ML20217R037

Requests Enforcement Discretion from Provisions of Tech Specs 3.0.3 as It Applies to Requirements of Tech Specs 3.7.8(b) & 3.3.2 to Maintain Three Independent Exhaust Booster Fans & Three Independent Main Exhaust Fans

ML20217R037
Person / Time
Site:	South Texas
Issue date:	05/01/1998
From:	Parkey G HOUSTON LIGHTING & POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9805130123
Download: ML20217R037 (10)

Text

.

1 Nuclear Operating Company EW E hr swth rauvnycesketre cowratusstairm et2 aazsr ass-wth. re,as77+s3

m. l May 1,1998 ST-NOC-AE-000154 STI 30610525 File No.: G20.02 G21.02 10CFR50.36 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 South Texas Project Unit 1 Docket No. STN 50-498 Request for Enforcement Discretion for Technical Specification 3.0.3 as It Anolies to Oncrability Reauirements for the Fuel Handline Buildine HVAC 1

STP Nuclear Operating Company (STPNOC) requests enforcement discretion from the provisions of Technical Specification 3.0.3 as it applies to the requirements of Technical l

Specifications 3.7.8(b) and 3.3.2 (Table 3.3-3, Functional Unit !1) to maintain three independent j Exhaust Booster Fans and three independent Main Exhaust Fans and required actuation l

instrumentation operable. Exhaust Booster Fan 11B has failed and must be replaced. The failed fan '

can be replaced within its 7 day allowed outage time. However, replacement of the fan will require ,

making the other two exhaust booster fans that share the common supply and exhaust plenums inoperable for the brief time needed to install and subsequently remove a temporary modification.  ;

Specifically, STPNOC requests discretion from the requirement to apply Specification 3.0.3 for the 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> required to install the temporary modification and for 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> required to remove the  ;

temporary modification so that repairs of FHB Exhaust Booster Fan 1iB can be completed.  ;

i The attached information is provided pursuant to the Nuclear Regulatory Commission guidance for requests for enforcement discretion.

If you should have any questions concerning this matter please contact either A. W. /'

/

Harrison at (512) 972-7298 or J. R. Lovell at (512) 972-7799. /

//

AWH/

^

,tj e

G. L. Parkey e oc/

Plant Manager, Unit 1

Attachment:

Information in Support of Requested Enforcement Discretion 9805130123 980501 PDR ADOCK 05000498 P PDR

r i: .

l NOC-AE-000154 I

File No.: G20.02 G21.02 Page 2 Ellis W. Merschoff Jon C. Wood Regional Administrator, Region IV Matthews & Branscomb '

U. S. Nuclear Regulatory Commission One Alamo Center 611 Ryan Plaza Drive, Suite 400 106 S. St. Mary's Street, Suite 700 Arlington, TX 76011-8064 San Antonio,TX 78205-3692 Thomas W. Alexion Institute of Nuclear Power Project Manager, Mail Code 13H3 Operations - Records Center U. S. Nuclear Regulatory Commission 700 Galleria Parkway Washington, DC 20555-0001 Atlanta, GA 30339-5957 David P. Loveless Richard A. Ratliff Sr. Resident Inspector Bureau of Radiation Centrol i

c/o U. S. Nuclear Regulatory Commission Texas Department of Health l P. O. Box 910 1100 West 49th Street l _ Bay City, TX 77404-0910 Austin, TX 78756-3189 J. R. Newman, Esquire D. G. Tees /R. L. Balcom Morgan, Lewis & Bockius Houston Lighting & Power Co.

1800 M. Street, N.W. P. O. Box 1700 I Washington, DC 20036-5869 Houston,TX 772.~1 M. T. Hardt/W. C. Gunst Central Power and Light Company City Public Service ATTN: G. E. Vaughn/C. A. Johnson P. O. Box 1771 P. O. Box 289, Mail Code: N5012 San Antonio,TX 78296 Wadsworth,TX 77483 l A. Ramirez/C. M. Canady City of Austin Electric Utility Department 721 Barton Springs Road Austin.TX 78704

e Attachment

., , ST-NOC-AE-000154 Page 1 of 10 Information in Support of Requested Enforcement Discretion

1) The Technical Specification or other license conditions that will be affected.

Technical Specifications 3.7.8 and 3.3.2 (Table 3.3-3, Functional Unit i1) require ihree independent Exhaust Booster Fans and three independent Maiu Exhaust Fans and actuation instrumentation to be operable. In addition, Technical Specification 3.9.12 establishes requirements for FHB HVAC during movement of fuel. No discretion with respect to Specification 3.9.12 is necessary since STPNOC will comply with the applicable action of this specification not to move fuel or operate the crane over the spent fuel pool. (See Ccmpensatory Actions in Item 6, below.)

Operability of the Fuel Handling Building Exhaust Air System (FHBEAS) ensures that radioactive material leaking from the Err 1ency Core Cooling (ECC) equipment within the FHB following a loss of coolant accident @OCA) and radioactive material release from an accident involving an irradiated assembly in the FHB are filtered prior to reaching the environment.

Replacement of failed exhaust booster fan 11B will require a temporary modification to isolate the ductwork to the fan from the rest of the systan. The process ofinstalling and subsequently removing the temporary modification will require breaching the common exhaust and supply plenums serving the three exhaust booster fans. During the time the plenums are breached, the requirements of Specification 3.7.8 for the FHB HVAC system are not met. In addition, while the modification is being installed and removed, the other exhaust booster fans and the main exhaust fans will be put in pull-to-lock for personnel safety. In this condition, the system cannot automatically actuate and the requirements of Specification 3.3.2, Table 3.3-3, Functional Unit 11 are not met for all trains. Both of these conditions would require that Technical Specification 3.0.3 be entered.

2) The circumstance surrounding the situation, includine root causes, the need for promDt action and identification of any relevant historical events.

FHB Exhaust Booster Fan IIB tripped at 0140 hours0.00162 days <br />0.0389 hours <br />2.314815e-4 weeks <br />5.327e-5 months <br /> on April 30,1998 while it was Ung r: stored from a surveillance test. Maintenance personnel determined that the motor o .is grounded and will have to be replaced. The inoperable fan placed STP Unit ! in the ACTION statement of Technical Specification 3.7.8, with 7 days to restore the fan or be in at least hot standby in the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and cold shutdown in the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

Prompt action is requested to approve the enforcement discretion to allow replacement work to proceed on the failed fan. Restoring FHB Exhaust Booster Fan i IB to an operable

9 Attachment

., , ST-NOC-AE-000154 Page 2 of 10 status will require removal and replacement of the motor. As described in Item 1 above, plans for replacement of the fan involve installation and subsequent removal of a temporary modification to isolate the duct to the failed fan from the common supply and exhaust plenums. STPNOC estimates the installation of the temporary modification will take no longer than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, and the removal of the temporary modification will take no longer than 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. STPNOC has scheduled the entire replacement evolution to be done well within the 7 day allowed outage time of a single failed fan. However, work to install the temporary modification cannot begin until the request for enforcement discretion is approved.

The NRC approved a very sirailar requested waiver of compliance for Exhaust Booster Fan 21C in August,1992. In that case, the NRC approved a waiver from the requirements of Specification 3.0.3 and denied a requested 3 day extension to the 7 day allowed outage time. l The replacement methodology and justification for this proposed enforcement discretion does not substantially differ from the 1992 case except that STPNOC is not requesting extension of the allowed outage time in this request.

The fan failed due to a ground on the motor, although the cause for the ground has not been determined. The current failure did not exhibit the same symptoms as the 1992 failure. In 1992, there were some precursor indications of potential failure whereas in this case no similar precursors were observed. It should be noted that the fan had a history of l satisfactory performance, and that these fans have generally provided satisfactory s :rvice. l There have been two failures of an exhaust booster fan since STP began operation. l STPNOC plans to send the failed fan motor off-site for evaluation.  !

3) The safety baris for the reauest. including an evaluation of the safety sinnificance and potential consecuences of the proposed course of action.

The purpose of the Fuel Handling Building HVAC System is to mitigate the consequences of a fuel handling accident as well as a Loss-of-Coolant Accident (LOCA) by limiting plant site boundary dose to within the guidelines of10CFR100. This is accomplished by routing exhaust air from the spent fuel pool and the remainder of the FHB through ESF filter units containing HEPA filters and iodine removal carbon filters if high levels of airborne radioactivity are detected in the exhaust air (auto.matically upon an SI signal). i i

The major components of the exhaust air subsystem are:

• Three main exhaust fans

• Three booster fans

• Two carbon filters

Attachment

., , ST-NOC-AE-000154 Page 3 of 10 The three 50-percent-capacity exhaust booster fans are of the vaneaxial type. Tine fans are of the direct-drive type with single-speed motors. Fan .notors are totally enclosed,  ;

air-cooled, and statically and dynamically balanced. I Normally, exhaust air bypasses the filter units and is exhausted directly to the plant main vent stack. Upon detection of high radiation or SI signal, exhaust air is routed through the filter units, the exhaust booster fans, and main exhaust air fans, and is then delivered to the plant main vent stack.

As noted above, only two accidents scenarios are relevant with regard to the FHB HVAC system. The Fuel Handling Accident will be precluded from occurring by ensuring that no loads will be carried over the Spent Fuel Pool and no movement ofirradiated fuel will take place during the time that the repair activities are occurring. The Large Break LOCA (LBLOCA), although clearly within the design basis of the plant,is a highly unlikely l occurrence. In the event that a LBLOCA were to occur, it would take a minimum of 16 minutes for the Refueling Water Storage Tank to empty and the Emergency Core Cooling system to go into the recirculation mode by taking suction from the containment sump. At that point in time it would be assumed that radiation leakage from the ECCS would occur that would require the FHB HVAC system to be functional.16 minutes is considered ample time to secure the work, restore the plenum and take the fans out of

- pull-to-lock and for the workers to exit the FHB. It should be noted that during the performance of the maintenance activities associated with the 1992 replacement that the plenum was easily restored.

In addition to the above, it should be noted that the Licensing Basis for the STP includes the Leak-Before- Break concept. This methodology has demonstrated that the deterministic LBLOCA is not a credible event arid that in fact any large pipe rupture of the Reactor Coolant System would be preceded by leakage that is detectable by Control Room personnel using instrumentation installed in the containment. The time between initiation of the leakage and the actual break would allow for additional time i.e., greater than 16 minutes, to restore the plenum and place the booster fans in the standby condition.

A qualitative risk assessment based on the proposed action has been performed. The LBLOCA is an unlikely event which contributes very little to Core Damage Frequency.

The probability that a LBLOCA would occur during the 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> requested is less than 0.2% of the annual probability of the LBLOCA. The probability that the compensatory actions would subsequently fail is also considered to be small, making the likelihood of any adverse consequences essentially not credible.

r i

Attachment l l

., ST-NOC-AE-000154 I Page 4 of 10 Based on the above, STPNOC believes that safety significance and potential l consequences of the proposed plan of action is extremely small.

l 4) The basis for the conclusion that the enforcement discretion is not a potential l detriment to the public health and safety and that neither an unreviewed safety l question nor a sienificant hazard considerations involved. I Determination of No Unreviewed Safety Question.  !

1. Does the change involve a increase in the probability of occurrence or the consequences of an accident or malfunction of equipment important to safety j previously evaluated in the Safety Analysis Report?  !

l The proposed change is to increase the allowable time specified in Technical 1 Specification 3.0.3 before a plant shutdown is required. No increase in the probability of an evaluated accident will occur due to this extension of a time l limit. The consequences of an accident also do not increase due to this change i

since the compensatory actions will be simple, straightforward, and well briefed I with all participants prior to starting this evolution. Closing an access door, i installing an 18 x 18 inch cover, and manually starting fans can be easily accomplished in the allowed time. In Modes 1 - 4 the purpose of the Fuel J j Handling Building Exhaust Air System is to filter ECCS radioactive leakage that  :

occurs during the recirculation phase. Recirculation phase will not occur prior to i 16 minutes after an accident. Following an accident, the reactor will be I l automatically tripped. The plant announcement of this fact and direct communications with the control room will provide sufficient notification to 2 inform the personnel to restore the plenum integrity. The 16 minutes prior to radioactive ECCS leakage occurring is adequate time to secure the work, ensure that the plenum integrity is restored and the FHB Main and Exhaust Booster Fans started and for the workers to exit the FHB.

2. Does the change involve a possibility for an accident or malfunction of a different type than any evaluated previously in the Safety Analysis Report?

Delaying the plant shutdown required by Technical Specification 3.0.3 does not have the potential to create a new or different kind of accident from any previously evaluated. The system will continue to respond as required by the design with the compensatory measures established to restore plenum integrity.

f Attachment

, ST-NOC-AF-000154 Page 5 of 10 i

! 3. Does the change involve a reduction in the margin of safety as defined in the basis for any Technical Speci0 cation?

l The delay in plant shutdown required by Technical Specification 3.0.3 will not result in a reduction in the margin of safety since the compensatory measures will restore the Fuel Handling Building Exhaust Air System prior to the time it is required to remove contaminants in the accident condition.

t

! The unreviewed safety question evaluation above considers that the NRC paviously reviewed and approved an almost identical request for replacement of exhaust booster pump 21C in 1992. The conditions described in Houston Lighting & Power Company's ,

request for waiver of compliance dated August 18,1992 (ST-HL-AE-4185) and approved i by the NRC in letter dated August 19,1992 (ST-AE-HL-93160) are substantially the same as those evaluated in this request for discretion. The cumulative discretion time requested in this application is 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> vs.16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> in the 1992 request.

Based on the above discussions and evaluations and the earlier NRC review and approval of a similar request, no Unreviewed Safety Question exists.

Determination of No Sige!ficant Hazard Considerations South Texas Project has considered the criteria for assessing the potential of creating an unreviewed safety question or a significant hazards consideration with the exercising of enforcement discretion. In evaluating if discretion in enforcement constitutes a significant hazard the criteria of 10CFR50.92(c) is discussed below

1. Does the change involve a significant increase in the probability or l

consequence of an accident previously evaluated?

The proposed change is to increase the allowable time specified in Technical Specification 3.0.3 before a plant shutdown is required. This change will not increase the probability of an evaluated accident. The consequences of an accident also do not increase due to this extension in allowable time limits since the compensatory actions will be simple, straightforward, and well briefed prior to starting this evolution. In Modes 1 - 4 the purpose of the Fuel Handling Building Exhaust Air System is to tilter ECCS radioactive leakage that occurs during the recirculation phase. Recirculatioa phase will not occur prior to 16 minutes after an accident. Following an accident, the reactor will be automatically tripped. The plant announcement of this fact will provide sufficient notification to inform the personnel to restore the plenum integrity. The 16 minutes prior to radioactive ECCS leakage occurring is adequate time to secure the work, ensure that the

1 t

l Attachment l

' ST-NOC-AE-000154 )

l Page 6 of 10 I 1

1 plenum integrity is restored and the FHB Main and Exhaust Booster Fans started and for the workers to exit the FHB.

2. Does the change create the possibility of a new or different kind of accident I from any accident previously evaluated?  !

Delaying the plant shutdown required by Technical Specification 3.0.3 does not have the potential to create a new or different kind of accident from any previously evaluated. The system will continue to respond as required by the design with the compensatory measures established to restore plenum integrity.

l

3. Does this change involve a significant reduction in a margin of safety? l The delay in plant shutdown required by Technical Specifications 3.0.3 will not result in a significant reduction in the margin of safety since the compensatory measures will restore the Fuel Handling Building Exhaust Air System prior to the l time it is required to remove contaminants in the accident condition.

Based on the above evaluation, no Significant Hazard exists.

Since there is no Unreviewed Safety Question or Significant Hazard associated with this fan replacement, there is no potential detriment to the public heath and safety as a result of this request.

l 5) The basis for the conclusion that the enforcement discretion will not involve adverse consequences to the environment.

The South Texas Project has reviewed the proposed Enfucement Discretion request and the l Nuclear Regulatog Commission Final Environmental Assessment for the South Texas l Project Units 1 and 2 and has concluded that pursuant to 10CFR51, there are no significant i

radiological or non-radiological impacts associated with the proposed Enforcement Discretion request.

! This proposed Enforcement Discretion has been evaluated against the criteria for and I

identification of licensing and regulatory actions requiring environmental assessment in accordance with 10CFR51.21. It has been determined that the proposed changes meet the criteria for categorical exclusion as provided for under 10CFR51.22(c)(9). The following is a discussion of how the proposed Enforcement Discretion meets the criteria for categorical exclusion.

I Attachment

, ST-NOC-AE-000154 Page 7 of 10 t

10CFR51.22(c)(9): Although the proposed change involves changes to requirements with I respect to installation or use of a facility component located within the restric'ed area; l

l (i) the proposed change involves no Significant Hazards Consideration (refer to the No Significant Hazards Consideration section of this Enforcement Discretion Request),

(ii) there is no significant change in the types or significant increase in the amounts of any effluent that may be released offsite since the proposed changes do not affect the generation of any radioactive effluent nor do they affect any of the permitted release paths, and (iii) there is no significant increase in individual or cumulative occupational radiation exposure.

Accordingly, the proposed change meets the eligibility criteria for categorical exclusion set forth in 10CFR51.22(c)(9). Based on the aforementioned and pursuant to 10CFR51.22(b),

no environmental assessment or environmental impact statement need be prepared.

6) Any proposed compensatory actions.

The following compensatory action will be taken:

1. Administrative controls will ensure that in the unlikely event that emergency operation is required, operators have adequate time to ensure that FHB Main and Exhaust Fan motors are manually sta1ed. The following defines the conditions where the Fuel Handling Building Exhtust Air System can be maintained available while the Fans are in the " Pull-to-Lock" position:

a) Prior to opening the FHB Exhaust Booster Fan common plenum access panels, Maintenance personnel will inform the Control Room of their intentions. This information will be noted in the Control Room Log. ,

b) Following the opening of the plenum access panels, Maintenance personnel will maintain a watchstander at each opening who is in continuous communication with the Control Room.

L c) If at any time during this process, the Maintenance personne! are made aware, either via loudspeaker or radio, that a reactor trip has occurred, then the work will be secured, loose material removed, personnel will exit the plenums, and the access panels reinstalled as expeditiously as possible. The Control Room will conflum via

( continuous communication that the access panels have been reinstalled.

I

1 l

1 1

! Attachment

, , ST-NOC-AE-000154

) Page 8 of 10 d) Once confirmed that plenum integrity is restored, the Operator will manually  ;

j start the required FHB Main and Exhaust Booster Fans, or place them in automatic, I as required.

c) If at any time during this process, the Control Room notices an increase in Reactor Containment Building radioactivity that would be an indication of a Reactor Coolant System pressure boundary leak, Maintenance personnel will be informed to l secure the work, exit the plenums, and install the access panels as expeditiously as possible. Once confirmed that plenum integrity is restored, the Operator will manually start the required FHB Main and Exhaust Booster Fans or place them in l automatic as required. I i 2. During the repair of FHB Exhaust Booster Fan 1IB and the duration of the discretion, no  !

l irradiated fuel movement will occur and no loads will be moved over the Spent Fuel Pool. l

3. For the duration of the discretion, no activities will be conducted that could affect the level of the Spent Fuel Pool.

The above methodology is deemed acceptable since in Modes 1 - 4 the purpose of the Fuel Handling Building Exhaust Air System is to filter ECCS radioactive leakage that occurs during the recirculation phase. Recirculation phase will not occur prior to 16 minutes after an accident. Following an accident, the reactor will be automatically tripped. The plant announcement of this fact or radio communications will provide sufficient notification to inform the personnel to restore the plenum ir.tegrity. The 16 minutes prior to radioactive ECCS leakage occurring is adequate time to secure work, ensure that the plenum integrity is restored and the FHB Main and Exhaust Booster Fans staned, and for the workers to exit the FHB.

7) The lustification for it e duration of the enforcement discretion.

The duration for the requested enforcement discretion from the requirements of Specification 3.0.3 is 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> for the installation of the temporary modification and 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> for the removal of the temporary modification. These durations are reasonable and allow the maintenance personnel adequate time to perfomi their work safely with some margin.

8) A statement that the reauest has been approved by the Plant Operations Review Committee The South Texas Project Plant Operations Review Committee has reviewed the proposed Enforcement Discretion request and concurs with the content of this request.

Attachment

, ST-NOC-AE-000154 Page 9 of 10

9) Discussion of How the Applicable Notice of Enforcement Discretion Criterion for the Appropriate Plant Condition Specified in Section H is Satisfied The applicable Notice of Enforcement Discretion criteria for the subject request is to avoid undesirable transients as a result of forcing compliance with the license condition and, thus , ,

minimize potential safety consequences and operational risks or eliminate testing, I inspection, or system malignment that is inappropriate for the particular plant condition.

1 Since no fuel will be moved during the exhaust booster fan replacement evolution, the fuel handling accident is not credible and the only event for which the FHBEAS provides protection is the large break loss of coolant accident. The large break is an extremely low probability event and the durations for which the mitigation system will be unavailable are relatively small. In addition, the compensatory actions mitigate the technical inoperability of the FHB HVAC exhaust components and provide reasonable assurance that they can perform their design function in the unlikely event of an accident. Consequently,it is not appropriate to put the plant through a shutdown transient because a large break in the relatively short unavailability durations under consideration is not a credible event and the mitigation features are expected to function as required.

Follow up License Amendment Reauired

~

10)

No License Amendment will be required.

11) Statement that prior adoDtion of HDDroVed line. item imorovements to the Technical Specification or the Improved Technical Specification would not have Obviated the Need For the Notice of Enforcement Discretion Heauest The proposed Improved Technical Specifications for the South Texas Project have shutdown requirements similar to the current Technical Specifications for situations where all three exhaust booster fans are inoperable. Unlike current Technical Specifications, proposed ITS 3.7.12 Condition B allows for more than one exhaust train being inoperable such that entry into Spccification 3.0.3 would not be required. ITS Required Action B provides 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> to be in Mode 3 and may have provided sufficient time for installation of the temporay modification before a shutdown was required. However, whatever relief that may have been provided by ITS 3.7.12 is obviated by proposed ITS 3.3.8 for FHB HVAC Actuation Instrumentation. Required Action Bl.1 of that proposed specification would require that one train of exhaust filtration and two ventilaticn trains be placed in operation.

STPNOC is not aware of any line item improvements that would have provided relief from the condition.

l l

Attachment

, , ST-NOC-AE-000154 Page 10 of 10 i J

)

12) Any other information the NRC staff deems necessary before making a decision to exercise enforcement discretion. l 1

Considering the assessment performed in Items 3,4, and 9, STPNOC believes the proposed i enforcement discretion is overall beneficial to safety.

1 l

I

?

l l

l 1

)

lI