ML061630029

Exigent License Amendment Request Proposed One - Time Change to the Drywell Average Air Temperature Limit - Technical Specification 3.6.1.7

ML061630029
Person / Time
Site:	Limerick
Issue date:	06/09/2006
From:	Cowan P Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML061630029 (14)

Text

Exelon Nuclear 2 0 0 Exelon Way www.exeloncorp.com Nuclear Kennett Square, PA 19348 10 CFR 50.90 June 9,2006 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Limerick Generating Station, Unit 2 Facility Operating License No. NPF-85 NRC Docket No. 50-353

Subject:

Exigent License Amendment Request Proposed One-Time Change to the Drywell Average Air Temperature Limit - Technical Specification 3.6.1.7 Pursuant to 10 CFR 50.90, "Application for amendment of license or construction permit,"

Exelon Generation Company, LLC (Exelon), hereby requests a one-time change to the Technical Specifications (TS), Appendix A, of Facility Operating License No. NPF-85 for Limerick Generating Station (LGS), Unit 2.

The proposed one-time change would revise TS Limiting Condition for Operation (LCO) 3.6.1.7 concerning drywell average air temperature. Specifically, the proposed change would add a footnote to the TS limit for drywell average air temperature of 145 degrees Fahrenheit (OF) to allow continued operation of LGS, Unit 2, with drywell average air temperature no greater than 148°F for the remainder of the current operating cycle (Cycle 9),which is currently scheduled to end in March 2007, or until the next shutdown of sufficient duration to allow for unit cooler fan repairs, whichever comes first.

Currently, both fans of the 2D drywell unit cooler are inoperable and out of service, which resulted in an increase in drywell average air temperature from approximately 129°F to approximately 142°F. Plant action, to lower the chilled water supply temperature, has resulted in lowering the drywell average air temperature to approximately 140.5"F. Historically, LGS has experienced an increase in the drywell average air temperature of 2 - 4°F during the summer months with normal drywell air cooling system operation. Under the current plant condition, this could result in the potential to exceed the TS limit of 145°F. If the drywell average air temperature exceeds the TS limit of 145"F, TS 3.6.1.7 requires that the average air temperature be reduced to within the limit within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, or be in Hot Shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in Cold Shutdown within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Exigent License Amendment Request Drywell Average Air Temperature Limit One-Time Change Docket No. 50-353 June 9, 2006 Page 2 Noticing this license amendment request in the Biweekly Federal Register Notice for the standard 30-day public comment period would not expire until July, 2006. Therefore, the combination of the increase in the drywell average air temperature during the summer months and the standard regulatory process for noticing license amendment requests could result in an unwarranted plant shutdown. As a result, Exelon requests approval of the requested license amendment on an exigent basis in accordance with the requirements of 10 CFR 50.91(a)(6).

Exelon requests approval of the proposed amendment by July 7, 2006. Once approved, this amendment shall be implemented within 14 days of issuance.

At this time, Exelon is not requesting to increase the TS limit for the drywell average air temperature on a permanent basis for the following reasons. A review of the operating history for both the Unit 1 and Unit 2 drywell unit coolers has shown that both fans on a single unit cooler have not been out of service concurrently during normal plant operation. There have been several occasions when a single fan has been out of service. On those occasions, the redundant 100% capacity fan successfully operated and maintained the drywell average air temperature at normal operating conditions until the out-of-service fan was repaired and returned to service. Therefore, both fans being out of service at the same time during normal plant operation is considered to be an infrequent occurrence. In addition, there is insufficient time to completely re-evaluate the environmental qualification of structures, systems and components in the drywell for operating at the higher average air temperature on a permanent basis prior to reaching the summer months. to this letter provides the evaluation of the proposed change, including a discussion concerning the basis for exigent review by the NRC of this license amendment request. Attachment 2 provides the marked-up TS page indicating the proposed change.

The proposed TS change does not result in peak containment parameters exceeding their design values during a design basis accident. The proposed TS change is consistent with the design basis of electrical and mechanical structures, systems and components in the drywell.

The proposed TS change will not have an adverse effect on the qualified life for drywell components that are qualified in accordance with 10 CFR 50.49.

Exelon has concluded that the proposed change presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c).

There are no new regulatory commitments contained within this letter.

The proposed changes have been reviewed by the Plant Operations Review Committee and approved by the Nuclear Safety Review Board.

If you have any questions or require additional information, please contact Glenn Stewart at 610-765-5529.

Exigent License Amendment Request Drywell Average Air Temperature Limit One-Time Change Docket No. 50-353 June 9,2006 Page 3 A copy of this License Amendment Request, including the associated analysis regarding no significant hazards considerations, is being provided to the appropriate Pennsylvania State official in accordance with the requirements of 10 CFR 50.91(b)(l).

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 9th day of June, 2006.

Respecffully, Pamela 8.C&an Director, Licensing & Regulatory Affairs Exelon Generation Company, LLC Attachments:

1. Evaluation of the Proposed Change

2. Technical Specifications Markup Page cc: Regional Administrator - NRC Region I W/ attachments NRC Senior Resident Inspector - Limerick Generating Station I1 NRC Project Manager, NRR - Limerick Generating Station 11 Director, Bureau of Radiation Protection - Pennsylvania Department 11 of Environmental Protection

ATTACHMENT 1 Exigent License Amendment Request Limerick Generating Station, Unit 2 Docket No. 50-353 EVALUATION OF THE PROPOSED CHANGE

Subject:

Proposed One-Time Change to the Drywell Average Air Temperature Limit -

Technical Specification 3.6.1.7

7.0 REFERENCES

ATTACHMENT 1 EXIGENT LICENSE AMENDMENT REQUEST DOCKET NO. 50-353 EVALUATION OF THE PROPOSED CHANGE

1.0 DESCRIPTION

Pursuant to 10 CFR 50.90, Application for amendment of license or construction permit, Exelon Generation Company, LLC (Exelon), hereby requests a one-time change to the Technical Specifications (TS), Appendix A, of Facility Operating License No. NPF-85 for Limerick Generating Station (LGS), Unit 2.

The proposed one-time change would revise TS Limiting Condition for Operation (LCO) 3.6.1.7 concerning drywell average air temperature. Specifically, the proposed change would add a footnote to the TS limit for drywell average air temperature of 145 degrees Fahrenheit (°F) to allow continued operation of LGS, Unit 2, with drywell average air temperature no greater than 148°F for the remainder of the current operating cycle (Cycle 9), which is currently scheduled to end in March 2007, or until the next shutdown of sufficient duration to allow for unit cooler fan repairs, whichever comes first.

The proposed TS change does not result in peak containment parameters exceeding their design values during a design basis accident. The proposed TS change is consistent with the design basis of electrical and mechanical structures, systems and components (SSCs) in the drywell. The proposed TS change will not have an adverse effect on the qualified life for drywell components that are qualified in accordance with 10 CFR 50.49.

A description of the proposed change is provided in Section 2.0, "Proposed Change," of this Attachment. This attachment also contains a discussion concerning the requirements of 10 CFR 50.91(a)(6) regarding the basis for exigent review by the NRC of this license amendment request. Attachment 2 provides the marked-up TS page indicating the proposed change.

2.0 PROPOSED CHANGE

The proposed change revises LCO 3.6.1.7 concerning drywell average air temperature as described below.

The TS LCO 3.6.1.7 currently states:

3.6.1.7 Drywell average air temperature shall not exceed 145°F.

The proposed LCO states the following:

3.6.1.7 Drywell average air temperature shall not exceed 145°F**.

The following footnote is added:

• • Operation may continue with drywell average air temperature no greater than 148°F for the remainder of the current operating cycle (Cycle 9), or until the next shutdown of sufficient duration to allow for unit cooler fan repairs, whichever comes first.

The intent of the shutdown statement within the footnote is to allow for repair of both drywell unit cooler fans over the course of time to ensure sufficient redundancy and preclude a similar situation if only one fan is repaired and subsequently fails prior to the end of the current operating cycle.

Exigent License Amendment Request Attachment 1 Docket No. 50-353 Page 2 of 8 Evaluation of the Proposed Change

3.0 BACKGROUND

The Unit 2 drywell cooling system consists of eight unit coolers, each of which contains two redundant cooling coils and fans. Each fan is rated to deliver 7,000 cfm of conditioned air at approximately 78°F to selected locations within the drywell. During normal operation one fan in each unit cooler is in service and the second fan is in standby. On a loss of the operating fan, the standby fan will automatically start to assure continuous cooling capability.

According to TS Bases 3.6.1.7, the TS limit for drywell average air temperature ensures that the containment peak air temperature does not exceed the drywell design temperature of 340°F during postulated accident conditions.

A review of prior operating history for both the Unit 1 and Unit 2 drywell unit coolers has shown that both fans on a single unit cooler have not been out of service concurrently during normal plant operation. There have been several occasions when a single fan has been out of service.

On those occasions, the redundant 100% capacity fan successfully operated and maintained the drywell average air temperature at normal operating conditions until the out-of-service fan was repaired and returned to service.

On October 24, 2005, one of the 2D drywell unit cooler fans (2D1V212) failed and was removed from service. The redundant 100% capacity fan was placed in service and the drywell average air temperature was maintained at approximately 129°F. Based on investigation of the fan failure, it was determined that maintenance on the failed drywell unit cooler fan would require drywell entry during a unit shutdown. The drywell unit coolers that are included in the LGS TS are the A, B, G and H unit coolers. A failure of both fans concurrently on either of the TS drywell unit coolers would place the unit in a 30-day shutdown LCO. However, since the 2D drywell unit cooler is not in TS, a failure of the other fan (2D2V212) on the 2D drywell unit cooler in addition to the failed 2D1 fan would not place the unit in a 30-day shutdown LCO. Also, it was not recognized at the time of the 2D1 drywell unit cooler fan failure that if the 2D2 drywell unit cooler fan also failed, it would significantly affect drywell average air temperature. As indicated previously, there have been several drywell unit cooler fan failures, but no history where a pair of fans failed at the same time. As a result, the 2D1 drywell unit cooler fan was coded for repair during the next scheduled refueling outage (2R09) through the work management process.

Subsequently, on February 22, 2006, LGS Unit 2 was shut down for a planned maintenance outage which involved a drywell entry to replace leaking safety relief valves (SRVs). A scope control meeting was held for this maintenance outage prior to the shutdown. Items coded for forced outage, main control room distractions, potential Limiting Condition for Operation (PLCO) logs, load drop and emergent issues were considered for scope as part of the forced outage process. As discussed above, the failed 2D1 drywell unit cooler fan was coded for repair during the next scheduled refueling outage, there was no PLCO condition associated with the failed 2D1 fan, and the redundant 2D2 fan was successfully maintaining the drywell average air temperature at normal operating conditions. Therefore, repair of the failed 2D1 fan was not considered for the SRV maintenance outage. As a result, the 2D1 drywell unit cooler fan was not repaired at that time.

On April 2, 2006, the second fan (2D2V212) for the 2D drywell unit cooler also failed and was removed from service. As a result, the drywell average air temperature rose from approximately

Exigent License Amendment Request Attachment 1 Docket No. 50-353 Page 3 of 8 Evaluation of the Proposed Change 129°F to approximately 142°F. Plant action, to lower the chilled water supply temperature to the lower operating band, has resulted in lowering the drywell average air temperature to approximately 140.5°F based on comparable environmental conditions. In addition, drywell average air temperature is determined once per shift.

Historically, LGS has experienced an increase in the drywell average air temperature of 2 - 4°F during the summer months with normal drywell air cooling system operation. Under the current plant condition, this could result in the potential to exceed the TS limit of 145°F. If the drywell average air temperature exceeds the limit of 145°F, TS 3.6.1.7 requires that the average air temperature be reduced to within the limit within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, or be in Hot Shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in Cold Shutdown within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Adding a footnote to the TS limit of 145°F would allow continued operation of LGS, Unit 2, with drywell average air temperature no greater than 148°F for no longer than the remainder of the current operating cycle (Cycle 9),

which would prevent a TS-required shutdown due to the degraded condition of the nonsafety-related drywell air cooling system.

Noticing this license amendment request in the Biweekly Federal Register Notice for the standard 30-day public comment period would not expire until July 2006. Therefore, the combination of the increase in the drywell average air temperature during the summer months and the standard regulatory process for noticing license amendment requests could result in an unwarranted plant shutdown. As a result, Exelon requests approval of the requested license amendment on an exigent basis in accordance with the requirements of 10 CFR 50.91(a)(6).

At this time, Exelon is not requesting to increase the TS limit for the drywell average air temperature on a permanent basis. As discussed previously, both fans being out of service at the same time during normal plant operation is considered to be an infrequent occurrence. In addition, there is insufficient time to completely re-evaluate the environmental qualification of SSCs in the drywell for operating at the higher average air temperature on a permanent basis prior to reaching the summer months.

4.0 TECHNICAL ANALYSIS

The principal safety concerns related to increasing the TS limit for drywell average air temperature for the remainder of the current operating cycle are as follows: (1) the impact on peak containment analysis parameters (e.g., temperature and pressure) during a design basis accident (DBA), (2) the impact on the design basis of mechanical and structural SSCs in the drywell, and (3) the effect on the qualified life of safety-related components in the drywell.

4.1 Analysis of Peak Containment Parameters The TS limit for drywell average air temperature ensures that the drywell design temperature would not be exceeded by the peak drywell temperature during a postulated DBA. The drywell design temperature of 340°F was selected to ensure containment integrity and to ensure that SSCs required to mitigate the consequences of a DBA would be capable of performing their design functions under postulated drywell temperature conditions. Generally, peak values for containment analysis parameters (e.g., temperature and pressure) have a strong dependence upon the initial conditions of the primary system (e.g., enthalpy) and the size of the breach in the primary system pressure boundary. In contrast, a relatively small change in the initial drywell average air temperature would be expected to have a minor effect on the peak containment analysis parameters. Nevertheless, the TS limit for drywell average air temperature is important

Exigent License Amendment Request Attachment 1 Docket No. 50-353 Page 4 of 8 Evaluation of the Proposed Change in that it establishes the initial drywell air temperature condition which provides assurance that the peak containment analysis parameters will not be exceeded.

As indicated in Section 6.2.1.8 of the LGS Updated Final Safety Analysis Report (UFSAR), the current LGS containment design was evaluated during Power Rerate for the DBA Loss-of-Coolant Accident (LOCA). The containment analyses were performed in accordance with Regulatory Guide 1.49, entitled "Power Levels of Nuclear Power Plants," using General Electric (GE) codes and models that have been approved by the NRC for plant-specific licensing applications. The M3CPT code was used to determine the short-term containment response, and the SHEX code was used to determine the long-term containment response.

Table 6.2-4A of the LGS UFSAR identifies the significant input parameters and initial conditions for the Power Rerate containment analyses. This table indicates that the current short and long-term containment analyses for LGS are based upon an initial drywell average air temperature of 150°F. These containment analyses demonstrate that, given an initial drywell average air temperature of 150°F, neither the drywell design temperature of 340°F nor the drywell design pressure of 55 psig would be exceeded during a DBA. In addition, as indicated in LGS UFSAR Table 6.2-5A, these containment analyses demonstrate that the peak suppression pool temperature is within the suppression pool structural design value of 220°F, and does not exceed the low pressure Emergency Core Cooling System (ECCS) pump net positive suction head (NPSH) limit of 212°F. The proposed change is also bounded by the current small line break analysis.

Based upon the foregoing evaluation, it is concluded that the proposed one-time TS limit of 148°F for drywell average air temperature for no longer than the remainder of the current operating cycle would not result in peak containment parameters exceeding their design values during a design basis accident.

4.2 Mechanical and Structural Drywell SSC Design Basis The TS limit for drywell average air temperature also ensures that the design basis for safety-related mechanical and structural SSCs in the drywell is not exceeded. The mechanical and structural SSCs in the drywell were previously evaluated up to a drywell average air temperature of 150°F. Therefore, a drywell average air temperature of 148°F for no longer than the remainder of the current operating cycle would not adversely affect their capabilities to function as designed.

The one-time increase to the TS limit for drywell average air temperature does not change the existing methodology for determining drywell average air temperature. In addition, the instrument uncertainty associated with developing the drywell average air temperature is not changing. Based on the number of instrument data points measured, and the method of averaging the data, these uncertainties have minimal impact on the drywell average air temperature calculations. Also, the proposed change does not adversely effect calibration of reactor instrumentation contained in the drywell.

Table 3.8-3 of the LGS UFSAR specifies that the design temperature for Seismic Category I structures has been evaluated and determined that increasing the initial drywell average air temperature to 150°F would not adversely affect the ability of any Seismic Category I structure from performing its design function. Therefore, the effect of the potential temperature increase upon Seismic Category I structures is negligible and acceptable.

Exigent License Amendment Request Attachment 1 Docket No. 50-353 Page 5 of 8 Evaluation of the Proposed Change Based upon the foregoing evaluation, it is concluded that the proposed one-time TS limit of 148°F for drywell average air temperature for no longer than the remainder of the current operating cycle would be consistent with the design basis of structures and mechanical systems and components in the drywell.

4.3 Environmental Qualification of Safety-Related Components in the Drywell The environmental qualification of components installed at LGS, Unit 2, is discussed in UFSAR Section 3.11. Under conditions postulated to occur during its installed life, safety-related components must be capable of performing their safety function. For components in the drywell, the qualified life was based on operation at a minimum drywell average air temperature of 145°F. An evaluation of the qualified life of components in the drywell has been performed and has determined that current qualification will not be adversely impacted even if the components are exposed to a temperature of 150°F for the remainder of the current operating cycle. This conclusion is based on the fact that, for the first half of the current operating cycle, drywell average air temperature has been maintained below 132°F (13°F below which the current qualified life is based). The resultant increase in qualified life, from operating below the temperature at which current qualified life of drywell components is based on, is greater than the decrease in qualified life for the potential operation at 148°F drywell average air temperature (3°F above which the current qualified life is based) for the remainder of the current operating cycle. Therefore, limiting drywell average air temperature to no greater than 148°F for no longer than the remainder of the operating cycle will maintain environmental qualification of the components in the drywell. The impact of localized drywell temperatures exceeding 150°F, as identified through the normal drywell average air temperature monitoring performed in accordance with TS Surveillance Requirement 4.6.1.7, has been evaluated.

Based on the discussion above, it is concluded that the proposed one-time TS limit of 148°F for drywell average air temperature for no longer than the remainder of the current operating cycle will not have an adverse effect on the qualified life of drywell components.

5.0 REGULATORY ANALYSIS

5.1 No Significant Hazards Consideration Exelon has evaluated whether or not a significant hazards consideration is involved with the proposed amendments by focusing on the three standards set forth in 10 CFR 50.92, Issuance of amendment, as discussed below:

1. Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No. The increase in the allowable drywell average air temperature during normal plant operation does not make any physical changes to the plant. It only permits the plant to operate at a higher drywell average air temperature for a limited period of time, and therefore, does not increase the probability of an accident previously evaluated. This increase in the drywell average air temperature has been evaluated to ensure that the change does not adversely affect the ability of the primary containment to perform its safety related function during accident conditions.

Exigent License Amendment Request Attachment 1 Docket No. 50-353 Page 6 of 8 Evaluation of the Proposed Change The LGS containment design was previously evaluated using an initial average air temperature of 150°F for the design basis Loss-of-Coolant Accident (LOCA). The results of this evaluation showed that the peak drywell air temperature does not exceed the limit of 340°F post-accident and that the peak drywell pressure does not exceed the design limit of 55 psig. In addition, the results of this evaluation showed that the peak suppression pool temperature does not exceed the suppression pool structural design limit of 220°F, and does not exceed the low pressure Emergency Core Cooling System (ECCS) pump net positive suction head (NPSH) limit of 212°F. The proposed change is also bounded by the current small line break analysis.

Evaluation of components in the drywell has determined that the proposed one-time increase in the drywell average air temperature does not adversely affect the capability to perform their safety function. For components in the drywell, the qualified life was based on operation at a minimum drywell average air temperature of 145°F. An evaluation of the qualified life of components in the drywell has been performed and has determined that current qualification will not be adversely impacted even if the components are exposed to a temperature of 150°F for the remainder of the current operating cycle. The increased average air temperature of the drywell atmosphere does not degrade or compromise any coolant boundaries nor does it degrade or compromise any primary containment boundaries from performing their design functions during or following an accident condition. This proposed change does not result in or require any systems or components to be operated outside of their design limits.

This proposed change does not adversely affect mitigating systems, structures or components, and does not adversely affect the initial conditions of any accidents.

Redundancy and diversity of mitigating systems are unchanged as a result of this proposed change. This proposed change does not affect onsite or offsite radiological consequences of any accident previously evaluated in the Safety Analysis Report (SAR).

Therefore, this proposed TS change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

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

Response: No. The one-time increase in the drywell average air temperature proposed by this TS change does not change any SSC of the plant. This TS change does not create new operating or failure modes. The normal operating drywell average air temperature is maintained to prevent the peak temperature/pressure of the primary containment from exceeding the design limit, and to ensure that SSCs perform their safety functions before, during and after accident conditions. A previous evaluation has shown that the limits for the drywell and suppression pool design temperatures and pressures are not exceeded by the proposed change.

Therefore, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.

Exigent License Amendment Request Attachment 1 Docket No. 50-353 Page 7 of 8 Evaluation of the Proposed Change

3. Does the proposed change involve a significant reduction in a margin of safety?

Response: No. This proposed change will allow the plant to operate at a higher drywell average air temperature during normal operation for the remainder of the current operating cycle. This higher drywell average air temperature (148°F) is still below the initial conditions (150°F) specified in the current short and long-term containment analyses. This change does not create additional heat loads or change the way any of the equipment is operated. A previous evaluation has demonstrated that the drywell and suppression pool design pressures and design temperatures and code requirements are maintained. Therefore, this one-time change to the TS drywell average air temperature limit, to allow the plant to operate no greater than 148°F for no longer than the remainder of the current operating cycle, does not have any adverse effect on the ability of safety-related SSCs to perform their design functions. The SSCs are designed to function following a LOCA where drywell temperature can peak at 340°F. For components in the drywell, the qualified life was based on operation at a minimum drywell average air temperature of 145°F. An evaluation of the qualified life of components in the drywell has been performed and has determined that current qualification will not be adversely impacted even if the components are exposed to a temperature of 150°F for the remainder of the current operating cycle.

Therefore, this proposed change does not involve a significant reduction in a margin of safety.

Based on the above, Exelon concludes that the proposed change presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and accordingly, a finding of no significant hazards consideration is justified.

5.2 Applicable Regulatory Requirements/Criteria 10 CFR 50, Appendix A, General Design Criterion (GDC) 16, "Containment design,"

requires that the reactor containment and associated systems be provided to assure that the containment design conditions important to safety are not exceeded for as long as postulated accident conditions require. Additionally, 10 CFR 50, Appendix A, GDC 50, "Containment design basis," requires that the reactor containment structure be designed so that the containment structure and its internal compartments can accommodate the calculated pressure and temperature conditions resulting from any loss-of-coolant accident.

The current containment analysis for LGS, Unit 2, is based upon an initial drywell average air temperature of 150°F, and demonstrates that neither the drywell design temperature of 340°F nor the drywell design pressure of 55 psig would be exceeded during a DBA. Thus, the proposed one-time TS limit of 148°F for drywell average air temperature for no longer than the remainder of the current operating cycle would not require a change to the current containment analysis, and therefore, would not result in peak containment parameters exceeding their design values during a DBA. Based on this evaluation, the requirements of GDC 16 and GDC 50 would continue to be satisfied as a result of the proposed change.

10 CFR 50, Appendix A, GDC 4, "Environmental and dynamic effects design bases,"

requires that SSCs important to safety be designed to accommodate the effects of and to be compatible with the environmental conditions associated with normal operation, maintenance, testing, and postulated accidents, including loss-of-coolant accidents. The design temperature for Seismic Category I structures has been evaluated and determined

Exigent License Amendment Request Attachment 1 Docket No. 50-353 Page 8 of 8 Evaluation of the Proposed Change that an initial drywell average air temperature of 150°F would not adversely affect the ability of any Seismic Category I structure to perform its design function. Therefore, the proposed change is consistent with the design basis of SSCs in the drywell, and the requirements of GDC 4 would continue to be satisfied as a result of the proposed change.

10 CFR 50.49, "Environmental qualification of electric equipment important to safety for nuclear power plants," requires that each holder of a license for a nuclear power plant establish a program for qualifying the electrical equipment defined in paragraph (b) of this regulation. Paragraph (e)(1) of 10 CFR 50.49 requires that the time-dependent temperature and pressure at the location of the electrical equipment important to safety must be established for the most severe design basis accident during or following which the equipment is required to remain functional. For components in the drywell, the qualified life was based on operation at a minimum drywell average air temperature of 145°F. An evaluation of the qualified life of components in the drywell has been performed and has determined that current qualification will not be adversely impacted even if the components are exposed to a temperature of 150°F for the remainder of the current operating cycle. The impact of localized drywell temperatures exceeding 150°F, as identified through the normal drywell average air temperature monitoring performed in accordance with TS Surveillance Requirement 4.6.1.7, has been evaluated. Therefore, the components in the drywell will remain within the limitations of the Environmental Qualification program which will continue to ensure that the requirements of 10 CFR 50.49 are satisfied.

In conclusion, based on the considerations discussed above, (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 (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.

6.0 ENVIRONMENTAL CONSIDERATION

A review has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure.

Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement, or environmental assessment need be prepared in connection with the proposed amendment.

7.0 REFERENCES

None

ATTACHMENT 2 Exigent License Amendment Request Limerick Generating Station, Unit 2 Docket No. 50-353 Proposed One-Time Change to the Drywell Average Air Temperature Limit - Technical Specification 3.6.1.7 Marked-up Technical Specifications Page Unit 2 TS Page 3/4 6-10

CONTAINMENT SYSTEMS DRYWELL AVERAGE AIR TEMPERATURE LIMITING CONDITION FOR OPERATION 3.6.1.7 Drywell average air temperature shall not exceed 145°F **.

APPLICABILITY: OPERATIONAL CONDITIONS 1, 2, and 3.

ACTION:

With the drywell average air temperature greater than 145°F , reduce the average air temperature to within the limit within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> or be in at least HOT SHUTDOWN within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Revise per this License Amendment Request SURVEILLANCE REQUIREMENTS 4.6.1.7 The drywell average air temperature shall be the volumetric average of the temperatures at the following locations and shall be determined to be within the limit at least once per 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />s:

Approximate Number of Elevation Installed Sensors *

a. 330' 3

b. 320' 3

c. 260' 3

d. 248' 6

• At least one reading from each elevation is required for a volumetric average calculation.

• • Operation may continue with drywell average air temperature no greater than 148°F for the remainder of the current operating cycle (Cycle 9) , or until the next shutdown of sufficient duration to allow for unit cooler fan repairs, whichever comes first.

LIMERICK - UNIT 2 3/4 6-10 Amendment No. 121