Reactor core inspection of nuclear reactors is an essential function of operating a nuclear power station that must achieve the highest quality to ensure continued power supply with the best plant safety and efficiency. A key part of the maintenance program is the inspection of the nuclear reactor cores. To perform this operation, a specialist machine with TV inspection and bore measuring isused. The machine is lowered to engage with the reactor standpipes by an electriclinear actuator.
The machine is called the NICIE (New In-CoreInspection Equipment). It was developed by BNS Nuclear Services, a British engineering and site services contractor for the nuclear market sector, who worked in close partnership with Power Jacks to design and manufacture the main linear actuation unit engaging the machine with the reactor standpipe. Four additional jacks act as stabilisers when the machine is coupled to the standpipe.
The NICIE inspects nuclear reactors by lowering a camera down into the reactor fuelchannel to provide measurement and maintenance checks. The main body of the machine is raised and lowered to engage it withthe reactor stand pipes. A specially designed electric linear actuator performs this actuation.
The actuator is designed to lift and lower the 20kN load over a stroke of 525mm with the end of travel signalled by proximity sensors installed in the actuator. To maintain a rigid column over the stroke, the actuator has two internal guidance mechanisms for the ram. As a safety feature the ram is fitted with a proprietary clutch to act, as a mechanical fail safe, to prevent an overload condition should external control systems fail. Powering the actuator is a 0.75kW motor with integral brake for position holding and an auxiliary hand drive shaft should manual operation be required. The machine itself is mounted on wheels for easy transportation, however when positioned for use, four screw jacks at the base of the machine takethe weight off the wheels similar to stabiliser jacks on mobile cranes.
Hinckley Point Power Station, a nuclear power station near Bridgwater, Somerset, on the Bristol Channel coast of south west England, will be operating the hoist, that is currently being tested by BNS Nuclear Services at Whetstone in England. It is an Advanced Gas-cooled Reactor (AGR), which was designed to generate 1250MW of electricity.
Alex MacMillan, leading design engineer, of BNS Nuclear Services, now operating under the Babcock Group., said that the products from Power Jacks for the NICIE hoist were delivered on time and on budget and are now fitted to the first of two machines.
Frank Shinn, Power Jacks area sales manager for the East Midlands says: ”This is a typical application from BNS Nuclear Services - two of our products on one machine, one of which has been engineered specifically to suit, the other is a standard unit. As usual the selection process was an enjoyable and interesting experience, dealing with engineerswho are specialists in the business”.