Non-contact level sensor assessed by Sellafield

01 November 2010

The Vegapuls radar level transmitter, originally assessed by Exida for SIL applications, is now the first non-contact level sensor to also be independently assessed by Sellafield, as part of the Emphasis project to satisfy the NII. It is now deemed acceptable for this sensor to be deployed in suitable SIL1 applications for the UK Nuclear industry.

Non-contact level sensor assessed by Sellafield

The Control & Instrumentation Nuclear Industry Forum (CINIF) developed the Emphasis program after extensive research. Originally intended as a set of written guidelines, the Emphasis program soon evolved into a software tool that can be used for assessment of SMART instruments suitability for the nuclear industry. Emphasis has been subjected to extensive validation, and has been adopted by the Nuclear Industry Smart Instruments Working Group (NISIWG) comprising of the major players from the UK in this sector. Vegapuls radar level transmitters are SMART instruments and, because of this, the verification of these products to meet Emphasis nuclear requirements is imperative.

Emphasis is based upon a lifecycle approach as specified in IEC61508, and provides an evidence gathering tool in the form of a comprehensive set of questions covering all relevant aspects relating to the company and the product under review

Vegapuls radars are non-contact, and they measure level by being positioned above the surface they measure. The pulse microwave signals they emit reflect back from the product surface to measure distance and compute level/volume. Microwaves are used as they are virtually unaffected by temperature, pressure and vapour in the airspace above a product, and with no moving parts, there is no drift or recalibration required. This means radars are able to be employed in a wide variety of standard and individually tailored level applications. They are capable of measuring ranges up to 35m (75m option) and they can be used for non contact liquid, solid and object monitoring in tanks, vessels, silos, ponds and sumps, in almost any process on site. Working with specialist engineering contractors in the nuclear industry, Vega have also developed a range of individual extended and bent waveguide/antenna assemblies up to several metres long. These are for use where the electronics need to be positioned well away from the point of measurement, with only a metal tubular waveguide and horn antenna mounted in the process area.