ML20086B420

Proposed Tech Specs,Allowing Containment Personnel Airlock Doors to Be Open During Fuel Movement & Core Alterations

ML20086B420
Person / Time
Site:	Sequoyah
Issue date:	06/29/1995
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML20086B418	List: ML20086B416 ML20086B420
References
NUDOCS 9507050371
Download: ML20086B420 (15)

Text

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- ENCLOSURE 1 PROPOSED TECHNICAL SPECIFICATION (TS) CHANGE -

SEQUOYAH NUCLEAR PLANT (SON) UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328 (TVA-SON-TS-95-14)

LIST OF AFFECTED PAGES Unit 1 3/4 9-4 8 3/4 9-1 Unit 2 3/4 9-5 B 3/4 9-1 l

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9507050371 950629 PDR ADOCK 05000327 P- PDR. v;.

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n' REFUELING OPERATIONS 3/4.9.4 CONTAINMENT BUILDING PENETRATIONS LIMITING CONDITION FOR OPERATION 3.9.4 The containment building penetrations shall be in the.following status: l

a. The equipment door closed and held in place by a minimum of four bolts, 4~

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b. A minimum of one door in each airlock is closed,[and t

ci Each penetration providing direct access from the containment atmosphere to the outside atmosphere shall be either: j

1. Closed by an isolation valve, blind flange, or manual valve, or

2. Be capable of being closed by an OPERABLE automatic Containment Ventilation isolation valve.

APPLICABILITY: During CORE ALTERATIONS or movement of irradiated fuel within >

the containment. "

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i ACTION:

With the requirements of the above specification not satisfied, immediately. I suspend all operations involving CORE ALTERATIONS or movement of irradiated fuel in the containment building. The provisions of Specification 3.0.3 are not applicable. j t

SURVEILLANCE REQUIREMENTS ,A 4.9.4 Each of the above requiredecontainment building penetrations shall be determined to be either in its Iclosed/isputodi condition or capable of being closed by an OPERABLE automatic Containment Ventilation isolation valvelA triA  :

L/oujroursArioryto try 'staryot And jt ip6 m once per 7 days during CORE  :

ALTIRATIONS or movement of irra'diated fuel in the containment building by:

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a. Verifying the penetrations are in their IcMse#/iAlptedl SE@ dKb  !

condition, or l

-b. Testing the Containment Ventilation isolation valves per the applicable g, portions of Specification 4.6.3.2.

^ a MAR 251982 1 l

SEQUOYAH - UNIT 1 3/4 9-4 Amendment Nu. 12 j

3/4.9' REFUELING OPERATIONS BASES i

I 3/4.9.1- BORON CONCENTRATION The limitations on reactivity conditions during REFUELING ensure that:

1) the reactor will remain subcritical during CORE ALTERATIONS, and 2) a uniform boron concentration is maintained for reactivity control in the water' volume having direct access to the' reactor vessel. Maintaining the listed valves in the closed position precludes an uncontrolled boron dilution accident .

by closing the flow paths for possible~ sources of unborated water. These ]

limitations are consistent with the initial conditions assumed for the boron dilution incident in the accident analyses, j 3/4.9.2 INSTRUMENT.ATION The OPERABILITY of the source range neutron flux monitors ensures that redundant monitoring capability is available to detect changes in

, the reactivity condition of the core.

3/4.9.3 DECAY TIME.

The minimum requirement for reactor subcriticality' prior to movement of  ;

irradiated fuel assemblies in the reactor pressure vessel ensures that sufficient  ;

time has elapsed to allow the radioactive decay of the short lived fission  ;

products. .This decay time is consistent with the assumptions used in the accident analyses.

3/4.9.4 CONTAINMENT BUILDING PENETRATIONS The requirements on containment building penetration closure and OPERABILITY ensure that a release of radioactive material within containment will be I restricted from leakage to the environment. The OPERABILITY and closure restrictions are sufficient to restrict radioactive material release from a  !

fuel element rupture based upon the lack of containment pressurization potential while in the REFUELING MODE.

farr/_r- d 3/4.9.5 COMMUNICATIONS  ;

E The requirement for communications capability ensures that refueling  :

station personnel can be promptly informed of significant changes in the facility status or core reactivity conditions during CORE ALTERATIONS.

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SEQUOYAH - UNIT 1 B 3/4 9-1

INSERT A or both doors of both containment personnel airlocks may be open if:

1. One personnel airlock door in each airlock is capable of closure, and

2. . One train of the Auxiliary Building Gas Treatment System is OPERABLE in accordance with Technical Specification 3.9.12, i.

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-l Both sets of the containment personnel airlock doors may be open during movement  !

of irradiated fuel in containment and during core alterations provided one train of  :

Auxiliary Building Gas Treatment System (ABGTS)is available for manual operation.

The basis of this is that SON is analyzed for a fuel handling accident (FHA) in either the containment or the auxiliary building;, however, a manual ABGTS start may be i necessary for a containment FHA. The requirement for an airlock door to be capable of closure is provided to allow for long-term recovery from a FHA in containment.

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. 1 REFUELING OPERATIONS j 3/4.9.4 CONTAINMENT BUILDING PENETRATIONS LIMITING CONDITION FOR OPERATION 3.9.4 The containment building penetrations shall be in the following status:

a. The equipment door closed and held in place by a minimum of four bolts, ,

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b. A minimum of one door in each airlock is closed, and

c. Each penetration providing direct access from the containment atmosphere to the outside atmosphere shall be either:

1. Closed by an isolation valve, blind flange, or manual valve, or

2. Be capable of being closed by an OPERABLE automatic Containment Ventilation isolation valve.

APPLICABILITY: During CORE ALTERATIONS or movement of irradiated fuel within the containment.

ACTION:

s .. With the requirements of the above specification not satisfied, immediately suspend all operations involving CORE ALTERATIONS or movement of irradiated fuel in the containment building. The provisions of Specification 3.0.3 are not applicable.

SURVEILLANCE RE0VIREMENTS ,-m

/&C QaAKO 4.9.4 Each of the above required _ ontainment building penetrations shall be determined to be either in its closed /iM51ai4dl condition or capable of being einud bv an OPERABLE automatic Containment' Ventilation isolation valve (w/t hM Win >fourt orMr t( tb( stapf of 16d at' least once per 7 days during CORE ALTERATIONS or movement of i'rradiated fuel in the containment building by:

a. Verifying the penetrations are in their hfosed/i/ola[ed gpge condition, or

b. Testing the Containment Ventilation isolation valves per the applicable portions of Specification 4.6.3.2.

v SEQUOYAH - UNIT 2 3/4 9-5

3/4.9 ' REFUELING OPERATIONS l l

BASES 3/4.9.1 BORON CONCENTRATION The limitations on reactivity conditions during REFUELING ensure that:

1) the reactor will remain subtritical during CORE ALTERATIONS, and 2) a uniform boron concentration is maintained for reactivity control in the water volume having direct access to the reactor vessel. Maintaining the listed valves in the closed position pracludes an uncontrolled boron dilution accident by closing the flow paths for possible sources of unborated water. These limitations are consistent with the initial conditions assumed for the boron dilution incident in the accident analyses,.

l 3/4.9.2 INSTRUMENTATION The OPERABILITY of the source range neutron flux monitors ensures that redundant monitoring capability is available to detect changes in the reactivity j condition of the core.

3/4.9.3 DECAY TIME The minimum requirement for reactor subcriticality prior to movement of l irradiated fuel assemblies in the reactor pressure vessel ensures that sufficient time has elapsed to allow the radioactive decay of the short lived fission products. This decay time is consistent with the assumptions used in the accident analyses.

l 3/4.9.4 CONTAINMENT BUILDING PENETRATIONS The requirements on containment building penetration closure and OPERABILITY ensure that a release of radioactive material within containment.

will be restricted from leakage to the environment. The OPERABILITY and closure restrictions are sufficient to restrict radioactive material release from a fuel element rupture based upon ',he lack of containment pressurization potential while in the REFUELING MODE.

/HDEM ~$ t 3/4.9.5 COMMUNICATIONS The requirement for communications capability ensures that refueling station personnel can be promptly informed of significant changes in the facility status or core reactivity conditions during CORE ALTERATIONS.

SEQUOYAH - UNIT 2 B 3/4 9-1

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~lNSERT A or both doors of both containment personnel airlocks may be open if:

1. One personnel airlock door in each airlock is capable of closure, and

2. One train of the Auxiliary Building Gas Treatment System is OPERABLE in accordance with Technical Specification 3.9.12, INSERT B Both sets of the containment personnel airlock doors may be open during movement of irradiated fuel in containment and during core alterations provided one train of Auxiliary Building Gas Treatment System (ABGTS) is available for manual operation.

The basis of this is that SON is analyzed for a fuel handling accident (FHA) in either the containment or the auxiliary building:, however, a manual ABGTS start may be necessary for a containment FHA. The requirement for an airlock door to be capable of closure is provided to allow for long-term recovery from a FHA in containment.

1,: .-, t-ENCLOSURE 2 'j i

PROPOSED TECHNICAL SPECIFICATION (TS) CHANGE SEQUOYAH NUCLEAR PLANT (SON) UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328 l (TVA-SON-TS-95-14) i DESCRIPTION AND JUSTIFICATION FOR ALLOWING PERSONNEL AIRLOCK DOORS TO BE OPEN DURING CORE ALTERATIONS l

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Description of Chanae TVA proposes to modify the Sequoyah Nuclear Plant (SON) Units 1 and 2 technical specifications (TSs) by revising TS 3.9.4, Containment Building Penetrations, to allow for both sets of containment personnel airlock (PAL) doors to be open during core alterations and fuel movement. l Limiting Condition for Operation (LCO) 3.9.4.b will have administrative controls added that describe the conditions required to allow both sets of PAL doors to be open.

Surveillance Requirement (SR) 4.9.4 will have the wording, " closed / isolated" replaced with the word, " required." Additionally, the phrase "within 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> prior to the start of and at least" will be deleted. ,

i Bases Section B 3/4.9.4, Containment Building Penetrations, will have additional information added to describe the basis for allowing both sets of PAL doors to be  ;

open during core alterations and fuel movement, i

Reason for Chanae i Containment closure during core alterations and movement of irradiated fuel was  !

designed to limit offsite radioactive releases following a postulated fuel handling accident (FHA). However, other outage related work continues in containment during core alterations and movement of irradiated fuel. This requires numerous PAL door ,

manipulations as personnel enter and exit containment. The proposed changes would allow both PAL doors to remain open during core alterations and movement of irradiated fuel. This would reduce PAL door wear; therefore, increasing reliability.

The proposed changes would also facilitate scheduling and performance of outage related work during core alterations and movement of irradiated fuel.

Justification for Chanaes The SON design utilizes a secondary containment environment, which envelopes the i auxiliary building, including the refueling floor and spent fuel pit. Based upon  !

calculations, the design can additionally provide filtration coverage of one open l containment environment. Both units typically will not be in a refueling outage at the l same time. This secondary containment environment provides effluent filtering via the auxiliary building gas treatment system (ABGTS) to mitigate the effects of a postulated FHA occurring in the spent fuel pit (which is common to both units).

Further, TS 3.9.12, Auxiliary Building Gas Treatment System, requires one train of this system to be operable whenever there is irradiated fuel in the spent fuel pit. TS 3.7.8, Auxiliary Building Gas Treatment System, requires two trains to be operable for Modes 1 through 4. Thus, with one unit in operation, both trains of the ABGTS will normally be operable. Updated Final Safety Analysis Report (UFSAR) Chapter 6.2.3 describes the design capabilities of the ABGTS.

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i The SON design basis FHAs are defined as the dropping of a spent fuel assembly onto j the spent fuel pit floor or inside containment. Both analyses resulted in the rupture of j the cladding of all the fuel rods in the assembly. These FHA events are postulated for  ;

safety system design purposes even though many administrative controls and physical limitations are imposed on fuel handling operations. Chapter 15.5.6 of the SON UFSAR discusses the consequences of a postulated FHA analyzed for both the spent fuel pit area and inside containment with the PAL doors closed.

As discussed above, the FHA inside containment with the PAL doors closed, has been addrcssed in UFSAR Section 15.5.6. The results from this analysh shows an exclusion boundary dose of 70 roentgen equivalent man (REM). Correspondingly, the results for an FHA in the auxiliary building shows a exclusion boundary dose of less than 50 REM. The primary reason for the differences in the two analyses is the conservative considerations taken for a possible containment purge occurring at the same time as the FHA. If an FHA were to occur while a purge was in progress and the PAL doors open, some small additional release may occur from the auxiliary building general exhaust prior to ABGTS start. This smallincrease is bounded by the summation of the two existing analyses previously addressed and will not exceed the 10 CFR 100 offsite dose limit of 300 REM. The doses in this scenario will remain well below the 10 CFR 100 limits. Combining these postulated events is coruidered to be extremely conservative and not credible (Reference UFSAR Chapter 3.1.1, Single Failure Criteria) since an FHA would have to occur in the spent fuel pit and inside containment simultaneously. This slight increase is judged to not be significant and is further mitigated by the programmatic controls and net safety benefit discussed below. Further, the requirement to rr ain min a PAL door capable of closure will provide additional conservatism in the m at of an FHA inside containment. Note that if a purge is not in progress, the resulting dose analysis is expected to be similar to t the auxiliary building analysis results.

Programmatic controls are in place to assure that postaccident doses are minimized in the event of an FHA. Abnormal Operating Instruction (AOI) 29, Dropped or Damaged Fuel Assembly or Loss of Reactor Cavity Water, provides operator actions to mitigate an FHA. These actions include, but are not limited to the following: (1) announce over the public address system for all personnel to evacuate the containment building or the refueling floor in the auxiliary building depending on the location of the accident; and (2) check the containment purge or auxiliary building isolation radiation  ;

monitors, depending on the location of the accident and determine if a gas release has occurred. It is noted that the containment purge and spent fuel pit radiation monitors are TS instrumentation consisting of redundant safety circuitry that will generate an automatic containment ventilation isolation and an auxiliary building isolation (ABI),

respectively, upon the detection of radioisotopes. The auxiliary building vent monitor is safety related and will generate an ABI upon detection, but is not redundant.

However, AOI-29 currently requires manual start of the ABGTS as a subsequent operator action. AOI-29 will be revised to require initiation of the ABGTS as an immediate operator action to provide an ABl. In addition, AOI-29 will be revised to assure closure of the PAL door. Based upon the above programmatic controls, the present analyses, and using "as low as is reasonability achievable" practices, no further analysis is rnuired to demonstrate compliance with 10 CFR 100.

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3-The 10 CFR 50, Appendix A, General O ssign Criteria 19 analysis has been reviewed with respect to relaxing the containment PAL closure requirements. This review indicated that the large break loss-of-coolant accident (LOCA) analysis remains bounding for all design basis accidents resulting in operator dose because the source term is considerably larger for the LOCA, while the exposure pathways to the control building are the same for an FHA and a LOCA.

This TS change would also eliminate much of the cycling of the PAL doors associated with personnel access. As a result, the PAL door seals would receive less wear, improving containment leakage performance.

The proposed chance also serves to limit worker radiation doses in the event of an FHA inside containment by allowing unimpeded egress from the containment. With the current requirements and the expected size of the work crews, multiple exits through the PAL would be required to allow people to exit. Workers would be required to wait inside containment while successive groups of people exit through the i

PAL. The proposed change would eliminate the wait time associated with successive groups passing through the PAL.

SR 4.9.4 has been revised to change the wording from closed / isolated to the word required. This word' consistent with NUREG-1431 and is needed to facilitate the i proposed changes ( 3ed above. The deletion of the requirement to verify valve {

operability "within 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> . . ." is appropriate since the SR has to be performed l before entering the applicability of this LCO. Further verification is performed every seven days during periods of applicability. The "within 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />" verification is overly restrictive and adds no additional safetv benefit beyond the other verification requirements.

EnvironmentalImoact Evaluation The proposed change does not involve an unreviewed environmental question because operation of SON Units 1 ard 2 in accordance with this change would not: l

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Result in a significam merease in any adverse environmentalimpact previously

1. i evaluated in the Final Environmental Statement (FES) as modified by NRC's l testimony to the Atomic Safety and Licensing Board, supplements to the FES, environmentalimpact appraisals, or decisions of the Atomic Safety and Licensing Board.

2. Result in a significant change in effluents or power levels.

3. Result in matters not previously reviewed in the licensing basis for SON that may have a significant environmentalimpact.

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. s ENCLOSURE 3 PROPOSED TECHNICAL SPECIFICATION CHANGE l SEQUOYAH NUCLEAR PLANT (SON) UNITS 1 AND 2  ;

DOCKET NOS. 50-327 AND 50-328 j (TVA-SON-TS-95-14) - -

DETERMINATION OF NO SIGNIFICANT HAZARDS CONSIDERATION FOR PERSONNEL AIRLOCK OPEN DURING CORE ALTERATIONS i

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Significant H:zards Evtluation l TVA has evaluated the proposed technical specification (TS) change and has determined that it does not represent a significant hazards consideration based on criteria established in 10 CFR 50.92(c).' Operation of Sequoyah Nuclear Plant (SON) in accordance with the proposed amendment will not:

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1. Involve a significant increase in the probability or consequences of an accident previously evaluated.

i The proposed change to TS 3.9.4, Containment Building Penetrations, would  !

allow the containment personnel airlocks (PALS) to be open during fuel movement .

and core alteration. The PALS are not an initiator to any accident. The position of the PAL doors (open or closed) during fuel movement and core alterations has  !'

no affect on the proh, ability of any accident previously evaluated.

All doses from a fuel handling accident (FHA) for the proposed change remain  !

well below the 10 CFR 100 limits. The proposed change will reduce the dose to -

workers inside containment in the event of a FHA by allowing more rapid egress i from containment. The wear on the PAL doors will significantly be decreased; j therefore, increasing the reliability of the PAL doors in the event of an accident. ;

i Since the probability of a FHA is not affected by the airlock door positions, and the doses remain within acceptable limits, the proposed change does not involve  !

a significant increase in the probability or consequences of an accident previously evaluated.

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2. Create the possibility of a new or different kind of accident from any previously analyzed.  ;

As previously stated, the pat. doors are not accident initiators. The open PAL  ;

doors do not represent a significant change in the configuration of the plant; ,

therefore, does not create a new or different type of accident from any previously  ;

analyzed.

3. Involve a significant reduction in a margin of safety.  ;

The margin of safety provided for an FHA inside containment remains well below i the 10 CFR 100 limits. Therefore, this proposed change to allow the PAL doors to remain open during fuel movement or core alterations does not involve a  :

significant reduction in the margin of safety.

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