Cladding for a fuel rod for a light water reactor

Patent metadata

Field	Value
Publication number	US-2018366234-A1
Application number	US-201616060346-A
Country	US
Kind code	A1
Filing date	Dec 15, 2016
Priority date	Dec 15, 2015
Publication date	Dec 20, 2018
Grant date	—

Abstract

A fuel rod cladding (4) for a light water reactor includes a core (16) including a matrix consisting of pure molybdenum or of a molybdenum-based alloy; and an outer protective layer (18). The outer protective layer (18) is selected among a chromium-based coating (20) deposited on an outer surface of the core (16) that includes at least one chromium-based coating layer (24) consisting of pure chromium or of a chromium-based alloy; a chromium-based diffusion layer (22) obtained by diffusion of chromium into the core (16) from the outer surface of the core (16); or a succession of a chromium-based diffusion layer (22) obtained by diffusion of chromium into the core (16) from the outer surface of the core (16) and a chromium-based coating (20) consisting of chromium or of a chromium-based alloy deposited on the outer surface of said core (16).

First claim

What is claimed is:

1 - 18 (canceled)

19 . A fuel rod cladding for a light water reactor, comprising:
a core comprising a matrix consisting of pure molybdenum or of a molybdenum-based alloy; and an outer protective layer, the outer protective layer being selected among:
a chromium-based coating deposited on an outer surface of the core, the chromium-based coating comprising at least one chromium-based coating layer consisting of pure chromium or of a chromium-based alloy;
a chromium-based diffusion layer obtained by diffusion of chromium into the core from the outer surface of the core; and
a succession of a chromium-based diffusion layer obtained by diffusion of chromium into the core from the outer surface of the core and a chromium-based coating consisting of chromium or of a chromium-based alloy deposited on the outer surface of the core.

20 . The fuel rod cladding according to claim 19 , wherein the core further comprises particles dispersed within the matrix of pure molybdenum or of the molybdenum-based alloy.

21 . The fuel rod cladding according to claim 19 , wherein the core consists of the matrix of pure molybdenum or of a molybdenum-based alloy.

22 . The fuel rod cladding according to claim 19 , wherein the molybdenum-based alloy comprises at least 85 wt. % of molybdenum.

23 . The fuel rod cladding according to claim 19 , wherein the chromium-based diffusion layer is obtained through chromizing by pack cementation using a powder mixture comprising metallic chromium or by chemical vapor deposition.

24 . The fuel rod cladding according to claim 23 , wherein the powder mixture comprises at least 15 wt. % of metallic chromium.

25 . The fuel rod cladding according to claim 19 , wherein the chromium-based coating is obtained through physical vapor deposition or through chemical vapor deposition.

26 . The fuel rod cladding according to claim 25 , wherein the chromium-based diffusion layer is obtained through heat treatment of the chromium-based coating deposited on the outer surface of the core.

27 . The fuel rod cladding according to claim 19 , wherein the outer protective layer has a thickness comprised between 2 μm and 100 μm.

28 . The fuel rod cladding according to claim 19 , further comprising an inner protective layer, the inner protective layer being selected among:
a chromium-based coating deposited on an inner surface of the core, the chromium-based coating consisting of pure chromium or of a chromium-based alloy; and a chromium-based diffusion layer obtained by diffusion of chromium into the core from the inner surface of the core.

29 . A fuel rod comprising the fuel rod cladding according to claim 19 .

30 . A method for manufacturing a fuel rod cladding for a light water reactor, comprising steps of:
providing a core comprising a matrix consisting of pure molybdenum or of a molybdenum-based alloy; and forming an outer protective layer, the forming of the outer protective layer comprising at least one of:
depositing a chromium-based coating consisting of pure chromium or of a chromium-based alloy on an outer surface of the core, the deposition step comprising depositing at least one chromium-based coating layer; and/or
forming a chromium-based diffusion layer by diffusion of chromium into the core from the outer surface of the core.

31 . The method according to claim 30 , wherein the forming of the chromium-based diffusion layer comprises chromizing by pack cementation, using a powder mixture comprising metallic chromium.

32 . The method according to claim 31 , wherein the powder mixture further comprises one or more diffusion elements to improve corrosion resistance.

33 . The method according to claim 30 , wherein the forming of the chromium-based diffusion layer comprises chromizing through chemical vapor deposition.

34 . The method according to claim 30 , wherein the depositing of the chromium-based coating comprises depositing at least one chromium-based coating layer of the chromium-based coating through chemical vapor deposition (CVD) or through physical vapor deposition (PVD).

35 . The method according to claim 30 , wherein the chromium-based coating consists of several superposed chromium-based coating layers and the depositing of the chromium-based coating comprises depositing each of chromium-based coating layers of the chromium-based coating through chemical vapor deposition (CVD) or through physical vapor deposition (PVD).

36 . The method according to claim 30 , wherein at least one chromium-based coating layer of the chromium-based coating is deposited on the outer surface of the core prior to forming the chromium-based diffusion layer, and forming of the chromium-based diffusion layer comprises a heat treatment of the at least one chromium-based coating layer of the chromium-based coating.

37 . The method according to claim 36 , wherein the heat treatment is carried out at a temperature of at least 900° C.

38 . The method according to claim 30 , wherein the depositing of the chromium-based coating comprises depositing several coating layers, at least some of the steps of depositing a coating layer comprising subjecting the coating layer to a heat treatment such that chromium from the coating layer diffuses into an underlying coating layer and/or into the core, the diffusion into the core possibly coinciding with the forming of the chromium-based diffusion layer.

Assignees

• Framatome Sa

Inventors

• Hertz Dominique
• Bischoff Jérémy
• Guillermier Pierre

Classifications

• G21C3/20 Primary

  with coating on fuel or on inside of casing; with non-active interlayer between casing and active material {with multiple casings or multiple active layers} · CPC title

• C23C28/023

  only coatings of metal elements only · CPC title

• G21C3/07

  characterised by their material, e.g. alloys · CPC title

• C23C16/10

  Deposition of chromium only · CPC title

• C23C10/38 Primary

  Chromising · CPC title