GB 12951-2009Americium-241 alpha sources for ionization smoke fire detectors (English PDF)

3.1 Structure

Am alpha source should be part of americium 241alpha source sheet, the source holder and the like. alpha-chip source and the source holder should fit properly without being loose.

3.2 Requirements for raw materials

3.2.1 Radionuclide and impurities

Nuclide. americium 241 (241Am); gamma impurity content of not more than 1%.

3.2.2 Overburden material

Cover material should be gold-palladium alloy or other equivalent material.

3.2.3 Source scaffold

Source scaffold should be used 1Cr18Ni9Ti, 0Cr18Ni10Ti or other equivalent material.

3.3 Safety rating

Am alpha source safety performance level should not be less than GB 4075-2009/C32222.

Appearance 3.4 Am alpha source Americium alpha Yuanyuan sheet surface should be smooth, no cracks, no discoloration, no pinholes, no scratches and the like. Surface source mount and the source of the base should be smooth, no glitches.

3.5 Am alpha source activity

Am alpha source of radioactivity should be limited to 370kBq. Total uncertainty Am alpha source activity test value shall not exceed ± 10%.

alpha alpha spectrum 3.6 americium source for alpha particles alpha americium peak energy source in 3.0MeV ~ 4.0MeV range of its spectrum of alpha particles should be less than half width 1.2MeV; alpha of 4.0MeV above americium source that alpha particle energy spectrum FWHM should not exceed 0.8MeV.

Surface emissivity 3.7 alpha particle dispersion Dispersion alpha particle surface emissivity Am alpha source shall not exceed the nominal value ± 20%.

3.8 Surface Contamination

Am alpha source of surface contamination should not exceed 200Bq.

3.9 Environmental Testing

Environmental testing results Am alpha source should meet EJ/T 535 requirements.

3.10 Term

Under normal conditions of use americium source alpha period of 5 years.

Test Method 4

4.1 safety rating tests carried out according to the provisions of GB 4075.

4.2 appearance test by visual inspection.

4.3 Am alpha source activity, alpha particle energy, alpha particle surface emissivity spectrum test shall use the methods provided in Appendix A or other eligible the method of testing requirements were.

4.4 Am alpha source alpha particle surface emissivity test may be used to test the value of the uncertainty of alpha counts less than 10% of the measuring device to be tested.

4.5 level surface contamination and leakage tests carried out according to the provisions of GB 15849.

4.6 Environmental Testing conducted by EJ/T 535 requirements.

5.1 Overview

Product inspection is divided into type test and factory inspection. Am alpha source of performance tests made at the time of type testing and factory inspection, see Appendix A.

5.2 Type inspection

The standard 3.1 to 3.9 for the type inspection items. Wherein. 3.2,3.3,3.5,3.6,3.7 is always checked.

When the following conditions occur, you should type inspection.

a) the development of new products;

b) products in the design, specification, technology and materials have significant changes;

c) the production of varieties not often when production again;

d) mass production of bulk products, sampling should be carried out regularly.

Type inspection items include.

a) safety performance rank test;

Index Test b) Am alpha source activity, alpha and alpha particle spectrum particle surface emission rate;

c) the level of surface contamination and leakage test;

d) Environmental testing.

5.3 Factory inspection

Factory inspection items include.

a) visual inspection;

b) alpha particle spectra;

c) alpha particle surface emissivity index testing;

d) surface contamination;

e) the level of leakage test.

5.4 Sampling Inspection Method

Sampling inspection method according to GB/T 2828.1 regulations or GB/T 6378's. Wherein the test level and acceptable quality level (AQL) refers to Determination in consultation by both parties.

6.1 Logo

Am alpha source product logo, may be provided in the form of product inspection certificate.

6.2 Inspection certificate

Production unit of manufactured products, provide product inspection certificate delivery units. Inspection Certificate includes.

a) radioactive source name, source model and lot number;

b) a source of safety performance level test results;

Activity c) sources, alpha and alpha particle energy particle surface incidence of technical specifications;

d) the level of surface contamination and leakage test results;

e) test basis;

f) production units and inspection certificate issuer, date of inspection.

7.1 Packaging and Transport

Packaging and transportation Am alpha source according to the requirements of GB 11806 was.

7.2 Storage

Am alpha source should be stored in ventilated, dry and non-corrosive gas environments.

Appendix A

(Informative)

Am alpha source Performance Measurement A. 1 cover layer uniform Am alpha source energy measurement A. 1.1 measuring instruments and their requirements A. 1.1.1 gold silicon surface barrier detectors. The indicators should be consistent with GB/T 5201 requirements.

A. 1.1.2 linear amplifier and pre-amplifier. The indicators should be consistent with GB/T 4079 requirements.

A. 1.1.3 computer multi-channel amplitude analyzer. The indicators should be consistent with GB/T 4833.1 requirements.

A. The total uncertainty of the measurement systems 1.1.4 ± 5%.

A. 1.2 Measurement Methods A. 1.2.1 using three or more different energy sources for alpha standard multi-channel amplitude analyzer energy scale.

A. 1.2.2 scales used alpha sources of self-absorption on the measurement results, it should ensure that it can be ignored or can be corrected.

A. 1.2.3 scales according to conditions Am alpha source of energy measurement. Measurement should be kept constant measurement conditions.

A. 1.2.4 Even if the result of the determination based on a computer analysis of the corresponding energy, the method can also be used to calculate the corresponding energy obtained.

A. 2 cover layer uniform Am alpha source activity measurement method A. 2.1 small solid angle measurement device A. 2.1.1 measuring device and its requirements Measuring apparatus and its requirements include.

a) small solid angle unit. Made of stainless steel tube processing. Shall be accurate and reliable positioning plate and collimator to maintain the source and the collimator the concentric and parallel. It should ensure that the device may be evacuated to 0.67Pa less.

b) detector. It may be indicators in line with GB/T 5201 requirements of the surface barrier semiconductor detector or using CsI (Tl) crystal thin Scintillation detector.

c) automatic scaler. Threshold should be continuously adjustable. Using computer multi-channel pulse amplitude analyzer automatic calibration device may also be used.

System d) measuring means total uncertainty of less than ± 5%.

A. 2.1.2 Measurement Measurement method comprising.

a) When using gold silicon surface barrier detectors, shall be measured according to GB/T 5201 requirements of the selected measurement conditions.

b) shall be measured to ensure that the degree of vacuum means less than 1.33Pa.

c) shall ensure that the measuring device the minimum measurable signal amplitude corresponding to the alpha particle energy measurement conditions.

Before using the device should be used 241Am standard source of stoichiometry; put into use, it should be measured regularly compared.

A. 2.1.3 Data Processing the formula of measurement results (A.1) as follows.

A0 = like 0G · eta

Where.

A0 --- Am alpha source activity in units of Baker (Bq);

Like alpha 0 --- corrected count rate in units of cps;

G --- with 4l normalization of geometry;

eta --- and measurement conditions independent of detector efficiency.

A. 2.2 low energy photon measurement methods A. 2.2.1 measuring device and its requirements A. 2.2.1.1 Detectors may be NaI (Tl) scintillation crystal thin detector, semiconductor detector may be used. When using NaI (Tl) thin crystal, the crystal window it should be thin beryllium windows or aluminum windows.

A. 2.2.1.2 linear amplifier and preamp the indicators of the instrument should be consistent with GB/T 4079 requirements.

A. 2.2.1.3 Automatic scaler Threshold should be continuously adjustable. The computer may also be multi-channel pulse height analyzer. It should ensure that the total uncertainty of the measurement system means little 5%.

A. 2.2.2 Methods of measurement and data processing A. 2.2.2.1 During the measurement should be consistent measurement conditions, americium alpha source shall be aligned with the front of the detector, the distance between americium alpha source and detector can be Nominal size is determined based on the activity of alpha americium source.

A. 2.2.2.2 according to selected criteria, set screening thresholds to measure or obtain alpha americium source from the entire spectrum curve measured in 0.0596MeVgamma Ray photoelectric peak pulse count within. Then according to the source peak detection efficiency means obtains gamma photons emitted Am alpha source.

A. 2.2.2.3 According to americium 241 isotope decay exact figure has been known gamma photon energy and the relationship between the branching ratio by the gamma 0.0596MeV gamma photon emission rate of photon yield and measured, calculated Am alpha source activity.

A. 2.2.2.4 should be used regularly 241Am standard source for calibration of the measurement device.

references

[1] GB/T 4079 for ionizing radiation detectors charge sensitive amplifier and pre-amplifier test methods [2] GB/T 4833.1 multi-channel analyzer - Part 1. Technical requirements and test methods [3] GB/T 5201 Test Method for semiconductor charged particle detectors