[Federal Register: May 29, 1997 (Volume 62, Number 103)]
[Notices]
[Page 29118-29120]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr29my97-62]

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DEFENSE NUCLEAR FACILITIES SAFETY BOARD

[Recommendation 97-2]


Continuation of Criticality Safety at Defense Nuclear Facilities
in the Department of Energy (DOE) Complex

AGENCY: Defense Nuclear Facilities Safety Board.

ACTION: Notice; recommendation.

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SUMMARY: The Defense Nuclear Facilities Safety Board has made a
recommendation to the Secretary of Energy pursuant to 42 U.S.C. 2286a
concerning continuation of critically safety at defense nuclear
facilities in the Department of Energy (DOE) complex.

DATES: Comments, data, views, or arguments concerning this
recommendation are due on or before June 30, 1997.

ADDRESSES: Send comments, data, views, or arguments concerning this
recommendation to: Defense Nuclear Facilities Safety Board, 625 Indiana
Avenue, NW, Suite 700, Washington, DC 20004-2901.

FOR FURTHER INFORMATION CONTACT:
Kenneth M. Pusateri or Andrew L. Thibadeau at the address above or
telephone (202) 208-6400.

    Dated: May 21, 1997.
John T. Conway,
Chairman.

Continuation of Criticality Safety at Defense Nuclear Facilities in the
Department of Energy (DOE) Complex

May 19, 1997.
    In the first two or three decades following the Manhattan Project,
nearly every laboratory of the Atomic Energy Commission (AEC) had an
active program addressing some phase of the physics of neutron chain-
reacting systems. Each such study included a balance of experiment and
theoretical analysis, as in common in engineering research. Some of the
programs supported the design of nuclear weapons, some were directed at
the design of nuclear reactors, and some were conducted simply as basic
engineering research.
    As a result of these programs, expertise in neutron chain-reacting
systems was widespread; there was an abundance of individuals skilled
in achieving and controlling neutron chain reactions. These individuals
usually became expert as well in methods of avoiding a chain reaction
when this is not desired. The state of a self-sustaining chain reaction
is commonly called ``criticality.'' Guidance by these knowledgeable
individuals helped establish an admirable record of criticality safety
in the many programs the AEC conducted with fissionable material. While
occasional accidental criticality did occur at the peace of AEC
activity, it seldom caused injury to workers, and never led to
radiation affecting individuals off site. Furthermore, the last such
instance of inadvertent criticality in the United States occurred about
20 years ago.
    Some criticality research continued to replenish the supply of
these experts through the era of the Energy Research and Development
Administration (ERDA) and into the period of the Department of Energy
(DOE), though at a steadily reduced rate. Today there is almost no
theoretical research in criticality being conducted, although
university courses continue to instruct students in the theoretical
expertise that has already been developed. However, most of the early
experts in criticality safety control were drawn from experimental
research programs. For a number of years, the DOE complex placed its
reliance for criticality safety on the diminishing number of such
criticality control experts developed in earlier years. Recently,
however, DOE has been forced to supplement that group with engineers
trained on the job in the conduct of criticality calculations. The
latter group contains few individuals who have conducted critical mass
experiments. Thus collectively they have little practical experience

[[Page 29119]]

pertinent to avoiding chain reactions in nonreactor environments.
    In 1993, the Defense Nuclear Facilities Safety Board (Board) sensed
that the source of experimental competence in prevention of inadvertent
criticality was in danger of being lost entirely as a result of DOE's
impending closure of this last critical mass facility in the country.
That closure would have ended the hands-on education of new generations
of scientists and engineers in the properties and behavior of critical
systems. However, expertise in criticality safety will continue to be
needed as long as fissionable material is used and stored. The Board
viewed the end of experimental criticality studies as a threat to
criticality safety in future DOE activities, and issued Recommendations
93-2, which advised against such action. As stated in that
Recommendation,

    The Board believes it is important to maintain a good base of
information for criticality control, covering the physical
situations that will be encountered in handling and storing
fissionable material in the future, and to ensure retaining a
community of individuals competent in practicing the control.

    The Secretary accepted Recommendations 93-2 on May 12, 1993, noting
the importance of (1) improving and maintaining a criticality control
information base, especially to support future operations in handling,
processing, and storage or disposal of fissionable material; (2)
retaining a cadre of individuals competent in practicing criticality
control and safety; (3) continuing an experimental program; (4)
continuing an education program for criticality safety professionals;
(5) coordinating the criticality program among various users; (6)
performing a criticality assessment with respect to defense nuclear
facilities to determine the scope of current and future requirements
for criticality experiments, predictability, and training, and (7)
investigating the mission requirements, program funding, and landlord
issues.
    Since Recommendation 93-2 was issued, DOE has made substantial
progress in coordination and implementation of the criticality
experiments program. Funding for the program has stabilized, albeit at
a low level, and work has been initiated on a prioritized list of
experiments. However, a basic set of problems continues to exist
throughout the DOE complex with regard to criticality control. Among
the problems are the following:
    1. In the past, it was found that only a few experienced
criticality engineers were needed to guide criticality safety at even
the most complex facilities. However, at the majority of DOE facilities
where accidental criticality is currently a potential issue, the number
of engineers assigned to criticality control is surprisingly large. The
Typical criticality safety staff consists mainly of individuals who
have no prior first-hand experience in criticality, and who have been
trained on the job in analytical aspects of criticality control after
being hire. They lack background in neutron physics on a fundamental
level, and are not familiar with work on assemblies near the critical
state, activities that would foster intuitive approaches to criticality
control. Therefore, when faced with the need to determine what must be
done to avoid a chain reaction, they most frequently fall back on
complex multidimensional Monte Carlo calculations. Their use of
simplified methods and their reliance on published data are minimal.
The Board points out that complex analysis may be needed for some
cases, such as those with difficult geometry, but such analysis is
time-consuming and may dramatically slow preparation for the activities
being evaluated.
    2. Operational practices at some DOE facilities place criticality
control in a central position in operations, with the criticality
engineer establishing certain aspects of operation for safety reasons.
Effectively, the criticality engineer, with all the shortcomings
described in 1 above, becomes the critical path for line management.
This causes delays in the ability of the line management to develop
overall safety requirements.
    3. In the past, most of the criticality safety data in guidance
documents has been directed to activities involving production of
nuclear weapons. The guidance has incorporated data from several
experimental programs established to ensure avoidance of unintentional
criticality in weapons programs. The experimental data has often been
generalized by analysis of the experimental results and by theory
benchmarked against experiments. The missions of DOE have changed
substantially, however, and guidance for other types of activities is
not needed. It is particularly important that guidance be developed to
help in analyzing the safety of cleanup operations and the handling,
storage, and shipping of miscellaneous containers that include
fissionable material mixed with other material.
    The above problems have had a significant effect on the
productivity of several DOE operations. They have adversely affected
safety by extending the period of time required for meeting safety
commitments, such as those responding to Board Recommendation 94-1. In
so doing, they have absorbed resources potentially needed for other
safety-related activities at DOE's defense nuclear facilities. In this
light, the Board believes action should be taken to eliminate these
problems and to ensure that criticality safety can continue to be
achieved efficiently in DOE's future operations.
    Therefore the Board recommends that DOE:
    1. Restructure the program of experimental research in criticality
established under the Implementation Plan for Recommendation 93-2 to
emphasize determination of bounding values for criticality of systems
most important in the current programs at DOE facilities.
    2. Organize the records of calculations and experiments conducted
to ensure the criticality safety of DOE's past operations so as to
provide guidance for criticality safety in similar situations in the
future and avoid repetition of past problems.
    3. Establish a program to interpolate and extrapolate such existing
calculations and data as a function of physical circumstances that may
be encountered in the future, so that useful guidance and bounding
curves will result.
    4. Collect and issue the experimental and theoretical data from the
above in a publications as guidance for future activities.
    5. Clarify in guidance that simple, bounding methods of analysis
can be used in place of specific theoretical analysis in setting
criticality limits for processes, and that limits derived in this
manner are even preferable where they serve the purpose. The decreasing
order of preference should be experimental data, theory benchmarked
against experimental data, and nonbenchmarked criticality analysis with
an adequate safety margin.
    6. Develop and institute a short but intensive course of
instruction in criticality and criticality safety at DOE's criticality
experiments facility to serve as the foundation for a program of formal
qualification of criticality engineers. This course should instill in
students a familiarity with the factors contributing to criticality,
the physical behavior of systems at and near criticality, and a
theoretical understanding of neutron multiplication processes in
critical and subcritical systems. A goal would be for reliance for
criticality safety at any DOE facilities to rest in a group of
individuals endowed with such experience.
    7. Where not already done, assign criticality safety as a staff
function

[[Page 29120]]

assisting line management, with safety responsibility residing in line
management.
    8. Identify a core group of criticality experts experienced in the
theoretical experimental aspects of neutron chain reactions to advise
on the above steps and assist in resolving future technical issues.
    9. Organize funding of the criticality research and instruction
program to improve its stability and to recognize the cross-cutting
importance of this activity.
John T. Conway,
Chairman.
[FR Doc. 97-13977 Filed 5-28-97; 8:45 am]
BILLING CODE 3670-01-M
