ML20129E729

Safety Evaluation Supporting Amend 175 to License NPF-6

ML20129E729
Person / Time
Site:	Arkansas Nuclear
Issue date:	09/26/1996
From:	NRC (Affiliation Not Assigned)
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Shared Package
ML20129E670	List: ML20129E665 ML20129E729
References
NUDOCS 9610010150
Download: ML20129E729 (6)

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UNITED STATES 3

NUCLEAR REGULATORY COMMISSION

'I WASHINGTON, D.C. 30666 4 00?

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h SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.T75 TO FACILITY OPERATING LICENSE NO. NPF-6 ENTERGY OPERATIONS. INC.

1 ARKANSAS NUCLEAR ONE. UNIT NO. 2 DOCKET NO. 50-368

1.0 INTRODUCTION

i 1By letter dated April 4, 1995, Entergy Operations, Inc., the licensee for i

Arkansas Nuclear One, Unit 2 (ANO-2), requested revisions to Technical Specification (TS) 3.6.1.3 " Containment Air Locks" to allow entry and exit of 4

the containment air locks to perform maintenance on air lock components. The i

amendment would also provide an action statement for an inoperable air lock interlock and make other changes consistent with NUREG-1432, " Standard i

Technical Specifications", Rev. O. for Combustion Engineering Plants.

i This submittal was revised by letters dated April 25 and August 19, 1996, in response to staff comments and a request for additional information.

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revisions included changes to the TSs and the Bases section. These revisions did not change the initial no significant hazards consideration determination.

2.0 BACKGROUND

The ANO-2 containment building is equipped with two personnel air locks. One for normal ingress and egress is located at the 386 foot elevation at approximately 135 degrees. The second is the emergency escape hatch located at the 354 foot elevation at approximately 315 degrees.

Each air lock is equipped with two doors, each capable of withstanding the design basis accident (DBA) peak pressure (P, as defined in 10 CFR Part 50, Appendix J) of 54 psig, The air lock doors are designed to open into the containment building such that the initial pressurization will force the door into the seat to maximize the sealing force.

Each door is sealed by concentric elastomeric seal rings and is provided with a fitting for pressure testing between these seals.

Each door is provided with dogging devices which can be installed as necessary to facilitate leakage rate testing.

These dogging devices simulate the-force that would be exerted on the door seals by the containment accident pressure.

The doors are controlled by a mechanical interlock which prevents simultaneous opening of both doors.

The licensee has proposed revising the containment air lock TSs to more closely resemble the improved standard TSs for Combustion Engineering plants in order to gain more flexibility in testing and response to abnormal situations.

These specifications, as described in SECY 93-067, " Final Policy 9610010150 960926 PDR ADOCK 05000368 p_

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. Statement on Technical Specifications' Improvements" represent the result of detailed reviews and discussions with the industry to derive TSs which can improve operational safety and efficiency. They frequently serve, as in this review, as a model for plant specific TSs changes.

3.0 EVALUATION Each of the proposals made by the licensee is discussed below along with the staff evaluation.

3.1 Relocate TS 3.6.1.3.b from the limiting condition for operation (LCO) section of the TSs to the surveillance requirements section.

The current ANO-2 TS 3.6.1.3.b states that each containment air lock shall be OPERABLE with an overall air lock leakage rate of 0.05 L, at P,.

The licensee is proposing to relocate this statement to the surveillance requirements section of the TSs (4.6.1.3.1.b) as an administrative enhancement. This change is consistent with NUREG-1432 and only administrative 1y changes the TSs. The staff finds this change acceptable.

3.2 Expand the scope of Action Statement 3.6.1.3.a to include actions to be taken with one inoperable door in one or both air locks.

j The present action statement does not take into consideration that ANO-2 has a two air lock containment structure with each door in each air lock rated to withstand full design pressure. Since each door is rated to full design pressure, containment integrity is assured with one operable door in each air lock.

The licensee has added Footnote 2 to page 3/4 6-4 which states that with both j

air locks inoperable, entry and exit is permissible for 7 days under administrative controls.

The Bases for this statement in NUREG-1432 restrict the reasons for entry under these conditions to containment entries on a periodic basis to perform TSs surveillances and required actions, as well as other activities on equipment that support TSs-required equipment.

Other activities may be performed (that is, non-TSs activities) if the containment is entered, using the inoperable air lock, to perform an allowed activity listed above. The licensee expanded these criteria, based on approved TSs for another facility, to permit containment entry through an inoperable door if it is necessary to perform repairs on equipment which might otherwise cause a reactor transient or trip.

This change is consistent with NUREG-1432 and provides a reasonable balance between plant safety and containment integrity.

The staff finds this change l

acceptable.

i 3.3 Revise LC0 3.6.1.3 to allow air lock entry and exit for maintenance of air lock components.

Section 3.6.1.3.a.1 of the ANO-2 TSs require that should one containment air lock door become inoperable, the operable door would be shut and locked if the l

inoperable door cannot be restored to an operable condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Should any component other than the inner door render the air lock inoperable, the inner door can be locked to comply with the specification. This maintains accessibility to the outer door, and other air lock components, for repair to

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allow the restoration of air lock operability. Should the inner air lock door become inoperable, the outer door is required to be locked within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 4

with no provision for unlocking it for any reason. This effectively renders inner door maintenance impossible without a containment entry, at power, through the other air lock.

The practice of gaining access to perform maintenance on an inoperable inner door via the other air lock would result in an unnecessary containment entry at power with the associated potential for radiation exposure and heat stress while transiting from one air lock to the other. The time necessary to have the operable outer door open, for ingress and egress necessary to facilitate air lock repairs, would be 2 or 3 minutes per trip. Even if a number of trips through the outer door were required, the combined open time would be much shorter than the current I hour allowable outage time specified in TS 3.6.1.1.

The licensee has therefore proposed a change to this LC0 to allow ingress and egress through the operable outer door in order to perform repairs on the inoperable inner door.

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This change is consistent with NUREG-1432. The Bases for this section of NUREG-1432 specify that the change is acceptable due to the short time which i

the operable door will be open.

The licensee has indicated that it would not maintain the operable door open any longer than necessary for entering and exiting the air lock. The Bases for NUREG-1432 also state that an operable air lock should be used for containment entry and exit "[i]f ALARA [as low as reasonably achievable] conditions exist." The licensee has indicated in the l

April 4,1995, submittal that ALARA conditions are not favorable when another air lock is used.

The staff therefore, finds the licensee's proposal acceptable.

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3.4 Action Statement 3.6.1.3.b has been added to address an inoperable air i

lock interlock mechanism.

The current ANO-2 TSs make no provision for an inoperable air lock interlock l

mechanism. An inoperable air lock interlock might make it possible to open both doors in an air lock simultaneously, thereby creating a breach in containment while containment integrity is required. Therefore, the licensee has proposed an action statement similar to that in NVREG-1432. Action Statement 3.6.1.3.b provides for verifying that at least one operable door is closed within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and locked closed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Entry and exit may be made through the air lock under the control of a dedicated individual who would perform the function of the interlock mechanism by ensuring that only one door at a time is opened.

In response to a staff question, the licensee specified that this individual would be a " capable individual who has been

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trained for the specific task." The individual would be stationed "in the immediate vicinity" of the air lock and have "no concurrent duties."

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l Based upon the fact that a trained, dedicated individual would be in the immediate vicinity of the air lock and would be capable of maintaining the, i

safety function of the interlock, and the fact that the proposed change is in accordance with NUREG-1432, the staff finds the proposed change cceeptable.

l 3.5 The licensee has proposed removing the action statement requirement to shut down the reactor when the next required overall air lock leakage test is to be performed and one containment air lock door is inoperable.

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There is no reason for requiring the reactor to shut down as long as the 2

operable air lock door remains closed since each operable air lock door is capable of withstanding full design pressure. NUREG-1432 contains no such I

requirement. Consistent with NUREG-1432, entry and exit through the inoperable air lock would be permitted on the basis of the relatively short time that the operable door would be open and ALARA concerns in using the i

other air lock as discussed in the licensee's April 4,1995, submittal.

Therefore, the staff finds this change acceptable.

j 3.6 Revise the surveillance requirements for air lock door seal leakage rate testing by removing specific acceptance criteria and test methodologies i

and substituting references to 10 CFR Part 50, Appendix J.

The current ANO-2 Surveillance Requirement 4.6.1.3 stipulates the specific leakage rate test methodologies to be used and acceptable values necessary to satisfy the operability requirements for a containment air lock.

Revising this surveillance requirement to refer to 10 CFR Part 50, Appendix J will preclude the necessity for future amendments based solely on changes to i

Appendix J.

This change.is administrative in nature since the information being removed is duplicative to the requirements of 10 CFR Part 50, Appendix J.

This change is also consistent with NUREG-1432 and is therefore 3

acceptable.

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'3.7 Revise the air lock door seal minimum test pressure from 54 psig (P,) to 10 psig and the allowable leakage rate from 175 standard cubic centimeters (scca) to 0.Oll,.

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'ANO-2 TSs currently require air lock door seal leakage rate tests to be performed after each door opening, at P, which is 54 psig. The door seal test is intended to be a gross test to verify that the door seals were not damaged during the opening and closing cycles. This test does not replace the required overall barrel leakage test. The licensee has requested to change 4

this test pressure to 10 psig because performing the door seal test at a reduced pressure may allow the test to be performed without installing the mechanical dogs. As discussed in the licensee's April 4, 1995, submittal, the o

air lock vendor suggests a pressure of 3 psig as sufficient to meet this test requirement. The licensee has selected a test pressure of 10 psig to be consistent with NUREG-1432. The staff finds this acceptable.

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. The licensee also proposed changing the air lock door seal leakage criterion from 175 sccm to 0.0ll (0.0ll is the value used in NUREG-1432).

L for ANO-2 is the containme,nt leaka,ge rate equal to 0.1% of the containme,nt free air mass in the containment building at P which leaks from containment in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (approximately 162,895 secm). Although changing the acceptable door seal leakage rate from 175 seca to 0.01 L is a relaxation in the surveillance requirement acceptance criterion, it is a,cceptable due to the relatively small contribution to the overall allowable integrated containment leakage rate.

The staff therefore finds this change acceptable.

3.8 Remove current Surveillance Requirement 4.6.1.3.a.

Appendix J originally required,that an air lock door seal test be performed after every opening. The ANO-2 current Surveillance Requirement 4.6.1.3.a provides an exception to this requirement to allow the flexibility not to perform an air lock door seal test after each opening when the air lock is being used for multiple entries. The licensee has stated that this exemption is no longer necessary.

The exemption is no longer applicable because the regulation for which the exemption was issued was revised on September 22, 1980 (45 FR 62789) and the flexibility to not perform a door seal test after every opening was incorporated. The staff agrees that the exemption is no longer applicable and the deletion of Surveillance Requirement 4.6.1.3.a is acceptable.

3.9 The licensee has proposed a note for the containment air lock surveillance requirements which states:

"An inoperable air lock door i

does not invalidate the previous successful performance of the overall air lock leakage test."

This note is consistent with NUREG-1432. The Bases of NUREG-1432 state that i

this note is reasonable since either air lock door is capable of providing a i

fission product barrier in the event of a DBA.

The staff finds this acceptable for AN0-2.

3.10 The licensee has proposed new action statements when one or more air locks are inoperable for reasons other than those addressed in Action Statements 3.6.1.3.a or 3.6.1.3.b.

With one or more air locks inoperable for reasons other than those of 3.6.1.3.a or 3.6.1.3.b, the TSs will require that the licensee immediately initiate an evaluation of overall containment leakage per LC0 3.6.1.2.

Within I hour, at least one door in the affected air lock must be closed and the affected air lock must be restored to operable status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Otherwise, the unit must be in hot standby and then cold shutdown within the specified time. These actions are in accordance with NUREG-1432.

The actions are reasonable for ANO-2 and the corresponding action times are also reasonable. The staff finds this change acceptable.

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' 3.11 Addition of a clarification to the Bases of what constitutes an air lock door.

The licensee proposed adding a statement to the Bases that "the vertical end plates of the air lock barrel, on which the doors themselves are mounted, shall be considered part of the door." This clarifies the definition of an air lock door as either of the vertical ends of the right circular cylinder that forms the containment air lock. This definition is meant to assure that the appropriate action is taken (e.g., closure of the correct air lack door) in the case that a fault occurs on the stationary part of the door as well as the movable portion.

The staff finds this change acceptable.

4.0 STATE LONSULTATION In accordanes with the Comission's regulations, the Arkansas State official was notified of the proposed issuance of the amendment. The State official had no coments.

5.0 ENVIRONMENTAL CONSIDERAT M The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. The NRC staff has determined that the amendment involves 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 pro-posed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (60 FR 39438). Accordingly, the amendment meets the eligibility criteria for i

categorical exclusion set forth in 10 CFR 51.22(c)(9).

Pursuant to 10 CFR l

51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

6.0 CONCLUS M f

The Comission has concluded, based on the considerations discussed above,

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that:

(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner,. (2) such activities will be conducted in compliance with the Commission's regulations, and O) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

2 Principal Contributors:

R. Lobel J. Kennedy Date: September 26, 1996