Page 128 - Neutrons for Sciences and Society

Neutrons for Science
BORAL
LEAD SHIELDING
H2O
D2O REACTOR CORE
VERTICAL CUT OF THE COLD SOURCE
H2O
CONDENSOR VACUUM PUMP
TUBE HOLDING THE CELL
AG3 WALL LIQUID D2 FEED TUBE
ZIRCALLOY ENCLOSURE
REFLECTOR TANK VAPOR EXHAUST PIPE
MODERATOR CELL IN A5
CANAL H1
D2
700
PART INSIDE THE REFLECTOR
Chamber
Aluminum sphere in A5 with diameter Ø 380 mm, thickness 1.5 mm, inside a zircalloy vacuum vessel
Volume
D2 liquid: ~ 25 litres D2 gas NTP: 50 m3
Pressure
D2 room temperature: 3 bars D2 at low temperature: 1.5 bars
Specific energy
0.8 W/g in D2
1.5 W/g in aluminium
Total nuclear heating
5.8 kW (of which 3.1 in D2)
Heat losses
1.2 kW
Refrigeration power
10 kW at 25 K, requiring 2 helium compressors (400 kW each)
Average thermal neutron flux at the cold source
5.1014 n/cm2/s
Function
Deuterium liquid vaporises in the sphere. The vapour rises into the helium-cooled condenser, where it liquifies and returns to the sphere.
Fig. 5.9: Diagram of the first version of the cold source. When it was necessary to replace it, an improved version (Fig. 7.4) offered increased intensity and added a vertical beam tube.
French firm Air Liquide. The latter was innovative using a turbine mounted on gas bearings. This was finally chosen; the device has proved to be very reliable and still works after 30 years of service. The cold chamber is inserted vertically into the reflector tank from the upper level. It is located 50 cm from the surface of the core (see diagram, Fig. 5.9). The safety issues have been studied;
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