EP0418722B1 - Total decontamination process for radioactive metal material - Google Patents

Total decontamination process for radioactive metal material Download PDF

Info

Publication number
EP0418722B1
EP0418722B1 EP90117571A EP90117571A EP0418722B1 EP 0418722 B1 EP0418722 B1 EP 0418722B1 EP 90117571 A EP90117571 A EP 90117571A EP 90117571 A EP90117571 A EP 90117571A EP 0418722 B1 EP0418722 B1 EP 0418722B1
Authority
EP
European Patent Office
Prior art keywords
tank
bath
water
washing
solution
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.)
Expired - Lifetime
Application number
EP90117571A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0418722A1 (en
Inventor
Fiorenzo Bregani
Antonio Garofalo
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.)
Enel SpA
Original Assignee
Enel SpA
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 Enel SpA filed Critical Enel SpA
Publication of EP0418722A1 publication Critical patent/EP0418722A1/en
Application granted granted Critical
Publication of EP0418722B1 publication Critical patent/EP0418722B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • G21F9/001—Decontamination of contaminated objects, apparatus, clothes, food; Preventing contamination thereof

Definitions

  • the prevent invention relates to a total decontamination process for radioactive metal material, in particular to radioactive metal material presenting big surfaces and recesses, like the tubes for the tube nests in the heat exchangers of a nuclear power station.
  • radioactive metal surfaces are decontaminated by means of chemical solutions, electrolytic processes, mechanical means, pressurized water jets and application of ultrasounds.
  • EP-A-0 106 595 that discloses a decontamination process comprising a step in which a radioactive metal material to be decontaminated is immersed into a water bath under continuous application of ultrasounds;
  • FR-A-2 590 716 that discloses a decontamination process comprising the further immersion of said contaminated material into a water solution of strong mineral acids, the control of the temperature of the bath and the application to said bath of ultrasounds at a defined frequency and power and
  • JP-A-1 233 398 a summary issued from the Patent Office of Japan, that discloses a three step process involving a first immersion in a decontamination liquid bath, a further pre-cleaning liquid bath and a final cleaning step with simultaneous application of ultrasounds.
  • the main drawback common to the prior art processes resides in an unsatisfactory effectiveness when said processes are applied to material presenting big surfaces and recesses, as it happens in said tubes particularly, so that there is always some residual radioactivity preventing from completing the decontamination, i.e. from achieving what is called in this technical field a "total decontamination" and, consequently, from reducing the waste amount to be delivered to said storages.
  • the length of above third step varies according to the strength of the acid bath and decreases as the material dissolves; preferably, a sequence of lifts and immersions is carried out; at the end of each immersion, the material is lifted from the bath in order to carry out a preliminary visual examination and the material presenting metallic gloss on its inner and outer surfaces is removed from the bath and delivered to radiometric checking.
  • the solution is considered exhaust as the iron concentration is higher than 30 g/l (the iron concentration may be determined, for instance, by a spectrophotometer).
  • this invented process is particularly suitable to decontaminate tubes of the tube nests of the heat exchangers in the nuclear power stations and more particularly tube nests of the feeding regenerators in boiling water power stations.
  • the paramount advantage of this invented process resides in that the radioactive material is decontaminated over those standards that are usually accepted for releasing non-inspected or non-conditioned material and in that the waste to be delivered to said storages, consisting in the residuals from the decontaminating solutions, are much reduced in amount.
  • a monorail 1 moves in the direction of arrow 2 a plurality of hung and conveniently spaced cages 3, each containing a set 4 of one hundred tubes each being one meter long and set in the cage vertically; each set of tubes 4 in its cage is dipped sequentially in the tanks 5, 6, 7 and 8 by hoists 9, as detailed below.
  • First tank 5 comprises an inner tank 5A and an outer tank 5B, both covered by a common cover 5C; inner tank 5A contains washing water for the tubes and in outer tank 5B is circulated a diathermic solution to keep at 55° C the temperature of the washing water in tank 5A.
  • Said solution is supplied from a suitable conventional first boiler, not shown in the figure, that gives it the required temperature; a pump, not shown in the figure, supplies the solution to the tank through inlet duct 10 and the solution comes back to said boiler through outlet duct 11.
  • Bottom exhaust means 12 allows to completely empty tank 5B, if necessary.
  • An assembly of ultrasound emitting piezoelectric transducers 13, of 20 kHz frequency, is applied to the outer of side and bottom walls of tank 5B, said transducers being of such specification and number as to maintain in the inner tank 5A an homogeneous power density of 25 Watt per liter (W/1).
  • the tank 5A inner sizes are 50 x 50 x 150 cm (150 cm height).
  • the tube set 4 is left in the washing water during a time period of 2 hours.
  • Second tank 6 recycles a steam of fresh water from an outer source through inlet and outlet ducts, not shown in the figure, to energetically wash the tubes of a set of tubes 4 dipped in said tank together with its cage 3, after removal from tank 5.
  • Tank 6 too comprises bottom exhaust means 14.
  • Third tank 7 comprises an inner tank 7A and an outer tank 7B; the inner tank contains a solution from 3,0% to 4,0% of HF (hydrofluoric acid) and from 5,0% to 6,0% of HNO3 (nitric acid) (% in volume), in water maintained at the temperature of 70° C by a diathermic solution which is supplied to tank 7B through inlet duct 15 and removed through outlet 16, similarly to the explanation referred to tank 5.
  • Tank 7A is covered by cover 17 provided with an opening connected with an intake tube 18 to remove acid vapours emitted from the solution in the tank.
  • Tank 7B is provided with a bottom exhaust means 21.
  • An assembly of ultrasound emitting piezoelectric transducers 20 is applied to the outer side and bottom walls of tank 7B, similarly to the description referred to tank 5.
  • the ratio between the total inner and outer surface of said tubes and the volume of said hydrofluoric acid and nitric acid solution in this second bath is 3 dm2/l as a maximum.
  • Fourth tank 8 is similar to tank 6 described above.
  • the decontaminated tubes are washed in running water energetically in said fourth tank 8 to release in the water the residual radioactive material particles detached from the tube outer and, in particular, inner surface.
  • This tank too is provided with a bottom exhaust means 22.
  • a cable 23 is associated with a hoist 9 supporting a cage 3 and a clamp 24 at the bottom of said cable holds said cage.
  • tanks and other parts which may be in contact with radioactive materials and with acid are made of suitable material.

Landscapes

  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Food Science & Technology (AREA)
  • Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Cleaning By Liquid Or Steam (AREA)
EP90117571A 1989-09-21 1990-09-12 Total decontamination process for radioactive metal material Expired - Lifetime EP0418722B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT2177789 1989-09-21
IT8921777A IT1232632B (it) 1989-09-21 1989-09-21 Processo di decontaminazione totale di materiali metallici radioattivi.

Publications (2)

Publication Number Publication Date
EP0418722A1 EP0418722A1 (en) 1991-03-27
EP0418722B1 true EP0418722B1 (en) 1994-12-28

Family

ID=11186713

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90117571A Expired - Lifetime EP0418722B1 (en) 1989-09-21 1990-09-12 Total decontamination process for radioactive metal material

Country Status (3)

Country Link
EP (1) EP0418722B1 (it)
DE (1) DE69015529D1 (it)
IT (1) IT1232632B (it)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102016208202A1 (de) * 2016-05-12 2017-11-16 Rwe Power Aktiengesellschaft Chemische Dekontamination von radioaktiven Metalloberflächen

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106158060A (zh) * 2016-08-23 2016-11-23 中国工程物理研究院核物理与化学研究所 一种去除放射性表面污染的超声电解自动去污系统

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3238886A1 (de) * 1982-10-21 1984-04-26 Brown Boveri Reaktor GmbH, 6800 Mannheim Verfahren und einrichtung zum entfernen von ablagerungen auf den oberflaechen der bauteile einer wassergekuehlten kernreaktoranlage
FR2586322B1 (fr) * 1985-08-14 1990-05-18 Framatome Sa Procede de nettoyage et de decontamination par ultrasons d'enceintes et dispositif correspondant
FR2590716B1 (fr) * 1985-11-26 1992-05-15 Electricite De France Procede de decontamination de parois de reacteurs nucleaires, en particulier des parois du circuit primaire des reacteurs nucleaires a circuit d'eau pressurisee

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102016208202A1 (de) * 2016-05-12 2017-11-16 Rwe Power Aktiengesellschaft Chemische Dekontamination von radioaktiven Metalloberflächen

Also Published As

Publication number Publication date
IT8921777A0 (it) 1989-09-21
DE69015529D1 (de) 1995-02-09
EP0418722A1 (en) 1991-03-27
IT1232632B (it) 1992-02-28

Similar Documents

Publication Publication Date Title
US5154197A (en) Chemical cleaning method for steam generators utilizing pressure pulsing
US4632740A (en) Apparatus and method for decontaminating metallic components of a nuclear engineering installation
US5841826A (en) Method of using a chemical solution to dislodge and dislocate scale, sludge and other deposits from nuclear steam generators
US5764717A (en) Chemical cleaning method for the removal of scale sludge and other deposits from nuclear steam generators
US5413168A (en) Cleaning method for heat exchangers
EP0458533B1 (en) Chemical cleaning method for steam generators utilizing pressure pulsing
EP0148489B1 (en) Method and apparatus for decontaminating solid surface
EP0418722B1 (en) Total decontamination process for radioactive metal material
JP2006078336A (ja) 放射性物質除染方法および化学除染装置
US3437521A (en) Radioactive decontamination
EP0484042B1 (en) Method for removing sludge and deposits from the interior of a heat exchanger vessel
KR100485973B1 (ko) 고방사능 오염 금속의 예비 산세척 장치
KR100578227B1 (ko) 방사성 금속폐기물 제염장치
JPH07253496A (ja) 放射性金属廃棄物の除染方法およびその装置
RU2695811C2 (ru) Комплексная установка дезактивации твердых радиоактивных отходов и кондиционирования образующихся жидких радиоактивных отходов
US6907891B2 (en) Radioactive substance decontamination method and apparatus
JP2653445B2 (ja) 放射性廃棄物の除染システム
JPH03152499A (ja) 部品の洗浄方法
JPS63153293A (ja) 加工物の表面処理方法
JP2002116295A (ja) 除染方法及び除染装置
EP0387886B1 (de) Verfahren zum Reinigen von Gegenständen
JP2024511366A (ja) 電気化学的表面処理装置
KR200305837Y1 (ko) 고방사능 오염 금속의 예비 산세척 장치
JP2002062397A (ja) 放射性物質で汚染された使用済機器の処理方法及び処理装置
JPH0363599A (ja) 放射能汚染機器等解体物の処理方法およびその輸送容器

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IT LI LU NL SE

RBV Designated contracting states (corrected)

Designated state(s): BE CH DE ES FR GB LI NL SE

17P Request for examination filed

Effective date: 19910611

17Q First examination report despatched

Effective date: 19930908

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): BE CH DE ES FR GB LI NL SE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Effective date: 19941228

Ref country code: FR

Effective date: 19941228

Ref country code: ES

Free format text: THE PATENT HAS BEEN ANNULLED BY A DECISION OF A NATIONAL AUTHORITY

Effective date: 19941228

Ref country code: BE

Effective date: 19941228

REF Corresponds to:

Ref document number: 69015529

Country of ref document: DE

Date of ref document: 19950209

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19950328

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Effective date: 19950329

EN Fr: translation not filed
NLV1 Nl: lapsed or annulled due to failure to fulfill the requirements of art. 29p and 29m of the patents act
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19950912

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LI

Effective date: 19950930

Ref country code: CH

Effective date: 19950930

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 19950912

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL