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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 8904260247 . IN 89-44 April 27, 1989 Page 2 of 3 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. . IN 89-44 April 27, 1989 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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