Nuclear scan of a mouse.
Nuclear scan of a mouse.

Nuclear Cambridge

Unless you read the yellow caution signs on the walls, the high-ceilinged chamber would appear to house a couple of ...
By Rebecca F. Elliott

Unless you read the yellow caution signs on the walls, the high-ceilinged chamber would appear to house a couple of drab concrete-walled rooms surrounded by a disorganized jumble of machinery, file cabinets, and multicolored plastic bins. But buried deep inside this apparent mess is a one and a half foot by two foot aluminum container that generates nearly six million watts of energy per second.

MIT’s Nuclear Reactor Laboratory, which has been in operation since 1958, runs a reactor that produces energy through the fission of highly-enriched uranium. It is one of the few university-run nuclear reactors in the United States, and is the hub of the Cambridge area’s experimental nuclear research. The laboratory’s powder blue containment dome—strong enough to withstand the head-on impact of a Boeing 747—is nestled between MIT’s academic buildings, a mere five minute walk from the Charles River. (The reactor is accessible via appointment, although the superintendent and associate directors declined to comment for this article.)

Back at Harvard, there’s no reactor. The University’s experimental nuclear research is located at the Medical School, where two-inch-long mice receive injections of radio-pharmaceuticals intended to reveal the presence of millimeter-wide tumors. At Harvard proper, the locus of nuclear operations is housed in offices in the depths of the Kennedy School devoted to managing the immense power present behind the closed doors of reactors like the one down Mass. Ave.

“We’re working with telephones and pieces of paper,” says Matthew Bunn, associate professor of public policy at the Kennedy School.

The papers are the last component of the Harvard-MIT nuclear triangle—another corner across the river at the Med school, another at the silent but potent reactor itself. This is the way Cambridge’s nuclear world exists: hidden in plain sight, quiet and unassuming.


Ninety-two protons, 92 electrons, and 143 neutrons. These particles are the components of uranium-235, an element that revolutionized science and transformed modern warfare. In the late 1930s and 40s, the United States invested billions in the Manhattan Project, a nuclear development program dedicated to researching highly-enriched uranium and developing the first atomic bomb.

Paul M. Doty, one of the last surviving participants in the Project, has remained involved in the field of nuclear research, turning his focus towards preventing nuclear war. The legacy of the Manhattan Project is a complicated one, its name forever tied to the destruction caused by Little Boy and Fat Man, the bombs that were detonated over Hiroshima and Nagasaki. In the aftermath of such destruction, in the midst of the Cold War, Doty founded what is now the Belfer Center for Science and International Affairs at the Harvard Kennedy School, in 1973.

“He wanted to create a center that was to train the next generation of people trying to reduce nuclear dangers,” says Matthew Bunn, associate professor of public policy at the Kennedy School.

The Belfer Center did just that, carrying on the tradition of nuclear cooperation and caution first called for by Albert Einstein and his associates in a manifesto published in 1955. The manifesto led to the first of the Pugwash Conferences on such issues, which continue to this day. Doty is the last living member of the founding Pugwash Conference.

Although the Belfer Center was established primarily to address nuclear threats, its focus has broadened over the years to include topics such as economics, climate change, and international relations. The division currently dedicated to nuclear policy research is titled “Managing the Atom” and focuses on nuclear energy as well as on nuclear terrorism and proliferation—concerns that have become more serious in the two decades since the Soviet Union collapsed.

“With the demise of the Soviet Union and the consequence—increased spread of nuclear weapons—nuclear proliferation became a more salient issue,” says William H. Tobey, a senior fellow at the Center whose primary task is to lead a U.S.-Russia initiative to reduce nuclear terrorism. He also teaches a course on nuclear arms control, “Controlling Weapons Proliferation,” which is one of very few classes on nuclear policy offered at Harvard.

The Soviet Union had tens of thousands of nuclear weapons, as well as a tremendous supply of highly-enriched uranium, according to Bunn, and in the 1990s there were a number of thefts of highly-enriched uranium and plutonium: bomb-making material. Additionally, the attacks on the World Trade Center on Sept. 11, 2001 raised global concern about terrorism, specifically nuclear attacks, and led to more aggressive international action in the Middle East to prevent proliferation.

“I think the greatest danger is that someone will become a weapons state. Another weapons state,” says Richard C. Lanza, a senior research scientist at MIT’s Department of Nuclear Science and Engineering.

In that vein, President Obama has taken a very proactive stance towards the spread of nuclear weapons. “Obama, during the campaign, said that we really ought to secure all nuclear material around the world within four years, and that was actually the goal that I had first proposed in these ‘Securing the Bomb’ reports,”  Bunn says. “Securing the Bomb” is a series of annual reports written by Bunn that discusses nuclear threats.

The proposal to locate and protect all vulnerable nuclear material was made official policy at the Nuclear Security Summit in Washington in April 2010. This agreement is one of the latest in a long string of nuclear treaties.

However, as Lanza points out, “One of our problems is treaties tend to be very, very explicit in technology choices.” As the technology used for weapons manufacture advances, treaties begin to become outdated.

“There’s a lot of technology out there to worry about,” Lanza says. He sighs. “To some extent, one could argue that once you get into the nuclear power industry, at least if you’re getting into the enrichment industry, then you can enrich further and make weapons.”


The forking paths of nuclear products are inherent even on the atomic scale. Uranium-235, rare in the natural world but essential to the manufacturing of nuclear weapons, is only used in small percentages for the harnessing of usable nuclear power. But uranium-238, its more naturally-occurring isotope, is the main component of low-enriched uranium, which is being looked to as a possible solution to the world’s energy crisis. Researchers across Harvard’s departments as well as at MIT’s Center for Advanced Nuclear Energy Systems (CANES) and Department of Nuclear Science and Engineering are trying to tackle the questions being raised about the future of nuclear energy.

With carbon emissions rising rapidly, developing energy sources other than coal and gas is becoming increasingly critical. “If you look at what’s likely to be needed, we probably need to reduce carbon emissions by 2050 compared to what they would be on a business-as-usual trajectory by something like 10-15 billion tons a year,” Bunn says.

At present, achieving this goal is nearly unthinkable. In practical terms, cutting just one billion tons in carbon emissions would require the construction of two million large windmills, or 700 large nuclear power plants on top of the number that are built every year on average. This would mean going from adding four reactors a year worldwide to adding 25 reactors a year until 2050. “There’s no possibility that we’ll do that in the next few years,” Bunn says.

This is due to a combination of factors, including the exorbitant price of nuclear power, the public perception of nuclear energy as decidedly dangerous, and the safety and security risks that are associated with nuclear power plants.

From an economic standpoint, developing nuclear energy is simply too expensive.  “Until there is a substantial price on carbon or much higher natural gas prices than there are today, or both, more likely, we’re not going to see private companies deciding to build a lot of nuclear power plants in the United States,” Bunn explains.

However, as Mujid Kazimi, Director of CANES, points out, remaining dependent on non-renewables such as coal or gas is not economically responsible either.

“If we were to turn completely from coal to actual gas, which is abundant at the moment, and relatively cheap, we could be setting ourselves up for a future where there could be quite a bit of economic consequences,” Kazimi says.

Price aside, increased investment in nuclear energy would have to come hand-in-hand with a positive change in the public’s perception of nuclear energy as well as the development of stronger security precautions. Especially in the wake of the explosion at the Fukushima Daiichi Nuclear Power Plant in Japan, nuclear energy can appear to be one of the most dangerous energy options available to us.

For nuclear power to become a viable option, “You’re going to have to have stronger measures for nuclear safety, stronger measures for nuclear security to protect against sabotage as well as the theft of nuclear material that could actually be used to make a nuclear bomb,” Bunn says.

Such stronger measures would include going beyond the safety inspections currently performed at nuclear reactor sites, as well as increased planning for how to handle potentially destructive natural disasters. “There is actually now quite a bit of confidence that we are able to handle almost all routine things in a safe manner,” Kazimi says. “The question always is whether the natural events are going to exceed the design values for these plants.”


An equally important safety concern, however, and one that is often left unmentioned, is how to handle nuclear waste. There are 104 nuclear reactors currently operating in the United States, according to Kazimi, and these reactors produce 20 percent of the country’s electricity. As Peter L. Galison, a professor of physics and history of science at Harvard, explains, “The two alternatives for nuclear waste from commercial nuclear plants is either to bury them in some way in a geological repository, or to put them in what are called dry casks after they have cooled down somewhat.”

In 2002, Congress approved Yucca Mountain, located in Nevada, as a geological repository for spent nuclear rods. However, the Obama administration canceled the project in 2009, a result of both technical and political pressures, Galison says. At the moment, there is no alternative plan for storage of radioactive material produced by commercial nuclear power plants.

There is one operating repository in the United States, the Waste Isolation Pilot Plant in Carlsbad, New Mexico, but this is only authorized to accept defense waste produced in the making of nuclear weapons.

“It’s irresponsible to continue to generate large amounts of nuclear waste when we have no national policy—nothing. We have no place to put it,” Galison says.

Perhaps more existentially troubling is the long-term consequences of nuclear waste storage. “Since the half-life of plutonium is 24,000 years, and you need many half-lives for it to become safe, how do you warn the future about the existence of repositories?” Galison asks. “How do you keep future generations from digging there looking for oil or gas?”


In 1920, nearly 10 years before the discovery of penicillin, the first nuclear medicine imaging was used to treat a person for cervical cancer, in Huntington Memorial Hospital in Boston, located where the Harvard School of Public Health now stands. Thus, radioactive isotopes—as opposed to the ones of uranium and plutonium buried in salt flats for 24,000 years—were found to have a place in medicinal science.

The field of nuclear medicine began taking off in the early 1960s, when it was discovered that iodine could be used to image the thyroid.

In today’s nuclear medicine research, short-lived radioactive elements are created using either research nuclear reactors or particle accelerators called medical-cyclotrons. These isotopes are then incorporated into various drugs or molecules to form radio-pharmaceuticals, which are then injected into the body for imaging or therapeutic purposes.

At the Harvard Medical School, individuals in the Joint Program for Nuclear Medicine (JPNM) are developing imaging agents to be used in PET and SPECT scans. PET, positron emission tomography, and SPECT, single-photon emission computed tomography, detect gamma rays emitted by injected radio-pharmaceuticals and record their location.

Ashfaq Mahmood, Associate Director of JPNM Radiopharmacy, has been developing imaging agents that reveal cancerous tumors in mice. In one set of SPECT images taken of a mouse’s lungs, tumors less than a millimeter in diameter appear in glowing vermillion.

There are perhaps only a dozen agents in nuclear medicine, says Amin I. Kassis, Director of the Radiobiology and Experimental Radionuclide Therapy Section of the Laboratory for Experimental Nuclear Medicine at Harvard. “It’s not for lack of trying, but it’s a complicated field.”

Kassis and his co-workers have been developing a thymidine analog that kills cancer cells. While the agent has not undergone significant clinical testing, it was used on a patient in France who had failed all therapies and was projected to die in three weeks. The thymidine analog prolonged her life eight months.

While the term ‘nuclear’ often arouses fears of damage caused by radioactivity, the doses used for imaging are so low that they are not thought to cause significant harm. “They don’t increase the possibility of developing cancer at a later time,” Kassis says. In fact, individuals can be exposed to higher doses of radiation during a dental or chest x-ray, or if they frequently fly in an airplane at high altitudes.

Therapeutic agents, which are meant to treat disease, are given in higher doses and remain in the body for a longer time period. This does slightly increase the patient’s risk for developing cancer, “But you do it because you’re trying to save a patient’s life,” Kassis says.

However, the negative connotations of the word ‘nuclear,’ which is usually associated with weapons or power generation, are still a serious hurdle for nuclear medicine. There is currently a push to change the name of the field from nuclear imaging to molecular imaging, Mahmood explains.

“It gets rid of the word nuclear,” says Robert Zimmerman, Director of Physics and Engineering Services in the JPNM. “It has bad connotations.”

Indeed, in 1963, Harvard professor and surgeon Francis D. Moore graced the cover of Time Magazine for his pioneering work using radioactive isotopes to map the composition of the human body. The hopeful tagline read, “If they can operate, you’re lucky.” But the Time cover most people remember remains the July 1, 1946 edition, featuring Einstein’s creased face with a brilliantly colored mushroom cloud in the background. That tagline said, “All matter is speed and flame”: together, revealing both sides of the nuclear coin.