Preliminary study of the corrosion and radioactivity pick-up of surface-treated steels in simulated pressurised water reactor coolant

Surface and Coatings Technology 115 (1999) 1–8

Preliminary study of the corrosion and radioactivity pick-up ofsurface-treated steels in simulated pressurised water reactor coolant

D.H. Lister a,*, S. Shi a, A.S. Khanna ba Department of Chemical Engineering, University of New Brunswick, Fredericton, N.B., E3B 5A3, Canada

b Indian Institute of Technology, Powaii, Mumbai-400076, Bombay, India

Received 16 July 1998; received in revised form 24 January 1999

Abstract

In order to evaluate the potential benefits of surface-treating steels for service in water-reactor coolants, coupons of carbonsteel and the ferritic steels 21

4Cr–1Mo and 9Cr–1Mo were plasma-coated with nickel and nickel–chromium mixtures and then

surface-alloyed by irradiating with laser light from a continuous-wave CO2 laser. Subsequent exposure of the coupons to simulatedPWR primary coolant in an autoclave demonstrated that the treatments reduced corrosion and 60Co pick-up. © 1999 ElsevierScience S.A. All rights reserved.

Keywords: Plasma-sprayed chromium; Plasma-sprayed nickel–chromium; Steeb; Laser alloying; Corrosion

1. Introduction related to the erosion–corrosion found in steam-cyclefeedwater systems [2]. Furthermore, the relatively rapid

Carbon steels and low- or intermediate-alloy steels general corrosion of these steels can lead to troublesomeare used extensively in the primary and the secondary fouling deposits on primary system surfaces [3] and maycoolant systems of water-cooled nuclear reactors. In exacerbate radioactive contamination of componentsCANDU (Canada deuterium uranium) reactors, for [4].example, the piping and steam generator channel heads These, and related problems, could be mitigated, andin the primary coolant system are made of carbon steel. perhaps even eliminated, if the corrosion properties ofIn pressurized water reactors (PWRs), pressure-vessel the steels could be further controlled. Indeed, surfacesteel clad with stainless steel is used for the reactor modification of stainless steels by electropolishing hasvessel, whereas clad carbon steel is used for the steam been shown in in-plant trials to reduce substantially thegenerator channel heads. Boiling water reactors (BWRs) pick-up of radioactivity from PWR coolant, whereasuse carbon steel or alloy steels in the feedwater system electroplating with a thin layer of chromium confers aand, like PWRs, have a clad pressure-vessel steel housing further advantage (by a factor of ten or so) [5].the reactor core. Treatment of carbon and ferritic steels by plasma coating

In general, these materials exhibit acceptable behavi- with suitable alloying materials followed by laser irradia-our in their reactor environments; however, problems tion to alloy the surface has been shown to hold promisecan arise under certain circumstances. Defects in clad as a technique for improving resistance to both wearoverlay can lead to localized corrosion of underlying and corrosion in several environments [6 ]; so, it seemssteels for example [1], and carbon steel piping exposed likely that such surface treatments will confer advantagesto high-velocity coolant leaving a CANDU core may on steel in reactor coolants also. Therefore, as a screen-experience accelerated corrosion caused by a mechanism ing study, we have tested coated steels in simulated

PWR coolant to determine their corrosion and radioac-tive contamination behaviour. This study, as a possible* Corresponding author. Tel.: +1-506-453-4639;preliminary to more detailed work under a range offax: +1-506-453-3591.

E-mail address: [email protected] (D.H. Lister) coolant conditions, is reported here.

0257-8972/99/$ – see front matter © 1999 Elsevier Science S.A. All rights reserved.PII: S0257-8972 ( 99 ) 00043-2

2 D.H. Lister et al. / Surface and Coatings Technology 115 (1999) 1–8

Table 1Chemical composition of carbon steel, 21

4Cr–1Mo and 9Cr–1Mo steel

Steel Composition (wt.%)

C Si Cr Mo Ni Cu Mn Fe

Carbon steel 0.069 0.041 <0.01 – – <0.01 0.38 balance214

Cr–1Mo 0.120 0.23 2.25 1.00 0.16 0.13 0.46 balance9Cr–1Mo 0.09 0.27 8.45 0.99 0.16 0.13 0.37 balance

2. Experiments simulated PWR coolant in a 2 l static autoclave madeof Hastelloy-C that had been supplied by Autoclave

The materials used in the study were carbon steel Engineers. The autoclave, which had previously beenand the ferritic steels 21

4Cr–1Mo and 9Cr–1Mo (equiva- used for an experiment involving radioactivity, was

lent to UNS G10060, K21590 and K81590 respectively). decontaminated with a mixture of weak acids andTheir chemical compositions are given in Table 1. complexing agents and then rinsed thoroughly with

Sheet material, 2.5 mm thick, was made into roughly deionized water before being assigned to this experiment.circular coupons about 1 cm in diameter and ranging in The coolant contained boric acid and lithium hydroxidemass from 1.2 to 1.9 g; some were pre-treated by degreas- at concentrations in deionized water of 600 ppm (as B)ing and sand blasting, whereas some were merely and 3.5 ppm (as Li) respectively; these corresponded todegreased. Two types of coating were plasma-sprayed a pH300°C of 7.4. A few drops (about 0.1 ml ) of a diluteonto the two major surfaces of pre-treated coupons of solution of cobalt nitrate, made up from solid cobalticeach material: a single layer of chromium and a duplex oxide that had been irradiated in the research reactorlayer of nickel overlaid with chromium. The coupon at McMaster University, Hamilton, Canada, and thenedges remained untreated. The parameters of the plasma dissolved in nitric acid, were also added to the autoclavecoating process are presented in Table 2. to give a concentration of radioactive 60Co of 0.04 mCi/l

After being coated, the coupons were treated with (1 Ci¬3.7×1010 Bq). All chemicals used in the experi-laser irradiation using a 5 kW continuous-wave CO2 ment were analytical grade. The autoclave was spargedlaser. The laser beam was adjusted to a line focus (‘spot’

with hydrogen gas at atmospheric pressure for severalsize 6 mm×0.5 mm, which gave an energy density

hours at the start of the run to ensure deaeration. Aof 100 kW/cm2), so that maintaining a sweep speed ofthermocouple mounted in a thermowell sealed into the500 mm/min resulted in a surface interaction time ofautoclave lid controlled the coolant temperature during60 ms.the run at 300±0.5°C via a jacket heater.After surface treatment, representative coupons were

After being weighed, coupons were secured in indivi-sectioned and polished and profiles of the alloyingdual ‘cages’ of twisted stainless steel wire and mountedelements below the surface determined with energy-on a coupon holder made of stainless steel rod thatdispersive X-ray analysis (EDAX ) in a scanning electronstood on the bottom of the autoclave. The cages affordedmicroscope (SEM). The major surfaces (i.e. the faces)only three-point contact between the wire and the edgesof treated and untreated coupons were also studied inof the coupons to minimize the possibility of galvanicthe SEM, topographical features were photographedeffects influencing corrosion during exposure in theand EDAX analyses were obtained. Table 3 indicatesautoclave (examination after the run in fact showed nothe thickness of the coatings as deduced from theobvious signs of galvanic effects associated with theEDAX profiles.coupon mounting).Both treated and untreated coupons were exposed to

After the run was started, the system took aboutTable 2 three hours to reach the control temperature of 300°CPlasma coating processing parameters in the autoclave. The experiment continued for 670 h,

after which the system was cooled down and the couponsCoating Cr Ni Cr overlaying Niremoved. They were carefully rinsed with deionized

Torch power (kW ) 16 12 10 water, dried, weighed, counted for radioactivity pick-upCurrent (A) 400 300 250 with a calibrated gamma spectrometer (intrinsic GeVoltage (V ) 40 40 40

detector and electronics supplied by CanberraPlasma gas: Ar+N2 ( l/min) 20+1 20+2 20+1Industries) then examined in the SEM and analysedPowder feed rate (g/min) 22 22 15

Particle size (mm) 90 40 90 by EDAX.Argon carrier gas ( l/min) 10 10 8 The coolant conditions in the autoclave at the startSpecimen–torch distance (mm) 100 100 100

of the run are summarised in Table 4.

3D.H. Lister et al. / Surface and Coatings Technology 115 (1999) 1–8

Table 3Thickness of coatings

Coupon Carbon steel 214

Cr–1Mo 9Cr–1Mo

Coating Cr Ni–Cr Cr Ni–Cr Cr Ni–Cr

Thicknessa (mm) 270 575 320 415 295 380

a As indicated by the EDAX profile at the position where the Cr or Ni concentration is 10% greater than that in the bulk.

3. Results and Zn, are expected to be readily accommodated inthe crystal lattice of a magnetite-based oxide [7].

The chromium treatment of the carbon steel produced3.1. Coupon appearancea structure of roughly equiaxed grains, each 10–20 mmacross. Occasionally, a morphology resembling overlap-The exposure to the simulated PWR coolant duringping triangular plates resulted [see Fig. 1(b)]. Thethe 670 h experiment changed all untreated surfaces —boundaries of these grains were usually ‘decorated’ withincluding the edges of treated coupons — from thedeposit, imparting a cloisonne appearance to the surface.original metallic finish to a dull dark grey or black.A few minute surface cracks were visible in the SEM atTreated surfaces, which originally had a yellowish tingehigh magnification. Exposure in the autoclave had noresembling a tarnish film, were apparently unchangedtopographical effect that could be discerned with theby the exposure.SEM; since the Cr:Fe ratio remained the same at about4:1, the major differences between EDAX analyses3.2. Surface analysis: carbon steelbefore and after exposure were the disappearance of thesmall amount of Ni (0.3%) and most of the 4.5% SiScanning electron micrographs of carbon steel cou-(presumably contamination introduced during thepons before and after exposure are presented inplasma spraying or from the sand blasting pre-treat-Fig. 1(a)–(c) (it should be noted that the same regionsment) and the appearance of a small proportion of Znof the surfaces as had been examined and photographed(0.3%). It is presumed that the air-formed oxide film onbefore the exposure were again located in the SEM afterthe freshly treated coupon, probably of a chromitethe exposure in order to achieve the most meaningfulstructure based on Cr2O3 (and containing somecomparisons).FeCr2O4 resulting from the incorporation of iron fromAs Fig. 1(a) indicates, untreated carbon steel, whichthe substrate), was protective enough to avoid altogetheroriginally bore traces of a thin scale on its surface,the formation of ferrite crystals as an outer oxide layerdeveloped during the exposure a rather coarse, irregularduring the exposure. These ferrites, which impart com-scale dotted with oxide crystals up to about 1 mm inparatively little protection, are usually ubiquitous insize. During exposure the coarse scale (which was mostlylow-alloy steel systems exposed to high-temperaturean oxide of iron, Fe) was deposited with about 1% Ni,water and in fact, like the magnetite mentioned earlier,1% Cu and 0.33% Zn (as proportions of the metals inwould have formed the basis of the rough oxide scalethe oxide — presumed to be based on magnetite,grown during the exposure of untreated surfaces. ThatFe3O4); the Ni no doubt originated mostly as a corrosionthe chromites form strongly with Zn but not with Niproduct of the Hastelloy autoclave, whereas the Cu andunder hydrothermal conditions [7] supports the postu-Zn were probably contaminants from the water orlate of a chromite-based protective oxide that undergoeswater-treatment chemicals or residue from the previoussome ion-exchange during exposure to lose Ni andrun in the autoclave that had survived the pre-experi-gain Zn.ment cleaning. Ions of these metals, particularly the Ni

Before-exposure and after-exposure pictures of theNi–Cr-treated carbon steel are presented in Fig. 1(c).Table 4The dual treatment has produced a structure resemblingNominal coolant conditions in the autoclave during the experimentoverlapping plates, 10–15 mm across, even more than

Temperature (°C) 300 the single Cr treatment did. Triangular structures seemPressure (MPa) 9 to have predominated this time, and surface crackingBoron concentration (ppm) 600

was more pronounced than with the single Cr treatment.Lithium concentration (ppm) 3.5Exposure in the autoclave again had no effect discerniblepH300°C 7.4

Dissolved hydrogen (cm3/kg) 18 in the SEM, whereas EDAX analyses indicated that anDissolved oxygen (mg/kg) <10 air-formed, chromite-based oxide containing iron wasDissolved 60Co (nCi/l ) 40 probably formed as a result of the plasma and laserExposure time (h) 670

treatment and preserved during autoclave exposure. The


Fig. 1. Carbon steel coupons before ( left) and after (right) exposure: (a) untreated; (b) Cr-coated; (c) Ni-Cr-coated.

surface gained about 0.7% Zn during exposure, but lost steel, small proportions (~1% or less) of Ni and Znnearly all of the 8% Si that was present after surface were gained.treatment — again, assumed to be a contaminant from Single surface treatment with Cr produced a largelythe coupon preparation processes. The Cr:Fe ratio was ‘pebbled’ surface with individual particles reaching 2 mmreduced from just under 6:1 to about 4.5:1. in diameter [Fig. 2(b)]. Some of the particles appeared

faceted and there were areas where arrays of particles3.3. Surface analysis: 21

4Cr–1Mo were aligned on the substrate. Underlying the pebbling

was a layer of smaller particles each about 0.1–0.2 mmacross. The surface showed little evidence of cracking —

–

Fig. 2(a)–(c) presents the SEM pictures of themerely one or two indications of very fine cracks less21

4Cr–1Mo coupons before and after exposure. The

than 10 mm long. Exposure in the autoclave had nountreated material in the high-temperature coolanteffect on the surface features. Analysis by EDAX showeddeveloped a fairly uniform coating of small crystals,that the metal proportions were altered by the high-0.1–0.3 mm in diameter, overlaid with patches of antemperature coolant — the loss of most of a 12% Siirregular deposit up to 10 mm across [Fig. 2(a)]. Thecontaminant, the gain of 2.3% Zn and the reduction ofsurface Cr content, as determined by EDAX, increasedthe Cr:Fe ratio from about 20:1 to about 9:1.from 2.4% to 6.6% as the oxide film developed during

the exposure and, as in the case of the untreated carbon The dual treatment with Ni and Cr gave a varied


Fig. 2. 214

Cr–1Mo steel coupons before ( left) and after (right) exposure: (a) untreated; (b) Cr-coated; (c) Ni–Cr-coated.

topography ranging from regions of aligned overlapping uniform oxide crystals, 1–2 mm in diameter, during theexposure [Fig. 3(a)]. Analysis by EDAX indicated thatplates (triangles or hexagons up to 10 mm across), withthe oxide was mostly iron-based, so it was assumed to1–2 mm particles embedded in the surface here and there,be magnetite; Cr was present in some crystals (averagingto a rather roughly pebbled surface based on particlesto 6.9% Cr over the surface) and Ni was present (to 2–of 4–5 mm in diameter [Fig. 2(c)]. The surface was3%) but in only a very few crystals.extensively cracked — particularly in the pebbled areas.

Surface treatment with Cr produced partial coverageExposure to coolant in the autoclave did little to changewith layers that had convoluted outlines [Fig. 3(b)].the appearance of the surface, but it did affect theSmooth pits distributed across the layers held particlescomposition; again, it removed most of an Si contami-up to 2–3 mm in diameter. Dendritic growths 10–20 mmnant (from 11%), added Zn to about 2% and reducedlong by 2–3 mm across were scattered over the wholethe Cr:Fe ratio from about 8:1 to less than 6:1.surface. The surface was badly cracked, and the pre-treatment had contaminated the surface with up to 21%3.4. Surface analysis: 9Cr–1MoSi. Exposure in the autoclave had no visible effect on

The surface appearance of the 9Cr–1Mo coupons the surface topography except to open up some of thebefore and after exposure in the autoclave is illustrated cracks slightly, but the Si concentration was reduced toby the SEM pictures in Fig. 3(a)–(c). The untreated about 1%, about 2% Zn was added and the Cr:Fe ratio

was reduced from about 20:1 to about 10:1.material clearly developed a dense covering of fairly


Fig. 3. 9Cr–1Mo steel coupons before ( left) and after (right) exposure: (a) untreated; (b) Cr-coated; (c) Ni–Cr-coated.

The dual treatment with Ni and Cr covered the autoclave, it must be remembered that the edges of thetreated coupons were not subjected to the coating treat-surface with mostly triangular growths, many of them

overlapping, up to 5 mm across (Fig. 3c). These were ment. Since about one-third of the surface area of acoupon was on the edge (0.82 cm2 versus 1.57 cm2 forinterspersed with dendrites and round particles 2–3 mm

in diameter. Many small cracks following the contours the two faces) a misinterpretation could have occurredif the difference in behaviour between edges and facesof the growths were found, along with several larger

cracks across much of the specimen surface. Silicon of a treated coupon had not been accounted for. Thecorrection was made by measuring the weight changecontamination reached about 15%. Autoclave exposure

again opened up the cracks slightly but had no other per unit area of the appropriate untreated coupon andthen assuming that the edges of the treated coupons ofeffect discernible in the SEM. The Si concentration was

reduced to 3%, however, and the Cr:Fe ratio fell from that material behaved in the same way. The couponswere not perfectly circular, so equivalent diameters andabout 35:1 to about 8:1.surface areas were estimated from the weights and theassumption that the material was 2.5 mm thick and of3.5. Weight changes during exposurea density 7.9 g/cm3. The dimensions and weights arepresented in Table 5. Note that since the untreatedWhen changes in weight of the coupons are consid-

ered as indicators of corrosion during exposure in the coupons developed substantial oxide films their mea-


Table 5Coupon dimensions and weight changes caused by autoclave exposure

Material Equivalent Measured weight Apparent weight loss Apparent penetrationdiameter (cm) change (mg) from faces (mg/cm2) of facesb (mm)

Carbon steeluntreated 1.08 −2.28 0.851a –Cr-coated 1.08 −1.14 0.227 0.32Ni–Cr-coated 0.96 −1.00 0.247 0.34

214

Cr–1Mountreated 0.89 −0.86 0.440a –Cr-coated 1.10 −0.70 0.167 0.23Ni–Cr-coated 1.11 −0.94 0.285 0.40

9Cr–1Mountreated 0.94 +0.28 −0.132a –Cr-coated 1.05 −0.40 0.295 0.41Ni–Cr-coated 1.12 −0.44 0.283 0.39

a Based on total coupon surface area.b Weight loss from faces attributed to Cr, density 7.2 g/cm3.

sured weight changes were the net result of some oxygen 3.6. Pick-up of 60Copick-up and some metal loss, so no attempt was made

Radioactive contamination of the treated couponsto estimate the corresponding corrosion. The treatedalso had to be corrected for the fact that the couponsurfaces developed no visible oxides, so the weightedges were not treated. Again, it was assumed that thechanges of treated coupons were adjusted for edge effectsedges behaved like the corresponding untreated cou-and attributed to the faces.pons, and adjustments to measurements of 60Co concen-The untreated 9Cr–1Mo, which displayed the densetration on the total surfaces were made accordingly.oxide film in the SEM after exposure, registered a weightThe resulting estimates of 60Co concentration on thegain. It is interesting to note that if the weight gain ofcoupon faces are presented in Table 6.the untreated 9Cr–1Mo coupon is attributed solely to

oxygen pick-up, and if it is assumed that the oxide wasmagnetite and that there was no loss to the coolant, the

4. Discussionmetal corroded amounted to 0.339 mg/cm2. Since, how-ever, all other coupons lost weight, it is likely that the

It is clear that the coated surfaces have demonstrateduntreated 9Cr–1Mo lost weight also, so the actuala remarkable resistance to general corrosion, remainingcorrosion was probably greater than 0.339 mg/cm2.virtually unchanged over the 670 h of exposure to simu-lated PWR coolant — at least, as far as the topographyrevealed by the SEM is concerned. That the coupon

Table 6 weight changes, even after adjustment for the effects of60Co contamination of coupons

the untreated edges, do not reflect this apparent inert-ness — even though they do indicate an overall benefitMaterial Overall radioactivity Radioactivity on

(nCi/cm2) faces (nCi/cm2) of the treatments — is not altogether surprising. Therewould have been a tendency during the exposure of a

Carbon steelcoupon for the coating to be cathodically protected byuntreated 1.36 1.36the rather large area of the corroding edge. The edgeCr-coated 1.26 1.21

Ni–Cr-coated 0.754 0.439 itself, as the anode, would therefore corrode more thanthe corresponding untreated coupon and the weight21

4Cr–1Mo

untreated 1.37 1.37 correction would be insufficient. Indeed, it is clear thatCr-coated 0.993 0.822 the last two columns in Table 5 greatly overestimate theNi–Cr-coated 1.11 0.993 corrosion of the treated faces, for the effects of the

9Cr–1Mo indicated weight losses would have been obvious in theuntreated 1.56 1.56 SEM had they been present.Cr-coated 1.08 0.851 Some of the changes in surface composition duringNi–Cr-coated 1.12 0.923

exposure as indicated by EDAX are puzzling. The


affinity of a chromite oxide film for zinc is now well 670 h to simulated PWR coolant containing dissolved60Co demonstrated that corrosion and radioactive con-established, as pointed out earlier, so the increase in Zn

content of the surfaces of a few percent is readily tamination were lower on the treated surfaces than onuntreated surfaces. In fact, SEM examination confirmedattributable to its incorporation in the passivating oxide

film, which could have taken place with little or no that the surface topography of treated specimens wasessentially unchanged by the exposure. Galvanic effectsvisible change in topography. The larger composition

changes, however, particularly the loss of most of the between the major surfaces of treated specimens and theuntreated edges led to uncertainties in the absoluteSi contamination (amounting to up to 21% as Si) and

the general halving or more of the Cr:Fe ratio, could values of corrosion and radioactivity pick-up, so neithertreatment could be said to be superior, though the dualhardly have occurred without altering the topography

substantially. These results remain unexplained. Ni–Cr coating led to more surface cracking. Elementalanalyses of treated specimens indicated changes in sur-The surface treatments also reduced the affinity of

the steels for 60Co, as indicated by Table 6. Since the face composition, brought about by exposure in theautoclave, that are difficult to reconcile with the SEMcorrosion process and the accompanying development

of an oxide film in high-temperature water greatly observations. In general, the treatments show promisefor passivating carbon steel and ferritic steels in reactorinfluence the pick-up of 60Co [7], it is likely that the

galvanic effects that must have modified the weight coolants, and further development to obtain more-uniform, crack-free coatings is recommended, along withchanges also modified the radioactivity values. The edge

corrections incorporated in the last column of Table 6 further autoclave testing of specimens with minimalgalvanic effects followed by detailed surface analysis.will therefore be insufficient. The minimal development

of an oxide film on the treated surfaces during autoclaveexposure suggests that the coupon faces would in facthave picked up very little 60Co; important contamination Acknowledgementsmechanisms under those circumstances would have beenadsorption and ion exchange within the existing protec- The plasma coating of the treated coupons was

carried out at the Laser and Plasma Division of thetive oxide films.These uncertainties in the corrections make it difficult Bhaba Atomic Research Centre, Bombay, India and the

laser irradiation at the Fraunhofer Institute for Laserto pronounce upon the relative effectiveness of the singleCr treatment or the dual Ni–Cr treatment. Certainly, Technique, Aachen, Germany. Those institutes are

thanked for providing the necessary facilities.from the points of view of corrosion and radioactivecontamination, the latter had no great advantage and, J. McInerney and N. Arbeau of the University of New

Brunswick are also thanked for assistance with thein fact, had a somewhat larger tendency than the formerto display surface cracks — as revealed by the SEM autoclave exposures and the radioactive counting.examination. It is clear, however, that the treatmentsoverall confer a benefit. Extended testing of treatmentsmodified to produce more uniform, crack-free surfaces References(which are less prone to promote localized corrosionduring long service in high-temperature water) and using [1] J. Kysela, Coolant Technology of Water Cooled Reactors, IAEA-

TECDOC-667, Sept. 1997, vol. 2, International Atomic Energysamples with minimal galvanic effects from untreatedAgency, Vienna, Austria, 1997.edges is the logical next step in the qualification of these

[2] D.H. Lister, J. Slade, N. Arbeau, in: J.V. Donnelly, A. Oliva (Eds.),surface-processing techniques for service in reactor cool- Proceedings of the 1997 CNA/CNS Annual Conference, Toronto,ants. Such qualification should include more detailed Canada, vol. 1, Canadian Nuclear Association, Toronto, Canada,

1997.surface analyses and examinations of the samples tested.[3] K.A. Burrill, C.W. Turner, Proceedings of the 2nd CNS Interna-

tional Conference on Steam Generators and Heat Exchangers,Toronto, Canada, vol. II, Canadian Nuclear Association, Toronto,Canada, 1994, p. 7.125.

[4] N. Arbeau, H. Allsop, R.H. Campbell, D.H. Lister, Corrosion 545. Summary and conclusions (6) (1998) 459–468.

[5] M.J.B. Hudson, H. Ocken, Proceedings of the 7th BNES Interna-tional Conference on Water Chemistry of Nuclear Reactor Systems,The treatment of specimens of carbon steel,Bournemouth, UK, vol. 1, British Nuclear Energy Society,21

4Cr–1Mo steel and 9Cr–1Mo steel by plasma-spraying

London, UK, 1996, p. 9.coatings of Cr or Ni–Cr followed by laser-alloying gave, [6 ] A.K. Pattanaik, A.S. Khanna, C.S. Harendranath, K. Wissenbach,on a microscopic scale, rather irregular surfaces with G.L. Gowami, Bull. Mater. Sci. 18 (2) (1995) 169.

[7] D.H. Lister, Nucl. Energy 32 (2) (1993) 103–114.some cracking. Subsequent exposure in an autoclave for

Documents

Preliminary study of the corrosion and radioactivity pick-up of surface-treated steels in simulated pressurised water reactor coolant