Fire Hazards Analysis - SLAC National Accelerator Laboratory

Fire Hazards Analysis - SLAC National Accelerator Laboratory
BaBar
Fire Hazards Analysis
Executive Summary
Executive Summary
Fire Hazards Analysis
for the
BaBar Detector Project
Prepared for
Stanford Linear Accelerator Laboratory
Stanford, CA 94309-4349
Prepared by
Hughes Associates, Inc.
3610 Commerce Drive, Suite 817
Baltimore, MD 2 1227- 1652
FAX 410-737-8688
410-737-8677
November 26, 1996
Fire Hazards Analysis for the BaBar Detector Project
Executive Summary
Contents
Page
ES-1.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
ES-2.0 BaBar Facility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ES2.1 ConstructiodOccupancy Classification . . . . . . . . . . . . . . . . . . . . . . . . . .
ES2.2 BaBar Equipment/Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ES2.3 BaBar Support SystemsEquiprnent . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electronics House . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main Control Center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cryogenics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Mixing House/Gas Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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ES-3.0 Fire Hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ES3.1 BaBar Fire Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ES3.2 Candidate Exposure Fire Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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ES-4.0 Fire Protection Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ES4.1 Existing Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ES4.2 Planned Modifications/Additions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main IR-2 Hall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electronics House . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Counting House (Building 621) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cryogenics Control/PEP Magnet Power Supplies(Bui1ding 624) . . . . . . .
Tool Shed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PEP-I1 Power/BaBar Solenoid Power Building (Building 625) . . . . . . . .
Gas Mixing House . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BaBar Fire Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical/Signaling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electronics Support Racks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cable Tunnel Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BaBar Exposure Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ES-5.0 Property and Equipment Criticality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ES5.1 Safety Class Equipment/Vital Safety Systems . . . . . . . . . . . . . . . . . . . .
ES5.2 High Value Property . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ES5.3 Critical Process Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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CONTENTS (Concluded)
ES-6.0 Life Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ES6.1 Facility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ES6.2 BaBar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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ES-7.0 Maximum Possible Fire Loss (MPFL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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ES-8.0 Maximum Credible Fire Loss (MCFL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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ES-9.0 Fire Department Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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.........................................
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ES- 10.0 Recovery Potential
ES-11.0 Potential for Toxic. Biological. and Radiation Incident Due to Fire . . . . . . . . .
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ES-12.0 Emergency Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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ES- 13.0 Security Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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ES-14.0 Conclusions and Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main IR-2 Hall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electronics House . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Counting House (Building 621) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cryogenics Control/PEP Magnet Power Supplies (Building 624) . . . . . . . . . . . .
ToolShed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PEP-I1 Power/BaBar Solenoid Power (Building 625) . . . . . . . . . . . . . . . . . . . .
Gas Mixing House . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BaBar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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EXECUTIVE SUMMARY
ES-1.0 Introduction
This document summarizes the results of the Fire Hazards Analysis (FHA) prepared
for the BaBar Detector Project. The FHA was developed in accordance with the criteria
outlined in DOE Order 5480.7A [DOE, 19931 and is intended to address the major fire
hazards inherent in the Detector project. It includes evaluation of BaBar and related support
equipment and facilities, both within IR-2 and in adjacent support structures. A separate FHA
has been completed for the PEP-I1 ring and its support facilities.
National Fire Protection Association (NFPA) standards and DOE orders were used as
the baseline documents for this FHA. Data were gathered for this effort through field surveys
of PEP-I1 and the IR-2 facilities, meetings with members of the BaBar project team, and
review of available drawings, reports and related documents. Where required, selected
analyses were performed using recognized engineering methods, including handbook
correlations and computer based fire models.
ES-2.0 BaBar Facility
The BaBar Detector Project will be assembled and operated in the existing PEP-11
Research Hall at IR-2. This facility is large enough to accommodate BaBar, the radiation
shield wall, and the support services. It includes the main high bay area (Building 620), and
a cryogenics facility which includes a helium plant and control room. Also attached to the
main IR-2 hall is a room which houses the PEP-I1 magnet power supplies and various
electronics racks (Building 624). The two-story Counting House (Building 62 1) is located
north of the IR-2 hall. A tool shed is located outside directly adjacent to the east outside wall
of IR-2 between the two roll-up access doors.
1
In addition to the primary facility, a structure will be constructed to provide gas
mixing for BaBar. And, primary site power will be fed to the facility from a substation
adjacent to Building 625. These structures are located west of the IR-2 hall. Gas storage will
be located remotely from the gas mixing house with the gas supplies piped into the gas house,
mixed, and then piped to the IR-2 hall.
Site utilities, including power, water and sewer, are provided to the IR-2 facility.
Supply air for the IR-2 hall is provided from the PEP-I1 tunnel ventilation system. Exhaust is
also provided in the tunnel along with manually operated powered vents located on the roof
of the IR-2 hall. The two-story Counting House (Building 621) has an independent HVAC
system.
The IR-2 hall will be divided into two separate areas by a 7.9 m (26 ft) high radiation
shield wall. During operation of BaBar, a concrete curtain wall will be placed on top of the
shield wall, essentially providing a floor to roof barrier. At times when BaBar is being
serviced, the concrete curtain wall may be removed for crane access. When this occurs, there
will be a 5.8 m (19 ft) high opening between the top of the shield wall and the roof.
Initially, BaBar will be assembled and tested in the area east of the shield wall. It will
then be permanently located on the west side of the shield wall, aligned with the beam line.
After BaBar has been commissioned and experiments begun, the east part of IR-2 will house
electrical and data analysis support systems (Le., Electronics House), electrical panels and
motor control equipment, equipment staging areas, and limited fabrication capabilities.
Additional offices for support personnel as well as the main control center and an electronics
shop will be located in the adjacent two-story Counting Building (Building 621) along the
north wall of the IR-2 hall.
ES2.1 GonstructiodOccupancy Classification
The IR-2 hall is essentially a single-story structure with a floor area of approximately
897 m2 (9,660 ft2) and ceiling height of 13.7 m (45 ft). The structure is built of a
2
combination of reinforced concrete and insulated steel panels on structural steel framing. The
reinforced concrete is part of the PEP-I1 construction with a steel framed extension (garage).
The adjacent spaces, including the Counting House and the cryogenics control room, are also
constructed of steel panels on a structural steel frame.
The construction type is a mix of Type 11(111) and Type II(OO0) in accordance with
NFPA 220, Standard on the Types of Building Construction [NFPA, 19951. Both classes of
construction are noncombustible. The comparable construction types under the Uniform
Building Code are I1 (1 hour) and 11-N.
The IR-2 facility is classified as a Mixed Occupancy under the provisions of the NFPA
Life Safety Code, NFPA 101 VFPA, 19941. The Counting House (Building 621) which
houses the control center, electronics shop, and support offices is classified as a mixed
Business and Laboratory Occupancy. The remainder of the facility is classified as a Special
Purpose Industrial Occupancy. In general, the construction meets the requirements of the
NFPA 101 Life Safety Code and the Uniform Building Code in terms of fire resistance,
separation of fire areas, and egress capacity.
ES2.2 BaBar Equipment/Systems
A detailed description of BaBar design is provided in the Preliminary Safety
Assessment Document-BaBar [SLAC, 19961. The Detector (BaBar) design consists of a
silicon vertex detector, a drift chamber, a particle identification system, a cesium iodide (CsI)
electromagnetic calorimeter, a magnet with an instrumented flux return, electronics, and
computing systems.
The Detector weighs approximately 1,000 tons and is approximately 6.7 m in height,
9.5 m in width, and 8.3 m in length. Support equipment includes the following:
(1)
a cryogenic plant and storage dewars,
(2)
electronic signal processing equipment,
3
(3)
power supplies,
(4)
control systems,
(5)
mechanical support systems,
(6)
computing systems,
(7)
an electronics house, and
(8)
a detector transport system.
ES2.3 BaBar Support SystemdEquipment
Electronics House
An enclosure will be constructed and maintained on the east side of the shield wall in
IR-2 to provide data collection support to BaBar. The 74.3 m2 (780 ft2) enclosure will be
moved into place near the shield wall, and the electronics/signal cables will be extended from
the Detector to the Electronics House through a floor level cable tray system that passes
through the shield wall in two places. Instruments will be located in closed electronics
cabinets in the Electronics House. Additional instrument cabinets, transformers, HVAC, and
support equipment will be located on the roof of the House. A UPS unit for the Electronics
House will be positioned along the north wall of the IR-2 hall.
Cables will enter the electronics house into a 0.3 m (1 ft) high floor plenum and be
distributed to the appropriate cabinet(s). The individual cabinets as well as the enclosure will
be independently cooled to ensure control of ambient temperature conditions. Separate,
remote exits will be provided in the Electronics House.
Main Control Center
The main control center for BaBar is located on the first floor of the Counting House
(Building 621). Most of the signal/control cables are routed from BaBar through the
Electronics House and to the control center in cable trays.
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Cryogenics
A helium liquifier plant, a cryogenics control room, and the PEP magnet power supply
room are located outside the southeast corner of IR-2. Cables and gas supply lines are routed
from BaBar to the PEP power supply room or the cryogenics control room in cable trays
installed along the walls of the high bay area in IR-2. The cryogenics plant is fully automatic
and is controlled/monitored in the cryogenics control room.
Gas Mixing House/Gas Storage
The Gas Mixing House will be located on the apron above the IR-2 hall. The House
will receive make-up gases from the remote storage tanks. Mixing and control equipment,
including system interlocks to shut down the mixing process and the gas supplies, will be
installed. While the design of the Gas Mixing House has not been completed, it is the intent
to meet the requirements of NFPA 70 (NEC) and 101 in terms of electrical safety and life
safety. SLAC electrical and fire protection engineers in cooperation with the BaBar Safety
Officer will review and approve the final design.
Power Distribution
Building 625 houses the PEP-I1 power supplies and the BaBar solenoid power supply.
BaBar power supply cables are routed from Building 625 through the west exterior wall of
IR-2 through cable conduits. The cables are routed in cable trays installed along the walls of
the IR-2 hall.
Miscellaneous
A tool crib is located along the east wall of IR-2 between the two sets of roll-up
doors. The shed is wood framed construction with metal panels for the roof and walls.
5
Other equipment located outside IR-2 includes the following:
(1)
nitrogen dewar,
(2)
electrical substations,
(3)
chillers, and
(4)
storage trailers (unoccupied).
None of these items pose a direct fire hazard to the IR-2 facility.
ES-3.0 Fire Hazards
An analysis of potential fire hazards focussed on (1) incidents that may occur in the
Detector, and (2) incidents outside the Detector. In evaluating the impact of such incidents,
consideration was given to potential damage to the Detector and its support equipment as well
as to the facility. In addition, adverse effects on life safety were evaluated.
ES3.1 Bal3ar Fire Scenarios
During operation of BaBar, the likelihood of a fire incident is relatively low.
However, the potential impact is considerable, most likely taking BaBar out of service for an
extended period of time. The most likely fire scenario would involve an electrical ignition
source, burning of wire and cable jacketing, insulation materials, and possible ignition of gas
mixtures in the Detector.
While limited structural damage would occur to the IR-2 hall, particulate and
corrosive/toxic gases would spread into the PEP-I1 tunnel. The PEP-I1 tunnel is protected,
limiting the extent of damage. And, the immediate area of BaBar as well as the PEP-I1
tunnel will not be occupied while the Detector is operating. Therefore, the impact o f a fire in
the Detector on life safety under these conditions is negligible. Fire impact on the east side
of the shield wall is also expected to be negligible.
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The likelihood of a fire incident as well as the resulting impact is considerably greater
when BaBar is open for repairs, maintenance, and adjustments. An incident which occurs
during these periods will not extensively damage the IR-2 hall. But, higher burning rates and
faster flame spread rates will occur, resulting in higher volumes of smoke particulate and
combustion gases and higher temperatures. Damage to support equipment in the area of
BaBar and in the PEP-I1 tunnel would be greater under these conditions.
The risk of injury or death to individuals located in the BaBar area and in the tunnel
near IR-2 is relatively low provided appropriate egress procedures are followed. However,
the risk to an individual working inside BaBar is considerably higher. This area is identified ’
as a “permit required” confined space. Appropriate safety precautions and procedures will be
developed.
ES3.2 Candidate Exposure Fire Scenarios
Several candidate exposure fire scenarios were considered. These scenarios involved
ignition and burning of materials either in the immediate vicinity of BaBar, or on the east side
of the shield wall in the area of the IR-2 hall that will include the Electronics House.
Included were the following candidate scenarios:
(1)
cable tray fires adjacent to BaBar (west IR-2),
(2)
wood storage/equipment crates (east IR-2),
(3)
flammable liquid spills (east IR-2), and
(4)
Class A combustibles in open metal drums (east IR-2).
The impact on these candidate fire scenarios was based on the following effects:
(1)
exposure damage to high value equipment,
(2)
exposure damage to structural elements,
(3)
(4)
direct exposure damage to BaBar, and
adverse life safety conditions.
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The results of computer based analyses indicate that structural damage is unlikely due
to occurrence of any of these fires. Separation distances on the order of 2 m (6-7 fl) between
these types of fuels and the Electronics House will minimize the potential for damage to the
Electronics House.
The cable tray fire scenario poses a potential exposure problem for the Detector. It is
recommended that thermal detection, thermal radiation shielding, and firestopping be installed
to protect BaBar from a fire in the adjacent cable trays.
A fire involving as little as 23 kg (50 lb) of paper or trash in the Electronics House
can result in flashover of the House and exposure of BaBar to high temperatures and
corrosive gases (when the concrete curtain is not in place). Effective protection of the
Electronics House is required.
Incidental fires in adjacent spaces outside IR-2 are not expected to impact the IR-2 hall
or BaBar. Assuming available fire suppression systems operate and a fire department
responds, the fuel loading is too low to result in an extended fire duration.
ES-4.0 Fire Protection Features
ES4.1 Existing Features
The existing fire protection features include the following:
(1)
Water Supply: The site water supply is a combined domestic and fire water
system, provided by a 24 in. water main routed from the community of Menlo
Park. The system is looped, providing redundant supplies that exceed the twohour demand required in DOE 5480.7A.
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(2)
Fire Hydrants: There are four fire hydrants within 91.5 m (300 ft) of the IR-2
hall. Hydrant spacing and location meet the requirements of DOE Order
6430.1A.
(3)
Suppression Systems: The IR-2 hall is currently protected by a wet pipe
automatic sprinkler system which is in compliance with NFPA 13 for
“Ordinary” hazard protection. The Counting House, the cryogenic control
room, and the power supply building (Building 625) are currently protected by
wet pipe automatic sprinklers. The PEP-I1 beam tunnel is also protected by
sprinklers.
(4)
Fire Extinguishers: Fire extinguishers are located in each of the spaces
associated with the IR-2 hall and support areas, and are located in compliance
with NFPA 10. Most of the extinguishers are CO, type due to their
effectiveness on electrical/electronics fires.
(5)
Alarm System: The existing alarm system is an obsolete, high voltage system
that must be replaced.
(6)
Smoke Detectors: The existing smoke detectors are high voltage type and are
obsolete.
(7)
Pull Stations: Manual fire alarm pull stations are located in IR-2 and the
Counting House. The pull stations are connected to the site-wide alarm system.
(8)
Smoke ControWentilation: There are two roof-mounted, manually operable
exhaust fans in the IR-2 hall. The fan capacities are 18,400 cfm each. One is
located on each side of the shield wall. They are automatically shut off in the
event of a fire alarm and can be reactivated by the fire department.
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Supply ventilation and additional exhaust are provided to IR-2 from the PEP-I1
beam tunnel. The fans in the tunnel are also shut off in the event of a fire
alarm. The fire department can restart these fans as well as the fans in IR-2 to
assist in smoke evacuation of the tunnel or the IR-2 hall.
(9)
Fire and Smoke Barriers: The walls between the IR-2 hall and adjacent spaces
are not rated fire barriers. Under the occupancy use and anticipated
combustible loading, there are no requirements to subdivide the IR-2 hall or
separate it from the other buildings. Life safety requirements are also met
without further subdivision.
(1 0)
Emergency Response and Training: The SLAC site maintains a professionally
trained fire department on a 24-hour basis, seven days a week. Operations
within the Department include fire suppression, emergency medical, hazardous
materials response, and training/preplanning. Fire department response time to
the IR-2 hall is estimated at 3.5 to 4 minutes.
(1 1)
Fire Protection Related Run-off Concerns: None of the building areas
reviewed as part of this FHA have "loose" contamination which could be
spread by automatic sprinkler or firefighting efforts. None of the areas are
classified as "Contamination Areas." While the design limit for sprinkler flow
for a 20-minute period is a little over 4,500 gallons, this represents an extreme
worst case. Based on the combustible loading and sprinkler proximity in each
of the sprinklered areas, it is unlikely that more than one or two sprinklers will
activate. Assuming a 20-minute duration for two sprinklers, the total water
discharge is closer to 750 gallons.
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ES4.2 Planned Modifications/Additions
Additional fire protection features as well as modifications to existing features are
planned in support of the BaBar Detector Project. These features will require modifications to
existing fire protection features as well as incorporation of new protection systems.
Main IR-2 Hall
The primary fire alarm system in IR-2 will be replaced with Pyrotronics addressable
fire alarm panels and devices. The panels will be connected to the site-wide fire alarm system
and the Palo Alto Fire Department dispatch center. The ionization smoke detectors will be
replaced by system compatible, single-station photoelectric smoke detectors. In addition, an
HSSD (High Sensitivity Smoke Detector) system will be installed at the ceiling and two
intermediate levels in the west end of the main IR-2 hall, above BaBar. This system is
capable of multiple pre-alarm and alarm points, which can be adjusted to sensitivities
appropriate for the performance requirements during the BaBar Detector Project.
The automatic sprinkler system on the east side of the shield wall will be converted
from a wet system to a preaction system. The preaction valve will be operated by
photoelectric detector response at the ceiling of the IR-2 hall.
Consideration is also being given to removal of the automatic sprinkler system on the
west side of the shield wall. Due to the low fuel loading, high ceiling and number of
obstructions, the sprinkler system is not expected to be effective. Incidental fires, if they
occur, will be too small to result in timely response by the sprinkler system. And, most fires
will occur in highly obstructed areas, including in the Detector, in support electronics racks or
in the cable trays. Water sprays from ceiling level sprinklers will have little or no effet on
such fires. These fires are not expected to result in extensive damage to the IR-2 hall due to
the inherent fire resistance of the construction. In addition to the lack of effectiveness, the
crystals located in the calorimeter subsystem of the Detector are highly susceptible t o
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hydroscopic damage. Minor amounts of water can effectively result in BaBar being out of
service for an extended period.
Electronics House
Both fire detection and suppression systems will be installed in the Electronics House.
It is critical to continued operation of the BaBar Detector Project that the impact of any
incidental fires in the Electronics House be minimized. Based on discussions with the
designers of the Electronics House and several of the users, the fire protection design has been
developed to ensure that damage from fires is limited to only part of an electronics rack,
whether the fire starts in a rack or outside the rack in the enclosure.
Very early detection is necessary in order to have any chance of meeting such an
objective. HSSD systems will be installed in each electronics cabinet and in the cable plenum
under the floor. Selected electronics cabinets located on the roof of the enclosure will also
utilize HSSD detection. Such systems are capable of detecting initial pyrolysis products at an
order of magnitude less concentrations than conventional smoke detection while minimizing
false alarms. Photoelectric smoke detectors will also be installed in each double rack.
A CO, suppression system will be installed to protect the inside of each electronics
rack and in the underfloor cable plenum. Discharge of the CO, system in the electronics
racks will result from cross-zoned detection by the HSSD system and the photoelectric
detector in each double electronics rack or in the underfloor plenum.
In addition to these features, single-station photoelectric smoke detectors and preaction,
quick response automatic sprinklers will be installed in the Electronics House. The preaction
valve will be operated as a result of photoelectric detector response, charging the sprinkler
system piping with water. The detection systems will be connected to the primary fire alarm
system.
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Power and signal interruption will be automatic, tied to temperature monitoring of the
electronics or smoke detection interlock. Power interruption will also include most of the
electronics racks supplied by the UPS systems provided in support of the Electronics House.
There will be several racks that cannot be de-energized automatically due to the potential for
considerable damage to the Detector and selected support equipment.
Counting House (Building 62 11
An addressable fire alarm system with single-station photoelectric smoke detectors will
be installed throughout the Counting House, in compliance with NFPA 72. The wet pipe
sprinkler system will be modified to perform as a preaction system. The preaction valve will
be operated based on smoke detector response.
Cryogenics Control/PEP Magnet Power Supplies(Bui1ding 624)
The cryogenics control room and the PEP Magnet Power Supply room are adjacent to
each other on the south side of the IR-2 hall. These spaces will be protected by standard wet
sprinkler systems, designed to protect ordinary hazards.
Tool Shed
An existing shed located on the east outside wall of IR-2 between -the two roll-up
doors will be used as a tool shed. The shed will be protected by a standard wet pipe sprinkler
system.
PEP-11 Power/BaBar Solenoid Power Building (Building 625)
The currently installed wet pipe sprinkler system will remain in service in this
building. In addition, photoelectric smoke detectors will be installed and connected t o an
addressable fire alarm panel for signaling to the site wide fire alarm system.
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Gas Mixing House
The final design of the Gas Mixing House has not been completed. Current plans
include volumetric and mass flow monitoring from the Gas House to BaBar with automatic
interlock to shut down gas flow. Consideration will also be given to gas detection, smoke
detection, automatic ventilation (interlocked), and automatic sprinklers in this building.
BaBar Fire Protection
The dominant fire hazards associated with BaBar are electrical/electronic ignition
sources, flammable materials such as wire and cable jacket insulation, polystyrene thermal
insulation, and the gas systems. The discussion presented in this section is limited to the fire
safety features currently included in the Detector design or under consideration.
Due to equipment sensitivity, performance demands and space restrictions within
BaBar, the use of conventional fire protection systems to protect the Detector from an internal
fire would not be performance or cost effective. A more appropriate approach involves fire
prevention, passive methods to limit fire growth, and very early detection.
The use of water based or gaseous suppression systems in BaBar is not recommended.
The introduction of water into the Detector subsystems (intentionally or accidentally) will
result in significant damage. In addition, overpressure conditions resulting from internal
injection of gaseous suppression agents will result in considerable damage in the Drift
Chamber. As a result of these problems, alternative fire protection features will be used.
Limiting Materials ’ Flamma bility
The materials used in BaBar will be restricted in terms of their flammability
characteristics in order to minimize the ignition potential and limit the fire growth and spread
rate potential. Insulating materials will be fire retardant treated, with the exception o f a
limited number of applications where fire retardant additives could react adversely due to the
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environment in the Detector. An example is in the Drift Chamber where conventional
bromated materials would absorb free electrons, adversely affecting the experiment.
Cable and Wire Flammability Specification
A detailed wire and cable specification has been developed and implemented to limit
potential ignition and fire propagation in BaBar. These insulating materials comprise the
largest source of fuel for an internal fire. Therefore, the specification was developed to
restrict the flammability of wire and cable insulation wherever practical.
It should be noted that minor deviations are expected on a case by case basis due to
availability problems associated with limited quantities of special purpose wire and cable.
Each deviation must be approved by the BaBar Control Board in consultation with the BaBar
Safety Officer and the SLAC Fire Protection Engineer.
Gas Systems
The gas systems to be used in the Drift Chamber and the RPC Chamber will be
formulated to ensure that the resulting gas mixtures are outside the flammable limits under
normal operation of the Detector. The current anticipated mixture for the Drift Chamber
includes 80 percent helium and 20 percent isobutane. The 20 percent isobutane results in this
mixture being above the upper flammable limit (UFL) and, therefore, will not burn. The
isobutane volume in the mixture must be reduced to 6 percent (vol) to have a flammable
mixture. This corresponds to approximately a 3 to 1 dilution of the butane-helium mixture
with air.
The candidate gas mixture for the RPC is comprised of isobutane, argon, and Halon
134A. The Halon 134A is fixed at 30 percent (vol). The volume concentrations of the
isobutane and argon are still being evaluated. The flammability of the mixture will b e kept
below the lower flammable limit. A detailed analysis of the flammability hazards o f the gas
mixtures was performed as part of this effort.
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Process/Detector Safety Concerns
A dominant safety feature that will be employed is process control. Thermal
conditions, pressure variation, gas detection, gas compound mass and volume flow rates, and
oxygen depletion will be monitored continuously. Interlock systems will be installed that will
shut down parts or all of the Detector as well as power and gas supplies if conditions vary
outside established operational and safety limits.
Smoke Detection
High sensitivity smoke detection (HSSD) will be installed in the Detector, providing
shutdown capability and a fire alarm signal. This system will be adjusted to detect very low
concentrations of combustion products.
Nitrogen Inerting
During operation, the calorimeter will be inerted with nitrogen (N2) reducing the
oxygen concentration below 10 percent. This can significantly reduce the ignitability and
burning rates of materials in the Detector. When the Detector is open for maintenance or
modifications the N, may be replaced by dry air. This will increase the risk somewhat.
Electrical/Signaling Systems
All power and signaling systems supporting BaBar will be grounded and tested in
accordance with NFPA 70, The National Electrical Code [NFPA 70, 19961, before initial
operation.
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Electronics Support Racks
Approximately ten enclosed racks will be located adjacent to BaBar. These racks will
be protected by HSSD detection. Consideration will also being given to installation of a CO,
suppression system to protect these racks.
Cable Tunnel Protection
The 0.6 m x 1.8 m (2 ft x 6 ft) cross-section cable tunnel which connects the
electronics from BaBar to the Electronics House will be firestopped at each end with
vermiculite bags. The objective is to minimize the potential exposure of the Detector to a
cable fire which propagates from the Electronics House side of the shield wall.
BaBar Exposure Protection
The primary exposure hazards to BaBar are (1) a potential cable tray fire, and (2) an
equipment or maintenance activity fire outside the Detector.
Cable Tray Protection
The horizontal cable trays on the west wall of the IR-2 hall will be firestopped every
6.1 m (20 ft) using vermiculite filled bags or equivalent to limit both vertical and horizontal
fire propagation. The vertical trays will be firestopped every 3 m (10 ft). In addition,
thermal radiation shielding will be installed between the Detector and the PEP cable trays on
the west side of the Detector. This is the location that is closest to the cable tray array that
runs along the west wall and is most vulnerable to damage due to thermal radiation from a
propagating fire in the cable trays.
Consideration will be given to installing fire barrier separations between the cable trays
along the west wall of IR-2 to limit the potential for tray to tray fire spread. It is also
recommended that thermal detector wire be installed in each cable tray and connected to the
17
BaBar control panel and.the addressable fire alarm system. This will provide detection of
"hot" spots in the cable trays prior to flaming conditions. BaBar shutdown and intervention
can be achieved before it is exposed to contaminating combustion products, including acid
gases and particulates.
ElectricaUSupport Equipment
All equipment located permanently or temporarily adjacent to the Detector will be
installed and operated in compliance with NFPA 70. Electronics racks will be protected by
photoelectric detection. Localized in-cabinet CO, suppression is under consideration.
Housekeeping and Administrative Controls
Procedures will be developed by the BaBar Safety Officer to address general
housekeeping in the Detector area, limits on combustibles, and operation and maintenance
activities. Implementation of standard industrial practices regarding hazardous processes will
be done in cooperation with the SLAC Safety Health and Assurance Department. Equipment
that pose specific fire exposure hazards such as propane fueled forklifts and welding
equipment will be removed from the Detector area after any needed use. The use of such
equipment will be monitored closely to ensure compliance with industrial safety practices.
ES-5.0 Property and Equipment Criticality
ES5.1 Safety Class EquipmentNital Safety Systems
There are no safety class items (SCI) or vital safety systems (VSS) located in the IR-2
hall or as part of the BaBar Detector Project. The risk of significant threats to public safety
or the environment are considered negligible.
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ES5.2 High Value Property
High value property is defined in DOE Order 5480.7A as property with a replacement
cost of $500,000 or greater. The Detector (BaBar) ($70 M), the Electronics House ($10 M),
the Cryogenics Plant ($3 M), and the Main Control Room ($500 K) are considered high value
properties. The estimated replacement value of IR-2 is $10 M.
ES5.3 Critical Process Equipment
As defined in DOE 5480.7A, critical process equipment in excess of six months to be
replaced if damaged or destroyed, and is normally associated with equipment used in
processing Special Nuclear Materials (SNM).
There is no critical process equipment associated with the BaBar Detector Project.
However, it should be noted that several components of the Project including the Detector,
Electronics House, and the Cryogenics Plant, if exposed to a serious fire, would require in
excess of six months to restoreheplace.
ES-6.0 Life Safety Considerations
ES6.1 Facility
The BaBar facility is classified as a Special Purpose Industrial occupancy in
accordance with NFPA 101, “The Life Safety Code” (LSC). Based on this classification and
review of the existing and planned contents, the facility’s level of hazard from contents is
Ordinary.
The normal working staff in the facility during installation and operation of the
Detector is significantly below limits established in the LSC for this type of occupancy. Due
to congested conditions, visitor access to this space will be limited.
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Based on requirements in the LSC for Special Purpose Industrial occupancies, the
facility has adequate provisions for egress, including travel distances, number and location of
exits, avoidance of dead-end travel paths, and lighting and marking of exits.
ES6.2 BaBar
Under operating conditions, personnel will not be located on the west side of the
shield wall. Therefore, there are no life safety problems other than to ensure that these
restrictions are maintained.
During periods when BaBar is shut down for maintenance or modifications, personnel
will be located in the area where the Detector is located. In addition, personnel will be
required to enter the Detector (while in the open position) to perform necessary adjustments
on the subsystems. The area inside BaBar is a “permit required” confined space and will
likely only accommodate a single person.
An analysis of the fire exposure risk to individuals working inside BaBar is outside the
scope of this FHA and dependent on the final Detector subsystem designs.
ES-7.0 Maximum Possible Fire Loss (MPFL)
The MPFL for the BaBar Detector Project involves a fire in BaBar while open. The
damage resulting from this fire scenario will include loss of several, if not all, of the
subsystems and require considerable resources for restoration. Significant structural damage
to the IR-2 hall is not expected.
The replacement cost for BaBar is estimated at $70 M. Clean-up costs for thermal and
corrosion damage to the support equipment in the IR-2 hall and the PEP-I1 tunnel is estimated
at $8.0 M, resulting in a total MPFL of approximately $78.0 M.
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ES-8.0 Maximum Credible Fire Loss (MCFL)
The MCFL for the BaBar Detector Project also involves a BaBar fire. However, the
use of flammability requirements, HSSD detection, and machine control systems is expected
to limit the damage somewhat. Replacement costs are estimated at $35 M or less, depending
on the extent of implementation of these fire protection features. In addition, extensive
damage to the PEP-I1 tunnel and support equipment is not expected. Clean-up costs are still
estimated at $8.0 M, resulting in a total MCFL of $43.0 M.
ES-9.0 Fire Department Response
SLAC operates an on-site, fully staffed and well trained fire department. The
department is capable of handling a fire in the IR-2 hall. The response time is estimated at
from 3.5 to 4 minutes, with an additional 3 to 5 minutes for staging activities and initiation of
interior firefighting.
ES-10.0 Recovery Potential
The limited combustible loading minimizes the severity of anticipated fires in the
buildings associated with the BaBar Detector Project. The heavy reinforced construction of
the west end of IR-2 is unlikely to sustain significant damage, even by the most severe fires
that were considered possible under the planned occupancy. In addition, current anticipated
combustible loadings for the east end of IR-2 as well as in the adjacent buildings (Buildings
621, 624, and Cryogenics Control Room) are low enough that clean up and repair due to an
incidental fire will be an acceptable strategy.
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ES-11.0 Potential for Toxic, Biological, and Radiation Incident Due to Fire
There are no biological agents stored or used in this facility. The potential for a toxic
materials incident due to fire is limited. Ignition and burning of wire and cable insulation,
ignition of a limited volume of flammable gas or liquid or burning of incidental Class A
materials will generate some amount of toxic combustion products. The hazard associated
with these releases depend on the ignition scenario, the location of the incident, and the
proximity of occupants but is expected to be confined to the building.
The primary source of radiation is the calibration source for the Calorimeter.
However, the source is enclosed and protected. Radiation from the experiment will normally
be contained to the Detector. Radiation from the BaBar experiment occurs inside the
interaction point from the beam and is normally contained within the Detector. In the event
of a fire, the beam is interrupted. In addition, there are redundant entry doors that
automatically interrupt the beam when opened. Under such conditions, any radiation release
will be minor and confined to the west end of the IR-2 hall due to the placement of the shield
wall and the concrete curtain wall which extends across the width of the hall and from the
floor to the roof. Minor leakage is possible around the perimeter of the curtain wall, but the
level of exposure would be minimal. In an emergency, the Fire Department can enter the
west end of IR-2 after the beam is interrupted with no health hazard.
ES-12.0 Emergency Planning
The BaBar Safety Officer and the Safety Health and Assurance Department
Coordinator will prepare a comprehensive Emergency Plan for the BaBar Detector Project.
The Plan will include guidance for evacuation and emergency procedures for the IR-2 hall
and support buildings associated with BaBar.
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ES-13.0 Security Considerations
The security measures currently contemplated for BaBar including restricted access
during Detector operation, will not compromise fire protection or life safety considerations.
ES-14.0 Conclusions and Recommendations
The fire hazards and associated risks related to the BaBar Detector Project warrant
preventative or mitigative strategies consistent with the loss limitations stipulated in DOE
5480.7A. The following recommendations result from the analysis outlined in the FHA,
consideration for cost-effective strategies to maintain the BaBar Detector Project for an
extended period without significant interruption, and assurance of adequate life safety.
Consideration should be given to all of the following recommendations. Failure to
implement a particular recommendation should be carefully reviewed since trade-offs and
dependencies are affected.
(1)
Prepare an emergency preplan for the Project.
(2)
Establish administrative controls to limit combustibles and hazardous processes.
Main IR-2 Hall
(1)
Install addressable fire alarm system, connected to site-wide fire alarm system
and the Palo Alto Fire Department dispatch center.
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(2)
Install photoelectric single-station smoke detectors in IR-2 and a HSSD system
at the ceiling and two intermediate levels on the west side of the shield wall.
(3)
Convert the automatic sprinkler system in IR-2 to a preaction system, crosszoned to photoelectric smoke detectors. Removal of the automatic sprinkler
system on the west side of the shield wall can be done if all of the
recommendations associated with BaBar and the cable trays are implemented.
(4)
Install thermal detection wire in the cable trays along the walls near the
Detector and in trays that supply cables to the Detector.
(5)
Install a thermal radiation barrier between the Detector and the horizontal cable
tray array located on the west wall of IR-2. Consider providing fire barrier
separations between each cable tray along the west wall to limit the potential
for fire spread to adjacent trays.
(6)
Provide firestopping at 3 m (10 ft) intervals for vertical cable trays and 6 m
(20 ft) for horizontal cable trays in the west area of IR-2 to reduce the potential
fire exposure to the Detector in the event of an ignition in a cable tray.
(7)
Restrict combustibles in the IR-2 hall. Limit flammable liquids to 7.6 L (2 gal)
quantities in any single unprotected area @e., outside a listed flammable liquids
cabinet). Also, restrict the number of wood packing crates and similar
materials to 400-500 kg (900-1000 lb) in any single area. (This is roughly
equivalent to two of the large crates analyzed in Appendix B of the FHA.)
(8)
Provide a 2 m (6.6 ft) separation distance from combustibles and the
Electronics House and structural columns.
(9)
Maintain manually operated roof exhausts with controls accessible to the fire
department.
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(10)
Do not install a solid barrier at the entrances to the PEP-I1 tunnel open to take
advantage of the tunnel volume for ventilating fire gases away from the
Detector. (Note that the PEP-I1 tunnel is protected by automatic sprinklers and
will not sustain serious damage under this strategy.)
Electronics House
Install preaction sprinklers (quick response type) and photoelectric smoke
detectors in the enclosure. The preaction sprinkler valve should be operated
based on smoke detector activation.
Install HSSD detection in each enclosed electronics racks and in the underfloor
cable plenum. Provide photoelectric detectors in each double rack and in the
plenum.
Install automatic CO, suppression for the enclosed racks and underfloor
plenum. The systems should be initiated based on cross-zoned response of a
photoelectric detector and the HSSD system.
Provide for automatic power and signal interruption tied to electronics
temperature monitors and the smoke detector system.
Restrict the amount of ordinary combustibles (Le., <23 kg (50 lb) stored
outside metal cabinets in the Electronics House.
Counting House (Building 62 1)
(1)
Install addressable fire alarm system with single-station, photoelectric smoke
detectors throughout in accordance with NFPA 72.
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(2)
Convert automatic sprinkler system to a preaction type; the system valve will
be operated as a result of detection by the photoelectric smoke detectors.
(3)
Restrict storage of combustibles and obstructions along egress paths.
Cryogenics Control/PEP Magnet Power Supplies (Building 624)
Protect both spaces with standard wet automatic sprinkler systems.
Install photoelectric smoke detectors and addressable fire alarm.
Protect with standard wet automatic sprinkler system.
PEP-I1 PowedBaEIar Solenoid Power (Building 625)
(1)
Install photoelectric smoke detectors and addressable fire alarm.
(2)
Maintain existing standard automatic sprinkler system.
Gas Mixing House
(1)
Design in accordance with NFPA 101 and 70, including grounding and
explosion protection for equipment.
(2)
Provide gas flow control, continuous monitoring, and automatic gas flow
interruption.
(3)
Include smoke detection, automatic sprinklers, and automatic ventilation
(interlocked).
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(4)
Construct in accordance with the Uniform Building Code.
(1)
Limit wire and cable flammability as outlined in memorandum: “BaBar Fire
BaBar
Protection Requirements for Wire and Cable” [SLAC, 7/3 1/96].
(2)
Minimize the use of non-fire retardant insulation materials.
(3)
Maintain gas compounds outside the flammability limits.
(4)
Maintain process control through use of temperature, pressure, and oxygen
monitoring, gas detection, and gas compound mass and volume flow rates.
Incorporate interlocks to interrupt gas flow, power and affected parts of the
Detector if conditions vary outside established operational and safety limits.
(5)
Install HSSD smoke detection in the Detector, providing shut down and alarm
signaling.
(6)
During operation, inert the calorimeter with nitrogen to an oxygen
concentration below 10 percent (vol).
(7)
Provide photoelectric detection and consider automatic CO, suppression in the
enclosed support electronics racks adjacent to BaBar.
(8)
Protect the cable tunnel which connects BaBar to the Electronics House at each
end with firestopping.
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