摘要:
A method for mitigating crack growth on the surface of stainless steel or other metal components in a water-cooled nuclear reactor. A compound containing a noble metal, e.g., palladium, is injected into the water of the reactor in the form of a solution or suspension. This compound has the property that it decomposes under reactor thermal conditions to release ions/atoms of the noble metal which incorporate in or deposit on the interior surfaces of the crack. The compound may be organic, organometallic (e.g., palladium acetylacetonate) or inorganic in nature. The palladium deposited inside a crack should exhibit catalytic behavior even if the bulk surface palladium is depleted under high fluid flow conditions. As a result, the electrochemical potential inside the crack is decreased to a level below the critical potential to protect against intergranular stress corrosion cracking.
摘要:
A method for ensuring the distribution of noble metal in the reactor circuit during plant application without measuring the reactor water for noble metal content by chemical analysis. The method involves the measurement of electrochemical corrosion potential in an autoclave or a high-flow test section that is connected to the reactor water circuit through sample lines downstream of the injection port, preferably the point in the reactor circuit which is furthest from the injection port. If the noble metal flows into the autoclave or test section at these distant points in the reactor circuit, then the noble metal will deposit on the test specimens inside the autoclave or test section. After the noble metal has been injected for a predetermined duration, the electrochemical corrosion potential autoclave or test section is exposed to hydrogen water chemistry conditions and the electrochemical corrosion potentials of the specimens inside the autoclave or test section will be measured to determine the extent of their catalytic response. A good catalytic response indicates that the noble metal has reached the locations upstream where electrochemical corrosion potential is being measured.
摘要:
A device for generating direct current by neutron activation of a plurality of series-connected beta-emitter (nuclear decay electron) cells, located in the out-of-core region of a light water nuclear reactor. The device can be used as either a current source, or preferably configured as a DC voltage source, capable of powering low-power, radiation-hardened, high-temperature integrated circuitry contained in the reactor vessel. As such, the device acts like a DC battery that is activated by (n, .gamma.) reactions, both thermal and epithermal (by resonance capture). The device is not operable until exposed to a substantial neutron flux, so it has unlimited shelf-life and is not radioactive during manufacture In the preferred embodiment, an isotope of the metallic rare-earth element dysprosium is configured in a "sandwich" geometry to generate sufficient current that a useful steady voltage can be generated by means of a simple voltage regulation circuit.
摘要:
An improved nuclear fuel element is disclosed for use in the core of nuclear reactors. The improved nuclear fuel element has a composite cladding of an outer portion forming a substrate having on the inside surface a metal layer selected from the group consisting of copper, nickel, iron and alloys of the foregoing with a gap between the composite cladding and the core of nuclear fuel. The nuclear fuel element comprises a container of the elongated composite cladding, a central core of a body of nuclear fuel material disposed in and partially filling the container and forming an internal cavity in the container, an enclosure integrally secured and sealed at each end of said container and a nuclear fuel material retaining means positioned in the cavity. The metal layer of the composite cladding prevents perforations or failures in the cladding substrate from stress corrosion cracking or from fuel pellet-cladding interaction or both. The substrate of the composite cladding is selected from conventional cladding materials and preferably is a zirconium alloy.
摘要:
A novel aqueous electrolytic activating solution and a method for electroplating zirconium and zirconium alloys are disclosed. The novel aqueous electrolytic activating solution is comprised of from about 10 to about 20 grams per liter of ammonium bifluoride (NH.sub.4 FHF) and from about 0.75 to 2 grams per liter of sulfuric acid (H.sub.2 SO.sub.4).
摘要翻译:公开了一种新型的水性电解活化溶液和电镀锆锆合金的方法。 新型含水电解活化溶液由约10至约20克/升氟化氢铵(NH 4 FHF)和约0.75至2克/升硫酸(H 2 SO 4)组成。
摘要:
In a boiling water reactor nuclear plant, hydrogen is injected into the feed water to neutralize radiolysis which causes stress corrosion in stainless steel components. It has been discovered that by inhibiting volatile ammonia, and other gaseous nitrogen compounds from leaving the liquid phase portions of the plant to the steam phase portions of the plant, radiation is reduced to acceptable levels. Formation of ammonia is inhibited chemically, by altering the reaction paths for volatile nitrogen species with trace additives in the parts per billion range, suitable additives include nitrous oxide, copper, zinc, carbon dioxide, and other components. It has also been found that by manipulating the pH, the formation of the voltage nitrogen compounds, especially ammonia, is decreased. Similarly, by physically altering plant operating conditions to reduce sparging or scrubbing of the gases from areas of high radiation, confinement of the N-16 within the liquid phase of the plant within the reactor vessel occurs. It is further found that by decreasing the total hydrogen concentration in the core region, the N-16 volatility can be limited. This includes alternate hydrogen injection points and enhancement of the hydrogen-oxygen recombination reaction by e.g., catalysis by radiation or by surfaces. The possibility of increasing the N-16 holdup time in the steam phase is also considered. Finally, the concept of operating at a higher electrochemical potential which requires a lower hydrogen concentration and hence less N-16 converted to the volatile form is also described.
摘要:
An improved nuclear fuel element is disclosed for use in the core of nuclear reactors. The improved nuclear fuel has a composite cladding container comprising an outer layer having two coatings on the inside surface with the first coating on the outer layer being a diffusion barrier and the second coating on the first coating being a metal layer. The diffusion barrier is comprised of chromium or a chromium alloy, and the metal layer is selected from the group consisting of copper, nickel, iron and alloys thereof. The nuclear fuel element comprises a container of the elongated composite cladding, a central core of a body of nuclear fuel material disposed in and partially filling the container and forming an internal cavity in the container, an enclosure integrally secured and sealed at each end of said container and a nuclear fuel material retaining means positioned in the cavity. The metal layer and the diffusion barrier of the composite cladding prevent perforations or failures in the outer layer of the cladding from stress corrosion cracking or from fuel pellet-cladding interaction or both. The outer layer of the composite cladding is selected from conventional cladding materials and preferably is a zirconium alloy.
摘要:
An improved nuclear fuel element is disclosed for use in the core of nuclear reactors. The improved nuclear fuel element has a metal liner and a diffusion barrier disposed between the cladding and the nuclear fuel material. The diffusion barrier is in the form of a metal coating with the diffusion barrier being coated on the internal surface of the cladding in one embodiment and the diffusion barrier being coated on the outside surface of the metal liner in another embodiment. The diffusion barrier is a coating of chromium or a chromium alloy and serves to prevent any alloying or formation of low melting eutectic liquid phases between the metal liner and the cladding at elevated temperatures. The metal liner is selected from the group consisting of stainless steel, copper, copper alloys, nickel, and nickel alloys.
摘要:
A passive catalytic ammonia converter operating in the water/steam mixture exiting the core of a boiling water reactor. The catalytic ammonia converter is made of catalytic material arranged and situated such that substantially all of the water/steam mixture entering the water/steam separator device flows over the surface of the catalytic material. The catalytic surfaces react ammonia and/or NO with O.sub.2 or H.sub.2 O.sub.2 in the water/steam mixture to form nitrite or nitrate. The passive catalytic ammonia converter is constructed to ensure that the pressure drop of the reactor water across the device is very small. The catalytic ammonia converter can include a plurality of stainless steel flow-through housings packed with catalytic ammonia converter material, which could take the form of tangled wire or strips, crimped ribbon, porous sintered metal composite or any other structure having a high surface area-to-volume ratio.
摘要翻译:一种被动催化氨转化器,其工作在离开沸水反应堆核心的水/蒸汽混合物中。 催化氨转化器由催化材料制成,催化材料布置和定位,使得进入水/蒸汽分离器装置的基本上所有的水/蒸汽混合物流过催化材料的表面。 催化剂表面在水/蒸汽混合物中将氨和/或NO与O 2或H 2 O 2反应形成亚硝酸盐或硝酸盐。 被动催化氨转化器被构造成确保反应器水在整个装置上的压降非常小。 催化氨转化器可以包括多个不锈钢流通壳体,其中填充有催化氨转化器材料,其可以采取缠结线或条带,卷曲带,多孔烧结金属复合材料或具有高表面积的任何其它结构的形式, 体积比。
摘要:
A method and an apparatus for measuring the degree of intergranular stress corrosion cracking protection in the area of the core shroud weldments. Electrochemical potential sensors are attached to the shroud wall and the upper core spray line at locations near the actual weld surface of concern to ensure the accuracy of the electrochemical potential measurements. A working electrode doped or coated with noble metal and a reference electrode are implanted into the reactor core shroud. A throughhole is drilled or machined into the shroud wall at an elevation just below the top guide support ring, i.e., near the core shroud weldments. Then a plug containing the working and reference electrodes is inserted into the throughhole.