Nuclear Energy Ordinance
(NEO)

¹ Pre­vent­ive and pro­tect­ive meas­ures must be taken to avoid ac­ci­dents in nuc­le­ar in­stall­a­tions that may ori­gin­ate either with­in (in­tern­al) or out­side (ex­tern­al) the in­stall­a­tion.

² In­tern­al ini­ti­at­ing events in­clude re­act­iv­ity dis­turb­ance, loss of coolant, loss of heat sink, fire, flood­ing, mech­an­ic­al dam­age due to com­pon­ent fail­ure, dam­age to clad­ding when hand­ling fuel ele­ments, fail­ure of op­er­at­ing sys­tems, un­in­ten­tion­al ac­tiv­a­tion or faulty func­tion­ing of safety sys­tems, and mis­takes made by per­son­nel.

³ Ex­tern­al ini­ti­at­ing events in­clude earth­quake, flood­ing, ac­ci­dent­al crash of civil or mil­it­ary air­craft, squall, light­ning strike, shock wave, fire, loss of off-site power, impair­ment or loss of ex­tern­al cool­ing wa­ter sup­ply.

⁴ For the design of a nuc­le­ar in­stall­a­tion in ac­cord­ance with Art­icle 7 let­ter c, ac­ci­dents with­in the mean­ing of para­graph 2 and ac­ci­dents not triggered by nat­ur­al events with­in the mean­ing of para­graph 3 must be clas­si­fied by the fre­quency spe­cified in Art­icle 123 para­graph 2 RPO⁶. In ad­di­tion to the ini­ti­at­ing event, an un­re­lated single fail­ure must also be as­sumed. Proof must be provided that the re­quire­ments re­lat­ing to max­im­um ra­di­ation doses in ac­cord­ance with Art­icle 123 para­graph 2 RPO are met.⁷

^4bis For the design of a nuc­le­ar in­stall­a­tion in ac­cord­ance with Art­icle 7 let­ter c, in the case of ac­ci­dents triggered by nat­ur­al events in ac­cord­ance with para­graph 3, the as­sump­tion shall be made of a nat­ur­al event with a fre­quency of 10^‑3 per year and a nat­ur­al event with a fre­quency of 10^‑4 per year. In ad­di­tion to a nat­ur­al event trig­ger­ing the ac­ci­dent, a sep­ar­ate in­di­vidu­al er­ror shall be as­sumed. It must be demon­strated that the dose res­ult­ing from a single such event for mem­bers of the pub­lic:

a.

is no great­er than 1 mSv in the case of a fre­quency of 10^-3 per year;

b.

is no great­er than 100 mSv in the case of a fre­quency of 10^-4 per year.⁸

⁵ Proof must be provided by prob­ab­il­ist­ic ana­lys­is that there is ad­equate pro­tec­tion against bey­ond-design-basis ac­ci­dents. For this pur­pose, the pre­vent­ive and mit­ig­at­ing meas­ures in ac­cord­ance with Art­icle 7 let­ter d may be taken in­to ac­count.⁹

⁶The Fed­er­al De­part­ment of the En­vir­on­ment, Trans­port, En­ergy and Com­mu­nic­a­tions (the De­part­ment) shall define the haz­ard as­sump­tions and as­so­ci­ated eval­u­ation cri­ter­ia in an or­din­ance.