Information Notice 1999-05, Inadvertent Discharge of Carbon Dioxide Fire Protection System and Gas Migration
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555-0001
March 8, 1999
NRC INFORMATION NOTICE 99-05: INADVERTENT DISCHARGE OF CARBON DIOXIDE
FIRE PROTECTION SYSTEM AND GAS MIGRATION
Addressees
All holders of licenses for nuclear power, research, and test reactors, and fuel cycle facilities.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is Issuing this Information notice to alert
addressees to potential personnel safety hazards and operational complications associated with
discharge of carbon dioxide (C02) fire protection systems. It Is expected that recipients will
review the Information for applicability to their facilities and consider actions, as appropriate.
However, suggestions contained In this Information notice are not NRC requirements; therefore, no specific action or written response to this notice Is required.
Background
At Duane Arnold Unit I on March 22, 1992 (LER 331/92-004), the licensee performed a special
test of the C02 fire suppression system In the cable spreading room. This test was conducted
to check corrective actions taken following a C02 discharge In 1990. At the time of this test, the reactor had been shutdown and defueled. As a result of this test, C02 had Intruded into the
control room; this Intrusion led to an unacceptable reduction In area oxygen level within a few
minutes. Oxygen levels of 17 percent (at chest level) and 15 percent (at floor level) were
recorded; these levels were below the plant acceptance criterion of 19.5 percent. Essential
control room personnel donned self-contained breathing apparatus (SCBA) and were able to
remain In the control room. The lowered oxygen levels were caused by increased pressure In
the cable spreading room which Is directly beneath the control room. Sealed penetrations
between the two rooms leaked under the high differential pressure.
On July 28, 1998, at the Idaho National Engineering and Environmental Laboratory, during
preparation for electrical system preventive maintenance, a high-pressure C02 fire suppression
system unexpectedly actuated. The room In which workers were located was filled instantly
with C02, creating whiteout conditions. Workers did not have the means of escaping safely.
Emergency exit training was not provided; exit pathways were not dear, and, emergency
breathing apparatus, exit pathway lighting, and emergency ventilation were not available. The
accident resulted In one fatality, several life-threatening Injuries, and significant risk to the
safety of the Initial rescuers. The Accident Investigation Board determined that since 1975 there have been a total of 63 deaths and 89 inJuries resulting from accidents Involiing the
discharge of C02 fire suppression systems.
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IN 99-05 March 8, 1999
Description of Circumstances
On January 15, 1999, at 5:49 p.m., with the plant at full power, an Inadvertent discharge of the
C02 fire suppression system occurred In the Millstone Unit 3 cable spreading room. At
Millstone 3, the cable spreading room is located In the control building directly below the control
room. The actuation was caused when a non-licensed plant equipment operator trainee In the
service building blew dust off a printed circuit board located In the cable spreading room C02 control panel. The panel Is located in the service building, not the control building. There were
no plant personnel In the cable spreading room at the time of the discharge. Shortly after the
discharge, C02 was found to have migrated down Into the swltchgear rooms located directly
below the cable spreading room. Approximately 37 minutes after initiation, the licensee used a
portable Instrument to measure the concentration of C02 In one of the Control Building
stairwells (which allows access to the control room, the cable spreading room and the
switchgear rooms). The reading was off-scale high Indicating that the C02 concentration was
in excess of 50,000 parts per million (ppm). The current NRC Regulatory Guide 1.78 recommended toxicity limit for C02 is 10,000 ppm'. On the basis of this Indication, the licensee
declared the area uninhabitable.
Approximately 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> after the C02 discharge, operators aligned the control building purge
system to remove C02 from the switchgear rooms. The switchgear rooms were selected for
purging first because they contained important plant equipment, such as the auxiliary shutdown
panel. The purge system Is a non-safety-related system designed to remove C02 and smoke
from various control building areas. Placing the purge system in service diverted air from the
control room to the switchgear rooms which lowered the pressure In the control room relative to
the cable spreading room. This lowering of pressure in the control room may have allowed
C02 from the cable spreading room to migrate up through penetrations Into the control room.
When the concentration of C02 reached 5000 ppm In the control room, the operators donned
self-contained breathing apparatus (SCBA) as required by their procedures. The concentration
of C02 In the control room reached a peak level In excess of 17,000 ppm before It began to
decrease. The operators wore SCBA for approximately 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> until the C02 was successfully
purged from the control room.
Discussion
A review of this event by the licensee Identified several design and personnel safety Issues.
The cable spreading room C02 system Is designed to automatically actuate In response to a
fire. The system is equipped with alarms to warn personnel In the cable spreading room of an
Impending discharge of C02 to allow time to evacuate the cable spreading room.. In response
lThe current NRC toxicity limit for C02, specified in Reg. Guide 1.78, is 10000 ppm. Plant
personnel exposed to C02 need to be protected by self contained breathing apparatus before this
concentration is reached. In the proposed revision to Reg. Guide 1.78, the toxicity limit for C02 was
raised to 40000 ppm. Whis new limit is based on the Immediately Dangerous to Life and Health (IDLE)
concentration of C02, established by the National Institute for Occupational Safety and Health (NIOSH).
IN 99-05 March 8, 1999 to several previous Inadvertent actuations, the licensee had previously modified automatic C02 fire protection systems In other areas of the plant so that they could only be actuated manually.
After the January 15, 1999 event, the licensee disabled the automatic function of the C02 system for the cable spreading room and Implemented appropriate compensatory measures.
The licensee Is evaluating permanent changes to avoid future Inadvertent C02 discharges.
The migration of C02 Into three separate fire zones may have adversely affected the operators'
ability to shut down the plant during a fire in the cable spreading room. A severe fire In the
cable spreading room may adversely affect the operators' ability to safely shut down the plant
from the control room. In the event that the operators are required to evacuate the control
room, plant procedures require operators to shutdown the plant from the auxiliary shutdown
panel and other panels which are located In the switchgear rooms. During this event, the C02 concentration at the auxiliary shutdown panel would prohibit access without SCBA.
In 1996 the licensee established a site wide fire brigade. In 1997, the licensee suspended the
formal SCBA training and qualification program for plant operators except those who were
members of the fire brigade. This determination was based on projected post-accident radiation
levels and Intrusion of toxic gases Into the control room from outside sources. However, this
determination failed to consider C02 a toxic gas as recommended In NRC Regulatory Guide
1.78. Fortunately, during this event, SCBA were available in the control room area and at
various other locations around the site. Although training and qualifications for all plant
operators were not current, all the plant operators that were on shift during the event had
previously been trained and qualified with the SCBA and consequently they were able to
perform their duties using the SCBA. To improve communication between the operators, the
licensee replaced the Unit 3 SCBA with SCBA from Unit 2 which had an improved type of radio
communication system. In addition, some of the operators did not have corrective lenses
which were compatible with the SCBA face masks. As an Immediate corrective action the
licensee re-qualified all plant operators for SCBA use. The licensee Is evaluating the need to
reinstate the SCBA qualification program for plant operators on a permanent basis. This
suspension of SCBA quarffication was for plant operators only and did not affect fire brigade
members who were trained and qualified.
The discharge of C02 set off a security alarm on the cable spreading room door. A security
officer was Instructed to check the door alarm but to not open the door. The guard entered the
stairwell and ascended the stairs to the cable spreading room. Upon approaching the cable
spreading room, the officer smelled wintergreen (which Is discharged with the C02 to produce
an odor for personnel safety) and was engulfed In a mist that he concluded was C02. The
officer held his breath and rapidly exited the building. The Uoensee's root cause team
recommended that procedures for isolating areas potentially affected by C02 be reviewed.
IN 99-05 March 8, 1999 This Information notice requires no specific action or written response. If you have any
questions about the information In this notice, please contact one of the technical contacts
listed below, the appropriate regional office, or the appropriate office of Nuclear Reactor
Regulation (NRR) Project Manager.
David B. Matthews, Director
Division of Regulatory Improvement Programs
Office of Nuclear Reactor Regulation
Technical contacts:
Beth Korona, Region I
860-447-3170
E-mail: bek(&nrc.aov
Frank Amer, Region I
610-337-5194 E-mail: fiafnrc.aov
Chuck Petrone, NRR
301-415-1027 E-mail: cdp@nrc.gov
Peter S. Lee, NMSS
301-415-8111 E-mail: psll@nrc.gov
Attachments:
1. List of Recently Issued NMSS Information Notices
2. List of Recently Issued NRC Information Notices
Attachment I
March 8, 1999 LIST OF RECENTLY ISSUED
NMSS INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
99-04 Unplanned Radiation Exposures
311/99 All radiography licensees.
to Radiographers, Resulting From
Failures to Follow Proper Radiation
Safety Procedures
99-03
99-02
99-01
Exothermic Reactions Invoking
Dried Uranium Oxide Powder
(Yellowcake)
Guidance to Users on the
Implementation of a New
Single-Source Dose-
Calculation Formalism and Revised
Air-Kerma Strength Standard
for Iodine-125 Sealed Sources
Deterioration of High-Efficiency
Particulate Air Fitters In a
Pressurized Water Reactor
Containment Fan Cooler Unit
1/29199
1121199
1/20199
All operating uranium recovery
facilities that produce oxide
powder (U308) (yellowcake)
All medical licensees authorized to
conduct brachytherapy
treatments.
All holders of licences for nuclear
power, research and test reactors;
and fuel cycle facilities.
98-33 Regulatory
NRC Regulations Prohibit
Agreements that Restrict or
Discourage an Employee from
Participating In Protected Actvities
81298
All holders of a Nuclear
Commission license
98-30
97-91 Supp. I
98-20
Effect of the Year 2000
Computer Problem on NRC
Licensees and Certificate Holders
Recent Failure of Control
Cables Used on Amersham
Model 660 Posilock Radiography
Systems
Problems With Emergency
Preparedness Respiratory
Protection Programs
8/12/98
8110198
6/3/98
All material and fuel cycle
licensees and certificate holders
All industrial radiography
licensees.
All holders of operating licenses
for nuclear power reactors; non- power reactors; all fuel cycle and
material licensees required to
have an NRC-approved
Attachment 2
March 8, 1999
Page 1 of I
LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
99-04
Unplanned Radiation Exposures
to Radiographers, Resulting From
Failures to Follow Proper Radiation
Safety Procedures
311/99 All radiography licensees.
S9-03
99-02
99-01
9845
98-44
Exothermic Reactions Involving
Dried Uranium Oxide Powder
(Yellowcake)
Guidance to Users on the
Implementation of a New
Single-Source Dose-
Calculation Formalism and Revised
Air-Kerma Strength Standard
for Iodine-125 Sealed Sources
Deterioration of High-Efficiency
Particulate Air Filters In a
Pressurized Water Reactor
Containment Fan Cooler Unit
1/29199
1121/99
0112099
All operating uranium recovery
facilities that produce oxide
powder (U30g) (yellowcake)
All medical licensees authorized
to conduct brachytherapy
treatments.
All holders of licenses for nuclear
power, research and test reactors;
and fuel cycle facilities.
All holders of operating licenses
for nuclear power reactors, except
those that have permanently
ceased operations and have
certified that fuel has been
permanently removed from the
reactor.
All holder of operating licenses
for nuclear power reactors, except
those that have permanently
ceased operations and have
certified that fuel has been
permanently removed from the
reactor
Cavitation Erosion of Letdown Line 12115198
Orifices Resulstin In Fatigue Cracking
of Pipe Welds
Ten-year Inservice Inspection
12/10/98 (ISI) Program Update for Ucensees
that Intend to Implement Risk-Informed
ISI of Piping
Operating License
CP = Construction Permit
IN 99-05 March 8, 1999 This information notice requires no specific action or written response. If you have any
questions about the information in this notice, please contact one of the technical contacts
listed below, the appropriate regional office, or the appropriate office of Nuclear Reactor
Regulation (NRR) Project Manager.
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Division of Regulatory Improvement Programs
Office of Nuclear Reactor Regulation
Technical contacts:
Beth Korona, Region I
860-447-3170
E-mail: bekZnrc.aov
Frank Amer, Region I
610-337-5194 E-mail: fiaL&-nrc.gov
Chuck Petrone, NRR
301-415-1027 E-mail: cdpenrc.gov
Peter S. Lee, NMSS
301-415-8111 E-mail: psll@nrc.gov
Attachments:
1. List of Recently Issued NMSS Information Notices
2. List of Recently Issued NRC Information Notices
- See Previous Concurrence
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IN 99-XX
March xx, 1999 This information notice requires no specific action or written response. If you have any
questions about the information in this notice, please contact one of the technical contacts
listed below, the appropriate regional office, or the appropriate office of Nuclear Reactor
Regulation (NRR) Project Manager.
David B. Matthews, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts:
Beth Korona, Region 1
860-447-3170
E-mail: bek(&nrc.aov
Frank Amer, Region 1
610-337-5194 E-mail: fiaL&nrc.aov
Chuck Petrone, NRR
301-415-1027 E-mail: cdp@nrc.gov
Peter S. Lee, NMSS
301-415-8111 E-mail: psll@nrc.gov
Attachments:
1. List of Recently Issued NMSS Information Notices
2. List of Recently Issued NRC Information Notices
- See Previous Concurrence
DOCUMENT NAME: G:\\CDP\\MILCO2\\INCO2_C.WPD
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