ML20205E459
| ML20205E459 | |
| Person / Time | |
|---|---|
| Site: | 07109269, 07109032 |
| Issue date: | 03/30/1999 |
| From: | Roughan C AEA TECHNOLOGY |
| To: | Chappell C NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| NUDOCS 9904050187 | |
| Download: ML20205E459 (3) | |
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AFATECHNOLOGY AEA Technology
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QSAinc.
40 North Avenue Burhngton, MA ul803 Telephone PHI) 272-2tWK)
Telephone (8tm)) 815-1383 Facsimile G81) 27A2216 Mr. Ross Chappell Package Certification Section Spent Fuel Project Office US Nuclear Regulatory Commission 11555 Rockville Pike One White Flint Rockville, MD 20852 Fax:
301-415-8555 l
30 March 1999 i
Docket: 71-9269,71 9032
Dear Mr. Chappell:
We are making a required report under 10 CFR 71.95 and 10 CFR 21.21 concerning the model 650L and 650 Type B packages. As a result of experimental testing (30 foot drop only) we performed on the model 650L source changer we have determined that at low temperatures the carbon steel through bolts may not have the material toughness required to pass all of the required Type B(U) tests. A detailed summary of the experimental test results is attached. These tests were discussed with you during our meeting on March 9, 1999.
In summary,11 thirty foot drop test were performed using 5 different model 650L units. One unit when g
dropped from 30 feet and at a test temperature below -60F broke three of the four carbon steel through
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bolts. It has been approximated that the through bolts themselves were at a temperature below -70F. In addition to being well below required test temperature, the bolts may have experienced unusual conditions
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since they had seen more than eighteen years of service. Though these through bolts broke, the top plate remained in place and the sources remained secured in the shielded and locked position within the 650L.
Since this experimental test result indicates that there could be a patential problem with carbon steel
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through bolts at -40F, we wil.1 be upgrading the through bolts to s ainless steel as part of the re-testing and O
certification of the 650L. Upon the satisfactory completion of all the Type B(U) tests, we will upgrade all h
650Ls to stainless steel through bolts. In addition, any existing 650s in the field will be converted to 650L and will have stainless steel through bolts installed. Both the model 650 and 650L are AEA Technology property and are cycled through our facility on a routine basis. There are approximately 400 model 650L and 40 model 650 units in current use. We believe we can upgrade the existing units within six months after receiving approval of the test results.
Although we did not experience a failure of the 650L (i.e. the sources becoming unshielded) as a result of the bolts breaking in the one experimental test, it is possible that the top plate could have been moved out of position during a subsequent puncture and thermal test such that the sources could be exposed.
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We do not believe there is any significant increase in risk to the general public as a result of this finding.
This is based on the following:
-The ability for carbon steel to absorb impact energy is greatly reduced at -70F as compared to -40F.
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-The bolts had successfully passed other drops at low temperature in the same orientation.
in addition the bolts had successfully passed as a result of 30 foot drops in other orientations at both low and ambient temperature.
-Even with the failure of three of the four bolts there was no loss of confinement of the sources, which remained secured and locked in the shielded position.
-The 650 and 650L have been in use for mcre than 25 years (approximately 40,000 shipments) with no failure of these bolts. There have been numerous occasions of these packages falling off l
the back of moving trucks with no loss of structural or shielding integrity.
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-All of the 650 and 650L are owned by AEA Technology and as such are subjected to a routine quality control inspection prior to each shipment. This ensurca, that the packages are in good physical condition prior to transport.
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-The bolts only broke under the test temperature ofless than -70 C, this is an unlikely
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envirotunental condition to exist for the majority of shipments.
Based on all of the above, we believe there is no increased risk in continuing the transport of these devices.
Due to the results of these experimental tests however, we will be changing the bolts to stainless steel to remove any question about the ability of the package to meet all of the Type B(U) package requirements.
As stated earlier, we can perform this upgrade within six months of receiving approval.
If you would like any additional information please contact me.
Sincerely, j
i Cathleen Roughan Regulatory Affairs and Safety Manager Cc:
Salifu Dakubu, Commonwealth of Massachusetts i
Cc:
Document Control Desk, U.S. Nuclear Regulatory Commission l
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650L Experimental 30 Foot Drop Summary 4 Maich 1999 Test Unit Date /
Package Condition Orientation / Temperature 30 Foot Drop Results Time 650L-A 12Nov98 Normal 650L horizontal, short side Edges of top and bottom plates and lid S/N 170
/1015 CS Lid Bolts down (see Fig. 7) deformed W ' ht=82#
- CS Through Iwlts
- Warm,50 F 16Dec98 Modified 650L
- Top Corner bown (see Edge oflid deformed e
/1420 Lid Bolts replaced with Fig. 9)
Strain-Hardened Stainless Cold, <-40 C Steel bolts Package dropped once before j
650L-B 12Nov98 Normal 650L -
- Horizontal,long side Edges of top and bottom plates and lid e
S/N 156
/1105
- CS Lid Bolts down (see Fig. 3) deformed 4
Weight =8C;
- CS Through Bolts
- Cold, <-40 C 12Nov98 Package dropped once
- Horizontal, long side Edges of top and bottom pktes and lid
/1210 before down (opposite side) deformed Cold, <-40 C 12Nov98 Package dropped twice
- Vertical, upright Package hit bottom, bounced, rotated, e
/1220-before
- Cold, <-27*C and hit top One Lid Bolt broke I
e 12Nov98 Package dropped three times
- Top Corner Down Edge oflid deformed e
/1315 before:
Cold Remaining 3 Lid Bolts broke and lid
- One Lid Bolt broken on came off prior drop Damaged lock assemblies (lock assemblies struck impact surface after i
lid came off)
I 650L - C 19Nov98 Normal 650L Horizontal, short side
- Edges of top and bottom plates and lid S/N 2108
/1100 CS Lid Bolts down deformed Weight =78#
- CS Through Bolts Warm, 50*F 16Dec98 Modified 650L
- Vertical Upside Down Top plate bowed up -0.3" at center e
/1435 Lid Bolts replaced with (see Fig. 8)
Broke 3 of 4 Through Bolts Strain Hardened Stainless
- Cold, <-40 C Steel bolts Package dropped once before 650L - D 19Nov98 Normal 650L Vertical Upside Down Top plate bowed up ~0.3" at center a
S/N 1050
/1030
- CS Lid Bolts Warm,50 F Small yielding of 7hrough Bolts to Weight =85#
- CS Through Bolts acconunodate plate deformation 16Dec98 Modified 650L
- Top Edge of Lid Down Edge of lid deformed e
/1405
- Lid Bolts replaced with (CG not over impact Strain-Hardened Stainless point)
Steel bolts
- Cold, <-40 C Package dropped once before 650L - E 19Nov98 CS Through Boles
- Top Comer Down Edge oflid deformed e
S/N 107
/1000 Modified 650L
- Cold, <-40 C.
Top plate bowed up < 0.1" at center Weight =86#
Lid Bolts replaced with Broke 3 of 4 SS Lid Bolts Stainless Steel bolts Broke 3 of 4 Through Bolts
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