SVP-12-083, Extension of Provisional Variance (IEPA-12-19) from National Pollutant Discharge Elimination System (NPDES) Permit No. IL0005037

Extension of Provisional Variance (IEPA-12-19) from National Pollutant Discharge Elimination System (NPDES) Permit No. IL0005037

ML12226A402
Person / Time
Site:	Quad Cities
Issue date:	08/08/2012
From:	Hanley T Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
IEPA-12-19, SVP-12-083, IL0005037
Download: ML12226A402 (42)

Text

Exelkn.

Exelon Generation Company, LLC Ouad Cities Nuclear Power Station 22710 2o6th Avenue North Cordova, I L 61242-9740 www.exeloncorp.com Nuclear SVP-12-083 August 8, 2012 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Quad Cities Nuclear Power Station, Units 1 and 2 Renewed Facility Operating License Nos. DPR-29 and DPR-30 NRC Docket Nos. 50-254 and 50-265

Reference:

Extension of Provisional Variance (IEPA-12-19) from National Pollutant Discharge Elimination System (NPDES) Permit No. IL0005037 Letter from Tim Hanley (Exelon Generation Company, LLC) to U. S. NRC, "Provisional Variance (IEPA-12-19) from National Pollutant Discharge Elimination System (NPDES) Permit No. IL0005037," dated July 27, 2012 The referenced letter submitted a copy of provisional variance IEPA-12-19 that was granted from NPDES Permit 1L0005037. Quad Cities Nuclear Power Station (QCNPS) requested extensions to that provisional variance on July 12, 2012 and July 19, 2012.

Pursuant to Appendix B (Section 2.2) of the Renewed Facility Operating Licenses for QCNPS, enclosed are those provisional variance (IEPA-12-19) extension requests and the associated Illinois Environmental Protection Agency approvals.

Should you have any questions concerning this letter, please contact Mr. Wally J. Beck at (309) 227-2800.

Respectfully, Site Vice President Quad Cities Nuclear Power Station

Enclosures:

A - Provisional Variance Extension Request (July 12, 2012) and Approval B - Provisional Variance Extension Request (July 19, 2012) and Approval cc:

Regional Administrator - NRC Region III NRC Senior Resident Inspector - Quad Cities Nuclear Power Station (jVD\\

Enclosure A Provisional Variance Extension Request (July 12, 2012) and Approval

Exelkn.

Exelon Generation Company, LLC www.exeloncorp.comN Quad Cities Nuclear Power Station Nuclear 22710 206th Avenue North Cordova, IL 61242-9740 SVP-12-072 July 12, 2012 Mr. Roger Callaway (CAS-t9)

Wastewater Compliance Unit Manager Illinois Environmental Protection Agency Bureau of Water Compliance Assurance Section #19 1021 North Grand Avenue East P.O. Box 19276 Springfield, Illinois 62794-9274

Subject:

Quad Cities Nuclear Power Station NPDES Permit No. IL0005037 Provisional Variance 12-19 Extension Request - Emergency Application

Dear Mr. Callaway:

Exelon Generation Company, L.L.C. ("Exelon") hereby requests that the Illinois Environmental Protection Agency ("IEPA" or "Agency") grant an extension to provisional variance IEPA-12-19 issued on July 2, 2012 for Quad Cities Nuclear Power Station

("Quad Cities", "Station", or "Facility"), pursuant to Section 35(b) of the Environmental Protection Act ("Act") 415 ILCS 5/35. Exelon submits this Application for a provisional variance extension consistent with IEPA procedures at 35 Illinois Administrate Code 104.300. The Station discharges wastewater pursuant to NPDES Permit No.

IL0005037, which IEPA issued on August 26, 2010 with expiration date of August 31, 2015. Exelon requests the provisional variance be extended 10 days for Quad Cities Station allowing the station to exceed the non-excursion hour temperature limit for July of 860F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of July 16, 2012 through July 25, 2012 by no more than 50F (91 OF for July) or 20F above ambient river temperature, whichever is greater. There has been no biological harm to the environment as a result of provisional variance IEPA-12-19 issued to Quad Cities Station on July 3, 2012 and effective July 7, 2012 through July 15, 2012.

=

Background===

Quad Cities Station is a base load nuclear-fueled steam electric generating facility located near Cordova, Illinois, on the Mississippi River at River Mile 506.8. The station operates two boiling water reactors which have a combined maximum generating capacity of 5,914 megawatts thermal. The station is currently operating at 100%

capacity. The station's capacity factor January 1, 2012 through May 31, 2012 was 89%.

Quad Cities Station generation output is transmitted to the PJM Interconnection Grid.

PJM Interconnection is a regional transmission organization (RTO) that coordinates the movement of wholesale electricity in all or parts of Delaware, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and the District of Columbia.

Circulating water used to cool and condense the steam from the generating process is withdrawn from, and discharged to, the Mississippi River (Receiving Stream Water ID-IL_M-02). The current Mississippi River flow is 93,000 cfs and the 7Q10 is 13,700 cfs.

The incoming water is currently listed as impaired (2012 listing) due to Mercury, Polychlorinated biphenyls, and Manganese. These impaired waters have a designated use of public and food processing water as well as fish consumptions.

Quad Cities operates a condenser cooling water system in open cycle mode. In this mode, cooling water is drawn from the Mississippi River into an intake canal, passes through the plant systems, and is discharged through diffusers into the Mississippi River. The maximum design flow is 2,253 cfs or 1,011,000 gpm. The maximum temperature rise of the station from intake to effluent is 280F at design flow of 2,253 cfs.

Open cycle operation with the diffusers was initially permitted by the IEPA on December 22, 1983. Quad Cities Station effluent temperature rise downstream of the diffusers at the edge of the mixing zone is limited to 50F per Special Condition 7(a) of NPDES Permit No. IL0005037.

Temperature monitoring data shows that the Mississippi River water temperature at the station's intake exceeded the non-excursion hour July temperature standard of 86 0F on July 5, 2012 and remained above 860F through July 10, 2012. The available temperature data shows that the Mississippi River water temperature at the station's intake is approaching and may again exceed the non-excursion hour July temperature standard of 86 0F based on latest weather forecasts. The upstream Mississippi River temperature was measured at 84 0F on July 11, 2012, as a result of these conditions, Quad Cities Station expects to exceed the non-excursion hour temperature limit for July of 86 0F on July 13, 2012. Based on current weather forecast of daily maximum air temperatures in the 90's°F starting July 13 for seven days, ambient Mississippi River water temperature may reach 860F. Mississippi River flow is currently 68,000 cfs and forecast to decrease to 50,000 cfs by July 17, 2012. The maximum Mississippi River ambient temperature the station will be able to comply with during the provisional variance period without the use of excursion hours is 85°F.

As a consequence of the unusually warm weather, high ambient river temperatures, and the absence of cooling during the evening hours, the capacity of the Mississippi River to dissipate heat has been reduced beyond its normal capabilities. Even at current flow rates of 68,000 cfs, the river is not cooling off during the evening hours as is typical this time of year. Without nighttime cooling, the river retains the heat introduced to it during the daytime hours, both upstream and downstream of the station.

At no time has the difference between ambient river temperature and the temperature at the edge of the mixing zone exceeded 5 degree F. In fact, based on modeling, the difference between ambient river temperature and the temperature at the edge of the mixing zone has not exceeded 1 degrees F.

Relief Requested A provisional variance extension is being requested from the restriction in Special Condition 7B of the NPDES Permit that limits the number of excursion hours to 1 %

(87.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />) of the hours in a 12-month period ending with any month. Specifically, Special Condition 7B provides that the Station shall not cause water temperatures in the Mississippi River (beyond the mixing zone) to exceed by more than 30F the non-excursion hour temperature limit for July of 86 0F.

Exelon requests an extension to provisional variance IEPA-12-19 be issued to Quad Cities Station allowing the station to exceed the non-excursion hour temperature limit for July of 86 0F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of July 16, 2012 through July 25, 2012 by no more than 5°F (91 OF for July) or 20F above ambient river temperature, whichever is greater.

Necessity for Request When the ambient river temperatures approach or exceed the non-excursion hour limits, the Station has no option other than to use excursion hours, and once its allotment of excursion hours is depleted, the Station must cease operating altogether to maintain compliance with the NPDES Permit. Partial deratings or adding cooling facilities (such as cooling towers) will not allow the Station to achieve compliance with a limit that already is exceeded even before any heat is added as a result of Station operations.

Special Condition 7B of NPDES Permit limits the temperature at the edge of the mixing zone to 86°F in July, except when the Station is using excursion hours, during which time the temperatures at the edge of the mixing zone may be 30F warmer than these limits. As a rule, Quad Cities has been able to operate well within its permitted thermal limits due to the fact that the ambient temperatures of the River (measured upstream of the discharge) generally remain below the non-excursion hour limit. It is only during periods when the ambient river temperatures are very close to or exceed the non-

excursion hour limits or during periods of extreme low flows that the Station is forced to use a significant number of its excursion hour allowance.

In 2012 Quad Cities Station first began using excursion hours on Sunday, March 1 8 th when upstream Mississippi River temperature matched the station's effluent limitation of 57 0F. The permitted excursion hours were subsequently exhausted in March as a result of continued record breaking warm weather recorded throughout the mid-western states. Quad Cities Station submitted a request to IEPA on March 20, 2012 for relief from Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of March 21, 2012 to April 1, 2012. IEPA subsequently issued Provisional Variance IEPA 12-11 to Quad Cities Station on March 21, 2012 allowing the station to exceed the non-excursion hour temperature limit for March of 570F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of March 21, 2012 to April 1, 2012 by no more than 50F (620F for March) or 20F above ambient river temperature, whichever is greater. A total of 223.5 excursion hours were accumulated by Quad Cities Station during March of 2012.

Quad Cities Station submitted a 2 nd request to IEPA on May 24, 2012 for relief from Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of May 26, 2012 thru May 29, 2012. IEPA subsequently issued Provisional Variance IEPA 12-17 to Quad Cities Station on May 25, 2012 allowing the station to exceed the non-excursion hour temperature limit for May of 780F stated in Special Condition 7(b) of NPDES Permit No.

IL0005037 for the period of May 26, 2012 thru May 29, 2012 by no more than 50F (78 0F for May) or 20F above ambient river temperature, whichever is greater. During the May Provisional Variance period, the station did not exceed the station's effluent limitation of 780F.

As you are aware, Illinois and the Upper Mississippi River basin are experiencing a long stretch of hot weather which is resulting in high ambient river temperatures. On July 1, 2012, 33 excursion hours became available when the 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> accumulated during July 2011 rolled off the rolling 12 month calendar. Quad Cities Station submitted a 3rd provisional variance request to IEPA on July 3, 2012 for relief from Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of July 5, 2012 thru July 15, 2012.

IEPA subsequently issued Provisional Variance IEPA 12-19 to Quad Cities Station on July 3, 2012 allowing the station to exceed the non-excursion hour temperature limit for July of 86 0F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of July 5, 2012 thru July 15, 2012 by no more than 5°F (91°F for July) or 20F above ambient river temperature, whichever is greater. The PV went into effect when stations remaining 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> of the rolling 12 month calendar were exhausted. The stations downstream receiving stream exceeded the non-excursion hour temperature limit for July of 860F on July 5, 2012 @ 16:00 when upstream Mississippi River temperature reached 860F. PV IEPA-12-19 became effective July 7, 2012 @ 01:00 when the remaining 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> of the rolling 12 month calendar were exhausted. The stations downstream receiving stream remained above 86 0F until 00:00 on July 11, 2012 when the upstream Mississippi River temperature dropped back down to 85 0F. A total of 128 excursion hours have been accumulated by Quad Cities Station since IEPA-

12-19 was issued. During the period of July 5, 2012 thru July 12, 2012, the maximum upstream Mississippi River temperature measured was 88 0F. The maximum downstream receiving stream temperature measured was 890F.

IEPA also issued Provisional Variances to Exelon's Braidwood Station (IEPA-12-12),

Dresden Station (IEPA-12-14), and LaSalle Station (IEPA-1 2-15) for thermal effluent relief during the March 2012 heat wave. IEPA issued a Provisional Variance to Dresden Station on July 6, 2012 (IEPA-12-22).

With the current forecast, it is expected that Quad Cities Station will exceed the non-excursion hour temperature limit for July of 860F starting July 13, 2012 thru July 25, 2012 in order to continue to provide safe reliable power to the grid.

Based on current weather forecasts it is expected that the Mississippi River will approach or exceed Quad Cities Station's permitted effluent limitation. Therefore, unless relief is granted by way of this provisional variance extension request, it is likely that the Station will be forced to shut down for correspondingly significant durations.

Since derating the units will not ensure compliance with the effluent limitations shutting the units down may be the only alternative. Removing both units from operation will not only reduce the available power supply to the grid but will also result in the need for power from the grid to operate key nuclear safety systems. The time required to return nuclear generating units to full power can require 18-24 hours meaning the electricity generated from these systems will not be readily available in the event of an emergency. Furthermore, under normal conditions only one of the two reactors would be removed from service at any given time allowing the operating unit to be the primary backup power source for the non-operating unit. Removing both units from service will also eliminate this redundancy and will increase the stations' reliance on off-site power to support safety related systems. With both unit's offline, and unable to immediately return to service, the power that Quad Cities Station could generate as a result of the requested provisional variance would not be available to support the voltage requirements that could occur under changing grid conditions. As of July 11, 2012, PJM grid status does not currently have or project any alerts, warnings, or actions. PJM predicts an anticipated Peak Load >146, 000 MW on Tuesday 7/17/2012.

In cooperation with IEPA's request that Exelon explore long-term thermal relief options for Quad Cities, Exelon commissioned extensive studies of the Station's thermal output and impacts. Exelon has shared those studies and its draft long-term regulatory relief proposal with both Federal and State regulators. Additionally, Quad Cities Station submitted a draft of its 316(a) thermal report which demonstrates no harm to indigenous aquatic populations to the IEPA, obtained comments, revised the report and then resubmitted the document for the Agency's final review and comment. At this time, the Agency's technical review of the Draft 316 (a) Report is nearing completion. The Agency will be presenting its technical comments on the Draft 316 (a) Report to Exelon and the Director of the Agency. Exelon is working on finalizing the Draft Adjusted Thermal Standard (ATS) petition to the Illinois Pollution Control Board (IPCB) which was

be submitted to the Agency for their internal review on July 5, 2012. Based on guidance received from the Agency's Legal Counsel, our next follow-up call with the Agency is going to be Monday, July 1 6 th when we expect to receive Agency feedback on the Draft 316 (a) Report as well as the Draft ATS petition to the Illinois Pollution Control Board.

Assessment of Environmental Impacts The biological structure and condition of the receiving water has been well documented due to the ongoing Quad Cities Station Long-term Monitoring Program which began in 1971. This data is annually presented to ILEPA as well as other stakeholders throughout the state. No adverse effects to the local fish or mussel populations have been observed from similar requests in the past. Therefore, no adverse effects are anticipated with this thermal discharge provisional variance. The station recently completed a draft 316(a) demonstration that the agency has in its possession.

Because Quad Cities Station is not proposing to increase cooling water flows or increase the temperature of cooling water discharges, there will be no increase in impingement or entrainment as a result of the issuance of the requested Provisional Variance. Additionally, because the ambient river temperature increase has been gradual, resident fish species have either acclimated to the higher temperature or have found thermal refuge. In addition, the current flows afford a delta T of approximate 1 OF between the upstream and downstream temperatures. Therefore, resident fish species will not be subject to any heat shock as a result of increasing the allotment of excursion hours for Quad Cities Station.

The biological studies undertaken as part of Exelon's above-mentioned investigation of long-term, permanent relief options considered the effects on species of fish and shellfish that could result from increasing the number of excursion hours available to the plant. These studies support the conclusion that granting the requested Provisional Variance will not cause significant or unacceptable adverse effects to these species.

Species of fish that are likely to suffer from being exposed to temperatures in the excursion zone (i.e. up to 50F above the monthly standard) will already have taken refuge from the higher than normal ambient river temperatures. In 2006, a species specific die-off occurred in the incoming and receiving water during an elevated water temperature period. That specific incident continued to be captured in the QC Station dataset for several weeks after the first record. The die-off was the result of temperatures increasing at a rate in excess of the mooneyes adaption capabilities. No fish kills have occurred as a result of the station discharge. Therefore, no fish mortality should result from operations authorized by the Provisional Variance. Due to the high current flows, this situation is not anticipated.

This provisional variance request is due to the elevated temperature of the incoming water, not temperature differential; therefore, avoidance behavior outside the mixing zone is not anticipated because adequate flows are occurring for a minimal temperature differential.

Shellfish do not have similar thermal avoidance capabilities. However, the recently conducted biological studies show that the mussel (unionid) species in beds that are closest to the plant's discharge are generally more temperature tolerant, and are capable of surviving relatively short-term elevated thermal exposures. Species thought to be less thermally-tolerant inhabit beds located further downstream, in the Cordova Bed, located about 1 mile downstream from the plant. However, because the considerable distance between the plant to the Cordova and the flow characteristics of the River (that cause much of the plant's thermal discharge to avoid the Cordova Bed) the Provisional Variance should not cause any appreciable harm to mussel species downstream of the plant.

If the variance is granted, the station will monitor the waters upstream, near the intake, and downstream for detrimental effects to the fishery as noted in previous provisional variances. Visual inspections will take place 3 times during the day and if necessary, a complete visual and water quality assessment will take place in the late afternoon of each day at prescribed areas up and downstream of the plant. This will only take place if any evidence of fish mortality is currently occurring or has occurred. The station fishery biologist will be responsible for this assessment with consultation with the local governing agencies, if necessary. Late afternoon is when the potential effects would be most noticeable, but assessments will occur at the first sign of an issue. Our current biological program will capture and short-term and long-term effects of a provisional variance.

Alternatives to Requested Relief Historically, Quad Cities Station has used excursion hours during periods of extreme heat and low-river flows. Due in part to the mixing capacity provided by the Mississippi River, and the fact that ambient river temperatures rarely exceed the non-excursion hour NPDES Permit limits, only a relatively small percentage of the permitted excursion hours typically are used to cover any one of these periods. Unless a provisional variance is issued, when the Station runs out of hours, it will have to shut down during all times that the ambient river temperatures are at or above the non-excursion hour limit. Based on river temperatures recorded so far this summer and long range weather projections for the balance of the season, it is likely that there will be a number of extended periods during which ambient river temperatures will be at or above these limits. As previously explained, neither the option of derating the units nor of obtaining additional temporary cooling capacity will allow the Station to maintain compliance if the ambient river temperatures exceed the applicable temperature limits. The only option is for the Station to shut down once the ambient River temperatures are at or exceed the NPDES permit monthly limit.

In 2006, the station investigated the feasibility of installing cooling towers. Based on analytical evaluation of historical plant, river, and meteorological data, the proposed towers performance and the resulting reduction in downstream river temperature could be quantified. When the actual days when excursion hours occurred in the last six year period (2000-2005) were evaluated, there was no appreciable reduction in the number

of days when excursion hours would have occurred with the cooling towers in operation.

The reason for this is the high upstream river temperatures experienced on most of the days when actual excursion hours were recorded. For -80% of the days when excursion hours were recorded, the plant intake temperature was at the permit limited temperature or above (>86°F), and for the remaining 20% of the days, the intake temperature was within half a degree of the permit limits. For most of these occurrences, even if adequate cooling tower capacity was in operation to achieve a zero thermal impact on the river (i.e., the plant discharge temperature equaled the intake temperature), excursion hours nonetheless would have been recorded. Estimated cost in 2006 for installation of cooling towers ranged from $48 to $61 million.

Mitigative Actions to be Taken During the Variance Period During the period when the Station uses any additional excursion hours authorized by the requested provisional variance, Quad Cities Station will do the following: (1) continuously monitor the intake and discharge temperatures and assess water temperatures at the edge of the mixing zone using the NPDES Permit temperature monitoring curve or field measurements; (2) on a daily basis, inspect the intake and discharge areas to assess any mortalities to aquatic life, and report the results of these monitoring activities to the Agency within 30 days of the expiration of the provisional variance (or such other time as agreed upon by the Agency); and (3) notify the Agency of any significant adverse environmental conditions observed that might be caused by operations authorized by the provisional variance, including mortalities to fish or other aquatic life, investigate the cause of such conditions, provide the Agency updates regarding the situation, including when normal conditions return, and submit a report to the Agency regarding these matters within 30 days of the expiration of the provisional variance period (or such other time as agreed upon by the Agency).

Summary Exelon requests that an extension to provisional variance IEPA-1 2-19 be issued to Quad Cities Station allowing the station to exceed the non-excursion hour temperature limit for July of 86 0F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of July 16, 2012 through July 25, 2012 by no more than 50F (91 OF for July) or 20F above ambient river temperature, whichever is greater.

If you should have any questions regarding these matters, please feel free to contact Vicki Neels at (309) 227-3200 or Mark Stuhlman at (309) 227-2765 from Quad Cities or John Petro, Principal Environmental Analyst, Exelon Generation at (630) 657-3209.

Very Truly Yours, : 7 Tim Hanley Site Vice President Quad Cities Station TH/MS/sjo CC: Mark Stuhlman John Petro Letterbook

ILLINOIS ENVIRONMENTAL PROTECTION AGENCY July 12, 2012 Exelon Generation Company, L.L.C.

)

Quad Cities Nuclear Power Station

))

Petitioner,

))

v.

)

IEPA-12-19

)

(Provisional Variance Extension-Water)

ILLINOIS ENVIRONMENTAL

)

PROTECTION AGENCY,

))

Respondent.

)

Re:

Provisional Variance Extension From Discharge Limits Contained in NPDES Permit IL0005037

Dear Mr. Hanley:

On July 3, 2012, the Illinois Environmental Protection Agency (Agency) granted a request from Exelon Generation Company, L.L.C.'s Quad Cities Nuclear Power Station (Quad Cities) for a provisional variance (IEPA-12-19, Attachment A). This provisional variance is to end no later than July 15, 2012. On July 12, 2012, Quad Cities submitted a request for an extension to its provisional variance (Attachment B).

Quad Cities requests that the terms and conditions of this provisional variance from thermal limits in NPDES Permit IL0005037 (Attachment C) be extended, so that Quad Cities can continue operating through this unusually hot and dry period of weather and resulting high river temperatures.

The Agency has completed its technical review of the attached July 12, 2012 request for an extension of this provisional variance (Attachment B). Quad Cities is seeking a provisional variance extension from July 15, 2012 through July 25, 2012, that would allow it to exceed the maximum temperature limit in Special Condition 7B of NPDES Permit IL0005037 by no more than 50 (91 0 for July), or 2' above ambient river temperature, whichever is greater.

Based on its review, the Agency GRANTS Quad Cities a provisional variance extension subject to the specific conditions set forth below.

=

Background===

Quad Cities is a base load nuclear-fueled steam electric generating facility located near Cordova, Illinois, on the Mississippi River at River Mile 506.8. The station operates two boiling water reactors which have a combined maximum generating capacity of 5,914 megawatts thermal. The station is currently operating at 100% capacity. The station's capacity factor January 1, 2012 through May 31, 2012 was 89%., Quad Cities generation output is transmitted to the PJM Interconnection Grid. PJM Interconnection is a regional transmission organization (RTO) that coordinates the movement of wholesale electricity in all or parts of Delaware, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and the District of Columbia.

Circulating water used to cool and condense the steam from the generating process is withdrawn from, and discharged to, the Mississippi River (Receiving Stream Water ID-IL, M-02. The incoming water is currently listed as impaired (2012 listing) due to Mercury, Polychlorinated biphenyls, and Manganese. These impaired waters have a designated use of public and food processing water as well as fish consumptions.

Quad Cities operates a condenser cooling water system in open cycle mode. In this mode, cooling water is drawn from the Mississippi River into an intake canal, passes through the plant systems, and is discharged through diffusers into the Mississippi River. The maximum design flow is 2,253 cfs or 1,011,000 gpm. The maximum temperature rise of the station from intake to effluent is 287F at design flow of 2,253 cfs. Open cycle operation with the diffusers was initially permitted by the Agency on December 22, 1983.

Special Condition 7B of NPDES Permit IL00005037 (Attachment B) limits the temperature at the edge of the mixing zone to 86'F in July, except when Quad Cities is using excursion hours, during which time the temperatures at the edge of the mixing zone may be 3YF warmer than these limits.

Temperature monitoring data shows that the Mississippi River water temperature at Quad Cities' intake exceeded the non-excursion hour July temperature standard of 86'F on July 5, 2012, and remained above 86'F through July 10, 2012. The available temperature data shows that the Mississippi River water temperature at Quad Cities' intake is approaching and may again exceed the non-excursion hour July temperature standard of 86'F based on latest weather forecasts. The upstream Mississippi River temperature was measured at 84'F on July 11, 2012 and, as a result of these conditions, Quad Cities expects to exceed the non-excursion hour temperature limit for July of 86'F on July 13, 2012. Based on current weather forecast of daily maximum air temperatures in the 90's 0F starting July 13 for seven days, ambient Mississippi River water temperature may reach 86°F. Mississippi River flow is currently 68,000 cfs and forecast to decrease to 50,000 cfs by July 17, 2012. The maximum Mississippi River ambient temperature the station will be able to comply with during the provisional variance period without the use of excursion hours is 85°F.

As a consequence of the unusually warm weather, high ambient river temperatures, and the absence of cooling during the evening hours, the capacity of the Mississippi River to dissipate heat has been reduced beyond its normal capabilities. Even at current flow rates of 68,000 cfs, the river is not cooling off during the evening hours as is typical this time of year. Without nighttime cooling, the river retains the heat introduced to it during the daytime hours, both upstream and downstream of the station.

Quad Cities states that at no time has the difference between ambient river temperature and the temperature at the edge of the mixing zone exceeded 50 F. In fact, based on modeling, the difference between ambient river temperature and the temperature at the edge of the mixing zone has not exceeded 1 0 F.

In cooperation with the Agency's request that Exelon explore long-term thermal relief options for Quad Cities, Exelon commissioned extensive studies of the Station's thermal output and impacts. Exelon has shared those studies and its draft long-term regulatory relief proposal with both Federal and State regulators. Additionally, Quad Cities submitted a draft of its 316(a) thermal report which demonstrates no harm to indigenous aquatic populations to the Agency, obtained comments, revised the report and then resubmitted the document for the Agency's final review and comment. At this time, the Agency's technical review of the Draft 316 (a) Report is nearing completion. The Agency will be presenting its technical comments on the Draft 316 (a)

Report to Exelon and the Director of the Agency. Exelon is working on finalizing the Draft Adjusted Thermal Standard (ATS) petition to the Illinois Pollution Control Board (IPCB) which will be submitted to the Agency for their internal review before the end of the week.

Relief Requested Condition 7B of the NPDES Permit limits the number of excursion hours to 1% (87.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />) of the hours in a 12-month period ending with any month. Specifically, Special Condition 7B provides that the Station shall not cause water temperatures in the Mississippi River (beyond the mixing zone) to exceed by more than 3°F the non-excursion hour temperature limit for July of 860F.

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

F0 45 45 57 68 78 85 86 86 85 75 65 52 Quad Cities requests an extension to provisional variance IEPA-12-19 be issued to Quad Cities Station allowing the station to exceed the non-excursion hour temperature limit for July of 86°F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of July 16, 2012 through July 25, 2012 by no more than 5'F (91OF for July) or 2'F above ambient river temperature, whichever is greater.

Necessity for Request In its request, Exelon states that when the ambient river temperatures approach or exceed the non-excursion hour limits, Quad Cities has no option other than to use excursion hours, and once its allotment of excursion hours is depleted, Quad Cities must cease operating altogether to

maintain compliance with the NPDES Permit. According to Exelon, partial deratings or adding cooling facilities (such as cooling towers) will not allow Quad Cities to achieve compliance with a limit that already is exceeded even before any heat is added as a result of station operations.

Special Condition 7B of NPDES Permit limits the temperature at the edge of the mixing zone to 86°F in July, except when Quad Cities is using excursion hours, during which time the temperatures at the edge of the mixing zone may be 3YF warmer than these limits. As a rule, Quad Cities has been able to operate within its permitted thermal limits due to the fact that the ambient temperatures of the River (measured upstream of the discharge) generally remain below the non-excursion hour limit. It is only during periods when the ambient river temperatures are very close to or exceed the non-excursion hour limits or during periods of extreme low flows that Quad Cities uses its excursion hour allowance.

Illinois and the Upper Mississippi River basin are experiencing a long stretch of hot weather, which is resulting in high ambient river temperatures. In 2012 Quad Cities first began using excursion hours on Sunday, March 18th when upstream Mississippi River temperature matched the station's effluent limitation of 57'F. The permitted excursion hours were subsequently exhausted in March as a result of continued record breaking warm weather recorded throughout the mid-western states. Quad Cities submitted a request to the Agency on March 20, 2012, for relief from Special Condition 7(b) of NPDES Permit No. IL0005037, for the period of March 21, 2012, to April 1, 2012. The Agency subsequently issued Provisional Variance IEPA 12-11 to Quad Cities on March 21, 2012, allowing the station to exceed the non-excursion hour temperature limit for March of 57°F stated in Special Condition 7(b) of NPDES Permit No.

IL0005037 for the period of March 21, 2012 to April 1, 2012 by no more than 5'F (62'F for March) or 2°F above ambient river temperature, whichever is greater. During March of 2012, Quad Cities accumulated a total of 223.5 excursion hours.

Quad Cities submitted a second request to the Agency on May 24, 2012, for relief from Special Condition 7(b) of NPDES Permit No. IL0005037, from May 26, 2012, through May 29, 2012.

The Agency subsequently issued Provisional Variance IEPA 12-17 to Quad Cities on May 25, 2012, allowing the station to exceed the non-excursion hour temperature limit for May of 78'F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of May 26, 2012, through May 29, 2012, by no more than 5°F (78'F for May) or 2°F above ambient river temperature, whichever is greater. During the May Provisional Variance period, Quad Cities did not exceed its effluent limitation of 78°F. Quad Cities currently has 33 excursion hours that became available July 1, 2012, when the 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> accumulated during July 2011 rolled off the rolling 12-month calendar.

On July 1, 2012, 33 excursion hours became available when the 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> accumulated during July 2011 rolled off the rolling 12-month calendar. Quad Cities submitted a third provisional variance request to the Agency on July 3, 2012, seeking relief from Special Condition 7(b) of NPDES Permit No. IL0005037, from July 5, 2012, through July 15, 2012. The Agency issued Provisional Variance IEPA 12-19 to Quad Cities on July 3, 2012, allowing the station to exceed the non-excursion hour temperature limit for July of 86°F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of July 5, 2012, through July 15, 2012, by no more than 5°F (91°F for July) or 2'F above ambient river temperature, whichever is greater.

Provisional Variance IEPA-12-19 went into effect when Quad Cities' remaining 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> of the rolling 12-month calendar were exhausted. Quad Cities downstream receiving stream exceeded the non-excursion hour temperature limit for July of 86°F on July 5, 2012, at 4pm when upstream Mississippi River temperature reached 86°F. Provisional Variance IEPA-12-19 became effective July 7, 2012, at lam when the remaining 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> of the rolling 12-month calendar were exhausted. Quad Cities' downstream receiving stream remained above 86'F until 12am on July 11, 2012 when the upstream Mississippi River temperature dropped back down to 85°F.

Quad Cities has accumulated a total of 128 excursion hours since IEPA-12-19 was issued.

During the period of July 5, 2012, through July 12, 2012, the maximum upstream Mississippi River temperature measured was 88'F. The maximum downstream receiving stream temperature measured was 89'F.

The Agency also issued Provisional Variances to Exelon's Braidwood Station (IEPA-12-12),

Dresden Station (IEPA-12-14), and LaSalle Station (IEPA-12-15) for thermal effluent relief during the March 2012 heat wave. In addition, the Agency issued a Provisional Variance to Dresden Station on July 6, 2012 (IEPA-12-14).

With the current forecast, Quad Cities says it expects to exceed the non-excursion hour temperature limit for July of 86°F starting July 13, 2012, and going through July 25, 2012, if it is to be able to continue to provide safe reliable power to the grid.

Based on current weather forecasts it is expected that the Mississippi River will approach or exceed Quad Cities' permitted effluent limitation. Therefore, unless relief is granted by way of this provisional variance extension request, Quad Cities states that will be forced to shut down for correspondingly significant durations.

Because derating the units will not ensure compliance with the effluent limitations, Quad Cities says that shutting the units down may be the only alternative. Removing both units from operation will not only reduce the available power supply to the grid but will also result in the need for power from the grid to operate key nuclear safety systems. The time required to return nuclear generating units to full power can require 18-24 hours, meaning the electricity generated from these systems will not be readily available in the event of an emergency. Furthermore, under normal conditions only one of the two reactors would be removed from service at any given time, to allow the operating unit to be the primary backup power source for the non-operating unit. Removing both units from service will also eliminate this redundancy and will increase the Quad Cities' reliance on off-site power to support safety related systems. With both units offline and unable to immediately return to service, the power that Quad Cities could generate as a result of the requested provisional variance would not be available to support the voltage requirements that could occur under changing grid conditions. As of July 11, 2012, PJM grid status does not currently have or project any alerts, warnings, or actions. PJM predicts an anticipated Peak Load >146, 000 MW on Tuesday, July 17, 2012.

Assessment of Environmental Impacts Quad Cities has provided details on the environmental impact during the requested variance extension period from July 15, 2012, through July 25, 2012. Quad Cities has determined that there should not be any significant environmental impact during the course of this extension.

Quad Cities states that there has been no biological harm to the environment as a result of provisional variance IEPA-12-19 issued to Quad Cities Station on July 3, 2012, and effective July 7, 2012 through July 15, 2012.

Alternatives to Requested Relief Based on river temperatures recorded so far this summer and long range weather projections for the balance of the season, it is likely that there will be a number of extended periods during which ambient river temperatures will be at or above these limits. As previously explained, neither the option of derating the units nor of obtaining additional temporary cooling capacity will allow Quad Cities to maintain compliance if the ambient river temperatures exceed the applicable temperature limits. The only option is for Quad Cities to shut down once the ambient river temperatures are at or exceed the NPDES permit monthly limit.

In 2006, Quad Cities investigated the feasibility of installing cooling towers. Exelon states that based on analytical evaluation of historical plant, river, and meteorological data, the proposed towers performance and the resulting reduction in downstream river temperature could be quantified. When Exelon evaluated the actual days when excursion hours occurred in the last six year period (2000-2005), it found there was no appreciable reduction in the number of days when excursion hours would have occurred with the cooling towers in operation. According to Exelon, the reason for this is the high upstream river temperatures experienced on most of the days when actual excursion hours were recorded. For -80% of the days when excursion hours were recorded, the plant intake temperature was at the permit limited temperature or above

(>86'F), and for the remaining 20% of the days, the intake temperature was within half a degree of the permit limits. For most of these occurrences, even if adequate cooling tower capacity was in operation to achieve a zero thermal impact on the river (i.e., the plant discharge temperature equaled the intake temperature), excursion hours nonetheless would have been recorded.

Estimated cost in 2006 for installation of cooling towers ranged from $48 to $61 million.

Agency Determinations The Agency has reviewed the requested provisional variance and has concluded the following:

1.

Any environmental impact from the requested relief shall be closely monitored and the Agency shall be immediately notified of any adverse impacts.

2.

No reasonable alternatives appear available;

3.

No public water supplies should be affected;

4.

No federal regulations will preclude the granting of this request; and

5.

Quad Cities will face an arbitrary and unreasonable hardship if the request is not granted.

Conditions The Agency hereby GRANTS Quad Cities a provisional variance extension from Special Condition 7B of NPDES Permit No. IL0005037, subject to the following conditions:

A.

The term of this provisional variance extension goes through July 25, 2012. This provisional variance is granted based on the facts and circumstances described in the request for an extension, dated July 12, 2012, including consecutive days of abnormally high temperatures at Quad Cities, and high water temperatures in the Mississippi River. If the facts or circumstances described in the July 12, 2012 request for a provisional variance extension, the term of this provisional variance extension will end.

B.

Quad Cities shall provide the best operation of its station to produce the best effluent possible at all times. At no time, during the variance period, shall Quad Cities cause water temperature in the Mississippi River (beyond the mixing zone) to exceed 91 F or 20 F above ambient river temperature, whatever is greater.

C.

During the variance period, Quad Cities must continuously monitor intake, discharge and receiving water temperatures and visually inspect intake and discharge areas at least three times daily to assess any mortalities to fish and other aquatic life.

D.

Quad Cities shall document environmental conditions during the term of the provisional variance, including the activities described in C. above of this Section, and submit the documentation to the Agency and the Department of Natural Resources within 30 days after the provisional variance expires.

E.

Quad Cities shall immediately notify the Agency and the Department of Natural Resources of any unusual conditions, including mortalities to fish or other aquatic life; immediately take action to remedy the problem; investigate and document the cause and seriousness of the unusual conditions while providing updates to the Agency and the Department of Natural Resources as changes occur until normal conditions return; notify the Agency and the Department of Natural Resources when normal conditions return; and submit the documentation to the Agency and the Department of Natural Resources within 30 days after normal conditions return.

F.

Quad Cities shall develop and implement a response and recovery plan to address any adverse environmental impact due to thermal conditions resulting from the provisional variance, including loss and damage to aquatic life.

G.

Quad Cities shall notify Roger Callaway of the Agency by telephone at 217/782-9720 when the discharge specified in this provisional variance extension begins and again

when it ends. Written confirmation of each notice shall be sent within five days to the following address:

Illinois Environmental Protection Agency Bureau of Water - Water Pollution Control Attention: Roger Callaway 1021 North Grand Avenue East, MC # 19 Springfield, Illinois 62794-9276 H.

Quad Cities shall sign a certificate of acceptance of this provisional variance extension and forward that certificate to Roger Callaway at the address indicated above within one day of the date of the provisional variance extension. The certification should take the following form:

I (We)

, hereby accept and agree to be bound by all terms and conditions of the provisional variance granted by the Agency in dated Petitioner Authorized Agent Title Date Quad Cities shall continue to monitor and maintain compliance with all other parameters and conditions specified in its NPDES Permit No. IL0005037 Conclusion The Agency grants this provisional variance in accordance with its authority contained in Sections 35(b), 36 (c), and 37(b) of the Illinois Environmental Protection Act (415 ILCS 5/35(b),

36(c), and 37(b) (2010). The decision to grant this provisional variance is not intended to address compliance with any other applicable laws or regulations.

ftulie Armitage IActing Chief Legal Counsel

Exeln.

Exelon Generation Company, LLC www.exeloncorp.com Quad Cities Nuclear Power Station Nuclear 22710 206th Avenue North Cordova, I L 61242-9740 SVP-12-073 July 12, 2012 Mr. Roger Callaway (CAS-1 9)

Wastewater Compliance Unit Manager Illinois Environmental Protection Agency Bureau of Water Compliance Assurance Section #19 1021 North Grand Avenue East P.O. Box 19276 Springfield, Illinois 62794-9274 Re:

Quad Cities Nuclear Power Station NPDES Permit No. IL0005037 Provisional Variance IEPA-12-19 Extension Request-Emergency Application

Dear Mr. Callaway:

Thank you for the time, consideration and attention IEPA dedicated to Exelon's provisional variance extension request. We sincerely appreciate all of your efforts.

Below is Quad Cities Station's Certificate of Acceptance of the Provisional Variance Extension Order issued by IEPA in this matter.

Very Truly Yours, Tim Hanley Site Vice President Quad Cities Station TH/MS/sjo CC: Mark Stuhlman John Petro Letterbook

Certificate of Acceptance I(We), Tim Hanley, hereby accept and agree to be bound by all terms and conditions of the provisional variance extension granted by the Agency in matter IEPA 12-19 (provisional variance extension) dated July 12, 2012.

Exelon Generation Co. L.L.C/Quad Cities Station Petitioner Authorized Agent Site Vice President Title 07/12/2012 Date

Enclosure B Provisional Variance Extension Request (July 19, 2012) and Approval

Exeln.

Exelon Generation Company, LLC www.exeloncorp.com Nuclear Quad Cities Nuclear Power Station 22710 2o6th Avenue North Cordova, IL 61242-9740 SVP-12-077 July 19, 2012 Mr. Roger Callaway (CAS-19)

Wastewater Compliance Unit Manager Illinois Environmental Protection Agency Bureau of Water Compliance Assurance Section #19 1021 North Grand Avenue East P.O. Box 19276 Springfield, Illinois 62794-9274

Subject:

Quad Cities Nuclear Power Station NPDES Permit No. IL0005037 Provisional Variance 12-19 Extension Request - Emergency Application

Dear Mr. Callaway:

Exelon Generation Company, L.L.C. ("Exelon") hereby requests that the Illinois Environmental Protection Agency ("IEPA" or "Agency") grant an extension to provisional variance IEPA-12-19 issued on July 2, 2012 for Quad Cities Nuclear Power Station

("Quad Cities", "Station", or "Facility"), pursuant to Section 35(b) of the Environmental Protection Act ("Act") 415 ILCS 5/35. Exelon submits this Application for a provisional variance extension consistent with IEPA procedures at 35 Illinois Administrate Code 104.300. The Station discharges wastewater pursuant to NPDES Permit No.

IL0005037, which IEPA issued on August 26, 2010 with expiration date of August 31, 2015. Exelon requests the provisional variance be extended 14 days for Quad Cities Station allowing the station to exceed the non-excursion hour temperature limit for July/August of 86°F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of July 26, 2012 through August 8, 2012 by no more than 50F (91°F for July/August) or 2°F above ambient river temperature, whichever is greater. There has been no biological harm to the environment as a result of provisional variance IEPA 19 issued to Quad Cities Station on July 3, 2012 and effective July 5, 2012 through July 15, 2012. Also, there has been no biological harm to the environment documented as a result of the first extension granted to provisional variance IEPA-12-19 on July 12, 2012 and effective July 16, 2012 through July 25, 2012.

Backgqround Quad Cities Station is a base load nuclear-fueled steam electric generating facility located near Cordova, Illinois, on the Mississippi River at River Mile 506.8. The station operates two boiling water reactors which have a combined maximum generating capacity of 5,914 megawatts thermal. The station is currently operating at 100%

capacity. The station's capacity factor January 1, 2012 through June 30, 2012 was 90%. Quad Cities Station generation output is transmitted to the PJM Interconnection Grid. PJM Interconnection is a regional transmission organization (RTO) that coordinates the movement of wholesale electricity in all or parts of Delaware, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and the District of Columbia.

Circulating water used to cool and condense the steam from the generating process is withdrawn from, and discharged to, the Mississippi River (Receiving Stream Water ID-ILM-02). The current Mississippi River flow is 49,000 cfs and the 7Q1 0 is 13,700 cfs.

The incoming water is currently listed as impaired (2012 listing) due to Mercury, Polychlorinated biphenyls, and Manganese. These impaired waters have a designated use of public and food processing water as well as fish consumptions.

Quad Cities operates a condenser cooling water system in open cycle mode. In this mode, cooling water is drawn from the Mississippi River into an intake canal, passes through the plant systems, and is discharged through diffusers into the Mississippi River. The maximum design flow is 2,253 cfs or 1,011,000 gpm. The maximum temperature rise of the station from intake to effluent is 28°F at design flow of 2,253 cfs.

Open cycle operation with the diffusers was initially permitted by the IEPA on December 22, 1983. Quad Cities Station effluent temperature rise downstream of the diffusers at the edge of the mixing zone is limited to 50F per Special Condition 7(a) of NPDES Permit No. IL0005037.

Temperature monitoring data shows that the Mississippi River water temperature at the station's intake exceeded the non-excursion hour July temperature standard of 860 F on July 5, 2012 and remained above 86 0F through July 10, 2012. The Mississippi River water temperature at the station's intake exceeded 86°F again on July 16, 2012 and remains above 86 0F. Based on current weather forecast of daily maximum air temperatures in the 90's°F through July 27, ambient Mississippi River water temperature at the station's intake will remain near or above the non-excursion hour July temperature standard of 86°F. Mississippi River flow is currently 49,000 cfs and forecast to decrease to 35,000 cfs by July 25, 2012. The maximum Mississippi River ambient temperature the station will be able to comply with during the provisional variance period without the use of excursion hours is 84°F.

As a consequence of the unusually warm weather, high ambient river temperatures, and the absence of cooling during the evening hours, the capacity of the Mississippi River to

dissipate heat has been reduced beyond its normal capabilities. At current flow rate of 49,000 cfs, the river is not cooling off during the evening hours as is typical this time of year. Without nighttime cooling, the river retains the heat introduced to it during the daytime hours, both upstream and downstream of the station.

At no time has the difference between ambient river temperature and the temperature at the edge of the mixing zone exceeded 5 degree F. In fact, based on modeling, the difference between ambient river temperature and the temperature at the edge of the mixing zone has not exceeded 2 degrees F.

Relief Requested A provisional variance extension is being requested from the restriction in Special Condition 7B of the NPDES Permit that limits the number of excursion hours to 1 %

(87.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />) of the hours in a 12-month period ending with any month. Specifically, Special Condition 7B provides that the Station shall not cause water temperatures in the Mississippi River (beyond the mixing zone) to exceed by more than 30F the non-excursion hour temperature limit for July/August of 86 0F.

Exelon requests an extension to provisional variance IEPA-12-19 be issued to Quad Cities Station allowing the station to exceed the non-excursion hour temperature limit for July/August of 860F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of July 26, 2012 through August 8, 2012 by no more than 50F (91 OF for July/August) or 20F above ambient river temperature, whichever is greater.

Necessity for Request When the ambient river temperatures approach or exceed the non-excursion hour limits, the Station has no option other than to use excursion hours, and once its allotment of excursion hours is depleted, the Station must cease operating altogether to maintain compliance with the NPDES Permit. Partial deratings or adding cooling facilities (such as cooling towers) will not allow the Station to achieve compliance with a limit that already is exceeded even before any heat is added as a result of Station operations.

Special Condition 7B of NPDES Permit limits the temperature at the edge of the mixing zone to 86 0F in July/August, except when the Station is using excursion hours, during which time the temperatures at the edge of the mixing zone may be 3°F warmer than these limits. As a rule, Quad Cities has been able to operate well within its permitted thermal limits due to the fact that the ambient temperatures of the River (measured upstream of the discharge) generally remain below the non-excursion hour limit. It is only during periods when the ambient river temperatures are very close to or exceed the non-excursion hour limits or during periods of extreme low flows that the Station is forced to use a significant number of its excursion hour allowance.

In 2012 Quad Cities Station first began using excursion hours on Sunday, March 1 8 th when upstream Mississippi River temperature matched the station's effluent limitation of

570F. The permitted excursion hours were subsequently exhausted in March as a result of continued record breaking warm weather recorded throughout the mid-western states. Quad Cities Station submitted a request to IEPA on March 20, 2012 for relief from Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of March 21, 2012 to April 1,2012. IEPA subsequently issued Provisional Variance IEPA 12-11 to Quad Cities Station on March 21, 2012 allowing the station to exceed the non-excursion hour temperature limit for March of 57°F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of March 21, 2012 to April 1, 2012 by no more than 5°F (62°F for March) or 2°F above ambient river temperature, whichever is greater. A total of 223.5 excursion hours were accumulated by Quad Cities Station during March of 2012.

Quad Cities Station submitted a 2 nd request to IEPA on May 24, 2012 for relief from Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of May 26, 2012 thru May 29, 2012. IEPA subsequently issued Provisional Variance IEPA 12-17 to Quad Cities Station on May 25, 2012 allowing the station to exceed the non-excursion hour temperature limit for May of 78 0F stated in Special Condition 7(b) of NPDES Permit No.

IL0005037 for the period of May 26, 2012 thru May 29, 2012 by no more than 50F (78 0F for May) or 20F above ambient river temperature, whichever is greater. During the May Provisional Variance period, the station did not exceed the station's effluent limitation of 780F.

As you are aware, Illinois and the Upper Mississippi River basin are experiencing a long stretch of hot weather which is resulting in high ambient river temperatures. On July 1, 2012, 33 excursion hours became available when the 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> accumulated during July 2011 rolled off the rolling 12 month calendar. Quad Cities Station submitted a 3rd provisional variance request to IEPA on July 3, 2012 for relief from Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of July 5, 2012 thru July 15, 2012.

IEPA subsequently issued Provisional Variance IEPA 12-19 to Quad Cities Station on July 3, 2012 allowing the station to exceed the non-excursion hour temperature limit for July of 86 0F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of July 5, 2012 thru July 15, 2012 by no more than 50F (91'F for July) or 20F above ambient river temperature, whichever is greater. The PV went into effect when stations remaining 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> of the rolling 12 month calendar were exhausted. The stations downstream receiving stream exceeded the non-excursion hour temperature limit for July of 86 0F on July 5, 2012 @ 16:00 when upstream Mississippi River temperature reached 86 0F. PV IEPA-12-19 became effective July 7, 2012 @ 01:00 when the remaining 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> of the rolling 12 month calendar were exhausted. The stations downstream receiving stream remained above 86 0F until 00:00 on July 11, 2012 when the upstream Mississippi River temperature dropped back down to 85 0F. A total of 128 excursion hours have been accumulated by Quad Cities Station since IEPA-12-19 was issued. During the period of July 5, 2012 thru July 12, 2012, the maximum upstream Mississippi River temperature measured was 88 0F. The maximum downstream receiving stream temperature measured was 89 0F.

Quad Cities Station submitted a request for extension of provisional variance IEPA 19 to IEPA on July 12, 2012 for relief from Special Condition 7(b) of NPDES Permit No.

IL0005037 for the period of July 16, 2012 thru July 25, 2012. IEPA subsequently issued an extension of Provisional Variance IEPA 12-19 to Quad Cities Station on July 12, 2012 allowing the station to exceed the non-excursion hour temperature limit for July of 86 0F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of July 16, 2012 thru July 25, 2012 by no more than 50F (91OF for July) or 2°F above ambient river temperature, whichever is greater. The stations downstream receiving stream exceeded the non-excursion hour temperature limit for July of 86°F again on July 16, 2012 @ 11:00 when upstream Mississippi River temperature reached 86°F and remains above 86°F. During the period of July 16, 2012 thru July 18, 2012, the maximum upstream Mississippi River temperature measured was 86°F. The maximum downstream receiving stream temperature measured was 87 0F.

IEPA also issued Provisional Variances to Exelon's Braidwood Station (IEPA-1 2-12),

Dresden Station (IEPA-12-14), and LaSalle Station (IEPA-12-15) for thermal effluent relief during the March 2012 heat wave. IEPA issued a Provisional Variances to Dresden Station on July 6, 2012 (IEPA-12-22) and July 17, 2012 (IEPA-12-23).

With the current forecast, it is expected that Quad Cities Station will exceed the non-excursion hour temperature limit for July/August of 86°F periodically thru August 8, 2012 in order to continue to provide safe reliable power to the grid.

Based on current weather forecasts it is expected that the Mississippi River temperature at the station's intake will remain near or exceed the station's July/August permitted effluent limitation of 86 0F. Therefore, unless relief is granted by way of this provisional variance extension request, it is likely that the Station will be forced to shut down for correspondingly significant durations.

Since derating the units will not ensure compliance with the effluent limitations shutting the units down may be the only alternative. Removing both units from operation will not only reduce the available power supply to the grid but will also result in the need for power from the grid to operate key nuclear safety systems. The time required to return nuclear generating units to full power can require 18-24 hours meaning the electricity generated from these systems will not be readily available in the event of an emergency. Furthermore, under normal conditions only one of the two reactors would be removed from service at any given time allowing the operating unit to be the primary backup power source for the non-operating unit. Removing both units from service will also eliminate this redundancy and will increase the stations' reliance on off-site power to support safety related systems. With both unit's offline, and unable to immediately return to service, the power that Quad Cities Station could generate as a result of the requested provisional variance would not be available to support the voltage requirements that could occur under changing grid conditions. As of July 18, 2012, PJM has issued a Max Emergency Generation Alert for the Mid Atlantic Zone of the PJM RTO for day/evening periods of 7/18/2012. There are no forward looking

Alerts/Warnings/Actions posted by PJM as of 7/18/2012. PJM predicts an anticipated Peak Load >147,000 MW on Tuesday 7/23/2012.

In cooperation with IEPA's request that Exelon explore long-term thermal relief options for Quad Cities, Exelon commissioned extensive studies of the Station's thermal output and impacts. Exelon has shared those studies and its draft long-term regulatory relief proposal with both Federal and State regulators. Additionally, Quad Cities Station submitted a draft of its 316(a) thermal report which demonstrates no harm to indigenous aquatic populations to the IEPA, obtained comments, revised the report and then resubmitted the document for the Agency's final review and comment. At this time, the Agency's technical review of the Draft 316 (a) Report is nearing completion. Exelon is working on finalizing the Draft Adjusted Thermal Standard (ATS) petition to the Illinois Pollution Control Board (IPCB) which was submitted to the Agency for their internal review on July 5, 2012.

Assessment of Environmental Impacts The biological structure and condition of the receiving water has been well documented due to the ongoing Quad Cities Station Long-term Monitoring Program which began in 1971. This data is annually presented to ILEPA as well as other stakeholders throughout the state. No adverse effects to the local fish or mussel populations have been observed from similar requests in the past. Therefore, no adverse effects are anticipated with this thermal discharge provisional variance. The station recently completed a draft 316(a) demonstration that the agency has in its possession.

Because Quad Cities Station is not proposing to increase cooling water flows or increase the temperature of cooling water discharges, there will be no increase in impingement or entrainment as a result of the issuance of the requested Provisional Variance. Additionally, because the ambient river temperature increase has been gradual, resident fish species have either acclimated to the higher temperature or have found thermal refuge. In addition, forecast flows afford a delta T of approximate 2°F between the upstream and downstream temperatures. Therefore, resident fish species will not be subject to any heat shock as a result of increasing the allotment of excursion hours for Quad Cities Station.

The biological studies undertaken as part of Exelon's above-mentioned investigation of long-term, permanent relief options considered the effects on species of fish and shellfish that could result from increasing the number of excursion hours available to the plant. These studies support the conclusion that granting the requested Provisional Variance will not cause significant or unacceptable adverse effects to these species.

Species of fish that are likely to suffer from being exposed to temperatures in the excursion zone (i.e. up to 50F above the monthly standard) will already have taken refuge from the higher than normal ambient river temperatures. In 2006, a species specific die-off occurred in the incoming and receiving water during an elevated water temperature period. That specific incident continued to be captured in the QC Station dataset for several weeks after the first record. The die-off was the result of

temperatures increasing at a rate in excess of the mooneyes adaption capabilities. No fish kills have occurred as a result of the station discharge. Therefore, no fish mortality should result from operations authorized by the Provisional Variance. Due to the current flows, this situation is not anticipated.

This provisional variance request is due to the elevated temperature of the incoming water, not temperature differential; therefore, avoidance behavior outside the mixing zone is not anticipated because adequate flows are occurring for a minimal temperature differential.

Shellfish do not have similar thermal avoidance capabilities. However, the recently conducted biological studies show that the mussel (unionid) species in beds that are closest to the plant's discharge are generally more temperature tolerant, and are capable of surviving relatively short-term elevated thermal exposures. Species thought to be less thermally-tolerant inhabit beds located further downstream, in the Cordova Bed, located about 1 mile downstream from the plant. However, because the considerable distance between the plant to the Cordova and the flow characteristics of the River (that cause much of the plant's thermal discharge to avoid the Cordova Bed) the Provisional Variance should not cause any appreciable harm to mussel species downstream of the plant.

If the variance is granted, the station will monitor the waters upstream, near the intake, and downstream for detrimental effects to the fishery as noted in previous provisional variances. Visual inspections will take place 3 times during the day and if necessary, a complete visual and water quality assessment will take place in the late afternoon of each day at prescribed areas up and downstream of the plant. This will only take place if any evidence of fish mortality is currently occurring or has occurred. The station fishery biologist will be responsible for this assessment with consultation with the local governing agencies, if necessary. Late afternoon is when the potential effects would be most noticeable, but assessments will occur at the first sign of an issue. Our current biological program will capture and short-term and long-term effects of a provisional variance.

Alternatives to Requested Relief Historically, Quad Cities Station has used excursion hours during periods of extreme heat and low-river flows. Due in part to the mixing capacity provided by the Mississippi River, and the fact that ambient river temperatures rarely exceed the non-excursion hour NPDES Permit limits, only a relatively small percentage of the permitted excursion hours typically are used to cover any one of these periods. Unless a provisional variance extension is issued, the Station will have to shut down during all times that the ambient river temperatures are at or above the non-excursion hour limit after July 25, 2012. Based on river temperatures recorded so far this summer and long range weather projections for the balance of the season, it is likely that there will be a number of extended periods during which ambient river temperatures will be at or above these limits. As previously explained, neither the option of derating the units nor of obtaining

additional temporary cooling capacity will allow the Station to maintain compliance if the ambient river temperatures exceed the applicable temperature limits. The only option is for the Station to shut down once the ambient River temperatures are at or exceed the NPDES permit monthly limit.

In 2006, the station investigated the feasibility of installing cooling towers. Based on analytical evaluation of historical plant, river, and meteorological data, the proposed towers performance and the resulting reduction in downstream river temperature could be quantified. When the actual days when excursion hours occurred in the last six year period (2000-2005) were evaluated, there was no appreciable reduction in the number of days when excursion hours would have occurred with the cooling towers in operation.

The reason for this is the high upstream river temperatures experienced on most of the days when actual excursion hours were recorded. For -80% of the days when excursion hours were recorded, the plant intake temperature was at the permit limited temperature or above L>86 0F), and for the remaining 20% of the days, the intake temperature was within half a degree of the permit limits. For most of these occurrences, even if adequate cooling tower capacity was in operation to achieve a zero thermal impact on the river (i.e., the plant discharge temperature equaled the intake temperature), excursion hours nonetheless would have been recorded. Estimated cost in 2006 for installation of cooling towers ranged from $48 to $61 million.

Mitiqative Actions to be Taken Durinq the Variance Period During the period when the Station uses any additional excursion hours authorized by the requested provisional variance, Quad Cities Station will do the following: (1) continuously monitor the intake and discharge temperatures and assess water temperatures at the edge of the mixing zone using the NPDES Permit temperature monitoring curve or field measurements; (2) on a daily basis, inspect the intake and discharge areas to assess any mortalities to aquatic life, and report the results of these monitoring activities to the Agency within 30 days of the expiration of the provisional variance (or such other time as agreed upon by the Agency); and (3) notify the Agency of any significant adverse environmental conditions observed that might be caused by operations authorized by the provisional variance, including mortalities to fish or other aquatic life, investigate the cause of such conditions, provide the Agency updates regarding the situation, including when normal conditions return, and submit a report to the Agency regarding these matters within 30 days of the expiration of the provisional variance period (or such other time as agreed upon by the Agency).

Summary Exelon requests that an extension to provisional variance IEPA-12-19 be issued to Quad Cities Station allowing the station to exceed the non-excursion hour temperature limit for July/August of 86 0F stated in Special Condition 7(b) of NPDES Permit No.

IL0005037 for the period of July 26, 2012 through August 8, 2012 by no more than 50F (91 OF for July) or 20F above ambient river temperature, whichever is greater.

If you should have any questions regarding these matters, please feel free to contact Vicki Neels at (309) 227-3200 or Mark Stuhlman at (309) 227-2765 from Quad Cities or John Petro, Principal Environmental Analyst, Exelon Generation at (630) 657-3209.

Very Truly Yours, Tim Hanley Site Vice President Quad Cities Station TH/MS/sjo CC: Mark Stuhlman John Petro Letterbook

ILLINOIS ENVIRONMENTAL PROTECTION AGENCY July 24, 2012 Exelon Generation Company, L.L.C.

)

Quad Cities Nuclear Power Station

))

Petitioner,

))

v.

)

IEPA-12-19

)

(Provisional Variance Extension-Water)

ILLINOIS ENVIRONMENTAL

)

PROTECTION AGENCY,

))

Respondent.

)

Re:

Provisional Variance Extension From Discharge Limits Contained in NPDES Permit IL0005037

Dear Mr. Hanley:

On July 3, 2012, the Illinois Environmental Protection Agency (Agency) granted a request from Exelon Generation Company, L.L.C.'s Quad Cities Nuclear Power Station (Quad Cities) for a provisional variance (IEPA-12-19). This provisional variance was to end no later than July 15, 2012. On Julyl2, 2012, the Agency granted an extension of the provisional variance through July 25, 2012.

On July, 19, 2012, Quad Cities requested a second extension (Attachment A). Quad Cities requests that the terms and conditions of this provisional variance from thermal limits in NPDES Permit IL0005037 (Attachment B) be extended a second time, so that Quad Cities can continue operating through this unusually hot and dry period of weather and resulting high river temperatures.

The Agency has completed its technical review of the attached July 19, 2012 request for another extension of this provisional variance. Quad Cities is seeking a second provisional variance extension from July 26, 2012, through August 8, 2012, to allow it to exceed the maximum temperature limit in Special Condition 7B of NPDES Permit IL0005037 by no more than 50 (91' for July and August), or 20 above ambient river temperature, whichever is greater.

Based on its review, the Agency GRANTS Quad Cities a provisional variance extension subject to the specific conditions set forth below.

=

Background===

Quad Cities is a base load nuclear-fueled steam electric generating facility located near Cordova, Illinois, on the Mississippi River at River Mile 506.8. The station operates two boiling water reactors which have a combined maximum generating capacity of 5,914 megawatts thermal. The station is currently operating at 100% capacity. The station's capacity factor January 1, 2012 through June 30, 2012 was 90%. Quad Cities generation output is transmitted to the PJM Interconnection Grid. PJM Interconnection is a regional transmission organization (RTO) that coordinates the movement of wholesale electricity in all or parts of Delaware, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and the District of Columbia.

Circulating water used to cool and condense the steam from the generating process is withdrawn from-, and discharged to, the Mississippi River (Receiving Stream Water ID-IL M-02. The incoming water is currently listed as impaired (2012 listing) due to Mercury, Polychlorinated biphenyls, and Manganese. These impaired waters have a designated use of public and food processing water as well as fish consumptions.

Quad Cities operates a condenser cooling water system in open cycle mode. In this mode, cooling water is drawn from the Mississippi River into an intake canal, passes through the plant systems, and is discharged through diffusers into the Mississippi River. The maximum design flow is 2,253 cfs. or 1,011,000 gpm. The maximum temperature rise of the station from intake to effluent is 28°F at design flow of 2,253 cfs. Open cycle operation with the diffusers was initially permitted by the Agency on December 22, 1983.

Special Condition 7B of NPDES Permit IL00005037 (Attachment B) limits the temperature at the edge of the mixing zone to 86°F in July and August, except when Quad Cities is using excursion hours, during which time the temperatures at the edge of the mixing zone may be 31F warmer than these limits.

Temperature monitoring data shows that the Mississippi River water temperature at the Quad Cities' intake exceeded the non-excursion hour July temperature standard of 86°F on July 5, 2012, and remained above 861F through July 10, 2012. The Mississippi River water temperature at Quad Cities' intake exceeded 86°F again on July 16, 2012, and remains above 86°F. Based on current weather forecast of daily maximum air temperatures in the 90's°F through July 27, ambient Mississippi River water temperature at Quad Cities' intake will remain near or above the non-excursion hour July and August temperature standard of 86°F. Mississippi River flow is currently 49,000 cfs and forecast to decrease to 35,000 cfs by July 25, 2012. The maximum Mississippi River ambient temperature that Quad Cities will be able to comply with during the provisional variance period without the use of excursion hours is 841F.

As a consequence of the unusually warm weather, high ambient river temperatures, and the absence of cooling during the evening hours, the capacity of the Mississippi River to dissipate heat has been reduced beyond its normal capabilities. At current flow rates of 49,000 efs, the river is not cooling off during the evening hours as is typical this time of year. Without

nighttime cooling, the river retains the heat introduced to it during the daytime hours, both upstream and downstream of the station.

Quad Cities states that at no time has the difference between ambient river temperature and the temperature at the edge of the mixing zone exceeded 50 F. In fact, based on modeling, the difference between ambient river temperature and the temperature at the edge of the mixing zone has not exceeded 20 F.

In cooperation with the Agency's request that Exelon explore long-term thermal relief options for Quad Cities, Exelon commissioned extensive studies of Quad Cities' thermal output and impacts. Exelon has shared those studies and its draft long-term regulatory relief proposal with both Federal and State regulators. Additionally, Quad Cities submitted a draft of its 316(a) thermal report which demonstrates no harm to indigenous aquatic populations to the Agency, obtained comments, revised the report and then resubmitted the document for the Agency's final review and comment. At this time, the Agency's technical review of the Draft 316 (a) Report is nearing completion. Exelon is working on finalizing the Draft Adjusted Thermal Standard (ATS) petition to the Illinois Pollution Control Board (IPCB) which was submitted to the Agency for its internal review on July 5, 2012.

Relief Requested Condition 7B of the NPDES Permit limits the number of excursion hours to 1% (87.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />) of the hours in a 12-month period ending with any month. Specifically, Special Condition 7B provides that the Station shall not cause water temperatures in the Mississippi River (beyond the mixing zone) to exceed by more than 3°F the non-excursion hour temperature limit for July and August of 86°F.

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

FO 45 45 57 68 78 85 86 86 85 75 65 52 Quad Cities requests an extension to provisional variance IEPA-12-19 be issued to Quad Cities Station allowing the station to exceed the non-excursion hour temperature limit for July and August of 86°F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of July 26, 2012, through August 8, 2012, by no more than 5°F (91IF for July and August) or 21F above ambient river temperature, whichever is greater.

Necessity for Request In its request, Quad Cities states that when the ambient river temperatures approach or exceed the non-excursion hour limits, Quad Cities has no option other than to use excursion hours, and once its allotment of excursion hours is depleted, Quad Cities must cease operating altogether to maintain compliance with the NPDES Permit. According to Exelon, partial deratings or adding cooling facilities (such as cooling towers) will not allow Quad Cities to achieve compliance with a limit that already is exceeded even before M heat is added as a result of station operations.

Special Condition 7B of NPDES Permit limits the temperature at the edge of the mixing zone to 86'F in July and August, except when Quad Cities is using excursion hours, during which time the temperatures at the edge of the mixing zone may be 3YF warmer than these limits. As a rule, Quad Cities has been able to operate within its permitted thermal limits due to the fact that the ambient temperatures of the River (measured upstream of the discharge) generally remain below the non-excursion hour limit. It is only during periods when the ambient river temperatures are very close to or exceed the non-excursion hour limits or during periods of extreme low flows that Quad Cities uses its excursion hour allowance.

Illinois and the Upper Mississippi River basin are experiencing a long stretch of hot weather, which is resulting in high ambient river temperatures. In 2012 Quad Cities first began using excursion hours on Sunday, March 18th when upstream Mississippi River temperature matched the station's effluent limitation of 57°F. The permitted excursion hours were subsequently exhausted in March as a result of continued record breaking warm weather recorded throughout the mid-western states. Quad Cities submitted a request to the Agency on March 20, 2012, for relief from Special Condition 7(b) of NPDES Permit No. IL0005037, for the period of March 21, 2012, to April 1, 2012. The Agency subsequently issued Provisional Variance IEPA 12-11 to Quad Cities on March 21, 2012, allowing the station to exceed the non-excursion hour temperature limit for March of 571F stated in Special Condition 7(b) of NPDES Permit No.

IL0005037 for the period of March 21, 2012 to April 1, 2012 by no more than 5'F (62°F for March) or 2°F above ambient river temperature, whichever is greater. During March of 2012, Quad Cities accumulated a total of 223.5 excursion hours.

Quad Cities submitted a second request to the Agency on May 24, 2012, for relief from Special Condition 7(b) of NPDES Permit No. IL0005037, from May 26, 2012, through May 29, 2012.

The Agency subsequently issued Provisional Variance IEPA 12-17 to Quad Cities on May 25, 2012, allowing the station to exceed the non-excursion hour temperature limit for May of 78°F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of May 26, 2012, through May 29, 2012, by no more than 50F (781F for May) or 2°F above ambient river temperature, whichever is greater. During the May Provisional Variance period, Quad Cities did not exceed its effluent limitation of 78°F.

On July 1, 2012, 33 excursion hours became available when the 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> accumulated during July 2011 rolled off the rolling 12-month calendar. Quad Cities submitted a third provisional variance request to the Agency on July 3, 2012, seeking relief from Special Condition 7(b) of NPDES Permit No. IL0005037, from July 5, 2012, through July 15, 2012. The Agency issued Provisional Variance IEPA 12-19 to Quad Cities on July 3, 2012, allowing the station to exceed the non-excursion hour temperature limit for July of 867F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of July 5, 2012, through July 15, 2012, by no more than 5'F (91OF for July and August) or 2°F above ambient river temperature, whichever is greater.

Provisional Variance IEPA-12-19 went into effect when Quad Cities' remaining 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> of the rolling 12-month calendar were exhausted. Quad Cities downstream receiving stream exceeded the non-excursion hour temperature limit for July of 86'F on July 5, 2012, at 4pm when upstream Mississippi River temperature reached 861F. Provisional Variance IEPA-12-19 became

effective July 7, 2012, at lam when the remaining 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> of the rolling 12-month calendar were exhausted. Quad Cities' downstream receiving stream remained above 867F until 12am on July 11, 2012 when the upstream Mississippi River temperature dropped back down to 85'F.

Quad Cities has accumulated a total of 128 excursion hours since IEPA-12-19 was issued.

During the period of July 5, 2012, through July 12, 2012, the maximum upstream Mississippi River temperature measured was 88°F. The maximum downstream receiving stream temperature measured was 89'F.

Quad Cities submitted a request for extension of provisional variance IEPA-12-19 to the Agency on July 12, 2012, for relief from Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of July 16, 2012, thru July 25, 2012. The Agency subsequently issued an extension of Provisional Variance IEPA 12-19 to Quad Cities on July 12, 2012, allowing the station to exceed the non-excursion hour temperature limit for July of 86°F stated in Special Condition 7(b) of NPDES Permit No. IL0005037 for the period of July 16, 2012, thru July 25, 2012, by no more than 5°F (91°F for July) or 2°F above ambient river temperature, whichever is greater. Quad Cities' downstream receiving stream exceeded the non-excursion hour temperature limit for July of 86°F again on July 16, 2012 @ 11:00 am when upstream Mississippi River temperature reached 860F and remains above 86°F. During the period of July 16, 2012, through July 18, 2012, the maximum upstream Mississippi River temperature measured was 86°F. The maximum downstream receiving stream temperature measured was 870F.

The Agency also issued Provisional Variances to Exelon's Braidwood Station (IEPA-12-12),

Dresden Station (IEPA-12-14), and LaSalle Station (IEPA-12-15) for thermal effluent relief during the March 2012 heat wave. In addition, the Agency issued a Provisional Variance to Dresden Station on July 6, 2012 (IEPA-12-14) and also on July 18, 2012 (IEPA 12-23). On July 19, 2012, the Agency issued a second provisional variance to LaSalle Station (IEPA 12-24).

With the current forecast, Quad Cities says it expects to exceed the non-excursion hour temperature limit for July and August of 86°F periodically through August 8, 2012, if it is to be able to continue to provide safe reliable power to the grid.

Based on current weather forecasts it is expected that the Mississippi River will approach or exceed Quad Cities' permitted effluent limitation. Therefore, unless relief is granted by way of this provisional variance extension request, Quad Cities states that will be forced to shut down for correspondingly significant durations.

Because derating the units will not ensure compliance with the effluent limitations, Quad Cities says that shutting the units down may be the only alternative. Removing both units from operation will not only reduce the available power supply to the grid but will also result in the need for power from the grid to operate key nuclear safety systems. The time required to return nuclear generating units to full power can require 18-24 hours, meaning the electricity generated from these systems will not be readily available in the event of an emergency. Furthermore, under normal conditions only one of the two reactors would be removed from service at any given time, to allow the operating unit to be the primary backup power source for the non-operating unit. Removing both units from service will also eliminate this redundancy and will

increase the Quad Cities' reliance on off-site power to support safety related systems. With both units offline and unable to immediately return to service, the power that Quad Cities could generate as a result of the requested provisional variance would not be available to support the voltage requirements that could occur under changing grid conditions. As of July 18, 2012, PJM has issued a Max Emergency Generation Alert for the Mid Atlantic Zone of the PJM RTO for the day/evening periods of July 17, 2012. There are no forward looking Alerts/ Warnings/

Actions posted by PMJ as of July 18, 2012. PMJ predicts an anticipated Peak Load >147,000 MW on Tuesday, July 23.

Assessment of Environmental Impacts Quad Cities has provided details on the environmental impact during the requested variance extension period from July 26, 2012, through August 8, 2012. Quad Cities has determined that there should not be any significant environmental impact during the course of this extension.

Quad Cities states that there has been no biological harm to the environment as a result of the first extension to provisional variance IEPA-12-19 issued to Quad Cities Station on July 12, 2012, and effective July 16, 2012, through July 25, 2012.

Alternatives to Requested Relief Based on river temperatures recorded so far this summer and long range weather projections for the balance of the season, it is likely that there will be a number of extended periods during which ambient river temperatures will be at or above these limits. As previously explained, neither the option of derating the units nor of obtaining additional temporary cooling capacity will allow Quad Cities to maintain compliance if the ambient river temperatures exceed the applicable temperature limits. The only option is for Quad Cities to shut down once the ambient river temperatures are at or exceed the NPDES permit monthly limit.

In 2006, Quad Cities investigated the feasibility of installing cooling towers. Exelon states that based on analytical evaluation of historical plant, river, and meteorological data, the proposed towers performance and the resulting reduction in downstream river temperature could be quantified. When Exelon evaluated the actual days when excursion hours occurred in the last six year period (2000-2005), it found there was no appreciable reduction in the number of days when excursion hours would have occurred with the cooling towers in operation. According to Exelon, the reason for this is the high upstream river temperatures experienced on most of the days when actual excursion hours were recorded. For -80% of the days when excursion hours were recorded, the plant intake temperature was at the permit limited temperature or above

(>867F), and for the remaining 20% of the days, the intake. temperature was within half a degree of the permit limits. For most of these occurrences, even if adequate cooling tower capacity was in operation to achieve a zero thermal impact on the river (i.e., the plant discharge temperature equaled the intake temperature), excursion hours nonetheless would have been recorded.

Estimated cost in 2006 for installation of cooling towers ranged from $48 to $61 million.

Agency Determinations The Agency has reviewed the requested provisional variance and has concluded the following:

1.

Any environmental impact from the requested relief shall be closely monitored and the Agency shall be immaediately notified of any adverse impacts.

2.

No reasonable alternatives appear available;

3.

No public water supplies should be affected;

4.

No federal regulations will preclude the granting of this request; and

5.

Quad Cities will face an arbitrary and unreasonable hardship if the request is not granted.

Conditions The Agency hereby GRANTS Quad Cities a second provisional variance extension from Special Condition 7B of NPDES Permit No. IL0005037, subject to the following conditions:

A.

The term of this second provisional variance extension goes through August 8, 2012. This extension is granted based on the facts and circumstances described in the request for an extension, dated July 19, 2012, including consecutive days of abnormally high temperatures at Quad Cities, and high water temperatures in the Mississippi River. If the facts or circumstances described in the July 19, 2012 request for a provisional variance extension abate before August 8, 2012, the term of this provisional variance extension will end.

B.

Quad Cities shall provide the best operation of its station to produce the best effluent possible at all times. At no time, during the variance period, shall Quad Cities cause water temperature in the Mississippi River (beyond the mixing zone) to exceed 91°F or 20 F above ambient river temperature, whatever is greater.

C.

During the variance period, Quad Cities must continuously monitor intake, discharge and receiving water temperatures and visually inspect intake and discharge areas at least three times daily to assess any mortalities to fish and other aquatic life.

D.

Quad Cities shall document environmental conditions during the term of the provisional variance, including the activities described in C. above of this Section, and submit the documentation to the Agency and the Department of Natural Resources within seven (7) days after the provisional variance expires.

E.

Quad Cities shall immediately notify the Agency and the Department of Natural Resources of any unusual conditions, including mortalities to fish or other aquatic life; immediately take action to remedy the problem; investigate and document the cause and seriousness of the unusual conditions while providing updates to the Agency and the Department of Natural Resources as changes occur until normal conditions return; notify

the Agency and the Department of Natural Resources when normal conditions return; and submit the documentation to the Agency and the Department of Natural Resources within 30 days after normal conditions return.

F.

Quad Cities shall develop and implement a response and recovery plan to address any adverse environmental impact due to thermal conditions resulting from the provisional variance, including loss and damage to aquatic life.

G.

Quad Cities shall notify Roger Callaway of the Agency by telephone at 217/782-9720 when the discharge specified in this provisional variance extension begins and again when it ends. Written confirmation of each notice shall be sent within five days to the following address:

Illinois Environmental Protection Agency Bureau of Water - Water Pollution Control Attention: Roger Callaway 1021 North Grand Avenue East, MC #19 Springfield, Illinois 62794-9276 H.

Quad Cities shall sign a certificate of acceptance of this provisional variance extension and forward that certificate to Roger Callaway at the address indicated above within one day of the date of the provisional variance extension. The certification should take the following form:

I (We)

, hereby accept and agree to be bound by all terms and conditions of the provisional variance granted by the Agency in dated Petitioner Authorized Agent Title Date Quad Cities shall continue to monitor and maintain compliance with all other parameters and conditions specified in its NPDES Permit No. IL0005037

Conclusion The Agency grants this provisional variance in accordance with its authority contained in Sections 35(b), 36 (c), and 37(b) of the Illinois Environmental Protection Act (415 ILCS 5/35(b),

36(c), and 37(b) (2010). The decision to grant this provisional variance is not intended to address compliance with any other applicable laws or regulations.

Sincerely,

'ju e It age-K-'Acting Chief Legal Counsel cc:

John Kim Julie Armitage Lisa Bonnet Sanjay Sofat Marcia WiUhite Chuck Gunnarson Roger Callaway Vera Herst

Exeln@

Exelon Generation Company, LLC wwwexeloncorp.com Quad Cities Nuclear Power Station Nucear 22710 2o6th Avenue North Cordova, IL 61242-9740 SVP-12-079 July 24, 2012 Mr. Roger Callaway (CAS-19)

Wastewater Compliance Unit Manager Illinois Environmental Protection Agency Bureau of Water Compliance Assurance Section #19 1021 North Grand Avenue East P.O. Box 19276 Springfield, Illinois 62794-9274 Re:

Quad Cities Nuclear Power Station NPDES Permit No. IL0005037 Provisional Variance IEPA-12-19 Extension Request - Emergency Application

Dear Mr. Callaway:

Thank you for the time, consideration and attention IEPA dedicated to Exelon's provisional variance extension request. We sincerely appreciate all of your efforts.

Below is Quad Cities Station's Certificate of Acceptance of the Provisional Variance Extension Order issued by IEPA in this matter.

Very Truly Yours, m

Hanl~ey*"

Site Vice President Quad Cities Station TH/MS/sjo CC: Mark Stuhlman John Petro Letterbook

Certificate of Acceptance I(We), Tim Hanley, hereby accept and agree to be bound by all terms and conditions of the provisional variance extension granted by the Agency in matter IEPA 12-19 (provisional variance extension) dated July 24, 2012.

Exelon Generation Co. L.L.C/Quad Cities Station Petitioner A thorized Agent Site Vice President Title 07/24/2012 Date