CN201047875Y

CN201047875Y - Modified type A-B neutron ''Rem'' counter

Info

Publication number: CN201047875Y
Application number: CNU200620118398XU
Authority: CN
Inventors: 李建平
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-06-12
Filing date: 2006-06-12
Publication date: 2008-04-16
Anticipated expiration: 2016-06-12

Abstract

The utility model discloses an improved A-B neutron Rem counter including a neutron nomotron (3), an inner moderation body (2) surrounding the neutron nomotron, an absorber (4) surrounding the inner moderation body, and an outer moderation body (1) surrounding the absorber. The improved A-B neutron Rem counter is characterized in that a high-energy neutron moderation body (5) is provided between the absorber (4) and the outer moderation body (1). The utility model extends the response range of measuring neutron energy from 0.025eV-20MeV to 20MeV-1GeV, thereby improving the sensitivity of the instrument. The energy response character of the utility model is verified on the both sides of the theory and the practice, thereby solving the safe monitoring problem of the high energy neutron (above 20MeV).

Description

Modified A-B neutron " rem " counter

Technical field

The utility model belongs to the nuclear safety monitoring technical field, specially refers to a kind of modified A-B neutron " rem " counter.

Background technology

Along with domestic and international Nuclear Science and Technology development, the construction and the operation of novel nuclear facilities such as large-scale particle accelerator, spallation neutron source, nuclear clear energy sources.Produce neutron, γ radiation in its surrounding environment, wherein the neutron irradiation energy is greater than the quite high ratio of occupying of 20MeV.What current measurement neutron dose equivalent was general both at home and abroad is Andersson-Braun neutron " rem " counter (being called for short general A-B neutron " rem " counter), its basic structure comprises successively neutron counter tube from inside to outside, interior slow body, absorber, outer slow body (with reference to figure 1), this counter measures neutron energy scope is to 20MeV from thermal neutron 0.025eV, the subject matter that exists is: it is not enough to measure the neutron energy scope for novel nuclear facilities, for neutron greater than 20MeV, this counter sensitivity sharply descends, and is promptly insensitive.For addressing this problem, someone proposes a kind of modified A-B neutron " rem " counter of imagination, promptly in general A-B neutron " rem " counter structure, add high-energy neutron slow body (lead layer) and can make the above moderation of neutrons of 20MeV, improve and survey high-energy neutron sensitivity.But never theoretical and experimentally verified.

The utility model content

The purpose of this utility model provides a kind of modified A-B neutron " rem " counter, it is verified above-mentioned imagination structure from theoretical and experimental technique; the And proof adds the 10mm lead layer in general A-B neutron " rem " counter centre just can reach the optimum capacity responding range, is method validation by experiment first both at home and abroad.

At existing neutron dose equivalent instrument existing problems, made a concrete analysis of the low reason of its sensitivity, when neutron energy during greater than 20MeV, slow body (tygon) the slowing down effect of general A-B neutron " rem " counter is not enough, surveys so be not counted the thermal neutron counter tube at device center.Therefore sensitivity descends.Need searching can make the above moderation of neutrons material of 20MeV for this reason, find that heavy metal material (as lead, tungsten etc.) all can make the above neutron of 20MeV by the inelastic scattering slowing down, is called high-energy neutron (more than the 20MeV) slow body.

The technical solution of the utility model is: a kind of modified A-B neutron " rem " counter is provided, it comprises neutron counter tube, surrounds the interior slow body of neutron counter tube, surrounds the absorber of interior slow body and the outer slow body that surrounds absorber, it is characterized in that, absorber and outside between the slow body, be provided with the high-energy neutron slow body.

Further, described high-energy neutron slow body is to be made by the material of leaded or W elements, and its thickness is 10mm.

When the neutron energy is lower than 20MeV when following, elastic scattering takes place with plumbous nuclear in incident neutron, off-energy not that is to say that this layer lead is " transparent " to the following neutron of 20MeV, so its existence can not influence former A-B neutron " rem " counter to the original response of low energy neutron.When high-energy neutron incident when the lead layer, inelastic scattering takes place with lead nuclear, give plumbous nuclear with a part of NE BY ENERGY TRANSFER, and make high-energy neutron by slowing down, easily detected, so the adding of this one deck lead has improved its energy response to high-energy neutron by neutron counter tube.

Said structure parameter (technical scheme) needs from theoretical and experiment two aspects checking.

The utility model has at first calculated the energy response scope of improved structure parameter, result of calculation show modified A-B neutron " rem " counter can the scope of sound can be from 0.025eV to 1GeV ， And and meet with response curve that ICRP recommends.

There is quite big difficulty in this utility model experimental verification:

(1) domesticly do not set up accurate monochromatic neutron energy as yet, checking is provided greater than the 20MeV standard neutron source;

(2) the above accurate monochromatic neutron source of the 20MeV that produces, beam cross section is enough big, can demarcate detector and cover.

Having finished the high-energy neutron energy on Japanese atomic force laboratory, the research institute East Sea and northeastern Japan university accelerator is 22.0MeV, 32.5MeV, 40.2MeV, 45.4MeV, 64.7MeV, the checking of five energy points, experimental result shows this utility model structural parameters, improve the energy response scope, met ICRP typical curve (Figure of description 2).This is the confirmatory experiment of finishing first both at home and abroad, also is the foundation that this utility model is made.

Description of drawings

Fig. 1 is the diagrammatic cross-section of modified A-B neutron " rem " counter;

Fig. 2 is that modified A-B neutron " rem " counter (M95-2) can ring curve.

Wherein, neutron fluence rate sensitivity is contrasted with (eV) energy variation curve And and general A-B neutron " rem " counter, M95-2 is the variation of the fluence rate sensitivity of modified A-B neutron " rem " counter with energy, shows that its variation meets ICRP (ICRP) typical curve.

Embodiment

Embodiment: Figure 1 shows that modified A-B neutron " rem " counter, it comprises Φ 25 * 100mm cylindricality BF ₃Neutron proportional counter tube 3, the outside is surrounded by thick inner layer polyethylene slow body 2 of 18mm and the thick outer layer polyethylene slow body 1 of 79mm, interior slow body 2 and outside the thick bp absorber 4 of 5mm is arranged between the slow body 1, absorber 4 and outside between the slow body 1, the thick lead layer of 10mm 5 is set as the high-energy neutron slow body, this is the optimum configuration of this utility model.Should " rem " counter and the structural parameters that compare of common general detector as shown in table 1.

The concrete structural parameters of implementing of table 1

Model	Widely can distinguish the neutron irradiation dose detector	General neutron irradiation dose detector
Model		General neutron irradiation dose detector	Counter tube size and charge pressure	Φ25×100mm 6×10 ⁴Pa，BF ₃	Φ25×100mm 5×10 ⁴Pa，BF ₃
Lead layer thickness	10mm	Do not have	Counter tube size and charge pressure	Φ25×100mm 6×10 ⁴Pa，BF ₃	Φ25×100mm 5×10 ⁴Pa，BF ₃
Lead layer thickness	10mm	Do not have	Interior slow body thickness	18mm	18mm
Outer slow body size	Φ 254mm, thick 79mm	Φ 216mm, thick 70mm	Interior slow body thickness	18mm	18mm
Outer slow body size	Φ 254mm, thick 79mm	Φ 216mm, thick 70mm	Absorber size, boron content and contain hole amount	Thick 5mm, boron content 28%, Φ 10mm hole 22%	Thick 5mm, boron content 28%, Φ 10mm hole 22%
Type	Modified	Plain edition	Absorber size, boron content and contain hole amount	Thick 5mm, boron content 28%, Φ 10mm hole 22%	Thick 5mm, boron content 28%, Φ 10mm hole 22%

Can ring experiment (Figure of description 2) with " rem " counter of this embodiment what Japan finished five energy points of high-energy neutron.Concrete experimental provision and test result are as shown in table 2.Experimental result shows, modified A-B neutron " rem " counter, for high-energy neutron (22.0MeV, 32.5MeV, 40.2MeV, 45.4MeV, 64.7MeV) energy response is good, has improved fluence rate sensitivity.

Table 2 is finished the device of energy response experiment

Experimental provision	Energy	Nuclear reaction and device	The neutron flux calibrating instrument	Beam monitor
Experimental provision	Energy	Nuclear reaction and device	The neutron flux calibrating instrument	Beam monitor	Japan	Accurate thermal neutron	Graphite stack+Cadmium
Japan	8KeV	⁴⁵Sc (p, n), that rice of ground	6Li，SSD	Long boron F ₃Proportional counter, the proton beam monitor	Japan	Accurate thermal neutron	Graphite stack+Cadmium
Japan	8KeV	⁴⁵Sc (p, n), that rice of ground	6Li，SSD	Long boron F ₃Proportional counter, the proton beam monitor	Beijing University	144KeV	Li (p, n), the 4.5MV electrostatic accelerator	Fill the hydrogen proportional counter	Long boron F ₃Proportional counter
Beijing University	565KeV	Li (p, n), the 4.5MV electrostatic accelerator	The methane proportional counter	Long boron F ₃Proportional counter	Beijing University	144KeV	Li (p, n), the 4.5MV electrostatic accelerator	Fill the hydrogen proportional counter	Long boron F ₃Proportional counter
Beijing University	565KeV	Li (p, n), the 4.5MV electrostatic accelerator	The methane proportional counter	Long boron F ₃Proportional counter	401	2.5MeV	²⁵²The Cf isotope neutron source
This institute	4.5MeV	Pu-Be neutron source			401	2.5MeV	²⁵²The Cf isotope neutron source
This institute	4.5MeV	Pu-Be neutron source			Beijing University	16.62 MeV	T (d, n), the 4.5MV electrostatic accelerator	Scintillation-counter telescope	Long boron F ₃Proportional counter
Northeastern Japan university	22.0MeV	Li (p, n), cyclotron	Proton-recoil telescope	²³²The Th fission chamber, NE213 liquid flashing counting device, proton beam monitor	Beijing University	16.62 MeV	T (d, n), the 4.5MV electrostatic accelerator	Scintillation-counter telescope	Long boron F ₃Proportional counter
Northeastern Japan university	22.0MeV	Li (p, n), cyclotron	Proton-recoil telescope		Northeastern Japan university	32.5MeV	Li (p, n), cyclotron	Proton-recoil telescope	²³²The Th fission chamber, NE213 liquid flashing counting device, proton beam monitor
The Japan Atomic Energy Research Institute	45.4MeV	Al (p, n), the 90MV cyclotron	Proton-recoil telescope, the BC501A scintillation counter	²³⁸U、 ²³²The Th fission chamber, the proton beam monitor	Northeastern Japan university	32.5MeV	Li (p, n), cyclotron	Proton-recoil telescope
The Japan Atomic Energy Research Institute	45.4MeV	Al (p, n), the 90MV cyclotron	Proton-recoil telescope, the BC501A scintillation counter	²³⁸U、 ²³²The Th fission chamber, the proton beam monitor	The Japan Atomic Energy Research Institute	40.2MeV	Li(p，n)	Neutron spectrum measurement time-of-flight method. the neutron fluence rate measurement is to utilize proton-recoil telescope and BC501A liquid flashing counting device	²³⁸U、 ²³²The Th fission chamber
The Japan Atomic Energy Research Institute	64.7MeV	Li(p，n)	Neutron spectrum measurement time-of-flight method. the neutron fluence rate measurement is to utilize proton-recoil telescope and BC501A liquid flashing counting device	²³⁸U、 ²³²The Th fission chamber	The Japan Atomic Energy Research Institute	40.2MeV	Li(p，n)		²³⁸U、 ²³²The Th fission chamber

Claims

1. a modified A-B neutron " rem " counter, comprise neutron counter tube (3), surround the interior slow body (2) of neutron counter tube, the absorber (4) of the interior slow body of encirclement and the outer slow body (1) that surrounds absorber, it is characterized in that, absorber (4) and outside between the slow body (1), be provided with high-energy neutron slow body (5).

2. modified A-B neutron as claimed in claim 1 " rem " counter is characterized in that described high-energy neutron slow body (5) is to be made by the material of leaded or W elements, and its thickness is 10mm.