| EWS | early warning system |
| EEI | Edison Electric Institute |
| EFPD | effective full power days |
| EFPH | effective full power hours |
| EFPY | effective full power year |
| EMF | effective multiplication factor |
| eff | efficiency |
| EPRI | Electric Power Research Institute |
| EDM | electrode discharge machining |
| EH | electrohydraulic |
| EMI | electromagnetic interference |
| emp | electromagnetic pulse |
| emu | electromagnetic units |
| emf | electromotive force |
| e | electron |
| e.u. | electron units |
| eV | electron volt |
| EDMS | electronic document management system |
| electrosleeving |
| esu | electrostatic units |
| el | elevation |
| EARS | emergency assessment and response system |
| ECCS | emergency core cooling system |
| EDG | emergency diesel generator |
| ENS | emergency notification system |
| EOP | emergency operating procedure |
| EOC | Emergency Operations Center |
| EOF | Emergency Operations Facility |
| EPZ | emergency planning zone |
| EPS | emergency power system |
| ERF | Emergency Response Facility |
| ERFDS | Emergency Response Facility Data System |
| ERMC | Emergency Response Media Center |
| ERP | Emergency Response Plan |
| ES (also OES) | Emergency Services, California Office of |
| EOC | end of cycle |
| EOL | end of life |
| endpoint |
| EIC | Energy Information Center |
| ERDA | Energy Research and Development Administration |
| ESF | engineered safety feature |
| ESFAS | engineered safety features actuation system |
| EAC | engineering advisory committee |
| ECN | engineering change notice |
| ECO | engineering change order |
| ES | Engineering Services |
| EWR | engineering work request |
| EIS | Environmental Impact Statement |
| EPA | Environmental Protection Agency (U.S. government) |
| EPP | Environmental Protection Plan |
| EQ | environmental qualification |
| ER | Environmental Report |
| ECG | equipment control guidelines |
| EFPY | equivalent full power years |
| est | estimate |
| (and others) | et al |
| etc. | et cetera (and so forth) |
| et seq. | et sequentes (and the following) |
| EIT | Event Investigation Team |
| ERT | Event Response Team |
| EAB | exclusion area boundary |
| EDO | Executive Director for Operations (NRC) |
| e.g. | exempli gratia (for example) |
| exp | exponent, exponential |