The phases accomplished for the Start-Up Program are:

• Hydraulics characterisation, cold state.

• Primary isolated: selfpresurization test, control loops calibration. Degasification of primary side

• Whole system operation. Secondary side in liquid phase. Initial calibration of condensed tank control loops in temperature and flow. Thermal balance.

• Whole system operation. Operating regime at low power with overheated steam and automatic control.

At present the following results has been obtained:

Self pressurization in the operating range of CAREM-25 with natural convection was confirmed.

The Thermalhydraulic Process was controlled during the different power conditions without major problems The production of over-heated steam is compatible with the CAREM operating conditions.

Considering the loop as an experimental machine the following experience has been obtained:

The Data Acquisition and Control System has fulfilled its required performance. However, some problems related with hardware characteristics aroused: temperature were measured with an accuracy lower than required. An interface between the DACS and the sensors was frequently in needs of recalibration. They are already replaced and a safety controller was added to the Supervision System Some improvements were made: New Fuel Assembly spacer (CAREM design) in order to make a durability test of this component; new measurements in the heat exchanger and new improvements in the valves used for control. Some modification in the condenser design were also needed to reach the full power state (300 Kw of electrical heat). In order to reduced the experimental errors several data will be also recorded through a new interfase, with a lower error and frequency of calibration needs. Improvements in the thermal isolation were also done.