Science and Industry

NUCLEAR explosives give man the power to change the face of the earth instantly and drastically. Studies made for nuclear excavation of the sea-level canal across Central America dramatize this power. An expert has described the canal as the greatest civil engineering project ever undertaken by man. Yet the nuclear scientists believe that a channel 1000 feet wide and 250 feet deep can be blasted through the backbone of the Americas by exploding several hundred nuclear charges — in effect, controlled 11-bombs.

Basis for the experts’ optimism is Project Plowshare, the Atomic Energy Commission’s continuing study of nuclear explosives, which has provided a mass of data. A nuclear blast differs from a chemical explosion largely in the rapidity with which the energy is released. Set off underground, a nuclear explosive vaporizes, or melts, a huge cavity in the surrounding rock in a millionth of a second. This cavity grows upward as the shock wave breaks up the overlying rock, and the earth’s surface bulges into a huge dome, which explodes outward, throwing debris around the rim of a crater filled with broken rock.

Most of the radioactivity is locked in the melted rock far beneath the earth, but some escapes into the atmosphere. The trick is to use the right amount of explosive at the right depth to produce a hole of the desired size with a minimum release of radioactive material.

Of the three Isthmian canal routes now receiving major consideration, two — in Colombia and Panama — are sufficiently remote from population centers to permit the use of nuclear explosives. Either one would require between 40 and 50 miles of blasting. The charges — 250 to 300 would be needed — would be dropped into holes three to four and a half feet in diameter, varying in depth from 550 to over 2100 feet. Groups of four to fifty charges, sited along one to six miles of the route, would be exploded at one time.

The real test is cutting the spine of the Isthmus, the continental divide. A cut over 1300 feet deep would be made with one huge blast, using the equivalent of 35 million tons of dynamite. (The largest amount of conventional explosives ever set off in North America was about 1 300 tons, to remove an obstruction from a Canadian river.) Engineers are not certain that even the force of 35 million tons will be enough; it may be necessary to blast out only the upper portion of the cut and remove the broken rock from the bottom with earthmoving machines.

Dirt cheap

If all this sounds like an immensely difficult task, it is. What makes it even worth considering is the possibility of an enormous saving in cost. LTsed in large quantities, nuclear explosives are dirt cheap: thirty cents’ worth can do the job of a ton of conventional explosives and can move earth at one one-hundredth the cost of machine excavation. Nuclear explosives are also extremely compact; the equivalent of 100,000 tons of conventional high explosives weighs just five tons.

Economists estimate that assuming that toll charges are kept at the present level, there will be sufficient traffic by 1 9H0 to pay lor a new canal costing SI.25 billion. Route 17, through Panama, would cost $5.13 billion with conventional excavation; it is estimated that nuclear excavation would cut this to $650 million. Route 25, a longer canal through Colombia, would cost $5.26 billion with conventional methods, but would cost $1.2 billion with nuclear excavation. A third plan, converting the present Panama Canal to a sea-level route, for which nuclear excavation could not be used because of closeness to population centers, would cost more than $2.29 billion

Safety studies

It seems clear that nuclear excavation will have to be used if a new sea-level canal is to pay for itself without an increase in tolls. But the choice between nuclear explosives and conventional methods is still very much in doubt. Two major obstacles block any immediate use of nuclear blasting for a canal project: one technical, the other political.

The AEC itself is the first to point out that considerable research must be clone before a start can be made. More underground test blasts must be set of!' to learn what happens in different kinds of rock and at various depths. The nuclear devices themselves must be further improved to reduce radioactive contamination; the experts are hopeful of cutting the level to one percent of what it was just three years ago.

More safety studies must be made on the effect of ground shock, the structural response to blast, and the deposition pattern of radioactive debris, all vitally important in determining the size of the charges that can be used with safety and how large an area must be evacuated.

As part of this necessary research the AEC is considering an intermediate-size demonstration project called Carryall, in which 22 nuclear explosive charges would make a two-mile cut through the Bristol Mountains in California, about 200 miles east of Los Angeles. The cut would be used for an eight-lane interstate highway and would permit relocation of the main line of the Santa Fe Railroad.

For the canal project, research, demonstrations, and the manufacture of the explosive device could be carried out simultaneously and completed in five years — if the necessary 250 million dollars were available. Right now it isn’t. At: the level of the current AEC budget, this preliminary work alone would stretch out over a period of fifteen to twenty years.

Radioactive debris

An even greater obstacle is the limited test-ban treaty, ratified by the Senate in 1963. This forbids any nuclear explosion, even underground, if it distributes radioactive debris outside the country of origin. Despite the A EC’s advanced techniques for limiting radioactive matter to relatively small areas, the agency does not believe it possible to set off a series of blasts in Central America, where national boundaries are close together, without at least technical violation of the test-ban treaty.

Whether Russia and the other signatories to the treaty would permit an exception to be made would have to be the subject of some sticky political negotiations. Even if these were successful, there is no assurance that the Central American nations themselves would accept a series of nuclear explosions in their midst, despite the advantages of a new canal. All these countries contain groups eager to find any excuse to attack the United States, and few subjects pack the emotional content of nuclear explosions.

Dutch elm disease

Thirty-five years ago this summer, five dying elms in Ohio heralded the arrival of the Dutch elm disease on this side of the Atlantic. Since then, the disease has spread relentlessly through the range of the American elm, from New England to the Rockies.

’Ehis spring there is hope that the deadly Ceratocystis ul mi may be stopped before the elm vanishes entirely. A new attack has been found, not against the disease itself, but against the bark beetles that carry the infection from tree to tree. An insecticide called Bidrin can be circulated through a tree and practically guarantees that a beetle biting the elm bark will die before he can deposit the deadly fungus spores that he carries on his feet.

Shell Chemical developed Bidrin as an agricultural insecticide. Dr. Dale Norris, a University of Wisconsin scientist, found that Bidrin placed in holes drilled in elm trunks killed beetles on the trees, but that too much Bidrin injured the tree. Unlike sprayed insecticides, the chemical in the tree did not enter the food chain of birds and other animals. Eight years’ testing of dosage, injection methods, and timing culminated in a fifty-thousand-tree test in Milwaukee in 1964 and resulted in the first decline in diseased elms there in nine years.

Bidrin is injected into the tree from small plastic capsules, through a metal feeder tube that works like a hypodermic needle. The tubes are driven into the trunk at intervals of five to six inches around the circumlercnce. When a capsule is forced onto the tube, a seal breaks and the beetlecide, under pressure, squirts directly into the tree. The injector capsules and feeder tubes are then removed and buried. The beetlecide flows through the tree’s circulatory system, reaching the outermost branches and twigs, where 90 percent of the bark-beetle feeding occurs.

The Dutch elm fungus infeciion occurs for a period of about 20 days in spring, the exact period depending on weather, geographical location, and the individual tree. Bidrin remains toxic to the bark beetle for 30 days or more after its injection, and the treatment must of course be repeated each season. The cost varies, but a prominent tree service has estimated that “a few trees” might be treated “for $20 to $40.” However, Shell is not yet producing enough Bidrin to meet the demand.

Bidrin treatment is no do-it-yourself project. Dosage, timing, and handling requirements are too delicate for general use, and distribution is limited to professional personnel who have completed a Shell-supervised training program. Even though factory-sealed injection capsules minimize danger to the handler, Bidrin crews carry a supply of atropine (an antidote for nerve chemical poison) along with their heavy goggles, gloves, and coveralls. Once the chemical is in the tree, it is not dangerous.

Even treated trees will not be completely protected if they arc close to infected elms. The roots of neighboring elms sometimes grow together, and these connections must be cut to prevent infection. And of course Bidrin, since it affects only the beetles, cannot help an elm that is already infected.

For that, a treatment is needed that will make a direct attack on the disease itself. Scientists at G. D. Scarle and Company have developed an antifungal chemical, originally investigated for use against fungi that infect human beings, which inhibits growth of the disease fungus in seedlings; now they are trying to find a way to get the chemical to the infected part of a full-grown tree.

At Cornell, tree scientists are working on a really long-range project — trying to breed a diseaseresistant variety of elm. Our grandchildren may be the first to know whether they succeed.

Plastic dam

Engineers usually hope their dams will be as solid as Gibraltar, but a new 2000-foot structure planned for the Susquehanna River this year is deliberately designed to collapse, over and over again, do make this possible, the dam will be composed of seven neoprene balloons, shaped like enormous hot dogs, anchored to a concrete base in the river. Each year when flood danger has passed, the seven sections will be pumped up with air and water to a height of 8 or 9 feet, forming a 3000-acre lake for swimming and boating. When cold weather comes, the sections will be dropped to the bottom, clearing the way for spring torrents.

The dam segments have been built by Firestone out of synthetic rubber with a double nylon inner lining. Each section will have its own piping built into the foundation slab to which it is clamped so that it may be emptied independently.

The principle has been tried out successfully on small dams — notably a diversion dam on the Los Angeles River that can be collapsed in ten minutes when flood waters threaten. The wooden dam it replaced had to be repeatedly rebuilt.

Talking underwater

Skin divers can converse underwater with a new underwater communication system made by Bendix. The “Watercom” uses a specially designed transducer to transmit the voice up to 100 yards underwater; an old-iashioned, nonelectronic human ear is the only receiver needed. A special mouth mask connected to the breathing regulator allows the diver to move his lips freely, and his voice is picked up by a throat microphone.

The transmitter is housed in a 14-inch, 5-pound cylinder which is fastened to the diver’s air tank. The Watercom unit costs $239. A more expensive unit provides a hydrophone. When this is dropped off a boat in the water, it picks up sounds from beneath the surface and allows a two-way conversation between diver and boat.

Reconstituted beer

Young men who went to college in northern New England during Prohibition learned, among other things, an easy way to make hard liquor: take a jug of fermented cider, hang it out the window until a chunk of ice forms, pour off the highly alcoholic liquid that is left unfrozen, and drink it. The principle involved, of course, is that alcohol has a lower freezing temperature than water.

’l’his same principle is now being used, with more sophistication, in a new brewing technique that enables brewers to take most of the water out of beer, ship or store the concentrate, then put the water back when convenient, along with carbon dioxide for sparkle.

The reconstituted beer that results may have considerable impact on the traditionally conservative brewing industry. The brewer no longer pays for shipping the water in his beer kegs. And because the concentrate keeps far better than whole beer, it opens up the possibility of brewing in the off-season for sale in hot weather when demand skyrockets, something the brewers cannot do now because their beer would spoil before it was sold.

Traditionally, the local water used in beer is supposed to play a major part in the distinctive flavor of different brands of beer. The experts say this effect is retained in the concentrate and persists through reconstitution, whether tap or distilled water is added, unless the water has a strong flavor of its own, such as sulfur or chlorine.

The beer concentrators do not claim their product is better than fresh brewery-bottled beer, merely tliat even serious quaffers cannot tell the two apart. Bottled beer is never as fresh as beer that comes out of the vat, however, since it is lightand heat-sensitive, and some deterioration begins as soon as it is bottled. Beer concentrate, in contrast, can be held in storage without deterioration for as long as two years, according to tests made by Union Carbide.

Despite reassuring reports that the concentrate is likely to find its major outlet in overseas markets not now adequately provided with good beer, the smaller brewers in particular are less friendly to the idea than the big national companies. Because concentrate is much cheaper to ship long distances than whole beer, they fear they may be swampc.d by rival “bottling plants’5 in their own backyards, using concentrate from big breweries hundreds of miles away.

Instant-beer cartoons notwithstanding, the federal tax people have quashed any notion that beer concentrate might be sold at retail to be reconstituted at home. Putting the water back into beer, says the Internal Revenue Service, constitutes “brewing” and requires a brewer’s license.

Control of wildlife

Birth control for the coyote population of the United States presents none ol the usual sociological problems. With half a million coyotes on the prowl for sheep and chickens, mainly west of the Mississippi, and the number growing despite trapping, hunting, and poison, the Federal Bureau of Sport Fisheries and Wildlife has stepped in. Govern; ment scientists distribute food con: taming stilbcstrol, the synthetic female hormone, to coyotes during their breeding season to reduce the number of pregnancies (a typical litter is five or six pups, and a female starts bearing at the age of one year). The drug has no side effects on the animals who eat it, and it does not harm domestic pets if they accidentally eat the treated food.

Another example of chemical control of wildlife is Phillips Petroleum’s Avitrol, designed to control birds around airports and field crops by feeding them distasteful chemicals that apparently produce a reaction similar to the one that some children have to spinach. When the other birds hear the gagging and retching of the affected birds, they take off for distant points. The stuff can be mildly toxic to birds if amounts are not controlled, Phillips says, but it will not harm animals that eat the birds.