Hantering av skadade styrstavar

Sammanfattning

The thesis was performed at Forsmarks Kraftgrupp AB in the department of

mechanical engineering, FTCM.

Forsmark nuclear power plant has had problems with cracks in some of the control

rods which are placed in the reactor at Forsmark 3. To investigate the cause of this,

material samples were taken from five of the damaged control rods. This sampling of

the rods resulted too short rods to be transported in the shipping container to the

interim storage facility for used nuclear fuel in Oskarshamn.

Control rods are crucial components in a nuclear reactor, regulating the reactor

effect by blocking or unblocking fuel rods. Control rods which have been in the

reactor are always handled under water in order to protect against the radiation they

emit.

The task was to design a control rod adapter that extends the control rod so

transport can be performed from Forsmark. The goal of the work was a complete set

of blueprints so the control rod adapter can be manufactured and mounted on the

short control rods and then be transported to the interim storage facility.

The work began with mapping of how control rods normally being handled from the

reactor to the interim storage facility. With the mapping as a basis, a requirement

specification was made. From the specification and the information from the mapping

different concepts were sketched. The concepts were evaluated and improved to a

final concept, which was then drawn up with the CAD-program Inventor. Materials

for the various features were selected and calculations were performed in

calculation-program ANSYS 13.0. Finally, blueprints were produced of the control rod

adapter.

The control rod adapter meets the requirement specification. It is easy to mount and

has a robust design. A prototype should be manufactured to enable practical testing

to verify that the control rod adapter works as planned.