United States Nuclear Regulatory Commission - Protecting People and the Environment

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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     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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                                                            Page 3 of 3


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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