Pressurized thermal shock PTS

SI method Regulation Screening criteria Type of analysis Key details of analytical approach 

Russia General rules of PNAE-G-7-008-89 None Primarily deterministic, but probabilistic can be used Semi-elliptical surface flaws up to ]i-Tdepth with length = %-7 initiation only with no safety factor on /Cic cladding effects considered no benefit for warm prestressing Pf 1 x 10 Vreactor year, if used 

France General rules of RCC-M, Appendix ZG None Deterministic Combination of flaw sizes and safety factors depending upon transient categories cladding effects considered no benefit of warm prestressing crack arrest allowed only for 4 category transients 

Japan JEAC 4206 Simplified generic method of a comparison with Ktc curve Deterministic Size of semi-elliptic surface flaw approximately two times reliably detectable flaw depth with length six times the depth cladding effects to thermal analysis considered no benefit of warm prestressing 

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Loss of coolant accidents (LOCAs) as initiators of pressurized thermal shock (PTS). 

Another important project is the pressurized thermal shocks (PTS). Different cases of involving a break of main steam header (MSH) and steamlines, both at nominal power and at zero power were analysed. 

The pressurized thermal shock (PTS) problem has been for a long time under scrutiny by the safety specialists. In practice, in case of accident (e.g. a LOCA), a quick refrigeration of the primary water (and therefore of the vessel wall) takes place, either because of the depressurization following the accident or because of the emergency cold water injection. Under these conditions, the presence of cracks in some areas of the vessel (e.g. near the inlet nozzles of the vessel itself), combined with inadequate ductility of the material, might create critical situations from the structural point of view (unstable crack propagation). 

Irradiation embrittlement in RPVs mainly results in two consequences. First, it narrows the pressure-temperature operation window for normal operating conditions. Second, it limits RPV lifetime as the transition temperature of RPV materials cannot be higher than that determined from the pressurized thermal shock (PTS) calculations. Several mitigation measures can be applied to decrease radiation embrittlement of RPV beltline materials ... 

The US NRC was developing the Pressurized Thermal Shock (PTS) Rule at the same time that Revision 2 of Regulatory Guide 1.99 was being revised. The original PTS Rule was based on an intermediate embrittlement correlation on a slightly smaller database before Revision 2 of the... 

EricksonKirk, M. and Dickson, T. (2010) Recommended Screening Limits for Pressurized Thermal Shock (PTS), March, NUREG-1874, US Nuclear Regulatory Commission, Washington, DC. 

Specific plant data in the area of vessel resistance to pressurized thermal shock (PTS) (e.g. to specify the acceptable vessel cooldown rate) ... 

In addition to the licensee responses to GL 92-01, the following documents were included in die review process and development of the RVTD surveillance capsule reports, documents referenced in the GL 92-01 submittals, and, as applicable, pressurized thermal shock (PTS) submittals, P/T limite reports and responses to NRC staff requests for additional information (RAI). The staff reviewed the data from these source documents and documented them in the RVID tables. Responses to the close-out letters to GL 9201 are not necessarily reflected in this version, but will be included in a future version of the RVID. Revision 1 of the RVID and the RVID user s manual will be available on the NRCs world wide web homepage at http //www.nrc.gov/. The target date for availability of the database is June 1996. To access the homepage one must have an Internet account and a web browser. 

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