In Dong Tianyu's plan, the bottom layer was designated as the equipment layer and electronic device storage layer, for which he had specifically invested a large sum of money to install radiation-shielding lead sheets.
It's worth knowing that the entire room is covered in radiation shielding lead sheeting, a cost that would make even a billionaire like Dong Tianyu wince.
In reality, Dong Tianyu could have simply constructed a few independent radiation-proof rooms, which would not have cost as much.
However, given that electronic devices will become a rare commodity after the disaster, Dong Tianyu ultimately decided to increase investment for the sake of future living standards.
Ultimately, aside from leaving few movement areas, the rest of the bottom level of the cave was covered with thick lead sheets.
The absence of a complete lead sheet covering was not due to inability, but a necessity - specific gaps must be left open.
The interchange location of the ground source heat pump connected to the underground pipeline.
The ventilation pipeline connecting the fresh air equipment to other areas.
The conduits for the elevator platform.
These three locations could not be completely sealed off, but when it came to design, these connection points were retrofitted.
If necessary, the connection between the ground source heat pump and the fresh air pipeline could be disconnected at any time, and lead sheets could be added to the base of the elevator platform. If need be, the elevator could just be halted at the upper floor.
With respect to electromagnetic protection, Dong Tianyu has done everything possible to achieve the best level currently attainable.
In terms of cold protection, ground source heat pumps theoretically offer the best cost-effectiveness.
The ground source heat pump is a type of high efficiency, energy-saving and eco-friendly heat and cooling system that utilizes shallow geothermal energy. By inputting a small amount of high-quality energy (electrical energy), this pump can transfer energy from a low-temperature heat source to a high-temperature one.
In winter, heat from soil is "extracted", and after being raised in temperature it is supplied indoors for heating; in summer, heat from indoors is "extracted" and released into soil, which can maintain the uniform temperature of the ground at a balance all year round.
Simply put, the principle is similar to an air conditioner, but while an air conditioner works by pumping Freon into the pipes and operating outdoors, a ground source heat pump works by filling the pipeline with water and operating underground.
Despite having a ground source heat pump, this device is only useful in the early stage; its heating effect becomes worse in the later stages.
After all, the outdoor temperature will reach as low as negative 100 degrees Celsius, at which point the temperature of the shallow earth layer will not be able to perform the function of insulation. So, Dong Tianyu also made reserves of newly produced traditional fuel.
This newly produced traditional fuel is essentially a special type of coal. This specially processed coal releases heat ten to fifteen times more than ordinary coal, but its price is several tens of times higher than ordinary coal.
From a cost-effectiveness perspective, the practicality of this coal is not high, but during the depths of winter, this coal is a lifesaver that money can't buy.
Once the electromagnetic protection and cold insulation were settled, the next most important issue was oxygen within the refuge center.
Fortunately, the technology for oxygen production using algae is mature now, and it's quite simple to purchase both the algae and the nutrient solution necessary for preserving the algae.
Airing the four floors is even more simple and doesn't require a special factory for customization. Large fans and iron pipes are cheap, efficient, and easy to repair and replace.
Compared to the air vents in the fallout shelters of his former life, this interior air circulation system is infinitely more efficient.
Once the infrastructure is sorted out, the next issue is storage of resources.
Dong Tianyu first acquired a supermarket business license, setting the business address in the village.
Don't think this is a waste of time. In fact, many commonly used items at home don't raise eyebrows when purchased in small amounts, but as soon as they become bulk purchases, without a proper justifiable reason, you could definitely get hauled into a black room for an audit.
Take, for instance, commonly used items like salt and sugar. It's no issue to buy a few pounds, a dozen pounds, or even hundreds of pounds at a time. But once the transaction volume reaches upwards of a ton, without a proper reason, there will surely be someone inviting you in for a chat.
In terms of resources, aside from direct purchases of various condiments such as salt and sugar, Dong Tianyu also ordered grain liquor, canned food, and various kinds of dried vegetables from small workshops.
It's not that these items aren't available for direct purchase, but doing so would not only be expensive, but also wouldn't reach the storage life Dong Tianyu desired.
Take the most common alcohol for example, the alcohol said to be cellar-stored for three to five decades that you buy on the market is actually blended alcohol. The alcohol that has truly been cellar-stored for three to five decades is pure alcohol.
This is why a lot of alcohol purchased and stored for more than a decade turns sour.
As for canned goods, they need not be mentioned. The main reason canned goods gained the reputation they did in the 50s and 60s, other than the fact that fruit was a luxury back then, was the syrup in the cans. After all, it was difficult for ordinary people to get their hands on sugar.
As he had plenty of time, Dong Tianyu was well-prepared this time, and he air-dried large volumes of grains and vegetables before sealing them in vacuum packaging, significantly increasing the shelf life of the food.
Not only that, but Dong Tianyu also hired people to make long-lasting wind-dried foods such as sausages, dry-cured meat, and ham, leveraging the cool conditions inside the cave.
After the food was stored, adequate preparations were made for water supply.
It goes without saying that tons of bottled water and beverage syrup were purchased, and a large quantity of pure grain alcohol was also custom made. Along with the speciality grape wine from Shaw County near Pengcheng, beverages were adequately supplied.
Adding to that the groundwater wells resulting from drilling for geothermal wells, combined with filters, not only was there plenty of water for daily life, but it could also serve as drinking water if necessary.
So it was that Dong Tianyu spent the majority of his savings on various preparations before doomsday came.
However, Dong Tianyu's life didn't change all that much. He went to work as usual, and although the refuge center was just outside the third ring road of Pengcheng, his family and friends were only aware that Dong Tianyu had become busier, and didn't know much more.
As for the village at the foot of the mountain, although big trucks often passed through the village and traveled up the mountain, everyone simply assumed that the mountain was still under construction. Although they were initially curious, they eventually got used to it and did not say much.
Dong Tianyu assumed things would keep on as before, and was even considering whether or not to make a bit of fast money when doomsday came.
Suddenly, the sound of machinery echoed in Dong Tianyu's ears.
"The first day of the disaster has arrived. The survival system is starting."
"3"
"2"
"1"
"The survival system has been activated. It is detected that the host's environment can be bound as a refuge. Do you want to bind it?"
"What's happening? A system has appeared? Bind!" With no other options, Dong Tianyu decisively chose to bind.
Intangible fluctuations emanated quickly from Dong Tianyu's body, spreading rapidly in all directions.
"Refuge Center binding has been successful, the survival system has been activated."
"Refuge Center rating: D. Basic technological refuge center, can provide 1-10 people with 5-15 years of survival."
"Refuge Center upgrade system has been activated!"
"Please choose a survival direction: Technology, Mysticism, Biology."
Looking at the three options before him, Dong Tianyu hesitated, undecided on which option was best.
However, he speculated that the three options provided by the system would not be bad, because with the system, the design was bound to be better than his original design.