CAMBRIDGE, Mass.--The MIT Nuclear Reactor Laboratory is a trip into the past and, if nuclear power grows in this country, perhaps a glimpse into the future.

A stone's throw from busy Massachusetts Avenue here is a large blue cylinder about the height of a two-story building, which houses the reactor, built with an attached research lab in 1958 at the dawn of the nuclear power industry.

The mission of the lab has changed over the years, most recently shifting its primary emphasis from medical research to experiments on new materials and fuels for nuclear power. Its director envisions that the lab's main product--streams of neutrons--could be used to advance microscopic imaging, giving researchers the ability to visualize the structure of proteins or the inside of complex machines.

All the while, the building is a training ground for nuclear engineering students from the Massachusetts Institute of Technology, giving them hands-on experience with the various aspects of nuclear power, from a basic understanding of how a reactor works to nuclear plant safety.

Superintendent Edward Lau gave me a tour of the reactor earlier this week, which I had heard of and passed dozens of times but had never seen up close. In addition to satisfying my curiosity, I was also looking for clues on the future of nuclear power in the U.S. and whether this was possibly an outpost in the hoped-for nuclear renaissance in the U.S., spawning new reactor designs such as modular reactors placed close to city centers.

Old school In many ways, the lab itself is quaint and old-fashioned. At the check-in desk, there's all sorts of analog equipment from an earlier time, including a typewriter and large board with hand-operated switches that light up to show who is in the reactor at any time, a security measure that works even if the power's out.

Rather than an electronic radioactivity monitor, visitors carry a pen-like device with a filament inside that reacts to changes in electrical charge to measure any radioactivity. When you walk out, a classic Geiger counter, giving off a regular stream of crackling beeps, makes sure your hands or shoes are clean of contaminants.

Inside the containment building is a collision of the old and new again. To get into the building, you have to pass through two air-tight doors that have a balloon seal of special reinforced rubber around the edges, the same type used in submarines.

Once inside, you can see the structure that holds the actual reactor, which at its core is only 15 inches across. It's puny in terms of output, too, able to generate five megawatts of thermal power, compared to 1,000 megawatts or more of electric power (or about 3,000 megawatts of thermal power) from a commercial nuclear power plant. The current reactor was installed in 1975 and it uses a more highly enriched version of uranium fuel than a commercial plant.

The core sits inside a tank of heavy water, which has a form of hydrogen atoms that reflect neutrons from the core back as slower-moving "thermal neutrons" to maintain the chain reaction, Lau explained. That tank of water sits inside a tank of graphite, which reflects neutrons. And all of that is surrounded by a cylindrical concrete structure, made with special, iron-laden concrete and covered with steel.

The heat from the MIT reactor could supply enough heat for the lab and an adjoining building, but the university decided not to do that because it represents a conflict of interest, Lau said. After all, if you have to immediately shut down the reactor for a safety reason, it wouldn't be a reliable heating system.

Instead of usable energy, the reactor from the start was designed to generate a stream of neutrons for experimentation. The neutrons come out of "beam ports," or small tunnels where neutrons shoot out from the core. Those captured neutrons are used for a wide range of experiments, done both by MIT students and outsiders who use the facility.

In the early days of the 1950s, the research was quite basic: engineers needed to better understand nuclear fission, or splitting atoms, to release heat in a controlled way. The center has since done research in many areas, including semiconductors, and working for utilities seeking better power plant design.

In the 1990s, the lab did quite a bit of work on boron neutron capture therapy, where cancer patients would sit in a room next to one of the beam ports and receive a dose of radiation. Patients would take a treatment that includes boron, which interacts with the neutron beam, releasing enough energy to kill cancer cells.

Fitting in and looking ahead Now, one of the areas that the lab is focused on is in-core experiments, something that's very specialized and requires specific engineering expertise, according to Lin-wen Hu, the associate director of research development. While some university research nuclear reactors in the U.S. shut down because of lack of funding in the 1990s, there is now more research money available from the Department of Energy, she added.

Working with the Idaho National Laboratory, the research reactor is used to expose different materials and fuels to the radiation of an actual core. Although the MIT research reactor core operates at only 50 degrees Celsius, researchers can insert a loop, or tube, that's about two inches in diameter into the core and control the heat and pressure for experiments, Hu explained.

Although the reactor has been in Cambridge for decades, relations between MIT and the city have been strained at times. Following the September 11 attacks in 2001, the city council held emergency hearings to gain assurances regarding the safety of the operation.

In 2005, an ABC News investigation found security lapses in some of the country's research reactors, prompting more hearings in Cambridge regarding safety. Another cause for unease is the fuel used at the reactor, which uses fuel that has a higher concentration of enriched uranium than commercial plants.

MIT has committed to changing by 2015 to a different fuel type now being developed that has a lower concentration of enriched uranium, making it harder to convert to a bomb, said Thomas Newton, the associate director of engineering. It's taking years because the fuel and fuel casing, or cladding, needs to be tested for durability and ability to withstand conditions in the core, he said.

Community relations are a significant part of what the reactor lab does, Lau indicated. It regularly gives tours, including to high-school students, and has meetings with city officials, including fire and police officers, he said.

Even as the lab continues trying to be a good neighbor tucked in the city, its director David Moncton has ideas on how to expand, either by hosting more experiments from others with a larger reactor or by breaking into new areas. One idea is testing out salts that could be used as a core coolant, rather than water, which could be used in a new generation of reactors, he said.

Meanwhile, students learn the ins and outs of nuclear power and can get certification from the Nuclear Regulatory Commission for their work. When I was in the control room, I met MIT junior and nuclear engineering major Brendan Ensor and asked whether his learning there would prepare him for the nuclear renaissance in the U.S. His response "That's the plan."