This standard specifies the dose measurement content and procedures for the commissioning and daily operation of gamma irradiation equipment for food processing, as well as the classification, selection, calibration and use of gamma ray absorption dose measurement systems. The absorbed dose range applicable to this standard is 0.02kGy~60kGy. GB 16334-1996 Practical Dosimetry Guidelines for Food Processing with Gamma Irradiation Equipment GB16334-1996 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Practical guide of dosimetry in a gamma irradiation facility for food processing1Subject content and scope of application
GB16334---1996
This standard specifies the content and procedures of dose measurement in the commissioning and daily operation of food processing irradiation facilities, as well as the classification, selection, calibration and use of irradiation absorption dose measurement systems. The absorbed dose range applicable to this standard is 0.02kGy~60kGy. Irradiation of other products should also be implemented by reference. Food processing irradiation equipment (hereinafter referred to as irradiation equipment) is a device composed of radiation sources and related facilities for processing irradiated food. Irradiation equipment must meet the safety, hygiene and effectiveness requirements of food processing. The establishment and operation of irradiation equipment must comply with legal approval procedures and be subject to supervision by law enforcement agencies in accordance with the law. Irradiation equipment must be equipped with a dose measurement system. The system should be regularly verified and calibrated, and the traceability of the value should be maintained. The range and error of measuring radiation absorption dose should meet the requirements of process and regulations. 2 Reference Standards
GB139 Standard Method for Determining Absorbed Dose in Water Using Ferrous Sulfate Dosimeter 3 Significance and Use
3.1 Irradiated food is a food that has been irradiated with a certain dose of ionizing radiation and approved by the state for sale in the market in order to achieve certain practical purposes and utilize certain radiation chemical and radiation biological effects produced by ionizing radiation in food. The dose limits specified in the irradiated food hygiene standards approved and issued by the Ministry of Health are listed in Appendix A.
3.2 The dose absorbed by irradiated food depends on many factors, such as the radiation source (type, activity and arrangement), irradiation time, product composition, stacking density, stacking method and packaging, and the geometric configuration between the source and the product. In order to ensure that the food obtains the required dose, the appropriate dose measurement system and procedures should be correctly selected and strictly operated in accordance with the specifications. 3.3 Irradiated food is related to the health of consumers, so the state conducts legal management of its production, storage and sales, and has formulated a series of mandatory management methods and technical standards. Food irradiation must comply with the Food Hygiene Law, the Regulations on the Hygiene Management of Irradiated Food, and the Interim Regulations on the Metrological Supervision and Management of Radiation Processing, and meet the requirements of the corresponding irradiated food hygiene standards and metrological technical specifications. 3.4. The absorbed dose of irradiated food should not be less than the required minimum dose, and should not exceed the statutory average dose limit (or maximum dose limit). Correct dose measurement provides independent, quantitative, and reliable irradiation process control and product quality assurance, promotes the trade of irradiated food, and can serve as a basis for legal supervision and management.
4 Terminology
4.1 Absorbed dose
The quotient obtained by dividing ds by dm, that is, D-dz/dm, where d is the average energy given by ionizing radiation to a substance with a mass of dm. The unit name of the absorbed dose is gray, symbolized by Gy, 1Gy=1J/kg. Approved by the Ministry of Health of the People's Republic of China on June 19, 1996 and implemented on September 1, 1996
4.2 Static batch irradiation
GB 16334--1996
Products are placed in batches at fixed irradiation positions. During the irradiation process, the radiation source and the products do not move. 4.3 Dynamic continuous irradiation
Products are irradiated evenly and continuously through the radiation field at a certain transmission speed. 4.4 Dynamic step irradiation
Products are sent into the irradiation room, stay at the station for a certain period of time, then move to the next irradiation station and stay for the same period of time, and move forward in sequence until they are sent out of the irradiation room.
4.5 Product flow irradiation
Some products such as wine, grains, flour, etc. are irradiated while flowing through the radiation field without packaging. 4.6 Product irradiation box (unit)
A cargo box, shelf or pallet that carries one or more product packages as a whole and passes through the irradiation field. 4.7 Dose measurement system
A system for measuring doses consisting of dosimeters, related analytical instruments and dose response calibration curves (or dose response functions). 4.8 Product dose distribution
Refers to the dose of each part of the product in all irradiation boxes after a certain product is irradiated according to the specified processing technology. 4.9 Dose non-uniformity
The ratio of the maximum to the minimum absorbed dose in the product, that is, U=Dmax/Dmine4.10 Total average dose of the product
The arithmetic average of the measured values ​​of all dosimeters arranged to measure the dose distribution in a given irradiated product, that is, D4.11 Reference dosimeter
A standard dosimeter that can reproduce the absorbed dose unit in an absolute way, has the highest metrological performance, and has been identified and approved by the state as the highest reference for the unified national absorbed dose unit value. 4.12 Standard dosimeter
Has good metrological performance and has passed the assessment in accordance with the law. It can be used to calibrate radiation fields and work dosimeters. Its value can be directly traced back to the national reference dosimeter.
4.13 Transfer standard dosimeter
A standard dosimeter with stable and strong performance. It can reliably transfer the absorbed dose value, carry out mail comparison, calibrate working dosimeters and calibrate radiation fields.
4.14 Working dosimeter (conventional dosimeter) is a dosimeter that has been calibrated by a standard dosimeter and is used to measure the radiation field dose rate and product absorbed dose for daily dose monitoring. 4.15 Tidal source
The characteristic that the measurement results can be linked to the national metrological reference through a continuous comparison chain. 5 Irradiation device
5.1 Irradiation devices can be divided into four types according to the irradiation method: static batch, dynamic continuous, dynamic step and product flow. 5.2 The radiation source used in the irradiation device is mainly Co or 137Cs radioactive nuclides, which can be composed of many rod-shaped elements into a linear, plate-shaped or circular shape.
5.3 The source size exceeds the boundary of the product irradiation box, the radioactivity of the source at the edge of the source rack is increased, the product irradiation box is irradiated from multiple sides, multiple channels and multiple layers along the source, the distance between the source and the product is increased, and the thickness of the product irradiation box is reduced. These methods can improve the product dose non-uniformity and obtain appropriate energy utilization.
6 Activation of irradiation device
GB16334-1996
6.1 Before the irradiation device is activated, detailed rules for food irradiation production management should be formulated, and the operating procedures, safety rules, process dose selection, product packaging and loading methods, quality control of food before and after irradiation, irradiation practice and dose monitoring, and job responsibilities of various personnel should be clearly stipulated and implemented. 6.2 The irradiation device should meet the following conditions in terms of dose measurement: 6.2.1 The dose measurement system, supporting facilities and working environment conditions must meet the needs of processing and production, and pass the inspection in accordance with the law. 6.2.2 The dose test personnel should undergo special training and pass the assessment. 6.2.3 Rules and regulations for achieving quality assurance of absorbed dose measurement. 6.3 Before the irradiation device is put into use, the device acceptance and start-up dose measurement should be carried out. The purpose of device acceptance is to verify whether the irradiation device meets the various design indicators, whether the operation, control and recording of various equipment are normal, and whether the shielding and interlocking are safe and reliable. Start-up dose measurement includes measuring the repeatability of the radiation source to the irradiation position, the irradiation field (dose distribution), and the relationship between the irradiation time and the total average dose in products with different stacking densities, so as to confirm the dose, dose distribution and dose non-uniformity of the products within the typical density range under specific irradiation conditions, as well as their accuracy and repeatability.
6.4 The purpose of measuring the dose distribution of products is to obtain the average dose value and dose non-uniformity, as well as to determine the location of the maximum dose and the minimum dose, and select the daily dose monitoring location. The dose distribution should be measured by evenly arranging dosimeters in a three-dimensional grid throughout the product or simulated product irradiation box and measuring over a wide range of product density. For dynamic irradiation, the irradiation room must be filled with irradiation boxes of the same product or simulated product. In order to ensure the accuracy of the dose distribution measurement, considering the deviations due to the statistics of the irradiation process, the fluctuation of the product stacking density, the fluctuation of the set operating parameters, and the uncertainty of the operating parameter measurement and the dose measurement itself, usually no less than three irradiation boxes are measured.
6.5 In dynamic irradiation, when the product irradiation box begins to enter the irradiation room, all irradiation positions of the half irradiation room at the entrance should be filled with simulated product irradiation boxes to avoid the average dose of the products in the first few irradiation boxes being too high. This treatment also applies to the end of processing, and a sufficient number of simulated product irradiation boxes should be followed by the product irradiation box. When changing products, if the stacking density of two products is similar to the required dose, different dose treatments are used, and simulated products are used to isolate the two products. When the previous product just leaves the irradiation room, the room should be filled with simulated products. At this time, the operating parameters can be adjusted to make it suitable for the processing of the next product. 6.6 For static batch irradiation, the dose distribution of the empty field must be measured in advance, the isodose curve must be drawn, the exact position and method of product stacking must be selected, and the reasonable procedure for product flipping and shifting must be determined. Through the measurement of product dose distribution, verify whether the dose non-uniformity meets the process requirements. Determine the relationship between dose and irradiation time for products of different densities and various stacking flipping methods. 6.7 When the activity and structure of the radiation source and other factors that may affect the dose distribution change, the dose distribution should be re-measured. 6.8 The radiation field should be set with calibration points. The calibration points are located in water phantoms or solid phantoms made of polystyrene or plexiglass, and the distance from the radiation source is about 0.3m~0.6m. They must be strictly positioned. The calibration points can be used to calibrate the working dosimeter and monitor the repeatability of the radiation source to the irradiation position.
7 Daily dose monitoring of irradiation equipment
7.1 In the daily operation of the irradiation equipment, the processing control is generally carried out by monitoring the irradiation process parameters, but daily dose monitoring is still a necessary means to ensure the quality of radiation processing.
7.2 Daily dose monitoring requires that the dosimeter be placed at the maximum dose or minimum dose position of the product irradiation box, or at a location that is convenient for loading and unloading, but the relationship between the dose value at this location and the maximum dose or minimum dose has been determined, recorded, and can be reproduced. 7.3 For dynamic irradiation, at least the dosimeter should be placed in the first, middle and last three irradiation boxes in each batch of products, and it is ensured that at any time there is at least one dosimeter monitoring in the irradiation room. During static irradiation, at least one dosimeter is placed in each batch (type) of stacked products to monitor the absorbed dose value. At the same time, other processing control parameters are monitored and recorded, such as the location of the radiation source, the transmission status of the product irradiation box, the pause time (or transmission speed), the start and stop time, the irradiation interruption caused by the fault, the radiation level, temperature, and degree in the irradiation room, etc. 7.4 In addition to the above-mentioned sampling monitoring of the absorbed dose of the product, the irradiation field should be calibrated regularly, the product dose non-uniformity should be checked, and the operating parameters of the device and their relationship with the absorbed dose of the product should be inspected. GB 16334—1996
7.5 A visual irradiation indicator sheet should be affixed to the product box, which can be used as a stock mark to distinguish between irradiated and non-irradiated products, and can also be used to roughly judge the irradiation situation when the irradiation is interrupted.
8 Classification and use of dosimeters
8.1 According to the metrological performance and use, dosimeters can be divided into three categories: reference dosimeters, standard dosimeters, and working dosimeters. Commonly used standard dosimeters and working doses are listed in Appendix B.
8.2 The transfer standard dosimeter is a standard dosimeter with outstanding performance in terms of good stability and high precision, and can reliably transfer absorbed dose values ​​between the standard laboratory and the user. This type of dosimeter also has the characteristics of easy calibration, no significant dependence of response on radiation energy, dose rate and environment, small and strong, wide measurement dose range, radiation absorption characteristics equivalent to products, and system errors that can be corrected. 8.3 Working dosimeters can be used to measure the dose distribution in the radiation field and products and to conduct daily dose monitoring to control the processing technology and ensure product quality. Working dosimeters should be regularly calibrated in accordance with the National Metrology Verification Regulations (JJG775--92) to establish and maintain value traceability. 9 Selection and calibration of working dosimeters
9.1 Select a suitable working dosimeter according to the purpose and conditions of the application, with specific reference to the following factors: 9.1.1 The range of absorbed dose measurement is suitable for the requirements of the product process. 9.1.2 It has a definite, important and stable dose response curve (function), and the system error can be controlled or corrected. 9.1.3 The dose measurement system is easy to operate, stable and reliable. 9.1.4 The influence of environmental conditions (such as temperature, humidity and light) on the irradiation response and its reading. 9.1.5 The dependence of radiation response on radiation energy spectrum, dose rate and dose administration method. 9.1.6 The influence of the composition (batch) of dosimeters on the measurement of absorbed dose. 9.2 When using standard dosimeters to calibrate working dosimeters, the following points must be noted: 9.2.1 The method of calibrating dosimeters is substitution method, that is, first use the standard dosimeter to calibrate the absorbed dose rate of the calibration point in the radiation field, then place the working dosimeter to be calibrated at the calibration point, irradiate different absorbed doses, measure the radiation response, draw the dose response curve or directly obtain the dose response function.
9.2.2 When calibrating dosimeters in the radiation field, it is necessary to ensure that the secondary electron balance is achieved between the dosimeter and the surrounding similar medium. The irradiated phantom should be strictly fixed in the radiation field, and the calibration point can be accurately reproduced. 9.2.3 The radiation and environmental conditions during calibration, such as dose rate, radiation energy spectrum, beam direction, temperature, humidity, light, atmosphere, etc., should be as close as possible to those used at the irradiation site.
9.2.4 Use water as a reference material and calibrate uniformly to the water absorbed dose. 9.3. The error of the measured value of the working dosimeter must take into account the following factors: 9.3.1 Radiation factors: radiation type, dose rate, energy distribution, beam direction, dose range, dose administration method (continuous or fractionated). 9.3.2 Environmental conditions: temperature, humidity, light, atmosphere, surrounding scatterers during irradiation, temperature, humidity, and light of the dosimeter during storage before irradiation and after irradiation to measurement. 9.3.3 Dose measurement system: composition, thickness, uniformity, production batch, serial storage time, stability, solidity, quality control method of the dosimeter, error and environmental conditions during calibration, standardization of analytical instruments and analytical methods. 10 Records and Archives
10.1 The contents and data related to product quality, irradiation process control, and dose monitoring must be recorded during the acceptance, commissioning, and daily operation of the irradiation device. The records must be signed by the operating personnel, dose monitoring personnel, and the person in charge, and archived for future reference. 10.2 The contents related to dose measurement during the commissioning and daily operation of the irradiation device, such as product name, number, batch number, irradiation date, product stacking density, loading method, absorbed dose, dose distribution unevenness, and the type, arrangement, and nominal activity of the radiation source. 10.3 Monitor the processing parameters that affect the absorbed dose, such as irradiation time, product placement and transmission conditions. 666
GB16334—1996
10.4 Conventional dose measurement methods and data used to measure the absorbed dose and dose distribution of irradiated products, including the manufacturing unit model and batch number of the dosimeter, the reading instrument, the monitoring position in the irradiation box, and the product absorbed dose. 10.5 Calibration data of dosimeters, including date, standard or transfer standard, calibration device used, calibration method, and establishment of traceability. 10.6 Environmental conditions for irradiation of working dosimeters, including temperature, humidity, light, nitrogen, etc. 10.7 Preparation or source of working dosimeters and routine maintenance, verification and use of analytical instruments. 10.8 Estimation of uncertainty of absorbed dose measurement value, precision of measurement results and total uncertainty under a certain confidence level. 11 Error analysis
11.1 The uncertainty of measurement results is an important indicator of measurement quality, which characterizes an assessment of the measured value within a certain range of values. The uncertainty of measurement results includes all components, which can be divided into two categories AB according to their estimation methods: Class A components, standard deviations calculated by statistical methods for repeated measurements; Class B components, approximate "standard deviations" estimated by other methods. The "standard deviation" synthesized by the usual method of synthetic variance (i.e., the square root of the sum of squares of each component) is called synthetic uncertainty. In order to increase the confidence probability, it is necessary to multiply the combined uncertainty by the confidence factor K, take K=2, and get the total uncertainty under 95% confidence probability. 11.2 Precision indicates the degree of random error in the measurement result (belongs to Class A uncertainty), usually including at least two sources: the true response of the dosimeter and the measurement of the response by the reading instrument. The specific value can be determined by multiple measurements of the specific absorbed dose by several dosimeters. If the precision changes, the measurement precision must be recalibrated. 11.3 Deviation includes all non-random factors (belonging to Type B uncertainty) that contribute to the total uncertainty of the measurement result, including the deviations associated with the standard dosimeters and calibration devices used to establish traceability to national standards and the impact of differences in various conditions and factors in calibration and on-site photography.
Irradiated food
Peanut kernel
Potato
Raw peanut kernel
Dried potato wine
Cooked meat products
Inhibition of germination
GB16334--1996
Appendix A
Dose limits specified in the hygienic standard for irradiated food (reference)
Dose (D) or overall
Purpose of irradiation
Killing of storage pests
Fresh-keeping and storage
Inhibition of germination
Killing of storage pests
Inhibition of germination
Fresh-keeping and sterilization to extend shelf life
Fresh-keeping, anti-rot, extended shelf life
Tea fungus, fresh-keeping, extended shelf life
Fresh-keeping, anti-mildew, extended storage period
Sterilization, deinsectization, extended storage period
Prevent insects, reduce losses
Fresh-keeping, anti-rot, extended shelf life
Inactivate Trichinella spiralis, improve sanitary quality
Fresh-keeping, anti-rot, extended shelf life
Fresh-keeping, anti-rot, extended shelf life
Improve the quality of dried potato wine, improve its qualityFresh-keeping, sterilization, extended shelf life
Average dose (D) limit
Standard number
ZB C53 001 -84
ZB C53 002---84
ZB C53 003---84
ZB C53 004---84
ZB C53 005 -84
ZB C53 006---84
Provisional, unnumbered, approved by the Ministry of Health in 1984 GB 9980-- 88
GB 14891. 1---94
GB 14891. 2--94
GB 14891. 3-- 94
GB 14891, 4--- 94
GB 14891. 5-94
GB 14891. 6---94
GB 14891. 7--94
GB 14891.8-m94
GB 14891. 9--~94
GB14891.10--94
Calorimeter
Dosemeter
Ferrous sulfate (Fricke)1)
Potassium dichromate (silver)
Silver dichromate
Alanine
Cerium-disulfate
Chlorophenylethanol
Ferrous sulfate-copper
Glutamine
Dyed plexiglass (PMMA)
Colorless and transparent plexiglass (PMMA)
Cellulose triacetate
Radiochromic film, solution, optical waveguide
1)Perform according to GB139.
Additional notes:
GB16334-1996
Appendix B
Common standard dose meters and working dose meters (reference)
Analysis method
Calometry (thermistor or thermocouple)
Ultraviolet spectrophotometry
Visible spectrophotometry
Visible spectrophotometry
Electron spin resonance
Ultraviolet spectrophotometry or potentiometric method
Colorimetric titration, high-frequency oscillography or spectrophotometry Ultraviolet spectrophotometry
Crystal sol-luminescence
Visible spectrophotometry
Ultraviolet spectrophotometry
Ultraviolet spectrophotometry||t t||Visible spectrophotometry
Dose range
103～105
4×10～4×102
5×103~5×10
5×102～5×10*
5×103～4×104
102~105
103～8×103
102～4×104
103～5×104
103~105
10~4×105
PrecisionbZxz.net
(S./3)X100
This standard is under the technical jurisdiction of China National Institute of Metrology. This standard was drafted by the China Institute of Metrology, with participation from the Second Research and Design Institute of Nuclear Industry and the Shanghai Institute of Nuclear Research. The main drafter of this standard is Li Chenghua, and the participating drafters are Wang Chuanzhen, Wu Zhili, Gao Juncheng, and Pang Ruicao./3)X100
This standard is under the technical supervision of the National Institute of Metrology. This standard was drafted by the National Institute of Metrology, and the Second Research and Design Institute of Nuclear Industry and the Shanghai Institute of Nuclear Research participated in the drafting. The main drafter of this standard is Li Chenghua, and the participating drafters are Wang Chuanzhen, Wu Zhili, Gao Juncheng, and Pang Ruicao. 669/3)X100
This standard is under the technical supervision of the National Institute of Metrology. This standard was drafted by the National Institute of Metrology, and the Second Research and Design Institute of Nuclear Industry and the Shanghai Institute of Nuclear Research participated in the drafting. The main drafter of this standard is Li Chenghua, and the participating drafters are Wang Chuanzhen, Wu Zhili, Gao Juncheng, and Pang Ruicao. 669
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