# Alternate Fracture Toughness Requirements for Protection Against Pressurized Thermal Shock Events
> **Nuclear Regulatory Commission** · Final rule. · Published 2010-01-04 · Effective 2010-02-03 · 75 FR 13
## Document
- **Document number:** E9-31146
- **Category:** other
- **Sub-agency:** Nuclear Regulatory Commission
- **Federal Register citation:** 75 FR 13
- **CFR reference:** 10 CFR 50
- **Publication date:** 2010-01-04
- **Effective date:** 2010-02-03
- **Energy docket:** NRC-2007-0008
## Abstract

The Nuclear Regulatory Commission (NRC) is amending its regulations to provide alternate fracture toughness requirements for protection against pressurized thermal shock (PTS) events for pressurized water reactor (PWR) pressure vessels. This final rule provides alternate PTS requirements based on updated analysis methods. This action is desirable because the existing requirements are based on unnecessarily conservative probabilistic fracture mechanics analyses. This action reduces regulatory burden for those PWR licensees who expect to exceed the existing requirements before the expiration of their licenses, while maintaining adequate safety, and may choose to comply with the final rule as an alternative to complying with the existing requirements.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2010/01/04/E9-31146/alternate-fracture-toughness-requirements-for-protection-against-pressurized-thermal-shock-events)
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