[Federal Register: December 15, 2004 (Volume 69, Number 240)]
[Notices]
[Page 75047-75049]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr15de04-45]
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DEFENSE NUCLEAR FACILITIES SAFETY BOARD
[Recommendation 2004-2]
Active Confinement Systems
AGENCY: Defense Nuclear Facilities Safety Board.
ACTION: Notice, recommendation.
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SUMMARY: The Defense Nuclear Facilities Safety Board has unanimously
approved Recommendation 2004-2, for DOE to consider. Recommendation
2004-2 deals with the confinement of hazardous materials at defense
nuclear facilities in the Department of Energy complex.
DATES: Comments, data, views, or arguments concerning the
recommendation are due on or before January 14, 2005.
ADDRESSES: Send comments, data, views, or arguments concerning this
recommendation to: Defense Nuclear
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Facilities Safety Board, 625 Indiana Avenue, NW., Suite 700,
Washington, DC 20004-2001.
FOR FURTHER INFORMATION CONTACT: Kenneth M. Pusateri or Andrew L.
Thibadeau at the address above or telephone (202) 694-7000.
Dated: December 10, 2004.
A.J. Eggenberger,
Vice Chairman.
Recommendation 2004-2 to the Secretary of Energy, Pursuant to 42 U.S.C.
2286a(a)(5), Atomic Energy Act of 1954, As Amended
Dated: December 7, 2004.
There is a long-standing safety practice in the design,
construction, and operation of nuclear facilities to build-in and
maintain structures, systems, and components that contain or confine
radioactive materials. The Department of Energy (DOE) establishes
requirements to ensure such containment or confinement. In the
hierarchy of safety controls, passive design features are preferred
over active systems; however, controls must be capable of performing
their intended function. Passive confinement systems are not
necessarily capable of containing hazardous materials with
confidence because they allow a quantity of unfiltered air
contaminated with radioactive material to be released from an
operating nuclear facility following certain accident scenarios.
Safety related active confinement ventilation systems will continue
to function during an accident, thereby ensuring that radioactive
material is captured by filters before it can be released into the
environment.
The enclosed technical report, DNFSB/TECH-34, Confinement of
Radioactive Materials at Defense Nuclear Facilities, compares the
benefits of including a safety-related active confinement
ventilation system to those of relying only on a passive confinement
system. This technical report illustrates that using only a passive
confinement system for an existing or new defense nuclear processing
facility would not account for many safety considerations such as
post-accident monitoring and response, and may result in the release
of an undeterminable amount of radioactive materials, the
consequences of which could approach that of the unmitigated
scenarios.
The Defense Nuclear Facilities Safety Board (Board) has advised
DOE in various ways during the past decade regarding the need to pay
increased attention to the design and operational reliability of the
confinement ventilation systems at defense nuclear facilities. These
Board efforts include transmittal of a technical report on May 31,
1995, Overview of Ventilation Systems at Selected DOE Plutonium
Processing and Handling Facilities, a letter to the Deputy Secretary
of Energy dated July 8, 1999, and Recommendation 2000-2,
Configuration Management, Vital Safety Systems, on March 8, 2000.
This advice has helped DOE improve the reliability of its
confinement ventilation systems. However, DOE requirements have
become less prescriptive during the last decade as DOE Order
6430.1A, General Design Criteria Manual, was replaced with DOE Order
420.1, Facility Safety, and its subsequent revisions. Furthermore,
it has become apparent that the Board's advice on confinement
systems is not being rigorously pursued as evidenced by the
following:
On December 27, 2002, the Board sent a letter to the
National Nuclear Security Administration (NNSA) regarding the
confinement concept used for the Highly Enriched Uranium Materials
Facility at the Y-12 National Security Complex. The proposed
confinement concept was based on isolating the radioactive material
in the building using a passive confinement system under certain
abnormal events. The Board communicated safety concerns associated
with this concept in the letter; subsequently, the confinement
concept for HEUMF was modified to adopt a safety-related active
ventilation system.
On April 12, 2004, the Board sent a letter to the
Administrator of NNSA regarding similar safety issues related to the
confinement systems for the plutonium facility at the Lawrence
Livermore National Laboratory. The proposed approach utilized
passive confinement of radioactive material from the facility during
certain accident scenarios. Further, because the offsite dose
consequences of such an unfiltered release were calculated to be
below DOE's evaluation guideline (25 rem), the proposal included
downgrading the existing safety-class active confinement ventilation
system to a safety-significant system. The Board believed that the
new approach was inconsistent with a defense-in-depth philosophy.
Subsequently, the Livermore Site Office commissioned an independent
calculation of the amount of the unfiltered release. These
calculations yielded results that were an order of magnitude greater
than the original building leakage estimates--clearly indicating
that significant uncertainties existed in the analytical techniques.
As a result, NNSA decided to maintain the existing safety-class
active confinement ventilation system.
On August 27, 2004, the Board sent a letter to the
Under Secretary of Energy regarding the confinement approach
proposed for the Salt Waste Processing Facility at the Savannah
River Site. The confinement concept for this new facility is based
on isolation of the process building using passive confinement
during accident scenarios. The Board suggested that the salt waste
facility should be designed with a safety-related active ventilation
system.
A number of existing facilities (including the TA-55 Plutonium
Facility, the Device Assembly Facility, and the Hanford Evaporator)
rely on passive or non-safety related confinement systems. More
importantly, designs for proposed facilities (including Chemistry
and Metallurgy Research Replacement Facility and the Salt Waste
Processing Facility) are based on the same passive confinement
concept and use an assumed quantitative value for the building leak
path factor as a design criterion.
These examples illustrate two primary concerns. First, a
reliance on calculations that do not appropriately account for large
uncertainties is not defensible. These analytically determined
building leak path factors are based on a combination of several
computer programs that were not specifically designed for this
purpose. Furthermore, it is generally impossible for these programs
to model the true conditions of a real accident because of the
uncertain behavior of the workers and emergency crews responding to
the event.
Second, these examples represent a fundamental change in DOE's
approach to protection of the public near defense nuclear
facilities. DOE appears to be using the evaluation guideline of 25
rem exposure at the site boundary as a design criterion and an
allowable dose to the public. This is contrary to the Board's July
8, 1999 letter to the Deputy Secretary of Energy that states ``the
25 rem evaluation guideline is not to be treated as a design
acceptance criterion nor as a justification for nullifying the
general design criteria relative to defense-in-depth safety
measures.'' It is also contrary to DOE-STD-3009 that states that the
25 rem evaluation guideline ``is not to be treated as a design
acceptance criterion.'' However, the Board continues to see 25 rem
at the site boundary used as an acceptance criterion for the
performance of confinement systems. The Board is concerned that in
these examples DOE and its contractors are underestimating the
significance of the performance requirements for a confinement
ventilation system and are relying on questionable calculations of
offsite doses to evaluate performance. The Board reiterates that the
25 rem evaluation guideline is solely to be used for guidance for
the classification of safety controls, and not as an acceptable dose
to the public for the purpose of designing or operating defense
nuclear facilities.
Notwithstanding the concerns discussed above, DOE continues to
pursue a passive confinement approach in the design of some new
nuclear facilities that have the potential for a radiological
release. The Board recognizes that DOE's defense nuclear complex is
comprised of a wide variety of nuclear facilities with an equally
diverse range of materials, forms, activities, and proximities to
the public. For this reason, it is difficult to prescribe a single,
broadly-applicable design requirement. However, in light of the
examples discussed above, the Board believes a more prescriptive
design requirement is needed.
The Board further recognizes that certain Hazard Category 2 and
3 defense nuclear facilities may not benefit significantly from an
active confinement ventilation system. An example would be a
facility that stores radioactive material in protected, safety-class
containers. Other examples may be certain tritium facilities,
outside storage locations, burial grounds, or facilities with
planned declining nuclear material inventories and scheduled for
decommissioning in the near future. This recommendation is not meant
to require an active confinement ventilation system in all such
cases.
Therefore, the Board recommends that DOE:
1. Disallow reliance on passive confinement systems and require
an active confinement ventilation system for all new and existing
Hazard Category 2 defense nuclear facilities with the potential for
a
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radiological release. These systems are expected to be classified as
safety-class or safety-significant as required by a conservative
application of DOE-approved methodology, and should be designed and
maintained to function during abnormal and accident conditions.
Exceptions to such classifications should be approved at a level in
DOE that ensures a consistent, conservative approach throughout the
complex.
2. Disallow reliance on passive confinement systems and require
an active confinement ventilation system for all new and existing
Hazard Category 3 defense nuclear facilities with the potential for
a radiological release. These systems would not ordinarily be
classified as safety-class or safety-significant unless such
designation is required by the DOE-approved methodology.
3. Revise all applicable DOE directives pertaining to operation
of existing facilities, design and construction of new facilities,
and major modifications to existing facilities, in accordance with
Items 1 and 2 above. These revisions should include guidance for
determining when a facility would not benefit from an active
confinement ventilation system.
4. Assess existing facilities, ongoing major modifications, and
new design/construction projects, to ensure that:
(a) The confinement strategy described above is implemented, and
(b) The 25 rem evaluation guideline is used solely for
classification of safety controls.
Section 42 U.S.C. 2286d(e) provides authority to the Secretary
of Energy to ``implement any such Recommendation (or part of any
such Recommendation) before, on, or after the date on which the
Secretary of Energy transmits the implementation plan to the Board
under this subsection.'' The Board suggests that the Secretary of
Energy consider taking action on Item 4 above in parallel with the
development of an Implementation Plan for this Recommendation.
In addition, the Board's Recommendation 2004-1, Oversight of
Complex, High-Hazard Nuclear Operations, addresses the need for
complex-wide consistency in the application of DOE requirements and
expectations. The Board expects the mechanisms established in
response to Recommendation 2004-1 would likewise ensure consistent,
conservative implementation of the confinement requirement provided
here.
John T. Conway,
Chairman.
[FR Doc. 04-27426 Filed 12-14-04; 8:45 am]
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