Post irradiation examination of tight fit garter springs from Indian PHWR

Garter springs play an important role in maintaining the annulus gap between hot pressure tubes and cold calandria tubes of PHWRs. Post irradiation examination (PIE) was carried out on the garter springs removed from Indian PHWR after around 8 and 15 Hot Operating Years (HOY). PIE studies included visual examination, dimensional measurements, metallographic examination and relevant mechanical tests. The girdle wires of these garter springs were also examined and subjected to the tension and bend tests. This paper gives the results of the PIE investigations and discusses its relevance for continued performance of garter springs in PHWRs.