NCSC-106: Disposal and Examination of components from the Raleigh Research Reactor.
cylinder of the
arranged to send it to the
arrangements you have made for examination of the core and disposal of the
One of our staff members will accompany the shipment of reactor
in accordance with instructions and advice from
A separate letter will contain details of the shipping arrangements.
I list below the specific operations involved in handling the various
materials sent, and the data which seem to us should be obtained from
One or two containers will contain paper, gloves, kleenex
and other miscellaneous materials contaminated with traces of
fission product activity. The major portion of this can be disposed
of by incineration.
The principal shipping container for this material is the
2 1/2' x 3' x 5' aluminum safety envelope which enclosed the reactor
mechanism. The outside of this envelope is uncontaminated, but the
inside has adherent surface activity. The loosely adherent material
was removed, and most of the remainder could be removed by further
treatment. However, this envelope is to be replaced, and hence
this item may be scrapped and disposed of as the Laboratory may
Disassembled sections of the gas handling system were
placed at the center of 55 gallon drums which were then filled
with concrete. These containers are to be disposed of without
any attempt at recovery or examination.
It is estimated that as much as 20 grams of U235 may be
contained in the components and rinse-liquids included in this
shipment. The usual care and attention should be given to
retention, extraction and recovery of this uranium. Its location
The basic object of this examination is to determine why
failure occurred and to obtain any data which might assist in
the design of improved fuel containers.
Evidence clearly indicates the presence of at least two
separate defects which seemed to occur at approximately the
same time. (a) One is in one of the four cooling tubes. This
is a small leak. In pressure tests, 50 pounds of pressure on
water inside the sealed off coils showed a negligible drop in
several hours; 30" of Hg vacuum on the sealed off coils showed
a slow rise over a period of hours. It is suggested that the
four coils be removed intact from the sectioned cylinder for
testing and examination as to the location and cause of the
defect. At some point in the study, a look should be taken
at the inside surface of a cooling coil as well as the outside
surface. (b) The second leak is in the exterior wall of the
cylinder. At least a considerable amount of fuel solution
seems to have escaped into the annular space around the cylinder.
Heavy contamination was found on the shim-"rods", and some
clue to the depth of liquid in the annular space may be gained
by examination of the surfaces of these "rods". There is a
"butt" weld in the vertical wall of the cylinder, one inch from
the lower end where the shaped bottom and the wall of the cylinder
were joined. The lid was welded on at the top. Fifteen tubes
connect to or project through the top surface of the cylinder.
All are welded in place.
It is not know, of course, where the leak in the cylinder
is or why it occurred. There are the welded points which may
have been defective, a defect in the metal components is by
no means impossible, there was a tendency of the fuel to
precipitate as uranium peroxide which may have caused unexpected
corrosive attack; finally, there was on record one fairly large
pressure surge and one or two smaller ones over the preceding
months due to erratic operation of the catalyst in the gas
If corrosive attack is found to be the cause of the defect,
any clues to the reason for this attack should be sought.
One small sample of the fuel solution removed from the
reactor core and placed in storage is included in this shipment.
It is anticipated that a careful analysis of this for anomalous
components, metallic ions, evidence of UO4 precipitate, etc.
may give some clue to the corrosive action which may have
occurred inside the fuel cylinder.
This analysis has particular importance for it may indicate
whether or not the fuel solution should be reprocessed before
it is placed again in the reactor.