Defect detectability in the disposal canister lid-weld using the 9 MeV linear accelerator

Stefan Sandlin

Research output: Book/ReportReport

Abstract

The spent nuclear fuel will be placed in specially designed canisters, which consists of a cast iron insert with cannels for the fuel bundles and an outer corrosion barrier of copper with a wall thickness of 50 mm. The copper wall should meet the acceptance criteria regarding soundness of the weld. The canister to lid weld is a critical part in this aspect and it has to be inspected by non-destructive methods. The objective of this work was to investigate the defect detectability in the lid-to-canister weld using the high energy Xray system at SKB (Svenska Kärnbränslehantering AB) in Oskarshamn in Sweden. The system is based on a digital X-ray line detector, a 9 MV linear accelerator and a mechanism for rotating the canister. A test object consisting of a 70 degree sector of the electron beam (EB) welded lid-to-canister joint was used in the measurements. The test object has been equipped with several kinds of artificial defects, mainly in the weld asea. The smallest artificial defects are a groove of 0.5 mm cross-section extending 50 mm from the top of the weld to the root, a 1 × 1 × 1 mm3 cubic defect in the root and a flatbottom bore hole of diameter 1 mm and depth of 1 mm also in the root of the weld. These small defects are clarely observed in the X-ray pictures taken during the test program. Further, image quality indicators (IQI) of wire-, duplex wire-, hole- and step-hole types were used to compare the inspection results with European standards. The minimum requirements set by the standards was fulfilled, however, there are no minimum image quality values given for copper, so the corresponding values for steel were used (as recommended by the standard). The X-Rays project a picture of the weld on the line detector through a varying thickness of copper, therefore there is a risk that small defects may be unobserved if they happen to be situated in the shadow of a sharp thickness change of the copper wall. The presented results are, however, very encouraging and with some improvements in the detector-accelerator setup and in the image processing software are even better results than those presented in this work can be achieved.
Original languageEnglish
PublisherPosiva
Number of pages42
Publication statusPublished - 2010
MoE publication typeD4 Published development or research report or study

Publication series

SeriesWorking Report
Number2009-84

Fingerprint

cans
disposal
linear accelerators
defects
copper
detectors
wire
spent fuels
x rays
Sweden
nuclear fuels
inserts
acceptability
grooves
bundles
image processing
casts
inspection
corrosion
accelerators

Cite this

Sandlin, Stefan. / Defect detectability in the disposal canister lid-weld using the 9 MeV linear accelerator. Posiva , 2010. 42 p. (Working Report; No. 2009-84).
@book{9c0518f217044a6e8a2d90e8f98d8e9a,
title = "Defect detectability in the disposal canister lid-weld using the 9 MeV linear accelerator",
abstract = "The spent nuclear fuel will be placed in specially designed canisters, which consists of a cast iron insert with cannels for the fuel bundles and an outer corrosion barrier of copper with a wall thickness of 50 mm. The copper wall should meet the acceptance criteria regarding soundness of the weld. The canister to lid weld is a critical part in this aspect and it has to be inspected by non-destructive methods. The objective of this work was to investigate the defect detectability in the lid-to-canister weld using the high energy Xray system at SKB (Svenska K{\"a}rnbr{\"a}nslehantering AB) in Oskarshamn in Sweden. The system is based on a digital X-ray line detector, a 9 MV linear accelerator and a mechanism for rotating the canister. A test object consisting of a 70 degree sector of the electron beam (EB) welded lid-to-canister joint was used in the measurements. The test object has been equipped with several kinds of artificial defects, mainly in the weld asea. The smallest artificial defects are a groove of 0.5 mm cross-section extending 50 mm from the top of the weld to the root, a 1 × 1 × 1 mm3 cubic defect in the root and a flatbottom bore hole of diameter 1 mm and depth of 1 mm also in the root of the weld. These small defects are clarely observed in the X-ray pictures taken during the test program. Further, image quality indicators (IQI) of wire-, duplex wire-, hole- and step-hole types were used to compare the inspection results with European standards. The minimum requirements set by the standards was fulfilled, however, there are no minimum image quality values given for copper, so the corresponding values for steel were used (as recommended by the standard). The X-Rays project a picture of the weld on the line detector through a varying thickness of copper, therefore there is a risk that small defects may be unobserved if they happen to be situated in the shadow of a sharp thickness change of the copper wall. The presented results are, however, very encouraging and with some improvements in the detector-accelerator setup and in the image processing software are even better results than those presented in this work can be achieved.",
author = "Stefan Sandlin",
year = "2010",
language = "English",
series = "Working Report",
publisher = "Posiva",
number = "2009-84",
address = "Finland",

}

Defect detectability in the disposal canister lid-weld using the 9 MeV linear accelerator. / Sandlin, Stefan.

Posiva , 2010. 42 p. (Working Report; No. 2009-84).

Research output: Book/ReportReport

TY - BOOK

T1 - Defect detectability in the disposal canister lid-weld using the 9 MeV linear accelerator

AU - Sandlin, Stefan

PY - 2010

Y1 - 2010

N2 - The spent nuclear fuel will be placed in specially designed canisters, which consists of a cast iron insert with cannels for the fuel bundles and an outer corrosion barrier of copper with a wall thickness of 50 mm. The copper wall should meet the acceptance criteria regarding soundness of the weld. The canister to lid weld is a critical part in this aspect and it has to be inspected by non-destructive methods. The objective of this work was to investigate the defect detectability in the lid-to-canister weld using the high energy Xray system at SKB (Svenska Kärnbränslehantering AB) in Oskarshamn in Sweden. The system is based on a digital X-ray line detector, a 9 MV linear accelerator and a mechanism for rotating the canister. A test object consisting of a 70 degree sector of the electron beam (EB) welded lid-to-canister joint was used in the measurements. The test object has been equipped with several kinds of artificial defects, mainly in the weld asea. The smallest artificial defects are a groove of 0.5 mm cross-section extending 50 mm from the top of the weld to the root, a 1 × 1 × 1 mm3 cubic defect in the root and a flatbottom bore hole of diameter 1 mm and depth of 1 mm also in the root of the weld. These small defects are clarely observed in the X-ray pictures taken during the test program. Further, image quality indicators (IQI) of wire-, duplex wire-, hole- and step-hole types were used to compare the inspection results with European standards. The minimum requirements set by the standards was fulfilled, however, there are no minimum image quality values given for copper, so the corresponding values for steel were used (as recommended by the standard). The X-Rays project a picture of the weld on the line detector through a varying thickness of copper, therefore there is a risk that small defects may be unobserved if they happen to be situated in the shadow of a sharp thickness change of the copper wall. The presented results are, however, very encouraging and with some improvements in the detector-accelerator setup and in the image processing software are even better results than those presented in this work can be achieved.

AB - The spent nuclear fuel will be placed in specially designed canisters, which consists of a cast iron insert with cannels for the fuel bundles and an outer corrosion barrier of copper with a wall thickness of 50 mm. The copper wall should meet the acceptance criteria regarding soundness of the weld. The canister to lid weld is a critical part in this aspect and it has to be inspected by non-destructive methods. The objective of this work was to investigate the defect detectability in the lid-to-canister weld using the high energy Xray system at SKB (Svenska Kärnbränslehantering AB) in Oskarshamn in Sweden. The system is based on a digital X-ray line detector, a 9 MV linear accelerator and a mechanism for rotating the canister. A test object consisting of a 70 degree sector of the electron beam (EB) welded lid-to-canister joint was used in the measurements. The test object has been equipped with several kinds of artificial defects, mainly in the weld asea. The smallest artificial defects are a groove of 0.5 mm cross-section extending 50 mm from the top of the weld to the root, a 1 × 1 × 1 mm3 cubic defect in the root and a flatbottom bore hole of diameter 1 mm and depth of 1 mm also in the root of the weld. These small defects are clarely observed in the X-ray pictures taken during the test program. Further, image quality indicators (IQI) of wire-, duplex wire-, hole- and step-hole types were used to compare the inspection results with European standards. The minimum requirements set by the standards was fulfilled, however, there are no minimum image quality values given for copper, so the corresponding values for steel were used (as recommended by the standard). The X-Rays project a picture of the weld on the line detector through a varying thickness of copper, therefore there is a risk that small defects may be unobserved if they happen to be situated in the shadow of a sharp thickness change of the copper wall. The presented results are, however, very encouraging and with some improvements in the detector-accelerator setup and in the image processing software are even better results than those presented in this work can be achieved.

M3 - Report

T3 - Working Report

BT - Defect detectability in the disposal canister lid-weld using the 9 MeV linear accelerator

PB - Posiva

ER -

Sandlin S. Defect detectability in the disposal canister lid-weld using the 9 MeV linear accelerator. Posiva , 2010. 42 p. (Working Report; No. 2009-84).