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Description
The European Spallation Source (ESS) is one of the largest science and technology infrastructure project being built in Sweden. Protons at 2 GeV (with a normal current of 62.5 mA) are delivered by a superconducting linear proton accelerator and are injected onto a rotating tungsten target at a pulsed repetition rate of 14 Hz. Neutrons via spallation reaction are moderated to cold and thermal energies by dedicated moderators. Initially, the ESS installed two hydrogen moderators above the target wheel. The cryogenic moderator system (CMS) was designed to circulate subcooled liquid hydrogen at a temperature of 17 K and a pressure of 1.0 MPa to remove the nuclear heating at the moderators, which is estimated to be 6.7 kW for a 5-MW proton beam power. The liquid hydrogen is transferred from the CMS cold box (CBX) to a distribution box (DB) via a main transfer line (HTL) and is split into each moderator transfer line. The CMS is cooled via a plate-fin type heat exchanger by a large-scale 20 K helium refrigeration system, referred to as the Target Moderator Cryoplant (TMCP) with a cooling capacity of 30.3 kW at 15 K. The valve box functions to mitigate transient thermal disturbances caused by the proton beam injections by rapidly adjusting the feed helium flow rate to the CMS within a few seconds. During the CMS cooldown operation, hydrogen gas at 1.9 MPa to the CMS CBX from the hydrogen filling station (FS) located outside the Target building.
The Control Systems implemented at ESS play a pivotal role in synchronizing and ensuring the continuous operation of the various equipment responsible for neutron production for the experimental programs. ESS standardizes on a small set of hardware technologies, or hardware families, for control and monitoring tasks. For control systems operating at low frequencies (<10Hz), industrial automation Programmable Logic Controllers (PLC) by Siemens are utilized. To ensure seamless integration across all control systems, ESS employs the Experimental Physics and Industrial Control System (EPICS) framework. Integration with EPICS is achieved through a custom python-based software tool developed in-house by ESS. This tool generates the necessary code sets to enable integration between a PLC and EPICS Input Output Controller (IOC).
The CMS Basic Process Control System (BPCS) is responsible of controlling a wide array of equipment, consequently the system logic was designed with modularity, ease of expansion, and maintainability in mind. As the first step for the different device types, generic software control blocks with a wide range of features and Operator Interface (OPI) block icons and faceplates were developed. The functionality of these blocks and OPIs developed for the CMS BPCS were also implemented in other BPCSs at ESS.
The process logic is distributed across three distinct PLC CPUs for the CMS CBX, DB and FS, interconnected via an isolated Local Area Network (LAN). Communication between the CMS PLC CPUs is facilitated through open user communication for data exchange over the integrated PROFINET interface of the CPU.
On the other hand, the TMCP control system comprises multiple PLC Central Processing Units (CPU) and Remote Input Output (RIO) modules, and is delivered by Linde Kryotechnik AG, and integrated into EPICS To seamlessly integrate the TMCP and CMS into a unified system, a PROFINET (PN) communication was established utilizing a PN-PN bus coupler. A dedicated control block and Operator Interface (OPI) implemented within the CMS BPCS allow for (enable to) starting and stopping of compressors and turbines, regulation of feed and return temperatures of the TMCP, control the system discharge (high pressure – HP) and suction (low pressure – LP) pressures.
Additionally, utilizing the functions listed above, various Local Protection Functions (Monitoring Function and Failure Actions) were implemented to systematically shut down the CMS for any aberrant occurrences, following a predefined sequence. These functions were verified during the CMS commissioning activities to ensure that they meet the requirements.
| Submitters Country | Sweden |
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