The competing influences of void swelling and radiation ...envdeg2015.org/final-proceedings/ENVDEG/papers/ENVDEG021.pdf · the two competing effects in order to develop fully-predictive

17th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors

August 9-13, 2015, Ottawa, Ontario, Canada

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The competing influences of void swelling and radiation-induced precipitation on dimensional stability and thermal-physical properties

of austenitic stainless steels in PWR and VVER internals

F. A. Garner1*

, A. V. Kozlov2, T. Okita

3

1Radiation Effects Consulting, Richland WA, USA

2FSUE Institute of Nuclear Materials, Zarechny, Russia

3University of Tokyo, Japan

ABSTRACT

It is well-known that voids and bubbles induced by displacive irradiation lead to significant changes in

many physical properties, including lattice parameter, bulk density, elastic modulii, Poisson's Ratio,

electrical/thermal conductivities, ultrasonic velocity and others. Less well-known is that radiation-induced

formation of precipitates can also induce changes in these same properties, but sometimes in the opposite

direction from that arising from voids. Since void formation in both Western and Russian austenitic steels

is often concurrent with or preceded by phase formation, it is necessary to separate the contributions of

the two competing effects in order to develop fully-predictive correlations of swelling and irradiation

creep. This paper presents a summary of experimental observations and demonstrates that in principle

such separation can be accomplished. It is also shown that radiation-induced modification of physical

properties allows in-situ non-destructive measurements to be used to measure swelling in LWR structural

components. For relatively thin components, electro-resistive measurements appear to yield better results,

but for thicker components ultrasonic techniques are more practical and effective. The impact of

precipitate/void effects on data interpretation is also discussed, especially with respect to creep relaxation

of preloaded components and for development of predictive correlations for void swelling and creep.

Keywords: structural steels, void swelling, irradiation creep, precipitation, changes in thermal-physical

properties, ultrasonic velocity, elastic modulii, electrical resistivity

1.0 Introduction

Structural steels used in the construction of LWR internal structures begin their service in a

condition representing their optimum properties, but there is an inevitable and progressive

deterioration of their various properties as they experience the cumulative effects of elevated

temperature, displacement damage, stresses and other environmental factors. Summaries of the

changes in austenitic steel properties and dimensions experienced during reactor operation are

presented elsewhere [1,2].

In order to manage and track this deterioration it is necessary to develop predictive correlations

for changes in thermal-physical properties, mechanical properties and especially for changes in

dimension arising from void swelling, irradiation creep and precipitation. The latter's

contribution to dimensional distortion is often thought to be a minor contribution compared to

those of swelling and irradiation creep and therefore can be ignored, but this assumption is not

always correct and can lead to correlations that may incorrectly predict the eventual behavior,

especially when low-fluence data are extrapolated to higher fluence. Additionally, if non-

destructive measurements based on changes in physical properties are to be used to measure



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swelling in-situ in the LWR core, then saturable dimensional changes arising from precipitation

and matrix microchemistry must be separated from non-saturable changes arising from swelling

and irradiation creep.

Voids formed in irradiated materials will not only change the dimensions of a structural

component via swelling and swelling-enhanced creep, but will also directly induce changes in

many of its physical properties. One of the earliest analytical treatments on this subject was

provided by Wolfer and Garner in the early 1980s [3], but this effort did not consider companion

effects arising from precipitation and concurrent microchemical changes in matrix composition.

Later treatments of void-induced changes in physical properties recognized the possibility of

microchemical contributions but did not directly address the issue [4-6].

It was known since the early 1970s that relatively small to moderately large volume changes

occurred as a result of carbide precipitation [7] and that the formation of other phases such as

gamma-prime, G-phase and intermetallics also gave rise to volume changes, some positive and

some negative [1,2,8,9], but the synergistic interaction of void and microchemical effects was

not sufficiently appreciated at that time.

It was later realized that precipitation often preceded the onset of void nucleation in austenitic

steels, removing from the matrix elements that tend to suppress void nucleation such as

phosphorus, silicon, carbon and nickel [1,2]. Additionally, it was noted that the aggregate

changes arising from changes in matrix and precipitate properties did not always cancel, but

sometimes produced a net change in alloy density or physical property. For instance, carbon has

a different partial molar volume in the carbide and matrix, thereby producing a net densification

of the alloy upon precipitation even though the carbide itself is less dense than the matrix [7].

Carbon is not the only element whose removal can alter the density of the alloy matrix.

Straalsund and Bates showed that in 316 stainless steel carbon (+53.9%) and nitrogen (+45.1%)

exhibit large positive size factors. These factors are deviations from ideal solution behavior,

indicating the degree of misfit or lattice distortion [10]. Of the substitutional elements only

molybdenum was observed to have a significant misfit or size parameter at +35.9%, but other

elements had variations of 10% or less. However, even variations of <10% can have an effect to

change the net lattice parameter upon precipitation and even by segregation not leading to

precipitation [11-13]. Chromium has a size parameter of +4.8% , nickel has a value of -3.2% and

silicon has a value of -2.75%, indicating that removal of chromium into carbides assists carbon

removal to decrease the density, while formation of nickel and silicon rich gamma prime and G-

phase precipitates tend to increase the density.

There are other consequences to removal of solutes into precipitates that lead to net changes in

physical properties. Examples are changes in electrical and thermal conductivities, but there can

be rather large changes in elastic modulii where solutes involved in solution hardening are not as

effective to harden when concentrated in precipitates. If precipitation removes from the matrix

those elements that are particularly efficient as solution-hardening contributions, the matrix must

soften, a consideration not always reflected in published Orowan hardening calculations.

Thus, precipitation can have both positive and negative contributions to hardening, and ignoring

matrix-softening will lead to different values of apparent hardening coefficients of various

obstacles, especially in alloys containing significant amounts of Ti and C. Such a situation was

encountered in recent work by Tsay and coworkers for a Russian alloy strengthened by C and Ti,

where significant matrix softening accompanied radiation-stimulated precipitation of very fine



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TiC precipitates [14]. Using experimental solution-hardening values provided for C by Irvine

and coworkers [15] and for Ti by Gessel [16], Tsay was able to match hardening measurements

of a wide range of microstructural states arising from various post-irradiation annealing heat

treatments of the same alloy, calculating Orowan strengthening with traditional values of barrier

hardening, but with significant matrix softening included as a result of TiC precipitation.

Of particular significance to this paper, it should be noted that the ultrasonic velocity of an alloy

is dependent on both the elastic modulii and the alloy density, with the latter decreasing with

void swelling, but increasing with carbide precipitation. This situation provides the basis for an

NDE technique to identify the combined effect of swelling and precipitation. Separating the two

contributions, however, requires a special specimen set, as will be discussed later in this paper.

For stainless steels used in LWR service the most prominent example of net volume change is

the net densification of 300 series steels as carbon is removed from solution into various metal

carbide precipitates. As discussed in reference [7] the distribution of these strains is often

anisotropic, reflecting the tendency of carbides to precipitate on dislocations, thereby being

strongly influenced by the dislocation texture in the steel. The total strains are proportional to the

carbon content and tend to increase with irradiation temperature, but in general never exceed

~1% for typical carbon levels found in 300 series stainless steel. The radiation-induced strains

are usually of the same magnitude as those produced by thermally-induced precipitation [17], but

the size, density and location of thermal precipitates is usually very different.

While these strains are small in magnitude they tend to develop and saturate early in the

irradiation, and thereby contribute a significant fraction of early total strain, complicating

analysis of strain data and providing difficulty in extrapolation to higher exposures. Carbide-

induced strains are negative and therefore tend to camouflage the onset of void swelling and also

irradiation creep, both of which can produce positive strains. Excellent examples of carbide-

induced densification are shown in Fig. 1 for steels characteristic of French PWRs [18]. Note

that the variability in measurements from specimen to specimen was thought to arise from

inadequate wetting of specimens during immersion density measurements, but data trends clearly

indicate densification is occurring. The reversal in density change in 316 with increasing dose

may reflect the onset of void swelling, a process observed in many previous studies [1,2]. In

addition to higher Ni and Mo, the 316 steel had a higher C level, all of which affect densification

and swelling, complicating comparison of the two steels. Additionally, the higher nickel level of

316 also allows positive strain contributions to develop from gamma prime formation.

Fig. 1. Densification observed in multiple specimens of two 300 series steels irradiated as tensile

specimens in the same capsule in the BOR-60 fast reactor at ~330°C [18]. The annealed 304

steel had 0.022 weight percent carbon and the cold-worked 316 steel had 0.054% carbon.



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In the same BOR-60 irradiation series these steels were also irradiated as pressurized tubes,

producing results shown in Fig. 2 (left). Note that when the data are plotted vs. (MPa.dpa), the

strains are very linear as should be expected for irradiation creep in the absence of significant

swelling [1]. The non-zero intercept, however, is most likely a consequence of carbide

densification, partially camouflaging positive creep strains in the tube diameter. Note that Fig. 2

(right) shows very similar behavior in similar creep tubes irradiated in the OSIRIS reactor [19].

Fig. 2 Irradiation creep behavior of SA 304L and CW 316 irradiated in BOR-60 (left) and

OSIRIS (right) reactors, plotted as diametral stain vs. equivalent stress times dose [18, 19].

The carbide-induced densification can have other significant consequences. Long components

such as tie rods can shorten by densification, increasing the preload significantly, even under

thermal aging. Calculations of creep-induced relaxation must therefore include the effect of early

load increases. However, even shorter components such as baffle-former bolts may be subject to

early overloading arising from carbide formation [7]. This process has been described by the

original authors as an incubation or threshold period that precedes the onset of creep [18-20],

but this description might be misleading. Note in Figure 3 (right) that the offset of the data to

higher dpa levels might be described equally well by assuming that bolt preloads were increased

by densification at low dpa. Additionally, the scatter in this data set is large and may reflect the

combined effects of densification, stress relaxation and bolt reloading by void swelling [21].

Fig. 3 (left) Unbolting torques measured during removal of bolts from three EDF CP0 plants,

with comparison to relaxation predictions based on upper (solid red) and lower (green) preload

values, assuming a threshold creep model [20]. The dashed red line suggests an alternate

interpretation of carbide-induced load increases. (right) Schematic showing how swelling can

reload a relaxed or replaced bolt, producing a wider range of loads appearing as data scatter [21].



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2.0 Changes in physical properties arising from swelling and precipitation

Very shortly after the discovery of swelling there were a number of efforts made in the USA to

measure swelling using techniques that did not involve microscopy or density change [22-24].

All of these studies were performed on thin (~1 mm) plate specimens from EBR-II hex-thimbles

and produced the same general conclusion that decreases in elastic modulii could be correlated

with density change. The most enlightening of these studies was conducted by Trantow [23] as

shown in Fig. 4. Using an acoustic technique involving multiple internal reflections to effectively

increase the thickness of the specimen, it was shown that all of the elastic modulii decreased

roughly 2% per 1% of density change. Balachov and coworkers later reanalyzed the data to

produce more accurate estimates of these decreases, which varied from 1.98 to 2.66% per 1%

density change, depending on the individual modulus [25]. Poison's ratio was found to be

effectively independent of swelling.

Fig. 4 Compilation of data showing decreases in elastic modulii of 304 stainless steel control rod

thimble as a function of neutron-induced density decrease, as re-evaluated by Balachov [24,25].

Absolute values for all modulii and Poisson's ratio are shown on the left, and the change in value

of Young's modulus on the right. Also shown on the lower right is a micrograph of another 304

stainless steel reflector thimble with a mixture of voids and small finely-dispersed M23C6 carbide

precipitates, with ~1% void swelling reached at 380°C and 21.7 dpa [2,26].



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At the time of Trantow's study, however, the impact of carbide precipitates to alter both the alloy

density and the elastic modulii was not fully appreciated. Therefore, these results must be

recognized as being not fully extrapolatable to other 304 heats or 300 series steels, especially

those having differences in carbon level. Note the very high density of carbides shown in Fig. 4.

Whereas the earlier USA studies focused only on acoustic techniques, Balachov and coworkers

examined a variety of other physical properties and measurement techniques (e.g., eddy current,

electrical resistivity) using disks cut from reflector assembly thimbles, but found that some

techniques were not very applicable due to a ferrite layer that had formed on the thimble surface

[25, 27]. The conclusion regarding the applicability of ultrasonic measurements to estimate the

void swelling was confirmed however. Once again, however, there was no data in these studies

that allow separation of the void and precipitate contributions to ultrasonic velocity.

Fig. 5 Change in ultrasonic time-of-flight measured in thin (~1 mm) circular disk sections of 304

stainless steel reflector thimbles as a function of density change [25,27]. Also shown is the exit

side of one typical disk punched from the thimble. Note the indications of a torn-away layer

around the edges, later found to be a uniform surface ferrite layer that had formed as a

consequence of radiation-assisted leaching of Ni and Mn into the flowing sodium coolant.

Electrical resistivity has been used successfully to measure and separate the combined influence

of void swelling and transmutation products in copper, an element which transmutes sufficiently

to affect resistivity [28-30], but stainless steels in most nuclear spectra do not transmute

sufficiently to affect most physical properties [1,31]. Sagisaka demonstrated that changes in

electrical resistivity could be correlated with swelling in a model austenitic alloy, but noted that

segregation and precipitation could dominate the resistivity change at low dpa levels [6].

Some Russian studies examined electrical resistivity as a tool for assessing swelling in addition

to ultrasonic velocity, and applied the technique to austenitic fuel pin cladding which is more

challenging geometry than flat plates cut from thimbles. Figure 6 (left) shows an early,

previously unpublished, Russian example of a fuel pin cladding tube measured with fuel still

inside, compared with measurements on 20 mm cladding sections cut and cleaned prior to

measurement. Note there is very good agreement with swelling measured by density change, but

the cleaned specimens exhibit much less scatter. While the resistivity changes are roughly +1%

per 1% swelling as expected from theory [3-5], the two modulii change in the opposite direction

and are roughly twice as large. The rates of change in shear and Young's modulii also differ

somewhat as seen in Trantow's study. Measurement of modulii while the fuel pin was still intact

was not as successful when compared to the success attained using resistivity, and no results are



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shown. Measurements made on one of the spacer wires from this assembly are shown in Fig. 6

(right).

Fig. 6 (left) Relative changes in swelling, electrical resistivity and elastic modulii observed on

the cladding along the length of a fuel element irradiated in the BN-600 fast reactor. (right)

Electrical resistivity change (red) and swelling (black) observed along a spacer wire constructed

of another steel (0.1C-16Cr-15Ni-3Mo-1Nb) [5].

Fig. 7 Relative changes along the length in physical and mechanical properties of two pins

from one fuel assembly, one peripheral pin (left) and one central fuel pin cladding made of 20%

cold-worked ChS-68 [5, 32], where S is swelling measured by density change, R is the change in

electrical resistance and E is the change in Young's modulus.

In Figs. 7 and 8 are shown the results of measurements on fuel cladding specimens that were cut

from peripheral and central fuel elements of one subassembly irradiated in the BN–600 reactor.

The claddings were made of cold-worked (20%) "ChS-68" (0.1C-16Cr-15Ni-2Mo-2Mn-Ti-Si)

stainless steel. The peripheral fuel element reached a maximum of 69 dpa and the central one

reached 72 dpa, with the latter operating at somewhat higher temperatures. Because of the

combined effect of slightly higher dose and somewhat higher temperatures the maximum

swelling was significantly higher in the central pin. [5, 32].

300 350 400 450 500 550 6000

5

10

15

32 dpa45 dpa

28 dpa

35 dpa

43 dpa

46 dpa

Re

lati

ve

ch

an

ge

(%

)

Temperature (0C)

-25

-20

-15

-10

-5

0

5

10

15

-500 0 500 1000

Coordinate in the direction from the bottom of the core, mm

Rel

ati

ve

cha

ng

es in

th

e P

M p

rop

erti

es,

%

S R E

-25

-20

-15

-10

-5

0

5

10

15

-500 0 500 1000

Coordinate in the direction from the bottom of the core, mm

Rel

ati

ve

chan

ges

in

th

e P

M p

rop

erti

es,

%

S R E



8

Fig. 8 Relative changes as a function of swelling in electrical resistivity R and Young's modulus

E of both the peripheral and central fuel pin cladding made of 20% cold-worked ChS-68 [5],

Note that the divergence from void-based predictions (solid lines) varies with the property

measured and the temperature range, with the greatest effect observed at higher temperatures in

the electrical resistivity [5,32].

Note that the relative relationship of the properties varies not only between the two data sets but

also as a function of position along the pin. This behavior is suggestive of the varying amounts

and varying identity of precipitation as a function of dose and temperature. This steel has a

number of phases including various carbides with TiC dominating at lower temperatures and

doses and G-phase dominating at higher temperatures. Examples are shown in Fig. 9.

Fig. 9 Variation in precipitation observed in the central fuel pin cladding of ChS-68 as a function

of dose and especially temperature [5].

Also, as seen in Fig. 8 (left), there is an increasing divergence at higher temperatures between the

relative magnitude of swelling and resistivity change, again possibly reflecting a change in



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precipitation behavior with resultant influence on electrical resistivity. It appears that

precipitation effects on both electrical resistivity and elastic modulii can vary with alloy, dpa and

dpa rate, irradiation temperature and the property change measured.

3.0 How best to separate the contributions arising from voids and precipitation?

It appears from the data above that the precipitation effect is more prominent in more complex

alloys with a greater range of precipitation. Therefore for a first attempt it is best to focus on a

simpler alloy, namely 304 stainless steel which is subject primarily only to carbide formation,

especially M23C6. It also appears that in general the precipitate influence on the elastic properties

is less pronounced than in the electrical resistance, so we will focus first on ultrasonic velocity.

In previous papers we described the examination of two hexagonal blocks of 304 stainless steel

that were removed from a stack of five blocks (52 mm from one hex face to opposing face, with

variable lengths, all at 240 mm or less) residing inside of a reflector assembly irradiated outside

the EBR-II fast reactor core, experiencing dpa rates characteristic of PWR internals [33,34].

As shown in Fig. 10, the blocks were labeled 1 to 5 with increasing elevation, with damage dose

rate and gamma heating rate highest in the middle of Block 3. Four of these five blocks (#2-5)

were subjected to non-destructive examination, and two of these (#3 and #5) were committed to

extensive destructive examination thereafter. Measurement techniques employed were non-

destructive profilometry and ultrasonic time-of-flight, the latter to map the internal distribution

of through-thickness average swelling. Following cutting of the blocks into successively smaller

pieces, additional ultrasonic time-of-flight measurements were made, as well as bulk density and

void swelling measurements, the latter using electron microscopy. Over the stack there were

significant axial and radial gradients in both dose and temperature, with gamma heating acting to

cause significant internal temperature increases, producing a complex spatial distribution of void

swelling within the block ensemble.

Fig. 10 Schematic showing two hexagonal blocks (304 stainless steel) chosen for ultrasonic examination

that have very different swelling distributions, but essentially the same carbon removal, allowing

separation of void and precipitate contributions to changes in ultrasonic velocity.



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While profilometry measurements of block 3 clearly showed swelling dominating to produce an increase

in face-to-face dimension, it was also clear that block 5 had experienced a decrease in these dimensions

[33,34] and it was clear from density measurements that Block 5 had densified [35]. When time-of-flight

ultrasonic measurements were made from face-to-face it was clear that block 3 had indeed swollen and

block 5 had significantly contracted in thickness. The ultrasonic techniques employed in this study are

described in refs. [36-38].

Fig. 11 Ultrasonic time-of-flight measurements made from three sets of opposing faces of blocks 3 and 5,

showing void swelling and carbide precipitation producing changes in ultrasonic velocity [33,34].

Swelling in block 3 micrographs are a) 1.84, b) 2.76 and c) 1.95% at varying depths from the face mid-

center on a 28 dpa iso-dose trace. Block 5 had much smaller amounts of swelling but similar carbides.

5800

5780

5760

5740

5720

5700

5680

5660

Velocity(m/s)

20015010050

Position(mm)

Flat1-4 of Block3 Flat2-5 of Block3 Flat3-6 of Block3 Archive material



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After face-to-face measurements were made the blocks were cut into 2.5 cm thick hex-coins. Time-of-

flight measurements were made across the cut-faces of the coin, producing swelling distribution maps that

reflected the off-center but almost symmetrical swelling in block 3, a conclusion deduced earlier from

profilometry measurements. Block 5 had much smaller variations, reflecting lower doses and lower

gradients in both dose and temperature.

Fig. 12 Typical distributions of ultrasonic velocity measured in block 3. Two of the five hex-coins are

shown [33,34].

Figure 13 Distributions of ultrasonic velocity observed at top of block 5 (~0.3 dpa, left) and bottom of

block 5 (~4 dpa, right) [33,34]. At the top of the block the variations in temperature and displacement

dose are very small, producing very small variations in swelling and carbide distribution.



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Based on these data and additional data contained in references [33-37], it was possible to extract the

relative contributions of voids and precipitates to the ultrasonic velocity, at least for this alloy. Thus it is

possible to modify our understanding of the factors that determine the velocity, as shown below.

As shown in the equation above, the ultrasonic velocity is determined by decreases of 2.5% per 1% void

swelling and increases of 3.5% per 1% carbide volume. The apparently large value for precipitation is put

into better context when it is noted that the carbide volume is not very large.

While the time-of-flight method used in this study provides an average swelling over the thickness of the

specimen, it appears to be possible to determine the depth dependence of swelling using more advanced

ultrasonic techniques involving back-scatter of ultrasonic waves off of the voids and precipitates [36-39].

More work is required to develop this opportunity, especially for application to in-situ swelling

measurement in PWR cores.

CONCLUSIONS

It has been demonstrated in this paper that there are competing influences of void swelling and precipitate

formation during irradiation of austenitic stainless steels that determine not only dimensional changes, but

also changes in physical properties. Precipitation to the first order can lead to measurable changes in

lattice parameter and alloy density, and thereby produce measureable strains, positive or negative, that

can complicate the extrapolation of low dose data to higher doses. Precipitation may also lead to

significant changes in preloads of tie rods and baffle-former bolts and can camouflage the onset of void

swelling.

To the second order, precipitation can also contribute to changes in physical properties such as elastic

modulii and electrical resistivity. Use of such physical properties to accurately measure swelling non-

destructively requires that the relative contributions of void swelling and precipitation be separated, but

the contributions appear to be very sensitive, not only to alloy composition, but also to the details of the

reactor environment, especially the temperature and dpa damage rate.

It is possible under some conditions to conduct such a separation and in this paper we have provided one

example of an experimental path that can achieve this goal that employed ultrasonic time-of-flight

techniques. Ultrasonic techniques appear to work best on relatively thick components where the flight

path is relatively long. For thinner components such as cladding electro-resistive techniques may work

better.



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REFERENCES

[1] F.A. Garner, "Radiation Damage in Austenitic Steels", in Konings, R.J.M., (ed.)

Comprehensive Nuclear Materials, Volume 4, (2012) pp. 33-95, Elsevier.

[2] F. A. Garner, Chapter 10, "Void swelling and irradiation creep in light water reactor

(LWR) environments", in Understanding and Mitigating Ageing in Nuclear Power Plants,

Ed. P. G. Tipping, Woodhouse Publishing, 2010, pp.308-356.

[3] W. G. Wolfer and F. A. Garner, "Effective Thermophysical and Elastic Properties of

Materials with Voids", DAFS Quarterly Progress Report No. 25 (May 1984) DOE/ER-

0046/17, p. 58.

[4] I. I. Balachov, E. N. Shcherbakov, A. V. Kozlov, I. A. Portnykh and F. A. Garner,

“Influence of Irradiation-Induced Voids and Bubbles on Physical Properties of Austenitic

Structural alloys, “J. Nucl. Mater., 329-333 (2004) 617-620.

[5] A. V. Kozlov, E. N. Shcherbakov, S. A. Averin and F. A. Garner, “The Effect of Void

Swelling on Electrical Resistance and Elastic Moduli in Austenitic Steels,” Effects of

Radiation on Materials, ASTM STP 1447, M. L. Grossbeck, T. R. Allen, R. G. Lott and

A. S. Kumar, Eds., ASTM International, West Conshohocken PA, 2004, pp. 66-77.

[6] M. Sagisaka, Y. Isobe, F. A. Garner, S. Fujita and T. Okita, "Development of

Nondestructive Inspection Techniques for Measurement of Void Swelling in Irradiated

Microscopy Discs", Nucl. Mater., 417 (2011) 992-995.

[7] F. A. Garner, W. V. Cummings, J. F. Bates and E. R. Gilbert, "Densification-Induced

Strains in 20% Cold-Worked 316 Stainless Steel During Neutron Irradiation," Hanford

Engineering Development Laboratory, HEDL-TME-78-9, June 1978.

[8] F. A. Garner, Chapter 6: "Irradiation Performance of Cladding and Structural Steels in

Liquid Metal Reactors," Vol. 10A of Materials Science and Technology: A

Comprehensive Treatment, VCH Publishers, 1994, pp. 419-543.

[9] R. J. Puigh, A. J. Lovell and F. A. Garner, "Thermal Creep and Stress-Affected

Precipitation of 20% Cold-Worked 316 Stainless Steel," J. Nucl. Mater., 122-123 (1984)

242-245.

[10] J. L. Straalsund and J. F. Bates, "Partial molar volumes and size factor data for alloy

constituents of stainless steel", Met. Trans. 5 (1974) 493-498.

[11] F. A. Garner, H. R. Brager, R. A. Dodd and T. Lauritzen, Ion-induced spinodal-like

decomposition of Fe-Ni-Cr Invar alloys", Nuclear Instruments and Methods in Nuclear

Research B16, (1986) 244-250.

[12] F. A. Garner and J. M. McCarthy, "Spinodal-Like Decomposition of Fe-Ni and Fe-Ni-Cr

"Invar" Alloys During Neutron or Ion Irradiation," in Proceedings of TMS Symposium

on Physical Metallurgy of Controlled Expansion Invar-Type Alloys, February 27-March

3, 1989, Las Vegas, NV, pp. 187-206.

[13] F. A. Garner, J. M. McCarthy, K. C. Russell, and J. J. Hoyt, "Spinodal-Like

Decomposition of Fe-35Ni and Fe-Cr-35Ni Alloys during Irradiation or Thermal Aging,"

J. Nucl. Mater., 205 (1993) 411-425.



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[14] K. V. Tsay, O. P. Maksimkin, L. G. Turubarova, O. V. Rofman, F. A. Garner, "

Microstructural defect evolution in neutron-irradiated 12Cr18Ni9Ti stainless steel during

subsequent isochronous annealing", J. Nucl. Mater., 439 (2013) 148-158.

[15] K. J. Irvine, D. T. Llewellyn and F.B. Pickering, J. Iron Steel Institute 199 (1961) 153-175.

[16] G. R. Gessell, "Effects of minor alloying additions on the strength and swelling of an austenitic

stainless steel", Oak Ridge National Laboratory Report ORNL/TM 6359, June 1978.

[17] J. F. Bates, M. M. Paxton and J. L. Straalsund, "Effects of minor alloy variations on the thermal

densification of austenitic stainless steels", Nucl. Tech. 20 (1973) 134-135.

[18] P. Dubuisson, J.P. Massoud, N. de Mathan, V. K. Shamardin, V. I. Prokhorov, V. N. Golovanov,

"Behaviour under neutron irradiation of austenitic stainless steels (representative of French core

internals) irradiated in BOR-60 and SM reactors", Proceedings of 6th Russian Conference of

Reactor Material Science, (2000) Vol. 1, pp. 128-145.

[19] J. Garnier, P. Dubuisson, M. Delnondedieu, J.P. Massoud, Y. Bréchet, "Irradiation creep of SA

304L and CW 316 austenitic stainless steels representative of the French core internals",

Proceedings of 8th Russian Conference of Reactor Material Science, (2007).

[20] E. Lemaire, J.-P. Massoud and N. Ligneau, "Ageing management of reactor vessel internals in

EDF PWRs", Proc. Intern. Symp. Fontevraud VII, SFEN, 2010, paper no. A153 T02.

[21] E. P. Simonen, F. A. Garner, N. A. Klymyshyn and M. B. Toloczko, “Response of PWR Baffle-

Former Bolt Loading to Swelling, Irradiation Creep and Bolt Replacement as Revealed Using

Finite Element Modeling”, in proceedings of 12th International Conference on Environmental

Degradation of Materials in Nuclear Power Systems - Water Reactors, 2005, pp.449-456.

[22] M. Marlowe and W. K. Appleby, “Measurements of the Effects of Swelling on the Young’s

Modulus of Stainless steels,” Trans. Amer. Nucl. Soc., 16 (1973), 95.

[23] J. L. Straalsund and C. K. Day, “Effect of Neutron Irradiation on the Elastic Constants of Type-

304 Stainless Steel,” Nucl. Tech., 20 (1973) 27.

[24] R. L. Trantow, “Ultrasonic Measurement of Elastic Properties in Irradiated 304 Stainless Steel,”

HEDL-1ME-73-92, 1973.

[25] I. Balachov, F. A. Garner and Y. Isobe, "In-Situ NDT Measurements of Irradiation-Induced

Swelling in PWR Core Internal Components, Phase 3: Correlation of Void Swelling and Material

Properties of Austenitic Steels, EPRI, Palo Alto, CA: 2003.

[26] G. M. Bond, B. H. Sencer, F. A. Garner, M. L. Hamilton, T. R. Allen and D. L. Porter, “Void

Swelling of Annealed 304 Stainless Steel at ~370-385C and PWR-Relevant Displacement

Rates”, 9th International Conference on Environmental Degradation of Materials in Nuclear

Power Systems – Water Reactors, 1999, pp. 1045-1050.

[27] I. Balachov, F. A. Garner, Y. Isobe, M. Sagisaka and H. T. Tang, “NDT Measurements of

Irradiation Induced Void Swelling,” 11th International Conference on Environmental

Degradation of Materials in Nuclear Power Systems – Water Reactors, 2003, pp. 640-646.

[28] F. A. Garner, H. R. Brager and K. R. Anderson, "Neutron-Induced Changes in Density

and Electrical Conductivity of Copper Alloys at 16 to 98 dpa and 430ºC", J. Nucl. Mater.,

179-181 (1991) 250-253.

[29] L. R. Greenwood, F. A. Garner and D. J. Edwards, "Calculation of Transmutation in Copper and

Comparison with Measured Electrical Properties", Proc. Eighth ASTM-Euratom Symposium on

Reactor Dosimetry, Vail, CO. Aug 29-Sept 3, 1993, ASTM STP 1228, pp. 500-508.



15

[30] D. J. Edwards, F. A. Garner, and L. R. Greenwood, "Influence of Transmutation, Void Swelling

and Flux/Spectra Uncertainties on the Electrical Properties of Copper and Copper Alloys," J.

Nucl. Mater., 212-215 (1994) 404-409.

[31] J. F. Bates, F. A. Garner and F. M. Mann, "The Effects of Solid Transmutation Products

on Swelling in AISI 316 Stainless Steel," J. Nucl. Mater. 103-104 (1981) 999.

[32] О.V. Ershova, Е.N. Shcherbakov, М.V. Evseev, P.I. Yagovitin, V.S. Shikhalev, А.V. Kozlov, F.

A. Garner, " Correlation of changes in physico-mechanical properties with swelling of the "ChS-

68" austenitic steel under high dose irradiation", manuscript in preparation for submission to J.

Nucl. Mater.464 (2015) 516-530.

[33] F. A. Garner, T. Okita, Y. Isobe, J. Etoh, M. Sagisaga, T. Matsunaga, P. D. Freyer, Y. Huang,

J.M.K. Wiezorek, D. L. Porter, "Measurement of depth-dependent swelling in thick non-uniform

irradiated 304 stainless steel blocks using non-destructive ultrasonic techniques", Proceedings of

Fontevraud 8 - Contributions of Materials Investigations and Operating Experience to LWR's

Safety, Performance and Reliability, Avignon, France, 2014.

[34] F. A. Garner, P. D. Freyer, D. L. Porter, J. Wiest, C. Knight, T. Okita, M. Sagisaka, Y. Isobe, J.

Etoh, T. Matsunaga, Y. Huang, J. Wiezorek, “Void swelling and resultant strains in thick 304

stainless steel components in response to spatial gradients in neutron flux-spectra and irradiation

temperature”, Proceedings of 16th International Conference on Environmental Degradation of

Materials in Nuclear Power Systems - Water Reactors.

[35] Y. Huang, J.M.K. Wiezorek, F.A. Garner, P.D. Freyer, T. Okita, M. Sagisaka,Y. Isobe, T.R.

Allen, "Microstructural characterization and density change of 304 stainless steel reflector blocks

after long-term irradiation in EBR-II", J. Nucl. Mater.

[36] J. Etoh, M. Sagisaka, T. Matsunaga, Y. Isobe, F. A. Garner, P. D. Freyer, Y. Huang, J. M. K.

Wiezorek, T. Okita, "Development of a nondestructive inspection method for irradiation-induced

microstructural evolution of thick 304 stainless steel blocks", J. Nucl. Mater., 440 (2013) 500-

507.

[37] Y. Isobe, J. Etoh, M. Sagisaka, T. Matsunaga, P. D. Freyer, F. A. Garner, T. Okita, “Using UT to

assess neutron-induced damage”, Nuclear Engineering International, April 24, 2014, 36-39.

[38] T. Okita, J. Etoh, M. Sagisaka, T. Matsunaga, Y. Isobe, P. D. Freyer, J. M. K. Wiezorek, F. A.

Garner, "Validation of ultrasonic velocity measurements in first wall structural materials", Fusion

Science and Technology 66 (2014) 77-82.

[39] J. Etoh, M. Sagisaka, T. Matsunaga, Y. Isobe, T. Okita, "A simulation model of ultrasonic wave

changes due to irradiation-induced microstructural evolution of thick 304 stainless steel blocks",

J. Nucl. Mater. 441 (2113) 503-507.

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The competing influences of void swelling and radiation ...envdeg2015.org/final-proceedings/ENVDEG/papers/ENVDEG021.pdf · the two competing effects in order to develop fully-predictive