Designating a small nuclear reactor, usually built for research purposes, that develops so little power that no cooling and minimal shielding are required; = zero-energyadj.
1950
Zero-power reactor, an experimental nuclear reactor operated at low neutron flux and at a power level so low that not only is no forced cooling required but also fission-product activity in the fuel is sufficiently low to allow the fuel to be handled after use without serious hazard.
Nucleonics September 104/2
1983
Plate versus pin geometry continues to be an issue for Zero-Power Plutonium Reactor (ZPPR) analysis.
zero-power typically occurs fewer than 0.01 times per million words in modern written English.
zero-power is in frequency band 2, which contains words occurring between 0.001 and 0.01 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-power, adj., 1950–2010
* 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
1950
0.011
1960
0.0094
1970
0.0083
1980
0.0076
1990
0.0059
2000
0.0046
2010
0.0037
Originally published as part of the entry for zero, n. & adj.