Atomic-powered runway lights may guide bush pilots in Alaska
Radioluminescent lights are the nearest that modern science has come to the magic lantern: They burn for up to a decade without wires or an external power source.
Arctic bush pilots will be taking off and landing aided by their ghostly glow , flying into the village of Central, Alaska. The town lies 90 miles north of Fairbanks, has a winter population of 70, and during the long Arctic night, its only link with the outside world is by air.
These ''RL'' lights are part of a test being conducted by the US Department of Energy, several branches of the military, the Federal Aviation Administration , and Alaska's Department of Transportation. Its purpose is to determine whether the lights can help the pilots who knit the sprawling state together. If all goes well, the state's back country may become festooned with them.
''We became aware that the federal government was developing these lights for military purposes and felt they might help us as well,'' says Lee Leonard, chief of energy research for Alaska's transportation department.
RL lights have been around for 25 to 30 years. They have been used for some time in hospitals and other buildings where uninterrupted lighting is essential. They are also employed as backup exit lights in a number of airliners. Half a dozen small companies in the US and Europe manufacture them.
Despite their obvious virtue, these lights remain one of the least familiar byproducts of the atomic age. They look little more remarkable than ordinary fluorescent tubes, and are filled with tritium gas. The gas, a waste product of nuclear power plants, is a radioactive variety of hydrogen. As the tritium decays, the charged particles it gives off are absorbed by a phosphorescent coating on the inside of the glass tube, causing the coating to glow. But old designs were dim, shining with the intensity of no more than a 40-watt bulb. Only recently have they been made bright enough for applications such as runway lighting.
Air transportation is vital to Alaska, particularly in winter. But winter is also the most hazardous time to fly because of the decreasing hours of daylight. Thus, much of Alaska's flying is in darkness, and the state's aviation accident rate is about twice the national average.
Despite this, most landing fields are little more than flat, open spaces. When a bush pilot wants to land at a remote strip in darkness, he buzzes the field and then circles until the villagers drive enough vehicles to the runway to illuminate it with headlights. The cost of conventional lighting is prohibitive, says Mr. Leonard, so the radioluminescent light tests being watched with interest.
To equip a remote Arctic runway with these unconventional lights could cost from one-fifth to one-half the price of installing conventional lights. The fact that they don't require any maintenance beyond regular cleaning and need no electrical power - an expensive commodity in rural Alaska - means further potential savings.
Although anything labeled radioactive would be controversial in the ''lower 48,'' so far the tritium lights have generated little, if any opposition in Alaska. ''There is so little radioactive gas in one of these lights that a person standing next to one when it broke would receive a negligible dose of radiation,'' says George A. Jensen, a senior research engineer at Battelle's Pacific Northwest Laboratory, who is managing the test.