United States Nuclear Regulatory Commission - Protecting People and the Environment

Reactor Vessel Integrity

Reactor pressure vessels, which contain the nuclear fuel in nuclear power plants, are made of cylindrical shell courses with a welded hemispherical bottom head and a removable hemispherical upper head. The shell courses are fabricated from thick steel plates or ring forgings that are welded together. When the reactor is operated, neutron radiation from the reactor core causes embrittlement of the reactor vessel. Embrittlement refers to a decrease in the fracture toughness of reactor vessel materials and affects the vessel materials in the section closest to the reactor fuel, referred to as the vessel’s "beltline."

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Source of the Information

As a result of its review of licensee responses to Generic Letter 92-10, the NRC staff developed a comprehensive database to compile and record summaries of the material properties for the reactor vessel beltline materials for each plant.  This database is known as the reactor vessel integrity database (RVID).  The RVID contains data up to approximately the year 2000 and fracture toughness projections to the end of the original 40-year operating license.

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The staff uses the RVID to efficiently access plant-specific data and information submitted through approximately the year 2000, pertaining to reactor vessel integrity.

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Access to the Data

Staff. The RVID has not been updated since 2000.

Public. For ease of distribution to licensees and the public, the database is provided as a Microsoft  Excel spreadsheet via the RVID page.

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Last Update

The RVID data was last updated in July 2000. There are no current plans to update RVID.

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Related Reactor Materials Embrittlement Data

Consistent with our Open Government Plan, the NRC has issued a high-value dataset (with accompanying data dictionary) to expand the public's knowledge about the agency's oversight of operating reactor facilities, as it relates to embrittlement of reactor pressure vessel materials. Irradiation embrittlement is a phenomenon that occurs as a consequence of reactor operation when neutrons from the nuclear fuel irradiate the thick steel plates and welds used to construct the vessel. This irradiation embrittles the steel, making it less tough and, therefore, less capable of maintaining structural integrity in the presence of flaws that may exist following fabrication. (For additional detail, see the Fact Sheet on Reactor Pressure Vessel Issues.) The NRC obtains information on irradiation embrittlement from surveillance capsule reports obtained through the Reactor Vessel Material Surveillance Program conducted under Appendix H to Title 10, Part 50, of the Code of Federal Regulations (10 CFR Part 50). Information from these surveillance capsule reports is summarized in the RVID, along with information from other sources.

Available in open format (Microsoft Excel), this Reactor Materials Embrittlement Dataset provides access to information on surveillance capsule reports, which include reactor materials embrittlement data from the Nation's fleet of operating nuclear power reactors. Specifically, this dataset lists each plant name and reactor type, designer, and manufacturer. It also states the plant's license term, the date on which the operating license will expire, and whether the plant was licensed to operate as of January 1, 2011. In addition, the dataset provides the PDF filename for the plant's surveillance capsule report, along with the report date and identification of the specific surveillance capsule. The related Data Dictionary explains each field in the dataset and provides instructions for accessing the surveillance capsule reports.

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Page Last Reviewed/Updated Wednesday, August 09, 2017