ML16138A589
| ML16138A589 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 04/30/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML16138A588 | List: |
| References | |
| NUDOCS 8705060236 | |
| Download: ML16138A589 (4) | |
Text
6A REG&
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 158 TO FACILITY OPERATING LICENSE NO. DPR-38 AMENDMENT NO. 158 TO FACILITY OPERATING LICENSE NO. DPR-47 AMENDMENT NO. 155 TO FACILITY OPERATING LICENSE NO. DPR-55 DUKE POWER COMPANY OCONEE NUCLEAR STATION, UNITS 1, 2, and 3 DOCKET NOS. 50-269, 50-270 AND 50-287 I. INTRODUCTION By letter dated February 12, 1986 as revised on October 10 and supplemented on October 20, 1986. Duke Power Company (the licensee) proposed changes to the Technical Specifications (TSs) of Facility Operating Licenses Nos. DPR-38, DPR-47 and DPR-55 for the Oconee Nuclear Station, Units 1, 2, and 3. These amendments would change the station's common TSs 3.16 and 4.4.3 to describe the operation and maintenance of the Containment Hydrogen Recombiner System (CHRS) which will serve as the primary method for maintaining hydrogen concentration in the post-accident containment atmosphere below the deflagration limit. The October 10, 1986 letter revised the February 12, 1986 application and submitted TS 4.4.3 which was rewritten and rearranged for clarity. The October 20, 1986 letter responded to our request for additional information.
II. DISCUSSION The Oconee Final Safety Analysis Report (FSAR) describes both purging and recombination as methods for controlling post-accident containment hydrogen concentrations. However, the CHRS is a preferable method of post-accident hydrogen control because it produces no radioactive gaseous release to the atmosphere.
The Hydrogen Purge System which presently contributes to hydrogen control will be available as a backup system, if needed. The licensee has indicated that the assignment of the primary control function to the CHRS will improve the safety of the plant because its capacity for handling containment gases is larger than that of the Hydrogen Purge System. Also, the resulting gases will be recirculated back to the containment after recombination, thus no radioactivity will be released to the atmosphere.
III. EVALUATION One of the requirements specified in 10 CFR 50.44(c)(3)(ii) "Standards for combustible gas control system in light-water cooled power reactors," of the hydrogen control rule is that plants with purge and repressurization systems 8705060236 870430 PDR ADOCK 05000269 P
-2 for hydrogen control following a loss of coolant accident (LOCA) must provide an internal recombiner or have the capability for installing an external recombiner following the start of an accident. The licensee chose the latter option and has capability for installing external recombiners in all of the Oconee units. A single recombiner will be shared by the three units.
Although the capability for hydrogen recombination is already implemented in the Oconee plant, the present TSs still identify the Hydrogen Purge Systems as the primary method for controlling post-accident hydrogen concentration.
Description of the Containment Hydrogen Recombiner System The licensee requested that TS 3.16 and 4.4.3 be changed to make hydrogen recombination the primary method for controlling hydrogen concentration in the containment after an accident and relegating containment purge as a backup mode of operation. The proposed TS changes are consistent with the standard TS. The recombiner used in the Oconee Nuclear Station is of a standard design - a thermal recombiner of a type presently used in several other plants. The recombiner itself and the power and control cabinet are mounted on two separate skids. The recombiner can be easily moved to the affected unit, anchored to its foundation and connected by flexible metal Dining to the Penetration Room Ventilation System (PRVS) piping which runs to and from the containment penetrations. The power and control cabinet will be locally mounted near the recombiners. The recombiner is designed to process 90 scfm of containment gases, however, because of significant pressure drops in the connecting ducts, its actual output will be lower, but will exceed 50 scfm.
This flow rate is higher than the operating flow rates in the Hydrogen Purge System. Recombination of hydrogen-air mixtures containing more than 0.5 v/o hydrogen can be made with 95% efficiency.
When connected to the PRVS piping, the recombiner will take the gases containing hydrogen from the containment building, recombine the hydrogen with oxygen from air, and return the resulting gas mixture back to the containment. In this way, no gases containing radioactivity will leave the containment building. All the piping and equipment associated with the recombiner system are designed to withstand a safe shutdown earthquake without a loss of function except for electric power which when interrupted can be manually restored using alternate power sources. Therefore, the design of the recombiner is suitable for performing its intended function.
Conclusion Based on the above considerations, the staff concludes that the assignment of the primary post-accident hydrogen control function to the CHRS and relegation of the Hydrogen Purge System as a backup meet the requirements of General Design Criterion (GDC) 41, "Containment atmosphere cleanup."
The staff further concludes that the proposed revision to TS 3.16 and 4.4.3 satisfactorily reflects this change in systems and is consistent.with the Standard Technical Specifications. The proposed revisions to the TSs also meet the requirements of GDC 42, "Inspection of Containment atmosphere cleanup systems," and GDC 43 "Testing of containment atmosphere cleanup systems" for inspection and testing of containment atmosphere cleanup systems. The staff, therefore, finds the change to the TS for hydrogen control to be acceptable.
-3 IV. ENVIRONMENTAL CONSIDERATION These amendments involve a change in the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. We have determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that these amendments involve no significant hazards consideration, and there has been no public comment on such finding.
Accordingly, these amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of these amendments.
V. CONCLUSION The Commission made a proposed determination that the amendments involve no significant hazards consideration which was published in the Federal Register (52 FR 5853) on February 26, 1987, and consulted with the state of South Carolina. No public comments were received, and the state of South Carolina did not have any comments.
We have concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health an&safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Dated: April 30, 1987 Principal Contributors: K. Parczewski H. Pastis
DATED:
April 30, 1987 AMENDMENT NO. 158 TO FACILITY OPERATING LICENSE DPR Oconee Nuclear Station, Unit 1 AMENDMENT NO. 158 TO FACILITY OPERATING LICENSE DPR Oconee Nuclear Station, Unit 2 AMENDMENT NO. 155 TO FACILITY OPERATING LICENSE DPR Oconee Nuclear Station, Unit 3 DISTRIBUTION:
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-NRC POR Local PDR PRC System NSIC PDII-3/DRP-I/II BJYoungblood R/F MDuncan HPastis LHarmon WJones TBarnhart (8)
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