scram
Language: English
Part of speech: noun
Pronunciation: enpr: skrăm
ipa: /skɹæm/
rhymes: -æm
Forms: form: scrams
form: SCRAM
Etymology: Uncertain; the verb is possibly derived from etymology 1. It has been suggested that the word is an acronym for phrases like “safety control rod actuator mechanism”, “safety cut rope axe man”, “safety control rod axe man”, and “safety control rods activation mechanism”, but these are most likely backronyms.
The noun is probably derived from the verb.
Senses: examples: text: During scram operation, a scram signal de-energizes the inlet and outlet scram valves. The outlet scram valve vents the volume above the drive piston to a scram dump tank. The inlet scram valve supplies scram pressure obtained from an accumulator to the under side of the vented piston.
ref: 1960 October 5, John Roberts, S. F. Armour, “Introduction”, in T7 Tanker Locking Piston Control Rod Drive Scram Analysis (GEAP 3561), Oak Ridge, Tenn.: Office of Technical Information, United States Atomic Energy Commission, →OCLC, page 2:
text: Of the 14 scrams experienced, none was caused by operation exceeding the design parameters. Eight scrams occurred with the control rods withdrawn. [...] Six scrams occurred while the rods were inserted. Five were intentional to prevent accidental rod withdrawal, and one was the unintentional result of an instrument adjustment.
ref: 1966 fall, staff of First Atomic Ship Transport, Inc., “Operating Experience of the N.S. Savannah in Commercial Service”, in Nuclear Safety: A Quarterly Technical Progress Review, volume 8, number 1, [Oak Ridge, Tenn.]: Division of Technical Information, United States Atomic Energy Commission, →ISSN, →OCLC, section VI, page 65:
text: By the time scram is completed, coolant temperatures would likely be climbing due to the combination of a large heat capacity within the fuel pins and low coolant flow.
ref: 1981, Alan E. Waltar, Albert B. Reynolds, “Unprotected Transients”, in Fast Breeder Reactors (Pergamon International Library of Science, Technology, Engineering and Social Studies), New York, N.Y.; Oxford, Oxfordshire: Pergamon Press, →ISBN, section 15-5.D (Loss of Ultimate Heat Sink), page 604:
text: Although fission stops almost immediately with a SCRAM, fission products in the fuel continue to release decay heat, initially about 6.5% of full reactor power. [...] Corresponding with the SCRAM, emergency generators were automatically activated to power electronics and cooling systems.
ref: 2016, Nabil Abu el Ata, Rudolf Schmandt, “Understanding the Hidden Risk of Dynamic Complexity”, in The Tyranny of Uncertainty: A New Framework to Predict, Remediate and Monitor Risk, Berlin; Heidelberg: Springer, →DOI, →ISBN, part I (Once upon a Time), page 21:
text: Other indicators can be used to measure the performance of an NPP [nuclear power plant] including the number of scrams (emergency shutdowns of a nuclear reactor), the collective dose (a measure of the total amount of effective dose multiplied by the size of the exposed population), the amount of low-level waste generated, and the fuel reliability. The number of scrams dropped from the peak of 30 in 1984 to only one in 2004 and 2–3 in the last two years.
ref: 2011, Min Lee, “The Past, Present and Future of Nuclear Power in Taiwan”, in Xu Yi-chong, editor, Nuclear Energy Development in Asia: Problems and Prospects, Basingstoke, Hampshire: Palgrave Macmillan, →DOI, →ISBN, page 171:
topics: natural-sciences
physical-sciences
physics
glosses: A shutdown of a nuclear reactor (or, by extension, some other thing), often done rapidly due to an emergency.
examples: text: Each room housing a radiation source has a red-buttoned "scram" switch on the wall. One touch of the switch and all equipment stops abruptly.
ref: 1963 June, Kenneth Calkins, “Linac and Dynamitron”, in Boeing Magazine, volume XXXIII, number 6, Seattle, Wash.: Public Relations Division, Boeing Airplane Company, →OCLC, page 6, column 2:
text: She watched as the Marine technical team leader pressed the red SCRAM buttons for each reactor, setting off a chorus of alarms.
ref: 1993, Tom Clancy, Marine: A Guided Tour of a Marine Expeditionary Unit, New York, N.Y.: Berkley Books, published November 1996, →ISBN:
text: In particular, measures have been taken to make the scram system more fast-operating and to exclude any possibility of its being deliberately shut off by the personnel.
ref: 1998, Vladimir M. Munipov, “Ergonomics [Disregarding Ergonomic Design Principles: Chernobyl]”, in Jeanne Mager Stellman, editor, Encyclopaedia of Occupational Health and Safety, 4th edition, volume I, Geneva: International Labour Office, →ISBN, page 29-96:
text: Today it is considered to be true that the accident paradoxically was ultimately caused by the emergency shut down of the reactor. By sending in the practically completely withdrawn scram and control rods, the reactivity of the reactor by the faulty conception of the rods was for a short time not lowered, but augmented.
ref: 2004, Dieter Berg, “Radionuclides Released into the Environment”, in Richard Tykva, Dieter Berg, editors, Man-made and Natural Radioactivity in Environmental Pollution and Radiochronology (Environmental Pollution), Dordrecht: Springer Science+Business Media, →DOI, →ISBN, page 119:
topics: natural-sciences
physical-sciences
physics
glosses: The device used to shut down a nuclear reactor; also, the button or switch used to initiate a shutdown.
Derived terms: reactor scram