ML20210B420

Thermal Diffusivity of H-451 Graphite & Temp Monitor Analyses in Fort St Vrain Fuel Test Element FTE-2

ML20210B420
Person / Time
Site:	Fort Saint Vrain
Issue date:	08/22/1986
From:	GENERAL ATOMICS (FORMERLY GA TECHNOLOGIES, INC./GENER
To:
Shared Package
ML20210B388	List: ML20210B382 ML20210B420
References
TAC-62026, NUDOCS 8609180071
Download: ML20210B420 (30)

Text

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a Thennal Diffusivity of H-451 Graphite and Temperature Monitor Analyses in Fort St. Vrain Fuel Test Element FTE-2 e

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Prepared by GA Technologies Inc.

for Public Service Company of Colorado August 22, 1986 i

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ISSUE

SUMMARY

l TITLE THERMAL DIFFUSIVITY OF H-451 GRAPHITE AND O R&D APPROVAL LEVEL 1

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TEMPERATURE MONITOR ANALYSES IN FSV FUEL GDV&S TEST ELEMENT FTE-2 O DESIGN DISCIPLINE SYSTEM 00C. TYPE PROJECT l 0OCUMENT NO.

ISSUE N0/LTR.

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18 RTE 1900 I

508928 N/C I

QUALITY ASSURANCE LEVEL SAFETY CLASSIFICATION SEISMIC CATEGORY ELECTRICAL CLASSIFICATION I

N/A N/A N/A APPROVAL ISSUE

^

ISSUE DATE DESCRIPTION /

BY FUNulNG APPLICABLE

, ENGINEERING DA CWBS NO.

PROJECT PROJECT l

. i' p'2 6 6 /d ( dh dC%{.L' Nicolaye ff N/C AUG 2 21986 F.'McCord' O. M., af,' I ' ~ ^ *F

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. s TITLE: THERMAL DIFFUSIVITY OF H451 GRAPHITE D0C. NO. 908928

'AND TEMPERATURE MONIIOR ANALYSIS IN ISSUE N/C FSV FUEL ELEMENT FTE_2 TABLE OF CONTENTS 1.0

SUMMARY

AND CONCLUSIONS.

6 2.0 LOCATION OF SPECIMENS.

7 2.1 Thermal Diffusivity 7

2.2 Silicon Carbide Temperature Monitors.

7 3.0 EXPERIMENTAL METHODS 8

3.1 Thormal Diffusivity 8

3.2 Silicon Carbide Temperature Monitors.

9 4.0 RESULTS.

11 4.1 Thermal Diffusivity 11 4.2 Silicon Carbide Temperature Monitors 11 5.0 DIECUSSION 13 5.1 Thermal Diffusivity 13 5.2 Silicon Carbide Temperature Monitors.

13

6.0 REFERENCES

15 f ;

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TITLE: THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908928 AND TEMPERATURE MONITOR ANALYSIS IN

. ISSUE N/C FSV FUEL ELEMENT FTE.2 LIST OF TABLES 1

TABLE 1 - GRAPHITE TEMPERATURES INDICATED BY 16 SILICON CARBIDE TEMPERATURE MONITORS TABLE 2 - COMPARISON BETWEEN MEASURED AND PREDICTED PROPERTY.

17 VALUES FOR H-451 GRAPHITE FROM FTE-2 ASSUMING AN IRRADIATION TEMPERATURE OF (A) 510 C AND (B) 650 C (FLUENCE = 1.6 X 10 n/cm, E)0.18 Mev) 4 t

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TITLE: THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908928 mw mus.nnivas, nvauva ANALTSIG IN ISSUE N/C FSV FUEL ELEMENT FTE-2 d

LIST OF FIGURES FIGURE 1 - CORE POSITIONS-(LAYER 6) SHOWING LOCATION.

18 OF EIGHT TEST ELEMENTS FIGURE 2 - LOCATION OF TEST SLAB IN FUEL ELEMENT.

19 FIGURE 3 - RADIAL POSIT 0N OF MONITORS 20 FIGURE 4 - MONITOR AND FUEL ASSEMBLY,....

21 FIGURE 5 - SCHEMATIC DIAGRAM OF MONITORS USED IN FSV FUEL 22 TEST ELEMENTS FIGURE 6 - SCHEMATIC OF INFRARED DETECTOR AND ASSOCIATED.

.23 OPTICS FOR THE HIGH TEMPERATURE THERMAL DIFFUSIVITY APPARATUS FIGURE 7 - THERMAL CONDUCTIVITY OF UNIRRADIATED POCO AXF-SQ..

24 GRAPHITE.

1983 GA MEASUREMENTS AND LITERATURE DATA SHOWN FOR COMPARISON FIGURE 8 - THERMAL CONDUCTIVITY OF IRRADIATED H-451 GRAPHITE 25 i

FROM FTE-2 FIGURE 9 - THERMAL CONDUCTIVITY OF IRRADIATED H-451 GRAPHITE 26 FROM FACE A 0F FTE-2 SHOWING THE EFFECT OF ANNEALING

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TO ~850 C FIGURE 10 - PLOT OF LENGTH CHANGE VERSUS ANNEALING TEMPERATURE.

27 FOR MONITORS H131M4, H239M4, AND H307M1 4

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TITLE: THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908928 AND TEMPERATURE MONITOR ANAIlfSIS IN ISSUE N/C FSV FUEL ELEMENT FTE-2 FIGURE 11 - PLOT OF LENGTH CHANGE VERSUS ANNEALING TEMPERATURE,. 28 FOR MONITORS H18M1, H59M3, AND H67M1 FIGURE 12 - THERMAL CONDUCTIVITY OF H-451 GRAPHITE FROM FTE 2

. 29 i

COMPARED WITH DESIGN CURVE FOR 1.6 X 10 n/cm (E)0.18 Mev) AT 650 C

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TITLE: THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908928 AND TEMPERATURE MONITOR ANALYSIS IN ISSUE N/C FSV FUEL ELEMENT FTE-2 1.0

SUMMARY

AND CONCLUSIONS Fuel test element FTE-2 (H-451 graphite, Lot 426) from the Fort St. Vrain (FSV) Nuclear Generating Station was destructively examined at GA Technologies Inc. (GA) during the first half of 1986. Figure 1 shows the core location of FTE-2.

A report describing most of the test data was issued (Ref. 1).

At the time the report was written, the following two series of tests were incomplete:

1 1.

Measurement of the thermal diffusivity of graphite specimens cored from the test element.

2.

Analysis of the silicon carbide ps.ssive temperature monitors from the monitor packages.

These tests have now been completed and this report gives the results.

Thermal conductivities from the thermal diffusivity measurements fell in the range of 30-40 W/m-K, witn only a small dependence on measurement temperatures and no systematic dependence on the face from which the cores were taken.

The silicon carbide temperature monitors indicated temperatures ranging from 650 C at the top of the block to 710 C at the bottom of the block. A thermal analysis performed for the last 30 effective full-power days of operation using a calculated region peaking fact'or gave calculated temperatures within 10-40 C of the indicated tempera-tures of the silicon carbide monitors. Taking into account experi-mental errors and calculational and modeling uncertainties, the agree-ment between indicated and calculated temperatures is reasonable.

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TITLE: THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908928 AND TEMPERATURE MONITOR ANALYSIS IN ISSUE N/C FSV FUEL ELEMENT FTE-2 In the previous report on FTE 2 (Ref. 1) a time-average graphite temperature of 510 C was assumed when comparing the observed graphite properties with design values. A graphite temperature of about 6'0 C 5

is more consistent with the observed graphite property changes. At 650 C the differences between the measured and predicted values are 10% or less for all properties.

2.0 LOCATION OF SPECIMENS 2.1 Thermal Diffusivity Materia'l for preparing thermal diffusivity specimens was taken from a 7 inch deep slab located in the test element as shown in Fig.

2.

Buttons located as shown in Fig. 2 were cored from four of the six faces of the slab (faces A, B, E and F).

Two or three disc-shaped specimens were machined from each button. The specimen dimensions were 0.375 in. diameter x 0.08 in. thick. The heat flow direction in the tests was in the radial direction of the fuel test' element.

One-specimen from each button (three specimens from each face) was tested.

2.2 Silicon Carbide Temperature Monitors Temperature monitors from the following monitor packages were measured:

Hole 18 monitor #1 (H18 M1)

Hole 59 monitor #3 (H59 M3)

Hole 67 monitor #1 (H67 M1)

Hole 131 monitor #4 (H131 M4)

Hole 239 monitor #4 (H239 M4)

Hole 307 monitor #1 (H307 M1) 7-

TITLE: THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908928 AND TEMPERATURE MONITOR ANALYSIS IN ISSU'E N/C FSV FUEL ELEMENT FTE-2 The first part of the reference number identifies the fuel hole in which the monitor package was located, as shown in Fig 3.

The monitor packages partially replaced fuel rods in the stack as shown in Fig. 4.

Reference numbers with M1 identify monitors placed at the top of the fuel hole; those with M3 or M4 refer to monitors placed at approxi-mately one-third of the height of the fuel stack or at the bottom of the fuel stack, respectively. The placement.of the silicon carbide monitor within the package is shown in Fig. 5.

3.0 EXPERIMENTAL METHODS All test data and methods relating to the thermal diffusivity and temperature monitor analyses for FTE-2 are recorded in GA laboratory book number 8666.

3.1 Thermal Diffusivity The specimens were measured by the transient heat pulse method.

The-front surface of the specimen was exposed to a heat pulse from a ruby laser while the temperature of the back surface was monitored with an infrared detector. Figure 6 shows a schematic diagram of the infrared optics and associated equipment. The transient temperature response of the back surface is displayed on the screen of a digitiz-ing oscilloscope. The elapsed time after the laser triggering pulse to the time when the temperature reaches half its anximum value, t1/2' is measured from the oscilloscope display. When the heat pulse is short compared to t1/2, the thermal diffusivity,oc, can be calculated from t and the specimen thickness, /, by the expression:

1/2 gq,0.139/

(1)

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i TITLES-THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC, NO. 908928 AND TEMPERATURE MONITOR ANALYSIS IN ISSUE N/C FSV FUEL ELEMENT FTE-2 The thermal conductivity can be calculated by multiplying the thermal diffusivity by the density and the specific-heat. Specific heat

-values as a function of temperature were taken from the literature (Ref. 2).

Other details of the method are given in Ref. 3.

The specimens were tested in a helium atmosphere. The specimen temperature was raised'to 700 C at approximately 20 C/ minute.

Measurements were started at about 250 C; at lower temperatures the response of the infrared detector is inadequate for accurate measure-ments. Measurements were taken at approximately 50 C intervals. A few additional measurements were taken during cool-down.to verify that no annealing or property changes had taken place due to the time spent at the higher temperature.

3.2 Silicon' Carbide Temperature Monitors When irradiated silicon carbide specimens are subjected to a series of isochronal anneals at temperatures increasing in increments of 25-50 C, a plot of the length (measured.at room temperature) versus annealing temperature shows a fairly abrupt change of slope at the irradiation temperature.

In the case of specimens irradiated at vary -

l ing temperatures, the change of slope indicates the temperature during

~

20 2

the final ~10 n/cm of irradiation. This method is reliable for irradiation temperatures between 300 and 900 C.

By fitting two straight lines through the first and second parts of the curve, the intersection of the two lines coincides with the irradiation tempera-ture with an accuracy of 20-30 C (Ref. 4).

Since a long series of isochronal anneals with intermediate length measurements'is very time-consuming, an alternative method consists of recording the specimen j

length as a function of temperature in a conventional dilatometer, using a low constant heating rate.

If the specimen is then re-heated in the dilatometer after cooling from the maximum temperature, the i

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_ TITLE: THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908928 AND TEMPERATURE MONITOR ANALYSIS IN ISSUE N/C FSV FUEL ELEMENT FTE-2 j-l difference between the first and second length versus temperature curves can be used to construct a plot equivalent to a standard length versus annealing temperature curve.

Plots of this type were reported in Reference 5 for silicon carbide specimens irradiated at 500 C.

The change in slope of the curves was less well defined than for the isochronal annealing method. However, if length change and temperature points from Reference 5 are read off the curve starting about 50 C above the point of the first deviation from the baseline and used to plot a straight line, the temperature of intersection with the baseline agrees well with the irradiation temperature.

The dilatometer method was used to analyze the silicon carbide monitors from FTE-2.

The specimens were heated in a silica dilato-meter in a helium atmosphere at a rate of 1 C/ minute.

The maximum temperature was 950 C.

After reaching 950 C the specimens were allowed to furnace-cool in the dilatometer to about 200 C and then

-they were re-heated at 3 C/ minute. The specimen length was recorded continuously. The specimen length changes resulting from annealing during the first heating cycle were obtained from the difference between the first and second heating curve. As a check length changes were also measured from the difference between the first heating curve and the cooling curve.

l The length change data were analyzed by linear ~ regression analysis of the length change versus temperature points. The points used for the linear regression analysis were taken at 50 C intervals starting about 50 C above the temperature where deviation from the baseline was first noted.

The temperature of intersection of the linear regres-sion line with the baseline was calculated, together with the 90%

confidence interval for the intersection temperature.

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TITLE: THERMAL DIFFUSIVITY OF H451 GRAPHITE D0C. No. 908928 AND TEMPERATURE MONITOR ANALYSIS IN ISSUE N/C FSV FUEL ELEMENT FTE-2 4.0 RESULTS 4.1 Thermal Diffusivity As a check on the accuracy of the transient heat pulse method, a specimen of POCO AXF-SQ graphite 0.108 in, thick was measured at temperatures between 200 C~and 700 C.

Figure 7 shows the thermal conductivity values as a function of temperature, with 1983 GA measurements and literature data on POCO graphite shown for comparison (Ref. 6).

The agreement is satisfactory.

Figure 8 shows the measured thermal conductivity of'the irradiated specimens from FTE-2 as a function of measurement temperature.

For converting the thermal diffusivity to thermal conductivity a density of 1.745 g/cm waa used (measured on cylindrical specimens from locations close to the buttons), and literature values for heat capacity were assumed (Ref. 2).

The values fell in the range 30-40 W/m-K with only a small dependence on temperature and no systematic dependence on the face from which the cores were taken.

Measurements taken during cooling were not significantly different from those taken during heat-up, indicating that no annealing had occurred up to 700-750 C.

However, one specimen that was heated to approximately 850 C did show a significantly higher thermal conduc-tivity,' showing that some annealing had taken place. The data are shown in Fig. 9.

4.2 Silicon Carbide Temperature Monitors t

The plots of length change versus temperature are shown in Figs.

10 and 11.

Two sets of points are shown. The first set of points use the cool-down curve as the reference curve and the second set use the

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TITLE:. THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908928 AND TEMPERATURE MONITOR. ANALYSIS IN ISSUE N/C FSV FUEL ELEMENT FTE-2 1

second heating curve as_the reference. There is very little differ-e ence between the two sets of points.

The second set of points was used for the linear regression analysis.

The plots show a reasonably well defined change in'alope, with the exception of the plots for monitors H18 M1 and H67 M1, which show a progressive change in 4

{

' curvature rather than a sharp " knee."

The precision with which the intersection point can be determined is controlled by the slope of the second part of the curve and the scatter of the data points.

Statistical analysis of the data can be used to plac~e confidence limits on a least-squares regression line fitted through these data points. The measurement error is larger when there is curvature (for example, Sample H67M1, Fig. 11) rather than the abrupt change or

" sharp knee" in the slope of the curve (for example, Sample H307M1, Fig. 10).

i j

The temperature where the regression line intersects the baseline provides an estimate of the irradiation temperature. Table 1 lists the intersection temperatures, together with the 90% confidence 1

interval for the estimate. With the exception of monitors H18 M1 and

~

H67 M1, the confidence internals are on the order of + 25 C, which is j

about the expected accuracy for silicon carbide temperature monitors in this temperature range. The indicated temperatures range from approximately 650 C for the M1 monitors (located at the top of the block) to approximately 700 C for the M4 monitors (located at the bottom of the block). As discussed in Section 5.2, the indicated i

temperature is the later graphite irradiation temperature during Cycle 3.

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' THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908928 TITLE AND TEMPERATURE MONITOR ANALYSIS IN ISSUE N/C FSV FUEL ELEMENT FTE-2 5.0 DISCUSSION 5.1 Thermal Diffusivity The measured thermal conductivity of all the specimens is compared in Fig. 12 with a curve calculated from the reference design data used at GA Technologies.- For this curve a fluence of 1.6 x 10 n/cm (E >

0.18 MeV) (Ref. 1) and an irradiation temperature of 650 C (see Section 5.2) were assumed. The data scatter band overlaps the design curve, although on the average the measurements fall about 7% higher than the design curve. For a lower graphite irradiation temperature, the discrepancy would be greater.

5.2 Silicon Carbide Temperature Monitors The temperatures indicated by the silicon carbide temperature monitors (Table 1) show the expected trend of increasing temperature from the top of the fuel element (M1 monitors) to the bottom of the fuel element (M4 monitors). However, the indicated temperatures of 650-700 C are considerably higher than the calculated time averaged block graphite temperature of 510 C discussed in Ref. 1.

The possi-bility of the calculated time average temperature being lower than the indicated temperature was discussed in Reference 1.

Because of this temperature discrepancy, an analysis was performed for FTE-2 in the FSV reactor covering only the last 30 EFPDs* of operation in Cycle 3.

This period corresponds to a fast O

neutron fluence of approximately 1 x 10 n/cm (E > 0.18 Mev), which is about the fluence required for saturation of the irradiation _

4 induced length changes in silicon carbide and also of the thermal conductivity changes in graphite.

Irradiation damage accumulated earlier at different temperatures would have been annealed during this.

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TITLE: THERMAL DIFFUSIY!TY OF H451 GRAPHITE D0C..HO.'908928 AND TEMPERATURE MONITOR ANALYSIS IN ISSUE N/C FSV FUEL ELEMENT FTE-2 period, and the two or three day period of lower power (and tempera-tures) operation just prior to shutdown was too short for significant accumulation of low-temperature _related irradiation damage.

The results indicate that during this last 30 EFPD* period both the silicon carbide monitors and graphite coupon specimens experienced i

significantly higher temperatures than the calculated time averaged block graphite temperature of 510 C..

A thermal analysis with measured region outlet temperatures gave calculated graphite temperatures about 80 C lower than the indicated temperatures in Table 1.

A second analysis using.a calculated region peaking factor I

obtained from fuel accountability analyses gave calculated tempera-tures within 10-40 C of the indicated temperatures.

In Reference 1 a' graphite temperature of 510 C was assumed when comparing the observed tensile properties and thermal expansivity of the graphite with design values. Table 2 shows the effect that a graphite temperature of 650 C would have on the comparison. The table 1,

also includes the thermal conductivity data reported in Section 5.1.

l It is evident from Table 2 that a graphite' temperature of around 650 C I

is more consistent with the observed property changes than is a l

graphite temperature of 510 C.

With a 650 C graphite temperature the differences between the measured and predicted values are 10% or less for all preperties.

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TITLES THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908928 AND TEMPERATURE MONITOR ANALYSIS IN ISSUE N/C FSV FUEL ELEMENT FTE-2

6.0 REFERENCES

1.

McCord, F., " Destructive Examination of Fort St. Vrain Fuel Test Element FTE-2," Document No. 908909, July 11, 1986.

2.

Butland, A.T.D., and R. J. Maddison, "The Specific Heat of Graphite: An Evaluation of Measurements," J. Nucl. Mater..

49, 45 (1973-74).

3.

" Standard Method of Test for Thermal Diffusivity of Carbon and Graphite by a Thermal Pulse Method," ASTM Test Method C-714 (ALTM, Philadelphia, 1983).

4.

Price, R.

J.,

" Annealing Behavior of Neutron - Irradiated Silicon Carbide Temperature Monitors," Nucl. Tehenol.

16.

536 (1972).

5.

Suzuki, H., and T. Tseki, " Annealing Behavior of Neutron Irradiated-sic," J. Nucl. Mater.. 48, 247 (1973).

6.

Taylor, R.

E., and H. Groot, "Thermophysical Properties of POCO Graphite," High Temperatures - High Pressures. 12, 147 (1980).

_ 15 -

TITLE: THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908928 AND TEMPERATURE MONITOR ANALYSIS IN ISSUE N/C FSV FUEL ELEMENT FTE-2 TABLE 1 FTE-2 GRAPHITE TEMPERATURES INDICATED BY SILICON CARBIDE TEMPERATURE MONITORS Data Points Used Indicated 90% Confidence Monitor Number

'in Regression ( C)

Temperature ( C)

Interval ( C) i H18 M1 600-900 640 520-693 H59 M3 650-950 672 631-702 H67 M1 600-950 655 574-703 i

H131 M4 700-950 711 674-738 H239 M4 700-950 710 688-727 r

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TITLE: THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908928 AND TEMPERATURE MONITOR ANALYEIS IN ISSUE N/C FSV FUEL ELEMENT FTE-2 TABLE 2 COMPARISON BETWEEN MEASURED AND PREDICTED PROPERTY VALUES i

FOR H-451 GRAPHITE FROM FTE-2 ASSUMING AN-IRRADIATION TEMPERATURE 0F (A) 510 C AND (B) 650 C (FLUENCE = 1.6 X 10 n/cm, E)0.18 Mev)

Property Orientation Measured T = 510"C T = 650"C Property (1 Std.

Pre-Pre-Dev.)

dicted Dif-dicted Dif-Prop-fer-Prop-fer-erty ence erty ence i

t Tensile Strength, HPa Axial i 24.1 1 3.4 27.0

-11 26.2

-8 Transverse 21.3 1 3.1 21.5

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+2 Young's Modules, GPa Axial 16.7 1 0.4 18.4

-9 17.5

-5 Tre.nsverse 14.5 1 0.6 15.6

-7 14.9

-3 Thermg1,CExpansivity, Axial 3.84 1 0.19 4.48

-14 4.29

-10 10 Transverse 4.55 1 0.08 5.28

-14 5.05

-10 Thermal Conductivity Transverse 33.9 + 2.4 27.4

+24 31.7

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TITLE 2 THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908923

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Fig. 1. Core positions (Layer 6) showing location of eight test eier::ents.

T4TLE: THERMAL DIFFUSIVITY OF H451 GRAPHITE D0C. NO. 508923 AND TEMPERATURE MONITOR ANALYSIS IN ISSUE N/9 FSV FUEL ELEMENT FTE-2

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Removed unfueled cc C-side face

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(typical) l Cores (typical)

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t Fig. 2.

Location of test slab in fuel element

__ - ~ _ _ _, - _ _.. _ - _ -. - -.. _ - _. _ _ - _ _ _ _ -. -. _. _. - -.. - _

TIJLE: THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908923 AND TEMPERATURE MONITOR ANALYSIS IN ISSUE N/C FSV FUEL ELEMENT FTE

---

........._____-2_____________________________________________

h Ho1es with monito s ooOoosooOoo

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g ALL INDICATED 110LE LOCATIONS IIAVE A MINIMUM OF ONE MONITOR AT THE TOP 0F Tile ELEMENT FOR ALL FTEs EXCEPT IIOLE LOCATION 248 IIAS FOUR MONITORS (FO ALL FTEs) AND 110LE LOCATIONS 59, 86,131,194, 239, and 266 EACH IIAVE FOUR MONITORS FOR FTE-2, -4,AND -6.

Fig. 3.

Radial position of monitors.

TLTLE: THERMAL DIFFUSIVI"'Y OF H451 GRAPHITE DCC. NO. 908928 AND TEMPERATURE MONITOR ANALYSIS IN ISSUE N/C

~~

FSV FUEL ELEMENT FTE-2

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- fik >h: 7 x1 I ff ,) j$P (1 REaulRED) s. x.4 . X '::. NI f; f %'s. -y s:.; > y.g.';; y '?i, .$s/ y 12 11 ?.\\ ' T.M% 10 'M2 4@ ' h -TEMPERATURE AND FLUENCE MONITOR ggg. {2. :;&. 12.421 mm (0.432 IN.) DI AMETER M2-

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't.<. 4 '5) 24.641 mm (0.97 IN.) LONG gl:.3.h: sp 'iy"':f??'y (4 REQUIRED) e g -.;j:y . +. - gik s,.....:. 21:. l'.5 w!:i, s,' g 4 8 M "$f'[; ' .k 7 - FUEL 800 6 12.433 mm (0.4895 IN.) Ol AMETER 43.28 mm (1.94 IN.) LONG 0 Q IRED) 5 h M3-4 NOTE: For stacks with one monitor, the monitor is located on top of the stack. 3 ..,dji- '%ES ses as F! 2 fils. L lM ' n s gc, <s:.. s F s' ?! .A +s ib(. b '* .5b 9;.'s ,, y .r M4 26 Qj ".. :.:. (..,.. n 'jj$ ;i@lWT .' UN..'N Fig. 4. Moni:or and fuel assem'oly for 4 monitor stacks. 21-

n TITLE: THERMAL DIFFUSIVITY OF H451 GRAP5iITE DOC. NO. 908923 AND TEMPERATURE MONITOR ANALYSIS IN ISSUE N/C FSV FUEL ELEIENT FTE-2 Graphite Tube (FIMA Monitor) sic Rod (Temperature Monitor) I c / - /f% % sN NN s s x4* N N N N g , ---. 4 en 6-i n..Q s s + s s s s's 12.42 mm , xs s

• s s-
• .~E (0.489" G RAPHIT,c 4

. q. CRUCISL: s, ,, s,, s,, s, A Lri'L_.. -s // AN s \\\\ \\ \\ Ns sNNNN' Nj p %., Niobium Tube I 24.64 mm t g (0.97") (Fluence Monitor) @ @, 4 - a A Graphite Crucible (Section A - A) 00SIMETRY WIRE / %- v m --:-- c 5 y-r / t FUEL PARTICLE HOLDER Nf 0810M TUBING ITEM MATERIAL 4 1. Temperature Monitor Sili' con Carbide Rod 2 2. Fertile FIMA Monitor ThC TRISO Particles 2 3. Thermal Neutron Vanadium Monitor 4. Thermal Neutron Vanadium - Cobalt Monia.or 5. Fissile FIMA Monitor UC TRISO Particles 2 7 t' l 6. Fast Neutron Monitor Vanadium - Iron 7. Fast Neutron Monitor Magnesium oxide - Nickel Oxide Fig. 5. Schematic diagram of monitors used in FSV fuel test elements. _- _ _ _ _ _ _ - ~. _ - _. _ _ _ - - _ - - - ~. - _ _. _

o i 4 N. I$$$ e < t2 tn l E N ** l P is # l ni h"' ;S lp LNy COOLED inSb l is @ @j INFRARED DETECTOR . M "' t; l l '] 3 - lQ 50 cm = 50 cm 1 a l[]o 50cmi COOLING HEAD ' CaF LENS FURNACE TUBE l L 2

c l

DS = g-h. i n, 40 p f (/ Es '\\ IRIS DIAPHRAGM \\ Hy ~ SiWINDOW g n SiWINDOW SAMPLE I DVM DVM IN PLACE J L J L l l TO DIGITIZING 4 OSClLLOSCOPE l c 10 GAIN UNITY GAIN EUFFER 5-10 x 10 GAIN h 5 2 PREAMP AND OFFSET AMP l n SELECTABLE SELECTABLE h* ~ BANDPASS BANDPASS l gg i z: l Mt Fig. 6. Schematic of infrared detector and associated optics far the high temperature thermal difIusivity apparatus.._

TITLE: THEPJW. DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908928 AND TEMPERATURE MONITOR ANALYSIS IN ISSUE N/C FSV FUEL ELEMENT FTE.2 100 80 o Q*sg't o o oo o o 2 o o o o i ,,, o o o y ~-- ? 2 'a-m 2 60 G m csz 8a<g 40 t H POCO AXF-SQ o EXPERIMENTALPOINTS

---

1983 GA MEASUREMENTS (AXF 50) 20

-.-.- 1983 GA MEASUREMENTS (AXM 50) (([ LITERATURE DATA (AXF 50 AND AXM 50) 1 I I i 0 200 300 400 500 600 700 l MEASUREMENT TEMPERATURE (OC) i i l Fig. 7. Thermal conductivity of unitradiated POCO AXF-SQ graphite. l 1983 CA measurements and literature data shown for comparison. 1, t

DOC. NO. 908923 ISSUE N/C FACE A O CORE No.11 O CORE No.13 40 A CORE No.15 A A ^ A a a a m g O 30 g a FACE B A 40 O ~ a E y 30 2 13 = FACE E 8, 40 b La d u a 30 FACE F 40 0 0 0 0 O 00 OA h O O o AA e AM g a AA 30 I I I I I 200 300 400 500 600 700 MEASUREMENT TEMPER ATURE (OC) Fig. 8. Tliermal conductivity of irradiated 11-451 graphite from FTE-2. DCC. NO. 908923 ISSUE N/C 50 O o O O O - -C v v _ 40 o V EE O O m n $ 30 u = 0 E E E 54 20

1. w O CORE 13,$ AMPLE 2, ASIRRA01ATED E CORE 13, SAMPLE 2, HEATED TO 7500C O CORE 13, SAMPLE 1, HEATED TO APPROX.8500C I

0 200 300 400 500 600 700 MEASUREMENT TEMPERATURE (OC) Fig. 9. Thermal conductivity of irradiated H-451 graphite frois face A of FIE-2 showing the ef fect of annealing to + 850 C.

TITLE: THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908923 AND TEMPERATURE MONITOR ANALYSIS IN ISSUE N/C FSV FUEL ELEMENT FTE.2 ^ ^ ^ \\ 0.0 W _ .M N 711

• C

-0.1 H131 M4 _M, a -0.24 w 710

• C E

O O 5 -0.1 H239 M4 5 e 5 a A A A -0.2 t h / s 658'C O H307 M1 O -0.1 O O REFEnt.NCED TO FIRST COOL DOWN CURVE A REFERENCED TO SECOND HEAT UP CURVE I I I I I I -0.2 300 400 500 60n 700 800 900 1000 TEMPERATURE (*C) Fig. 10. Plot of length change versus annealing temperature for monitors H131M4.11239M4, and H307M1. I 27

TITLE: THERMAL DIFFUSIVITY OF H451 GRAPHITE D0C. NO. 908928 AND TEMPERATURE MONITOR ANALYSIS IN FSV FUEL ELEMENT FTE-2 ISSUE N/C \\ 0.0 c..W%% - / o 640

• C e

H18 M1 -0.1 -0.2 f.6_ ,/ 672

• C

_3 H59 M3 0 -0.1 5x 0 v 5 0 -0.2 / N -^ A 655 *C H67 M1 O -0.1 O REFERENCED TO FIRST COOL DOWN CllRVE -0.2 A REFERENCED TO SECOND HEAT UP CURVE A 1 j l l l l l t 300 400 500' 600 700 800 900 1000 TEMPERATURE (

• C)

Fig. 11. Plot of length change versus annealing tetaperature for monitors H18M1, H59M3, and H67M1. i P c-e TITLE: THERMAL DIFFUSIVITY OF H451 GRAPHITE DOC. NO. 908923 AND TEf9ERATURE MONITOR ANALYSIS IN ISSUE N/C FSV FUEL ELEMENT FTE-2 60 40 O ra 7 6 w 75 g VO V 0 g 30 77 0 0 t

s E

G A DESIGN, H451 8 650,ADI ATION TEMPERATURE (IRR 20 p C FAST FLUENCE E 1.6 x 1021 N/cm ) 2 IEw 10 O FACE A O FACE B A FACE E 7 FACE F n . I I I I _I i 200 300 400 500 600 700 MEASUREMENT TEMPERATURE ('C) i Fig. 12. Thrmal conductivity of H-451 graphite from FTE-2 compared 2 with design curve for 1.6 x 10 n/cm (E20.18 Mev) at 650 C e.}}