ISO 18417:2017 pdf download

ISO 18417:2017 pdf download.Iodine charcoal sorbents for nuclear facilities — Method for defining sorption capacity index
1 Scope
The scope of this document covers
— iodine sorbents for nuclear power plants, nuclear facilities, research and other nuclear reactors,
— iodine sorbents for laboratories, including nuclear medicine, and
— iodine sorbents for sampling equipment on sample lines.
This document applies to iodine sorbents manufacturers and operators in order to measure the actual performance of these sorbents and their sorption capacity for radioiodine.
This document applies to granulated and crushed iodine sorbents based on activated charcoal (hereinafter referred to as “sorbents”) used for trapping gaseous radioiodine and its compounds. This document establishes the method and conditions for defining sorption capacity index in a laboratory.
2 Normative references
There are no normative references in this document.
3  Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
3.1 gaseous radioactive wastes
wastes that contain radioactive material in gas form for which no further use is foreseen and have radionuclides at concentrations or activities greater than clearance levels as established by a regulatory body
3.2 discharge
planned and controlled release of (gas or liquid) radioactive material to the environment
3.3 mass transfer zone
defined zone (range) of sorbent volume in which the phenomena of substance mass transfer from gas to solid phases takes place
3.4 iodine sorbent
sorbent intended for trapping radioiodine in gaseous radioactive wastes
4 Principles of the method
The main rationale for the method defined in this document are the following:
— radioactive methyl iodide (CH 3 131 I) is the most difficult form of radioiodine to trap in nuclear facilities discharges;
— the distribution of radioactive methyl iodide along sorbent layer is exponential;
— there is an active mass transfer zone in the sorbent layer;
— the amount of sorbed radioactive methyl iodide depends on the contact time between the gas and sorbent.
The sorption capacity index indicates the degree by which radioactive methyl iodide concentration in gas phase is reduced during the contact of the gas flow with the sorbent.
The principle of the method is the following:
— indoor laboratory air is used as carrier gas;
— air is transferred in the test plant by means of extraction device (fan, vacuum pump, etc.);
— in order to remove indoor laboratory air pollutants, aerosols and humidity, air flow passes through an aerosol filter, an air conditioning system used for humidity (e.g. zeolite or dehumidifier) and volatile compounds removal (e.g. activated charcoal);