Session: MF-05-02 Fitness-For-Service and Failure Assessment

Paper Number: 83766

83766 - Effect Of The Mean Temperature of Storage Site on Chloride-Induced Stress Corrosion Cracking Rate in ASME Code Case N-860: Case Study 

The spent nuclear fuels (SNFs) are disposed at Independent Spent Fuel Storage Installation (ISFSI) near seashores. During long-term storage of the canisters in dry cask storage system (DCSS), chloride-induced stress corrosion cracking (CISCC) can occur due to the deliquescence of concentrated salt on the canister surface. To evaluate such flaws on the accessible exterior metallic portions of containment systems while in service, ASME Code Case N-860 provides in-service inspection requirements for aging management of canisters manufactured with welded austenitic stainless steel. It is noteworthy that CISCC crack growth rate (CGR) model in Code Case N-860 consists of the constitutive equations with temperatures (surface, mean, and ambient) and independent of stress intensity factor or other environmental factors.
In this work, the effect of the canister surface temperature on the flaw grow rate by applying climates of four Nuclear Power Plants (NPPs) in South Korea is analyzed. Firstly, the CISCC CGR of the NPP site is calculated to compare each other in South Korea based on the ambient temperature data from Korea Meteorological Administration (KMA) when the surface temperature is assumed to be the same as the ambient temperature. After determining the site for evaluation where the largest crack growth is calculated, the climate data from 2011 to 2020 is applied to the CISCC CGR model and the annual CISCC depth rate is derived. Based on the calculated depth for a decade, the inspection interval is discussed to prevent through-wall cracking. Finally, the effect of increased surface temperature is assessed when the ventilation system of DCSS is assumed to be malfunction.

Presenting Author: Jae-Yoon Jeong Korea University

Presenting Author Biography: Master degree (2019) at Korea University<br/>Ph. D. Candidate at Korea University

Authors:

Jae-Yoon Jeong Korea University
Yun-Jae Kim Korea University
Poh-Sang Lam Fellow of ASME
Seunghyun Kim Korea Institute of Materials Science
Gi-Dong Kim Korea Institute of Materials Science