Information Notice No. 89-44: Hydrogen Storage on the Roof of the Control Room
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
April 27, 1989
Information Notice No. 89-44: HYDROGEN STORAGE ON THE ROOF OF THE
CONTROL ROOM
Addressees:
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose:
This information notice is provided to alert recipients to potential generic
problems pertaining to the storage of hydrogen in the vicinity of safety-
related structures and air pathways into safety-related structures. It is
expected that recipients will review the information for applicability to
their facilities and consider actions, as appropriate, to avoid similar
problems. However, suggestions contained in this information notice do
not constitute NRC requirements; therefore, no specific action or written
response is required.
Description of Circumstances:
During the Region V Chemistry Team Inspection at the Trojan Nuclear Plant
the week of April 17, 1989, the inspectors identified a potential safety
problem concerning the location of the hydrogen storage facility. Hydrogen
is used on pressurized water reactor (PWR) plants for (1) providing a cover
gas in the volume control tank, and (2) for cooling the main turbine
generator. At boiling water reactor (BWR) plants, hydrogen is also used for
cooling the main turbine generator and for injection into the feed system for
plants which have implemented hydrogen water chemistry. The Trojan hydrogen
storage facility is located on the control room roof which is 30-inch-thick
reinforced concrete. The following potential safety problems were identified
during the Region V Chemistry Team Inspection:
1. Leakage of hydrogen gas from the storage facility in proximity to the air
intakes to the control room ventilation and emergency pressurization
system may introduce a flammable or explosive gas mixture into the
control room. Because the hydrogen storage facility, containing four
8,000-scf hydrogen tanks at up to 2450 psig, is Seismic Category II, a
seismic event may result in a hydrogen leak. Furthermore, the pressure
relief valves in the hydrogen facility exhaust downward to within 6
inches of the control room roof in the vicinity of the control room
ventilation system air in-takes. It was also noted that six 8,000-scf
nitrogen tanks were located
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April 27, 1989
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in the vicinity of the control room air intakes. Nitrogen leakage and
dispersion into the air intakes may lead to incapacitation of the control
room operators.
2. A detonation of a hydrogen storage tank (energy equivalent to 217 pounds
of TNT) may structurally damage and affect performance of safety-related
equipment on the control room roof such as the ventilation system intake
and exhaust structure, the emergency pressurization system, and equipment
in the control room itself.
3. An explosion of the hydrogen delivery truck that provides hydrogen to the
facility through a fill line located at ground level on the wall of the
auxiliary building may structurally damage safety-related component
cooling water pumps and radwaste storage tanks located inside the
auxiliary building and in the vicinity of the hydrogen fill line.
Discussion:
The topical report "Guidelines for Permanent BWR Hydrogen Water Chemistry
Installations," 1987 Revision, EPRI NP-5283-SR-A was reviewed and accepted
by NRC. NRC's approval letter, dated July 13, 1987, states that this topical
report may be useful in providing industry guidance for the design, operation,
maintenance, surveillance, and testing of hydrogen systems for (1) providing
a cover gas in the PWR volume control tank and (2) for cooling the main
turbine generator. In addition, Information Notice No. 87-20, "Hydrogen
Leak In Auxiliary Building," dated April 20, 1987, indicated that the NRC was
then reviewing the EPRI/BWROG topical report (EPRI NP-5283-SR-A). The Trojan
plant hydrogen facility does not meet these guidelines from the standpoint of
(1) the separation distance needed between a hydrogen pipe break and the
control room ventilation intake to prevent buildup of a flammable or explosive
gas mixture inside the control room, and (2) the separation distance needed to
prevent damage to safety-related structures resulting from the explosion of an
8,000-scf hydrogen tank.
Related Generic Communications:
Information Notice No. 87-20, "Hydrogen Leak In Auxiliary Building," dated
April 20, 1987, discusses leakage of hydrogen from a volume control tank globe
valve in the auxiliary building.
NUREG/CR-3551, ORNL/NOAC-214 "Safety Implications Associated With In-Plant
Pressurized Gas Storage and Distribution Systems in Nuclear Power Plants,"
dated May 1985, provides information useful in considering hazards and methods
to ensure the safe handling of pressurized gases, including hydrogen.
EPRI NP-5283-SR-A, "Guidelines For Permanent BWR Hydrogen Water Chemistry
Installations" - 1987 Revision, dated September 1987, is a topical report
approved by the NRC that provides industry guidance for the design, operation,
maintenance, surveillance, and testing of hydrogen systems. It was also recom-
mended by the NRC for use on hydrogen systems for (1) providing a cover gas in
the PWR volume control tank, and (2) for cooling the main turbine generator.
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April 27, 1989
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No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical
contact listed below or the Regional Administrator of the appropriate regional
office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact: Frank J. Witt, NRR
(301) 492-0823
Attachment: List of Recently Issued NRC Information Notices
. Attachment
IN 89-44
April 27, 1989
Page 1 of 1
LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
_____________________________________________________________________________
Information Date of
Notice No._____Subject_______________________Issuance_______Issued to________
88-82, Torus Shells with Corrosion 5/2/89 All holders of OLs
Supp. 1 and Degraded Coatings in or CPs for BWRs.
BWR Containments
89-43 Permanent Deformation of 5/1/89 All holders of OLs
Torque Switch Helical or CPs for nuclear
Springs in Limitorque power reactors.
SMA-Type Motor Operators
88-97, Potentially Substandard 4/28/89 All holders of OLs
Supp. 1 Valve Replacement Parts or CPs for nuclear
power reactors.
89-42 Failure of Rosemount 4/21/89 All holders of OLs
Models 1153 and 1154 or CPs for nuclear
Transmitters power reactors.
89-41 Operator Response to 4/20/89 All holders of OLs
Pressurization of Low- or CPs for nuclear
Pressure Interfacing power reactors.
Systems
88-75, Disabling of Diesel 4/17/89 All holders of OLs
Supplement 1 Generator Output Circuit or CPs for nuclear
Breakers by Anti-Pump power reactors.
Circuitry
89-40 Unsatisfactory Operator Test 4/14/89 All holders of OLs
Results and Their Effect on or CPs for nuclear
the Requalification Program power reactors.
89-39 List of Parties Excluded 4/5/89 All holders of OLs
from Federal Procurement or CPs for nuclear
or Non-Procurement Programs power reactors.
89-38 Atmospheric Dump Valve 4/5/89 All holders of OLs
Failures at Palo Verde or CPs for nuclear
Units 1, 2, and 3 power reactors.
_____________________________________________________________________________
OL = Operating License
CP = Construction Permit
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