Ella Ames of the Free States may have discovered a way to create a protective drug that shields against radiation far better than Rad-X. As she did not complete her research, it's up to the dwellers to pick up the slack.
To create RadShield, Ames believed that the strangler pods had to be forced to bloom. However, forcing the plants to do so was a challenge. She figured that she could do so by dumping a special, high-powered fertilizer down at Dyer Chemical. Creating this chemical requires several special chemicals and irradiated bone meal.
The bone meal can be found in deathclaw nests in the Mire. Ella's research holotape contains a program that can be installed onto the PIP-Boy, which will set up a radiation signal tracker that will help locate the deathclaw nests in question, with a signal strength display in the objective list. The signal will fluctuate depending on distance: The closer the player gets, the stronger it will be. The bone meal will be inside the nest.
The chemicals required are scattered all over the Mire:
Potassium: Bed of the large blue truck on the south side of Dyer Chemical.
Phosphorous: Inside the small structure on the southwestern corner of Dyer chemical.
Nitrogen: Dyer Chemical, northern edge of the area, in the office on the second floor (inside the filing cabinets).
To mix the bone meal and the chemicals to make a fertilizer, players simply have to put them into the receptacle up on the facility's third floor, near the marked terminal, then select the option to flush the mixed fertilizer down the river.
Finally, players need to travel along the river and collect strangler blooms from the trees along the riverbank. The quest completes when they craft a RadShield at a chemistry station, available from the Healing category.