[DNFSB
LETTERHEAD]
The Honorable Linton Brooks
Administrator
National Nuclear Security Administration
Dear Ambassador Brooks:
The staff of the Defense Nuclear Facilities
Safety Board (Board) recently reviewed the Operational Safety Requirements for
Enriched Uranium Operations (EUO) at the Y-12 National Security Complex. The Board is pleased to note that, for the
most part, those systems, structures, and components in Building 9212 reviewed
by the staff should be able to prevent or mitigate the hazard for which they
are credited. However, the Board’s staff
has identified some issues that could potentially compromise the ability of EUO
to operate safely.
During the staffs review, discussions of
fire suppression within EUO revealed that the six credited sprinkler systems
within Building 9212 had been designed to National Fire Protection Association
(NFPA) 13, Standard for the Installation
of Sprinkler Systems, a code that dates back to 1969. Since that time, the code has been revised to
incorporate new knowledge of the piping sizes required to maintain adequate
fluid flow to all parts of the sprinkler system. This failure to capture changes in the NFPA
code means that parts of EUO may have inadequate fire suppression coverage.
Furthermore, one of the six credited
sprinkler systems was recently upgraded in safety functional classification
from safety-significant to safety-class without an evaluation to ensure a level
of effectiveness and reliability commensurate with its new safety designation. BWXT Y-12 personnel acknowledged that no
analysis had been performed to ensure that these sprinkler systems can operate
effectively despite their substantially outdated code of record. The Board believes that the adequacy of the
subject sprinkler systems to meet current standards should be evaluated.
Additional issues are identified in the
enclosed report, which is provided for your use as appropriate. The Board will continue to follow closely the
progress made by the Y-12 National Security Complex in addressing these issues.
Sincerely,
John T. Conway
Chairman
c: The
Honorable Everet H. Beckner
Mr. William J. Brumley
Mr. David E. Beck
Mr. Mark B. Whitaker, Jr.
Enclosure
DEFENSE NUCLEAR FACILITIES SAFETY BOARD
Staff Issue Report
MEMORANDUM
FOR: J. K. Fortenberry, Technical Director
COPIES: Board
Members
FROM: R.
Rauch
SUBJECT: Y-12
Building 92 12 Operational Safety Requirements
This report documents a review by the staff
of the Defense Nuclear Facilities Safety Board (Board) of the Operational
Safety Requirements (OSRs) for Building 9212 Enriched Uranium Operations (EUO)
at the Y-12 National Security Complex (Y-12). Staff members R. Rauch, W. Andrews, C. March,
and M. Piccarreta and outside expert R. West conducted this review.
Background. Efforts to restart EUO began in 1996 using a
phased sequence. Casting, rolling,
forming, and machining operations were restarted in 1998, and reduction
operations followed in April 2001. Preparations for wet chemistry restart were
completed in March 2003. The last major
restart effort for EUO is the oxide conversion process, scheduled for
completion in calendar year 2004. The
Building 9212 Basis for Interim Operation (BIO) and OSRs were developed and
implemented as part of the restart effort following the shutdown of EUO in 1994.
The BIO has not been approved as a Title
10 Code of Federal Regulations (CFR) Part 830 compliant documented safety analysis
(DSA). An exception has been granted to
defer submission of this DSA until September 2004.
Findings. The
purpose of the staffs review was to assess the effectiveness and reliability of
selected Building 9212 OSRs. Sixteen
structures, systems, and components were analyzed in the areas of procurement,
design, maintenance, operations, and testing requirements. The OSRs that have been credited for the oxide
conversion process were specifically excluded from the scope of the review
because the restart efforts for this system have not been completed. The controls chosen for evaluation included
ventilation, fire suppression, water detection, phase separation, and alarm
systems. These controls are credited to
prevent or mitigate a variety of accident types, such as criticality, loss of
confinement, fire, and explosion scenarios.
The Board’s staff concluded that most
controls could perform effectively and reliably. However, the staff identified issues in the
following areas.
Adequacy
of Safety System Design―Building 9212 contains five safety-significant sprinkler systems and one
sprinkler system that was recently upgraded to a safety-class functional
classification. The code of record for
these systems, National Fire Protection Association (NFPA) 13, Standard for the Installation of Sprinkler
Systems, dates back to 1969. Given
the substantial changes in NFPA 13 requirements since that time―particularly with respect to pipe sizing
requirements, which affect fluid flow rates―the Board’s staff believes that portions of
the credited sprinkler system piping scheme for Building 9212 may have
insufficient fluid flow. Inadequate fire
protection for parts of EUO could result in high-consequence events with
significant radiological and toxicological off-site consequences exceeding
evaluation guidelines.
BWXT Y-12 personnel acknowledged that no
evaluation of the design adequacy of these systems had been conducted to ensure
that the credited sprinkler systems in Building 9212 can perform to the
expectations of effectiveness set forth in the current form of consensus
industry standards such as NFPA 13. Without such an evaluation―particularly in the case of the upgraded
sprinkler system, for which there are particularly high expectations of both effectiveness
and reliability―site
workers and the public stand at an increased risk of an event with potentially
significant consequences. Other sites in
the defense nuclear complex have recognized the benefit of developing a process
for review of design adequacy for situations such as this in which a given
safety system has undergone an upgrade in safety classification and/or has a
substantially outdated code of record. The Board’s staff believes that the
development of such a review process at Y-12 could improve safe operation at
the site by ensuring that credited safety controls can perform at a level of
effectiveness commensurate with their functional classification.
Organic
Phase Separators―The
Building 9212 BIO credits seven organic phase separators as a design feature
for safety in preventing an explosive event due to a reaction between organic
and acid process streams. Four
separators are designed to automatically decant organic process streams for
expected and off-normal operational flow rates. Three separators (the pour-up separator,
high-capacity evaporator separator, and wiped-film evaporator separator),
however, require operator action (e.g., administrative controls) to ensure safe
operation. Despite the Department of
Energy’s (DOE) preference for engineered controls, it appears that these
administrative controls will remain in place even after planned modifications to
two of these three separators have been completed. Furthermore, these administrative controls should
be implemented consistent with DOE’s Implementation Plan for Recommendation 2002-3,
Requirements for the Design,
Implementation, and Maintenance of Administrative Controls.
BWXT Y-12 personnel stated to the Board’s staff
that there are no physical limitations preventing these three separators from
being modified to decant automatically; however, significant redesign and/or
equipment relocation would be required. Based on applicable accident analyses and
controls, BWXT Y-12 personnel believe that the current phase separator configurations
address the postulated events at an acceptable level of risk.
Given DOE’s stated preference for engineered
over administrative controls, a formal review of this issue with basis for
conclusion may be warranted. If the
decision is made to retain administrative controls for these separators, it
would be advisable to conduct a formal analysis that documents this decision
(including the required modifications, the reasons for not implementing them,
and the associated risk).
Conclusion. The
Board’s staff found that most preventive and mitigative controls adequately
protect against the hazard for which they are credited. The staff identified some issues, however,
that demonstrate potential weaknesses in the Building 9212 OSRs. In particular, it appears that no formal
process exists to ensure that a given control operates at the level of
reliability and effectiveness associated with its classification.