ML19274E629
| ML19274E629 | |
| Person / Time | |
|---|---|
| Site: | 07109506 |
| Issue date: | 03/02/1979 |
| From: | Roeder J ENERGY, DEPT. OF |
| To: | Macdonald C NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| NUDOCS 7904090372 | |
| Download: ML19274E629 (5) | |
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Department of Energy Albuquerque Operations Office P.O. Box 5400 r
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Albuquerque, New Mexico 87115 l '.l..'i ~ isig
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Charles E. MacDonald, Division of Fuel Cycle and kbs '
Material Safety /NRC Nf SHIPPING CONTAINER MODEL NO. MS 27684-2 18, 1978, requesting additional Reference your memo of December information on subject container (also identified as 9506).
Attached are copics of our response to the comments in referenced memo, also by copy of this memo, Mound Facility is requested to 760065 pre tide dire::tly to you copies of MRC drawings No. AYC aau AYC 760064.
Your efforts in the review of this container are greatly appreciated.
ack R. Roeder, Director 3perational Safety Division Won:ELB
Enclosure:
As stated, 2/12/79 II. N Hill, Area Manager, DAO, w/o encl.
cc:
T. L. Dunckel, ECT/HQ, w/ encl.
73040s0 779,
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February 12, 1979 NRC Connents On 9506 Packace Letter, Hill r.o Mullins/ Cave 1/?2/70 The following information is offered in response to the letter referenced above concerning NRC con 1ents on Mound container 9506.
NRC Corrents on 9506 DRAWINGS Provide liensanto Research Corporation Drawina Mos. AYC 760065 and AYC 760064 for the inner container body and cover.
These drawings should identify all signifi-cant safety features, e.g., dimensions.. materials of construction, welds and seals.
MRC Response: tiound can provide two copies each of the referenced drawinas.
The prinary purpose of these drawinos is to provide instructions for the fabrication of the cocoonents shown thereon.
Therefore, many of the specific safety features are not noted on the drawir.as, but are re#errsi to in the SARP.
Held snecifications are contained in an eight page document Drawing No. 1-14841 and are also included in the SARP.
NRC Comment CONTAINMDIT Show that the containment carabilities of the packagina following normal con-ditions of transport and accident danace conditions are sufficient for paciacing containino plutoniun oxide powder. Reculatory Guide 7.4 may be used to develoo an accentable test to denenstrate adecuate containnent. Also, the aoplication should address how the requirerents of 10 CFR s71.42 will be net.
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- February 12, 1979 FRC Resconse: Paragraphs 5.2 and 5.3 of the SARP describe how radioactive 7
material, includino powders, are contained inside the steel inner container which passed both the normal and hypothetical accident con-ditions without daraqe. Tne cansules in which special form naterial is sealed are routinely leak tested and wiped. The "0" ring sealed metal cans in which normal form oxide powder centainers are placed, are always wiped prior to being placed into 9506 inner containers.
All wines must show 20 dnm or less (essentially " cold") before they are accepted for packacir.q for shictent.
In addition, the limit of an accentable leak rate for an MRC containment used prior to first use is several orders of naanitude better than the Regulatory Guide 7.4 minimum requirerent. The wide spectrun of containers used inside the contain-ment vessel preclude their individual submittal for ancreval. Althouah these inner containment vessels do contain the material durino packacino operations and may contain the material throuahout the shicoino sequence, the primary con-tainment vessel remains the unit which was sut;nitted to and successfully passed the hypothetical accident test sequence.
The SARP provides the details of the hypothetical accident conditions and shows that there was no damage to the containment vessel during the test sequence.
NRC Co. ment, 4
TESTING AND fiAINTENANCE Discuss the maintenance procram to be used to ensure the nackagn containment capability under continued m e.
This should include init.iai, ocriocic and pre-a shipment tests.
The minteence schedule should include the inspection, test and replacenent schedule for cemnonents that comorise the containment system.
Regulatory Guide 7.4 my be used for containment tests before first use and for periodic testing.
For assembly verification testing, it is recontended that a test of sufficient sensitivity to detect c release of no core than a Type A quantity of material in 10 days be used.
ing is used for asseably When leak tesg/sec and the rainimum verification the mxinum sensitivity is 1 x 10-3 atm-cas sensitivity is 1 x 10-1 ata-cm3 sec (air at 25 C and 1 atm leaking to a 1 x 10-2
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atmambient).
MRC Resoonse: The present raintenance crearam employed at tiound recuires that immediately prior to each packacino oceration, the followino operations be conducted on the containment vessel of the 9506 shipping containers.
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- 1. Identify the radioactivc
- terial form.
- 2. Assure that the container delivered to the packaging coordinator does not leai by taking a v:1pe prior to insertion into the inner container (must be 20 dpm or less, i.e. essentially cold).
- 3. Examine the threads, "0" ring, "0" ring groove and lid seal areas for the presence of scratches, dents and foreign matter.
- 4. Lubricate the threads and gasket.
- 5. Examine the container delivered to the packaging co-ordinator for presence of the proper serial number, the absence of dents, scratches and foreign cetter.
- 6. Pack this container inside the 9506 inner container with metal packing material such as steel wool, cooper triminas, nickel spheres etc., as prescribed by the Quality Control Engineer.
- 7. Seal the 9506 inner container.
- 8. Wipe inner container (must be below 20 dpm).
In addition to these inspections, the outer comoonents of the 9506 shipping container such as the centerinq material, bo't threads and closure rino are verified to be in good condition and free from contaminatio-E pe ier.ce at ilound has verified that these precautions have been adequate to prever.'. the use of inferior containers and the release of radioactive material during shipments.
The vendor is required to certify the Helium leak test results on each new container and t'RC verifies these results through receiving inspection operations at Iound. The leak test is verified to several orders of magnitude cetter than required by Regulatory Guide 7.4.
In additien, if durin;. any inspection con-ducted prior to use, the inspector observes a condition.ihich is unusual or ~
which may cause him to question whether a seal can be obtained, he submits the container to the lion-destructive Test Group for another leak test.
NRC Coment CRITICALITY In order for any package to qualify as Fissile Class I it is necessary to demon-strate that the requirements of 10 CFR 571.33 are met.
In iractice, Fissile Class I indicates that controls for criticality in transcort are not required.
This is possible since there is essentially no neutron interaction between packages under normal conditions of transport and at least 250 damaged packages
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, February 12, 1979 are subcritical.
It should be recoanized that Fissile Class I packaqes could be comingled ylth other Fissile packanes.
In the case of the subject package it has not been shown that any number (infinite array) of packages are sub-critical for the normal conditions of transport.
In this reaard, we need a description of the criticality nodel and analysis and resu!*.s which support a Fissile Class I designation. Also, it should be noted tha: 'ne Transport Index for Fissile Class II should be rounded up to the first dect al place in accord-ance with 10 CFR 071.39(2)(b).
MRC Response: While it is true that the criticality analyses for the subject packaqes did rot consider an infinite array, in the real world an array consisting of 2500 packages is commonly accepted within the criticality safety cemmunity as beine the equivalent of an infinite arrey.
In fact, Hugh Paxton, a recognized criticality expert at LASL, has stated that if an array of as few as 250 packages is da:onstrated to be subcritical, then an infinite array will also ce subcritical. (Criticality Centrol in Operations with Fissile Material,
- 11. C. Paxton, LA-3366 (Rev) 1972). One is hard-pressed to imaqine an actual ship-ment array even beginning to approach 2500.
In addition, criticality evaluations are traditionally heavily saturated with conservatism and worst possible case scenarios.
flote is taken of the fact that the Transport Index for Fissile Class II should be rounded up to the first decimal place. That is exactly what has been done in Table II of tbc SARP which specifies the Transport Indices for various loading conditions of the J506 container.
Mound Facility would like to invite an fiRC representative to visit Mound so that basic concepts and design criteria may be reviewed and discussed freely. Obser-vations of i:ound's containers and test facilities alona with discusions of Mound's Quality Progran should provide a nuch better mutual understanding of the overall requirunents for a safe packace for the containment of radioactive caterial durina shipment. Moreover such a neeting would pave the way for a more expedient evalu-ation and acceptance of future shipping containers which may be developed at Mound.
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