British Energy Case Study - Fuelling Machine Winch Load Monitoring System

TBG have provided British Energy with an experimental Data Logging System that is intended to simultaneously monitor the loads on the three winches in the fuelling machine. The Fuelling Machine is used to carry out refuelling operations and maintenance activities in an Advanced Gas-cooled Reactor (AGR) Power Station. The Neutron Scatter Plug (NSP) is a component part of the fuel plug unit (FPU) that can become stuck after being in a reactor for some time. Vibration can cause a stuck NSP to spontaneously release resulting in possible damage to the FPU. The system is intended to detect that a drop has occurred and store the drop data in a log file. This file can then be retrieved and analysed by site personnel, who in turn will be able to initiate a maintenance schedule should the drop be deemed significant.


System Design

The system was developed using National Instruments Compact FieldPoint consisting of a Real Time controller (cFP-2120), a digital output module (cFP-DO-400), a high-speed analog input module (cFP-AIO-600) and a digital output module (cFP-DI-330). Data from the load sensors attached to the winches is analysed and compared against set ‘Load Band’ parameters. If the readings go above these parameters the system waits a defined period of time for the load to stabilise. Following this wait period the data is once again analysed against a set of steady state parameters and if the load is within these parameters a drop has occurred and the alarm is raised. The load profile for the detected NSP drop is stored to file and the system will continue to monitor the load on all three of the winches. The alarm can be cancelled via an external ‘Cancel’ button within the site facility.


Provision was also given for a suite of test profiles to be sent to the Data Logger system should verification of the system be required. The test system for the data logger is based on MXI-4 technology. Utilising a fibre optic link (PXI-PCI8336) to a PXI chassis (PXI-1031).


A data acquisition card (PXI-6221) is used to send test signals to the data logger via a conditioning box (SCC-2345) containing a voltage to current converter (SCC-CO20). The tester can be connected to any of the three winch channels (via test sockets on the enclosure) to verify its operation. This will allow site personnel to input the required test profile and view the received waveform on the Web interface Screen.


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Design Challenges

The main design challenges developing this system were to implement the system using the LabVIEW Real-Time environment whilst maintaining a data acquisition rate of 500Hz.


Due to the nature of the industry, security restrictions imposed on the system were very strict. Access to the system had to be automated and based on the Windows username. As no other system exists to record the NSP drops, the system had to be designed using theoretical NSP drop profiles.


System Results

Prior to TBG Solutions developing this system British Energy had to assess how much damage an FPU had sustained due to an NSP drop, by carrying out extensive non-destructive testing of the FPU welds. The system allows the size of the drop to be cross-referenced to the damage caused to the FPU. Site personnel will, in time, be able to look at any given drop and decide whether the FPU needs to be taken out of service for maintenance or left in service, thus preventing lost generation with a consequent loss of revenue.


British Energy were able to leave us some feedback for our work with them. Please see their testimonial along with a few others here.