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Патент USA US3096273

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July 2, 1963
Filed June 14, 1957
;______ ..J)
. Attorneys
Patented July 2, 1963
in the bearing sleeve 22. The broaching cutter 8 is
carried on the part 24 of the impact pin 7 and rests against
a step 26 between the two parts 24 and 25. The part 25
Graham Eades Lindsay, London, and Sidney John J0_slin
Waldron, Harwell, England, assignors to United Klug
dom Atomic Energy Authority, London, England
Filed June 14, 1957, Ser. No. 665,812
Claims priority, application Great Britain June 14, 1956
3 (Ilaims. (Cl. 204-1932)
This invention relates to arresting devices for falling
of the impact pin 7 projects from the bearing sleeve 22.
A stop in the form of a washer 27 and a nut 28 is carried
on the end 29 of the impact pin 7 where it projects from
the adaptor 19.
The operation of the device will now be described with
reference to the case of a control rod falling into a vertical
10 control rod channel of a nuclear reactor from an initial
In a nuclear reactor having vertically suspended control
or shut off rods, the possibility of the failure of the means
supporting the control rods with consequent damage when
the control rods fall has to be considered.
It is an object of the present invention to- provide means 15
to arrest a falling body in one or more stages depending
on the circumstances of the fall so that large impact forces
are avoided.
According to the invention, a device for arresting a
position in which the control rod is suspended with its
lower end passing through a hole in a charge pan situated
on the top of the core of the reactor. At the start of the
fall the conditions shown in the drawings apply.
The control rod 1 falls until the conical face v15 of the
cup 3 hits a complementary face 31 formed around the
edge of the hole in the charge pan through which the
control rod 1 is falling. The cup 3 is thus arrested by the
charge pan and the kinetic energy of the falling control
falling body comprises in combination with the body an 20 rod 1 is absorbed as the compression spring 2 is com
pressed between the cup 3 and the ring 4 carried by the
impacting member, a vertically resilient means coupling
support head 6. The load which is set up in the com
the impacting member and the body yieldable linking
pression spring 2 is taken by the shear pins 5 which
means such as a coupling releasable when the load in the
couple the ring 4 with the support head 6. If this load
vertically resilient means exceeds a predetermined amount
to allow the body to continue its fall free of the impacting 25 now exceeds an amount determined by the shear strength
of the shear pins 5 they fail and the control rod 1 and
member and energy dissipating means for ?nally arresting
the body.
An arresting device in accordance with the invention
will now be described with reference to the accompanying
drawings. In the drawings:
associated support head 6 fall away from the cup 3, com
pression spring 2 and ring 4. The control rod 1 then
continues to fall freely until the downwardly projecting
impact pin 7 of the broach strikes an impact stool 32
situated at the foot of the control rod channel. The im—
pact pin 7 is arrested by the impact stool 32 and due to
the impact the broaching cutter 8 is forced along the
the device.
liner 9.
Referring to the drawings there is shown a control rod
The liner 9 is cut as the broaching cutter 8 is forced
1 which has associated with it an arresting device compris
along it and as the kinetic energy of the falling control
ing two principal parts, ?rst at the top of the control rod 1
rod 1 is dissipated in the broaching operation the control
(FIG. 1), a spring 2 which acts between ‘an arrester cup
rod 1 is ?nally decelerated to rest.
3 and a ring 4 secured to the control rod 1 via shear pins
FIG. 1 is an elevation of one part of the device.
FIG. 2 is an elevation in section of the other part of
It will be seen that if the control rod 1 falls from a
5 and a control rod support head 6 of cylindrical form. 40
position such that the cup 3 receives only a moderate
Second (FIG. 2) at the bottom of the control rod a
broaching arrester mechanism comprising an impact pin
impact on being ‘arrested by the charge pan the shock of
the fall will be absorbed in the compression spring 2
7 carrying a broaching cutter 8 movable in a free cutting
without fracture of the shear pins 5 and the control rod 1
stainless steel liner 9 held within a body tube 10' mounted
on the control rod 1.
45 will be arrested at this point with no damage. However,
if the impact is more serious, damage is con?ned to the
Referring to FIG. 1 in more detail the control rod 1 is
shear pins 5 and the liner 9 which can easily be replaced.
attached to the support head 6 by a shank 11 formed
The liner 9 is provided with internal grooves 30 to ensure
integral with the support head 6. The shank 11 is
that the cuttings produced are in the form of chippings
screwed in a threaded hole 12 in the upper end of the
control rod \1. The support head 6 has ‘an integral lifting 50 which will not cause jamming of the breach.
We claim:
eye ‘13 and a conical ?ange 14 divides the support head 6
1. A body adapted to be suspended vertically and to
from the shank 11. The arrester cup 3 has a conical
extend through an aperture in a ?xed structure having an
impacting face 15 formed round its base. A hole 16 in
upper complementary face and a lower impact stool, a
the base of the cup 3 and an ‘aperture 17 de?ned by a
ring 18 welded to the upper end of the cup 3 allow it to 55 support head ?xed to the upper end of said body, an
arrester cup having an inner vertical bore through which
slide on the support head 6 against the loading of the
said support head extends, said arrester cup having a face
spring 2.
on its outer surface adapted to engage with said comple
Considering FIG. 2 in more detail the body tube 10
mentary face for arresting the fall of said arrester cup,
of the broaching arrcster mechanism has an end adaptor
19 which is screwed into the lower end of the control 60 vertically resilient means ?xed inside said arrester cup,
yieldable linking means connecting said support head to
rod 1. The free cutting stainless steel liner 9 is held within
said resilient means and adapted to yield ‘and release said
the body tube 10 between an internal end face 20 of the
support head and body to fall free of the cup and resilient
adaptor 19 and an internal end face 21 of a bearing sleeve
means when the force across said linking means increases
22 which is screwed into the lower end of the body 10‘.
The liner 9 has internal grooves 30. The broaching cutter 65 to a predetermined magnitude, and energy absorbing
means at the lower end of said body adapted to engage
8 is ring shaped and has six equally spaced external cut
with said lower impact stool to absorb the energy of the
ting edges. The cutter 8 is held within the liner 9 and its
free fall of said support head and body.
end 23 adjacent to the bearing sleeve and is ?tted into
2. The apparatus claimed in claim 1 wherein said means
the liner 9 by prebroaching the liner 9 fora short distance
from the end 23. The broaching cutter 8 is carried by 70 at the lower end of said body for absorbing the energy of
free fall comprises an impact pin, a broaching cutter
the impact pin 7 which has two parts, i.e., an upper part
24 bearing in the adaptor 19 and a lower part 25 bearing
carried by the impact pin and held within a free cutting
tubular liner attached at the lower end of said body, said
pin, breaching cutter, and tubular liner being disposed so
that upon impact the pin drives the breaching cutter into
the tubular liner whereby the energy of the impact is dis
sipated by the cutter cutting into said tubular liner.
3. The apparatus claimed in claim 2 wherein said
tubular liner is adapted with grooves extending on the
surface to be cut at an angle to the line of cutting.
References Cited in the ?le of this patent
Kuller ________________ __ Oct. 24, 1911
Pegard _______________ __ Oct. 28, 1952
Butler ________________ __ Oct. 26, 1957
Reynolds _____________ __ May 26, 1953
Greenhalgh et al _______ __ Mar. 10, 1959
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