Lifetime prediction of an EPDM sealing component between dry and wet well in nuclear power plants
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Livslängdsuppskattning hos EPDM-tätning mellan dry- och wett-well i kärnkraftverk (Swedish)
Polymeric seals are widely installed in nuclear power plants. Since the seals are used to operational safety, it is very important to assess long-term behaviour.
In this study, the polymeric material used is Ethylene-Propylene-diene rubber (EPDM) because it has outstanding mechanical property and the characteristic of having high resistance to heat. An elevated temperature causes its ageing and therefore its degradation. It is great value that the condition of the seal is determined. This was achieved by studying samples that underwent accelerated ageing by different analytical methods; such as tensile testing, indenter modulus measurements, thermogravimetric analysis and infrared spectroscopy.
Two EPDM samples were examined which came from the Swedish nuclear power plant company OKG; one had been exposed for 3 years (EPDM aged) and the other one was unaged (EPDM unaged). The lifetime prediction was evaluated by Young’s modulus (the data increased with ageing time), strain at break (the values decreased as ageing is accelerated) and indenter modulus (the data followed the trend of Young’s modulus). From mechanical testing, there was not difference between EPDM unaged and aged. Therefore, the most important degradation is happened inside the oven at different temperatures. The mechanical data showed Arrhenius temperature dependence with activation energies at about of 50 kJ/mol for Young’s modulus and strain at break and of 40 kJ/mol for indenter modulus. These activation energies were used to extrapolate the lifetimes to dofferent temperatures (30°C, 40°C and 50°C). The composition of EPDM seal was determined by TGA and IR whereas the growing number of crosslinks was tested by density testing and swelling test.
Place, publisher, year, edition, pages
2011. , 62 p.
EPDM, Seals, Thermal Ageing, Mechanical Properties, Lifetime Prediction
IdentifiersURN: urn:nbn:se:kth:diva-40904OAI: oai:DiVA.org:kth-40904DiVA: diva2:442833
Subject / course
UppsokPhysics, Chemistry, Mathematics
Linde, ErikBlomfeldt, Thomas
Gedde, UlfHedenqvist, Mikael