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Nuclear Nonproliferation Policy
The mission of the Nuclear Nonproliferation Policy Division (NNPD) is to promote the peaceful use of nuclear technology while simultaneously preventing the diversion and misuse of nuclear material and technology through appropriate safeguards and security, and promotion of nuclear nonproliferation policies. To achieve this mission, the objectives of the NNPD are to: Promote policy that discourages the proliferation of nuclear technology and material to inappropriate entities. Provide information to ANS members, the technical community at large, opinion leaders, and decision makers to improve their understanding of nuclear nonproliferation issues. Become a recognized technical resource on nuclear nonproliferation, safeguards, and security issues. Serve as the integration and coordination body for nuclear nonproliferation activities for the ANS. Work cooperatively with other ANS divisions to achieve these objective nonproliferation policies.
Meeting Spotlight
International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2025)
April 27–30, 2025
Denver, CO|The Westin Denver Downtown
Standards Program
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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Latest News
TerraPower begins U.K. regulatory approval process
Seattle-based TerraPower signaled its interest this week in building its Natrium small modular reactor in the United Kingdom, the company announced.
TerraPower sent a letter to the U.K.’s Department for Energy Security and Net Zero, formally establishing its intention to enter the U.K. generic design assessment (GDA) process. This is TerraPower’s first step in deployment of its Natrium technology—a 345-MW sodium fast reactor coupled with a molten salt energy storage unit—on the international stage.
Paul David Bottomley, Michel Coquerelle
Nuclear Technology | Volume 87 | Number 1 | August 1989 | Pages 120-136
Technical Paper | TMI-2: Materials Behavior / Nuclear Safety | doi.org/10.13182/NT89-A27642
Articles are hosted by Taylor and Francis Online.
Samples of the bores obtained from the melted core of the Three Mile Island Unit 2 (TMI-2) reactor were investigated as part of the TMI-2 accident evaluation program. The samples included fuel rod segments, control rod cladding, melted core rocks, and powder debris from various bores into the reactor core. The microstructure of the specimens was determined by examination and analysis of surface and cross section by means of electro-optical techniques (including energy-dispersive X-ray scanning electron microscopy and microprobe analysis). Gamma spectroscopy and a fission product release study were also performed on the specimens. The melted core rock specimens obtained from the G12 bores were mostly porous ceramic mixtures of uranium and zirconium oxides in the form of a fine eutectic of UO2- and ZrO2-rich phases and oxidized ferrous material derived from the stainless steel components. The rock specimens showed variations in porosity and ferrous content but a similar UO2-ZrO2 eutectic structure. Fission product analysis of the fuel segments and rocks indicated relatively low levels of activity due to fission products such as I37Cs, 106Ru, I54Eu, and fuel irradiation products. No volatile 129I was detected, but most other products displayed some retention in the melted core samples. According to whether eutectics were formed between Zr(O) and UO2 or ZrO2 and UO2 (i.e., the oxygen potential in the core), reference to the phase diagrams suggests temperatures of 2173 to 2873 K (1900 to 2600°C) for substantial periods and even up to 3073 K (2800°C) (U02 melting point) for the completely melted core specimens. Agglomerate specimens indicate lower temperatures [∼1673 K (1400°C), the melting point of stainless steel] and shorter excursion times at the edge of the melt zone. The remaining fuel rod segments showed very little change, indicating that the severe overheating is localized to the central part of the reactor pile.
