=New equipment Validation programme for pre-service inspectors

The Inspection Validation Centre (IVC) of AEA Reactor Services has begun an 18 month programme to validate the procedures and personnel of OIS, the inspection agents chosen by Nuclear Electric,to carry out the pre-service ultrasonic inspection of Sizewell B Incredibility of Failure (IOF) plant.

The contract uses the facilities established at the IVC under the terms of an earlier contract to validate procedures, equipment and personnel for the ultrasonic inspection of the Sizewell B reactor pressure vessel and the manufacturing inspections of the IOF plant.

The new work involves several Sizewell B primary circuit components - the steam generators, pressurizer and primary pumps - and will consider the inspections to be applied to the circumferential and nozzle-to-shell welds, nozzle inner radii and the pump flywheel forging.

The validation will provide independent confirmation that OIS personnel are capable of using manual and automated methods to find and size any flaws of structural concern in these components.

IVC will exercise a three-phase control throughout, beginning with theoretical and practical reviews of the procedures devised by OIS. OIS will then carry out a practical inspection, split into detection and sizing stages, after which IVC will issue a report on performance to Nuclear Electric.

IVC is designing and fabricating 13 test specimens of representative geometries containing flaws of known character and precise size, within Nuclear Electric's specification. The flaw populations in the test

Simulated reactor coolant pump flywheel under Service's Inspection Validation Centre

specimens are kept secure by IVC to ensure that the practical test is completely independent. Fabrication of the test specimens has used the welding techniques developed under the reactor pressure vessel contract.

The first test specimen is a simulated reactor coolant pump flywheel, a component which is attached to the pump shaft by three keyways. The inspection work on the flywheel involves the insertion of sophisticated ultrasonic transducers into six inspection holes equally spaced around the flywheel. This is in order to access the bore and keyways where in-service flaws could originate. Inspection data is recorded for subsequent analysis.

The other test specimens will simulate steam generator and pressurizer circumferential welds, as well as weldments typical of those that will join main and auxiliary feedwater nozzles to these vessels.

The nozzle inner radii will present an inspection challenge owing to the geometrical configuration of these components. This stage of the programme will involve

ultrasonic testing at AEA's Reactor

considerable mathematical processing of the test results by the IVC to assess performance.

IVC, AEA Reactor Services, Risley, Warrington, Cheshire WA3 6A T, UK

Acoustic emission system checks transport containers

An acoustic emission (AE) testing system, designed for structural integrity tests of railway tank wagons has been developed by Physical Acoustics Corporation. Emphasis is placed on the integrity of stub or non-continuous draft sills, or sill-to-tank attachment welds.

The new system, developed in collaboration with Monsanto, is based on applying loads to the wagon using a twist bar. The instrument incorporates 24 channels in a high density configuration, a built in colour CRT and menu driven software. AE activity is displayed in real time by colour-coded symbols within a graphical or pictorial representation of the structure.

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New e timescales, and hard-copy colour-graphic images were provided which were used as the basis for re-licensing the vessels.

See-Scan is a defect imaging system designed for manual ultrasonic scanning of complex structures. A solid-state TV camera monitors the position of an LED mounted on the ultrasonic probe during the inspection. The system converts the inspection data into an immediate graphics display, in C-scan format, colour-quantized to show the position and depth of corrosion or internal flaws.

Sonomatic Ltd, 20 Rivington Court, Hardwick Grange, Woolston, Warrington WA 1 4RT, UK

Testing railway wagon sills with the specially designed AE system from Physical Acoustics Corporation

Defects can be located on the wagon and the wagon's underlying structural supports as well.

The AE technique has several significant advantages over other inspection procedures. These include:

• The test is performed without removing any insulating jackets, trucks, couplers or draft gears.

• The test does not require stripping of paint from welded surfaces.

• It wil l detect sub-surface as well as surface defects.

• A complete stub sill inspection can be performed in 2 h.

• It does not require 'shopping' of wagons to perform the test. It can be performed at plant or field locations.

• It is highly sensitive to finding small active flaws.

Physical Acoustics, PO Box 3135, Princeton, NJ 08543, USA

Corrosion survey on shell t ransport vessels

Transport vessels for chemicals produced at Shell's Stanlow refinery have been inspected ultrasonically by Sonomatic. Safety regulations require that vessels of this type are shown to be fit for purpose when their licence expires 12 years after they are built. The See-Scan ultrasonic flaw detection and imaging system was used to inspect the belly, parts of the dished ends and parts of the sides of three vessels used to convey industrial chemicals.

The alternative to See-Scan inspection was to open the vessels, clean them and inspect visually from the inside. The time required for cleaning is three weeks; See-Scan inspection took two days. The inspections were performed within the prescribed

Personnel qual i f icat ion services

TWI has expanded its range of NDT personnel qualification services by broadening its support for employers setting up ASNT (American Society for Non- Destructive Testing ) schemes. Employers using the ASNT system for qualification of their NDT staff can call on TWl to help with schemes covering liquid penetrant and electromagnetic testing. This is an extension of the Institute's existing service covering schemes for ultrasonic and magnetic particle testing.

Under the ASNT system, an employer sets out a policy regarding training, experience and examination requirements for his certified NDT personnel, and is responsible for carrying it out. Many companies use an outside agency to set up and run their schemes. TWI's experts, Bob Rollason (l iquid penetrant testing) and Dave Davies (electromagnetic testing), hav~ been qualified under the ASNT Level III scheme and can provide outside agency services.

TWl Qualification Services, Abington Hall, Abington, Cambridge CB 1 6AL, UK

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