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POSIVA Report 1998-3

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Name:

EB-Welding of the Copper Canister for the Nuclear Waste Disposal Final Report of the Development Programme 1994-1997

Writer:

Harri Aalto

Language:

English

Page count:

44

ISBN:

951-652-041-3; 1239-3096

Summary:

Working report: POSIVA-raportti POSIVA 98-03, 43 sivua
ISBN 951-652-041-3


EB-WELDING OF THE COPPER CANISTER FOR THE NUCLEAR WASTE
DISPOSAL - FINAL REPORT OF THE DEVELOPMENT PROGRAMME 1994-
1997


ABSTRACT

During 1994-1997 Posiva Oy and Outokumpu Poricopper Oy had a joint project
“Development of EB-welding method for massive copper canister manufacturing”. The
project was part of the national technology program “Weld 2000” and it was supported
financially by Technology Development Centre (TEKES).

The spent fuel from Finnish nuclear reactors is planned to be encapsulated in thick-
walled copper canisters and placed deep into the bedrock. The thick copper layer of the
canister provides a long time corrosion resistance and prevents deposited nuclear fuel
from contact with water. The quality requirements of the copper components are high
because of the designed long lifetime of the canister. The EB-welding technology has
proved to be applicable method for the production of the copper canisters and the EB-
welding technique is needed at least when the lids of the copper canister will be closed.

There are a number of parameters in EB-welding which affect weldability. However, the
effect of the welding parameters and their optimization has not been extensively studied
in welding of thick copper sections using conventional high vacuum EB-welding. One
aim of this development work was to extensively study effect of welding parameters on
weld quality. The final objective was to minimise welding defects in the main weld and
optimize slope out procedure in thick copper EB-welding.

Welding of 50 mm thick copper sections was optimized using vertical and horizontal
EB-welding techniques. As a result two full scale copper lids were welded to a short
cylinder successfully. The resulting weld quality with optimised welding parameters
was reasonable good. The optimised welding parameters for horizontal and vertical
beam can be applied to the longitudinal body welds of the canister. The optimal slope
out procedure for the lid closure needs some additional development work.

In addition of extensive EB-welding program ultrasonic inspection and creep strength of
the weld were studied. According to investigations the creep strength of the copper
material is sufficient for repository conditions. The ultrasonic inspection of the weld is
very challenging because of large and orientated grain structure of the material. Some
additional work is needed to optimise the material grain structure and ultrasonic probes
which will be used in full scale canister inspection.

The whole research work confirm the applicability of copper as a canister material and
gives good basis on manufacture of full size canisters applying EB-welding technique.
Keywords: mechanical excavation, cuttability, drillability


Keywords: EB-welding, copper canister, nuclear fuel disposal


POSIVA-raportti POSIVA 98-03, 43 sivua
ISBN 951-652-041-3


EB-WELDING OF THE COPPER CANISTER FOR THE NUCLEAR WASTE
DISPOSAL - FINAL REPORT OF THE DEVELOPMENT PROGRAMME 1994-
1997


ABSTRACT

During 1994-1997 Posiva Oy and Outokumpu Poricopper Oy had a joint project
“Development of EB-welding method for massive copper canister manufacturing”. The
project was part of the national technology program “Weld 2000” and it was supported
financially by Technology Development Centre (TEKES).

The spent fuel from Finnish nuclear reactors is planned to be encapsulated in thick-
walled copper canisters and placed deep into the bedrock. The thick copper layer of the
canister provides a long time corrosion resistance and prevents deposited nuclear fuel
from contact with water. The quality requirements of the copper components are high
because of the designed long lifetime of the canister. The EB-welding technology has
proved to be applicable method for the production of the copper canisters and the EB-
welding technique is needed at least when the lids of the copper canister will be closed.

There are a number of parameters in EB-welding which affect weldability. However, the
effect of the welding parameters and their optimization has not been extensively studied
in welding of thick copper sections using conventional high vacuum EB-welding. One
aim of this development work was to extensively study effect of welding parameters on
weld quality. The final objective was to minimise welding defects in the main weld and
optimize slope out procedure in thick copper EB-welding.

Welding of 50 mm thick copper sections was optimized using vertical and horizontal
EB-welding techniques. As a result two full scale copper lids were welded to a short
cylinder successfully. The resulting weld quality with optimised welding parameters
was reasonable good. The optimised welding parameters for horizontal and vertical
beam can be applied to the longitudinal body welds of the canister. The optimal slope
out procedure for the lid closure needs some additional development work.

In addition of extensive EB-welding program ultrasonic inspection and creep strength of
the weld were studied. According to investigations the creep strength of the copper
material is sufficient for repository conditions. The ultrasonic inspection of the weld is
very challenging because of large and orientated grain structure of the material. Some
additional work is needed to optimise the material grain structure and ultrasonic probes
which will be used in full scale canister inspection.

The whole research work confirm the applicability of copper as a canister material and
gives good basis on manufacture of full size canisters applying EB-welding technique.
Keywords: mechanical excavation, cuttability, drillability


Keywords: EB-welding, copper canister, nuclear fuel disposal


Keywords:

EB-welding; copper canister; nuclear fuel disposal

File(s):

EB-Welding of the Copper Canister for the Nuclear Waste Disposal Final Report of the Development Programme 1994-1997 (pdf) (2.3 MB)


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