Vallecitos: GE’s Boiling-Water Test Bed Reaches the Grid

GE-Hitachi-Prism-Reactor — U.S. Nuclear Regulatory Commission, Public domain, via Wikimedia Commons (https://commons.wikimedia.org/wiki/File:GE-Hitachi-Prism-Reactor.jpg)

Sourced history

A carefully defined first

The Vallecitos boiling water reactor, or VBWR, earned a specific place in nuclear history. ASME identifies it as the world’s first privately owned and operated nuclear power plant to supply significant quantities of electricity to a public utility grid. Between October 1957 and December 1963, it delivered approximately 40,000 megawatt-hours. That distinction is narrower than calling Vallecitos the first nuclear reactor connected to a grid: private ownership, private operation and significant electricity delivery are essential parts of the documented claim. The California plant combined electricity production with an experimental mission.

Sources: [3][4]

Sourced history

A partnership built on earlier research

Vallecitos was a collaboration between General Electric and Pacific Gas and Electric Company, with Bechtel acting as engineering contractor. GE engineer Samuel Untermyer was responsible for the reactor’s initial design. His work drew on conceptual research he had conducted at Argonne National Laboratory, including heat-transfer and nuclear-physics experiments and the BORAX boiling reactor experiment tests. The documented development story therefore extends beyond a single company: it includes Untermyer’s laboratory research, GE’s design contribution, a utility partner and an engineering contractor.

Sources: [3]

Sourced history

Electricity—and preparation for Dresden

The reactor used enriched uranium in plate-type fuel clad in stainless steel, with light water providing both moderation and cooling. It served as a pilot plant and testing ground for fuel, reactor-core components and controls. Personnel training was another explicit purpose, supporting Commonwealth Edison’s Dresden project in Illinois. Vallecitos thus had two documented roles: supplying electricity and providing facilities for testing and training associated with another nuclear power project. Its contribution was not limited to the megawatt-hours recorded during its operating period.

Sources: [3]

Sourced history

The boiling-water lineage

The central distinction between boiling water reactors and pressurized water reactors concerns where steam is produced. In a BWR, steam generated inside the reactor pressure vessel goes directly to the turbine generator. A PWR instead transfers heat to a separate water loop in a steam generator. The historical chronology preserved on the successor company’s reactor page places Vallecitos in 1957, the first Advanced Boiling Water Reactor’s entry into operation in 1996, and U.S. Nuclear Regulatory Commission certification of the Economic Simplified Boiling Water Reactor in 2014. These are separate milestones, not interchangeable measures of development.

Sources: [5]

Sourced history

From reactor development to a service business

By 2016, GE Hitachi Nuclear Energy described its business as the original equipment manufacturer of more than 60 boiling water reactors worldwide, servicing and supplying fuel to many operating BWRs. GE Hitachi had been established in June 2007 as part of a global nuclear alliance created by GE and Hitachi. In the 2016 announcement, president and CEO Jay Wileman invoked the project-management expertise and technical rigor expected by BWR customers while discussing the company’s first services outage at a pressurized water reactor facility.

Sources: [1]

Sourced history

Shutdown did not end the responsibility

Vallecitos shut down in 1963. A possession-only license followed in 1965 and was renewed in 1973; the facility was maintained in SAFSTOR condition. In 2022, the licensee submitted a Limited Post Shutdown Decommissioning Activities Report describing a change to active decommissioning. GE Hitachi then submitted a license termination plan on September 7, 2023. These records document a regulatory history extending long beyond the reactor’s electricity-producing years.

Sources: [4]

Commentary

Why Vallecitos matters to GE’s legacy

In our view, Vallecitos is most revealing when treated as more than a celebrated first. It offers a way to understand industrial innovation through partnership, experimentation, equipment testing and preparation of people. Its later regulatory history also encourages a fuller understanding of technological achievement: responsibility belongs in the story alongside invention and operation. For GE heritage, that balanced perspective is more valuable than an unqualified claim of priority.

Sources

[1] GE Hitachi Successfully Completes First Pressurized Water Reactor Outage with Exelon Generation at Ginna Nuclear Power Plant | GE News — ge.com
[3] Vallecitos Boiling Water Reactor - ASME — asme.org
[4] General Electric Co. – Vallecitos Boiling Water Reactor (VBWR) | Nuclear Regulatory Commission — nrc.gov
[5] Large nuclear boiling water reactor | GE Vernova Hitachi — GE Vernova

Written in original words with AI help from the sources above and automatically checked against them. Facts, quotations and commentary are labeled separately; credit belongs to the original authors. GE Heritage Village is independent and not affiliated with GE or Crotonville.