1. Attached is copy number 32 of the 15 February 1963 Report of the
Foreign Weapons Evaluation Group, also referred to as the Bethe Panel
Report. Initial instructions on the handling of this type of report were
issued by the White House in National Security Action Memorandum No.
193, dated 3 October 1962. This memorandum is attached and should remain
an integral part of the Bethe Panel Report. Attached also is a copy of
Memorandum for All Holders of the Foreign Weapons Evaluation Group
Report of 14 and 15 February, dated 8 March 1963.
2. The sensitivity of the data contained herein is emphasized. Previous
instructions pertaining to the handling of Bethe Panel Reports apply.
Accordingly, it is requested that a record be maintained of all persons
having access to the report, or the information therein, and that access
be on a strict need-to-know basis.
Attachment
February 15,
1963
REPORT OF THE FOREIGN WEAPONS EVALUATION GROUP MEETING
OF 14 & 15 FEBRUARY 1963
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I. INTRODUCTION
The present report is supplementary to that of 7 December on the
USSR test series of 1962, and
it has not yet been possible to give specific consideration to all
the events of that series.
From 18 December to 25 December 1962 the Soviets conducted 11
additional experiments at their Novaya Zemlya site. On two occasions
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pairs
of shots were conducted within a half-hour of each other. On the
last day (25 December) two tests were conducted only 6 minutes
apart, and on 23 December there were three in a half-hour period.
The first two of these were only two minutes apart, and although
some fresh debris was collected, it was impossible to separate the
debris or the acoustic signals from these near simultaneous events
so that of these, it is merely known that the total yield was
probably not more than a few tens of KT. In addition, several of the tests of this late
December group were less than 100 KT; that is to say, in the low yield group that the Soviets
have usually conducted near their site at Semipalatinsk. One of the
December tests, JOE 178, would appear to have been a dud; at least
the yield was rather small and there is [text not
declassified]. Some of the other small yield shots may be
of this nature but they have not been examined as yet.
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Altogether, the late series added 5 tests less than 100 KT, 2 between 100 and 1000 KT, 2 between 1 and 2 MT, 1 about 6 MT, and 1 at 26 MT. The
totals for the 1962 series from August to December are consequently:
66 tests of which 35 were less than 100 KT, 11 between 100 and 1000 KT, 14 between 1000 and 10,000 KT, and 6 larger than 10,000 KT. (This may be compared with the Soviet series of
1961 which consisted of 44 tests, with 24 small yields, 6
thermonuclears between 100 and 1000 KT, 12 between 1000 and 10,000, and 2 larger than
10,000 KT.)
The report of 7 December was concerned only with the Soviet tests
above a megaton. The present report is mainly concerned with the
devices of intermediate yield (100 to ~1000 KT), although reference is made to the two larger
devices of the December series. It has not yet been possible to
complete the analysis of the large group (35 tests) of lower yield
devices.
The devices considered here are, consequently, [text not declassified] suitable therefore for tactical or
short-range applications or possibly for use with light missiles or
conceivably multiple warheads. As discussed in earlier reports,
nothing can be said on the basis of evidence available as to the
specific nature of the applications the Soviets may have in mind for
these devices. It may be noted that in 1962 the Soviets considerably
increased their attention to devices in this intermediate range,
although they have not yet given it the concentrated attention that
we have directed to this class of device.
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The report is divided into several sections: II. on the devices
between 500 and 1200 KT, III. on
those around 200 KT, IV. on the
large yields fired in December, and V. on the general topic of
developments
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in the basis of analysis of the performance of Soviet
thermonuclear devices.
II. YIELDS FROM 400 TO
1200 KT
In this yield range considerable progress was observed. There was
some progress in thermonuclear technology, and the Soviets tested
[text not declassified].
[Facsimile Page 6]
[text not declassified]
[Facsimile Page 7]
[text
not declassified]
III. TESTS AROUND 200
KT
In the fall 1962 series four Soviet nuclear explosions were detected
that had measured yields in the neighborhood of 200 KT. These were JOEs 139, 167, 176, and
177. The radiochemistry of these shots resembles most closely the
earlier Soviet shots JOE 63 and JOE 72 (in 1958) and JOE 115 (in
1961), [text not declassified].
IV. HIGH-YIELD DEVICES
IN THE DECEMBER SERIES
a. 26 MT, Possibly 13 MT (JOE 184)
1. This device is compared with other Soviet shots in the
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13–30 MT range (JOEs 106, 144,
147, 148, and 156). [text not
declassified]
2. [text not declassified]
3. [text not declassified]
b. 6 MT Test (JOE 186)
This device appears as a follow-on to the Soviet tests JOEs 96, 97,
112, 136, and 137. [text not
declassified]
[Facsimile Page 9]
V. THERMONUCLEAR FUEL
EFFICIENCY AND FISSION-FUSION SPLIT
In the past, estimates of thermonuclear fuel efficiencies have been
based largely on the ratios of heavy element products. The amount of
Be–7 (made by deuterons reacting with Li–6) has been used in
conjunction with the estimated fuel efficiency to infer the
fission-fusion split. [text not declassified]
attention has been given recently to the amount of Li–6 found in the
debris as a supplementary measure of efficiency.
In addition the relationship “Be–7 per thermonuclear reaction” vs.
efficiency has been reviewed both theoretically and experimentally
(based on data from US tests) and some changes have been made in the
interpretation of this measurement. [text not
declassified]
[text not declassified] The newly available
Li–6 data constitute a useful additional criterion of thermonuclear
fuel efficiency. A more thorough review of these changes is planned
and the results will be incorporated in later evaluations.
[Facsimile Page 10]
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VI. SENSITIVITY OF THE
REPORT
We have been enjoined by a Presidential memorandum to caution each
person having access to the report that it contains particularly
sensitive information and is to be protected accordingly.
H.A. Bethe
Chairman, Foreign Weapons Evaluation
Group
