ML20058D107

Requests for one-time Ltr Amend for Certificate of Compliance 9168 for Model 8-120B

ML20058D107
Person / Time
Site:	07109168
Issue date:	11/02/1990
From:	Paquin P CHEM-NUCLEAR SYSTEMS, INC.
To:	Osgood N NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
References
611-0646-90, 611-646-90, NUDOCS 9011050331
Download: ML20058D107 (6)

Text

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_3ICHEM-NUCLEAR SYSTEMS,INC.

220 Stoneridge Drive

• Columbia. South Carolina 29210 November 2, 1990 611-0646-90 Ms. Nancy Osgood Division of Safeguards and Transportation, NMSS-U.S. Nuclear Regulatory commission 11555 Rockville Pike Rockville, MD-20852 j

SUBJECT:

REQUEST FOR ONE-TIME LETTER AMENDMENT FOR MODEL NO. CNS 8-120B, CERTIFICATE OF COMPLIANCE No. 9168 Chem-Nuclear Systems, Inc. (CNSI) respectfully requests approval for a one-time letter amendment to the 8-120B Certificate of compliance.

This amendment is proposed to allow transport of three SDS vessels and their associated cask liners from the TMI plant to the.Barnwell disposal facility in the 8-120B.

An amend-ment is necessary because each of the three liners exceeds the certificate of Compliance limit on contents of 2000 x A, having 2

activities of 3685, 3366, and 2220 times A2, respectively.

3

'The three liners are fabricated with 10" thick, 148.lb/ft con-crete that is poured between concentric 1/4" thick steel plates.

The source activity will be encapsulated in the SDS vessels, which will in turn be placed inside the liners (one per liner).

Concrete will be poured into the liners and around the SDS vessel

.until.the liner is completely filled, forming a monolithic struc-ture containing the. radioactive materials.

The. liner will then be:placed inside the cask along with sufficient shoring to hold

'the liner in place.

.All three liners will be transported to the Barnwell disposal facility.

Transport will begin shortly after approval of the h

amendment, and will be completed befora December 31, 1990.

TMI L

has requested that these liners be transported and disposed of before that date.

CNSI.has evaluated alternatives to transporting the liners in the i

L 18-120B.

The only alternative we find feasible is to transport the SDS vessels (without. liners) in a CNS 1-13G cask, transfer them to.the 8-120B liners once at Barnwell, and then dispose of the liners.

This alternative is unattractive because transfer.

ring the vessels from the 1-13G to the liners would result in a large, otherwise. unnecessary dose to the personnel involved.

Also,-shipping the vessels to Barnwell in the monolithic, con-crete structure provided.by the 8-120B liners is. intuitively more p

. appealing.

L In evaluating the merit.of this proposed' amendment, two issues should be addressed.

The first is containment.

Calculations in show that for transporting with a source term of n1n 9011050331 901102

{DR ADOCK0710gGi (803) 256-0450

• Telex: 216947 j

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Ms. N. Osgood Page Two e

3685.-x A2 in containment (using the worst-case liner), the cask Leontainmengmustgetestedtoamaximumpermissibleleakrate-of 1.04'x 10' ata-cm /sec of air.

.Concerning the containment issue, it should also be noted that the calculations for the maximum permissible leak rate are overly

-conservative because they assume the source-term concentration is generated by 1% water in the cavity, which all vaporizes.

In fact', for this application there will be no water in containment to vaporize-because of the monolithic, concrete structure of the liner.

Thus the potential for vapor leakage is precluded.

The second issue we have. addressed for this application is the structural adequacy of the cask.

We have reviewed the 8-120B SAR and even though two of the liners exceed the minimum Category I classification (greater than 3000 x A ) for packages, we have 2

concluded that the structure provides a sufficient margin of safety for transporting the TMI-liners.

Our reasons for conclud-ing'this are:

O The strong, monolithic structure created by the concrete and steel' liner would mitigate the consequences of an accident even in the unlikely event of containment rupture of the cask.

L 0

Draft RegGuide DG-7001 defines Category I as greater than 3000 x A2, or greater than 30,000 Curies.

Therefore, one would expect'a Category-I package to contain contents with

.these. orders of. magnitude of radioactivity, such as in spent Lfuel or reprocessing waste packages.

However, there.are only two liners.that exceed 3000 x A2 in radioactivity, and L

these two are marginal and contain only 1780 and 1544 Curies respectively.

D..Even though the contents exceed the maximum Category II quantity, the package is still within the design margins of l

safety for ductile-fracture-under Normal and Hypothetical Accident Conditions.

-All other potential issues have been addressed, including ther-1 mal, criticality,-shielding, and operational procedures.

We have

' concluded that these will not be impacted by transporting the TMI L

liners.

D l

Jus I stated earlier, the three liners must be transported to

-Barnwell and disposed of before December 31st.

This will require three separate round trips between TMI and Barnwell, so we must

4 -

Ms. N. Osgood Page Three

begin-as soon as possible.

Therefore, your assistance in ex-c pediting a resolution to this question of the amendment will be-greatly appreciated.

We are hoping to begin. preparation for the first shipment no later than November 14th, so we would like to know before that date whether or not the 8-120B can be used.

Thank you for your assistance with this matter.

Please feel free to call me if you have any questions.

Sincerely, I

Pa'; rick L. Paquin Manager of Engineering Attachment-t t

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.L ATTACHMENT 1 REQUEST FOR LETTER AMENDMENT FOR 8-120B CONTAINMENT CALCUIATIONS The isotopic' distribution of the three liners in question is l

shown on page_3 of this attachment.

Referring-to the 8-102B SAR, Section 4, the calcular sn for the

-acceptance test leak rate makes the following assumptions:

1 0

The maximum containment activity = 2000 x A.

2 D

There is a maximum of 1% of water in containment, and it all vaporizes.

D Ie, the maximum permissible leakage rate for normal conditions of transport, is limiting.

Based on these assumptions and the accompanying calculations it is determined in Section 4 of the SAR that 1g.2000, the maximum permissible leakage rate at test conditions with a 2000 x A 2 source term in the cavity, is 2.09x10'8 atm-cm /sec of air, and 8

that the required sensitivity is 1.04x10'8 ata-cm /sec.

8

,Now, it will be=shown that performing the testing at a leak rate.

of 1. 04x10-e 8

atm-cm /sec meets the requirements for testing with 1

2 source-strength in the cavity.

From Section 4:

3685 x A i

Ry.2ee, 2.7 8x10-18 Aa

• • • • ~

C.noco 6. 66 x10-8 Aa L

n ll Using the calculations on pg.

4-6, with 3684 x A, thon:-

2 C.3g,5 - 3 6. 85 A* - 1. 23x10-4 A y

3 3 X10, -

i L

'}

f Therefore, 2 '. 7 8x10 -1* Aa I L -3ses "

y 1.23x10-' Aa And:

i L.sses, 6. 66 x10-5 u

- 0.54 L

Lu.aeo'o 1.23x10-4 I

4-i 1 of 3

J.;

4 E

For. conservatism',

say-4.~n3

0. 5-x 4 200o.

And since 4 is

=

proportional to 4, then 4 3 3

0. 5 4 200o.

=

b sees = 0. 5_ x 4,2eco

= _0. 5 x (2. 09 x 10)/sec

= l.04 x 10 ata-cm

- Therefore the leak rate at which the cask will be tested for trans-porting the three TMI liners is 1.04 x 10 atm-cm /sec.

For this 8

- test, the sensitivity will be i x 1.04 x 10

= 5.2 x 10 atm-3 cm /sec.

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