ML20236S233
| ML20236S233 | |
| Person / Time | |
|---|---|
| Site: | 07103044 |
| Issue date: | 07/14/1998 |
| From: | Ebert M EDLOW INTERNATIONAL CO. |
| To: | Chappell R, Elliott C, Messick C ENERGY, DEPT. OF, NRC |
| References | |
| NUDOCS 9807240214 | |
| Download: ML20236S233 (7) | |
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Edlow International Company 1666 Connecticut Ave., N.W., Suite 201 Washing on. D.C. 20009 U.S.A.
f[fo2 FACSIMILE MESSAGE 0
e-mail:lnfo@culow.com DATE:
July 14,1998 TO:
Carol Elliott, DOE-SR FAXNO:
(803) 725-8573 Chuck Messick, DOF SR (803)557-3996 l
Richard Boyle, DOT (202)366-3753 Ross Chappell,NRC (301) 415-8555 FROM:
Marty Ebert PAGE(S)$
7 fax:(202) 483-4835
SUBJECT:
Brazilian Fuel For your information, attached is the GNS report " Containment of Radioactive Material in GNS-11 or GNS-16 During the Transport of Damaged IPEN MTR Fuel Assemblies with High Burnup", which I received this morning by fax.
Regards f
Marty Ebert i J l
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9807240214 980714 PDR ADOCK 07103044 C
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__ Origirial'BUrlE i
Technische Notc*
GN.S.
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er BEP 98-5017 I
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Hr. Eick, GNS-BEP Von:
Hr. Dr. Kohl, WTI-JB k
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t Zeichen: Dr.K/gV86000098 MD Kople:
Mr. Dreesen, GNS-BEP Telefon: (02461) 933-150 j
Hr. Deine, GNS-BEP Fax:
(02461) 933-400 Mr. H0ggenberg, GNB-EBA Datum:
09.07.98 j
Dec700M. OAK ENS 11. oNS 18, Felsstrung. D.le4M-RE, PEN l
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Containment of radioactive materialin GNS 11 or GNS 16 during transport of damaged IPEN MTH fuel assemblies with high burnup t
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The transport casks GNS 11 and GNS 16 shall be loaded with irradiated fuel I
assemblies from IPEN Sao Paulo, Brazil. Part of these assemblies have been found defect by visualinspection. Corrosion of the fuel plate aluminum cladding has been observed, and release of oxidized dust particles from the active fuel zone uncovered by this corrosion into the cask cavities cannot be excluded.
i in this note the source term from such radioactivity release is estimated, and the pbssible leakage of this material from the casks is determined. It is estimated, how many defect assemblies can maximally be loaded into the casks so that for normal l
transport conditions there is no release in excess of 10 Aa/ hour.
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Cask inventory of defect assemblies with high burnup
@om the 127 MTR fuel assemblies B4 have an activity inventory of more than 4 TBq, ahd for 41 of these there is more than 10 TBq per asser.nbly, the maximum value is 160 TBq. Only 25 of these assemblies are considered to be undegraded, l. e. without l
defects.
I The bumup of these 84 assemblies lies between 11 and 72 mwd / ass, and the coot,ng time since discharge from the reactoris between 0.7 a and 33 a.
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i F6el with low (LEU) and high (HEU) enrichment is ivithin these 84 assemblies.
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, Technische Natia SEP 98 5017_ -- - -.
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F/A radioactive nuclide inventory, As To estimate the radionuclides inventory of these p/A's, bumup calculations for three t
F/A groups have been performed. The computer code ORIGEN-2.1 with the bumup cross-section library PWRUS was used for simplicity reason.
l (a) LEU fuel with 25 mwd / ass and 28 a cooling' time (b) HEU fuel with 69 mwd / ass and 0.9 a cooling time (c) LEU fuel with 68 mwd / ass and 1.6 a cooling tima 1
1 For these cases the As of the fuel has been calculated on the basis of IAEA Safety i
$eries No. 6, Table 1. The results are t
i (a) Aa = 4.54E10 (b) A = 1.29E11 1
(c)
An~= 8.19E10 l
i These An values can be understood when one considers, that the relative contribu-tion of fission products (which have a large Aa) decreases ~ with increasing decay q
time, and that LEU fuel will produce much more plutonium than HEU so that a lower i
As must be expected for these assemblies.
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According to IAEA Safety Series No. 6 the maximum permissible release rates are (for the nomenclature here and in section 5 cf. ANSI N14.5 (1987)):
Ij 10*AA1our i
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4 Aa/ week i
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With the Arva!ues given above
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(a) N 12.6 Bq/s
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(b) %
35.8 Bq/c
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.(c) %
22.8 Bq/s
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T9chntche Notiz BEP 96 5017
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Permissible leakage rate Ln and aerosol activity l
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The design leakage rate for both casks is 1E-4 std om2/s (10 h Pa t/s) for air.
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From the maximum intamal pressure pun in the cask i
f Puu = 127 kPa (GNS 11)
Puu = 273 kPa (GNS 16) the maximum permissible leakage rate Lu is calculated-1 i
Lu = 1E-4 (Pow -100 kPa)/(100 kPa - 1 kPa)
Lu
= 2.73E-S emls (GNS 11) j a
j Lu
= 1,75E-4 cm*/s (GNS 16) i i
[ Remark For the IPEN fuel the heat load will be less than 10 % of the cask design i
Value of about 1.5 kW. Therefore P Wll be smaller than assumed here, adding UN some conservatism to this analysis.]
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From these the maximum permissib!e activity concentration Cu in the casks is derived: Cu = Rw/l.a.
The maximum permissible activity which may be in the cask cavities in form of an i
aerosol is given by multiplication with the cask's free. volumes, which le approxi-mately 2.2E5 cm* for each cask. Tim result is GNS 11 GNS18 i;
Fuel (a) 1.02E11 Bq '
1.58E10 Bq Fuel (b) 2.89E11 Bq 4.50510 Bq Fuel (c) 1.84E11 Ba 2.87E10 Bq l
Table 1: Maximum aerosol actMty ir the casks limited by the permissible releaso rates for normal conditions 1
i If'these activity is present in the casks in form of an aerosol, the regulatory limit for i
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Ru will bo reached.
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Technische Notit BEP 96 5017 i
Page4 i
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Permissible F/A defects l
In the following it is assumed (on the basis of discussions with NRC and Edlow), that j
for the defect F/A's 1 % of the cladding surface' has corroded away, so that 1 % of
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the active fuel meat is exposed to oxidation. As it.is not,known how far this oxidation has progressed into the meat, a release fraction is assumed.
!I As only the product of defect and release fraction: enter into the following calculation, j-other proportions can easily be derived from the results given below.
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Fuel (a) is representative for about 37 fuel assemblies with activities of 4 T8q...
Li 10 TBq.1 % of the activity then amounts to 4E10..1E11 Bq of aerosol released from such assemblies in the case of defects of the extent assumed here.
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From Table 1 one finds that 1 -2 such assemblies would exhaust the containment
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potential of GNS 11, while GNS 16 could accept less t'an half of such an assembly.
i Fuel
' f assum(b) represents 'about 40 fuel assemblies with activities of 3 TBq..190 ed leaked activities of 3E10 Bq..1.9E12 Sq per. assembly. Only assemblies j-. with a release of less than 2.8gE11 Bq fit into GN' 11 (cf. Table 1), which is true for i
S approximately 12 of the assemblies belonging to this group, wMle only 2 assemblies j
,i are below the more restrictive activity limit for GNS 16.
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Fuel (c) represents 7 assemblies with activities of 68 TBq.. 115 TBq, none of which
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Conclusion
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it has been shown'that for cask loadings with. defect IPEN F/A's in GNS 16 or GNS 11 the possible release of radioactive materialis limiting for the amount of fuel assemblies which can safely be transported without violating the regulatory limit for I
< - ev assembli;s which can saf:ly be transport 5d with ut violating tha ragulttory limit for f ' cetivity r:lers3 und;r norm I transp:rt conditions. VGry few of tha highly irradiited a
c;semblios cf IPEN can be 10 dad into GNS 16, assuming a r:l::se fraction cf 1 %
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of the activity inventory per assembly due to cladding degradation, and generally not I
more than 1 -2 such assemblics per loading are permissible, in the case of GNS 11 restrictions are somewhat less, and 1 - 2 defer:t LEU and several HEU with relative f
low activity can be loaded into the cank 9hout violation of the limit on activity i
release.
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- .> j Technische Nota BEP 98~5017 l
Pages e
t f Still it is not possible to find a full cask loading r
j one includes the 25 nondegraded IPEN assemblies into.one. loading. To a more detailed anatysis would be required. For such an analysis it would b d
t)ve to have a much preciser description of the adent of the full cladding the aerosol release fraction due to these dedocts.:Only on the basis of such l
pper bounds for possible acthdty release and j
ion it will be possible to erve sa e u di f
f (to optimite cask loading in this respect. If su individually to remove some conservatism inherent to the approach chosen i
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TOTAL P.07
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