IEC 62598-2011 pdf free download – Nuclear instrumentation – Constructional requirements and classification of radiometric gauges.
5 General requirements
5.1 Measuring gap
In order to prevent persons placing their hands or any other part of their body in the usefulbeam, the gauges shall be constructed in such a way that the measuring gap is kept to apractical minimum.This also includes any other points where access to the useful beam islikely to occur. Where there is potential to expose body parts the user shall install additionalprotective devices.
5.2source holder
The source holder shall be designed and constructed in such a way that:
a) an easy installation and de-installation of the radioactive source is feasible underradiologically safe conditions;
b) a reliable positioning of the source is feasible under radiologically safe conditions.5.3Source housing
The source housing shall be designed and constructed in such a way that:
a) the radioactive source is protected under normal operating conditions against impactswhich could damage it if no other means are provided in the gauge for such protection;b) dismantling of the radioactive source by non-authorized persons is prevented (e.g. by
providing a safety lock，special tools which are necessary to open the housing,or bysecurity sealing procedures);
c)it withstands the adverse physical and chemical influences expected in accordance with
the user’s information (e.g., by means of installing an additional protective hood or anyother installation-related measures);
d) the radioactive source is secured in a manner to prevent the radioactive source fromfalling out even in the event of mechanical damage to the housing or in case of fire;
e) it is possible to carry out source leakage tests under radiologically safe conditions.5.4Alignment of the useful beam
The source and detector heads shall be aligned so that the collimating properties of CategoryA gauges restrict the useful beam so that it does not extend beyond the detector or its shieldswith no measured material in the measuring gap,provided this is necessary to conform topermissible limit values in accordance with 6.1. For Category B and C gauges,the standalone source housing or the source housing should reduce the dose equivalent rate outsidethe useful beam to levels as low as practical.
5.5other requirements
ln addition to the specified constructional requirements，the gauges shall comply with theprovisions as laid down in the respective valid version of the appropriate national regulationscurrently in force.
Additional non-safety relevant information on instruments and systems for which this standardis applicable is given in lEC 60692, IEC 60982 and IEC 61336. General constructionalrequirements forelectrical measuring, control and laboratory instruments are given inlEC 61010-1. Electromagnetic compatibility (EMC)requirements are given e.g., in theIEC 61326 series. Safety requirements and tests for classification of the sealed sources usedin the gauges are given in iso 2919.
6 Protection against ionizing radiation
6.1
General requirements
The shielding of the gauge shall be so designed, or the gauge shall be installed, in such a ay that the dose equivalent rate at the points which are accessible for non-occupationally exposed persons does not exceed the values specified in appropriate national regulations pertaining to continuously occupied working places.
The accompanying documents shall include information that it is the responsibility of the user to observe the radiation labelling and shielding or barriers and to ensure that the actual limit values, specified in appropriate national regulations, are not exceeded.
The dose rates with the“shutter closed” should be as low as reasonably achievable, e.g.,
Class 7.
Radiation profiles of gauges could be influenced by the individual application on site and shall require additional measurement after installation (see Annex A).
6.2
Requirements for Category A gauges
The source housing shall ensure that the dose equivalent rate for the respective dose rate class is adhered to in accordance with 4.4.IEC 62598 pdf download.