GB/T 16139-1995 Dose conversion factors for neutron radiation protection
Some standard content:
National Standard of the People's Republic of China
Dose conversion coefficients for use inprotection against neutron radiation1 Subject content and scope of application
GB/16139—1995
This standard specifies the conversion coefficients between the practical dose, neutron dose and the basic limit dose commonly used in neutron radiation protection. This standard is applicable to adults. It is not applicable to radiation with a dose of more than 100-1Sv due to radiation effects and other reasons. 2 Reference standards
GF 4792-84 Basic standard for protection of workers and students from radiation 3 Terminology
3.1 Neutron dose
ncutron flux:
The neutron dose at a given point in space is the quotient obtained by dividing the number of neutrons injected into a small sphere centered at the point by the intercept product of the sphere.
3.2 Weakly penetrating radiarion In a uniform, unidirectional ionizing radiation program, for a given human body orientation, such as any small area of the sensitive layer of the skin, if the ratio of the received dose to the effective dose is less than 10, then this radiation is called weakly penetrating radiation. 3.3 Very penetrating radiation In uniform, unidirectional ionizing radiation, for a given human body orientation, if the ratio of the dose received by any small area of the sensitive layer of the skin to the effective dose is less than 10, then this radiation is called very penetrating radiation. 3.4 ICRU sphere ICRU sphere is a tissue equivalent sphere specified by the International Commission on Radiological Units and Measurements (ICRIJ) in its 33rd report. The diameter of the sphere is 33 cm, the density is 1 8/m2, and the element group or by mass is 0.76.2/H, 10.1% C, 11.1% N, 2.6% 3.5 Basic limit value quru:tilyBasic limit value is the quantity used to indicate the basic limit value, that is, the effective dose equivalent (He) and the organ (or tissue) dose equivalent ().
3.6 Practical quantityPractical quantity, also known as operational quantity, is a quantity used in radiation protection practice and has the following characteristics: a: it can be measured by simple monitoring instruments:
b: it can be used as a reasonable approximation of the limit value (neither underestimated nor overestimated) 3.7 Expanded field
The expanded field is a hypothetical radiation field derived from the actual radiation field. 3.8 Axially extended field The National Technical Supervision Bureau approved 1995-12-15 224 Www.bzxZ.net
1996-07-01
CB/T 161391995
A unidirectional extended field is a hypothetical radiation field derived from the actual radiation field, in which the fluence and its energy distribution in the entire relevant volume are the same as the actual radiation field at the reference point, but the fluence is unidirectional. 3.9 Area (or workplace) monitoring Area monitoring is a clinical test conducted to provide data on the radiation environment around facilities and equipment and radiation conditions related to operations. The results of area monitoring are mainly used to classify and predict radiation exposure, and cannot be used to evaluate individual doses. The purpose of area monitoring is to confirm whether the operation and operation conditions meet the requirements. 3.10 Individual monitoring Individual monitoring is to estimate the dose equivalent to human tissues. It is carried out by using a dosimeter worn by an individual and the interpretation of the measurement results. The results of individual monitoring are mainly used to verify the safety of working conditions and to determine unexpected exposures for archiving. 3.11 Ambient dose equivalent
tatnbienl loseeyuivalent H (d) The ambient dose equivalent is the dose equivalent produced by the extended field corresponding to the measuring base point in the ICR sphere in the opposite direction to the radial field and at a depth of d. The recommended value of d is 10m. At this time, (α) is recorded as H (10) 3.12 Directed dose equivalent dieetionllon:uivalent F (l) The directed dose equivalent is the dose equivalent produced by the extended field corresponding to the measuring point in the TCRU sphere in the specified direction and at a depth of . The recommended value of 4 is 0.07 mm: in this case, H(d) is recorded as H(0.07) 3.13 Deep individual dose equivalent, penetrating, H(d) Deep individual dose equivalent is also called penetrating individual dose equivalent. Deep individual dose equivalent applies to strong penetrating radiation. It is the dose equivalent of a group of patients at a depth d below a specified point on the body. The recommended value is 10 mm: in this case, H(d) is recorded as I(15). 3.14 Superficial individual dose equivalent (H,(d)) Superficial individual dose equivalent is used for weak penetrating radiation. It is the dose equivalent of soft tissue at a depth d below a specified point on the body. The recommended value of d is 0.07 mm. In this case, H,(d) is recorded as H1,(0.c7). 3.15 Quality factor Q
The quality factor represents the factor that affects the microscopic distribution of absorbed energy on the biological effect. The Q value used in calculating all conversion coefficients given in this standard can be found in GB4792.
3.16 Irradiation geometry In this standard, irradiation geometry refers to the distance of the incident radiation beam relative to the body or phantom. The four irradiation geometry conditions involved in the various conversion coefficients listed in this standard refer to a wide (actually limited) single-spaced neutron beam, that is, a planar neutron beam. In irradiation geometry, the neutron beam is perpendicular to the axis of the body or phantom. The four irradiation conditions are indicated by the following symbols: AP - irradiation from front to back:
PA - irradiation from back to front:
LAT - irradiation from the side:
R(T) - Rotational irradiation Rotational irradiation can be produced in the following two cases: The neutron field rotates around the body axis at a speed of 0.60 or when the body is stationary, the neutron field rotates around the body axis at a speed of 1.4 Application of practical quantities in neutron protection monitoring
4.1 Ambient dose When H '(a) and directional dose equivalent H(d) The surrounding dose equivalent H(4> is suitable for high-penetrating radiation. The value of "10" at a point in space can be used as an approximate value of the effective dose equivalent received by a human body at that point:
b Directional dose equivalent H\(a) is suitable for weakly penetrating radiation. The value of H(lO) can be used as an approximate value of the dose equivalent received by any sensitive layer (depth 0.07mm>) that is perpendicular to its specified force. H-(10) and H(0. 07) is a practical object used in site monitoring. 4.2 Deep personal dose equivalent, () and superficial personal dose equivalent H, (a) n.: Deep personal dose equivalent H, (:0) is suitable for strong penetrating radiation. H, (10) at a certain point on the front flat part of the trunk can be used as an approximate value of the effective dose equivalent received by the trunk when the AP225
GB/T 16139-1995
condition is sound to L.AT tea conditions. h. Superficial personal dose equivalent H, (0. 07) is suitable for weak negative penetrating radiation. The H, (0. 07) value measured by the dosimeter can be used as an approximate value of the dose equivalent received by the skin near the dose meter, H, (10) and H, (0. 07) is the practical quantity used in personal monitoring. 4.3 Maximum Dose Equivalent in the Phantom (MADE) This is the practical quantity that has been used in protection monitoring for a long time. The so-called phantom passband refers to the equivalent phantom. 5 Conversion coefficient between practical quantity and neutron dose
5.1 The conversion coefficient between practical quantity and neutron dose (\) is used for the development, evaluation and calibration of monitoring instruments. The neutron standard of the national standard laboratory is usually the dose neutron dose basis drawn or inherited 5.2 Appendix A gives the numerical relationship between ┌I'(10) and the conversion and the ambient dose basis equivalent H (10) of unit neutron dose at a series of energy points obtained based on this functional relationship, that is, the conversion coefficient H (: 心)/ (supplement). 5.3 Appendix F gives the directional dose equivalent H (0.07) for H position injection year and the period conversion coefficient H (0.07)/reference) 5.4 Appendix F gives the maximum dose equivalent in the phantom that was injected with a single shot, that is, the conversion coefficient MADE/$(reference) 5.5 Appendix G gives the weekly light quantity H'(10) and the specified dose equivalent H(C.07) per unit neutron injection of some actual neutron sources. That is, the conversion coefficient H(10)/ and H<0.07)/(reference) (H(10) can be regarded as an approximate value of H(10)). 6 Conversion coefficients for practical quantities and basic limit quantities for site monitoring 6.1 gives the ratios of H- to 1T(10). These ratios show that H(10) will not underestimate Iz, and in most cases the degree of overestimation is acceptable, but in some cases it can be overestimated to a higher degree. If the main purpose of monitoring is to optimize radiation protection, the overestimation should be taken into account. Appendix G of Section 6.2 gives the ratio of H1 to H(10) for some actual deuterium sources. This allows us to understand the degree to which H1 overestimates HE in these cases. Appendix C of Section 6.3 gives the ratio of H1 to TF(0.07). These ratios show that, except for cases with higher energies, H(0.07) will not underestimate HE, and the degree of overestimation is generally acceptable. 7 Application of practical quantities for personal monitoring and their conversion coefficients to basic limit quantities 7.1 In radiation measurements, different requirements are placed on monitoring according to the size of the dose. Generally speaking, the larger the dose, the higher the reliability of monitoring should be. 7.2 When the dose equivalent is low (such as the dose involved in type B working conditions, that is, the expected annual dose equivalent may exceed 5mSv, and it is unlikely to exceed 15mSv), the practical amount of personal monitoring can be directly used (that is, there is no need to convert it into the basic limit value for verification. 7.3 When the dose equivalent reaches a higher level (such as the dose involved in type A working conditions, that is, the expected annual dose equivalent may exceed 15mSvr or the dose of slight overexposure in accident situations, that is, slightly less than 5cmSv, or even reaching the dose of special exposure planned in advance, that is, more than 50mSv, less than 100mSv). mS), it should be assumed that the basic limit value is calculated from the practical disk of personal monitoring. In particular, for special exposures planned for completion, the dose evaluation must be carried out according to this value. The data of AP conditions in the radiation record B can be used to convert the dose disk recorded by the personal dose meter (covered with 10mm fabric equivalent material) on the body surface into the effective dose equivalent. The data in the appendix can be used to convert the dose pad recorded by the personal dose meter (with 0.07mm tissue equivalent material) into the skin dose equivalent. Using the Hs/H(10) ratio of some actual neutron sources given in Appendix G, it is possible to understand the degree of H(10) to He in these cases.
8 Conversion coefficients of basic limit value and neutron dose B8.1 Appendix D gives the effective dose equivalent and device dose equivalent per unit neutron dose calculated by the human body model under various irradiation conditions, but the conversion coefficients H/ and H/ are calculated by comparison. The neutron dose is specified in the field in a basic way. When designing (design of process equipment, design of operation and design of monitoring plans, etc.), the data in Appendix D can be used to calculate the effective dose equivalent from the neutron dose (GB/T 16139-1995) or the average dose equivalent of certain organs or tissues. 8.2 Since neutron quantities are also measurable quantities under field conditions, the data in Appendix D are also useful for the interpretation of radiation monitoring results and the evaluation of radiation protection. 8.3 Appendix G gives the effective dose equivalent per unit neutron dose of an actual neutron source, that is, the conversion coefficient He/. 227 GB/T 16139-1995 Appendix A The conversion coefficient between dose equivalent H(10 and neutron dose (Supplementary Material 41) is 0. When 025eV≤20MeV, the conversion function between the ambient dose equivalent H*(10) and the neutron flux H(10)/10-s·cm) is shown in equation (A1).
log ie
1+ (b+ery +I+ exp
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