CN100578681C - Water boiler solution nuclear reactor having inherent security - Google Patents

Abstract

The invention discloses a water-boiler solution-type reactor with fixed security, the concentrated UO2(NO3)2 solution or UO2SO4 solution is as the nuclear fuel, the flat in-core structure is adopted, the ratio of in-core solution height to in-core diameter is 0.3-0.8, when the ratio of volume to power is maintained at 2.0-2.5kW/L, the volume of the in-core solution can achieve 50-200L, the power of heap is bigger than 100kW.

Description

" homogeneous solution-type reactor " solution nuclear reactor with inherent safety

Technical field

The present invention relates to " homogeneous solution-type reactor " solution nuclear reactor, be specifically related to have " homogeneous solution-type reactor " solution nuclear reactor of inherent safety.

Background technology

Be called " homogeneous solution-type reactor " reactor with the uranium salt aqueous solution again as the homogeneity solution nuclear reactor of nuclear fuel.Be characterized in that fuel solution natural convection under the nuclear reaction operating mode (also comprising air-flow rising disturbance) passes to cooling tube or cooling wall with fission heat by convection current.

Nineteen forty-three has proposed this " homogeneous solution-type reactor " reactor concept in the world the earliest, and to have built up in U.S. Los.Alamos National Laboratory with the uranium sulfate aqueous solution in nineteen forty-four be Lopo (zero energy) heap of fuel.It not only provides the critical mass data, and manipulation and control experience also are provided.

Built up the Hypo heap of operation at power Dec nineteen forty-four, it is that fuel changes the uranyl nitrtate aqueous solution into by the uranium sulfate aqueous solution on Lopo heap basis, and heap power is brought up to 1～5.5kW scope.The radgas that the hydrogen or oxygen gas of the bombarded with fragments water generates that produces owing to fission in the solution and fission produce enters atmosphere by diluting, filtering through chimney.Behind the operation hundreds of kW-h, the nitrogen component in the original solution has reduced 30%, is taken away by air, therefore requires to have 6cm ³Sour water/kW-h mends into to guarantee continuous operation.

Nitrogen runs off and the compound water of hydrogen-oxygen returns the heap problem in order to solve, and nineteen fifty is reconstructed into the Supo heap with the Hypo heap, the highest 45kW that once reached of heap power, and fuel solution still is the uranyl nitrtate aqueous solution.This heap is set up airtight air circuit, by catalytic bed hydrogen and oxygen are combined into water, pile next time in condensation, radgas and nitrogen, nitrogen oxide all are sealed in and have avoided the loss of nitrogen in the solution in the air circuit, the U-235 enrichment makes 88.7% into by 14.5%, has significantly reduced by nitric acid to decompose the gas that produces.

More above-mentioned heap types are starting point to pursue minimum critical mass (MCM), do not emphasize the fuel solution dilution and concentrate the inherent safety of introducing negative reactivity under the condition.

Solution reactor is mainly used in neutron activation analysis, neutron is taken pictures and various research work, because succeeding in developing of solid fuel research reactor can provide higher power level and neutron fluence rate level, research reactor has replaced solution reactor gradually.Last century, the nineties because overwhelming majority research reactors in countries in the world are aging, faced the source problem that comes of medical-isotope from now on.The U.S. proposes the conceptual design of medical-isotope production heap (MIPR).This develops the opportunity of having created for solution reactor again, owing in the world nuclear safety is paid much attention to, the exploitation again of solution reactor must be based upon on the more safe and reliable basis.

Russia " Argus " heap is the solution reactor with inherent safety.Be that fuel solution is all introduced negative reactivity no matter concentrate still dilution.Another characteristics are under cooling system inefficacy and control protection system fault condition, rely on the intensification of fuel solution to introduce negative reactivity, make the decline of heap power.The negative reactivity combatting dehydration power void fraction of heat up introducing reduces the positive reactivity of introducing, and heap power is adjusted to and the natural heat dissipation power level that balances each other automatically.This moment, the fuel solution temperature still was lower than the fuel solution boiling temperature.Russia " Argus " heap is 20kW, and ratio of height to diameter is 1: 1, i.e. the 30cm of core diameter, the high about 30cm of solution, the about 20L of liquor capacity.Uranium-235 is 90%, and initial uranium loading amount is 1.5kg, uranium from solution-235 concentration and reserve effecting reaction (K _Eff) change curve sees, uranium-235 critical mass minimum in 60～85g/l scope can realize that solution concentration or dilution introduce negative reactivity.Though this heap has inherent safety, heap power has only 20kW, and productive capacity is low, improve productive capacity, must improve heap power, makes heap promptly have inherent safety and has bigger heap power again.At present, yet there are no the relevant report of heap power both at home and abroad greater than the solution reactor of 100kW inherent safety.

Summary of the invention

The object of the present invention is to provide a kind of " homogeneous solution-type reactor " solution nuclear reactor with inherent safety, its heap power is greater than 100kW.

A kind of " homogeneous solution-type reactor " solution reaction heap of the present invention with inherent safety, its reactor core adopts pancaked core, and reactor core solution height/core diameter's ratio is 0.3～0.8, with the UO that concentrates ₂(NO ₃) ₂Solution or UO ₂SO ₄Solution is as nuclear fuel, and when volumetric specific power maintained 2.0～2.5kW/L, the reactor core liquor capacity can reach 50～200L, and heap power is greater than 100kW.

Aforesaid " homogeneous solution-type reactor " solution reaction heap with inherent safety, its pancaked core that adopts are cylindrical reactor core at the bottom of flat cylindrical reactor core or the dish, and reactor core is divided into inside and outside two districts, and inner region does not have cooling tube, and outskirt is arranged cooling tube; No cooling tube inner region is furnished with control rod guide tube, and the seal welding of going to the bottom of the loam cake of control rod guide tube and core vessel and core vessel is a chilled water in the control rod guide tube, contacts with fuel solution outward; Reactor core solution radially outskirt is furnished with cooling tube fuel inner region, and the cooling tube curl vertically coils, and cooling tube water is flowed to the cooling tube collecting pipe, is passed in and out by the cooling water outlet and inlet pipe again; Reactor core solution top is provided with the reactor core top reflector, and core vessel is provided with water or graphite reflector outward.

Aforesaid " homogeneous solution-type reactor " solution reaction heap with inherent safety is added with flammable neutron poison Gd-155 in its reactor core solution.

Aforesaid " homogeneous solution-type reactor " solution reaction heap with inherent safety, the flammable neutron poison Gd-155 that is added with in its reactor core solution is Gd (NO ₃) ₃Form.

Aforesaid " homogeneous solution-type reactor " solution reaction heap with inherent safety, it adopts the mode that becomes solution uranium concentration and the operation of change power to move.

At design heap power during greater than the solution nuclear reactor of 100kW inherent safety, if, when designing, can make reactor reserve effecting reaction (K according to normal reactor core ratio of height to diameter (1: 1) only by enlarging the reactor core liquor capacity _Eff) big to the stage that is difficult to control.For making K _EffReduce, the present invention adopts the pancaked core structure, by the increase of neutron leakage, K _EffMaximal value with solution uranium concentration change curve moves to uranium-235 concentration minimizing direction, is beneficial to the expansion of reactor core liquor capacity.When the heap specific power maintained 2～2.5kW/L, the reactor core liquor capacity can reach 50～200L.Because the changes of reactivity that pancaked core causes when solution concentration is made up of two parts: the one, the positive reactivity that solution concentration is introduced, another is that the solution height minimizing has increased leakage surface and volume of fuel ratio, introduce negative reactivity, the reactive superposition of these two parts is progressively introduced negative reactivity under the solution concentration condition.The present invention utilizes this principle, has realized the fuel solution dilution and concentrate the inherent safety of all introducing negative reactivity under lower solution uranium concentration.The pancaked core structure that the present invention adopts, also make solution surface amass/increasing of liquor capacity ratio, cavity overflows easily in the solution, when more helping the tripping of forced outage control rod, keep the reactor core solution temperature to be lower than boiling temperature, reactor capability can be reduced to the power that balances each other with natural heat dissipation automatically.

Reactor core is divided into inside and outside two districts among the present invention, and inner region does not have cooling tube, and outskirt is arranged cooling tube, helps K _EffMaximal value with solution uranium concentration change curve moves to the low concentration direction, reduces uranium-235 loading amount.Reactor core solution top air cavity increases the local reflex layer and also helps reducing uranium-235 loading amount.

For at little K _EffUnder prolong the feed supplement cycle, the present invention also adds flammable neutron poison Gd-155 (for example with Gd (NO in reactor core solution ₃) ₃Form), because the Gd-155 neutron-absorption cross-section is moderate, can be so that the reactivity of uranium-235 waste of fuel can be reduced by Gd-155 to be discharged positive reactivity and be compensated, as calculated, less than 1 effective delayed neutron fraction (β _Eff) excess reactivity under, can be at 1000 EFPD (effectively full power sky) with interior not make-up solution.

When isotope extracts, in order to reduce solution loss, to wash with rare nitric acid the solution on the isotope extraction column, this part uranium-bearing washing fluid should return heap, has so just caused the dilution of heap solution, adopts to become the solution uranium concentration and become the power method of operation to solve the solution dilution problem, the ie in solution uranium concentration changes, heap power progressively changes, and when the solution uranium concentration strengthened, heap power automatic or manual rose.Adopt such method of operation, help reducing initial excess reactivity, can make reactor have bigger heap power (greater than 100kW), have inherent safety again.

Effect of the present invention is: because medical-isotopes such as molybdenum-99, sulphur-131 and strontium-89 are the pillar products of nuclear medicine, adopt " homogeneous solution-type reactor " solution nuclear reactor with inherent safety of the present invention, can improve the productive capacity of medical-isotopes such as molybdenum-99, iodine-131 and strontium-89, satisfy market demand, economic benefit, social benefit are considerable, and also neutron activation analysis, neutron photography and neutron being controlled cancer etc. simultaneously has good prospects for application equally.

Description of drawings

Fig. 1 is flat cylindrical core structure synoptic diagram.

Fig. 2 is a cylindrical core structure synoptic diagram at the bottom of the dish.

Among the figure: 1. do not have the cooling tube inner region; 2. core vessel; 3. cooling tube fuel inner region is arranged; 4. control rod guide tube; 5. cooling tube collecting pipe; 6. cooling tube is imported and exported pipe; 7. reactor core top reflector; 8. water or graphite reflector.

Embodiment

Now in conjunction with the accompanying drawings, the present invention is further described:

With 200kw heap power is example, carries out concrete reactor core design.

Embodiment 1

As shown in Figure 1, adopt flat cylindrical core structure, do not contain flammable neutron poison Gd-155 in the reactor core solution.The UO of enriched uranium ₂(NO ₃) ₂Solution or UO ₂SO ₄Solution is placed in the core vessel 2, the 70cm of core diameter's (internal diameter), the high about 70cm of core vessel, high 25～the 32cm of reactor core solution (becoming) with the solution uranium concentration, reactor core solution radially divides inside and outside two districts, 1 of no cooling tube inner region is arranged 3～6 control rod guide tubes 4, control rod guide tube 4 and the loam cake of core vessel 2 and the seal welding of going to the bottom of core vessel 2, in the control rod guide tube 4 is chilled water, contact with fuel solution outside the control rod guide tube 4, reactor core solution radially outskirt is furnished with cooling tube fuel inner region 3, and cooling tube is 20 branch roads, and curl vertically coils.Radiant rays is arranged, is arranged in R=13.5～35.0cm scope, and every radiant rays is around 13 circles, and caliber is Φ 8 * 1.5.20 branch road cooling tube water are flowed to cooling tube collecting pipe 5, again by 6 turnover of cooling water outlet and inlet pipe.Reactor core solution top is a reactor core top reflector 7, and core vessel is outward water or graphite reflector 8.

Nuclear design starting condition: uranium-235 is loading amount 4.44kg just, and uranium-235 enrichment is 90%, UO ₂(NO ₃) ₂Aqueous solution contains 0.2mol/L nitric acid.Result of calculation K _EffSee Table 1, K with the variation of solution uranium concentration _EffThe corresponding uranium concentration of maximum point is 54gU/L, and the stack operation working point can be selected in 46gU/L, corresponding solution volume 111.8L.

The flat cylindrical reactor core of table 1 (not containing Gd-155) K _EffWith uranium concentration delta data table

Numbering	Uranium concentration gU/L in the solution	Solution height Hcm	Full rod withdrawal K eff	Uranium-235 loading amount Kg	Liquor capacity L
						7H7046F	46	32.00	1.000085	4.437	111.86
7H7048F	48	30.67	1.007643	4.437	107.17
						7H7050F	50	29.44	1.007942	4.439	102.91
7H7052F	52	28.31	1.009530	4.441	98.96
						7H7054F	54	27.26	1.009798	4.437	95.29
7H7056F	56	26.29	1.009109	4.439	91.90
						7H7058F	58	25.38	1.007536	4.440	88.71

Embodiment 2

As shown in Figure 1, adopt flat cylindrical core structure, add suitable flammable neutron poison Gd-155 in the reactor core solution (with Gd (NO ₃) ₃Form).

Core structure is with embodiment 1, just at UO ₂(NO ₃) ₂The middle gadolinium-155 that increases.Nuclear design calculation result K _EffSee Table 2, K with the variation of solution uranium concentration _EffThe corresponding uranium concentration of maximum point is 52gU/L, and the stack operation working point can be selected in 46gU/L, corresponding solution volume 122.3L, and the Gd-155 amount is 9.13 grams.Full power is moved even burnup, K under 46gU/L concentration _EffSee Table 3 with the burnup variation.

The flat cylindrical reactor core of table 2 (containing Gd-155) K _EffWith uranium concentration delta data table

Numbering	Uranium concentration gU/L in the solution	Solution height Hcm	Full rod withdrawal K eff	Uranium-235 loading amount Kg	Liquor capacity L	Full rod withdrawal K eff	Gd-155
								7H7042AGD	42	38.33	0.994550	4.85465	133.981	0.916138	9.13126
7H7044AGD	44	36.59	0.999497	4.85582	127.899	0.922527	9.13117
								7H7046AGD	46	35.00	1.002238	4.85311	122.341	0.926179	9.13111
7H7048AGD	48	33.54	1.004490	4.85388	117.238	0.929326	9.13099
								7H7050AGD	50	32.20	1.005608	4.85549	112.554	0.931801	9.13118
7H7052AGD	52	30.96	1.005958	4.85652	108.220	0.933199	9.13104
								7H7054AGD	54	29.81	1.004269	4.85227	104.200	0.933025	9.13111
7H7056AGD	56	28.75	1.003107	4.85471	100.495	0.931284	9.13102
								7H7058AGD	58	27.76	1.001679	4.85649	97.0340	0.931943	9.13101

The flat cylindrical reactor core of table 3 (containing Gd-155) K _EffWith burnup delta data table

EFPD	Full rod withdrawal K eff	Gd-155
			0	1.0022	9.13111
2	1.0022	9.11097
			100	1.0018	8.19998
200	1.0016	7.69303
			300	1.0015	7.22290
400	1.0017	6.78037
			500	1.0018	6.36390
600	1.0019	5.97260
			700	1.0018	5.60332
800	1.0018	5.25653
			900	1.0021	4.93042
1000	1.0019	4.62379

Embodiment 3

As shown in Figure 2, cylindrical core structure at the bottom of the dish does not contain flammable neutron poison Gd-155 in the reactor core solution.

Core structure is substantially with embodiment 1, just reactor core is gone to the bottom by flat change dish at the bottom of, R is 630mm at the bottom of the dish, r is 63mm, the high 142mm of dish, dish volume are 33.70L.Reactor core solution height 21.4～30.5cm (becoming) with the solution uranium concentration, uranium-235 is loading amount 3.00kg just, and uranium-235 enrichment is 90%.Nuclear design calculation result K _EffSee Table 4, K with the variation of solution uranium concentration _EffThe corresponding uranium concentration of maximum point is 44gU/L, and the stack operation working point can be selected in 36gU/L, corresponding solution volume 95L.As realizing 100L, must strengthen core diameter.

Cylindrical reactor core K at the bottom of table 4 dish _EffWith uranium concentration delta data table (not containing Gd-155)

Numbering	Uranium concentration gU/L in the solution	Solution height Hcm	Full rod withdrawal K eff	Uranium-235 loading amount Kg	Liquor capacity L	The high cm of air cavity
							E7034	34	30.48	1.002913	2.9511	100.63	9.52
E7036	36	28.91	1.008228	2.9523	95.04	11.09
							E7038	38	27.50	1.011884	2.9518	90.02	12.50
E7040	40	26.24	1.014046	2.9511	85.54	13.76

E7042	42	25.09	1.015186	2.9510	81.44	14.91
							E7044	44	24.05	1.015231	2.9515	77.74	15.95
E7046	46	23.10	1.013889	2.9496	74.36	16.90
							E7048	48	22.23	1.012135	2.9503	71.26	17.77
E7050	50	21.43	1.009611	2.9512	68.41	18.57

Claims (5)

1. " homogeneous solution-type reactor " solution reaction heap with inherent safety is used the UO that concentrates ₂(NO ₃) ₂Solution or UO ₂SO ₄Solution is characterized in that as nuclear fuel: height/core diameter is than the pancaked core that is 0.3～0.8 to adopt reactor core solution, and when volumetric specific power maintained 2.0～2.5kW/L, the reactor core liquor capacity can reach 50～200L, and heap power is greater than 100kW.

2. " homogeneous solution-type reactor " solution reaction heap with inherent safety according to claim 1, it is characterized in that: described pancaked core is a cylindrical reactor core at the bottom of flat cylindrical reactor core or the dish, reactor core is divided into inside and outside two districts, and inner region does not have cooling tube, and outskirt is arranged cooling tube; No cooling tube inner region (1) is furnished with control rod guide tube (4), and control rod guide tube (4) and the loam cake of core vessel (2) and the seal welding of going to the bottom of core vessel (2) are chilled water in the control rod guide tube (4), contact with fuel solution outward; Reactor core solution radially outskirt is furnished with cooling tube fuel inner region (3), and the cooling tube curl vertically coils, and cooling tube water is flowed to cooling tube collecting pipe (5), is passed in and out by cooling water outlet and inlet pipe (6) again; Reactor core solution top is provided with reactor core top reflector (7), and core vessel is provided with water or graphite reflector (8) outward.

3. " homogeneous solution-type reactor " solution reaction heap with inherent safety according to claim 1 and 2 is characterized in that: be added with flammable neutron poison Gd-155 in the reactor core solution.

4. " homogeneous solution-type reactor " solution reaction heap with inherent safety according to claim 3, it is characterized in that: flammable neutron poison Gd-155 is Gd (NO ₃) ₃Form.

5. " homogeneous solution-type reactor " solution reaction heap with inherent safety according to claim 3 is characterized in that: adopt the mode that becomes solution uranium concentration and the operation of change power to move.

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