"Well, couldn't we drive boron rods into the mass and slow down the reaction?" asked Tom.
"No, Tom," answered Astro, "the control for the rods are inside the tube control box. We can't reach it."
There was a sudden loud ticking from the Geiger counter.
"Astro!" cried Roger. "The mass is building!"
"Here, lemme see!" shouted Astro. He took the instrument in his big hand and watched the clocklike face intently.
" ... fourteen hundred thirty—fourteen hundred fifty—fourteen hundred seventy—" He faced his unit-mates. "Well, that does it. The mass is maintaining a steady reaction without the energizing pumps. It's sustaining itself!"
"But how is that possible?" asked Tom.
"It's one of those freaks, Tom. It's been known to happen before. The fuel is just hot enough to sustain a steady reaction because of its high intensity. Once that baffle worked loose, the mass started wildcatting itself."
"And if it doesn't stop?" asked Roger tensely.
"It'll reach a point where the reaction comes so fast it'll explode!"