August 26, 1998

       Reactor-Grade  Plutonium  Can  be  Used to Make Powerful and
       Reliable Nuclear Weapons:  Separated plutonium in  the  fuel
       cycle must be protected as if it were nuclear weapons.


                           Richard L. Garwin(1)
                 Senior Fellow for Science and Technology
                  Council on Foreign Relations, New York
                         Draft of August 26, 1998
            FAX: (914) 945-4419; Email: rlg2 at

       As access to technology advances throughout the  world,  the
       barrier  to the acquisition of nuclear weapons by terrorists
       or nations is more and more  the  barrier  to  weapon-usable
       fissionable  material--  traditionally high-enriched uranium
       or "weapon-grade" plutonium.  Even a modest  nuclear  weapon
       delivered  by aircraft, missile, ship, or truck can threaten
       the lives of 100,000 people.  Therefore it is  important  to
       understand  whether reactor-grade plutonium from the nuclear
       fuel cycle-- typically 65%  fissile  (by  thermal  neutrons)
       compared  with  93%  fissile for weapon-grade material-- can
       readily be used to create nuclear weapons.    Unfortunately,
       the  answer  is  that  it  can be so used.   The conclusion,
       therefore, is that separated reactor-grade plutonium must be
       guarded in just the same way  as  if  it  were  weapon-grade
       plutonium  if  it is not to contribute greatly to the spread
       and possible use of nuclear weaponry.

       The  facts  required  to  judge the utility of reactor-grade
       plutonium (R-Pu) for use in nuclear weapons were first  made
       widely available in 1993 by J.  Carson Mark.(2) The isotopic
       composition  of  reactor-grade  plutonium  as  compared with
       weapon-grade Pu (W-Pu), results in four differences  between
       R-Pu and W-Pu:

       1.  The "bare sphere" critical mass for R-Pu is about 13 kg,
       vs. 10 kg for W-Pu (both alpha-phase metal of  density  19.6

            As  regards  the  usability  of  R-Pu  to  make nuclear
            weapons, the larger critical mass for R-Pu  means  that
            about  30% more R-Pu metal is needed than W-Pu to build
            a weapon.

       2. The alpha-particle radioactivity of R-Pu contributes 10.5
       watts of heat per kg R-Pu, vs. 2.3 W/kg for W-Pu.

            The  greater  heat  evolution  (68  watts  for  half  a
            bare-sphere  critical  mass  of  R-Pu, vs. 11 watts for
            half a bare-sphere critical mass of  W-Pu)  means  that
            the  thick  high-explosive that surrounds the plutonium
            and any additional metal shells in a  simple  implosion
            weapon  will  overheat if R-Pu is substituted for W-Pu.
            Mark estimates the amount of  aluminum  heat  conductor
            that  would  suffice  to  cool  the  R-Pu.    So-called
            In-Flight Insertion devices that  were  used  in  early
            nuclear  weapons  would  allow  adequate cooling of the
            plutonium until it is inserted into the high  explosive
            a few minutes before detonation.

       3.  The continuing neutron emission from spontaneous fission
       of Pu-240 contributes 360 neutrons per second per g of R-Pu,
       vs. about 66 neutrons per second per g of W-Pu.

            According to Mark, as the fissionable material is being
            compressed so  that  it  becomes  critical,  a  neutron
            injected  at  the  worst  possible time would cause the
            earliest model of implosion weapon to have an explosive
            yield between 1 and 2 kilotons (that is,  between  1000
            tons  and  2000  tons  of  high  explosive such as TNT)
            rather than the full yield of  some  20  kilotons  when
            neutron  injection is optimally timed to occur near the
            time of maximum criticality.  In contrast, in 1972  the
            U.S.  Government  officially  revealed  that  the  U.S.
            possessed more advanced  nuclear  weapons  whose  yield
            would  not  be diminished by the injection of a neutron
            at no matter what instant of time.  With this  type  of
            design,  the spontaneous neutrons from R-Pu would in no
            way diminish the reliability or the expected yield.

       4. A mass of R-Pu provides greater radiation exposure  to  a
       person  than  does  W-Pu.   At a distance of 1 meter from an
       unshielded 6-kg mass of each,  the  radiation  field  is  30
       millirem  per  hour  for  R-Pu,  vs. 5 millirem per hour for

            The greater external radiation from a weapon  component
            of  R-Pu compared with that of W-Pu means that the dose
            of 5 rem long deemed acceptable for a radiation  worker
            would  be  received  in 160 hours one meter from a bare
            core of R-Pu, vs. 1000 hours for a core of W-Pu.

       These facts are interpreted by various bodies as follows:

       Mark 1993:
       "The difficulties of developing an effective design  of  the
       most  straightforward  type are not appreciably greater with
       reactor-grade plutonium than those that have to be  met  for
       the use of weapons-grade plutonium."

       CISAC(3) 1994:
       "In short, it  would  be  quite  possible  for  a  potential
       proliferator  to make a nuclear explosive from reactor-grade
       plutonium using a simple design that  would  be  assured  of
       having  a  yield  in the range of one to a few kilotons, and
       more using an advanced design.  Theft of separated plutonium
       whether weapons-grade or reactor-grade, would pose  a  grave
       security risk."

       American Nuclear Society Special Panel Report(4) 1995:
       "We  are aware that a number of well-qualified scientists in
       countries that have not developed nuclear  weapons  question
       the  weapons-usability  of  reactor-grade plutonium.   While
       recognizing that explosives have  been  produced  from  this
       material,  many  believe  that  this  is  a feat that can be
       accomplished only by an advanced nuclear- weapon state  such
       as  the United States.  This is not the case.  Any nation or
       group capable of making a nuclear  explosive  from  weapons-
       grade  plutonium  must  be  considered capable of making one
       from reactor- grade plutonium."

       U.S. Department of Energy(5) 1997:
       "Proliferating  states   using   designs   of   intermediate
       sophistication  could  produce  weapons  with assured yields
       substantially higher than the  kiloton-range  made  possible
       with a simple, first- generation nuclear device."   and

       "The  disadvantage of reactor-grade plutonium is not so much
       in the effectiveness of the nuclear weapons that can be made
       from  it  as  in  the  increased  complexity  in  designing,
       fabricating, and handling them.  The possibility that either
       a  state  or  a  sub-national  group  would  choose  to  use
       reactor-grade  plutonium,  should   sufficient   stocks   of
       weapon-grade  plutonium  not be readily available, cannot be
       discounted.     In   short,   reactor-grade   plutonium   is
       weapons-usable,  whether by unsophisticated proliferators or
       by advanced nuclear  weapon  states.    Theft  of  separated
       plutonium,  whether  weapons-grade  or  reactor-grade, would
       pose a grave security risk."

       As an author of the 1994 CISAC report,  I  helped  formulate
       the  statement  that  I quote above.  What should the reader
       believe?    Individuals  are  often  skeptical  of  official
       statements,  and  it  is  often  said "Those who know, don't
       speak; and those who speak, don't know."   But that  is  not
       the  case  with  the  members of CISAC, all of whom endorsed
       this  statement;  they  both  know  and  speak.      It   is
       particularly  to  be  noted that among the Committee are the
       following physicists who  are  knowledgeable  about  nuclear
       weapons  and  who  reviewed a secret study done for CISAC by
       the  Los  Alamos  National  Laboratory  and   the   Lawrence
       Livermore  National  Laboratory--  the  United  States'  two
       nuclear weapon design laboratories.   Besides myself,  these
       include   John  P.  Holdren,  Michael  M.  May,  and  W.K.H.
       Panofsky.    May  is  a  former  director  of  the  Lawrence
       Livermore National Laboratory.


       The United States has long opposed  the  spread  of  nuclear
       weapons and nuclear weapons technology to additional states,
       and especially to terrorists.  This position is that adopted
       by  almost all of the nations of the world, including Japan,
       as embodied in the Non- Proliferation  Treaty  (NPT),  which
       entered  into force in 1970. Now 185 nations have signed the
       NPT, which makes it  illegal  to  transfer  nuclear  weapons
       technology  from  a  nuclear weapons state, and also illegal
       for a non-nuclear weapons state to acquire nuclear  weapons.
       At the same time, the NPT encourages the transfer of nuclear
       technology  for  civil  uses,  and  thus  the  technology of
       nuclear reactors and fuel fabrication and  reprocessing  can
       be  communicated  to  any state that is a member of the NPT,
       whether a nuclear weapon state  or  a  non-  nuclear  weapon
       state,  provided that safeguards are in place inhibiting the
       diversion of weapons-useable materials.   According  to  the
       NPT,  it  is  illegal  for the United States to explain to a
       non-nuclear weapon state how to make a nuclear  weapon,  and
       that  is  why  details  of how to fabricate a nuclear weapon
       from reactor-grade plutonium cannot  be  published  here  or
       communicated to any non-nuclear weapon state.

       In  1976  the  United  States  decided  that  releasing some
       additional information about nuclear weapons would  actually
       aid  in  preventing  their  spread-- the purpose of the NPT.
       The result was a  1976  briefing(6)  by  the  Department  of
       Energy  to  nations  with  active nuclear power programs, so
       that they should understand  the  utility  of  reactor-grade
       plutonium  in  the  fabrication of nuclear weapons, and thus
       adopt measures to protect and account for plutonium in spent
       fuel downloaded from nuclear power reactors.   This was  the
       information  published  more  fully  in  the 1993 article by

       The nations signing the NPT, and the nuclear power  industry
       worldwide,  would  be  delighted  if  plutonium  produced by
       nuclear reactors that operate to generate electrical  energy
       were  not  usable to make nuclear weapons, but the facts are
       otherwise,  as  explained  in   the   previous   paragraphs.
       Nevertheless,  some interpret their own wishes as the facts;
       and beyond those who are confused in this fashion there  are
       advocates and publicists (either without the ability to form
       their   own   judgment   or   who   do   not  recognize  the
       responsibility to do so)  who  repeat  arguments  that--  if
       true-- would cut one possible link between nuclear power and
       nuclear weapons.

       My colleague, Ambassador Imai was an International Member of
       the  American  Nuclear Society Special Panel, which reported
       as I have quoted above.  The ANS panel  included  Harold  M.
       Agnew,  who  was  present in December 1942 at criticality of
       the first Fermi reactor, worked at Los Alamos to  build  the
       atomic  bomb,  and  was  director of the Los Alamos National
       Laboratory for 10 years.    But  Ambassador  Imai  has  more
       recently expressed doubts about the utility of reactor-grade
       plutonium for making nuclear weapons.  As I read closely his
       remarks(7)   I   see   that   he   suggests  that  the  four
       disadvantages of  reactor-grade  plutonium  discussed  above
       mean  that  nuclear explosives made from this material could
       not be reliable, might be "toy weapons", and that any nation
       (as distinguished from terrorists and  rogue  states,  which
       could  not  arm  themselves  with  nuclear  weapons) wanting
       nuclear weapons would "probably equip themselves with modern
       weapons, mainly thermonuclear bombs" instead of  "unreliable
       bombs  with reactor grade plutonium."  But the impact of the
       authoritative comments  that  I  have  quoted  (and  my  own
       view)(8) is that a nation could indeed make reliable fission
       weapons  (and  hence  the  "primaries"   for   thermonuclear
       weapons) by the use of reactor-grade plutonium.

       The  Summary  of  a  February  1998  report(9)  of the Royal
       Society of Britain, chaired by Sir Ronald Mason,  states  of
       the  U.K.  activity  in  reprocessing  fuel from its nuclear
       reactors and  from  those  of  foreign  customers  including

            "The  existence  of plutonium stocks, in whatever form,
            is  of  concern  on  two  counts:   radiotoxicity   and
            proliferation   risk.      Whilst  not  underestimating
            radiotoxicity risks, the  chance  that  the  stocks  of
            plutonium might, at some stage, be accessed for illicit
            weapons  production is of extreme concern.  The current
            stockpiling policy should  not  be  maintained  without
            careful study of alternatives."

       More directly, it observes:

            "The  surest  anti-proliferation  measure  is  to  stop
            reprocessing spent fuel and to reduce the  quantity  of
            separated plutonium in store."

       However I was troubled by the report's statement (p. 6):

            "The  critical  mass  of  fissile plutonium (Pu-239 and
            Pu-241)  needed  to  sustain  a   chain   reaction   in
            reactor-grade  plutonium may be <an order of magnitude>
            greater  than  for  weapons-grade   plutonium.      The
            reliability  and  yields  of  weapons  constructed from
            reactor-grade  plutonium   might   also   be   reduced.
            However,  an  experienced  weapons  designer could have
            confidence in a weapons system based on  reactor  grade
            plutonium  <with  85% fissile content>.   Reactor grade
            plutonium,  of   known   isotopic   composition,   must
            therefore   be  regarded  as  a  plausible  target  for
            determined terrorist groups or states wishing  to  make
            nuclear weapons."

       As should be clear from my own analysis, the portions I have
       surrounded  by  angular  brackets "<...>" are incorrect.  We
       have  noted  that   the   bare-sphere   critical   mass   of
       reactor-grade  plutonium  extracted  from  highly irradiated
       spent fuel  from  a  normal  pressurized  water  reactor  or
       boiling  water reactor operating at 43,000 megawatt-days per
       kg fuel is 13 kg-- only 30% (not the 100 kg which would be a
       factor 10 or "an order of magnitude") greater than the 10-kg
       critical mass  of  weapon-grade  plutonium.    And  this  is
       reactor-grade  plutonium  with  66% "fissile content".   The
       point is that "non-fissile" Pu-240 is fissionable  with  the
       fast  neutrons  that  carry  the chain reaction in plutonium
       metal; in fact, even pure Pu-240 has a critical mass  of  40
       kg--  smaller than pure U-235-- for use in a nuclear weapon.
       In a clarifying letter,(10) Sir Ronald Mason states that the
       "order  of  magnitude  greater"  critical  mass  refers   to
       plutonium  oxide,  as  compared  with  plutonium metal;   he
       writes also that he agrees  the  data  I  provide  above  on
       critical  mass, and notes further that the yield will depend
       somewhat on the precise isotopic composition.


       None  of  the  five  nuclear  weapon  states  (U.S., Russia,
       Britain, France, and China)  is  believed  to  have  in  its
       stockpile nuclear weapons made from reactor-grade plutonium.
       In  part  this  is  due to their light- water power reactors
       coming later than their nuclear weapons programs.   But  per
       unit  of  heat  removed generated in the reactor (which is a
       limiting characteristic and cost of a  plutonium  production
       program),  plutonium is best obtained by reprocessing at low
       burnup, and hence while it is still "weapon grade".  And  at
       higher  burnup, much of the Pu- 239 generated in the reactor
       is fissioned and thus lost.

       As Carson Mark made clear,  the  difficulties  in  making  a
       nuclear   weapon   with   reactor-grade  plutonium  are  not
       different  in  kind  than  those  involved  in  the  use  of
       weapon-grade  material.  Made of reactor- grade plutonium, a
       simple fission weapon a fraction of the  time  may  have  an
       explosion yield of 1000 to 2000 tons of high explosive-- the
       equivalent  of  1000 truck bombs going off simultaneously at
       one point, plus the effects of  nuclear  radiation;  but  it
       would  never  have a lower yield, and a fraction of the time
       it would have full design yield of 20 or 40  kilotons.    As
       for the "more sophisticated" designer, it is my own judgment
       that  not  only the five nuclear weapon states, but also the
       nuclear weapon establishments of India, Pakistan, and Israel
       are  capable  of  converting  reactor-grade  plutonium  into
       nuclear  weapons  that have similar yield and reliability to
       those made with weapon- grade plutonium.    (This  paragraph
       was  drafted  before  the  nuclear weapon test explosions by
       India and Pakistan in May, 1998).

       In conclusion, separated plutonium-- whether weapon grade or
       reactor grade-- poses a similar danger of misuse in  nuclear
       weapons  and  must  be provided similar physical protection,
       control, and accountancy.  This has been recognized  by  the
       International   Atomic   Energy   Agency   (IAEA)  from  its
       beginning-- all plutonium (except Pu-238 of isotopic  purity
       greater  than 80%) is regarded as equally hazardous from the
       point of view of diversion to nuclear weaponry.


       I am a member of the Committee on International Security and
       Arms  Control  (CISAC)  of the National Academy of Sciences,
       which  in  July  1997  published  a report(11) that strongly
       urges the U.S. and Russia to reduce their nuclear weapons to
       a level of 2000 total weapons, in contrast  to  the  present
       10,000 to 20,000 they now possess.  If the weapons cannot be
       dismantled  and disposed of immediately, then they should be
       demilitarized-- rendered incapable of being detonated before
       the plutonium or uranium can be removed.    And  the  excess
       weapons  should  immediately  be subject to bilateral and as
       soon as possible to international (IAEA) accounting.  It was
       not the task of the CISAC to evaluate the risk of  separated
       civil  plutonium  being  used in nuclear weaponry, but it is
       clear  that   the   CISAC   analysis   considers   separated
       reactor-grade  plutonium,  when  it  has been extracted from
       spent fuel, as representing the same  degree  of  hazard  as
       does  weapon  plutonium and that it should be subject to the
       same measures of physical protection and accountancy.

       We urge that the weapon-usable plutonium  and  high-enriched
       uranium  from dismantled weapons must be protected according
       to the "stored nuclear weapons standard" and it is important
       that the separated weapon materials be converted as soon  as
       possible  to  meet  the "spent fuel standard".   The nuclear
       weapon materials in that form are then no more attractive  a
       source of weapon-usable material than the much larger amount
       of  Pu  present  in  the unprocessed spent fuel from the 400
       power reactors in  the  world  today.    Pakistan's  nuclear
       explosions   are   an   urgent   reminder  that  the  excess
       high-enriched uranium from  dismantled  nuclear  weapons  in
       Russia and the United States is an ideal material from which
       to  make  fission  weapons,  and  that  more must be done to
       provide the conditions and resources to dilute this material
       to the status of low-enriched uranium (less than 20%  U-235)
       so that it cannot be directly used to make a fission weapon.

       An  up-to-date  and  thorough  presentation  of  the current
       status of physical protection, the implication of the stored
       weapons  standard,  and  what  steps  could  be   taken   to
       strengthen global standards, is now available on the web and
       is forthcoming in book form.(12)

       I  agree  with  Ambassador Imai(13) that Japan and the other
       non-nuclear states of the NPT should play a more active role
       in urging the U.S.  and Russia to more rapid  reductions  in
       their  nuclear weaponry and to detailed consideration of the
       elimination of nuclear weapons.  The CISAC report  considers
       elimination  (or, rather, prohibition) of nuclear weapons as
       worthy of discussion, but argues  that  until  agreement  on
       prohibition  can  be  reached,  it  is  both  practical  and
       essential to make massive reductions in all nuclear weapons.

       1   The   author  consulted  for  the  Los  Alamos  National
           Laboratory from 1950 to 1993, and  since  then  for  the
           Sandia  National Laboratories.   Most of his work at Los
           Alamos  was  involved  with  nuclear   weapons   design,
           manufacture  and  testing.    In  recent  years  he  has
           reviewed for the Department of Energy matters related to
           nuclear  weaponry   and   particularly   the   Stockpile
           Stewardship  program, primarily as a member of the JASON
           group of consultants to the U.S. Government.    Some  of
           the      JASON      reports     are     available     at
  together with other recent papers
           by the author. He is a member of the National Academy of
           Sciences, the National Academy of Engineering,  and  the
           Institute  of Medicine.   In 1997 he received the Enrico
           Fermi Award from President Clinton and the Department of
           Energy, "for a lifetime of achievement in the  field  of
           nuclear energy."  He is a member of the National Academy
           of  Sciences'  Committee  on  International Security and
           Arms Control, which  in  1994  and  1995  published  two
           reports   "The  Management  and  Disposition  of  Excess
           Weapons  Plutonium".     He  served  on   the   9-person
           Commission to Assess the Ballistic Missile Threat to the
           United  States,  established  by the U.S. Congress, that
           issued its report in July 1998.
       2   J.  Carson  Mark, "Explosive Properties of Reactor-Grade
           Plutonium," Science and  Global  Security,  4,  111-128,
           1993.    Mark headed the Theoretical Division at the Los
           Alamos National Laboratory for decades; he died in 1997.
           T-Division  played  a  major  role  in  nuclear  weapons
           design,  and  Mark was intimately involved in the design
           of both fission weapons and thermonuclear weapon.   Mark
           had  already  in  August  1990 prepared a report for the
           Nuclear Control  Institute  (  titled
           "Reactor-Grade Plutonium's Explosive Properties".
       3   "The   Management  and  Disposition  of  Excess  Weapons
           Plutonium," Committee on International Security and Arms
           Control (CISAC) of the  National  Academy  of  Sciences,
           National Academy Press, Washington, DC (1994).  The full
           text is available at
           See  pages  32-33 for discussion of nuclear weapons from
           reactor-grade plutonium.
       4   "Protection   and  Management  of  Plutonium",  American
           Nuclear Society, Special  Panel  Report  (August  1995).
           See page 25.
       5   "Final Nonproliferation and Arms Control  Assessment  of
           Weapons-Usable   Fissile  Material  Storage  And  Excess
           Plutonium Disposition Alternatives", U.S. Department  of
           Energy,  pp.  66-68,  13  January  1997.   (Available at
  as "finalnew.pdf".
       6   At a meeting of the Atomic Energy Forum/American Nuclear
       7   Plutonium, 19, 3-5, Autumn 1997.
       8   Correspondence  between  Ambassador  Imai  and myself is
           reproduced in Plutonium, 22, Summer 1998.
       9   "Management  of  Separated Plutonium", The Royal Society
           (The UK Academy of Science), London (ISBN: 0  85403  514
           1).  Summary at
       10  Sir Ronald Mason, letter to R.L. Garwin, 2 June 1998.
       11  "The Future of U.S. Nuclear Weapons Policy,"  report  of
           Committee  on  International  Security and Arms Control,
           National Academy of Sciences, Washington, D.C., National
           Academy  Press,  June   1997.      Text   available   at
       12  Full   text   at:  (click  on
           "Publications").    Matthew    Bunn,    "Security    for
           Weapons-Usable    Nuclear    Materials:        Expanding
           International Cooperation,  Strengthening  International
           Standards,"  in  Comparative  Analysis  of Approaches to
           Protection  of  Fissile  Materials:  Proceedings  of   a
           Workshop  at  Stanford  California,  July  28-30,  1997.
           Livermore, CA: Lawrence Livermore  National  Laboratory,
           Document Conf.-97-0721, 1998
       13  "Japan   Should   Initiate   Creation  of  International
           Committee to have Specific Plan for the  Elimination  of
           N-Weapons," Plutonium 21, 2-6 (Spring 1998).

WHAT JAPAN CAN DO TO HELP ITS ECONOMY AND DEPLOY ADDITIONAL NUCLEAR POWER. o Safe and affordable energy is essential to a modern, developed society, and electrical power from nuclear reactors can be both safe and affordable. Japan should continue to deploy light-water reactors as energy demand requires, with a government role in ensuring safety of operation. o The normal operation of the uranium supply and enrichment market is adequate for powering Japanese reactors for several decades. However, a particular opportunity is available to buy from Russia about 10,000 tons of low-enriched uranium that would be produced by blending excess high-enriched uranium from Russian nuclear weapons; this would be delivered as 4% U-235 and would suffice to power all existing Japanese reactors for ten years. o For the long run, fuel for all of the world's reactors could be supplied for centuries and even thousands of years by uranium from seawater-- a field in which Japan has played a leading role. Recent Japanese work (May 1998) projects a cost of $100 per kilogram of uranium from seawater, in comparison with something like $20/kg of uranium from ore. But the seawater resource in enough to operate 10,000 power reactors for 1000 years (without breeding). Even at $200/kg, uranium from seawater would be cheaper than reprocessing spent fuel and recycling plutonium and uranium. Uranium at $200/kg would increase the cost of nuclear energy by about 0.4 cents per kWh. o As of December 1996, there was in Japan about five tons of civil unirradiated plutonium, and about 15 tons of civil unirradiated Japanese plutonium in foreign countries. In addition, in spent civil reactor fuel in Japan there was almost 50 tons of plutonium. We note that ten tons of civil plutonium would suffice to make more than 1000 nuclear weapons. As with civil and military plutonium anywhere in the world, these Japanese stocks must be protected and safeguarded if they are not to contribute to the acquisition of nuclear weapons by other nations and sub-national groups. o Finally, the interests of the Japanese consumer of electrical energy and of the producer of electrical energy would be well served by the availability of a mined geologic repository, whether it is used for the vitrified fission products from the reprocessing plants at La Hague, France, or at Sellafield, Britain, or from reprocessing in Japan. Furthermore, the repository could equally well hold spent fuel in appropriate disposal casks, as is planned in the United States. It seems to me highly desirable to have competitive, commercial, mined geologic repositories in various countries of the world, with the repositories and the waste forms (including spent fuel) regulated by the International Atomic Energy Authority. Many areas of the world, as well as the nuclear energy industry itself, would benefit from the availability of such repositories, which might be built in China, in the United States, in Australia and Africa.