ML19343A759
| ML19343A759 | |
| Person / Time | |
|---|---|
| Site: | 07109015 |
| Issue date: | 10/31/1980 |
| From: | TRANSNUCLEAR, INC. |
| To: | |
| Shared Package | |
| ML19343A758 | List: |
| References | |
| 17770, E-2362, NUDOCS 8011210181 | |
| Download: ML19343A759 (8) | |
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E-2362 Revision 0 TN-8 AND TN-9 SAFETY ANALYSIS REPORT O
ADDENDUM FOR TI!E TN-8L PACKAGING Octobar 31, 1980 l
17NO 801 1210 lT/ 5 ONE NORTH BROADWAY, WHIT E PL AINS, NEW YORK 10601 TE LEPHON E : 914 761-4060 C ABL E : TRANSNUC WHP TELEX: 13 1498
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TABLE OF CONTENTS l.
l Page
1.0 INTRODUCTION
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2.0 DESIGN MODIFICATION 1
f 3.0 PACKAGE CONTENTS 2
3 4.0 EVALUATIONS 4.1 Thermal Evaluation 3
4.2 Shield Evaluation 6
5.0 REFERENCES
8 Drawing No. 9317.138, Revision A; TN-8L Packaging (located in pocket at rear of folder).
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1.0 INTRODUCTION
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The purpose of this addendum to the TN-8 and TN-9 Safety Analysis Report (Ref. 1) is to describe and justify a design modification to reduce the weight of the model TN-8 packaging (Ref. 2). The weight reduction is realized by reducing the number of rows of fins from 150 to 104 rows.
The removal of 46 rows leads to a larger spacing between the remaining rows of fins and impacts the shielding effectiveness and heat rejection capability.
The TN-8 packagings with 104 rows of fins will be designated by the unique model iden-tification TN-8L.
It will be identical to the TN-8 model in all other respects.
3 Therefore, no changes in fabrication, inspection, or testing methods will be required.
2.0 DESIGN MODIFICATIION The fins for the TN-8 packaging are described in the SAR (Ref. 1), Chapter II, Section 2.1.
The SAR Concept Drawing No. 9317.01, Rev. J notes that there are 150 plates (rows) with approximately 152 fins per plate around the outer shell. This Icads to a total of approximately 22,800 fins.
For the TN-8L, the fin description is still valid except that the number of rows is reduced by 46 rows from 150 to 104 rows as shown on Drawing No. 9317.138.
This reduces the number of fins to approximately 15,800.
There are no other changes to the TN-8 design.
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i The elimination of 46 rows of fins reduces the weight of 1
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the TN-8 by approximately 1000 kg.
The structural evaluation of the TN-8 concluded that all applicable criteria are satisfied with a design packaging weight with contents of 35,680 kg.
This conclusion remains valid for a TN-8L pack-aging having a slightly lower weight.
The elimination of 46 rows of fins reduces the heat rejection capability of the TN-8L to 2/3 that of the TN-8.
As shown in.3.0 below, the TN-8L can transport 3 fuel assemblies each with a residual power of 7.9 kw or less.
The elimination of 46 rows of fins also reduces the gamma j
shielding. It is shown in 4.2 below that radiation dose ratec for the TN-8L are lower than'for the TN-8.because the reduction in source strength of the fuel assemblies to be transported in the TN-8L is greater than the reduction in shielding effectiveness due to the elimination of the fins.
3.0 PACKAGE CONTENTS The physical charac.teristics of the fuel assemblies which may be transported'in the TN-8L are the same as those described j
for the TN-8 in the SAR (Ref. 1), Chapter-I, Section 2.
Three (3) fuel assemblies can be transported in the TN-8L, if their residual power does not exceed 7.9 kw per assembly.
The results of calculations for residual power of one assembly are tabulated in Section 4, Chapter I of Reference 1, for a cooling period of'150 days after discharge from the reactor.
By extending the cooling period to 225 days, the power per assembly is reduced to 7.9 kw as shown in the following
-comparable tabulation.
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1 (k- )
Irradiation T= Irradiation t= cooling Po= Power P/Po P
w Cycle Time (days) time (days) Generated During Cycle
(. W)
M I'
330.
940' 14.2 0.40x10-4 0.6 3
II 330 585-17.75 0.75x10-4 1.3 III 330 225 21.3 2.8x10-4 6.0 7.9kw I+II4III 990 Total Residual Power, P,
=
Thus, the package contents for the TN-8L may be "P" or "P1" assemblies with residual power as follows:
Number of Maximum Total Assemblies Residual Power Maximum Residual Per Assembly, kw Power, kw 3
7.9 23.7 C-Fuel assemblies with irradiation histories which are different from tnose used in calculating the maximum residual powers may also be transported in the TN-8L provided that the residual powers do not exceed the foregoing values.
4.0 EVALUATIONS f
l 4.1 THERMAL EVALUATION-4.1.1 Normal Conditions of Transport The heat dissipation characteristics of the TN-8 and TN-9
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packagings under normal conditions of transport were based upon the results of a full scale cross section model. test, as reported in the SAR (Ref. 1), Annex A to Chapter IV.
.The cylindrical cross section of the model approximated that of the TN-8 and TN-9.
3 w
w m
The model differed in that it had 116 rows of fins, while
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the TN-8 and TN-9 have 150 and 124 rows of fins, respectively.
Based upon the results of the model test, empirical formulas were developed to calculate the temperature gradients through the packagings.
The temperatures calculated by the empirical formulas for packaging components for both the TN-8 and TN-9 are reported in Chapter IV of the SAR.
The temperatures predicted by the formulas have been confirmed during thermal acceptance tests for five TN-8 and TN-9 packagings.
The maximum decay heat load is 23.7 kw for the TN-8L (Section 3.0).
Calculations have been performed to estab-lish the number of fin rows required to reject this and the solar heat load without exceeding TN-8 temperatures (Table 3.3.8, Chapter IV of the SAR) for the regulatory normal condition of transport, i.e. sunlight at an ambient temperature of 130F in still air.
The method of calculation is the
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same as that used in Section 3, Chapter IV.
Intermediate and final results are as follows:
Solar heat load, Ps = 2.9 kw Total Heat load P'
= Ps + P uel = 2.9 + 23.7 = 26.6 kw (22,870 Kcal/hr) f By retaining the same value for power per fin, p'= 1.45 Kcal/hr, the fin temperatures for the TN-8L will be the same as those for the TN-8.
The required number of fins is then 15,770.
With 152 fins per row, as for the TN-8, 104 rows of fins are required for the TN-8L.
The foregoing assumes that the difference in number of fin rows, 116 for the test model and 104 for the TN-8L, has a
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negligible effect on heat transfer characteristics.
One
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would expect slightly better performance and lower temperatures for the lesser number of fins.
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The principal mode of heat transfer through the packaging components is by conduction.
Since temperature differences are directly proportional to the heat flow by conduction, the temperature difference between the inner compartments and outer shell of the TN-8L is only 2/3 that of the TN-8.
This results in substantially lower internal temperatures for the TN-8L.
Maximum fuel temperatures are further reduced because of the smaller temperature difference between fuel and compartment walls due to the lower decay heat.
As required by the SAR (Ref. 1), Chapter VIII, Paragraph 1.4.5, each TN-8L will be subjected to a thermal acceptrnce test to verify its heat dissipation characteristics prior to first use.
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(_)s 4.1.2 Accident Conditions The response of the TN-8 and TN-9 packagings to the regulatory thermal accident cpnditions were based on temperature measurements made on a complete half scale cask model and a full scale slice model during and after fires.
The tests and calculations are described in the SAR (Ref. 1), Chapter V, Section 3 and Annexes C and D of Chapter V.
The fins provide the principal path for heat transfer from a fire into the packaging.
The solid resin shielding acts as a thermal insulation during the fire.
Since the TN-8L has a lesser number of fins, the total heat flow into the packaging will be less and all internal temperatures will be lower than those predicted for the TN-8.
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4.2.
SHIELD EVALUATION 4.2.1 Normal Conditions of Transport The shielding effectiveness of the TN-8 packaging was determined by_ calculations as reported in the SAR (Ref. 1) in Annex A to Chapter III, Section 1.2.
The-maximum dose rate at 2 meters calculated for the TN-8 packaging trans-porting three PWR. assemblies cooled 150 days was 9.9 mR/h.
This dose rate is calculated for-the face of the TN-8 pack-aging sheltering two assemblies and is the limiting dose rate in the design of the TN-8.
These calculations have been repeated with the revised values of number of fins and cooling _ period for the TN-8L, as described in the following.
1 As stated in Section 2.0, the only. change to the shield I
design for the'TN-8L is a reduction in the number of rows
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of fins from 150 to 104.
This results in a reduction in the effective thickness (uniform thickness around the central portion of the packaging) of the-fins from 25.7mm to 17.8mm.
1 As before, the 104 rows will be equally spaced around the circumference.
For the' gamma dose rate calculations, the removal of G.8 cm 1
of effective copper _ thickness reduces the value of b for the shield au follows -(b =J[syiXi, for the various -shielding materials and their respective thicknesses):
2 Group III photons Group IV' photons i
TN-8 shield:
b-=
13.6 11.95 TN-8L shield:
b=
13.25 11.66 Offsetting this reduction in shield effectiveness is the decrease in the linear source strength (SL) for gamma photons
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resulting-from the increase.in the-cooling period from 150 to 225 days.
For one PWR assembly cooled 150 days, the linear source strength, in photons /sec.cm, from Ref. 1 is:
Group III photons Group IV photons r
SL =
2.98 x'1011 1.55 x 1011 From the TN-8L calculations, SL after 225 days of cooling is:
Group III' photons
, Group'IV photons t
SL =
1.65 x 1011-9.99 x 1010 i
For the neutron and capture gamma dose rate calculations, the neutron source strength of.3 PWR assemblies cooled 150
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days was utilized in the TN-8L dose rate calculations. This is a conservative assumption as the neutron sources decay as cooling period increases, although less than the gamma sources.
l The total dose rate calculations at 2 meters from the side of the TN-8L packaging sheltering two assemblies were re-performed incorporating the reductions in effective copper i
fin thickness and source strengths.
The results of the calculation yielded a~ maximum total' dose rate of 8.6 mR/h f
at 2 m for the TN-8L which corresponds to the 9.9 mR/h calculated for the TN-8.
As expected, the reduction in gamma photon source strength more than compensates for the 4
decrease'in effective copper thickness.
The dose rates i'
from other quadrants of the TN-8L packaging will similarly i
be lower than-the. corresponding values calculated for the
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b j -O As required by the SAR (Ref. 1), Annex M to Chapter VIII, a shielding efficiency verification shall be performed after
'first loading of each TN-8L packaging to confirm the calculated dose rates.
i 4.2.2 Accident Conditions of Transport i
After.fie regulatory tests, the dose rates at 1 m from the packaging must be less than 1000 mR/h.
The value of the total' dose rate calculated for the TN-8 after loss of the t
resin shielding resulting from the regulatory fire was 210 mR/h.
The dose rate for.the TN-8L wil)'not. exceed this value due to the lower gamma photon and neutron source strengths of assemblies cooled 225 days versus 150 days.
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5.0 REFERENCES
1.
Transnuclear,.Inc. TN-8 and TN-9 Safety Analysis Report, Revision No.
8, dated April 8, 1980.
2.
USNRC Certificate of Compliance No. 9015, Revision No.
2, dated June 18, 1980.
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