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Gilbert Lenk Zigler was born in Rio de Janeiro, Brazil, in 1945. He was the son of Brazilian swimmer and World Record Holder, Maria Lenk Zigler, and Daniel G. Zigler, who was originally from Bisbee, Arizona. When he was 18 he moved to the United States to pursue a bachelor's degree in Electrical Engineering from the University of New Mexico. Upon graduation, he joined the United States Air Force and completed his master's in Nuclear Engineering through their Institute of Technology in 1969. After completing his master's, he continued with the USAF working on the safety analysis of the reactors housed in the Pioneer 10 and 11 deep space probes, which were launched in 1972 and 1973, respectively. Each probe contained four SNAP-19 radioisotopic thermoelectric generators (RTGs). These two space probes sought to achieve escape velocity in order to leave the solar system to encounter Jupiter and Saturn. Pioneer 10 and 11 laid the groundwork for the Voyager probes to study the outer solar system later that decade.

When Zigler left the USAF in 1973, he went to work for Babcock & Wilcox (B&W) as a reactor diagnostic engineer where he helped design and oversee the construction of seven different pressurized water reactors (PWRs). Two of these reactors were at the Three Mile Island Nuclear Generating Station. This began his career in the nuclear power industry, where he focused on the development of a noise and vibration monitoring system for reactors. When he left B&W in 1977, he continued his career working as a scientist at Science Applications Inc., located in Oak Ridge, Tennessee, and was eventually hired on with Science and Engineering Associates Inc., of Albuquerque, New Mexico in 1984.

A defining feature of his career was his involvement with the incident at the second unit at the Three Mile Island Nuclear Generating Station. On March 28, 1979, a cooling malfunction at the Three Mile Island Nuclear Generating Station triggered a partial core meltdown in the #2 reactor (TMI-II). The resulting emergency was later classified as the most significant accident in U. S. commercial power plant history, and registered as a "nuclear accident with wider consequences" on the International Nuclear Event Scale. The Three Mile Island Nuclear Generating Station consisted of two Babcock & Wilcox designed pressurized water reactors. Due to his experience with Babcock & Wilcox reactors, Zigler was called in to assess the problems at the Three Mile Island TMI-II reactor just hours after the reactor started malfunctioning. Zigler’s expertise with B&W reactors led to him providing a diagnosis for the malfunctioning unit and he contributed to the successful shutdown of the TMI-II reactor unit. After leaving Pennsylvania and with the encouragement of the director of the Division of Systems Safety of the Nuclear Regulatory Commission, Roger Mattson, Zigler put his thoughts and experiences at the reactor into words in “Recommendations for Improved Readiness for Future Nuclear Incidents.” He also co-authored “TMI-2 On-Site Monitoring and Diagnostic Measurements Using Noise Analysis,” the summary report for the President’s Commission on the Accident at Three Mile Island. The incident at TMI-II would continue to play a role in future publications and professional suggestions as he advocated for emergency response preparation.

Along with the reactors he helped develop with Babcock &Wilcox, Zigler also helped design the diagnostic systems in the Tokamak Fusion Test Reactor at the Princeton Plasma Physics Laboratory. This reactor contributed to the development of fusion technology. He also participated in six underground nuclear weapons tests including Pre-Direct Course, Diamond Beech, Mission Ghost, Misty Rain, and Minor Scale. He provided technical support to Tokyo Electric Power following the Fukushima Daiichi accident. As the reactors he had worked on aged, Zigler continued to play a role in diagnosing strainer clogging issues and assessing aging reactors.

His participation in professional organizations is notable. Zigler was a member of the American Society of Mechanical Engineers for almost 40 years. He was a charter member of ASME’s Vibration Monitoring subcommittee and Loose Parts Monitoring Subgroup, and served on the operations and maintenance committee helping to develop new and revised codes for the ASME. Certificates of professional commemoration underscore the role he played in the ASME and Symposium on Reactor Noise (SMORN). As a member of the Steering Committee for the Risk-Based Inservice Testing Research Project, he was commended for his “diligent service and unselfish devotion.” He received accolades for his help in the development of “Operation & Maintenance: Part 12, Loose Part Monitoring in LWR Power Plants.” In 2013, he was made a Fellow of ASME to recognize the exceptional engineering achievements and contributions he made to the engineering profession.