**9.2.3. Thermal characteristics of fuel assemblies**

Thermal characteristics of fuel assemblies with hydrogen coolant are presented in table 4. Characteristics of fuel assemblies with helium coolant are slightly different. Hydrogen is cheaper than helium so it is preferable.



Thermal Reactors with High Reproduction of Fission Materials 211

Entropy Sp.

1,626

volume

0,047

0,246

0

50

100

150

**Pressure, atm**

200

250

~0,001 0

7,764 **5,17** 1

Vapor quality

1

№ re-heater T, оС P, gauge

69,6

275,3

275,9

1 Cooler

2 Water from moderator

3 Water from fuel assembly

4

5 The 1-st overheating

6 The 2-nd overheating

7 The 3-rd overheating

**Temperature, С**

atmospheres

0,304

200

Water-steam 0,1527

45

10

Enthalpy Portion

2625,4

69,3 290,1 0,946

10 0,08 131 610,5 1,645

365 1811,5 3,99

366 2423,1 4,95 0,0074

500 3241,2 6,1446 0,0148

500 3440,4 7,0323 0,076

500 3479,1 7,764 0,354

2865,3

2999,9

**Table 5.** Steam and water parameters in cycle with 3 re-heating at Pmax=200 gauge atmospheres and

Tmax= 500 оС. Theoretical efficiency is 41.7 %, with account of losses on turbine 38.8 %

**Figure 14.** Pressure and temperature dependencies from entropy at final steam quality 1.0.

012345678 **Entropy**

Temperature Pressure

of Q


0,2998

0,2042

0,1436

0,1196

**Table 4.** Thermal characteristics of fuel assemblies with gaseous coolant.

Basic features of these assemblies are listed below.


All this features obtained with simple fuel assembly design and its base elements – fuel rods. Used fuel rods are well fine-tuned at practice of large number of reactors. Small hydraulic losses lead to small required power of coolant pumps. It characterizes costs level for reactor creation and losses level during exploitation.
