Dennis L Mangan

January 18, 1939 ~ September 28, 2020 (age 81)


Life well lived!  Well loved by many.

Dennis L. Mangan (Denny) began his life’s journey in Joliet, Illinois January 18, 1939 and crossed the finish line on September 28, 2020.  He was preceded in death by his first wife, Helen Kathleen Butterfield, and parents George and Marion Mangan.  He is survived by wife Diana Mangan, daughter Leslie Anyanonu (Stephen), son Michael Mangan; grandchildren Ben, Jordy, Gideon, Michal and Saoirse; step-daughters Heather Windish (Scott) and Jennifer Biringer (Kevin); brother George (Pat) Mangan, sister-in-law, Cathy Mangan; cousin Marilyn Miglin, and many nieces and nephews.

Denny graduated from the University of Notre Dame (where his dad also attended) in 1960 in electrical engineering. From Notre Dame, he came to Sandia National Laboratories (SNL) in Albuquerque NM, dedicating 41 years, retiring to consult another 9 years, leaving as a Senior Scientist. Through SNL he took advantage of advanced education opportunities, earning a Master’s Degree in electrical engineering and a Ph.D in nuclear engineering from UNM. His career was a reflection of the transition of the laboratories from a single mission supporting nuclear weapons development and Cold War issues to a broader portfolio in national security and engineering development.

His individual talent and education made him a natural contributor, beginning in 1973, with the development of the nation’s largest Research and Development program for the physical security of nuclear material at storage facilities and other military installations. Denny was a member of a small nucleus of exceptional scientists who established the safeguards and techniques for future standard approaches for decades in the world; this included the move from guard-based security to a protection technology-based security system pioneered at SNL.

He traveled to Russia to help oversee the transformation of its nuclear material security regime. He made an important contribution with the lead role in establishing the monitoring system for mobile missile production that Russia installed, and was instrumental in supporting other countries committed to eliminating intermediate range missiles from Europe. This was considered an historical achievement as a gateway to the end of the Cold War.

Denny achieved international expertise in nuclear safeguards, non-proliferation and arms control. He reflected a high standard of knowledge and competence with his achievements: SNL supervisor for the International Safeguards Division, in support of the Department of Energy and the Department of State programs providing assistance to the International Atomic Energy Agency (IAEA) and other international agencies; and Deputy Manager to the Director for Weapons Program. He responded to an urgent request by the Department of Defense and was responsible for installing the technical onsite inspection facility which became the benchmark for the Intermediate-Range Nuclear Forces Treaty (INF) negotiations. He was course director of Department of Energy (DOE/IAEA)  International Training Courses on the Physical Protection of Nuclear Facilities and Materials; Fissile Materials Disposition manager coordinating safeguards, robotics, and transportation; was principal author of the Global Nuclear Management strategic thrust; and one of two senior technical advisors for the US involvement in the exploration of excess fissile material inventory monitoring systems in support of a potential IAEA-Russia-US trilateral treaty.

Besides his first love for Notre Dame, his second passion was the Institute of Nuclear Materials Management (INMM), an international professional society. He served as a Vice President, President, Fellow, and for 18 years as the Editor of the Journal of Nuclear Materials Management (JNMM) for the Institute. He received 3 major awards given by the Institute: the Meritorious Service award, the Charles E. Petri Special Service award, and the Vincent J. DeVito Distinguished Service award. 

On his 79th birthday, the U.S. Southwest Professional Chapter of the INMM established the annual Dennis Mangan Student Award for the best student paper submitted to the INMM Annual Meeting from the US Southwest Region. Denny was dedicated throughout his career to the mentoring of students and was a contributor to the success of the INMM’s Student Chapters.

Denny was recognized as an expert and a highly regarded and respected leader in his field, providing insightful contributions and a clear vision for the future. In his free time, he enjoyed tinkering in the garage while watching his beloved Notre Dame football games. He loved to play golf and enjoyed camping and traveling.

The family wishes to thank Dr. Joy Lovette and Kristin Metz, R.N. of Hospice De La Luz for their loving care. At the Watermark at Cherry Hills, we wish to express our appreciation to all staff including Andrew, Linsey, Natalie, Rebecca, Karli, Sharon, Kristen, Patrick, Kevin, Cynthia, Naomi, Yami and Gloria, for their loving care in Denny’s final days. At the Morningstar, we wish to express our gratitude to his favorite caregivers including Lori, Valarie, Victoria, Kristin, Vickie, Odie,Elsie and Cheryl:

Mass will be celebrated on Friday October 16 at 11AM at The Prince of Peace Catholic Church, 12500 Carmel Avenue NE.  Social distancing and masks are required. There will not be a reception due to covid concerns.

Donations in his memory can be made to the INMM U.S. Southwest Professional Chapter, care of Daniels Family Funeral Home, 7601 Wyoming Blvd. NE, Albuquerque, NM, 87109. Donations will support student endeavors and the Dennis Mangan Student Award. Donations are not tax deductible.






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