Speakers
Description
The MRP is a highly integrated component, optimised for maximum brightness performance at 5 MW proton beam power. The MRP 1 consists of two cold para hydrogen moderators, the so-called butterfly 2 (BF2), that operates at a temperature of around 17K. In addition, a thermal- and pre-moderator, a Beryllium reflector, steel frames (or outer reflectors) and steel supporting structures, which cooled with light water at around room temperature.
During commissioning without beam, on 25th Nov. 2025 cooling water to the MRP stopped due to external circumstances, while the cryogenic parts were at around 35 K. As a result, the water in the thermal- and pre moderator, which is in close vicinity to the cold moderator and the cryogenic supply and return pipes froze. The freezing of the water finally caused sever damages of the MRP 1 beyond the possibility of repair.
This paper describes the damages observed at the outside of the MRP, showing the relevant parts of the design, the design analysis and discussing scenarios of what might have happened. Furthermore, ongoing work is presented, e.g. calculation of freezing and disassembling of the MRP 1.