The End of an Era:

The Uranium is Gone

December 2000

The uranium arrives at VU

In 1958 Profs. Manuel Bretscher and Armin Manning, co-chairs of the VU Physics Department, accepted a shipment of 2,500 kg (5,500 lb) of natural uranium enclosed in 1,425 "slugs". (The paperwork for this transaction is still in the Department files.) The uranium was received from the U.S. Atomic Energy Commission (AEC) on an indefinite loan to the University. [The AEC was eventually divided into what would become known as the Department of Energy (DOE) and the Nuclear Regulatory Commission (NRC), the former with the mission of promoting the use of nuclear energy, and the latter charged with the enforcement of the strict regulations on the use of nuclear materials.]

The uranium leaves VU

Forty-two years later, in December 2000, all 1,425 uranium slugs were shipped back to the Department of Energy and the nuclear reactor instructional program at VU was ended, likely forever. The reasons for this action are described below. But, first some context.

Some history and background

In the late 1950's the AEC was promoting programs such as the one at VU: the AEC would provide the Uranium for use in a sub-critical assembly and the University would provide for its safe use. It was the hope that in so doing, increasing numbers of college students would graduate prepared to move into the nuclear power industry. And, so it was for VU . Over these years, many students have graduated and pursued careers in the nuclear power industry and/or in the U.S. Navy reactor program.

The program to use the uranium in a sub-critical assembly (reactor) began in 1958 in the basement of Baldwin Hall, the former home of the Physics Department. In 1976 the uranium was moved from Baldwin Hall to the Neils Science Center upon completion of the Klingsick addition which houses the Physics and Astronomy Department. The new facilities which included a large room with 5-foot thick walls was well suited to the reactor use for the succeeding fifteen years. Much more nuclear physics laboratory experimentation is done in this excellent laboratory facility.

The nuclear reactor or sub-critical assembly

The uranium-filled slugs delivered to VU were concentric cylinders of aluminum, approximately 1-inch outer diameter and 3/8-inch inner diameter and approximately 8-inches long. The uranium was packed between these cylinder walls and the two cylinders were closed at the ends with welds. In this way, the uranium was contained in the slugs and was not in contact with any of the surroundings and was safe to handle. The radiation from the slugs was not harmful, even for fairly extended exposures.

To operate the sub-critical assembly (nuclear reactor) in the Physics Department, six slugs each were stacked into 6-foot-long aluminum tubes and the tubes were then placed vertically into a "matrix" in the reactor tank. The cylindrical steel tank was 6-feet in diameter and 6-feet deep and was filled with 1,350 gallons of de-ionized tap water. To transform this completely benign system into a fission chain-reacting nuclear reactor, a source of neutrons was placed at the center of the assembly of tubes in the water. The power of the system was determined by the natural uranium, the "light" water (not "heavy water"), various geometric considerations, and the number of neutrons per second from the sources in the center. The result was a very low-level chain reaction which generated enough power to light one flashlight bulb - if you could get the power out in the form of heat and convert it to electricity. (The water in the reactor never rose above room temperature due to these low power levels.) The power was maintained at these low levels to assure the safe operation of the system as an ideal teaching tool. Moreover, because of the low fission levels, the uranium fuel was only minutely depleted and the number of fission fragment nuclei from these fission reactions, which would provide sources of radiation from the fuel, was likewise very small. The result was that the fuel served our instructional needs for all of these years since 1958!

The U.S. nuclear power industry declines

Many of you will recall the activism of the late 1960's and 1970's and beyond which protested the use of nuclear energy in the U.S. The result was the effective demise of the nuclear power industry in the U.S. and along with this the job opportunities likewise diminished. Accordingly fewer students were interested in the nuclear power industry as a career path and the need for instruction in reactor and fission physics waned. Given the number of interesting topics in nuclear (and particle) physics that students could study, the Reactor Physics course of the 1960's and 1970's gave way to the Nuclear and Reactor Physics course, which later became simply Nuclear Physics. The last time we loaded the reactor was in 1991.

The NRC says the uranium must go

In a routine inspection in early 2000, the NRC discovered this inactivity for the preceding nine years and gave us an ultimatum based on NRC laws: either put the reactor into use or de-comission it - now! The faculty of the Department of Physics and Astronomy thought long and hard about this because we knew that once the uranium was removed from the VU campus, it was not coming back in our lifetime. We also knew that in the foreseeable future, it was highly unlikely that we would re-institute a strong reactor and fission-physics component in our curriculum given the status of the nuclear power industry in the U.S. We consulted Dr. Bretscher and other VU alumni as well as some other experts and it was the collective wisdom that if the DOE would take back the uranium we should move it now. If we were to have to pay a commercial vendor to dispose of the uranium the costs would be enormous. The decision was taken and by October 2000 all 1,425 uranium slugs were packed into 55 gallon drums, sealed, and shipped to a DOE site in Tennessee.

The end of an era

When the uranium left the campus we all knew that we were witnessing the end of an era. For 42 years, VU had a nuclear reactor and this was an item of distinction, not only for the Department, but for the University. In the 19.. issue of the U.S. News and World Report (USNWR) in which VU was rated first among its class of universities, it was a photograph of the reactor, along with students and Prof. Koetke, that was featured for the University. The editors of USNWR recognized that, for a small, high quality university, this uncommon laboratory facility was a significant mark of distinction which helped to set VU apart from others. The Department of Physics and Astronomy is proud of this history even as we are committed to maintaining a high quality laboratory instructional program in nuclear and particle physics. While the reactor is gone, the number and quality of the nuclear and particle physics experiments done in these laboratories has increased. (Have a look at the two laboratory courses: PHYS-345 and PHYS-430.)

Alumni replies

If you are an alumnus who worked on experiments with the reactor we would welcome hearing any interesting stories you have to tell about your experiences with it. And, if your career was significantly affected by the hands-on experience you received doing experiments with the reactor, share that as well.

[Editor's note: I arrived at VU in August 1977, only a few days after Prof. Armin Manning died of a sudden and massive heart attack. He and Prof. Manuel Bretscher were instrumental in setting up the reactor and nuclear physics laboratory on the VU campus. Dr. Bretscher left VU in the early 1960's to do research at Argonne National Laboratory where he has remained to the present. In recognition of Dr. Manning's long service to VU and especially to his pioneering efforts to establish a credible undergraduate nuclear and reactor physics program at VU, the new laboratories in the Neils Science Center were named the Manning Nuclear Physics Laboratory. (DDK)]


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