Designating a small nuclear reactor, built for research purposes, that develops so little power that no cooling and minimal shielding are required; = zero-poweradj.
1947
The ZEEP got its name from the initials of the words ‘zero energy experimental pile’.
Bulletin of Atomic Scientists November 327/2
1981
Fast neutron fluence measurements in the core of a zero-energy research reactor.
Nuclear Energyvol. 20 467
2014
For a zero energy or low energy reactor it should be designed from the outset so that it would be difficult to increase the neutron flux.
zero-energy typically occurs about 0.01 times per million words in modern written English.
zero-energy is in frequency band 3, which contains words occurring between 0.01 and 0.1 times per million words in modern written English. More about OED's frequency bands
Frequency data is computed programmatically, and should be regarded as an estimate.
Frequency of zero-energy, adj., 1940–2010
* Occurrences per million words in written English
Historical frequency series are derived from Google Books Ngrams (version 2), a data set based on the Google Books corpus of several million books printed in English between 1500 and 2010.
The overall frequency for a given word is calculated by summing frequencies for the main form of the word, any plural or inflected forms, and any major spelling variations.
For sets of homographs (distinct entries that share the same word-form, e.g. mole, n.¹, mole, n.², mole, n.³, etc.), we have estimated the frequency of each homograph entry as a fraction of the total Ngrams frequency for the word-form. This may result in inaccuracies.
Smoothing has been applied to series for lower-frequency words, using a moving-average algorithm. This reduces short-term fluctuations, which may be produced by variability in the content of the Google Books corpus.
Decade
Frequency per million words
1940
0.011
1950
0.012
1960
0.011
1970
0.012
1980
0.014
1990
0.014
2000
0.013
2010
0.013
Originally published as part of the entry for zero, n. & adj.