Siheyuan (traditional courtyard house): Starting with the Korean War, returning home to take charge

When the Jeep stopped in front of the Luoyang Refractory Materials Research Institute, He Yuzhu sensed something was wrong.

It wasn't the heat. It was the acrid smell emanating from the workshop, like steam rushing out the moment you lift the lid of a steamer, making your throat tighten. He pushed open the car door, his feet touching the ground, the soles of his shoes burning hot. In Luoyang in June, the sun is scorching, but this wasn't from the sun itself.

Dean Liu was waiting at the workshop entrance. His white coat was open at the collar, revealing an old undershirt underneath, and sweat kept dripping from his forehead. When he saw He Yuzhu, he didn't say anything, but stepped aside to let him through the doorway and pointed inside.

He Yuzhu went inside. The workshop wasn't big, but it was hot. The heat wasn't dry, it was stifling, like being crammed into a kitchen with no windows and the stove still burning. He walked to the observation window and looked inside through the thick glass.

A black tile lay in the furnace. It was about a foot square, with a smooth surface. A dark red light shone from beneath it, like the color of dying embers. The tile didn't move, but He Yuzhu felt it was breathing.

"How long has it been burning?" He didn't turn around.

Dean Liu handed over the thermometer, his hand trembling slightly. It wasn't nervousness, but exhaustion. He had dark circles under his eyes, his lips were dry and chapped, and his voice sounded like sandpaper grinding against iron when he spoke.

"Four hours. 3200 degrees Celsius, plus or minus five degrees. I didn't dare leave for a moment."

He Yuzhu took the thermometer, glanced at it, and said nothing. He returned the thermometer, bent down, and brought his face close to the glass. The surface of the tile was smooth, without cracks or bubbles, and even the color was uniform. He stared at it for more than ten seconds, then straightened up.

"Where's the plasma? Has it passed through?"

Dean Liu walked to another piece of equipment and pulled open the shutter of the observation window. Inside was a plasma generator, its nozzle aimed at a tile of the same size. Blue electric arcs jumped between the nozzle and the tile, hissing and crackling like countless tiny snakes crawling.

"The power was increased to 120% of the design value, 3,500, and it was charged for two hours." He paused, "It was taken down for inspection, and there was no ablation on the surface, no cracks, and no change in the microstructure."

He Yuzhu squatted down and looked at the tile through the glass. Blue arcs of electricity danced on its surface, but the tile remained motionless. He stood up and turned around.

"Take it down."

Dean Liu turned off the equipment and waited a few minutes. The furnace door opened, and a wave of heat rushed out. He leaned back slightly, steadied himself, and used long tongs to remove the tile, placing it on the table. The tile was still black, smooth, and hot to the touch.

He Yuzhu pulled a magnifying glass from his pocket and examined it closely. There were no burn marks or cracks on the surface. He tapped it with his knuckles; it made a crisp sound.

"Mass production. How many tokamak wafers are needed?"

Dean Liu opened his notebook. "Twelve thousand pieces." He looked up, his lips moved, then he lowered them again. "The cost of one piece, with current technology, is roughly equivalent to that of a car."

He Yuzhu pressed his hand on the table without saying anything.

Someone walked up behind him. The footsteps were heavy, thumping on the ground. Ma Yuejin squeezed to the table, reached out and touched the tile, then withdrew his hand as soon as his fingers touched it. He stared at the tile for several seconds, then reached out and touched it again, this time without pulling his hand back.

"Dean, twelve thousand pieces, twelve thousand cars." His voice wasn't loud, but each word seemed to be squeezed out from between his teeth. "How many cars can we produce in a year? Where would we get that much money?"

He Yuzhu did not answer.

Ma Yuejin took a step forward, his voice rising. "The satellite isn't even finished, the nuclear fusion hasn't even been ignited, and we're already throwing so much money at this? What if it fails? Who's going to take responsibility for all that money wasted?"

The workshop fell silent. Dean Liu stood to the side, the thermometer hanging limply in his hand, unsure where to put it. The technician, squatting in front of the control cabinet, froze, his hand still on the knob, not daring to turn around.

He Yuzhu stared at Ma Yuejin for several seconds.

Then he turned around, walked to the tile, and touched it. It was hot, but he didn't pull his hand back. He slowly ran his fingers across the surface of the tile, from one end to the other.

"If we fail, we'll lose money." He withdrew his hand and turned away. "If we succeed, we'll save our lives."

Ma Yuejin opened his mouth, but no words came out.

He Yuzhu looked at Dean Liu. "I'll figure out the money. You just focus on production. Quality must be guaranteed; every single piece must be tested, and any that doesn't meet the standards absolutely cannot be used."

Dean Liu nodded. "Okay. I'll arrange for three shifts, so the machines won't stop even when people rest."

He Yuzhu stayed in Luoyang for two days.

He visited the raw material workshop. White powder dripped from the hopper, and after being stirred, shaped, and sintered, it turned into black tiles. He then visited the testing workshop. A technician placed a tile into a scanning electron microscope, and the screen displayed its microstructure: densely packed fibers, neatly arranged, like bundles of steel bars.

Researcher Wang pointed at the screen, his words flowing rapidly. "The fiber reinforcement prevents cracks from spreading too quickly and causing them to split open immediately. It has ten times the flexural strength and twenty times the fracture toughness of ordinary ceramics."

He Yuzhu studied it for a long time. "When using it on a tokamak, safety comes first."

Researcher Wang closed his notebook and hesitated for a moment. "Where to extend it? There's still one problem. The way the tiles are installed. Traditionally, mechanical fixing is used, with screws and clips. But neutron irradiation will embrittle these metal parts, and over time they will loosen and fall off."

He Yuzhu thought for a moment. "Hot isostatic pressing (HIP) welding. We'll weld the tiles directly onto the copper alloy backing plate, without using screws."

Researcher Wang was taken aback. "Hot isostatic pressing? That requires large-scale equipment, which we don't have in China."

He Yuzhu said, "Imported. Bought from Sweden."

Researcher Wang nodded and didn't ask any more questions.

Back in Beijing, it was already dark. He Yuzhu sat in his office, took the list out of his drawer, flipped to the "Fusion" page, and added a line after "First Wall": "The Luoyang Institute and the Institute of Metal Research have jointly tackled a key problem; ceramic-based roof tiles are ready for mass production. One tile is worth a car; we've decided to replace them all."

Once you're done writing, put the list back and lock it.

The phone rang. He answered it; it was Chief Engineer Sun from Shanghai Electric on the other end. His voice wasn't loud, but he enunciated each word clearly, as if afraid someone would overhear.

"Hey, the main unit is installed. Vacuum chamber, coils, heating system, diagnostic system, everything is in place."

He paused.

"We're just waiting to ignite it."

He Yuzhu held the microphone but didn't speak. He stood up and walked to the window. It was pitch black outside; the moon was obscured by clouds, and nothing could be seen.

"Has the first wall been replaced?"

There was a few seconds of silence on the other end of the phone.

"Not yet. We're still using old roof tiles. The new ceramic ones are still being made in Luoyang."

He Yuzhu tapped his finger on the windowsill. Once, twice, three times.

"wait."

Chief Engineer Sun was taken aback. "When?"

"Wait until the new tiles are installed." He Yuzhu's voice wasn't loud, but every word was firm. "Safety first."

There was a few seconds of silence on the other end of the phone, then Chief Engineer Sun responded and hung up.

He Yuzhu stood by the window, looking at the night outside. A cool breeze seeped in through the cracks in the window. He stood there for a long time, then closed the window and drew the curtains.

Twelve thousand roof tiles, twelve thousand cars. Expensive. But human life is more precious.

He turned around, walked back to the table, and sat down. He took out the list again, turned to the "Fusion" page, and added a line after "First Wall": Shanghai Electric main unit assembly completed, awaiting the arrival of new tiles for ignition.