Category Archives: Modern Power Station Practice

Handling restrictions and criticality assessments

Decay heating In practice, the timing of the various irradiated fuel movements and related handling op­erations is rigidly controlled by post-discharge heating considerations. During their residence in the reac­tor, AGR fuel stringers generate powers ranging from about 6.5 MW to typically 4 MW at end of life. These are figures which should be compared with peak mag — nox channel […]

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Reactivity faults

Reactivity faults occur if there is an uncontrolled in­crease in the reactivity of the reactor either over the entire core, or locally. Such an increase inevitably gives power and hence temperature transients which must be limited by the protective equipment to less than the melting point of magnox. Indeed, because the strength of magnox decreases substantially at a few degrees […]

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Transport of fuel and radioactive materials including wastes

A wide variety of radioactive materials are transported from nuclear power stations. The main types are samples sent for analysis, radioactive wastes sent for disposal, items of contaminated/irradiated plant re­quiring off-site testing or maintenance. In addition, radioactive sources that are used at both nuclear and conventional stations for measurement and test pur­poses such as radiography and tracer experiments.

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Nuclear Safety Committee

The site licence for each station requires the CEGB to set up a senior committee to consider any proposal of major safety significance affecting the operating of the station. This committee is known as the Nu­clear Safety Committee (NSC). Even without the li­cence requirement, there would be a need for such a committee to provide authoritative advice to the station […]

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Department of Energy

The Department of Energy would be the lead depart­ment for all civil nuclear emergencies in England and Wales and would be responsible for the nuclear emer­gency briefing room in London. The briefing room would not be an operations room but would be the focal point in Whitehall for the information and brief­ing of government ministers and departments on the emergency. […]

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New fuel

The magnox fuel element is essentially a cylindrical bar of natural uranium encased in a magnesium al­loy can. Both the uranium and the can material have additional trace elements to provide the required met­allurgical properties. The bar is about 25 mm diameter by 750 mm in length (the Berkeley and Hunterston elements are about half this length) and a weight […]

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Manipulators

Many types of manipulators have been developed by the CEGB and there has been increasing use made of computers for control and display purposes. The ‘snake’ is a_multi-link manipulator in which the in­dividual units are motorised to enable the whole to be manoeuvred through a tortuous route. Computer control is employed to guide each link through the same path as […]

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Main provisions

Four primarv types of package (i. e., container or pack­aging, together with contents) are defined: Excepted, Industrial, Type A and Type u. In a graded approach the design requirements and, where appropriate, stand­ard tests and performance criteria are specified. They become more stringent as the hazard represented by the contents increases. Thus there are no specific per­formance standards for the […]

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The Lungs

The lungs are important as inhalation represents one of the easiest ways for radioactive material to enter the body. The purpose of the lungs is to provide an efficient system for exchanging carbon dioxide for oxygen in the red cells of the bloodstream. This takes place in the deep lung through the walls of alveoli which are tiny cavities formed […]

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