1. Radiation Safety External hazards & antagonistic threats
1st layout of the construction in 2012 and estimates for 2013 cost book were done according to the ESS “General Safety Objectives” [ESS ; based on valid legislation at that time]
Protection of the largest radioactive inventories against external hazards, such as seismic events, were assumed to be done via conventional civil engineering constructions and methodologies.
2014 construction permit was received together with special conditions which, regarding dose levels to the public in case of accidents were stricter, i.e. lower wrto to the ESS baseline document.
Note: ESS is classified as ‘special facility’, not as a nuclear facility

2. Radiation Safety External hazards & antagonistic threats
- In 2014, SSM (Swedish Radiation Safety Authority) announced that, in the aftermath of Fukushima, they were working on a completely new set of guidelines/rules for design of Buildings in Nuclear facilities. [in accordance with the updated EU regulations] - This document (‘DNB’) defines not only calculation methods, way of documenting and 3rd party review, but gave also new site specific seismic spectra (frequencies) that were to be considered.

3. Radiation Safety External hazards & antagonistic threats
The ‘DNB’ document was released in 2015:
Stricter requirements to be applied to the civil engineering design of the monolith and the active cell (especially the foundation)
As a consequence the overall design of the Target Building, the two adjacent instrument halls and the overlapping roof had to be updated/re-done.
That also required new competence, consultants and reviewers to be brought into the project.

4. Radiation Safety External hazards & antagonistic threats
End 2015 ESS received from SSM the revised special conditions for ‘physical protection’. Those conditions define, among others, in detail the antagonistic threats to be considered.
As a consequence new load cases for the hot cell were calculated and the design had to be updated