The Nucleus (formerly Mount Desert Island Naval Facility) is a pre-War United States Navy submarine base, and after DiMA made it his home, allowed the Church of the Children of Atom to settle the location. In return for the new home and center of worship, they agreed to protect his old memories from being accessed.
The Nucleus, or rather the Mount Desert Island Naval Facility, is a former United States Navy submarine pen, still housing the derelict USS Democracy in its dry dock. While there for repairs and refitting the submarine's reactor was sabotaged by the captain, Arnold Wabash. With the Democracy's nuclear reactor leaking radiation. Its crew and captain were recalled while hazmat teams worked around the clock to clean the facility and make the submersible usable again. However, the process would take weeks to complete. Admiral Edward Grath suspected foul play and informed Captain Wabash that he would file the court martial personally if he was responsible. The personnel of the base would survive the nuclear bombardment, and so would the admiral, but not the captain.
Following the Great War, the facility lay idle, its radiation keeping people away, until around 2178. After DiMA landed on the Island, he found the facility and made it his home. Some time later, Faraday would join DiMA, and later, after the Church of the Children of Atom was exiled from Far Harbor, the congregation of the Church of the Children of Atom lead by High Confessor Martin stumbled into the facility. Afterword DiMA would leave to found Acadia leaving the base in safe hands. While there however, DiMA used the base's computers to expand his limited storage capacity, offloading the oldest memories into the pen's data banks. For their new home, High Confessor Martin agreed to guard his memories.
The facility exterior, made almost entirely of concrete, is built into the side of a mountain.
Continuing forward through a wooden shack, there is a wooden ramp up. If one goes up, one will arrive at the shopfront of Sister Mai, and a little bit further is the shopfront of The Archemist. Turning left and going up the stairs leads to Brother Kane and a power armor station. Going further up the stairs will lead to the entrance to the Nucleus Command Center, guarded by a zealot.
Going straight from The Archemist's shopfront, there is a staircase that goes up on the right and a staircase that goes down on the left. The staircase on the right goes through multiple wooden shacks to end up at the entrance to The Vessel. The staircase down leads to Zealot Ware. From Zealot Ware, there is another staircase on the right that leads to the bottom of The Vessel, and a ramp up. The ramp up also leads to the entrance to The Vessel.
- Brother Devin's diary - Sticking out from under the mattress In Brother Devin's shack in the southwest section on the top level.
- Footlocker key - Behind the left red bench in the storage room just before the decontamination arches. Opens a footlocker in The Vessel, available during Witch Hunt.
- Taste test - To the right of Brother Kane.
- Repairs in progress - Near the decontamination arches to the east.
- Put It from Your Mind - On a chair in a shack nearest to the sub's periscope.
- High Confessor's note - Given to the player by High Confessor Tektus during Witch Hunt.
- Kiloton radium rifle - Sold by Brother Kane.
- Recon Marine right- and left arm - Purchased from Sister Mai / Brother Kane.
- Atom's Judgement - Received from Grand Zealot Richter upon completion of the quest The Heretic.
- Radical Conversion - Received from Sister Mai upon completion of the quest Ablutions.
- 2 fusion cores on the metal shelves in the first wooden shack upon entering.
- 2 cannonballs in a bucket up in the catwalks at the end of the first hallway to the west after exiting the end of the Nucleus Command Center, next to a huge pile of cans.
- High Confessor's robes and helmet - Worn by Tektus.
- Inquisitor's cowl - Reward from Tektus for completing the quest Witch Hunt.
- Atom's Bulwark - Reward for completing Reformation or Cleansing the Land.
- Robes of Atom's Devoted - Given by Grand Zealot Richter after completing Visions in the Fog.
- When visiting while wearing power armor, the children may comment about how Atom powers the suit.
- ↑ Far Harbor loading screen hints: "The Nucleus is home to the Children of Atom. It is built out of a prewar nuclear submarine base that the Children have converted into a town and center of worship."
- ↑ The Nucleus terminal entries; Captain Wabash's terminal, SUBJ: VR System
- ↑ The Nucleus terminal entries; Captain Wabash's terminal, SUBJ: Containment Leak
- ↑ The Nucleus terminal entries; Captain Wabash's terminal, SUBJ: Where are you
- ↑ Safe room security tape
- ↑ The Sole Survivor: "The Children of Atom on this island. You were helping them?"
DiMA: "Yes. I know their faith in radiation as a type of god is a bit... different, but who am I to judge? I was using a submarine base as a home when Martin and his followers stumbled inside. They had been cast out of Far Harbor for their beliefs. When I left to found Acadia, I knew the base would be in safe hands. They needed a home. A place to belong, just like I did. But now Martin is gone, and his successor, Tektus, wants to finally end the feud with Far Harbor, by letting the Fog swallow them."
- ↑ The Sole Survivor: "You left your memories behind? How does that work?"
DiMA: "As a prototype synth, my... raw data capacity is limited. I began using computer banks to expand. To give me room to ponder. See new things. "