CA2353724A1 - Method for controlling zinc addition to power reactor - Google Patents
Method for controlling zinc addition to power reactor Download PDFInfo
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- CA2353724A1 CA2353724A1 CA002353724A CA2353724A CA2353724A1 CA 2353724 A1 CA2353724 A1 CA 2353724A1 CA 002353724 A CA002353724 A CA 002353724A CA 2353724 A CA2353724 A CA 2353724A CA 2353724 A1 CA2353724 A1 CA 2353724A1
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- Prior art keywords
- zinc
- ppb
- concentration
- reactor
- equation
- Prior art date
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- 239000011701 zinc Substances 0.000 title claims abstract description 170
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 title claims abstract description 132
- 229910052725 zinc Inorganic materials 0.000 title claims abstract description 132
- 238000000034 method Methods 0.000 title claims abstract description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 48
- PTFCDOFLOPIGGS-UHFFFAOYSA-N Zinc dication Chemical compound [Zn+2] PTFCDOFLOPIGGS-UHFFFAOYSA-N 0.000 claims abstract description 18
- 230000005855 radiation Effects 0.000 claims abstract description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 32
- 238000009835 boiling Methods 0.000 claims description 15
- 238000010348 incorporation Methods 0.000 claims description 15
- 230000008021 deposition Effects 0.000 claims description 13
- 229910052742 iron Inorganic materials 0.000 claims description 13
- 238000009825 accumulation Methods 0.000 claims description 11
- 238000005260 corrosion Methods 0.000 claims description 10
- 230000007797 corrosion Effects 0.000 claims description 10
- 239000000446 fuel Substances 0.000 claims description 5
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 238000005253 cladding Methods 0.000 claims description 3
- 230000026676 system process Effects 0.000 claims 1
- 230000008569 process Effects 0.000 abstract description 4
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical class [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 11
- 239000011787 zinc oxide Chemical class 0.000 description 5
- 229910017052 cobalt Inorganic materials 0.000 description 3
- 239000010941 cobalt Substances 0.000 description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- 230000002285 radioactive effect Effects 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000012857 radioactive material Substances 0.000 description 2
- 239000000941 radioactive substance Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 150000003751 zinc Chemical class 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229910001347 Stellite Inorganic materials 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000007900 aqueous suspension Substances 0.000 description 1
- AHICWQREWHDHHF-UHFFFAOYSA-N chromium;cobalt;iron;manganese;methane;molybdenum;nickel;silicon;tungsten Chemical compound C.[Si].[Cr].[Mn].[Fe].[Co].[Ni].[Mo].[W] AHICWQREWHDHHF-UHFFFAOYSA-N 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910001026 inconel Inorganic materials 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 229940112824 paste Drugs 0.000 description 1
- 239000006072 paste Substances 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- -1 stainless steel Chemical compound 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229940052228 zinc oxide paste Drugs 0.000 description 1
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C17/00—Monitoring; Testing ; Maintaining
- G21C17/02—Devices or arrangements for monitoring coolant or moderator
- G21C17/022—Devices or arrangements for monitoring coolant or moderator for monitoring liquid coolants or moderators
- G21C17/0225—Chemical surface treatment, e.g. corrosion
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C9/00—Emergency protection arrangements structurally associated with the reactor, e.g. safety valves provided with pressure equalisation devices
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C19/00—Arrangements for treating, for handling, or for facilitating the handling of, fuel or other materials which are used within the reactor, e.g. within its pressure vessel
- G21C19/28—Arrangements for introducing fluent material into the reactor core; Arrangements for removing fluent material from the reactor core
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Monitoring And Testing Of Nuclear Reactors (AREA)
- Control Of Non-Electrical Variables (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
- Treatment Of Water By Oxidation Or Reduction (AREA)
Abstract
Method for controlling the introduction of zinc to a nuclear power reactor t o control radiation build-up wherein zinc ions are introduced into the reactor water to counteract loss of zinc within the reactor system. In the process, the rate of introduction of zinc ions into the reactor water is balanced wit h the rate at which zinc ions are lost from the reactor.
Description
METHOD FOR CONTROLLING ZINC ADDITION TO
POWER REACTOR
The present application relates generally to reducing radiation build-up in nuclear power reactors. More particularly, the invention provides a method of controlling the concentration of zinc in the reactor water in order to counteract loss of zinc from the water to the reactor system.
BACKGROUND OF THE INVENTION
A major problem in water-cooled nuclear reactors is the accumulation of radioactive substances in the structural portions of the reactor system.
For example, during reactor shut-down, workers are exposed to radiation emanating from internal walls and tubing surfaces, and radioactive materials retained in oxide films which have accumulated on these surfaces are a major source of radiation exposure.
The build-up of radioactive cobalt (6°Co) in recircuiation piping of nuclear power reactors, including boiling water reactors, is a major source of radiation exposure, especially during reactor shutdown. Efforts have been made during recent years to identify parameters which affect the rate and magnitude of 6°Co buildup, with a view to developing methods for limiting the buildup. It has been shown in prior work that the majority of 6°Co buildup in recirculation piping occurs by incorporation of 6°Co into the oxide film during formation of the oxide film on stainle:>s steel surfaces.
U.S. Patent No. 4,950,449 describes the use of zinc ions to remove or lessen deposition of radioactive substances and reduce intergranular stress corrosion cracking in water-cooled nuclear reactors. The zinc may be added in the form of zinc oxide paste, slurry or aqueous ;solution.
SUBSTITUTE SHEET (RiJLE 26) U.S. Patent No. 4,756,$74 describes the use of zinc having a lower content of the 64Zn isotope in order to reduce accumulation of radioactive cobalt without increasing the presence of the 6jZ;n activation product of 64Zn.
The zinc in this form may be added to the reactor water in the form of a zinc salt or zinc oxide.
U.S. Patent No. 4,759,900 relates to the inhibition of deposition of radioactive cobalt by continuous injection of zinc' oxide into the reactor water.
The zinc oxide may be prepared in the form of a paste, slurry or aqueous solution.
A need exists for improvement in the control and monitoring of zinc addition to power reactors to better control the build-up of radioactive materials therein. The present invention seeks to satisfy that need.
SUMMARY OF THE INVENTION
It has been discovered, according to the present invention, that radiation build-L:p in a nuclear power reactor can be controlled by establishing in the water of the reactor a stable concentration of ionic zinc.
This permits beneficial mechanisms to reach and maintain a stable equilibrium.
According to one aspect, the present invf~ntion provides a method of controlling zinc addition to a nuclear power reaci:or to control radiation build-up wherein zinc ions are introduced into the reactor water, which comprises balancing the rate of introduction of zinc ions unto the reactor water with the rate at which zinc ions are lost to the reactor system.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described with reference to the accompanying drawings, in which:
POWER REACTOR
The present application relates generally to reducing radiation build-up in nuclear power reactors. More particularly, the invention provides a method of controlling the concentration of zinc in the reactor water in order to counteract loss of zinc from the water to the reactor system.
BACKGROUND OF THE INVENTION
A major problem in water-cooled nuclear reactors is the accumulation of radioactive substances in the structural portions of the reactor system.
For example, during reactor shut-down, workers are exposed to radiation emanating from internal walls and tubing surfaces, and radioactive materials retained in oxide films which have accumulated on these surfaces are a major source of radiation exposure.
The build-up of radioactive cobalt (6°Co) in recircuiation piping of nuclear power reactors, including boiling water reactors, is a major source of radiation exposure, especially during reactor shutdown. Efforts have been made during recent years to identify parameters which affect the rate and magnitude of 6°Co buildup, with a view to developing methods for limiting the buildup. It has been shown in prior work that the majority of 6°Co buildup in recirculation piping occurs by incorporation of 6°Co into the oxide film during formation of the oxide film on stainle:>s steel surfaces.
U.S. Patent No. 4,950,449 describes the use of zinc ions to remove or lessen deposition of radioactive substances and reduce intergranular stress corrosion cracking in water-cooled nuclear reactors. The zinc may be added in the form of zinc oxide paste, slurry or aqueous ;solution.
SUBSTITUTE SHEET (RiJLE 26) U.S. Patent No. 4,756,$74 describes the use of zinc having a lower content of the 64Zn isotope in order to reduce accumulation of radioactive cobalt without increasing the presence of the 6jZ;n activation product of 64Zn.
The zinc in this form may be added to the reactor water in the form of a zinc salt or zinc oxide.
U.S. Patent No. 4,759,900 relates to the inhibition of deposition of radioactive cobalt by continuous injection of zinc' oxide into the reactor water.
The zinc oxide may be prepared in the form of a paste, slurry or aqueous solution.
A need exists for improvement in the control and monitoring of zinc addition to power reactors to better control the build-up of radioactive materials therein. The present invention seeks to satisfy that need.
SUMMARY OF THE INVENTION
It has been discovered, according to the present invention, that radiation build-L:p in a nuclear power reactor can be controlled by establishing in the water of the reactor a stable concentration of ionic zinc.
This permits beneficial mechanisms to reach and maintain a stable equilibrium.
According to one aspect, the present invf~ntion provides a method of controlling zinc addition to a nuclear power reaci:or to control radiation build-up wherein zinc ions are introduced into the reactor water, which comprises balancing the rate of introduction of zinc ions unto the reactor water with the rate at which zinc ions are lost to the reactor system.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described with reference to the accompanying drawings, in which:
SU6STITUTE SHEET (RULE 26) Figure 1 is a simplified boiling water reacaor flowchart for zinc mass balance; and Figure 2 is a plot showing a comparison o~f the empirical equation for zinc concentration factor (CF) and actual plant data.
DETAILED DESCRIPTION OF THE INVENTION
The basis of the zinc addition process of the present invention is that a stable concentration of ionic zinc is established and maintained in the reactor water to permit the beneficial mechanisms pertaining to the control of radiation build-up to reach and maintain an equilibrium. It has been determined according to the present invention that the higher the concentration of ionic zinc, the better are the results in terms of reduction of 6pC0 build-up. To achieve this equilibrium; it is necessary to approximate the zinc loss mechanisms which must be balanced against the zinc input so that the radiation build-up prevention process remains stable. This zinc material balance has been developed and subsequently improved by using plant operating data to determine empirical coefficients.
The fundamental mass balance equation is Zinc In = Zinc Out + Zinc Accumulation (1) {a) Zinc In The amount of zinc entering the reactor is the sum total of the soluble and insoluble zinc concentration in the final feedvrater multiplied by the final feedwater flow rate:
Zinc In = F x {Zn~~ +ZnF1 ) where:
SUBSTITUTE SHEET (RULE 26) i WO 01!27933 PCT/L1S99l23588 F - Feedwater flow rate (M# /hr) ZnFs - Soluble zinc concentration in t:he feedwater (ppb) ZnFt = Insoluble zinc concentration in the feedwater (ppb) (b) Zinc Out The amount of zinc leaving the reactor consists of the zinc removed by the reactor water cleanup (RWCU) system and the zinc carried over in the stream.
Zinc Out = R x (((Znr~ +Znn, ) - (ZnrE~ +ZnREi )} + (S x Zns) (3) where:
R - Reactor water clean up flow rate (M#
/hr) Zna, = Soluble zinc concentration in the reacaor water {ppb) ZnRi - Insoluble zinc concentration in the reactor water (ppb) ZnREs = Soluble zinc concentration in the RWCU
effluent (ppb) ZnaEi = Insoluble zinc concentration in the RWCU
effluent (ppb) S - Steam flow rate (M#/hr) Zns - Total zinc concentration in the steam (ppb) SUBSTITUTE SHEET (RULE 26j The carryover of soluble species to the steam is generally accepted to be a factor of 10-3 or less. As such, the amount of zinc lost to the steam is assumed to be trivial for the purposes of a mass balance.
(c) Zinc Accumulation The accumulation is defined as being a combination of the zinc which is incorporated with the particulate iron entering with the feedwater (most of which is deposited on the fuel cladding), the zinc which is deposited on the fuel cladding surface as a result of the boiling process, and the zinc which is incorporated into the oxide film forming on the primary system surfaces. The equations follow:
Zinc Accumulation = (Zinc to Particulate)+(Zinc To Boiling (4) Deposition) +(Zinc To Corrosion Film Incorporation) It is necessary to break the above equation into its component parts to assess the key factors for each. First, evaluating the particulate incorporation:
Zinc To Particulate = F x {FeFs +FeFi) x (a x Znas ) {5) where:
FeFs - Soluble iron concentration in the feed water (ppb) FeFl - Insoluble iron concentration in the feedwater (ppb) a - Incorporation fraction for zinc (# Zn/# Fe/ppb of zinc) SUBSTITUTE SHEET (RULE 26) i~
Znr~s - Soluble zinc concentration in the reactor water (PPb) S - Steam flow rate (M# /hr) Zns -- Total zinc concentration in the steam (ppb) Second, is an evaluation of the boiling deposition:
Zinc to Bailing Deposition = F x (b x Znas',~ (6) where:
b = Boiling deposition fraction for zinc (# Zn/# I-~z0/ppb of zinc) Third, the incorporation of zinc into they corrosion films on system surfaces is extremely complex and is formulated as follows:
Zinc to Corrosion Film Incorporation = (c x: Zntts) x /C~c~dt (7) where:
c - corrosion incorporation fraction for zinc (# Zn/# Oxide/ppb of Zn) C~t~ - Oxide formation rate as function of time (# Oxide/hr) t - time (hr) The value of "c" is almost certain to be diffE~rent for each material which incorporates zinc (i.e., stainless steel, Inconel, Stellite, etc.). The corrosion for each material is logarithmic in nature but will have different magnitudes, and will vary as a function of environment (e.g. NWC vs. HWC). Consequently SUBSTITUTE SHEET (RIJLE 26) WO 01127933 PCT/US99/235$$
this part of the zinc consumption is extremely difficult, if not impossible, to determine when the surfaces are fresh. However, after the first several months of zinc addition, this consumption effect becomes negligible compared to the others and can be ignored.
Zinc ions are typically introduced at a rate to produce a zinc ion concentration of about 1 parts per billion (ppb) to 100 ppb. More typically, the zinc ion concentration is about 1 ppb to about. 50 ppb.
The zinc is usually introduced by using a source of zinc oxide. For example, it is possible to add a zinc oxide aqueous suspension into the reactor feed water. Alternatively, it is possible to use a side-stream to dissolve zinc ions from a bed of sintered oxide pellets. During stable operation, zinc is removed from the reactor water by RWCU and by adsorption into the particulate iron that enters the reactor water with. the feed water.
The temperature of the reactor water is typically in the range of 120 -550°F (BWR), 120 - 650°F (PWR}. The temperature is generally in the range of 212 - 350°F, more usually about 340° - 360°F.
The next step is to determine how much zinc will be required to maintain any given concentration in the reactor water. From the zinc balance approach developed above, an empirical equation has been developed which estimates the concentration factor for zinc between the reactor water and the feed water. This equation is as follows:
CF = 1 / {(0.9*RWCU}+(0.02~FeFw)+(0.008) f (g) where:
CF - Concentration Factor (R'xW Zn/FW Zn) 2S RWCU - Size of the reactor water cleanup system SUBSTITUTE SHEET (RULE 26) (% of FW flow) FeFw - Total iron concentration in the feedwater (ppb) In the above equation (8), 0.9 represents the efficiency of removal by the reactor water cleanup system, 0.02 represents the amount of zinc absorbed by the feedwater iron per ppb of zinc in the reactor water ("a" in Equation 5}, and .008 represents the boiling deposition factor for zinc ("b" in Equation 6).
This leads to a zinc consumption rate equation of Zn # /yr = t(ZnR*0.9*RWCU)+Znt~*0.02(*FeFw)+(ZnR*0.008)} *FW*(1E-9)*24*365 where:
Zn~z - Target reactor water zinc concentration (ppb) FW - Feedwater flow rate (lbs/hr}
The above equation yields the pounds of zinc required per year. In IS order to get the total pounds of Zn0 required, the answer must be divided by 0.8.
Figure 1 is a simplified boiling water reactor flow chart for the zinc mass balance developed according to the present invention. The zinc accumulation is shown as comprising zinc incorporation on non-fuel surfaces (2), zinc deposition on fuel surfaces by boiling (4) and zinc incorporation on particulate iron (6). Zinc is shown as entering the reactor (8) in the feed water stream to the reactor. The zinc leaves by way of t:he top (12) of the reactor by steam carryover to the turbine (14) and by way o~f the reactor water cleanup (RWCU) system (16).
DETAILED DESCRIPTION OF THE INVENTION
The basis of the zinc addition process of the present invention is that a stable concentration of ionic zinc is established and maintained in the reactor water to permit the beneficial mechanisms pertaining to the control of radiation build-up to reach and maintain an equilibrium. It has been determined according to the present invention that the higher the concentration of ionic zinc, the better are the results in terms of reduction of 6pC0 build-up. To achieve this equilibrium; it is necessary to approximate the zinc loss mechanisms which must be balanced against the zinc input so that the radiation build-up prevention process remains stable. This zinc material balance has been developed and subsequently improved by using plant operating data to determine empirical coefficients.
The fundamental mass balance equation is Zinc In = Zinc Out + Zinc Accumulation (1) {a) Zinc In The amount of zinc entering the reactor is the sum total of the soluble and insoluble zinc concentration in the final feedvrater multiplied by the final feedwater flow rate:
Zinc In = F x {Zn~~ +ZnF1 ) where:
SUBSTITUTE SHEET (RULE 26) i WO 01!27933 PCT/L1S99l23588 F - Feedwater flow rate (M# /hr) ZnFs - Soluble zinc concentration in t:he feedwater (ppb) ZnFt = Insoluble zinc concentration in the feedwater (ppb) (b) Zinc Out The amount of zinc leaving the reactor consists of the zinc removed by the reactor water cleanup (RWCU) system and the zinc carried over in the stream.
Zinc Out = R x (((Znr~ +Znn, ) - (ZnrE~ +ZnREi )} + (S x Zns) (3) where:
R - Reactor water clean up flow rate (M#
/hr) Zna, = Soluble zinc concentration in the reacaor water {ppb) ZnRi - Insoluble zinc concentration in the reactor water (ppb) ZnREs = Soluble zinc concentration in the RWCU
effluent (ppb) ZnaEi = Insoluble zinc concentration in the RWCU
effluent (ppb) S - Steam flow rate (M#/hr) Zns - Total zinc concentration in the steam (ppb) SUBSTITUTE SHEET (RULE 26j The carryover of soluble species to the steam is generally accepted to be a factor of 10-3 or less. As such, the amount of zinc lost to the steam is assumed to be trivial for the purposes of a mass balance.
(c) Zinc Accumulation The accumulation is defined as being a combination of the zinc which is incorporated with the particulate iron entering with the feedwater (most of which is deposited on the fuel cladding), the zinc which is deposited on the fuel cladding surface as a result of the boiling process, and the zinc which is incorporated into the oxide film forming on the primary system surfaces. The equations follow:
Zinc Accumulation = (Zinc to Particulate)+(Zinc To Boiling (4) Deposition) +(Zinc To Corrosion Film Incorporation) It is necessary to break the above equation into its component parts to assess the key factors for each. First, evaluating the particulate incorporation:
Zinc To Particulate = F x {FeFs +FeFi) x (a x Znas ) {5) where:
FeFs - Soluble iron concentration in the feed water (ppb) FeFl - Insoluble iron concentration in the feedwater (ppb) a - Incorporation fraction for zinc (# Zn/# Fe/ppb of zinc) SUBSTITUTE SHEET (RULE 26) i~
Znr~s - Soluble zinc concentration in the reactor water (PPb) S - Steam flow rate (M# /hr) Zns -- Total zinc concentration in the steam (ppb) Second, is an evaluation of the boiling deposition:
Zinc to Bailing Deposition = F x (b x Znas',~ (6) where:
b = Boiling deposition fraction for zinc (# Zn/# I-~z0/ppb of zinc) Third, the incorporation of zinc into they corrosion films on system surfaces is extremely complex and is formulated as follows:
Zinc to Corrosion Film Incorporation = (c x: Zntts) x /C~c~dt (7) where:
c - corrosion incorporation fraction for zinc (# Zn/# Oxide/ppb of Zn) C~t~ - Oxide formation rate as function of time (# Oxide/hr) t - time (hr) The value of "c" is almost certain to be diffE~rent for each material which incorporates zinc (i.e., stainless steel, Inconel, Stellite, etc.). The corrosion for each material is logarithmic in nature but will have different magnitudes, and will vary as a function of environment (e.g. NWC vs. HWC). Consequently SUBSTITUTE SHEET (RIJLE 26) WO 01127933 PCT/US99/235$$
this part of the zinc consumption is extremely difficult, if not impossible, to determine when the surfaces are fresh. However, after the first several months of zinc addition, this consumption effect becomes negligible compared to the others and can be ignored.
Zinc ions are typically introduced at a rate to produce a zinc ion concentration of about 1 parts per billion (ppb) to 100 ppb. More typically, the zinc ion concentration is about 1 ppb to about. 50 ppb.
The zinc is usually introduced by using a source of zinc oxide. For example, it is possible to add a zinc oxide aqueous suspension into the reactor feed water. Alternatively, it is possible to use a side-stream to dissolve zinc ions from a bed of sintered oxide pellets. During stable operation, zinc is removed from the reactor water by RWCU and by adsorption into the particulate iron that enters the reactor water with. the feed water.
The temperature of the reactor water is typically in the range of 120 -550°F (BWR), 120 - 650°F (PWR}. The temperature is generally in the range of 212 - 350°F, more usually about 340° - 360°F.
The next step is to determine how much zinc will be required to maintain any given concentration in the reactor water. From the zinc balance approach developed above, an empirical equation has been developed which estimates the concentration factor for zinc between the reactor water and the feed water. This equation is as follows:
CF = 1 / {(0.9*RWCU}+(0.02~FeFw)+(0.008) f (g) where:
CF - Concentration Factor (R'xW Zn/FW Zn) 2S RWCU - Size of the reactor water cleanup system SUBSTITUTE SHEET (RULE 26) (% of FW flow) FeFw - Total iron concentration in the feedwater (ppb) In the above equation (8), 0.9 represents the efficiency of removal by the reactor water cleanup system, 0.02 represents the amount of zinc absorbed by the feedwater iron per ppb of zinc in the reactor water ("a" in Equation 5}, and .008 represents the boiling deposition factor for zinc ("b" in Equation 6).
This leads to a zinc consumption rate equation of Zn # /yr = t(ZnR*0.9*RWCU)+Znt~*0.02(*FeFw)+(ZnR*0.008)} *FW*(1E-9)*24*365 where:
Zn~z - Target reactor water zinc concentration (ppb) FW - Feedwater flow rate (lbs/hr}
The above equation yields the pounds of zinc required per year. In IS order to get the total pounds of Zn0 required, the answer must be divided by 0.8.
Figure 1 is a simplified boiling water reactor flow chart for the zinc mass balance developed according to the present invention. The zinc accumulation is shown as comprising zinc incorporation on non-fuel surfaces (2), zinc deposition on fuel surfaces by boiling (4) and zinc incorporation on particulate iron (6). Zinc is shown as entering the reactor (8) in the feed water stream to the reactor. The zinc leaves by way of t:he top (12) of the reactor by steam carryover to the turbine (14) and by way o~f the reactor water cleanup (RWCU) system (16).
SUBSTITUTE SHEET (RULE 26) WO 01127933 PCT/LTS99f23588 Figure 2 shows a plot of the empirical. concentration factor (CF) equation. The blackened squares are actual plant data and the blackened rectangles are obtained from the equations. It can be seen from Figure 2 that a reasonably good fit exists as between the two sets of data.
EXAMPLE
The following example illustrates the present invention.
Assuming a specific plant averaged 2.5 ppb total iron in the feedwater, a zinc concentration factor approximately 20 woL~ld be expected. At a target reactor water zinc concentration of 10 ppb, the feedwater zinc concentration would need to be 0.5 ppi~. For a feedwater flaw of 10 million lbs/hr with a 1% cleanup system, the equation calculates that 41.2 lbs/yr of zinc (assuming full power operation all year) would be required,, or 51.5 lbs/yr (23.4 kg/yr) of zinc oxide.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to .cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
EXAMPLE
The following example illustrates the present invention.
Assuming a specific plant averaged 2.5 ppb total iron in the feedwater, a zinc concentration factor approximately 20 woL~ld be expected. At a target reactor water zinc concentration of 10 ppb, the feedwater zinc concentration would need to be 0.5 ppi~. For a feedwater flaw of 10 million lbs/hr with a 1% cleanup system, the equation calculates that 41.2 lbs/yr of zinc (assuming full power operation all year) would be required,, or 51.5 lbs/yr (23.4 kg/yr) of zinc oxide.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to .cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
SUBSTITUTE SHEET (RIFLE 26)
Claims (13)
1. A method of controlling zinc addition to a nuclear power reactor to control radiation build-up wherein zinc ions are introduced into the reactor water, which comprises balancing the rate of introduction of zinc ions into the reactor water with the rate at which zinc ions are lost to the reactor system.
2. A method according to claim 1, wherein the zinc ions are introduced to produce a zinc ion concentration of about 1 ppb to 100 ppb.
3. A method according to claim 2, wherein the zinc ion concentration is about 1 ppb to 50 ppb.
4. A method according to claim 1, wherein the zinc ions are introduced according to the equation:
Zinc In = Zinc Out + Zinc Accumulation wherein zinc in is the amount of zinc entering the reactor water, zinc out is the amount of zinc lost to system processes, and zinc accumulation is combination of the zinc which is incorporated with particulate iron entering with feedwater, zinc which is deposited on the fuel cladding surface as a result of boiling, and zinc which is incorporated into oxide film which forms on surfaces of the reactor and components thereof.
Zinc In = Zinc Out + Zinc Accumulation wherein zinc in is the amount of zinc entering the reactor water, zinc out is the amount of zinc lost to system processes, and zinc accumulation is combination of the zinc which is incorporated with particulate iron entering with feedwater, zinc which is deposited on the fuel cladding surface as a result of boiling, and zinc which is incorporated into oxide film which forms on surfaces of the reactor and components thereof.
5. A method according to claim 4, wherein zinc in is defined by the equation:
Zinc In = F x (Zn Fs +Zn F1) where:
F = Feedwater flow rate (M# /hr) Zn Fs - Soluble zinc concentration in the feedwater (ppb) Zn FI = Insoluble zinc concentration in the feedwater (ppb).
Zinc In = F x (Zn Fs +Zn F1) where:
F = Feedwater flow rate (M# /hr) Zn Fs - Soluble zinc concentration in the feedwater (ppb) Zn FI = Insoluble zinc concentration in the feedwater (ppb).
6. A method according to claim 5, wherein zinc out is defined by the equation:
Zinc Out = R X [((Zn R5+Zn R1)-(Zn REs +Zn REi)]+(S x Zn s) (3) where:
R = Reactor water clean up flow rate (M#/hr) Zn R5 = Soluble zinc concentration in the reactor water (ppb) Zn R1 - Insoluble zinc concentration in the reactor water (ppb) Zn REs = Soluble zinc concentration in the RWCU effluent (ppb) Zn RE1 = Insoluble zinc concentration in the RWCU
effluent (ppb) S = Steam flow rate (M#/hr) Zn s - Total zinc concentration in the steam (ppb)
Zinc Out = R X [((Zn R5+Zn R1)-(Zn REs +Zn REi)]+(S x Zn s) (3) where:
R = Reactor water clean up flow rate (M#/hr) Zn R5 = Soluble zinc concentration in the reactor water (ppb) Zn R1 - Insoluble zinc concentration in the reactor water (ppb) Zn REs = Soluble zinc concentration in the RWCU effluent (ppb) Zn RE1 = Insoluble zinc concentration in the RWCU
effluent (ppb) S = Steam flow rate (M#/hr) Zn s - Total zinc concentration in the steam (ppb)
7. A method according to claim 6, wherein zinc accumulation is defined by the equation:
Zinc Accumulation = (Zinc to Particulate)+(Zinc To Boiling (4) Deposition) +(Zinc To Corrosion Film Incorporation)
Zinc Accumulation = (Zinc to Particulate)+(Zinc To Boiling (4) Deposition) +(Zinc To Corrosion Film Incorporation)
8. A method according to claim 7, wherein zinc to particulate incorporation is defined by the equation:
Zinc To Particulate = F x (Fe F5+Fe F1)x(a x Zn R5) (5) where:
Fe F5 = Soluble iron concentration in the feed water (ppb) Fe F1 = Insoluble iron concentration in the feedwater (ppb) a = Incorporation fraction for zinc (# Zn/# Fe/ppb of zinc) Zn R5 = Soluble zinc concentration in the reactor water (ppb) S = Steam flow rate (M# /hr) Zns = Total zinc concentration in the steam (ppb).
Zinc To Particulate = F x (Fe F5+Fe F1)x(a x Zn R5) (5) where:
Fe F5 = Soluble iron concentration in the feed water (ppb) Fe F1 = Insoluble iron concentration in the feedwater (ppb) a = Incorporation fraction for zinc (# Zn/# Fe/ppb of zinc) Zn R5 = Soluble zinc concentration in the reactor water (ppb) S = Steam flow rate (M# /hr) Zns = Total zinc concentration in the steam (ppb).
9. A method according to claim 8, wherein zinc to boiling deposition is defined by the equation:
Zinc to Boiling Deposition = F x (b x Zn Rs) (6) where:
b = Boiling deposition fraction for zinc (# Zn/# H2O/ppb of zinc)
Zinc to Boiling Deposition = F x (b x Zn Rs) (6) where:
b = Boiling deposition fraction for zinc (# Zn/# H2O/ppb of zinc)
10. A method according to claim 9, wherein zinc to corrosion film incorporation is defined by the equation:
Zinc to Corrosion Film Incorporation = (c x Zn Rs) x /C(t)dt (7) where:
c = corrosion incorporation fraction for zinc (# Zn/# Oxide/ppb of Zn) C(t) = Oxide formation rate as function of time (# Oxide/hr) t = time (hr)
Zinc to Corrosion Film Incorporation = (c x Zn Rs) x /C(t)dt (7) where:
c = corrosion incorporation fraction for zinc (# Zn/# Oxide/ppb of Zn) C(t) = Oxide formation rate as function of time (# Oxide/hr) t = time (hr)
11. A method for estimating the concentration factor for zinc between the reactor water and the feed water of a nuclear reactor comprising using the equation:
CF = 1/{(0.9*RWCU)+(0.02*Fe FW)+(0.008)} (8) where:
CF = Concentration Factor (RxW Zn/FW
Zn) RWCU = Size of the reactor water cleanup system (% of FW flow) Fe Fw = Total iron concentration in the feedwater (ppb) wherein 0.9 represents the efficiency of removal by the reactor water cleanup system, 0.02 represents the amount of zinc absorbed by the feedwater iron per ppb of zinc in the reactor water, and 0.008 represents the boiling deposition factor for zinc.
CF = 1/{(0.9*RWCU)+(0.02*Fe FW)+(0.008)} (8) where:
CF = Concentration Factor (RxW Zn/FW
Zn) RWCU = Size of the reactor water cleanup system (% of FW flow) Fe Fw = Total iron concentration in the feedwater (ppb) wherein 0.9 represents the efficiency of removal by the reactor water cleanup system, 0.02 represents the amount of zinc absorbed by the feedwater iron per ppb of zinc in the reactor water, and 0.008 represents the boiling deposition factor for zinc.
12. A method according to claim 11, wherein the consumption rate of zinc is defined by the equation:
Zn #/yr = ~(Zn R*0.9*RWCU)+Zn R*0.02(*Fe Fw)+(Zn R*0.008)~
*FW*(1E-9)*24*365 where:
Zn R = Target reactor water zinc concentration (ppb) FW = Feedwater flow rate (lbs/hr)
Zn #/yr = ~(Zn R*0.9*RWCU)+Zn R*0.02(*Fe Fw)+(Zn R*0.008)~
*FW*(1E-9)*24*365 where:
Zn R = Target reactor water zinc concentration (ppb) FW = Feedwater flow rate (lbs/hr)
13. A method according to claim 12, wherein the total pounds of ZnO required is obtained by dividing the answer obtained according to the equation as defined in claim 14 by 0.8.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/US1999/023588 WO2001027933A1 (en) | 1999-10-08 | 1999-10-08 | Method for controlling zinc addition to power reactor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2353724A1 true CA2353724A1 (en) | 2001-04-19 |
Family
ID=22273781
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002353724A Abandoned CA2353724A1 (en) | 1999-10-08 | 1999-10-08 | Method for controlling zinc addition to power reactor |
Country Status (10)
| Country | Link |
|---|---|
| EP (1) | EP1149388A1 (en) |
| JP (1) | JP2002542458A (en) |
| KR (1) | KR20010108008A (en) |
| CN (1) | CN1313992A (en) |
| BG (1) | BG104498A (en) |
| BR (1) | BR9914624A (en) |
| CA (1) | CA2353724A1 (en) |
| CZ (1) | CZ20011865A3 (en) |
| HU (1) | HUP0104253A2 (en) |
| WO (1) | WO2001027933A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6937686B2 (en) * | 2002-09-30 | 2005-08-30 | General Electric Company | Iron control in BWR's with sacrificial electrodes |
| JP2008190933A (en) * | 2007-02-02 | 2008-08-21 | Japan Atom Power Co Ltd:The | Method for evaluating concentration of ion impurity in secondary coolant at pwr-type nuclear power plant and method for operating secondary cooling system at pwr-type nuclear power plant using such evaluation system |
| JP5118576B2 (en) * | 2008-08-12 | 2013-01-16 | 三菱重工業株式会社 | Operation method of nuclear power plant |
| CN104882184B (en) * | 2015-05-14 | 2017-03-29 | 华北电力大学 | The device and method of zincification in ADS reactor lead bismuth eutectic alloys |
| CN111681791B (en) * | 2020-06-16 | 2022-07-01 | 三门核电有限公司 | Nuclear power plant primary circuit zinc concentration control method |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4759900A (en) * | 1986-08-27 | 1988-07-26 | General Electric Company | Inhibition of radioactive cobalt deposition in water-cooled nuclear reactors |
| US5108697A (en) * | 1990-10-19 | 1992-04-28 | Westinghouse Electric Corp. | Inhibiting stress corrosion cracking in the primary coolant circuit of a nuclear reactor |
| JP3156113B2 (en) * | 1993-12-15 | 2001-04-16 | 株式会社日立製作所 | Water quality control method and device |
| JP3281213B2 (en) * | 1995-03-24 | 2002-05-13 | 株式会社東芝 | Water quality control method for boiling water reactor plant |
| DE19739361C1 (en) * | 1997-09-09 | 1998-10-15 | Siemens Ag | Zinc introduction into nuclear reactor primary water system |
-
1999
- 1999-10-08 WO PCT/US1999/023588 patent/WO2001027933A1/en not_active Application Discontinuation
- 1999-10-08 JP JP2000611741A patent/JP2002542458A/en active Pending
- 1999-10-08 KR KR1020017007121A patent/KR20010108008A/en not_active Application Discontinuation
- 1999-10-08 HU HU0104253A patent/HUP0104253A2/en unknown
- 1999-10-08 CA CA002353724A patent/CA2353724A1/en not_active Abandoned
- 1999-10-08 CN CN99801735A patent/CN1313992A/en active Pending
- 1999-10-08 EP EP99974115A patent/EP1149388A1/en not_active Withdrawn
- 1999-10-08 CZ CZ20011865A patent/CZ20011865A3/en unknown
- 1999-10-08 BR BR9914624-0A patent/BR9914624A/en not_active IP Right Cessation
-
2000
- 2000-06-02 BG BG104498A patent/BG104498A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| KR20010108008A (en) | 2001-12-07 |
| WO2001027933A1 (en) | 2001-04-19 |
| EP1149388A1 (en) | 2001-10-31 |
| BR9914624A (en) | 2001-10-16 |
| JP2002542458A (en) | 2002-12-10 |
| HUP0104253A2 (en) | 2002-03-28 |
| BG104498A (en) | 2001-05-31 |
| CN1313992A (en) | 2001-09-19 |
| CZ20011865A3 (en) | 2001-11-14 |
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