Research project

Advanced PTS Analysis for LTO (APAL)


Project Details
Start date: 01/10/2020
End date: 30/09/2024

European Commission


In the EU, most of the nuclear power plants (NPPs) are
currently in the second half of their designed lifetime, making lifetime
extension an important aspect for the EU countries. One of the most limiting
safety assessments for long term operation (LTO) is the reactor pressure vessel
(RPV) integrity assessment for pressurized thermal shock (PTS). The goal is to
demonstrate the safety margin against fast fracture initiation or RPV failure.
To verify safe operation of existing NPPs going through LTO upgrades, advanced
methods and improvements are necessary.

In the EU, currently used PTS analyses are based on
deterministic assessment and conservative boundary conditions. This type of PTS
analyses is reaching its limits in demonstrating the safety for NPPs facing LTO
and need to be enhanced. However, inherent safety margins exist and several LTO
improvements and advanced methods are intended to increase the safety margins
of PTS analysis. Additionally, the quantification of safety margins in terms of
risk of RPV failure by advanced probabilistic assessments becomes more important.

The main objectives of this project are establishing of
state-of-the-art for LTO improvements having an impact on PTS analysis: NPP
improvements (hardware, software, procedures), development of advanced
deterministic and probabilistic PTS assessment method including thermal
hydraulic (TH) uncertainty analyses, quantification of safety margins for LTO
improvements and development of best-practice guidance.

After establishing the LTO improvements, TH calculations
will be performed including also uncertainty quantification relevant to PTS
assessment. Benchmark calculations for both deterministic and probabilistic RPV
integrity assessment will be performed with the goal to establish the impact of
LTO improvements and TH uncertainties on the overall RPV integrity margins.

Nuclear related engineering, probabilistic, deterministic, integrity assessment, reactor pressure vessel, pressurized thermal shock, long term operation, initiation probability, uncertainty, benchmark, best practice.

LUT Focus Areas

Last updated on 2020-08-09 at 13:36

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