According to a partially redacted justification notice posted online last week, the US Air Force said that it was awarding Boeing the sole-source contract because “this procurement and sustainment activity is critically needed to replenish the inventory of GBU-57’s, ended during Operation Midnight Hammer (21 June 25).”

Boeing is the only company that makes the GBU-57 Massive Ordnance Penetrator, and the justification notice is intended to explain why the Pentagon did not carry out a fully competitive tender for the specially designed munition.

The exact number of BGU-57s being purchased and the cost of the contract, along with delivery dates, were not published.

An Air Force fact sheet described the MOP as “a weapon system designed to accomplish a difficult, complicated mission of reaching and destroying our adversaries’ weapons of mass destruction located in well-protected facilities.”

Weighing 30,000 pounds (13,600 kilograms), with the warhead alone weighing 5,740 pounds (2,600 kg) and measuring over 20 feet (6 meters) in length, the MOP can penetrate up to 200 feet  (60 m.) of earth or 60 feet (18 m.) of reinforced concrete, making it the most powerful non-nuclear bomb in the US arsenal.

According to a report in Scientific American, the kinetic strike “delivers 800 to 900 megajoules (about 758,000 to 853,000 British thermal units) of kinetic energy – comparable to a 285-ton (285,000 kg.) Boeing 747-400 touching down at 170 mph (274 kph) or a 565-ton (565,000 kg.) Amtrak Acela train moving at 120 mph (193 kph).”

While US officials hailed the mission as a success, independent assessments suggested mixed results. Fordow reportedly suffered severe damage, but Natanz and Isfahan may recover faster than anticipated.

The operation highlighted both the strengths and limitations of the MOP, particularly its massive size as well as its limited aircraft compatibility, the challenge of penetrating ultra-hardened targets, and Iran’s continued development of sophisticated defenses.

The agencies partnered with California-based Valar Atomics to fly one of the company’s Ward microreactors on a C-17 aircraft, without nuclear fuel, to Hill Air Force Base in Utah.

Energy Secretary Chris Wright and Under Secretary of Defense for Acquisition and Sustainment Michael Duffey were on the C-17 flight with the reactor and its components, and hailed the event as a breakthrough for US nuclear energy and military logistics.

The Energy Department in December issued two grants to help accelerate the development of small modular reactors.

“There is no business case for microreactors, which, even if they work as designed, will produce electricity at a far higher cost than large nuclear reactors, not to mention renewables like wind or solar,” said Edwin Lyman, director of nuclear power safety at the Union of Concerned Scientists.

The Energy Department plans to have three microreactors reach “criticality,”  when a nuclear reaction can sustain itself, by July 4, Wright said.

The microreactor in Sunday’s event, a little larger than a minivan, can generate up to 5 megawatts of electricity, enough to power 5,000 homes, according to Valar CEO Isaiah Taylor. It will start operating in July at 100 kilowatts and peak at 250 kilowatts this year before ramping up to full capacity, he said.

Valar hopes to start selling power on a test basis in 2027 and become fully commercial in 2028. Although private industry funds its own development of nuclear technology, it also needs the federal government “doing some enabling actions to allow fuel fabrication here and uranium enrichment here,” he said.

Fuel for Valar’s reactor will be transported from the Nevada National Security site to the San Rafael facility, Wright told reporters.

However, even small generators result in a significant amount of radioactive waste, Lyman said. Other experts have said designers are not compelled to consider waste at inception, beyond a plan for its management.