ML20207S231

Safety Evaluation Re Generic Ltr 84-09 Re Hydrogen Recombiner Capability.Licensee Should Provide Nitrogen Containment Atmosphere Dilution Sys Capable of Isolating Air from Containment Whenever Isolation Signal Occurs

ML20207S231
Person / Time
Site:	Oyster Creek
Issue date:	03/13/1987
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20207S222	List: ML20207S221 ML20207S231
References
GL-84-09, GL-84-9, NUDOCS 8703190156
Download: ML20207S231 (4)

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO GENERIC LETTER 84-09 ON HYDROGEN RECOMBINER CAPABILITY GPU NUCLEAR CORPORATION l JERSEY CENTRAL POWER & LIGHT COMPANY OYSTER CREEK NUCLEAR GENERATING STATION DOCKET NO. 50-219

1.0 INTRODUCTION

The latest revision to the rule on combustible gas control,10 CFR 50.44, was issued on December 12, 1981. By the submittal dated September 24, 1985, the licensee submitted its justification that an inerted containment by itself was sufficient to control combustible gas concentrations inside I the containment after an accident. The licensee based its analysis on the generation rates contained in the BWR Owners Group Report NED0-22155. The staff has not approved these generation rates and continues to require that the generation rates in Regulatory Guide 1.7 be used to den'cnstrate compliance with the combustible gas control requirements of 10 CFR 50.44.

In order to satisfy requirements of 10 CFR 50.44, the licensee must rely on a hydrogen recombiner or an active pressurization and purge system in addition to the inerted containment. In 10 CFR 50.44(g), for Oyster Creek, 4 the combustible gas control systems are required to satisfy the design requirements of General Design Criteria 41, 42 and 43 of Appendix A to i 10 CFR Part 50.

l Additionally, the latest revision to the rule on combustible gas control requires licensees with plants that employ active pressurization and purge systems to demonstrate hydrogen recc6 1ner capability (10CFR50.44(c)(3)).

On May 8,1984, the staff completed an evaluation of the BWR Mark I Owners Group report which responded to the rule, and issued Generic Letter 84-09, "Recombiner Capability Requirements of 10 CFR 50.44(c)(3)(ii)." This letter provided three criteria by which licensees could determine whether hydrogen recombiner capability was required.

By letters dated August 2,1982; December 15, 1982; July 13, 1984; August 14, 1985; September 24, 1985, and June 16, 1986, Jersey Central Power & Light Company and GPU Nuclear (the licensees) provided information to demonstrate that Oyster Creek did not require an active combustible gas

. control system and therefore hydrogen recombiner capability to control combustible gases inside containment after an accident. Additional information was provided at meetings between the NRC staff and licensee staff on April 10, 1986.

G703190156 870313 9 DR ADOCK 0500

2 2.0 EVALUATION Generic Letter 84-09 allows the substitution of an active pressurization and purge system or a Nitrogen Containment Atmosphere Dilution System (NCAD) for hydrogen recombiners when all sources of oxygen except radiolysis are removed from the containment. In order to demonstrate compliance with the Generic Letter 84-09 oxygen source requirements, the licensee provided an assessment indicating that the only post-accident oxygen source would be due to radiolysis of the reactor coolant, and that such radiolysis wculd not produce sufficient oxygen to provide a post-accident combustible mixture inside the containment.

Based on the licensee's responses to Generic Letter 84-09, it is the staff's understanding that air is supplied to the containment instrument system during normal operation and that this air supply is automatically isolated whenever the primary isolation signal occurs for a Loss of CoolantAccident(LOCA). Once the air is isolated from the containment, a non-safety grade NCAD provides the working medium for the containment instrument system. Only one air operated valve is capable of automatically isolating the air supply from the containment. In attempting to justify not installing recombiners, the licensee is relying on one automatic valve to isolate air from the containment, and a non-safety grade NCAD to prevent combustible gas concentrations after a LOCA. It is our position that in addition to inerting the containment, an active combustible gas control system is needed. Furthermore, one isolation valve and a non-safety grade hCAD are insufficient to satisfy the criteria in Generic Letter 84-09. In order to satisfy the criteria in Generic Letter 84-09, the licensee should provide redundant automatic valves to isolate the air supply from the containment, and a redundant NCAD to control combustible gas concentrations (i.e., these automatic valves and the NCAD should meet therequirementsofGDC41,42and43asstatedin10CFR50.44(g)).

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An acceptable approach to demonstrate compliance with the criteria in Generic letter 84-09 is by the licensee comitting to the following

1. Modify the air supply system to provide redundant safety grade valves that automatically isolate air from the containment whenever a primary isolation signal occurs. Furtherrtore, provide operating procedures that require the air supply to be isolated whenever the containment oxygen concentration approaches 4 percent.

2. Provide a NCAD system that meets the GDC in 10 CFR 50.44(g) or the

! equivalent.

i 3. Provide a nitrogen supply for the instrumentation system that meets

! the GDC as stated in 10 CFR 50.44(g) or the equivalent and that l automatically supplies the instrument system upon receipt of a primary i containment isolation sional.

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4. For the NCAD system, the nitrogen supply tc the instrumentation

system and the redundant automatic valves that isolate the air from the containment, provide testing and surveillance Technical Specifications that limit the condition for operation upon the loss of redundancy.

5. The air supply valve to the TIP indexer must be periodically checked for position every 30 days, leak tested and provided with a Technical Specification to ensure reliability and availability.

6. Verify that the plant operating precedures were reviewed for consistency with the above requirements, and that ali cifferences were corrected in accordance with these changes. Furthermore, renove all procecures that advocate supplying air into the conteir. ment after receipt of the containment isolation signal.

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3.0 CONCLUSION

Based on our review of tre licensee's submittals, we conclude that the licensee should provide an NCAD capable of pressurizing the containment with nitrogen and redundant valves to automatically isolate air from containment whenever the primary isolation signal cccurs. These components should be designed to meet the requirements of GDC 41, 42 and 43. Alternatively, the licensee should install recombiner capability. This position is consistent with Generic Letter 84-09, and is necessary to demonstrate compliance with 10 CFR 50.44 for post-accident combustible gas control.

4.0 REFERENCES

1. Generic Letter 84-09. Recombiner Capability. Requirements of 10 CFR 50.44(c)(3)(ii), dated May 8, 1984.

2. Letter from P. B. Fiedler (GPUN) to Director, NRR, NRC, Final Rule on Interim Requirements Pelated to Hydrogen Control, dated August 2, 1982.

3. Letter D. M. Crutchfield (NRC) to P. B. Fiedler (GPUN) Recombiner Capability Requirements..., dated May 21, 1984.

4. l.etter from P. B. Fiedler (GPUN) to Director, NRR, NRC, Recorbiner Capability Requirements..., dated July 13, 1984.

5. Letter from P. B. Fiedler (GPUN) to J. A. Zwolinski (NRC) NRC Request for Additional Information..., dated August 14, 1985.

6. Letter from R. F. Wilson (CPUN) to J. A. Zwolinski (NRC), Containrent Vent and Purge System, dated September 24, 1985.

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7. Meeting on April 10, 1986, to discuss requested cancellation of the upgrade of the containment nitrogen purge / vent system, surmary dated September 15, 1986.

8. Letter from R. F. Wilson (GPUN) to J. A. Zwolinski (NRC),

Combustible Gas Control..., dated June 16, 1986.

9. Meeting on January 20, 1987, on combustible gas control.

Principal Contributor: P. Hearn Dated: March 13, 1987 l

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