U.P.R. control rod latch

MISSING IMAGE

Material Information

Title:
U.P.R. control rod latch
Physical Description:
12 p. : ill. ; 27 cm.
Language:
English
Creator:
Hedgecock, J. L
U.S. Atomic Energy Commission
North American Aviation
Publisher:
North American Aviation, Inc.
Place of Publication:
Downey, CA
Publication Date:

Subjects

Subjects / Keywords:
Electromagnetic devices   ( lcsh )
Nuclear reactors -- Control   ( lcsh )
Genre:
federal government publication   ( marcgt )
non-fiction   ( marcgt )

Notes

Statement of Responsibility:
by J.L. Hedgecock.
General Note:
Cover title.
General Note:
"Subject category, Physics"
General Note:
"NAA-SR-Memo-685."
General Note:
"Work performed under contract no. AT-11-1-GEN-8."--P. 2
General Note:
"Date declassified: April 14, 1955"--P. 2

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 005254686
oclc - 702207981
System ID:
AA00012264:00001


This item is only available as the following downloads:


Full Text
...A- )iA'^ 6.- 5


UNITED STATES ATOMIC ENERGY COMMISSION


NAA-SR-Memo-685


U.P.R. CONTROL ROD LATCH


By
J. L. Hedgecock








April 29, 1953


North American Aviation, Inc.
Downey, California


- i~~'~A-'~'


Technical Information Service, Oak Ridge, Tennessee


















Subject Category, PHYSICS.


Work performed under Contract No. AT-ll-1-GEN-8.

Date Declassified: April 14, 1955.


This report has been reproduced directly from the best
available copy.

Reproduction of this information is encouraged by the
United States Atonic Energy Conmission. Arrangements for
your republication of this document in whole or in part
should be made with the author and the organization he
represents.

Issuance of this document does not constitute authority
for declassification of classified material of the same or
similar content and title by the same authors.


AEC, Oak Ridge, Tenn.


The Atomic Energy Commission makes no representation or warranty
as to the accuracy or usefulness of the information or statements contained
in this report, or that the use of any Information, apparatus, method or
process disclosed In this report may not Infringe privately-owned rights.
The Commission assumes no liability with respect to the use of, or for
damages resulting from the use of, any Information, apparatus, method or
process disclosed In this report.












U.P.R. CONTROL ROD LATCH


By

J. 0. Hedgecock




Several configurations have been considered for the latch on
the control and safety rod drive units.
The four basic types are shown in sketches on Pages 4, 6, 8,
and 10, and their performance curves are given on Pages 5, 7, 9, and 11,
respectively. Type A was the first considered; it proved to be rela-
tively inefficient because friction was not used to best advantage. Type
B gave considerable improvement and Type C gave a slight further improve-
ment. In Type D the holding links are no longer actuated by toggle links,
but by a wedge or cone. In the performance curves, the latch holding load
is the load that must be applied upward to the latch mechanism to hold the
latch holding links in the spread position shown in the sketches. The
negative loads shown indicate that the latch is self-locking because of
friction and give the force that must be applied downward to release the
latch. The total load that must be held by the electromagnet which controls
the release of the latch will be called the total holding load and will
exceed the latch holding load by the weight of the latch actuating rod.
The weight of the latch actuating rod may tentatively, in the absence
of a final design, be estimated at 10 pounds.
For a given and constant coefficient of friction, the latch may be
designed so that the latch holding load is as small as desired.
However, the coefficient of friction may not be known with much precision
and may change with time because of pitting, wear, etc. We may expect
the friction angle, 9, to be approximately 100 (coefficient of friction
f = tan 0 = .176) for chromium plated bearing surfaces, but we wish the
electromagnet to hold even if the friction angle should be as low as 5
(f = .087) and we wish the latch to release even if the friction angle
should be or become as great as 200 (f = .364). We may tabulate the
following information taken from the performance curves of types C and
D, Types A and B being chiefly of historical interest at present:


Type C Type D

Toggle or wedge angle, p or y 81o 24
Latch holding load at Q = 5 56 Ibs. 108 Ibs.
Latch holding load atO = 200 10 Ibs. 10 Ibs.
Total holding load ate = 5 66 ibs. 118 Ibs.
Total holding load at = 200 20 Ibs. 20 ibs.









Thus we see that the electromagnet for Type D should have nearly twice
the holding power as that required for Type C.
A way to reduce the size and response time of the holding
electromagnets is to adjust the toggle angle The holding power of
the electromagnet can be initially calibrated as a function of the
current passing through it. Then at each shutdown, the minimum current
necessary to hold the control rod load can be determined and the toggle
angle 3 adjusted as necessary to compensate for changes in the coef-
ficient of friction and insure safe release. Type D cannot be adjusted
in a similar manner.
Type C also offers a means of forcibly retracting the holding
links should there be a tendency for them to stick out and impede re-
moval of the control drive rod through the lower shielding.
Type D permits the use of three or more holding links, while
Type C is limited to two unless ball and socket joints are used. This
consideration is felt to be of minor importance though, since the
stresses are not excessive in any case.
All in all, I believe that Type C is to be preferred for three of
the four points mentioned above;
1) Smaller electromagnet required
2) Adjustable after installation
3) Holding links can be forcibly retracted.












CONTROL ROD
LOAD 750#


LATCH
ACTUATING
ROD


U.P.R. CONTROL ROD LATCH TYPE A.












220


200 8 = FRICTION ANGLE -

480 -

460 -
8=50
440 -

420 -

8 400 400
z

o 80

o 60 -8=450
4J


0 =20
I 20 -
20

-J

-20 -

-40 -

-60 -
NEGATIVE LOADS ARE FRICTIONAL
LOADS THAT MUST BE OVERCOME
TO RELEASE THE LATCH; THE
LATCH IS SELF-LOCKING.
-400 -

-420
800 820 84 86 880 900
8, TOGGLE ANGLE, DEGREES


U.P.R. CONTROL ROD LATCH PERFORMANCE OF TYPE A.










CONTROL ROD
LOAD-750#


LATCH
ACTUATING
ROD


U.P.R. CONTROL ROD LATCH TYPE B.


GOO



















120 -

400 -

80 -

60

40

20
-

0

-20

-40 -

-60 -

-80 -

-400
800


U.P.R. CONTROL ROD LATCH PERFORMANCE OF TYPE B.


82 84 86 88
R, TOGGLE ANGLE, DEGREES


90










CONTROL ROD
LOAD -750#


LATCH
ACTUATING
ROD


U.P.R. CONTROL ROD IATCH TYPE C.





















0=o0 = FRICTION ANGLE

B- =8=5



8= 15O





NEGATIVE LOADS ARE FRICTIONAL
- LOADS THAT MUST BE OVERCOME
TO RELEASE THE LATCH; THE
- LATCH IS SELF-LOCKING.


I I I I


400

80

60

40

20

0

-20

-40

-60

-80

-100
7


840 860
ANGLE, DEGREES


U.P.R. CONTROL ROD TOGGLE TYPE C.


82
P, TOGGLE


s8


800


90










CONTROL ROD
LEAD-750#


LATCH
ACTUATING
ROD


U.P.R. CONTROL ROD LATCH TYPE D.


*















300 -

280 -

260 -

240 -

220 -

200 -

480 -

460 -

440 -

420

400 -

80

60

40-

20 -

0 -
480


U.P.R. CONTROL ROD LATCH TYPE D.


24 260
y, WEDGE ANGLE, DEGREES





























































































4




UNIVERSITY OF FLORIDA
1 2 III01 I I ll II 0905
3 1262 08917 0905




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