Page 169 - Thermal Hydraulics Aspects of Liquid Metal Cooled Nuclear Reactors

Operational aspects of experimental liquid metal facilities 141

COMPLOT system curve characterization
6

5

4
Pressure (barg) 3

2

1

0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
3
Flow rate (m /h)
Pump_deltaP_1 Pump_deltaP_2 Theoretical system curve_Cv=236
Theoretical system curve_Cv=50 Poly. (Pump_deltaP_1) Poly. (Pump_deltaP_2)
Fig. 3.4.6 Theoretical and experimental system curves from the COMPLOT facility—
diagnosis of a valve mounting fault.

discovered that when the actuator was 100% open, the valve was in fact only about
50% open resulting in a C v of 50 rather than the expected 236. A characterization such
as this can assist with fault diagnosis and longer-term performance monitoring.
In addition to the baseline performance characterizations and monitoring discussed
above, it is good practice to record all activities in a facility logbook. This is useful, for
example, to review a particular procedure or system status for any particular exper-
iments or maintain a log of running time or maintenance activities.
Other aspects of system performance should be noted as follows:
l Pump heating: the energy lost from friction and hydraulic losses in the pump is converted to
heat energy. Depending on the pump size and efficiency and the heat losses from the loop,
this rate of heating can be nonnegligible and can be a significant heat source. If active tem-
perature control is not installed or well controlled, stable fluid temperature control can be
difficult.
The high temperatures associated with liquid-metal facility operation, usually implies that
l
significant thermal expansion of piping can be expected, which requires flexible piping sup-
ports such as spring hangers and expansion joints. Routine inspection of piping supports is
recommended to ensure that the system continues to be well supported.
Argon is a commonly used inert gas for HLM facilities. Since argon is heavier than air and is
l
considered an asphyxiant, care should be taken when working on or near these facilities.
Oxygen sensors with audible and visual alarms should be installed in confined spaces (par-
ticularly low-elevation confined spaces) to alert personnel of insufficient oxygen levels.