

LOCATION	100% LOAD	10% LOAD
FNR Set Point Temperature	475 C	475 C
Core fuel center line max, 2 adjacent blocked cooling channels	560 C	~ 492 C
Core fuel center line max, normal operation	520 C	479.5 C
Fuel assembly sodium discharge	460 C	473.5 C
Fuel assembly sodium inlet	420 C	~ 460 C
Intermediate heat exchange bundle sodium inlet	460 C	473.5 C
Intermediate heat exchange bundle sodium discharge	~340 C	448 C
Intermediate heat exchange bundle NaK inlet	330 C	385.5 C
Intermediate heat exchange bundle NaK discharge	450 C	472.5 C
NaK-salt heat exchanger NaK inlet	450 C	472.5
NaK-salt heat exchanger NaK discharge	330 C	312 C
NaK-salt heat exchanger nitrate salt inlet	320 C	311 C
NaK-salt heat exchanger nitrate salt controlled discharge	440 C	440 C
Steam generator nitrate salt inlet	440 C	440 C
Steam generator nitrate salt discharge	320 C	311 C
Steam generator injected water	310 C	310 C
Steam generator discharge steam	400 C	436 C
Steam saturation temperature	310 C	310 C

 

DESIGN ASSUMPTIONS:
1) Full load (1 GWt) sodium temperature rise as it transits the core zone = 40 degrees C
Note that the Na circulation rate at full load is 3X the NaK circulation rate
2) Full load (1 GWt) temperature drop between fuel rod center line and fuel rod surface = 50 C
3) Full load (1 GWt) temperature drop across the fuel tube wall = 10 C
4) Full load (1 GWt) temperature drop across intermediate heat exchange bundle tube wall = 10 C:
5) Minimum load temperature drop across intermediate heat exchange bundle tube wall = 1 deg C
6) Full load temperature drop across NaK/nitrate salt heat exchange tube wall = 10 deg C;
7) Minimum load temperature drop across NaK/nitrate salt heat exchange tube wall = 1 deg C;
8) Full load (1 GWt) temperature drop across steam generator tube wall below water level = 10 C;
9) Minimum load temperature drop across steam generator tube wall below water level = 1 C;
10) Full load (1 GWt) temperature difference between steam generator upper section salt inlet temperature and steam temperature = 40 C;
11) Steam generator lower section has a recirculation pump and recuperation that raise its water inlet temperature from 100 C to 310 C.
12) Note that there may be maintenance issues related to NaOH and KOH precipitation in the NaK/nitrate salt heat exchanger due to nitrate salt temperatures as low as 311 deg C at minimum load.
 

This web page last updated March 2, 2024