Maintaining Nuclear Weapons

                      Safe and Reliable Under a CTBT


                            Richard L. Garwin

                 Senior Fellow for Science and Technology
                  Council on Foreign Relations, New York


                           IBM Fellow Emeritus
                          IBM Research Division
                               P.O. Box 218
                        Yorktown Heights, NY 10598

                           Tel: (914) 945-2555
                           fax: (914) 945-4419
                      Email: RLG2 at
                  Many papers at

                  "The Comprehensive Test Ban Treaty and
                     US National Security Interests"

                           AAAS Annual Meeting
                            San Francisco, CA

                            February 16, 2001

       ABSTRACT.  I  discuss  nuclear  weapons  in general and U.S.
       thermonuclear weapons in particular.  These have been proven
       by  nuclear  explosive  development  tests  and   production
       verification tests, and need to be maintained for several or
       many  decades  without  further  nuclear  explosion testing,
       under  the  zero-threshold  Comprehensive  Test  Ban  Treaty
       (CTBT).  The basis for stockpile stewardship has always been
       a  strict  surveillance  program  by  which  eleven  nuclear
       weapons of each type  are  now  removed  annually  from  the
       stockpile  and inspected; one is destructively dismantled by
       the nuclear weapon laboratories.   Most of the  4000  or  so
       parts  of  a nuclear weapon can be thoroughly tested without
       nuclear  explosions  and  may  not  even  be  used   in   an
       underground nuclear test.

       The   weapons   can  be  maintained  safe  and  reliable  by
       remanufacture of the components-- the primary and  secondary
       nuclear explosives.  The Science-Based Stockpile Stewardship
       Program  (SBSSP)  provides  increased  understanding  of the
       necessity for remanufacture,  thereby  permitting  delay  in
       remanufacture,   in   some  cases,  because  inspection  and
       analysis shows that a particular age-related defect  is  not
       significant.    The  role of advanced computation facilities
       (teraflop computers), new flash  radiographic  systems,  and
       the  National  Ignition  Facility  will be evaluated for the
       Stockpile Stewardship Program.    The  surest  way  to  lose
       confidence  in the nuclear weapon stockpile is to orient the
       Stockpile Stewardship Program toward the introduction of new
       designs of the nuclear components.   The goal of  the  SBSSP
       should  be  to maintain the weapons as reliable as they were
       during the days of nuclear testing.   Historically,  weapons
       are  not  most  reliable  when  they  first enter stockpile,
       because of infant mortality.

       Of the other four  nuclear  weapon  states  under  the  NPT,
       France  and Britain appear to be emulating the United States
       in the SBSSP, while Russia and China are more likely to rely
       on scheduled remanufacture.  Either way they will be able to
       maintain a stockpile of  proven  nuclear  weapons  safe  and
       reliable for many decades or centuries.  The essential point
       is  not  to  make  changes,  even  multiple relatively small
       changes, that will eventually lead to lack of confidence.

       1046MNWS          021501MNWS Draft 3 Final          02/16/01


       Three important aspects of the analysis of cost and benefits
       of a Comprehensive Test Ban Treaty (CTBT) are:

       o   Can U.S. nuclear weapons be maintained safe and reliable
           without nuclear explosion testing?

       o   Is  there  a  non-proliferation  benefit  to  the United
           States in limiting nuclear weapons to those  that  might
           be developed without testing?

       o   Can  the  CTBT  be  adequately verified?   What kinds of
           nuclear weapons might be developed by experienced and by
           inexperienced states below the limit of detectability of
           the  International  Monitoring  System  and   the   U.S.
           unilateral capabilities?

       In this talk, I treat only the first(1) of these topics.


       I have been involved with building and testing U.S.  nuclear
       weapons  from 1950 to the present day, so what I am about to
       tell you  is  limited  by  what  can  be  said  legally  and

       All  nuclear  weapons  are based on a fission chain reaction
       carried by neutrons.  In a nuclear weapon,  a  supercritical
       mass  of  fissionable  material  needs to be assembled, such
       that a few fast  neutrons  introduced  will  cause  fission.
       Since  2.5  to 3.5 neutrons are emitted per fission in U-235
       or Pu-239, in an infinite medium each  neutron  disappearing
       gives  rise  to  about two new net neutrons, and the neutron
       population (and energy density due  to  fissions  that  have
       occurred)   grows   exponentially   as   e&alpha.t.      The
       "infinite-medium &alpha." corresponds to no loss of neutrons
       from the assembly.    For  a  mass  that  is  just  (prompt)
       critical,  the  neutron population remains constant, and the
       fission energy density increases linearly with  time  rather
       than exponentially.

       The  &alpha.  for an infinite medium increases linearly with
       density, since the time between generations depends  on  the
       mean  free  path  of  the  neutrons,  which  is inversely as
       density.   Finally, for  any  geometrical  configuration  of
       fissionable material (even including a reflector of neutrons
       such  as  beryllium  or uranium-238), the amount of material
       required to form a critical mass is inversely as the  square
       of the density.

       THE  "GUN-TYPE"  NUCLEAR  WEAPON.  The  nuclear  weapon that
       destroyed Hiroshima August  5,  1945,  was  a  gun-assembled
       U-235  bomb yielding some 13 kilotons (kt) of high-explosive
       equivalent energy-- 13 x 4 TJ.  It weighed some 8000 lbs and
       is reported to have contained some 60 kg of highly  enriched
       uranium.    Just as important as a supercritical assembly to
       make a nuclear weapon is  the  sub-critical  nature  of  the
       material up to the moment a chain reaction is desired.

       U-235  has  such small spontaneous neutron emission (and the
       flux of neutrons from cosmic rays is sufficiently low), that
       a normal artillery  piece  with  a  projectile  velocity  of
       300 m/s  will assemble two sub-critical chunks of U-235 into
       a single supercritical mass in a time short enough that  the
       probability  of  pre-initiation is acceptably small-- moving
       from the just-critical assembly to the  maximum  criticality
       in a time that might be 0.2 m/300 m/s = 7 ms.  The Hiroshima
       design  had  a  neutron  generator  to  initiate  the  chain
       reaction at maximum criticality. The complete fission of one
       kg of material liberates the equivalent of 17 kt.

       THE IMPLOSION WEAPON. By placing the U-235 or  plutonium  at
       the  center  of  an  assembly  of high explosive, in which a
       converging spherical detonation wave is launched, even solid
       metal can be compressed so  that  a  subscritical  mass  can
       rapidly  be  made supercritical.  With a detonation speed of
       0.6 cm/microsecond,  a  10  microsecond  interval   may   be
       appropriate  for  this compression.  A neutron generator may
       be optional for  a  gun-assembled  nuclear  weapon,  if  the
       projectile  can  be  stopped  so that the supercritical mass
       awaits a cosmic-ray neutron,  but  a  neutron  generator  is
       essential  for  the implosion weapon, which will just bounce
       and rapidly become subcritical.   But  the  gun  is  totally
       unsuitable  for plutonium, which, with its nominal 6% Pu-240
       content and a 6-kg mass in the Nagasaki  bomb,  emits  about
       0.36  neutrons  per  microsecond  by  virtue  of spontaneous
       fission of the Pu-240.

       Because plutonium has both a  larger  fission  cross-section
       and   more   neutrons   emitted  per  fission,  and  density
       comparable to uranium, smaller amounts of Pu are needed than
       U-235.  The 6-kg ball of the Nagasaki bomb gave a  yield  of
       almost 20 kt.

       EVOLUTION  OF  FISSION  WEAPONS.  Implosion  is the assembly
       method of choice for U-235 as well as Pu.  By 1951, with the
       aid of nuclear explosion tests, the U.S.   had produced  and
       stockpiled  the  "half-size"  implosion  weapon--  the Mk-7,
       weighing 1800 lbs and with a yield considerably larger  than
       the  20 kt of the Nagasaki bomb.  South Africa did build six
       gun-assembled U-235 weapons,  without  any  explosive  test,
       just  as the United States did not test its gun before using
       it on Hiroshima.  U.S. nuclear weapons (and perhaps those of
       the  other  four  Nuclear  Weapon  States  under  the   1970
       Non-Proliferation   Treaty,   NPT)  now  consist  of  hollow
       plutonium shells surrounded by high explosive.    The  shell
       can  be  accelerated  and  then  abruptly  arrests itself by
       symmetry,  leading  to  greater  compression  than  can   be
       achieved  in a solid sphere.  Accordingly, the Pu content in
       a U.S. nuclear weapon is as little as 4 kg.

       BOOSTED FISSION WEAPONS. In 1951, the  United  States  first
       tested  "boosting."    In the modern boosted fission weapon,
       deuterium  and  tritium  gas  are  present  in  the   hollow
       plutonium  shell  at  the time of implosion.  The d-t gas is
       compressed and then suddenly heated by the fission reaction,
       which provides thermonuclear reactions between d and  t  (at
       about 100 times the rate of that between d and d).  Each d-t
       reaction   yields   a  14-MeV  neutron,  which  has  a  high
       probability of causing fission in the surrounding Pu,  which
       in  turn contributes 150 MeV to the energy of the explosion.
       Thus, it is not the energy from thermonuclear boosting,  but
       the  additional  flash of neutrons and fission that "boosts"
       the fission chain reaction to a higher level and  multiplies
       the energy release.

       In  U.S. nuclear weapons, the deuterium and tritium are kept
       in high-pressure steel gas "bottles"  and  provided  to  the
       hollow  plutonium  shell  after  the weapon is launched, but
       before the high explosive is fired.  The plutonium shell  is
       surrounded  by  a  welded  metal  enclosure; the whole metal
       assembly is a "pit", as it was called in the  earliest  days
       of implosion weaponry.

       TWO-STAGE  THERMONUCLEAR WEAPONS. In 1951, Edward Teller and
       Stanislaw Ulam at the Los Alamos  Scientific  Laboratory  in
       New  Mexico  published  a  classified  paper  on  "radiation
       implosion," (an officially declassified term) in  which  the
       energy of the x-rays in the thermal electromagnetic field is
       used   to   compress  and  prepare  a  secondary  charge  of
       thermonuclear  fuel  and  to  ignite  it  by  bringing   the
       compressed  fuel to a high temperature.  The boosted fission
       primary and the secondary are contained in a radiation case,
       of  material  of  a  high atomic number, such as uranium.(2)
       These  are  called  "two-stage"  thermonuclear  weapons   to
       distinguish  them from other approaches in which substantial
       amounts of fusion fuel are in close proximity to the fission

       Some orders of magnitude may be of interest here.    At  the
       high   temperatures  resulting  from  a  nuclear  explosion,
       everything within the bomb is a plasma-- only  the  heaviest
       nuclei have even one electron attached.  The thermal kinetic
       energy  is  thus  3/2 kT  for each of the particles, and the
       particles are by number predominantly electrons.   So  there
       is  about  one  mole of electrons per two grams of material.
       If 17 kt of energy were to be confined to 6 kg  of  Pu,  the
       temperature  (ignoring the black-body radiation field) would
       be 170 keV.   But this same 70 TJ  of  energy  is  far  from
       enough  to heat the vacuum(!) to 170 keV.  Indeed, the black
       body energy density in the electromagnetic field goes as T4,
       and is about 13 GJ/liter at T = 1 keV, or  about  5 GJ/0.4 l
       at  1 keV.    The initial volume of 6 kg of Pu at 15 g/cc is
       just 0.4 l.  The yield of 70 TJ would heat this same  volume
       to 11 keV, so that the matter temperature would also be held
       to 11 keV.

       In  fact, the opacity even of Pu is sufficiently low at such
       temperatures that much of the black body radiation leaks out
       to  fill  the  radiation  case  at  a   considerably   lower
       temperature--  for instance, lower by the fourth root of the
       ratio of the volumes.   Thus if the  radiation  case  has  a
       volume  of  50 l,  the ratio of volumes is some 125, and the
       temperature could rise to as much as 3 keV.

       Since a given energy density of radiation has almost as much
       pressure as the same energy density in matter, the  pressure
       squeezing  on  the secondary charge corresponds in this case
       to some  70 TJ/50 l  or  about  1.4 TJ/l.    High  explosive
       provides  something  like 4 MJ/l, so the radiation implosion
       proceeds with a pressure some 0.3 million times that of high

       RECAPITULATION. The United States has roughly ten  types  of
       nuclear  weapons in its stockpile of perhaps 12,000 warheads
       and bombs.    All  are  radiation  implosion  weapons,  with
       gas-boosted  hollow  plutonium primaries, and secondaries as
       described.   The secondary fuel is  normally  solid  lithium
       deuteride (LiD).

       The  nuclear  explosion  is  obtained when electrical firing
       pulses are applied with sufficient simultaneity  to  all  of
       the  electric  detonators,  which in turn detonate a booster
       pellet  and  then  the  main  charge  of   high   explosive.
       Initially,   a  spherical  converging  detonation  wave  was
       obtained from the multiple diverging  detonation  points  by
       the use of "lenses" of various types-- initially of fast and
       slow  explosives,  later  with  "ring  lenses" to reduce the
       enormous mass of the lens region, and still later with  "air
       lenses"  or  other  means to obtain a detonation wave of the
       appropriate shape.   The d-t  gas  from  the  reservoirs  or
       bottles enters the pit via an explosively operated valve.


       A  1979  memo from the Director of the Los Alamos Scientific
       Laboratory to DOE headquarters,(3) states:

            "Will the nuclear device work?   The reliability  of  a
            nuclear  weapon  (that  has  been tested) is determined
            primarily  by  the  reliability  of   its   non-nuclear
            components  and  not  by  its nuclear components.   The
            non-nuclear  components  can  be  demonstrated  to   be
            statistically reliable to a desired level, normally 98%
            or  better, by doing a sufficient number of non-nuclear
            local tests.  This procedure has not  been  altered  by
            the  Threshold  Test Ban Treaty and will not be altered
            by the Comprehensive Test Ban Treaty.  The  reliability
            of  the  nuclear performance of a weapon is a different
            matter.  It is not a statistical quantity.  After a few
            key nuclear tests are conducted, it is the judgment  of
            the   Laboratories,  based  upon  30  years  of  design
            experience, that the nuclear performance is  guaranteed
            if  the  non-nuclear components function as desired and
            the nuclear components are maintained in their as-built
            condition.  A very important conclusion, then, is  that
            there   has   been   no  reduction  in  nuclear  weapon
            reliability as a result of the TTBT and that there will
            be none under a CTBT  if  we  utilize  current  nuclear
            systems  which  have  been tested or utilize previously
            tested nuclear components as subsystems."

       In  the  United  States,  nuclear  weapons   are   designed,
       developed,  manufactured, and cared for by the Department of
       Energy.  In a sense, they are loaned or transferred  to  the
       military   to  be  ready  for  delivery  as  bombs,  missile
       warheads, or (in  the  old  days)  nuclear-armed  torpedoes,
       anti-aircraft  rockets,  atomic  demolition charges, and the
       like.  The Los Alamos National Laboratory and  the  Lawrence
       Livermore  National Laboratory, both operated for DOE by the
       University  of  California,  have  responsibility  for   the
       nuclear components-- roughly those within the radiation case
       of a thermonuclear weapon.  Sandia National Laboratory, with
       its  main  facilities at Albuquerque, NM, and a smaller site
       at  Livermore,  has  responsibility  for   the   non-nuclear
       components,  such  as batteries, arming, firing, and fusing,
       Prescribed  Action  Links  or  other   use-control   system,
       state-of-health  monitors,  and  the  like.    Of  the  4000
       components of a typical bomb, all but  a  few  are  Sandia's

       In  analyzing  the  difference between an era of underground
       nuclear tests and the CTBT, it must be recognized that  most
       of  these  non-nuclear  components  are not exercised at all
       during an underground  nuclear  test.    For  instance,  the
       environmental  sensing  system  that  ensures that a nuclear
       weapon will not  explode  until  it  has  been  through  the
       appropriate  accelerations,  coast, and the like, is clearly
       not applicable to an underground test.  Such components  for
       the  most  part  are  testable on the bench.  Those that are
       destroyed by their activation  (such  as  explosively  fired
       valves or thermal batteries) are tested in large quantities,
       so  that  those  that  have  not  been tested are assured of
       performance as random selection from a  lot  that  has  been
       tested  to  ensure  the  desired  confidence in reliability.
       Explosive detonators (in  the  first  implosion  weapons,  a
       bridge  wire  of noble metal fired by a substantial pulse of
       electrical energy) were initially used  in  the  almost  100
       lenses of an early nuclear weapon.  Many thousands of bridge
       wires  had  to  be  fired  without  fail  in  order  to have
       confidence in adequate reliability that  not  a  single  one
       would miss when fired "for effect."

       The Stockpile Stewardship Program has two goals:  (I) a safe
       and  reliable stockpile of nuclear weapons of existing type,
       and (II) a viable community to resume weapon development and
       testing in case the Comprehensive Test Ban Treaty (CTBT) era
       ends.  I have been involved in reviewing and  assessing  the
       program  for the Department of Energy, primarily as a member
       of the JASON group of consultants to the government.    Some
       of  our  reports  are available as unclassified documents on
       the Web:(4)

       I believe the relevant question is whether  nuclear  weapons
       can  be  maintained as safe and reliable as they were before
       the  CTBT  was  signed  in   1996   (and   even   before   a
       congressionally  mandated moratorium on nuclear testing took
       effect in 1992).  Although much of the emphasis,  publicity,
       and  budget  go  to the advanced facilities and capabilities
       involved  in  stockpile  stewardship,  such  as  ASCI   (the
       Accelerated  Strategic  Computation Initiative, at the three
       weapon  laboratories);  DAHRT  (the  Dual-Axis  Hydrodynamic
       Radiographic facility, at Los Alamos); and NIF (the National
       Ignition Facility, at Livermore); the core of the program is
       really  an  enhanced  surveillance  and in the capability to
       remanufacture the weapons in the stockpile, as needed.

       Under  the  Enhanced Surveillance Program, 11 copies of each
       of  the  ten  types  of  nuclear  weapons  in  the  enduring
       stockpile   are  removed  each  year  and  radiographed  and
       otherwise inspected.  One of each is  totally  disassembled,
       and  the pit and secondary cut open for inspection.  Samples
       of the high  explosive  are  removed  and  tested,  and  the
       plutonium  pit is carefully inspected.  Items of concern are
       noted and eventually may  be  categorized  as  "actionable",
       leading  to  some  kind of remedy on the entire stockpile of
       such weapons.  Problems might be as simple as a loose screw,
       excessive friction on a mechanical  component  such  as  the
       use-control  system,  or  incipient  corrosion on some metal
       part.  Plutonium and uranium both react  with  hydrogen  and
       with water.

       Plutonium  pits  were  formerly manufactured at Rocky Flats,
       CO, now closed.  A replacement small-scale pit manufacturing
       facility is being qualified  at  TA-55  (Los  Alamos)  which
       might  produce  on  the  order  of 30-50 pits per year.  The
       United States has experience with pits on the  order  of  30
       years  old,  which  show  no signs of deterioration, and the
       general feeling  from  recent  inspections  and  from  aging
       experiments  done  with  higher  Pu-238  content  (78  years
       half-life vs. 24,000 for Pu-239) is that  current  pits  are
       not  expected  to deteriorate for 60-90 years or more.  Note
       that the lack of a pit production facility  is  not  a  CTBT
       issue; it would be the same problem whether or not one could
       use nuclear explosion testing.

       Without  being excessively tedious, I note the conclusion of
       the  JASON  studies  (and  laboratory  assessments)  that  a
       secondary charge, if driven with the design radiation energy
       in  the  radiation  case,  will  provide  the overall energy

       Given the ability to test-fire  detonators  and  to  inspect
       them  carefully in the disassembly process, and also to fire
       samples of the high explosive-- and even one per year of the
       explosive in an actual weapon-- the major uncertainty in the
       performance of a nuclear weapon comes in the details of  the
       boosting process.  This is affected by how much plutonium is
       mixed with the d-t gas by the implosion itself, and that is,
       in  turn,  affected  by the surface finish and corrosion (if
       any) of the plutonium surrounding the d-t gas.

       To address this question, so-called subcritical  experiments
       are being performed at the Nevada Test Site, specifically to
       monitor  the  ejecta  produced  when  a  plutonium  plate or
       partial shell is subject to  high  explosive  shock  on  the
       other side.

       What  is  actually being done in the Science-Based Stockpile
       Stewardship Program (SBSSP)?   In  addition  to  the  normal
       "custodianship"  sketched  above,  the  SSP  adopted  by the
       Department  of  Energy  and  its  laboratories  is  "science
       based."    In  part,  this adds assurance that the impact of
       defects or  artifacts  discovered  during  the  surveillance
       process  will  be  fully  understood.   The experimental and
       analytical capabilities, in  principle,  could  be  used  to
       assess defects of substantial magnitude, and might show that
       remedial action was not needed until they had grown further.
       By  delaying  replacement  or  refurbishment,  there  is  in
       principle here  the  possibility  of  saving  money.    But,
       especially  with  small numbers of weapons in the stockpile,
       the acquisition of these capabilities might be  more  costly
       than early or routine replacement of the warheads.

       Specifically,  DAHRT  extends  the conventional pulsed x-ray
       facility  used  for  dynamic  imaging  of  actual  implosion
       systems   (with  the  fissionable  material  replaced  by  a
       simulant-- for instance, depleted uranium).  The first  axis
       is operating in Los Alamos, and the second will be available
       in  about  a  year--  imaging  at right angles, and with the
       possibility  of  having  four  pulses  spread  over  a   two
       microsecond   interval.    These  flash  x-ray  images  were
       initially captured on film, but are now caught on  an  array
       of scintillation crystals-- electronic imaging.  DAHRT is an
       excellent  tool  of  exploring  new weapon designs that have
       been developed by analysis and computation, as well  as  the
       assessment  of the influence of flaws that may be discovered
       in the surveillance program.

       No  nuclear  weapon  in  the  stockpile  was  designed  with
       computational  capabilities  exceeding the 500 MHz processor
       now common in your desktop PC.   Yet the  ASCI  program  has
       already  resulted in systems at each laboratory operating at
       the three tera-operation per  second  (TOPS)  level.    Such
       facilities  are  used  in the SBSSP to try to understand the
       fundamentals of  detonation  of  high  explosives,  and  the
       details of hydrodynamics, neutron propagation, and the like.
       The  need  for such enormous computing capabilities is often
       stated to derive from the three-dimensional (3-D) nature  of
       a  flawed  or  aged  nuclear  weapon,  in  contrast with the
       strictly  2-D  modeling  that  suffices  for   a   two-stage
       radiation  implosion--  which,  after  all,  has  an axis of
       symmetry.  In 2-D, the dynamics can be analyzed by assigning
       every volume element a variable radius  and  axial  position
       (R,Z),  and  thus modeling the system as elementary rings of
       material.   Of course,  at  every  R,Z  there  are  material
       properties--  identity, density, temperature(s), velocities,
       etc.  Designs were done on such a  2-D  basis,  even  though
       turbulence, or instabilities at interfaces have no reason to
       respect the 2-D assumption.

       Furthermore,  in  a  flawed  system,  there  is no reason to
       believe  that  a  flaw  will  automatically  have  azimuthal
       symmetry--  a  nick  or  gap in the R-Z plane, for instance,
       must   be   modeled   (at    least    locally)    in    3-D.
       Straightforwardly,  if  a  1-D  spherical implosion would be
       modeled now with 1000 radial points, and a 2-D  system  with
       1000 x 1000,  then  a  3-D  model would need an extra factor
       1000-- a billion points.

       The National Ignition Facility at Livermore (NIF)  has  been
       in the news recently, with technical problems and budget and
       schedule difficulties.  It consists of 192 laser beam lines,
       intended  to focus more than 1 MJ of short-pulse laser light
       into a mm-size gold cylindrical radiation case (or Hohlraum)
       where they will equilibrate to produce soft  x-rays  with  a
       black  body  radiation  temperature  on the order of 300 eV.
       Considerably  lower  in  temperature  than  the  black  body
       radiation  available  from a nuclear primary, and hence much
       lower in energy density (remember T4!), NIF will nonetheless
       allow validation on the sub-mm scale of radiation  flow  and
       implosion calculations relevant to secondaries.

       At  Sandia Albuquerque, the "Z-pinch" has produced more than
       1 MJ of thermal x-rays, filling a larger Hohlraum  than  NIF
       with  a  black  body  temperature  of more than 200 eV. Such
       results are obtained by imploding  a  cylindrical  shell  of
       hundreds  of  fine  wires  by  the  self-magnetic  field  of
       20 megamp currents.  Interesting results have been  obtained
       not  only  on radiation flow but also by the use of magnetic
       pressure  to  drive  flyer  plates  to  produce  shocks   in
       materials  of  relevance  to  nuclear  weapons.    In  other
       experiments on the Z machine, the magnetic pressure is  used
       to  provide  isentropic  compression  of  materials, such as
       deuterium, to explore their equation of state.

       THE CTBT AND THE STEWARDSHIP PROGRAM. My judgment is evident
       from the comments above-- the enhanced surveillance  program
       and  a  remanufacturing  capability,  and people to carry it
       out, will serve to maintain the  primary  and  secondary  of
       nuclear  weapons  in  good  shape  for  many decades or even
       centuries.  Atoms do not age, and a weapon  rebuilt  in  the
       year  2100  (using perhaps rather archaic processes) will be
       just as good as when it was manufactured in 1985. Recall the
       1979 letter from the director of Los Alamos.

       The facilities that get all the attention, in my view, serve
       primarily to attract, challenge, and validate the people who
       will be involved in  the  surveillance  and  remanufacturing
       efforts.    But  it would be totally incorrect to equate the
       ability to obtain "ignition" of d-t gas or ice in  NIF  with
       confidence in the U.S. stockpile of nuclear weapons.  And it
       would  be  equally  wrong  to  assess  a  failure to achieve
       ignition (for whatever reason) as impugning in any  way  the
       capability of our stockpiled weapons.

       In  fact,  new-design  weapons  entering  the stockpile have
       sometimes had an infant mortality problem, so that  existing
       and  remanufactured  weapons are likely to be more reliable,
       and we should have more confidence in them than if  we  were
       replacing them by weapons of new design.

       The  important  point is that nuclear explosive tests are of
       little use in maintaining a stockpile of weapons of existing


       The inability to test with nuclear explosion yield does  not
       inhibit  the United States from maintaining its stockpile of
       existing nuclear weapons safe and reliable.  And the same is
       true for the other four nuclear states with fully  developed
       and  tested  nuclear  weapons  in their stockpiles-- Russia,
       Britain, France, and China.

       1   In  a  paper  for the American Geophysical Union meeting
           May 31, 2000, (at, I discuss the
           other two topics as well.
       2   I contributed to  the  design  of  the  first  radiation
           implosion,  the  MIKE  test  of  November 1, 1952, which
           yielded almost 11 megatons (MT) from a secondary  charge
           of liquid deuterium surrounded by uranium.
       3   Harold M. Agnew to J.K. Bratton, February 13, 1979.
       4   At (search for "JASON" or "JSR").