ML20076F564
| ML20076F564 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 11/29/1993 |
| From: | Dennis Morey SOUTHERN NUCLEAR OPERATING CO. |
| To: | Ebneter S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 9410170321 | |
| Download: ML20076F564 (5) | |
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4 P.2/6 INov 29 '93 03126PM NUCLEFR ENG & LIC
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- Soumern Nuclear Operatng Company i
Post Ceco Box 1295 Birmingham. Alannma 35201 Teleonome (205) 868 8131 Southem Nudear Operating Company o... uo,.y l
E.Te$,7 fne southem erectne system November 29, 1993 l
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Mr. S. D. Ebneter Regional Administrator, Region 11 U.S. Nuclear Regulatory Commission 101 Marietta Street, NW., Suite 2900 Atlanta, Georgia 30323 Joseph M. Farley - Unit 2 Raouest for Enforcement Discretion f
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Dear Mr. Ebneter:
It was recently determined that the Unit 2 B hydrogen recombiner was inoperable due to a failed component. Technical Specification 3.0.4 precludes changing modes unless the conditions of the Umiting Conditions for Operation are met without relying on the provisions contained in the action requirements. Technical Specification 3.6.4.2 requires that two hydrogen recombiners be operable. As a result, Farley Unit 2 is unable to enter Mode 2 without restoring the hydrogen recombiner to an operable status.
As discussed in the Attachment, it is requested that the NRC issue a Notice of Enforcement Discretion for Technical Specification 3.0.4 until both hydroger, recombiners are retumed to service or for a period of)0' days. It is requested that the Notice of Enforcement Discretion be issued as soon as possible as entry into Mode 2 is anticipated today.
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1 If there are any questions, please advise.
Respectfully submitted, Dave Morey Attachment cc:
Mr. B. L SleQel Mr. T. M. Ross U.S. Nuclear Regulatory Commission Document Control Desk l
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941o170321 931129
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PDR ADOCK 05000364 I
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s P.3.-6 to,V 29 '93 03227PM tUCLEr,R DG E LIC t
1 Request for Enforcement Olscretion l
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P.4/6 j
NOV 29 '93 03:27PM NUCLEAR ENG & LIC 1
Request for Enforcement Disemtion 1.
The Technical Specification for which enforcement discretion is requested.
Technical Specification 3.0.4 states," Entry into an OPERATIONAL MODE or other specified condition shall not be made unless the conditions of the Limiting _
i Condition for Operation are met without reliance on provisions contained in the ACTION requirements.'. Technical Specification 3.6.4.2 requires that two Independent containment hydrogen recombiner systems shall be operable for Modes 1 and 2. Enforcement discretion is requested for Technical Specificadon 3.0.4.
2.
Circumstances requiring prompt action.
Component failures in the 2B hydrogen recombiner discovered while in Mode 3 resulted in one of the two hydrogen recombiners becoming inoperable. Efforts to obtain parts to restore the recombiner have not been successful. As a result, Farley Unit 2 can not change modes in its efforts to startup following a refueling outage.
3.
Safety basis for the request for enforcement discretion.
I As stated in Farley_Technico Specification Bases B 3/4.6.4,"Elther recombiner I.'
unit (or the purge system)l! capable of controlling the expected hydrogen i
generation associated with 1) zirconium-water reactions,2) radiolytic decomposition of water, and 3) corrosion of metals within containment."
Consequently: a single recom0iner provides adequate hydrogen removal capability for Modes 1 or 2. Post-LOCA hydrogen concentration in the containment would not reach the lower flammability limit of 4.0 volume percent until about 30 days after the accident, assuming no recombiner in service end no j
venting of containment atmosphere.
As further evidence of the marginal safety benefit of the recombiners, the Farley l
Level 11 Probability Risk Analysis recently submitted to the NRC states that the peak containment pressure for the worst case hydrogen bum is less than the lower bound ultimate capacity of containment.
4.
Proposed compensatory measures.
A single recombiner provides adequate hydrogen removal capability, if both i
hydrogen recombiners become inoperable, operation will be in accordance with Technical Specification 3.0.3.
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I P.5/6 NOV 29 '93 03:28PM NUCLEM ENG & LIC -
5.
Justification for duration of the request for enforcement discretion.
Enforcement discretion is requested for a 30 day duration. the same as the action statement. If the inoperable hydrogen recombiner were discovered in Mode 1,30
' days would be allowed for repair Repair of the recombiner will be pursued on an expedited basis; however, repair parts are not immediately available.
6.
Significant safety hazards consideration.
Following a design basis accident, hydrogen gas may be generated inside containment by reactions such as zirconium metal with water, corrosion of j
materials of construction, and radiolytis of aqueous solution in the core and sump. To ensure that the hydrogen concentration is maintained at a safe level, i
hydrogen recombiners are provided, along with a backup post accident venting system. Consequently, loss of a single hydrogen recombiner will not create the possibility of a new or different kind of accident previously evaluated.
A single hydrogen recombiner meets the design criterion of maintaining a safe hydrogen concentration with conf.derable margin. A second unit provides a l
redundant system of equal capab!!!ty on a redundsnt power supply. Post-LOCA hydrogen concentration in the containment would not reach the lower flammability limit of 4.0 volume percent until about 30 days after the accident, assuming no recombiner in service and no venting of containment atmosphere._ Thirty days aBows adequate time for operator action to prevent hydrogen accumulation from exceeding the 4.0 volume percent flammability limit. Furthermore, the frequency drogen producing accidents for Farley Nuclear Plant is on the order of 6 x -
of hy/ year. As a result, operation with a single hydrogen recombiner wi 10'"
in a significant increase in the probability or consequences of an accident.
previously evaluated.
Since a hydrogen recombiner, the post accident venting system, and the post i
accident mixing system will be operable, there is not a significant reduction in a margin of safety.
in addition, the at ove pe:ition is consistent with NUREG-1431, Standard Techncial Specifications - Westinghouse Plants, dated September 1992, Bases 3.6.8, concerning the operability of the hydrogen recombiners, "...the provisions of LCO 3.0.4 are not applicable. As a result, a MODE change is allowed when one recombiner is inoperable. This allowance is based on the avaEmbElty of the other hydrogen recombiner, the smaN probability of a LOCA or SLB occumng (that would generste an amount of hydrogen that exceeds the flammabulty Imit),
and the amount of time available after a LOCA or SLB (should one occur) for operator action to prevent hydrogen accumulation from exceeding the '
flammability limit."
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P.6/6 NOV 29 '93 03:29PM NUCLEAR ENG & LIC 7.'
Consequences to the environment.
Changing modes with only one recombiner in service will not involve any significant change in the types of effluents that may be released offsite and no significant increase in the individual or cumulative occupational radiation exposure. Therefore, this request for enforcement discretion does notinvolve any irreversible environmental consequences.
8.
Review by Plant Operations Review Committee.
This request for enforcement discretion has been reviewed and approval has been recommended by the organization tasked to advise the General Manager-Nuclear Plant on all matters related to nuclear safety at Farley Nuclear Plant, i.e.,
the Plant Operations Review Committee.
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