OVERVIEW OF THE HIGH-ENERGY LINE BREAK ASSESSMENT FOR CANDU REACTORS


11th International Conference on CANDU® Maintenance and Nuclear Components - 2017 Oct. 01-04

Presented at:
11th International Conference on CANDU® Maintenance and Nuclear Components
2017 Oct. 01-04
Location:
Toronto, ON Canada
Session Title:
Plant Performance

Authors:
G. Ozawa (Candu Energy Inc.)
X. Duan (Candu Energy Inc.)
M. Kozluk (Candu Energy Inc.)
M. Wang (Candu Energy Inc.)
Y. Shi (Candu Energy Inc.)
H. Wang (Candu Energy Inc.)
  

Abstract

Overview of the High-Energy Line Break Assessment for CANDU Reactors Gordon Ozawa, Xinjian Duan, Michael J. Kozluk, Min Wang, Yihai Shi, Hui Wang Candu Energy Inc, Mississauga, Ontario, Canada Gordon.Ozawa@Snclavalin.Com
CANDU Safety Issue CSI-IH6 is one of 16 design and analysis issues for Canadian CANDU® reactors [1]. CSI-IH6 is associated with Internal Hazards (IH) and in 2007 was originally categorized as a Category 3 issue, which are issues that are a concern in Canada and have measures in place to maintain safety margins, but the adequacy of these measures needs to be confirmed. The risk control measure for CSI-IH6 requires a systematic review of the dynamic effects (i.e., local effects from pipe whip and jet impingement) and environmental effects (e.g., humidity, temperature, radiation levels) of postulating high-energy piping breaks inside the reactor containment and identifying the consequences on plant safety, which may require potential design or process improvements. Candu Energy Inc. has performed such assessments for Bruce, Pickering, and the Point Lepreau Generating Station to support their request for the recategorization of CSI-IH6 from a Category 3 to a lower category. The purpose of the high-energy line break assessment (HELBA) is to systematically demonstrate that the design of the high-energy piping and safety systems inside the reactor building are in compliance with the best practices from modern industry standards and guidelines such as IAEA NS-G-1.11. Assessments of the high energy piping for the balance of plant have been performed for some units. Since its start in 2007, the HELBA methodology has dramatically evolved to address regulatory concerns, to adapt to unique station designs and layouts, and to meet specific client requirements. Some examples are presented in this paper. Most significantly, this work has assembled a qualified and experienced team that is capable of performing HELBA on operating stations and new designs.
[1] Canadian Nuclear Safety Commission, Canadian National Report for the Convention on Nuclear Safety - Seventh Report, Article 14 (i) (g), 2016 August.

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