[DNFSB LETTERHEAD]
July l0, 2003
The Honorable Jessie Hill Roberson
Assistant Secretary for Environmental
Management
U.S. Department of Energy
1000 Independence Avenue, SW
Washington, DC 20585-0113
Dear Ms. Roberson:
Enclosed for your consideration and action,
as appropriate, are observations developed by the members of the staff of the
Defense Nuclear Facilities Safety Board (Board) concerning the electrical and
lightning protection systems for the K-Area Material Storage (KAMS) Facility,
FB-Line, and Building 235-F at the Savannah River Site. This review is part of an overall safety
assessment undertaken in response to Public Law 107-314, Section 3183, Study
of Facilities for Storage of Plutonium and Plutonium Materials at Savannah
River Site.
The staff’s review identified issues related
to electrical and lightning protection systems in each facility. Specifically, the issues concern the
capability of electrical equipment in KAMS to perform a safety function, the
adequacy of the lightning protection system and aging electrical cables in
Building 235-F, and the potential need for applying ampacity derating factors
to certain cables in FB-Line. The Board
asks to be informed of DOE’s actions to address the issues discussed in the
enclosed report.
Sincerely,
John T. Conway
Chairman
c:
Mr. Jeffrey M. Allison
Mr. Mark B. Whitaker, Jr.
Enclosure
DEFENSE
NUCLEAR FACILITIES SAFETY BOARD
June 24,
2003
MEMORANDUM FOR: J.
K. Fortenberry, Technical Director
COPIES: Board
Members
FROM: A.
K. Gwal
SUBJECT: Review
of Electrical and Lightning Protection Systems for K-Area Material Storage
Facility, FB-Line, and Building 235-F at Savannah River Site
In Public Law 107-314, Section 3183, Study
of Facilities for Storage of Plutonium and Plutonium Materials at Savannah
River Site, Congress tasked the Defense Nuclear Facilities Safety Board (Board)
to conduct a study of the adequacy of the K-Area Material Storage Facility
(KAMS) and related support facilities, such as Building 235-F (235-F), at the
Savannah River Site (SRS) for the storage of defense plutonium and defense
plutonium materials in connection with the Department of Energy’s (DOE) fissile
materials disposition program. This
report documents a review by the Board’s staff of the electrical and lightning
protection systems for KAMS, FB-Line, and Building 235-F at SRS conducted as
part of that overall study. This review
was conducted by staff members A. Gwal, B. Broderick, C. March, and T. Davis
during May 6–8, 2003.
KAMS. The Board’s staff made the
following observations with respect to KAMS.
Electrical Distribution System―In general, the staff found the electrical
distribution system to be adequate since the system is currently not credited
with any safety function.
However, in a letter dated June 12, 2003,
the Board noted that the ventilation system for KAMS was not designated as
safety-class consistent with DOE requirements to preclude unacceptable off-site
consequences during certain accidents.
Such a designation would require reclassification of the existing
electrical system and significant enhancements to the present emergency power
capability.
Electrical Calculations―The short-circuit analysis for KAMS is based
on the short-circuit currents from the original electrical calculations for
K-Reactor. Because there have been
major equipment modifications, including removal of many of the electrical
loads, the short-circuit analysis needs to be reevaluated using short-circuit
currents based on the existing configuration of the electrical distribution
system. Such an evaluation would verify
the capability of the electrical equipment to perform safely without initiating
a fire or an explosion.
Building 235-F. The
staff’s observations regarding Building 235-F are detailed below.
Lightning Protection System―The current lightning protection system is
intended to provide protection via the partial Faraday cage that is established
by the building’s interconnected structural steel rebar. However, the existing arrangement is
rendered ineffective by unbonded metallic penetrations that breach the cage
boundary. By attaching to an unbonded
rooftop or high-elevation penetration, lightning energy (capable of igniting
in-situ combustibles) could couple directly into the facility, bypassing the
rebar cage altogether. Given the lack
of viable fire suppression capabilities in 235-F, it would be prudent to
install a lightning protection system compliant with National Fire Protection
Association (NFPA) Standard 780, Standard for the Installation of Lightning
Protection System.
National Electric Code (NEC)-Type
Assessments―The
electrical distribution system in 235-F was installed in accordance with the
1957 version of the NEC. Facility
personnel were unaware of any assessments performed in recent years to ensure
compliance with either the current NEC or the code of record. Such assessments are performed routinely for
the commercial nuclear industry by NEC-qualified inspectors and have been
performed for other facilities at SRS to evaluate electrical systems for
compliance with the NEC. The staff
believes it would be beneficial to assess the existing electrical system for
235-F against current code requirements to identify potential fire hazards and
understand latent system vulnerabilities.
Calibration of Protective Devices―To ensure reliable operation, Institute of
Electrical and Electronics Engineers (IEEE) Standard 242-2001, IEEE
Recommended Practice for Protection and Coordination of Industrial and
Commercial Power Systems, recommends that electrical protective devices be
maintained and calibrated in accordance with manufacturer’s
recommendations. The 235-F circuit
breakers and relays are maintained on a 5-year calibration frequency. Representatives of 235-F could not verify
whether this calibration frequency is consistent with the manufacturer’s
recommendation. The Board’s staff
believes the calibration tests on the breakers and relays should be in
accordance with the manufacturer’s recommendation to ensure that the equipment
will operate as designed.
Electrical Cables―The majority of the electrical cables in
235-F are approximately 50 years old and have exceeded their estimated design
life. Power, instrumentation, and
control cables can deteriorate during service.
When cable jackets and insulating materials age, they become brittle and
may crack. Because a number of facility
safety systems rely on the working condition of these cables, continued
monitoring of their condition is an essential part of effective preventive
maintenance. Such monitoring of the
condition of the cables improves the service life and reliability of electrical
equipment by detecting damaged and deteriorating power and instrumentation and
control cables prior to equipment failure.
Several techniques for this type of
monitoring exist; for example, the Defense Waste Processing Facility at SRS
uses an Electronic Characterization and Diagnostics. (ECAD) system for monitoring the condition of cables. The types of degradation and problems that
can be detected by the ECAD system are changes to dielectric materials,
deterioration of circuit insulation, high-resistance connections, short
circuits, open circuits, moisture intrusion, circuit noise, and development of
conducting paths. The condition of
safety-related cables needs to be determined using a suitable system for
monitoring the condition of the cables to support a long-term storage mission
in this building.
FB-Line. The staff made the following
observations with regard to FB-Line.
Ampacity Derating of Fire-Protected Cables―In one of the stairwells, the power,
instrumentation, and control cables routed through the cable trays are coated
with a protective material (Flammastik) to prevent the initiation and rapid
propagation of fire. Such protective
coatings may reduce the heat transfer characteristics associated with the
ampacities codified in industry standards.
Hence, ampacity testing to determine whether the coating has affected
the rating of fire-protected cable systems is necessary. The Board’s staff believes IEEE Standard
848-1996, IEEE Standard Procedure for the Determination of the Ampacity
Derating of Fire-Protected Cables, should be used to evaluate the adequacy
of the coated cables in the stairwell, as well as in other locations where such
coated cables exist.
NEC-Type Assessments―As discussed above for Building 235-F, it
would be beneficial to assess the existing electrical system against current
code requirements to identify potential fire hazards and understand latent
system vulnerabilities.