ML20042A019

Comments in Response to 810818 Ltr Re RIS0 Tests 022 & 013

ML20042A019
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	10/07/1981
From:	Knudson P RISO NATIONAL LABORATORY
To:	Voglewede J Office of Nuclear Reactor Regulation
Shared Package
ML20042A017	List: ML20042A019 ML20042A024
References
21-PK-GC, NUDOCS 8203220563
Download: ML20042A019 (5)

Text

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il RisoNationalLaboratory Y Postbox 49 DK-4000 Roskilde, Denmark

- - Phone (03)371212, Telex 43116 Cable address: Risatom Dr. John C Voglewede Date 1981-10-07 Reactor Fueis Section, CPB-DSI re .

21/PK/GC Office of Nuclear Reactor Regulation Dept. Metallurgy U.S. Nuclear Regulatory Commission Washington, D.C. 20555 USA -

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Re. Risc Tests 022 and 013

Dear John,

Thank you for the copy of your letter of 18 August, arriving here a few days ago (we have still not seen the original). Our comments are as follows:

(a) First I must correct an error in my telex of 15 April:

The density increase for the 013 pellets should read-1.1% (not 0.9%).

(b) The requested details of our resintering testing are provided

./. in the enclosed note, B-513, by our Hans Carlsen. Briefly, although the 022 and 013 are of different origin, the available data do not give support to an assumption that the densification of the 013 pdlleth should be double that of the 022 pellets. " -

(c) When comparing code predictions of the fission gas release in the two tests, it should be borne in mind that the O22 test was irradiated at fairly high power levels, whereas the 013 pins were ramped after a long base-irradiation at decreasing power. If this. difference in power history would 8203220563 820222 cont. -

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give different fission gas releases, then the prediction with a given code could also be different for the two tests, depending on the basis of fission gas release model in the code.

Best regards, -

Per Knudsen i .

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METALLURGY DEPA,RTMENT October 1981 Report-B-513 HC/GC Hans Carlsen RESINTERING OG PELLETS FOR RISO TESTS O22 AND 013

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PELLET FABRICATION

"I" Two different powders were used for these pellets:

022: 2.28% enriched powder was delivered by UKAEA, Springfields; the lot for Ris was presumably taken from a larger batch.

013: 1.45% enriched powder was made in the Risc laboratorie,s for a small number of test fuel pins.

The 022 and 013 pellets were made in two different campaigns at Risc.

RESINTERING TEST

./. The attached table shows the results from the resintering testing of archive pellets from the 022 and 013 campaigns.

The resintering was done in H at 1700 C for 24. hrs. The density 2

was measured by the buoyancy method in water.,

022: 3' pellets with H/D = 1 and 3 pellets with H/D = 1.5 were examined, each pellet being measured 3 times. The ATD% for-s the two pellet lengths were judged similar,' and their averag'es were combined yielding ATD% = 1.1 0.1% (10 on single measurement). -

013: 2 pellets were examined, each pellet being measured 3 times.

T'he average results is then 1.1 10.6 (10 on single measurement).

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COMPARISON REGARDING RESINTERING j The O22 and 013 pellets are known to be different in these respects:

(a) Enrichment (b) Source and batch size of powder (c) Pellet fabrication campaign

. (d) As-sintered density _ , , , , , ,, _ , ,, _ _

(e) Spread on density increase in resintering.

Item (a) would not per sc cause any difference in pellet proper-ties, whereas item (b) might well. Regarding item (c), it is noted that slightly different sintering temperatures were.used (O22: 1675 C, 013: 1700 C) . The attached table shows only a minor difference in as-sintered density, item. (d) . The average density increase in resintering is the same for the 022 and 013 pellets, but the spread is larger for 013. It should be noted that only two 013 pellets were available for resintering testing.

In summing up, the measurements do not give support to an assump-tion that the densification in resintering of the 013 pellets should be considerably larger than the O22 pellets.

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Pellet Pre-resintering II/D Ib.

Post-resintering

%TD %TD Standard %E %TD Standard A%TD Avg. deviation Avg. deviation A%E 1 s ,

94.78 95.97 1 94 . 74 94.74 0.04 96.05 96.01 0.04 1.27

94. T 96.00 94.71 95.68 .:

1 2 94.74 94.75 0.05 95.68 95.67 0.01 0.92 1.10 +0. P ,

94.80 95.66 i 94.78 95.92  !

3 94.80 94.80 0.03 95.96 95.92 0.04 1.12 Test: IIP O22 94.83 95.88 '

Fab.: 70 94.44 95.46 * *

' ION: M371 94.41 94.46 0.06 95.59 1

95.54 0.07 1.08 94.52 95.97 -

94.64 95.74 1.5 2 94.63 94.65 0.03 95.83 95.80 0.06 1.15 1.15 0.08 94.68 95.84 94.63 95.84 3 -94 .61 94.63 0.03 95.88 95.86 0.02 1.23

_ 94.66 45 A9 93.IG 95.14 A 94.36 94.46 0.10 95.12 95.14 0.03 0.68 1.1 0.6 Test: IIP 013 94.55 45 17 Fab.: 69/67 I 94.31 95.98

' ION: M198 B 94.32 9 4 .'66 95.96 95.94 0.08 0.06 1.58 94 . 45 95.87 All quoted standard d,ediations refer to single measurements, not the average value

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