An electrical lead has insulators imbedded in an inner conductor rod to form an annulus between the rod and a surrounding outer sheath. This annular space is filled with gas which conducts heat and prevents electrical leakage

Breitwieser, R.

Kaufman, W. B.

English

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REPLY TO
ATTN OF. GP
L
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
WASHINGTON. D C 20546
JUL 1 2 1974
TO: KSI/Scientific & Technical Information Division
Attn: Miss Winnie M. Morgan
FROM: GP/Office of Assistant General
Counsel for Patent Matters
SUBJECT: Announcement of NASA-Owned U.S. patents in STAR
In accordance with the procedures agreed upon by Code GP
and Code KSI, the attached NASA-owned U.S. Patent is being
forwarded for abstracting and announcement in NASA STAR.
The following information is provided:
U.S. Patent No. : ?.
Government or
Corporate Employee
Supplementary Corporate
Source (if applicable)
NASA Patent Case No.
-s. A
NOTE - If this patent covers an invention made by a corporate
employee of a NASA Contractor, the following is applicable:
YES /—7 NO
Pursuant to Section 305(a) of the National Aeronautics and
Space Act, the name of the Administrator of NASA appears on
the first page of the patent; however, the name of the actual
inventor (author) appears at the heading of column No. 1 of
the Specification, following the words "...with respect to
an invention of ..."
/ >
"\ ( I !•:•"•/•>, -.
r J V- N..''xV -<-'/-
Bonnie L. Woerner
Enclosure
https://ntrs.nasa.gov/search.jsp?R=19740019570 2020-03-17T15:02:37+00:00Z
Uftited States Patent
Kaufman et al.
[ i i ] 3,821,462
[45] June 28, 1974
[54] HIGH CURRENT ELECTRICAL LEAD
[75] Inventors: Warner B. Kaufman, Broadview
Heights; Roland Breitwieser,
Fairview Park, both of Ohio
[73] Assignee: VEB Filmfabrik Wolfen, Wolfen,
Germany
[22] Filed. July 19, 1972
[21] Appl. No.: 273,222
[52] U.S. CI 174/15 C, 174/28, 174/111,
310/4 R
[51] Int.Cl H01b9/04
[58] Field of Search 310/3 R, 4 R; 322/2 R;
174/19,20,28,77 R, 111, 15 R, 15 C
[56] References Cited
UNITED STATES PATENTS
2,282,004 5/1942 Scott et al '174/20
2,754,349 7/1956 Werner 174/28
2,958,721 11/1960 Fiet et al 174/20 X
3,493,792 2/1970 Untermyer .. . 310/4
3,542,938 11/1970 Graneau 174/28
3,585,271 6/1971 R e y n o l d s . . . . 174/15 C
Primary Examiner—J. D. Miller
Assistant Examiner—Harry E. Moose, Jr.
Attorney, Agent, or Firm—N. T. Musial; G. E. Shook;
J. R. Manning
[57] ABSTRACT
An electrical lead has insulators imbedded in an inner
conductor rod to form an annulus between the rod
and a surrounding outer sheath. This annular space is
filled with gas which conducts heat and prevents elec-
trical leakage.
6 Claims, 1 Drawing Figure
12
PATENTEDJUH28H74 3.821,462
16
THERMIONIC
CONVERTOR — 12
- n
 3,821,462
1 2
HIGH CURRENT ELECTRICAL LEAD trical lead assembly 10. This assembly 10 is used to
conduct current from a thermionic converter 12 which
ORIGIN OF THE INVENTION • is capable °f Producing a verv h"8h current.UK1U1N Uh i Ht IIN v tiN l IUIN -
 thermionic converter 12 is mounted in a nuclear
The invention described herein was made by employ- 5 reactor and operates in a high gamma flux area 14
ees of the United States Government and may be man- which may be near the reactor core. This high gamma
ufactured and used by or for the Government for gov- flux area 14 is surrounded by an inner wall 16 forming
ernmental purposes without the payment of any royali- a housing in the reactor. An outer wall 18 is spaced
ties thereon or therefor. from the inner wall 16 to form a container that is filled
BACKGROUND OF THE INVENTION •'« with water 20 for shielding and cooling.
The electrical lead assembly 10 is utilized to conduct
This invention is concerned with an improved electri- high electrical currents from the thermionic converter
cal lead for use in a high gamma flux. The lead is partic- n through the water filled container. The lead assem-
ularly useful with thermionic converters in nuclear re- bly 10 has a sheath 22 that that is mounted in the outer
actors
-
 15
 wall 18 and extends toward the inner wall 16. The
Thermionic converters operate in high gamma flux
 sheath 22 comprises a stainless steel tube. By way of ex-
locations of nuclear reactors. Current is removed from
 ample> a stainless steel tube of 0.250 inch outside diam-
such thermionic converters through electrical leads.
 eter and 0 014 inch wall thickness with a length of 60
Conditions imposed upon the conductors in these
 inches has been satisfactory for the sheath 22 in a typi-
leads are more severe than those for conductors of 20
 caj in^n^ion
other test devices operating in a nuclear environment. ^
 eiectricaily conducting rod 24 extends axially
Conductors used in nuclear tests applications have through the sheath 22 and passes through a suitable ap-
been insulated with swaged magnesia or alumina
 erture in the outer wal, 18 Aluminum is preferred for
housed in stainless steel tubes.
 the rod 24 because of its low susceptibility to nuclear
Electrical leakage at high current levels .-, probable 25
 radiation heatj However, it is contemplated that a
with swaged leads due to impurities in the swaged ma-
 rod be uged jn certain applications. By way
tenal. Heat flux into the conductor from the hot test
 of e ^ an aluminum rod 0. 1 87 inch in diameter by
piece results in a large expansion of the long conductor.
 62 inches , was inserted } ^ aforementioned
The swaged lead expands mostly at the hot end thus ,m-
 stainless sted ^ Such a rod was satisfact for jts
posing a force on delicate components of the device JU • . .
 d
under test. Spaced insulators 26 engage the rod 24 and conduct
SUMMARY OF THE INVENTION the inner surface of the sheath 22. These insulators 26
These problems have been solved by an electrical maintain the rod 24 out of contact with the sheath. In-
lead constructed in accordance with the invention. In- 35 sulators 26m the form of sapphire balls have been sat-
sulating sapphire balls imbedded at spaced distances 1S?C'°ry' ™e af°™tlO"*d alumm""1 rod waf Pr°-
along an inner conductor rod form a gas annulus be- ™d*d T'^ ]^66 ?'°62 «nch diameter holes wh.ch were
tween the rod and a surrounding outer sheath of stain- dnlled 0^45 inch deep and 1 20 apart at one inch in-
less steel tubing. The hot end of the rod is fixed in a cer- terva\s- SaPPb.ire balls °! °-062 'nchudlf mele/ we™ m-
met insulator. The annular space between the rod and 40 serted Wlth a hiht Press fit.in,to these holes- The/od was
the tube is filled with an inert gas which conducts heat then mserted into the stainless steel tube to form the
to the stainless steel tube and surrounding water while 'ead assembly 10.
preventing electrical leakage. ^n e'ectnca' conductor 28 which extends from the
thermionic converter 12 is rigidly secured to the end of
OBJECTS OF THE INVENTION 45 the rod 24 adjacent the inner wall 16. An insulator 30
It is, therefore, an object of the present invention to surrounds the connected ends of the conductor 24 and
provide a coaxial conductor in which electrical current 28- T"6 insulator 30 forms a rigid support for these two
leakage is minimized. conductors. A cermet material has been satisfactory for
Another object of the invention is to provide an im- the insulator 30.
proved electrical lead for use in a high gamma flux lo- 50 A bracket 32 rigidly mounts the insulator 30 in the
cation in a nuclear reactor. 'nner wa" 16. The bracket 32 further rigidly mounts
Another object of the invention is to provide an im- the end of the sheath 22 onto the inner wall 16.
proved coaxial conductor which utilizes insulating balls As seen in the drawing the ends of the sheath 22 and
imbedded in the conductor to form a gas annulus. rigid conductor 24 adjacent the inner wall 16 are both
These and other objects of the invention will be ap- rigidly supported. The conductor 24 is free to expand
parent from the drawing and specification which follow axially along the sheath 22 away from the insulator 30.
wherein like numerals are used throughout to identify Thus there is no load placed on the cermet insulator 30.
like parts.
The annulus between the rod 24 and the sheath 22 is
DESCRIPTION OF THE DRAWING &0
 first evacuated and then filled to about 60 millimeters
The drawing is a cross-sectional view of an improved of mercury inert gas pressure. Helium or argon is satis-
coaxial lead constructed in accordance with the pres- factory for this purpose. Heat transmitted along the
ent invention. conductor rod 24 from the thermionic converter 12 is
~-~ *i dissipated through this gas and the sheath tube 22 to aDESCRIPTION OF THE PREFERRED 65 ^ ^
 NQ ^ ^ ^^ ,eakage .g encountered
EMBODIMENT because the annulus is first evacuated and then filled
Referring now to the drawing there is shown an elec- with inert gas of high purity.
3,821,462
While the preferred embodiment of the invention has
been known and described it will be appreciated that
various structural modifications may be made without
departing from the spirit of the invention or the scope
of the subjoined claims. By way of exanple, it is con-
templated that lead assembly 10 may be used as a coax-
ial conductor.
What is claimed is:
1. An electrical lead for conducting a high current
from a thermionic converter operating in a high gamma
flux area in a nuclear reactor that is enclosed in a water
filled container comprising
a tubular sheath extending through said container
whereby the water therein cools the same,
an electrically conducting rod extending axially
10
15
through said sheath, the outer surface of said rod
being spaced from the inner surface of said sheath
to form an annulus,
a low molecular weight inert gas of high purity se-
lected from the group consisting of helium and 20
argon under a pressure of about 60 millimeters of
mercury contained in said annulus to conduct heat
from said rod to said water cooled sheath and pre-
vent electrical current leakage,
25
a plurality of spaced insulators in said annulus for
maintaining said rod out of engagement with said
sheath, and
a rigid insulator mounted on the end of said sheath
and said rod adjacent to said nuclear reactor, said
rod being free to expand axially within said sheath
along said spaced insulators away from said rigid
insulator and said nuclear reactor.
2. An electrical lead as claimed in claim 1 wherein
the electrically conducting rod is of a material selected
from the group consisting of aluminum and copper.
3. An electrical lead as claimed in claim 1 wherein
the spaced insulators comprise solid spheres of an insu-
lating material.
4. An electrical lead as claimed in claim 3 wherein
the solid spheres comprise sapphire balls, said rod
being provided with a plurality of spaced recesses for
receiving said balls.
'5. An electrical lead as claimed in claim 1 wherein
the sheath comprises a stainless steel tube.
6. An electrical lead as claimed in claim 1 wherein
the rigid insulator comprises a cermet material
30
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45
50
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60
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High current electrical lead

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