The scientist spoke on condition of anonymity because of the sensitive nature of the issue.
A watchdog group now is raising questions about whether the replacement triggers, also known as pits, can be guaranteed to be as reliable as those already in some 400 W88 warheads. The original triggers were made with the benefit of underground nuclear testing, which the U.S. She posed that question in a letter last Friday to Energy Secretary Samuel Bodman.
The Project on Government Oversight says it was told by some Los Alamos scientists that the trigger certified last July and known as the W88 pit needed 72 waivers from the specifications used for the original triggers, including 53 engineering-related changes.
Precise manufacture of the trigger is essential.
The new ones were made by using a mold to cast the grapefruit-size plutonium sphere. The last of the original triggers were manufactured in the late 1980s.
“With this large number of waivers, how is it possible to objectively tell whether the pit will even work?” said Danielle Brian, executive director of the group that monitors nuclear weapons-related activities. Because the United States no longer conducts underground nuclear tests, the Los Alamos scientists had to rely on other sources to replicate the original triggers and guarantee that the replacements would be as reliable as the old. The original triggers, all made at the now-closed Rocky Flats facility in Colorado, were hammered into precise form. It meant the warheads, after testing that makes the original trigger unsuitable for reuse, could be reassembled with a new trigger and put back into service.
In a warhead’s detonation, a conventional explosive packaged around the pit compresses the plutonium inward, creating enough pressure for an atomic chain reaction. These means included small-scale plutonium tests, technical data from past underground tests, and computer codes and models.
Since last summer’s announcement, the Los Alamos lab has made 10 additional W88 triggers. So far, nine have earned the “diamond stamp” from the National Nuclear Security Administration, which oversees the lab’s programs. Such approval means they are ready to use.
Resting atop the Trident II missile, the W88 warhead is among the mainstays of the country’s submarine-based nuclear arsenal. This process is viewed by metallurgists as producing a stronger product.
Any variation or flaw in the pit could cause a warhead not to detonate properly or to detonate with less explosive power than expected.
The government acknowledges differences between the old triggers and their replacements.. For years, however, testing the warhead’s components to ensure the weapon produces the intended blast instead of a fizzle has been complicated by a lack of replacement plutonium triggers.
Last summer, the first replacement plutonium trigger in 18 years received “diamond stamp” approval signaling it was ready for use in a warhead. That, in turn, creates the high temperatures and pressure to ignite a “secondary” nuclear component. To scientists at Los Alamos National Laboratory in New Mexico, that was a milestone to celebrate. halted in 1992, and through a different process than the replacements. The result is a a massive hydrogen blast.
At least one other replacement pit required 71 specification waivers, a Los Alamos scientist indirectly involved in the production process told The Associated Press