ML20212F263
| ML20212F263 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 10/22/1997 |
| From: | Huffman W NRC (Affiliation Not Assigned) |
| To: | Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| References | |
| NUDOCS 9711040229 | |
| Download: ML20212F263 (3) | |
Text
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _
e October 22,:1997 Mr. Nicholas J. Liparulo, Manager Huclear-Safety and Regulatory Analysis Nuclear and Advanced Technology Division
. Westinghouse Electric Corporation
-P.O.-Box 355
.Pittsburgh, PA 15230
SUBJECT:
OPEN ITEMS ASSOCIATED WITH THE AP600 SAFETY EVALUATION REPORT (SER) l ON CONTAINMENT COMBUSTIBLE GAS CONTROL
Dear Mr,
Liparulo:
The Containment Systems and Severe Accident Branch of the U.S. Nuclear Regulatory Commission has provided an SER input to the Standardization Project Directorate on AP600 Combustible Gas Control, Final Safety Evaluation Report
-(FSER) Section 6.2.5.
The input has open items which have been extracted and designated as an FSER open items in the enclosure to this letter.
If you have any questions regarding this matter, you may contact me at (301) 415-1141.
Sincerely, original signed by:
William C. Huffman, Project Manager Standardization Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No.52-003
/
Enclosure:
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Mr. Nicholas J. Liparulo Docket No.52-003 Westinghouse Electric Corporation AP600 cc: Mr. B. A. McIntyre Mr. Russ Bell Advanced Plant Safety & Licensing Senior-Project Manager, Programs Westinghouse Electric Corporation Nuclear Energy Institute Energy Systems Business Unit 1776 I Street, NW P.O. Box 355 Suite 300 Pittsburgh, PA 15230 Washington, DC 20006-3706 Ms. Cindy L. Haag Ms. Lynn Connor Advanced Plant Safety & Licensing Doc-Search Associates Westinghouse Electric Corporation Post Office Box 34 Energy Systems Business Unit Cabin John, MD 20818 Box 355 Pittsburgh, PA 15230 Dr. Craig D. Sawyer, Manager Advanced Reactor Programs Mr. Sterling Franks GE Nuclear Energy U.S. Department of Energy 175 Curtner Avenue, MC-754 NE-50 San Jose, CA 95125 19901 Germantown Road Germantown, MD 20874 Mr. Robert H. Buchholz GE Nuclear Energy Mr. Frank A. Ross 175 Curtner Avenue, MC-781 U.S. Department of Energy, NE-42 San Jose, CA 95125 Office of LWR Safety and Technology 19901 Germantown Road Barton Z. Cowan, Esq.
Germantown, MD 20874 Eckert Seamans Cherin & Mellott 600 Grant Street 42nd Floor Mr. Charles Thompson, Nuclear Engineer Pittsburgh, PA 15219
- AP600 Certification NE-50 Mr. Ed Rodwell, Manager 19901 Germantown Road PWR Design Certification Germantown, MD 20874 Electric Power Research Institute 3412 Hillview Avenue Palo Alto, CA 94303
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SER OPEN ITEMS ASSOCIATED WITH AP600 FSER SECTION 6.2.5 480.1082F The AP600 uses safety-related Passive Autocatalytic Recombiners (FARs) to prevent the hydrogen concentration inside containment from reaching the flammability limit.
PARS use palladium or platinum as a catalyst to combine hydrogen and oxygen molecules into water vapor. One aspect of the use of PARS which has con-cerned the staff is the effect of potential chemical poisons on the operability of PARS. The environmental qualification of the PARS are performed in accordance with the specifications of Section 3.11 of the SSAR using the methodology defined in Appen-dix 3D of the SSAR.
In a letter, dated April 1, 1997, from Thomas T. Martin, to Nicholas tiparulo, titled, "AP600 Use of Passive Autocatalytic Recombiners (PARS) for Design Basis Hydrogen Control," the staff concluded that the chemical environment for environmental qualification should include potential poisons.
Westinghouse has cited an EPRI report on the effects of chemical poison on the performance of PARS to help substantiate the capa-bility of PARS in various reactor environments which may contain chemical poisons. However the staff still has a concern in this area.
In September 1980, operating BWRs in the United States were notified of several chemicals potentially present in the contain-ment atmosphere of BWRs, following a postulated LOCA, that may inhibit platinum / palladium alloys used to catalyze hydrogen. Two of the substances identified, phosphates and silicone oils, were not addressed in the EPRI poison report.
Some hydraulic systems in BWR containments have used phosphate esters and silicone oils as their working fluids. Westinghouse should address the possi-bility of these two poisons on the PARS hydrogen depletion analy-ses or provide a rationale why they would not be present in the containment atmosphere following a LOCA.
This is an FSER open item.
480.1083F AP600 employs a Hydrogen Concentration Monitoring Subsystem (HCMS) to monitor containment hydrogen concentration.
RG 1.97 endorses ANSI /ANS-4.5-1980, " Criteria for Accident Monitoring Functions in Light-Water-Cooled Reactors." Section 6.3.5.3 of the standard states that information display channel accuracy for the hydrogen monitor should be within plus or minus 10 percent of span.
The hydrogen analyzer relies on a heated platinum catalyst to func-tion. Similar to the staff's concerns about the effects of poison on the PARS, the catalytic efficiency of platinum in the hydrogen monitors can be reduced by as much as 25 percent by-certain chemical poisons. Westinghouse should consider the effect of poisons on the calibration and' accuracy of the HCMS due to the chemicals that may exist in the containment atmosphere following a postulated LOCA, or, provide assurance that the calibration of the instrument will be verified post accident. This is an FSER open item.
Enclosure