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EP0575420A1 - Procede de traitement de barres d'absorption de reacteurs nucleaires refroidis a l'eau - Google Patents

Procede de traitement de barres d'absorption de reacteurs nucleaires refroidis a l'eau

Info

Publication number
EP0575420A1
EP0575420A1 EP92906452A EP92906452A EP0575420A1 EP 0575420 A1 EP0575420 A1 EP 0575420A1 EP 92906452 A EP92906452 A EP 92906452A EP 92906452 A EP92906452 A EP 92906452A EP 0575420 A1 EP0575420 A1 EP 0575420A1
Authority
EP
European Patent Office
Prior art keywords
tritium
rods
melt
water
nuclear reactors
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP92906452A
Other languages
German (de)
English (en)
Inventor
Heinz Dworschak
Giovanni Modica
Francesco Mannone
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
European Atomic Energy Community Euratom
Original Assignee
European Atomic Energy Community Euratom
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by European Atomic Energy Community Euratom filed Critical European Atomic Energy Community Euratom
Publication of EP0575420A1 publication Critical patent/EP0575420A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • G21C19/34—Apparatus or processes for dismantling nuclear fuel, e.g. before reprocessing ; Apparatus or processes for dismantling strings of spent fuel elements
    • G21C19/38—Chemical means only
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/28—Treating solids
    • G21F9/30—Processing
    • G21F9/32—Processing by incineration
    • 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

Definitions

  • the invention relates to a method for processing absorber rods with regard to the compact and safe final storage of radioactive substances, these rods being designed as steel tubes filled with boron compounds.
  • the reactivity is checked using steel rods, e.g. of the type AISI 304 or 306, which are filled with boron compounds, in particular B.C (boron carbide).
  • steel rods e.g. of the type AISI 304 or 306, which are filled with boron compounds, in particular B.C (boron carbide).
  • the absorption properties for neutrons of the 1 0 B isotope are used. In interaction with thermal neutrons, this isotope forms 7 Li, which in turn interacts with fast neutrons and forms tritium 3 H.
  • tritium is referred to below as T and water containing tritium, in which some of the normal hydrogen atoms are replaced by tritium atoms, with HTO.
  • the isotope B itself also reacts with fast neutrons, whereby T is formed directly.
  • the following core reactions result:
  • a typical boiling water reactor contains 4140 rods, i.e. a total of 194 kg of boron carbide. After three years of use in a boiling water reactor, such a rod has a tritium budget of 0.85 Ci in addition to the radioactive activation products that usually occur when the metal is neutron bombarded. This tritium is largely in the boron carbide matrix. Approx. 6 per mille of the total amount of tritium is in the shell material of the rod and an even smaller fraction of about 0.2 per mille in the remaining gas space inside the rod.
  • the tritium thus formed can be bound within the structure in various ways:
  • these absorber rods cannot be used like a normal metallic radioactive waste product, e.g. be prepared for final storage by mechanical crushing and / or compacting.
  • the interaction with the neutrons makes the boron carbide embrittled, making it very fragile.
  • the container tubes have hairline cracks, which are caused on the one hand by the interactions of the boron carbide with the metallic material of the rods and on the other hand by the pressure generated due to the gases inside the tubes or finally by the boron carbide being deposited during neutron bombardment and the associated swelling caused in the rod.
  • waste disposal is particularly difficult due to the not negligible presence of the tritium.
  • the object of the invention is therefore to provide such a method, which leads to a waste product which can be disposed of significantly reduced volume.
  • this method is said to reduce the risk of an uncontrolled distribution of the radioactivity contained in the bars by not requiring mechanical treatment steps such as sawing.
  • a melt of iron is melted in a sintered aluminum oxide crucible in an electrically heated furnace.
  • the gas space above the melt is constantly flushed with an inert gas, for example argon.
  • the temperature of the melt is brought to at least 1500 ° C. and maintained.
  • the end of an absorption rod of the type specified above, which is to be worked up, is then introduced into the melt and is fed in according to the melting rate.
  • the melt is chosen so high that the shell material of the tube melts and the boron carbide can thus be exposed to the action of iron in the melt, a low-melting eutectic being formed.
  • the purging with argon prevents the boron from being oxidized, because boron oxide would be volatile at the temperature of the melt.
  • the melt is prepared in a zirconium oxide crucible located in an electromagnetic induction furnace.
  • the furnace consists of a quartz tube, which is surrounded by an induction coil and is connected at both ends to the flushing circuit.
  • the temperature of the melt is 1550 ° C. A few minutes after the rod to be melted has been introduced, a homogeneous mass is obtained which, after the furnace has cooled, results in a monolithic, compact material, the analysis of which is similar to that of Example 1.
  • nickel borides instead of iron, the same amount of nickel is used for the original melt. In this case arise predominantly nickel borides, but also iron and chromium borides or carbides.
  • the iron from the original melt is replaced by cobalt. This mainly results in cobalt borides and the usual Fe-Ni borides or carbides.
  • the rate at which the melt cools down after the rod has been inserted has little effect on the result, which was determined by comparing a rapid cooling caused by increased purge gas throughput in a few minutes with a natural cooling that took more than 12 hours.
  • crucible materials in particular graphite crucibles, are also more suitable, but also crucibles made of other metals with a high melting point, such as e.g. Ti, V, Zr, Mo, Hf, Ta, W, Pt, Pd, which are lined with an inner coating of 5 mm graphite or aluminum oxide or zirconium oxide.
  • integral absorber elements can also be disposed of, which consist of a central guide rod made of SS AISI 304 steel and double-walled sheets welded to it in a cross shape. Between these sheets are lined up next to each other in the longitudinal direction of the rod 15 of the absorber rods mentioned above. In order to be able to achieve a more favorable ratio between the material to be introduced into the furnace and the diameter of the furnace, it may be expedient to cut the sheets off the guide rod before melting. Due to the fact that the first rod usually contains no boron carbide next to the guide rod, the one with a suitable choice is

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Plasma & Fusion (AREA)
  • Environmental & Geological Engineering (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Catalysts (AREA)

Abstract

Selon un procédé de traitement de barres d'absorption constituées de tubes en acier remplis de composés de bore qui permet de stocker définitivement les substances radioactives de manière sûre dans un espace réduit, les barres sont immergées dans un bain en fusion composé de fer, nickel, chrome ou manganèse, dans une atmosphère exempte d'oxygène, et le bain est maintenu à une température supérieure à 1500 °C. Le tritium contenu dans les tubes est libéré et enlevé à l'aide d'un gaz inerte de lavage, puis lié dans un piège à tritium. On obtient ainsi un bloc monolithique exempt de tritium qui contient essentiellement des borures et des carbures métalliques et qui peut être stocké définitivement.
EP92906452A 1991-03-13 1992-03-10 Procede de traitement de barres d'absorption de reacteurs nucleaires refroidis a l'eau Withdrawn EP0575420A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
LU87907 1991-03-13
LU87907A LU87907A1 (de) 1991-03-13 1991-03-13 Verfahren zum aufarbeiten von absorberstaeben aus wassergekuehlten kernreaktoren

Publications (1)

Publication Number Publication Date
EP0575420A1 true EP0575420A1 (fr) 1993-12-29

Family

ID=19731283

Family Applications (2)

Application Number Title Priority Date Filing Date
EP92906452A Withdrawn EP0575420A1 (fr) 1991-03-13 1992-03-10 Procede de traitement de barres d'absorption de reacteurs nucleaires refroidis a l'eau
EP92104071A Withdrawn EP0503557A1 (fr) 1991-03-13 1992-03-10 Procédé de retraitement de barreaux absorbants provenant de réacteurs nucléaires refroidis à l'eau

Family Applications After (1)

Application Number Title Priority Date Filing Date
EP92104071A Withdrawn EP0503557A1 (fr) 1991-03-13 1992-03-10 Procédé de retraitement de barreaux absorbants provenant de réacteurs nucléaires refroidis à l'eau

Country Status (5)

Country Link
EP (2) EP0575420A1 (fr)
JP (1) JPH06505797A (fr)
CA (1) CA2105764A1 (fr)
LU (1) LU87907A1 (fr)
WO (1) WO1992016948A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9823046D0 (en) * 1998-10-22 1998-12-16 British Nuclear Fuels Plc Electrochemical dissolution
RU2231839C2 (ru) * 2001-10-25 2004-06-27 Федеральное государственное унитарное дочернее предприятие Электрогорский научно-исследовательский центр по безопасности атомных электростанций Всероссийского научно-исследовательского института по эксплуатации атомных электростанций Способ отверждения жидких радиоактивных отходов
CN114113188B (zh) * 2021-10-12 2023-03-03 四川大学 一种高效的氚分析方法、装置、设备和存储介质

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4417790A (en) * 1979-05-10 1983-11-29 American Optical Corporation Finished ophthalmic lens comprising an optical smooth coating over a rough-surfaced base
FR2583208B1 (fr) * 1985-06-07 1992-04-24 Commissariat Energie Atomique Procede et dispositif pour le traitement de dechets trities solides non organiques
DE3930420C1 (en) * 1989-09-12 1990-11-22 Bundesrepublik Deutschland, Vertreten Durch Den Bundesminister Der Verteidigung, Dieser Vertreten Durch Den Praesidenten Des Bundesamtes Fuer Wehrtechnik Und Beschaffung, 5400 Koblenz, De Radioactive waste tritium sepn. - by flushing in gas flow with oxygen, heating and passing tritium through water

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9216948A1 *

Also Published As

Publication number Publication date
EP0503557A1 (fr) 1992-09-16
LU87907A1 (de) 1992-11-16
WO1992016948A1 (fr) 1992-10-01
CA2105764A1 (fr) 1992-09-14
JPH06505797A (ja) 1994-06-30

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