Images de page
PDF
ePub

of the Committee, made available in December 1989, urged strongly that the injector energy and the magnet aperture be increased.

The bypass idea was introduced to add a measure of flexibility in the experimental program of the Laboratory. In the 1986 conceptual design, all the experimental halls were placed along the collider ring, so that if any repairs or changes had to be made in a detector located in one of the halls the accelerator would have to be shut down. Bypasses provide a path for protons to travel around some of the experimental halls so that the accelerator can continue to run while work is being done on the detectors. We have recommended that the tunnels for the bypass be drilled (thus making most efficient use of the large tunnel boring machines while they are in place underground) but not outfitted in the initial configuration.

The recommended design was accompanied by a careful cost estimate, the first cost estimate prepared for a real SSC on an actual site. That cost estimate leads to a total project cost of between about $7.2 and $7.8 billion, depending on assumptions. The Laboratory staff is working closely with the DOE to develop a precise and agreed upon cost estimate that we intend to maintain as we build the supercollider. I want to be very clear about something here. Although this figure is higher than the $5.9 billion figure that had been associated with the 1986 conceptual design, it does not in any sense, constitute a cost Overtun. It is the first true cost estimate for the project as it is proposed to be built. We have examined, in detail, the reasons for the higher number. About half of the difference is due to the design changes mentioned earlier, design changes made necessary by the incorporation of technical information about the operations of accelerators that was not available at the time the conceptual design was prepared. The other half of the difference comes from revising the technical and economic assumptions that were used in the earlier estimate to provide a greater degree of realism. Thus, the current cost estimate incorporates what we feel are much more accurate labor rates and schedules than those that were part of the earlier estimate.

Understandable concerns have been raised about whether the new cost estimate presages further increases in the future. It does not. The cost estimate we have presented to the Department of Energy for its review is a conservative projection of the real costs of completing this project. High energy physicists, it must be noted, have had a good record in the past in completing projects on time and within budget. This was certainly the case at Fermilab, this nation's largest and most ambitious accelerator project. It is my intention, and that of the rest of the SSC staff, to maintain the good record of the past.

Perform geotechnical investigations and specify footprint

The Texas site provides an excellent geological base for the SSC, but because the collider tunnel will be situated below the ground it is imperative that the designers and constructors understand the geology in great detail. To that end, the SSC Laboratory has been carrying out a program of geotechnical investigation since last spring. That program has given us a much more accurate picture of the underground structure at the site and that, in turn, has enabled us to determine the optimum placement of the collider ring, the so-called footprint.

Once the footprint was specified, the state of Texas was able to identify with great accuracy the land parcels that would have to be acquired and provided to the Department of Energy. The state of Texas is currently beginning the land acquisition process.

Support preparation of the environmental impact statement

Before any construction work can begin at the SSC site, a Supplemental Environmental Impact Statement must be completed. The SEIS provides a detailed, site-specific update to the final environmental impact statement that was completed by the Department of Energy late in 1988. The Department has assigned the task of preparing the SEIS to Argonne National Laboratory, though the SSC Laboratory is providing much of the needed information to the Argonne team. DOE's current plans call for a completion of the environmental impact statement process by some time this fall.

While it would be inappropriate to prejudge the outcome of the environmental impact statement process until it is completed, my impression is that the data gathering to date has not discovered any environmental problems of serious import. This is not so surprising; one of the attributes of the Texas site that was noted during the site selection process was the apparent absence of any significant negative environmental impacts.

Select an architect-engineer/construction manager

The construction of the conventional facilities at the SSC -- the tunnels, shafts, and aboveground structures and site improvements -- will be a major and complex enterprise. To carry out the detailed engineering design work and to manage the construction project, the Laboratory will rely on a contractor with experience in large construction projects with significant underground components. A careful selection process has led to the selection of the team of Parsons Brinckerhoff of New York and Morrison Knudsen of Boise, Idaho, in association with CRSS, Inc. of Houston, Texas to serve as the architectengineer/construction manager for the SSC. We are just now entering contract negotiations with the PB/MK/CRSS team and hope to have a contract in place by late spring or early

summer.

It is worth noting that although the PB/MK/CRSS team will serve as construction manager for the project, the actual construction will be done by other firms that will be selected and managed by the construction manager. We feel that the involvement of broad and experienced industrial design and construction firms strengthens the project considerably.

Continue development of magnets

It has been recognized for some time now that a principal technical challenge facing the SSC -- perhaps the principal challenge -- is the design and production of the large superconducting dipole magnets that will guide the beams of protons around the ring.

The challenge is one of scale, not of concept. Superconducting magnets have been built and used in accelerators around the world. But none have been of the size and strength needed at the SSC. Under the auspices of the Central Design Group at Berkeley, a magnet research and development program was begun a few years ago to turn the proven concept of superconducting magnets into a design for the SSC dipole magnet. A number of mechanical and electromagnetic designs were developed and tested by the Central Design Group, working closely with scientists and engineers at Fermilab and Brookhaven National Laboratory. The magnet R & D program was incorporated into the SSC Laboratory last year and the development and testing program continued. As one of my first acts as director of the Laboratory, I established an advisory committee to give me its frank and constructive criticism of the magnet program. That committee reported to me in June of last year, endorsing the basic approach of our R&D program and indicating a number of areas where we could make technical improvements to the magnet design. The Laboratory has implemented the committee's recommendations.

To date, 14 full-length collider dipole magnets have been built and tested at the national laboratories. We now know that we can build magnets that achieve the required field strength at a temperature of 4.35K. One important characteristic of the magnets, their quench performance (the way they behave when they go from superconducting to normal), has been demonstrated to be satisfactory. Mechanical and cryogenic performance meets requirements.

Over the life of the magnet R & D program, the design of the magnets has evolved as new and improved ideas about mechanical and electromagnetic performance have been incorporated in the design. The result, by mid-summer of last year, was a "baseline" design. However, as I mentioned earlier, one change in the baseline design was recommended by accelerator experts and adopted late last year, that was the change in the inner coil diameter from 4 cm. to 5 cm. The change, reflecting an improved understanding of field quality in the magnets and the behavior of protons in the field, was a sensible and conservative one, one whose goal is to create a more reliable accelerator. I have established a task force at the SSC Laboratory to incorporate the modification in magnet aperture in the baseline design. The task force is progressing well; the new magnet cross section has been established and magnetic and mechanical design for the 5 cm, magnet is complete.

With the demonstration, in the testing program, of satisfactory field strength and mechanical performance, the emphasis in the SSC dipole magnet development program now shifts to two areas: field quality and manufacturability. These will be the focus, if you will, of the next year's program.

The involvement of the national laboratories in the magnet program has been strong and will continue in the coming year. At Brookhaven at present six long magnets are in various stages of assembly and test as are a number of shorter magnets. Brookhaven is also working on instrumentation for cold measurements of the magnets. Four long magnets are in assembly and test at Fermilab, together with a number of short magnets. We expect that Fermilab will be a focus for the effort to incorporate the aperture change in the baseline design. Lawrence Berkeley Laboratory is working on development of the quadrupole (focussing) magnet design and tooling as well as on a superconducting cable test facility.

A large number of superconducting magnets will be required for the SSC. The design calls for 8076 collider dipole magnets, 1699 collider quadrupole magnets, 858 special collider dipole magnets, 127 special collider quadrupole magnets, 929 dipole magnets for the high energy booster, and 561 quadrupole magnets for the high energy booster. For all but the special collider quadrupole magnets, we will turn to industry for assistance in design and production.

Within weeks, we hope to release a request for proposal seeking an industrial contractor to work closely with the Laboratory in the development of the final collider dipole design. While the SSC Laboratory and the other national laboratories possess substantial technical expertise and experience in magnet design and assembly, the industrial contractor will contribute capabilities in manufacturability, tooling, and high-rate production. At first, the industrial contractor will work closely with us and with Fermilab to design and assemble prototype magnets as well as the tooling necessary to permit mass production of the dipole magnets. At its own installation, the industrial contractor will prepare a small number of prototype and preproduction magnets after which we expect to begin production of the more than 8000 magnets needed to outfit the collider ring.

As soon as possible, and certainly before the end of 1992, we plan to conduct string tests of the magnets and associated accelerator systems both above ground and in a small section of tunnel constructed at the Ellis County site. In addition to giving us confidence that the magnet development and industrialization programs are proceeding on course, we expect to learn a great deal from these tests about installation procedures and about the geotechnical environment in which the collider tunnel will be located.

Initiate scientific programs

It is an interesting aspect of the experimental program at the SSC that it takes about as long to plan, design, and build the large detectors that will be used to examine the proton-proton collisions at the accelerator as it does to plan, design, and build the accelerator itself. The large detectors are enormous and complex enterprises in and of themselves; a completed detector may weigh more than 40,000 tons and cost several hundred million dollars. Typically, large international teams of scientists and engineers collaborate in experimental detector projects at major accelerator laboratories and we expect the same to be the case at

« PrécédentContinuer »