United Nations

A/RES/47/68


General Assembly

Distr. GENERAL  

14 December 1992

ORIGINAL:
ENGLISH



                                                   A/RES/47/68
                                                   85th plenary meeting
                                                   14 December 1992
 
 
     47/68.  Principles Relevant to the Use of Nuclear Power Sources
             in Outer Space
 
     The General Assembly,
 
     Having considered the report of the Committee on the Peaceful Uses of
Outer Space on the work of its thirty-fifth session and the text of the
Principles Relevant to the Use of Nuclear Power Sources in Outer Space as
approved by the Committee and annexed to its report,
 
     Recognizing that for some missions in outer space nuclear power sources
are particularly suited or even essential owing to their compactness, long
life and other attributes,
 
     Recognizing also that the use of nuclear power sources in outer space
should focus on those applications which take advantage of the particular
properties of nuclear power sources,
 
     Recognizing further that the use of nuclear power sources in outer space
should be based on a thorough safety assessment, including probabilistic risk
analysis, with particular emphasis on reducing the risk of accidental exposure
of the public to harmful radiation or radioactive material,
 
     Recognizing the need, in this respect, for a set of principles containing
goals and guidelines to ensure the safe use of nuclear power sources in outer
space,
 
     Affirming that this set of Principles applies to nuclear power sources in
outer space devoted to the generation of electric power on board space objects
for non-propulsive purposes, which have characteristics generally comparable
to those of systems used and missions performed at the time of the adoption of
the Principles,
 
     Recognizing that this set of Principles will require future revision in
view of emerging nuclear power applications and of evolving international
recommendations on radiological protection,
 
     Adopts the Principles Relevant to the Use of Nuclear Power Sources in
Outer Space as set forth below.
 
             Principle 1.  Applicability of international law
 
     Activities involving the use of nuclear power sources in outer space
shall be carried out in accordance with international law, including in
particular the Charter of the United Nations and the Treaty on Principles
Governing the Activities of States in the Exploration and Use of Outer Space,
including the Moon and Other Celestial Bodies.
 
                   Principle 2.  Use of terms
 
1.   For the purpose of these Principles, the terms "launching State" and
"State launching" mean the State which exercises jurisdiction and control over
a space object with nuclear power sources on board at a given point in time
relevant to the principle concerned.
 
2.   For the purpose of principle 9, the definition of the term "launching
State" as contained in that principle is applicable.
 
3.   For the purposes of principle 3, the terms "foreseeable" and "all
possible" describe a class of events or circumstances whose overall
probability of occurrence is such that it is considered to encompass only
credible possibilities for purposes of safety analysis.  The term "general
concept of defence-in-depth" when applied to nuclear power sources in outer
space refers to the use of design features and mission operations in place of
or in addition to active systems, to prevent or mitigate the consequences of
system malfunctions.  Redundant safety systems are not necessarily required
for each individual component to achieve this purpose.  Given the special
requirements of space use and of varied missions, no particular set of systems
or features can be specified as essential to achieve this objective.  For the
purposes of paragraph 2 (d) of principle 3, the term "made critical" does not
include actions such as zero-power testing which are fundamental to ensuring
system safety.
 
             Principle 3.  Guidelines and criteria for safe use
 
     In order to minimize the quantity of radioactive material in space and
the risks involved, the use of nuclear power sources in outer space shall be
restricted to those space missions which cannot be operated by non-nuclear
energy sources in a reasonable way.
 
1.   General goals for radiation protection and nuclear safety
 
     (a)  States launching space objects with nuclear power sources on board
shall endeavour to protect individuals, populations and the biosphere against
radiological hazards.  The design and use of space objects with nuclear power
sources on board shall ensure, with a high degree of confidence, that the
hazards, in foreseeable operational or accidental circumstances, are kept
below acceptable levels as defined in paragraphs 1 (b) and (c).
 
     Such design and use shall also ensure with high reliability that
radioactive material does not cause a significant contamination of outer
space.
 
     (b)  During the normal operation of space objects with nuclear power
sources on board, including re-entry from the sufficiently high orbit as
defined in paragraph 2 (b), the appropriate radiation protection objective for
the public recommended by the International Commission on Radiological
Protection shall be observed.  During such normal operation there shall be no
significant radiation exposure.
 
     (c)  To limit exposure in accidents, the design and construction of the
nuclear power source systems shall take into account relevant and generally
accepted international radiological protection guidelines.
 
     Except in cases of low-probability accidents with potentially serious
radiological consequences, the design for the nuclear power source systems
shall, with a high degree of confidence, restrict radiation exposure to a
limited geographical region and to individuals to the principal limit of 1 mSv
in a year.  It is permissible to use a subsidiary dose limit of 5 mSv in a
year for some years, provided that the average annual effective dose
equivalent over a lifetime does not exceed the principal limit of 1 mSv in a
year.
 
     The probability of accidents with potentially serious radiological
consequences referred to above shall be kept extremely small by virtue of the
design of the system.
 
     Future modifications of the guidelines referred to in this paragraph
shall be applied as soon as practicable.
 
     (d)  Systems important for safety shall be designed, constructed and
operated in accordance with the general concept of defence-in-depth.  Pursuant
to this concept, foreseeable safety-related failures or malfunctions must be
capable of being corrected or counteracted by an action or a procedure,
possibly automatic.
 
     The reliability of systems important for safety shall be ensured, inter
alia, by redundancy, physical separation, functional isolation and adequate
independence of their components.
 
     Other measures shall also be taken to raise the level of safety.
 
2.   Nuclear reactors
 
     (a)  Nuclear reactors may be operated:
 
     (i)  On interplanetary missions;
 
     (ii) In sufficiently high orbits as defined in paragraph 2 (b);
 
    (iii) In low-Earth orbits if they are stored in sufficiently high orbits
          after the operational part of their mission.
 
     (b)  The sufficiently high orbit is one in which the orbital lifetime is
long enough to allow for a sufficient decay of the fission products to
approximately the activity of the actinides.  The sufficiently high orbit must
be such that the risks to existing and future outer space missions and of
collision with other space objects are kept to a minimum.  The necessity for
the parts of a destroyed reactor also to attain the required decay time before
re-entering the Earth's atmosphere shall be considered in determining the
sufficiently high orbit altitude.
 
     (c)  Nuclear reactors shall use only highly enriched uranium 235 as fuel.
The design shall take into account the radioactive decay of the fission and
activation products.
 
     (d)  Nuclear reactors shall not be made critical before they have reached
their operating orbit or interplanetary trajectory.
 
     (e)  The design and construction of the nuclear reactor shall ensure that
it can not become critical before reaching the operating orbit during all
possible events, including rocket explosion, re-entry, impact on ground or
water, submersion in water or water intruding into the core.
 
     (f)  In order to reduce significantly the possibility of failures in
satellites with nuclear reactors on board during operations in an orbit with a
lifetime less than in the sufficiently high orbit (including operations for
transfer into the sufficiently high orbit), there shall be a highly reliable
operational system to ensure an effective and controlled disposal of the
reactor. 
 
3.   Radioisotope generators
 
     (a)  Radioisotope generators may be used for interplanetary missions and
other missions leaving the gravity field of the Earth.  They may also be used
in Earth orbit if, after conclusion of the operational part of their mission,
they are stored in a high orbit.  In any case ultimate disposal is necessary.
 
     (b)  Radioisotope generators shall be protected by a containment system
that is designed and constructed to withstand the heat and aerodynamic forces
of re-entry in the upper atmosphere under foreseeable orbital conditions,
including highly elliptical or hyperbolic orbits where relevant.  Upon impact,
the containment system and the physical form of the isotope shall ensure that
no radioactive material is scattered into the environment so that the impact
area can be completely cleared of radioactivity by a recovery operation.
 
                 Principle 4.  Safety assessment
 
1.   A launching State as defined in principle 2, paragraph 1, at the time of
launch shall, prior to the launch, through cooperative arrangements, where
relevant, with those which have designed, constructed or manufactured the
nuclear power source, or will operate the space object, or from whose
territory or facility such an object will be launched, ensure that a thorough
and comprehensive safety assessment is conducted.  This assessment shall cover
as well all relevant phases of the mission and shall deal with all systems
involved, including the means of launching, the space platform, the nuclear
power source and its equipment and the means of control and communication
between ground and space.
 
2.   This assessment shall respect the guidelines and criteria for safe use
contained in principle 3.
 
3.   Pursuant to article XI of the Treaty on Principles Governing the
Activities of States in the Exploration and Use of Outer Space, including the
Moon and Other Celestial Bodies, the results of this safety assessment,
together with, to the extent feasible, an indication of the approximate
intended time-frame of the launch, shall be made publicly available prior to
each launch, and the Secretary-General of the United Nations shall be informed
on how States may obtain such results of the safety assessment as soon as
possible prior to each launch.
 
             Principle 5.  Notification of re-entry
 
1.   Any State launching a space object with nuclear power sources on board
shall in a timely fashion inform States concerned in the event this space
object is malfunctioning with a risk of re-entry of radioactive materials to
the Earth.  The information shall be in accordance with the following format:
 
     (a)  System parameters:
 
     (i)  Name of launching State or States, including the address of the
          authority which may be contacted for additional information or
          assistance in case of accident;
 
     (ii) International designation;
 
    (iii) Date and territory or location of launch;
 
     (iv) Information required for best prediction of orbit lifetime,
          trajectory and impact region;
 
     (v)  General function of spacecraft;
 
     (b)  Information on the radiological risk of nuclear power source(s):
 
     (i)  Type of nuclear power source:  radioisotopic/reactor;
 
     (ii) The probable physical form, amount and general radiological
          characteristics of the fuel and contaminated and/or activated
          components likely to reach the ground.  The term "fuel" refers to
          the nuclear material used as the source of heat or power.
 
 
This information shall also be transmitted to the Secretary-General of the
United Nations.
 
2.   The information, in accordance with the format above, shall be provided
by the launching State as soon as the malfunction has become known.  It shall
be updated as frequently as practicable and the frequency of dissemination of
the updated information shall increase as the anticipated time of re-entry
into the dense layers of the Earth's atmosphere approaches so that the
international community will be informed of the situation and will have
sufficient time to plan for any national response activities deemed necessary.
 
3.   The updated information shall also be transmitted to the
Secretary-General of the United Nations with the same frequency.
 
                   Principle 6.  Consultations
 
     States providing information in accordance with principle 5 shall, as far
as reasonably practicable, respond promptly to requests for further
information or consultations sought by other States.
 
               Principle 7.  Assistance to States
 
1.   Upon the notification of an expected re-entry into the Earth's atmosphere
of a space object containing a nuclear power source on board and its
components, all States possessing space monitoring and tracking facilities, in
the spirit of international cooperation, shall communicate the relevant
information that they may have available on the malfunctioning space object
with a nuclear power source on board to the Secretary-General of the United
Nations and the State concerned as promptly as possible to allow States that
might be affected to assess the situation and take any precautionary measures
deemed necessary.
 
2.   After re-entry into the Earth's atmosphere of a space object containing a
nuclear power source on board and its components:
 
     (a)  The launching State shall promptly offer and, if requested by the
affected State, provide promptly the necessary assistance to eliminate actual
and possible harmful effects, including assistance to identify the location of
the area of impact of the nuclear power source on the Earth's surface, to
detect the re-entered material and to carry out retrieval or clean-up
operations;
 
     (b)  All States, other than the launching State, with relevant technical
capabilities and international organizations with such technical capabilities
shall, to the extent possible, provide necessary assistance upon request by an
affected State.
 
In providing the assistance in accordance with subparagraphs (a) and (b)
above, the special needs of developing countries shall be taken into account.
 
                  Principle 8.  Responsibility
 
     In accordance with article VI of the Treaty on Principles Governing the
Activities of States in the Exploration and Use of Outer Space, including the
Moon and Other Celestial Bodies, States shall bear international
responsibility for national activities involving the use of nuclear power
sources in outer space, whether such activities are carried on by governmental
agencies or by non-governmental entities, and for assuring that such national
activities are carried out in conformity with that Treaty and the
recommendations contained in these Principles.  When activities in outer space
involving the use of nuclear power sources are carried on by an international
organization, responsibility for compliance with the aforesaid Treaty and the
recommendations contained in these Principles shall be borne both by the
international organization and by the States participating in it.
 
            Principle 9.  Liability and compensation
 
1.   In accordance with article VII of the Treaty on Principles Governing the
Activities of States in the Exploration and Use of Outer Space, including the
Moon and Other Celestial Bodies, and the provisions of the Convention on
International Liability for Damage Caused by Space Objects, each State which
launches or procures the launching of a space object and each State from whose
territory or facility a space object is launched shall be internationally
liable for damage caused by such space objects or their component parts.  This
fully applies to the case of such a space object carrying a nuclear power
source on board.  Whenever two or more States jointly launch such a space
object, they shall be jointly and severally liable for any damage caused, in
accordance with article V of the above-mentioned Convention.
 
2.   The compensation that such States shall be liable to pay under the
aforesaid Convention for damage shall be determined in accordance with
international law and the principles of justice and equity, in order to
provide such reparation in respect of the damage as will restore the person,
natural or juridical, State or international organization on whose behalf a
claim is presented to the condition which would have existed if the damage had
not occurred.
 
3.   For the purposes of this principle, compensation shall include
reimbursement of the duly substantiated expenses for search, recovery and
clean-up operations, including expenses for assistance received from third
parties. 
 
              Principle 10.  Settlement of disputes
 
     Any dispute resulting from the application of these Principles shall be
resolved through negotiations or other established procedures for the peaceful
settlement of disputes, in accordance with the Charter of the United Nations.
 
               Principle 11.  Review and revision
 
     These Principles shall be reopened for revision by the Committee on the
Peaceful Uses of Outer Space no later than two years after their adoption.