Text

License Amendment Request (LAR) to Revise Emergency Diesel Generator (EDG) Test Loads in Surveillance Requirement (SR) 3.8.1.3 and SR 3.8.1.9
	ML083110125
Person / Time
Site:	Prairie Island
Issue date:	11/04/2008
From:	Wadley M; Northern States Power Co, Xcel Energy
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	L-PI-08-080
	Download: ML083110125 (42)
	v • d • e

Xcel Energym L-PI-08-080 10 CFR 50.90 U S Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Prairie Island Nuclear Generating Plant Units 1 and 2 Dockets 50-282 and 50-306 License Nos. DPR-42 and DPR-60 License Amendment Request (LAR) to Revise Emeraencv Diesel Generator (EDG) Test Loads in Surveillance Requirement (SR) 3.8.1.3 and SR 3.8.1.9 Pursuant to 10 CFR 50.90, Northern States Power Company, a Minnesota corporation (NSPM), doing business as Xcel Energy, hereby requests an amendment to the Technical Specifications (TS) for the Prairie Island Nuclear Generating Plant (PINGP) to increase the 24 month test load for the Unit 1 EDGs, D l and D2, reduce the monthly test load for the Unit 2 EDGs, D5 and D6, and reduce the 24 month test loads for the Unit 2 EDGs. NSPM has evaluated the proposed changes in accordance with 10 CFR 50.92 and concluded that they involve no significant hazards consideration.

The proposed changes involve revision of the surveillance test loads required in Technical Specification (TS) 3.8.1, "AC Sources - Operating," Surveillance Requirement (SR) 3.8.1.3 and SR 3.8.1.9. This LAR proposes to revise SR 3.8.1.3 to require testing D5 and D6 monthly at or above 4000 kW to demonstrate TS operability.

In addition to the TS required monthly testing, NSPM will continue monthly testing at or above 90% of the EDG rated load to assist in early identification of degraded EDG capabilities which could prevent performance of their safety function. On a 24-month Frequency, SR 3.8.1.9 requires each EDG to be operated for at least 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of which at least 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months are performed within a defined high load range and the remainder at or above a defined lower load. This LAR proposes to revise SR 3.8.1.9 to require testing D l and D2 at or above 2500 kW for the remainder of its 24-hour test. SR 3.8.1.9 would also be revised to require testing D5 and D6 at or above 5400 kW for 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months and at or above 4000 kW for the remainder of the 24-hour test. The upper load limit for the 2-hour portion of the test would remain unchanged.

The enclosure to this letter contains the licensee's evaluation of the proposed changes.

NSPM requests approval of the proposed license amendment within one calendar year of the submittal date. Upon NRC approval, NSPM requests 90 days to implement the associated changes. In accordance with 10 CFR 50.91, a copy of this application, with enclosures, is being provided to the designated State of Minnesota Official.

1717 Wakonade Drive East Welch, Minnesota 55089-9642 Telephone: 651.388.1121

Document Control Desk Page 2 If there are any questions or if additional information is needed, please contact Mr. Dale Vincent, P.E., at 651-388-1121.

Summary of Commitments Upon approval by the NRC, NSPM will implement the following commitment with implementation of the monthly test load changes proposed in this LAR:

The Prairie Island Nuclear Generating Plant Unit 2 Emergency Diesel Generators (EDGs) will be tested at or above 90% of their rated load on a schedule consistent with SR 3.8.1.3. Abnormalities in EDG performance between the SR 3.8.1.3 test load and the rated load will be evaluated under NSPM's corrective action program, which incorporates trending capabilities, and corrected under the maintenance program.

This letter contains no revisions to existing commitments.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on NOV 0 4 2008

,~ud*

Michael D. Wadley Site Vice president, Prairie ~ s l a n ~ u c l e Generating ar Plant Units 1 and 2 Northern States Power Company - Minnesota

Enclosure:

Evaluation of Proposed Changes cc: Administrator, Region Ill, USNRC Project Manager, Prairie Island, USNRC Resident Inspector, Prairie Island, USNRC State of Minnesota

ENCLOSURE Evaluation of the Proposed Changes License Amendment Request (LAR) to Revise Emergency Diesel Generator (EDG)

Test Loads in Surveillance Requirement (SR) 3.8.1.3 and SR 3.8.1.9

1.

SUMMARY

DESCRIPTION

2. DETAILED DESCRIPTION 2.1 Proposed Changes

2.2 Background

3. TECHNICAL EVALUATION

4. REGULATORY SAFETY ANALYSIS 4.1 Applicable Regulatory Requirementslcriteria 4.2 Precedent 4.3 Significant Hazards Consideration 4.4 Conclusions

5. ENVIRONMENTAL CONSIDERATION

6. REFERENCES ATTACHMENTS:

1. Technical Specification Pages (Markup)

2. Bases Pages (Markup) (For information only)

3. Technical Specification Pages (Retyped)

Page 1 of 30

Enclosure NSPM EDG Test Loads

1.

SUMMARY

DESCRIPTION This LAR is a request to amend Operating Licenses DPR-42 and DPR-60 for the Prairie Island Nuclear Generating Plant (PINGP), Units 1 and 2.

Northern States Power Company, a Minnesota corporation, (NSPM) requests Nuclear Regulatory Commission (NRC) review and approval of proposed revisions to Technical Specification (TS) 3.8.1, "AC Sources-Operating," SR 3.8.1.3 and SR 3.8.1.9. The proposed SR 3.8.1.3 changes will reduce the TS required monthly test loading on the Unit 2 EDGs, D5 and D6, to a load which bounds the loading these EDGs are required to supply to perform their safety function. On a 24-month Frequency, SR 3.8.1.9 requires each EDG to be operated for at least 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of which at least 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months are performed within a defined high load range and the remainder at or above a defined lower load. The proposed SR 3.8.1.9 changes will increase the Unit 1 EDG, D l and D2, test load to be consistent with the monthly test load, reduce the lower load limit for the 2-hour portion of test on the Unit 2 EDGs to a loading which is greater than or equal to the continuous load rating of the EDGs, and reduce the remainder of the 24-hour test to the loading consistent with the proposed monthly test load. These tests will continue to adequately demonstrate operability of the EDGs. As part of the basis for reducing the SR 3.8.1.3 test loading, NSPM also proposes to continue testing of the Unit 2 EDGs at or above 90% of their rated loading on a schedule consistent with the performance Frequency for SR 3.8.1.3 and resolve any degradation through the corrective action and maintenance programs.

2. DETAILED DESCRIPTION 2.1 Proposed Changes A brief description of the associated proposed TS changes is provided below along with a discussion of the justification for each change. The specific wording changes to the TS are provided in Attachments 1 and 3 to this enclosure.

TS L C 0 3.8.1, "AC Sources - Operating", SR 3.8.1.3: Currently, SR 3.8.1.3 requires monthly testing of D5 and D6 monthly at loadings 2 5100 kW and 5 5300 kW. This LAR proposes to require monthly testing at loadings 4000 kW and remove the upper load limit. This proposed test loading is acceptable because it will demonstrate that these diesels are operable and capable of supplying the loads necessary to perform their safety functions.

TS L C 0 3.8.1, "AC Sources - Operating", SR 3.8.1.9: This SR requires operation of each EDG for 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months with two or more hours within a defined high test load range and the remainder of the test at or above a defined lower test load. Currently, SR 3.8.1.9 requires testing of D l and D2 at or above 2475 kW for the remainder portion of the 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . This LAR proposes to increase the Page 2 of 30

Enclosure NSPM EDG Test Loads load for this portion of the test to 2500 kW. This proposed test loading is acceptable because it will demonstrate that these diesels are operable and capable of supplying loads at or above their required service loads and is consistent with their monthly load.

Currently, SR 3.8.1.9 requires D5 and D6 at loadings 15562 kW and 15940 kW for the two hour portion of the test. This LAR proposes to require testing at loadings 2 5400 kW and 5 5940 kW for two or more hours. This proposed test loading is acceptable because it will demonstrate that these diesels are operable and capable of supplying loads at or above their required service loads and their full rated load.

This LAR proposes to revise the remainder portion of the D5 and D6 test load from at or above 4860 kW to at or above 4000 kW. This proposed test loading is acceptable because it will demonstrate that these diesels are operable and capable of supplying loads at or above their required service loads and is consistent with their monthly load.

Although Bases changes are not a part of this LAR, Attachment 2 to this enclosure includes marked up Bases pages for information. The changes proposed in are directly related to the changes proposed to TS 3.8.1.

2.2 Backqround Originally, the two PlNGP units were built with two EDGs, D l and D2, to supply the onsite power sources for the safeguards buses for both units. In the early 1990's in response to the station blackout (SBO) rule, 10CFR 50.63, "Loss of All Alternating Current Power", EDGs D5 and D6 were installed to supply the onsite power source for the Unit 2 safeguards buses.

Since D5 and D6 were placed into service in early 1993, they have experienced operating issues during some of their TS required surveillance tests, including monthly tests, which have resulted in engine shutdown by the plant operators prior to completion of the surveillance test. In April 2001, June 2004, April 2005, and October 2007, surveillance tests of D5 or D6 were suspended due to high engine crankcase pressure and corrective maintenance was commenced to replace suspect cylinder liners and associated engine components. In February 2006, following scheduled maintenance, D6 "return to service" testing was also suspended due to high crankcase pressure and corrective maintenance was commenced to replace suspect cylinder liners and associated engine components. Three of these events required shutdown of Unit 2 to perform the required corrective maintenance.

In all of these events, crankcase pressure has only been an issue at or near the rated load. Whenever the load has been reduced (to near 4000 kW) crankcase pressure has returned to normal operating values.

Page 3 of 30

Enclosure NSPM EDG Test Loads As discussed below, the required service loading of the Unit 2 EDGs is significantly less than their rating. Currently, SR 3.8.1.9 requires testing at loads between 103 to 110%

of their continuous rating, for at least 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months every 24 months. Operating EDGs D5 and D6 above 103% of their continuous rating unnecessarily puts additional stress on the engines and generators. These stresses include increased combustion chamber pressures, increased combustion chamber temperatures, increased exhaust temperatures, increased connecting rod forces, increased shaft torques, increased turbocharger speeds and increased generator vibrations. While the generator set is designed and proven to be capable of operating between 103 to 110%, operating at these power levels is not necessary to assure the engines can provide their required loads.

This LAR proposes Unit 2 EDG monthly testing at 4000 kW, and 24-month testing between 100 to 110% of their continuous rating for the 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months portion of the test and greater than or equal to 4000 kW for the remainder of the test. These tests will continue to demonstrate TS operability of the Unit 2 EDGs. This LAR also proposes to test the Unit 1 EDGs at or above 2500 kW for the remainder portion of the 24-month test to demonstrate TS operability.

With the TS changes proposed in this LAR the plant will continue to operate safely and the health and welfare of the public is protected.

3. TECHNICAL EVALUATION PlNGP is a two unit plant located on the right bank of the Mississippi River approximately 6 miles northwest of the city of Red Wing, Minnesota. The facility is currently owned and operated by NSPM which does business as Xcel Energy.

Originally PlNGP was licensed, owned and operated by Northern States Power Company (NSP). From August 2000 through September 2008, PlNGP was operated by Nuclear Management Company, LLC (NMC).

Each unit at PlNGP employs a two-loop pressurized water reactor designed and supplied by Westinghouse Electric Corporation. The initial PlNGP application for a Construction Permit and Operating License was submitted to the Atomic Energy Commission (AEC) in April 1967. The Final Safety Analysis Report (FSAR) was submitted for application of an Operating License in January 1971. Unit 1 began commercial operation in December 1973 and Unit 2 began commercial operation in December 1974.

The PlNGP was designed and constructed to comply with NSP's understanding of the intent of the AEC General Design Criteria (GDC) for Nuclear Power Plant Construction Permits, as proposed on July 10, 1967. PlNGP was not licensed to NUREG-0800, "Standard Review Plan (SRP)." Since EDGs D5 and D6 were added to the plant in the early 19901s,the SRP was invoked on some aspects of their design as specified in the project design report, References 1 and 2.

Page 4 of 30

Enclosure NSPM EDG Test Loads Technical Description of D5 and D6 The Unit 2 Emergency Diesel Generators consist of two tandem-drive units (gensets) manufactured by Societe Alsacienne de Constructions Mecaniques de Mulhouse (SACM), each rated at 5400 KW continuous (8750 hour0.101 days 2.431 hours 0.0145 weeks 0.00333 months basis), 0.8 power factor, 1200 rpm, 4160V, 3-phase, 60 Hertz. Each engine is a SACM UD45 V-16, four-cycle diesel engine, that is, the 5400 kW generator is driven by two V-16 engines which share the load by use of a common electronic governor system. Subsequent to NSP1spurchase of D5 and D6, Wartsila bought SACM; thus, the engine vendor in the remainder of this LAR will be referred to as Wartsila SACM.

Current TS 3.8.1, "AC Sources - Operatinq", Requirements and Basis SR 3.8.1.3 requires that every 31 days:

Verify each DG is synchronized and loaded and operates for 160 minutes at a load:

a. Unit 1; 2 2500 kW; and

b. Unit 2; 2 5100 kW and 5 5300 kW.

SR 3.8.1.9 requires that every 24 months:

Verify each DG operates for 124 hour0.00144 days 0.0344 hours 2.050265e-4 weeks 4.7182e-5 months s:

a. For 2 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months loaded:

Unit 1 2 2832 kW, and

< 3000 kW Unit 2 2 5562 kW, and

< 5940 kW; and

b. For the remaining hours of the test loaded:

Unit 1 1 2 4 7 5 kW, and Unit 2 2 4860 kW; and An LAR was submitted March 20, 1992 to incorporate the Unit 2 EDGs, D5 and D6.

The NRC approved incorporation of the Unit 2 diesels in license amendments 103 and 96, for Units 1 and 2 respectively, issued December 17, 1992 (Reference 3) which revised TS to require monthly testing at loads 2 5100 kW and 5 5300 kW and 18-month test loads at 105 to 110% of their continuous load rating. The NRC Safety Evaluation basis for this load range was:

Page 5 of 30

Enclosure NSPM EDG Test Loads Proposed changes to TS Sections 4.6.A.l .e, 4.6.A.2.c and 4.6.A.3.c will invoke new requirements for monthly, semi-annual, and 18-month surveillance testing for Unit 2 EDG to assure that the EDG have the capability to start, accelerate to synchronous speed, and accept load. They involve loading each Unit 2 EDG to between a minimum of 5100 kW and a maximum of 5300 kW. The mi nimum 5100 kW test load has been chosen to assure that either Unit 2 EDG has the capacity and the capability to assume the maximum auto-connected load for Unit

2. The maximum 5300 kW test load in TS Sections 4.6.A.l .e, 4.6.A.2.c and 4.6.A.3.c also corresponds to the load proposed for the TS surveillance Section 4.6.A.3.b.3. It is noted that, although 5100 kW is not the continuous rating of the Unit 2 EDG, it is significantly above the maximum auto-connected load. The current maximum auto-connected load is more than 1000 kW under the 5100 kW minimum test load for the Unit 2 EDG. Therefore, the proposed TS Section 4.6.A.3.b.3 requirement to verify that the auto-connected loads do not exceed 5100 kW for each Unit 2 EDG is conservative.

Specification 4.6.A.3.c is revised to add 18-month full load carrying capacity tests of each EDG for an interval of not less than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months of which 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months are at a load equal to 105 - 110 percent of the continuous rating of an EDG and 22 hours2.546296e-4 days 0.00611 hours 3.637566e-5 weeks 8.371e-6 months are at a load equal to 90 - 100 percent of the continuous rating. During this test, the voltage and frequency are to be verified to be 4160 & 420 Volts and 60 1.2 Hertz. This revision is acceptable.

(TS Sections 4.6.A.I.e and 4.6.A.3.c provided TS requirements for monthly and 18-month surveillance testing which the Improved TS (ITS) conversion license amendment translated into approximately equivalent requirements in SR 3.8.1.2, SR 3.8.1.3 and SR 3.8.1.9. TS Section 4.6.A.2.c semi-annual load testing requirements were removed from TS during ITS conversion. TS Section 4.6.A.3.b.3 requirements, for verification of the auto-connected loads every 18 months, were removed from TS prior to ITS conversion.)

The NRC Staff Safety Evaluation concluded:

The licensee's proposed TS operability and surveillance requirements for the new D5 and D6 diesel generator have been evaluated for conformance with the staff criteria of the Standard Technical Specifications (STS). They have been found to conform to this guidance with the exception noted above relating to testing at less than the rated continuous load. This exception is acceptable to the staff based on the large margin between the emergency load requirement and the test load.

Neither the NRC Staff Safety Evaluation nor the supporting LAR, dated March 20, 1992, cited specific regulatory guidance for selecting the SR test loads.

Due to concerns that the test range from 105 - 110% of the continuous rating was too Page 6 of 30

Enclosure NSPM EDG Test Loads narrow for the instrument uncertainty and could cause engine operation above 1lo%, a TS change was submitted to the NRC on October 3, 1994 to change the range to 103 -

110% rated load. The NRC approved this change by license amendments 113 and 106, for Units 1 and 2 respectively, issued January 5, 1995 (Reference 4) for the following reasons:

The highest anticipated event loads at Prairie Island are 2510 kW and 3813 kW for Unit 1 and Unit 2, respectively. For the EDGs, 103 percent of the continuous rating represents a significantly greater load on the EDGs than the highest anticipated event load for either unit.

Unit I , 103 percent of 2750 kW (continuous rating) = 2832.5 kW (represents 112.8 percent of the highest anticipated event load)

Unit 2, 103 percent of 5400 kW (continuous rating) = 5562 kW (represents 145.9 percent of the highest anticipated event load)

A test load of I 0 3 percent is significantly greater than the load required for each unit during accident conditions. Since the surveillance test would continue to demonstrate an adequate level of electrical load carrying capacity to ensure that each EDG is capable of performing its accident-mitigating function, the NRC staff finds the proposed change of the 24-hour test band from 105-110 percent to 103-110 percent, to be acceptable.

The NRC Staff SE conclusion on page 4 stated:

The staff concludes that changing the 24-hour test band for the EDGs at Prairie Island from 105-110 percent to 103-110 percent does not affect the EDG's ability to carry required loads, and thus perform their accident mitigation function, since the EDGs have significantly greater load carrying capacity than that required during a worse case accident condition.

Proposed Surveillance Requirement chanqes and benefits This LAR proposes to revise the Unit 2 EDG monthly surveillance testing requirement from the range greater than or equal to 5100 kW and less than or equal to 5300 kW to greater than or equal to 4000 kW.

The revised SR 3.8.1.3 would state:

Verify each DG is synchronized and loaded and operates for 2 60 minutes at a load:

a. Unit 1; 2500 kW; and

b. Unit 2; 2 4000 kW.

Page 7 of 30

Enclosure NSPM EDG Test Loads Associated with this proposed TS change, NSPM also commits to perform a monthly test between 5100 to 5300 kW which would not be a part of the TS required test acceptance criteria. Operating issues observed at loads above 4000 kW would be resolved within NSPM's corrective action process.

NSPM proposes that testing for TS operability at 4000 kW will adequately demonstrate that the EDGs have the capacity and the capability to assume the maximum auto-connected load. Since the licensing basis loads for the Unit 2 EDGs are well below the current TS minimum test load of 5100 kW, it is not necessary to test these EDGs at this higher load to demonstrate the diesels' capability to carry their licensing basis loads.

Through this LAR, NSPM proposes a better method for managing EDG operating events which may increase EDG availability, allow more accurate troubleshooting and facilitate more efficient maintenance implementation.

As discussed further below, the use of low sulphur diesel fuel oil (DFO) mandated in the United States has caused problems with operation of these EDGs at their continuous load rating which does not appear when the EDGs are operated at 4000 kW. Thus, NSPM concludes that these EDGs would have always supplied their required licensing basis loads for the required mission time.

When the low-sulphur fuel oil issues appeared, NMC, the plant operator at that time, declared an affected EDG inoperable and unavailable to effect repairs. Performance of these repairs on an emergent basis increases the total overall EDG out of service time.

The plant staff is challenged by the tight schedule to perform these repairs which creates an error likely environment.

Since NSPM will continue to perform monthly tests at loads comparable to the EDG's continuous rating, emergent operating issues at higher operating loads will continue to be identified and can be resolved in a timely manner. Since immediate TS inoperability would not be involved, the plant would perform repairs during a planned EDG out-of-service period. Planned outages allows for better troubleshooting and investigation; securing required parts prior to removal of the EDG from service; pre-staging of parts, tools and support structures in the work area; rescheduling of competing work; and pre-scheduling of plant human resources. Pre-planning creates an environment which is less error likely. Pre-planned repair activities are safer, better quality, more efficient, and result in less out-of-service time for the EDGs. Pre-planned repair outages are also less likely to challenge the TS allowed 14-day Completion Time.

This LAR proposes three changes to SR 3.8.1.9: increase the Unit 1 EDG remainder portion of the test from 2475 kW to 2500 kW; revise the Unit 2 EDG 2-hour portion of the testing requirement from the range greater than or equal to 5562 kW and less than or equal to 5940 kW to a new minimum test load of greater than or equal to 5400 kW; Page 8 of 30

Enclosure NSPM EDG Test Loads and revise the Unit 2 remainder of the test from 4860 kW to 4000 kW. The revised SR 3.8.1.9 would state:

Verify each DG operates for 2 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months s:

a. For 5 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months loaded:

Unit 1 2 2832 kW, and

-< 3000 kW Unit 2 2 5400 kW, and

< 5940 kW; and

b. For the remaining hours of the test loaded:

Unit 1 ,2500 kW, and Unit 2 5 4000 kW; and The Unit 1 EDG 2-hour test loads remain unchanged and the Unit 2 EDG 2-hour upper test load limit remains unchanged.

Increasing the Unit 1 EDG testing loads will make the test consistent with the monthly test and improve TS use by the operators. Reducing the Unit 2 testing loads will result in less stresses to engine components. Less stress to engine components also reduces the possibility of engine problems. For example, both the D5 and D6 diesel engines have had small piston cracks in the reentrant bowl lips. The root cause has been identified as elevated temperatures associated with operation at high loads. NMC removed these diesel engines from service to replace pistons that had indications of this type which has resulted in unavailability of the engines during piston replacements and post maintenance testing. The availability of the Unit 2 EDGs may be increased in the future if the 24-month test load on these diesel engines is reduced as proposed in this LAR.

Technical basis for changes The plant safeguards buses are normally supplied power from offsite sources. The safety function of the EDGs is to supply power to its associated unit during a design basis accident (DBA) concurrent with a loss of offsite power (LOOP). The PlNGP EDGs also provide the alternate AC source specified in 10 CFR 50.63 during an SBO in the opposite unit.

If the offsite sources should fail, backup power is provided by two EDGs in each unit sized and connected to serve the engineered safety features equipment of the unit.

Each EDG is sized to start and carry the engineered safety features load required for the design basis accident (DBA) and concurrent LOOP. For PlNGP Unit 2 the "worst Page 9 of 30

Enclosure NSPM EDG Test Loads case" DBA loads, provided in the PINGP Updated Safety Analysis Report (USAR)

Table 8.4.-2. are 3684 kW.

In addition for PINGP, in the event of an SBO condition, each EDG is capable of sequentially starting and supplying the LOOP loads for its unit as well as the essential loads of the blacked out unit. The limiting Unit 2 LOOP loads are given in USAR Table 8.4-4. The maximum predicted LOOP-SBO load on D5 or D6 is approximately 3685 kW.

Changes to SR 3.8.1.3 NSPM conservatively chose 4000 kW as the proposed Unit 2 EDGs test loading in SR 3.8.1.3 which, as discussed above, is well above the safety function load (3684 kW) and the LOOP-SBO load (3685 kW).

The plant TS include a Limiting Condition for Operation (LCO) for the EDGs under the requirements of 10CFR 50.36(c)(2)(ii) which requires an L C 0 of a nuclear reactor for an item meeting one or more of the specified criteria. The EDGs meet Criterion 3 because they are components that are part of the primary success path to mitigate a design basis accident. 10CFR 50.36 requires SRs in TS to assure that the L C 0 will be met.

LC0 3.8.1 requires two EDGs to be operable and SR 3.8.1.3 is one of the SRs which demonstrates D5 and D6 are operable. TS Section 1. I defines TS operability as:

A system, subsystem, train, component, or device shall be OPERABLE or have OPERABILITY when it is capable of performing its specified safety function(s) and when all necessary attendant instrumentation, controls, normal or emergency electrical power, cooling and seal water, lubrication, and other auxiliary equipment that are required for the system, subsystem, train, component, or device to perform its specified safety function(s) are also capable of performing their related support function(s).

The proposed 4000 kW test loading is well above the safety function loads on D5 and D6 and the necessary EDG attendant instrumentation, controls, cooling, lubrication and other auxiliary equipment required for the EDGs to perform their safety function loads are also tested at this loading. Thus, testing D5 and D6 at or above 4000 kW will demonstrate that the EDGs are operable within the TS definition of operability. The current test loading of 5100 kW is unnecessarily conservative in that a lower test load will adequately demonstrate EDG operability.

The proposed 4000 kW test loading meets the acceptance criteria that the NRC established when the current PINGP TS SR test loading was approved. The NRC stated in Reference 3 that:

. . . although 5100 kW is not the continuous rating of the Unit 2 EDG, it is significantly above the maximum auto-connected load. The current maximum Page 10 of 30

Enclosure NSPM EDG Test Loads auto-connected load is more than 1000 kW under the 5100 kW minimum test load for the Unit 2 EDG.

NSP analyses demonstrate that the current maximum auto-connected loads are less than the proposed 4000 kW minimum TS test loading for the Unit 2 EDGs.

It is NSPM's understanding that there is only one other nuclear power plant in the United States that uses the SACM UD45 tandem diesel generators (DGs), the Calvert Cliffs Nuclear Power Plant (CCNPP). CCNPP installed two SACM UD45 DGs rated at 5400 kW of which one is an EDG and the other is the SBO alternate AC source for both units required by 10 CFR 50.63.

The SACM diesel generators were incorporated into the CCNPP licensing basis through an LAR dated November 1, 1995 (Reference 5) and the NRC Safety Evaluation dated April 2, 1996 (Reference 6). In Reference 5, CCNPP management proposed monthly testing of the SACM EDG at the loading of 4000 kW based on approximately 3400 kW of plant safety related loads and 566 kW necessary to support operation of the SACM EDG. The 4000 kW test loading proposed in this LAR also meets the acceptance criteria that the NRC Staff applied to the CCNPP SACM EDG surveillance test loading. In Reference 6 the NRC Staff stated, The licensee stated that the proposed minimum test loading of 4000 kW for EDG 1A is based on a maximum accident loading analysis. The licensee further stated that since the surveillance requirements are intended to demonstrate the operability of the EDGs by ensuring that they can provide a reliable source of power to mitigate the consequences of an accident and shut down the unit after an accident, the acceptance criterion for the monthly surveillance for EDG 1A will be 4000 kW.

The staff agrees with the licensee that the proposed TSs will, as detailed above, adequately demonstrate the EDG's ability to perform their [safety related] SR function which is to provide a reliable source of electrical power to the [safety related] SR busses that is necessary to power accident mitigation equipment if offsite power is unavailable.

The proposed minimum test loading of 4000 kW for PlNGP Unit 2 EDGs is above the maximum accident loading and thus, this proposed test loading will adequately demonstrate the EDGs' ability to perform their safety function.

NSPM will continue to operate D5 and D6 at or above 90% rated loading on a schedule consistent with the performance of SR 3.8.1.3 to monitor engine health at, or near, their continuous rating load. Operation at or above 90% rated power is adequate to identify engine degradation that could jeopardize the ability of the EDG capacity and the capability to assume their auto-connected safety function loads and assume the LOOP-SBO loads. Any degradation in the EDGs' performance between the continuous rating Page 11 of 30

Enclosure NSPM EDG Test Loads (5400 kW) and the capacity needed to perform the safety function (4000 kW) will be evaluated under NSPM1scorrective action program, which includes trending capabilities, and corrected under the maintenance program.

For example, crankcase pressure will continue to be one of the parameters which will be monitored. Wartsila SACM has provided guidance for normal and abnormal crankcase pressures which is included in PlNGP procedures. Following engine overhaul the crankcase pressure is expected to range from 5 to 20 mm H20. Operation with the crankcase pressure in the range from 20 to 40 mm H 2 0 is acceptable in accordance with Wartsila SACM guidance. However, per PlNGP procedures, in this range an Action Request would be written and an evaluation would be performed under the plant's corrective action program.

PlNGP Unit 2 has shut down three times due to emergent EDG issues to perform repairs which could not be completed within the TS 7-day Completion Time at that time.

The Unit 2 Wartsila SACM EDGs were installed at PlNGP in 1992 and were operated successfully from that time until 2001. In 2001, Unit 2 was shut down to rebuild D6; the type of engine lubricating oil was also changed at that time. In 2005, Unit 2 was shut down for rebuilding D5. In 2006, Unit 2 was again shutdown to rebuild D6 and modifications were performed to reduce the lubricating oil level.

Although many repairs have been performed on these Unit 2 EDGs since 2001, the causes are now known. Through extensive investigations, the determination has been made that all of the major problems are a result of reduction of sulphur content in the diesel fuel oil in combination with the EDG design and operating conditions.

The cause of the elevated crankcase pressure, when operating at loads approaching the continuous rating, is that the engine design is not compatible with current fuel oil sulphur content and the manufacturer's specified lubricating oil, that is, the lubricating oil total base number (TBN) and ash content combination.

The crankcase breather design exacerbates the formation of lubrication oil derived deposits by routing crankcase gases back into the combustion process. The breather system also appears to be unable to manage increases in blow-by flow and the cylinder liner and piston design appears to be unable to manage the deposits that form.

As cylinder deposits form and accumulate, cylinder blow-by flow increases due to poor sealing of the piston rings which in turn requires the crankcase breather system to evacuate a larger volume of crankcase gases to maintain a steady crankcase pressure.

As a greater volume of crankcase gases is evacuated, more carry-over of lubrication oil back to the combustion chamber occurs. This then promotes the formation of more deposits and this cycle continues until engine crankcase pressure exceeds acceptable limits.

The crankcase pressure was acceptable at 4,000 kW which is above the accident loads expected during the bounding events. However, the required Technical Specifications Page 12 of 30

Enclosure NSPM EDG Test Loads testing is performed at 5,200 kW. While the engine would have been able to perform under accident conditions, the engine was not able to complete the required surveillance testing. Consequently, emergent preventative maintenance has occurred due to this issue.

Contributing factors include:

Federal Government mandated reduction in diesel fuel oil sulphur concentrations.

Use of Shell Rotella T 15W-40 lubricating oil that has higher TBN and ash content than current fuel oil sulphur concentrations support. Additionally, multi-viscosity oils are more volatile than straight weight oils which contributes to lubricating oil carryover to the combustion chamber via the crankcase breather system.

Piston design may be contributing to deposit formation and management.

Formation of deposits in the piston ring grooves inhibit the ability of the piston rings to float. This causes premature cylinder liner and piston ring wear which contributes to additional combustion gases entering the crankcase.

Operating load during testing is much higher than accident loads. Crankcase pressure returns to normal when loads are reduced to approximately 4000 kW (which bounds the maximum accident and design basis loads).

The engines were designed and tested using higher sulphur fuel oil.

The sulphur content of the DFO supplied to the plant was reduced in the early 2000's in response to the Federal Government mandate to lower DFO sulphur levels. The engine problems due to low sulphur fuel oil have only occurred at power levels above 5100 kW. These problems occur above 5100 kW, and not at lower loads, for the following reasons:

More fuel is being delivered to each cylinder which results in higher cylinder pressure from the combustion event and more combustion gases being forced past the piston rings into the crankcase. The crankcase has a finite volume, thus the extra gases cause a greater crankcase pressure. The breather system does not appear to have the ability to evacuate increased volumes of crankcase gases. When load is reduced, cylinder pressure is reduced and the cylinders seal better allowing less combustion gases to enter the crankcase. The lesser amount of crankcase gases can then be managed (removed from the crankcase) to maintain a normal crankcase pressure.

Cylinder temperatures are higher (again from more fuel being delivered) which results in higher piston crown temperatures. Higher piston temperatures cause the first ring groove (top piston compression ring) to "pinch" together resulting in sticking piston rings. Sticking piston rings result in poor cylinder sealing which allows more combustion gases to enter the crankcase. Again, the crankcase has a finite volume and the extra gases cause a greater crankcase pressure. The breather system does not appear Page 13 of 30

Enclosure NSPM EDG Test Loads to have the ability to evacuate increased volumes of crankcase gases.

When load is reduced, cylinder and piston crown temperature is reduced allowing the piston ring groove to return to a greater clearance, freeing up a sticking ring, forming a better cylinder seal, and allowing less combustion gases to enter the crankcase. The lesser amount of crankcase gases can then be managed, that is, removed from the crankcase, to maintain normal crankcase pressure. Piston ring sticking is exacerbated by deposits that form in the ring grooves from the lubricating oil and fuel oil interaction.

At lower loads (4000 kW), piston temperatures and cylinder pressures are lower. This allows for better cylinder sealing and less combustion gases entering the crankcase. Then, at this load, the crankcase breather system can manage the gases that enter the crankcase, keeping crankcase pressure at normal value.

These engines would likely have supplied their required loads for their mission time at any of the times when these EDGs were declared inoperable and repairs initiated.

Based on the results of the investigations, TS testing of these EDGs at 4000 kW will adequately demonstrate the capability of the EDG to perform their design functions.

PlNGP Unit 2 shut down three times due to emergent EDG issues which challenged the plant resources and may have created error likely situations. Continuing to remove these engines from service for emergent repairs increases plant vulnerability instead of decreasing vulnerability when operation at a load value in excess of accident loads (greater than or equal to 4000 kW) can be performed acceptably.

Through TS testing at a lower load and operability testing at loads comparable to their continuous rating, NSPM proposes a better method for managing EDG operating events which will increase EDG availability, allow more accurate troubleshooting and facilitate more efficient maintenance implementation.

The proposed TS operability testing at or above 4000 kW will allow resolution of EDG issues through the corrective action program and maintenance program in a deliberate, planned fashion instead of removing the engines from service for each emergent EDG operating event.

NSPM commits to continue testing the Unit 2 EDGs at, or near, full load for trending purposes. The corrective action process will be used to evaluate abnormal trends identified during operation above the SR required test loading and schedule repairs without unnecessary forced EDG and plant outages.

Continued monthly testing at near full load (>go% rated loading) will continue to identify abnormal trends in engine health which can be addressed using the corrective action program and the normal work control process. Due to February 2006 modifications of the sump oil level alarms, future monitoring of high crankcase pressure should more Page 14 of 30

Enclosure NSPM EDG Test Loads accurately provide indications of true engine health concerns, such as, piston ring and liner degradation causing blow-by.

NSPM also anticipates that the Unit 2 plant availability may be increased by avoiding plant shutdown associated with D5 or D6 corrective maintenance for emergent EDG operating issues. With the TS changes proposed in this LAR, Unit 2 EDG issues identified during operation above the required SR loading may be trended and scheduled for resolution during planned EDG maintenance outages or during plant refueling outages if necessary.

The Unit 2 EDGs are not committed to any regulatory guidance for testing and thus the proposed monthly test at 4000 kW does not deviate from any standard applicable to these EDGs. A design report, Reference 1, for the addition of EDGs D5 and D6 was supplied to the NRC by letter dated November 27, 1990 and supplemented December 23, 1991, Reference 2. The design report cited applicable regulatory guidance and standards which were the basis for D5 and D6 design criteria and acceptance testing.

The cover letter for the design report explicitly stated:

An important function of this report is to detail our commitments to various codes, standards, and Regulatory Guides. Our commitments, and exceptions, to the various "Standards" are explicitly described in the various sections of the report. Note, however, that these commitments are for design, procurement, fabrication and construction only: operational and surveillance commitments will be made through the License Amendment Request.

The design report did invoke Regulatory Guide (RG) 1.9, "Selection, Design and Qualification of Diesel Generator Units Used As Standby (On-site) Electric Power Systems at Nuclear Power Plants", Revision 2, December 1979, and RG 1.108, "Periodic Testing of Diesel Units Used As On-site Electric Power Systems at Nuclear Power Plants", Revision 1, August 1977; however, they were applied for design purposes and not committed to for operation or surveillance testing. The LAR which incorporated D5 and D6, Reference 7, submitted March 20, 1992, did not reference any regulatory guidance as the basis for the proposed EDG surveillance requirements.

Likewise, license amendments 103 and 96, Reference 3, which approved use of D5 and D6 did not cite any regulatory guidance as the basis the EDG surveillance test requirements.

The proposed TS monthly test load of 4000 kW does not involve a re-rate or de-rate of these diesel generator sets. Ratings are used by manufacturers to properly size diesel generators so that they will not be overloaded and damaged in their intended application. The "continuous" rating of a diesel generator is generally the output available without varying the load for an unlimited time. Diesel generator manufacturers may recommend periodic test loads to confirm the capability of the units, but these tests are not a requirement to maintain the diesel generator rating. Although NSPM commits to perform monthly testing at loads comparable to their continuous rating, performance at only the proposed TS load of 4000 kW would not violate any testing Page 15 of 30

Enclosure NSPM EDG Test Loads recommendations of Wartsila SACM, the diesel generator manufacturer. Thus, re-rating D5 and D6 for this LAR was not a consideration.

NSPM is committed to maintain these EDGs to have the necessary reliability and availability to perform their post-accident and SBO functions. Since the EDG operating problems were identified in 2001, modifications have been made to improve their operations with low sulphur DFO, including: the lubrication oil type was changed in 2001 to be more compatible with low sulphur DFO; the crankcase manometer was modified in 2006 to improve monitoring of the crankcase pressure; and since early 2008, a sulphur based additive has been added to the Unit 2 DFO supply. NSPM continues to explore means to improve or optimize the Unit 2 EDG performance while complying with vendor recommendations.

Changes to SR 3.8.1.9 The 3684 kW DBA load and 3685 kW SBO load are the current highest anticipated loads on the Unit 2 EDGs which supersede those cited by the NRC in their January 5, 1995 Safety Evaluation (Reference 4).

This LAR does not propose test load reductions to the required Unit 1 EDG test loads because: 1) D l and D2 do not have as much margin between the test load and the post-accident and station blackout loads; and 2) D l and D2 have not shown evidence of unusual wear similar to D5 and D6 which has caused unscheduled or additional maintenance. This LAR does propose to increase the Unit 1 EDG lower test load for the remainder of the test from 2475 kW to 2500 kW to be consistent with the monthly test load. This slight increase in test load will continue to assure that the Unit 1 EDGs are operable and capable of supplying their design loads and will improve operator usage of the TS.

The plant TS include an LC0 for the EDGs under the requirements of 10CFR 50.36(c)(2)(ii) which requires an L C 0 of a nuclear reactor for an item meeting one or more of the specified criteria. The EDGs meet Criterion 3 because they are components that are part of the primary success path to mitigate a design basis accident. 10CFR 50.36 requires SRs in TS to assure that the LC0 will be met. LC0 3.8.1 requires two EDGs to be operable and SR 3.8.1.9 is one of the SRs which demonstrates D5 and D6 are operable. TS Section 1. I defines TS operability as:

A system, subsystem, train, component, or device shall be OPERABLE or have OPERABILITY when it is capable of performing its specified safety function(s) and when all necessary attendant instrumentation, controls, normal or emergency electrical power, cooling and seal water, lubrication, and other auxiliary equipment that are required for the system, subsystem, train, component, or device to perform its specified safety function(s) are also capable of performing their related support function(s).

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Enclosure NSPM EDG Test Loads The proposed 5400 kW 2-hour test loading is well above the safety function loads on D5 and D6 and the necessary EDG attendant instrumentation, controls, cooling, lubrication and other auxiliary equipment required for the EDGs to perform their safety function loads are also tested at this loading. Thus, testing D5 and D6 for 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months at or above 5400 kW will demonstrate that the EDGs are operable within the TS definition of operability. The current test loading of greater than or equal to 5562 kW is unnecessary in that a lower test load will adequately demonstrate EDG operability.

The proposed minimum 5400 kW test loading meets acceptance criteria that the NRC established when the current PlNGP TS SR test loading was approved. The NRC stated in Reference 4 that:

A test load of 103 percent is significantly greater than the load required for each unit during accident conditions. Since the surveillance test would continue to demonstrate an adequate level of electrical load carrying capacity to ensure that each EDG is capable of performing its accident-mitigating function, the NRC staff finds the proposed change of the 24-hour test band from 105-110 percent to 103-110 percent, to be acceptable.

The test power of greater than or equal to 5400 kW significantly exceeds the LOOP-LOCA loads (3684 kW) encountered by D5 or D6 under postulated accident conditions.

This is sufficient margin to show the diesel can support the electrical needs during these events. The proposed continuous run load of greater than or equal to 4000 kW for the remainder of the test also exceeds the LOOP-LOCA loads of 3684 kW and again this adequately demonstrates the engines' capability to handle these events.

Thus, with the changes proposed in this LAR, the test loads continue to be greater than the required post event Unit 2 diesel loading and will continue to demonstrate an adequate level of electrical load carrying capacity to ensure that each EDG is capable of performing its accident-mitigating function.

Lowering the test loads on the D5 and D6 diesels will not impact accident load capability of the engines, but it will reduce unnecessary stress on engine components.

For example, as discussed above, the higher power output of the engine results in increased stress in the piston reentrant bowl lips. As power level goes up this area sees higher temperature and stress.

NMC, the plant operator at the time, had previously observed lip cracking during preventive maintenance outages and elected to replace these pistons which resulted in additional time for repair. These repairs increased the accrued engine out of service time. Lowering the unnecessarily conservative 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months power test minimum test load of 103% of rated loading to a lower level and reducing the test load during the remainder of the 24-hour test will also lower the stress on the piston lip thus reducing the likelihood of cracking. NSPM anticipates that reducing the amount of cracking observed in the piston lip area will improve engine reliability from reduced maintenance and less out of service time will be accrued on the engine as a result.

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Enclosure NSPM EDG Test Loads Testing for the remainder of the 24-hour test at the proposed reduced test load will continue to demonstrate the operability of the Unit 2 EDGs for the reasons discussed in the SR 3.8.1.3 Section above. This change should also improve EDG availability due to reduced wear and challenges to engine performance. As discuss below, this change is also consistent with the TS requirements for the CCNPP SACM EDG.

Conclusions This LAR proposes to revise SR 3.8.1.3 testing loading for the Unit 2 EDGs to greater than or equal to 4000 kW. This proposed test loading will assure that both Unit 2 EDGs have the capacity and the capability to assume the maximum auto-connected load for Unit 2. This test loading also demonstrates that both Unit 2 EDGs have the capacity and the capability to assume the LOOP-SBO loadings. These TS changes are expected to increase the Unit 2 EDG availability by allowing plant management to focus corrective maintenance activities on EDG issues which truly challenge EDG operability.

These changes may also increase the Unit 2 plant availability. NSPM will continue to operate the Unit 2 EDGs at or near their rated loading to monitor for engine degradation. Issues identified will be trended in the plant corrective action program and corrected under the maintenance program.

The proposed 4000 kW test load meets an original NRC acceptance criteria for the current TS test loads in that it is above the maximum auto-connected loads. The Unit 2 EDGs have experienced operating events since 2001 which has resulted in three Unit 2 shut downs; however, during each of these the EDGs were capable of supplying their design basis loads and SBO loads for their mission time. The source of the problem is now known to be low sulphur DFO; NMC implemented remedies and NSPM is continuing to pursue further remedies. Since the proposed TS testing meets the manufacturer's testing recommendations, this proposed change does not involve re-rating the EDGs. With the commitment to continue monthly testing at or above 5100 kW, the intent of RG 1.9 will continue to be met.

This LAR proposes to revise the remainder portion of the SR 3.8.1.9 test loading for the Unit 1 EDGs to 2500 kW which is consistent with the monthly test loading, assures the EDGs are operable and capable of supplying their design loads, and will improve TS usage.

This LAR proposes to revise the 2-hour portion of SR 3.8.1.9 test loading for the Unit 2 EDGs to greater than or equal to 5400 kW and less than or equal to 5940 kW and revise the remainder of the test to be performed at or above 4000 kW. These proposed test loadings will assure that both Unit 2 EDGs have the capacity and the capability to assume the maximum auto-connected load for Unit 2. These test loadings also demonstrate that both Unit 2 EDGs have the capacity and the capability to assume the LOOP-SBO loadings.

Page 18 of 30

Enclosure NSPM EDG Test Loads Operation and maintenance of the Prairie Island Nuclear Generating Plant with the Technical Specification revisions proposed in this license amendment request will demonstrate the emergency diesel generators are operable, can perform their required safety and station blackout functions and continue to protect the health and safety of the public.

4. REGULATORY SAFETY ANALYSIS 4.1 Applicable Regulatory RequirementsICriteria Title 10 Code of Federal Regulations 50.36. "Technical specifications":

(c) Technical specifications will include items in the following categories:

(3) Sun/eillance requirements. Surveillance requirements are requirements relating to test, calibration, or inspection to assure that the necessary quality of systems and components is maintained, that facility operation will be within safety limits, and that the limiting conditions for operation will be met.

This license amendment request proposes changes to surveillance requirements (SR) 3.8.1.3 and SR 3.8.1.9 relating to testing to assure that the necessary quality of the Unit 1 and 2 emergency diesel generators is maintained and that the limiting conditions for operation will be met. The Technical Specification limiting conditions for operation requires two emergency diesel generators to be operable for each unit. SRs 3.8.1.3 and 3.8.1.9 fulfill the requirements of this regulation by demonstrating that the emergency diesel generators meet the Prairie Island Nuclear Generating Plant Technical Specification definition for operability which states:

A system, subsystem, train, component, or device shall be OPERABLE or have OPERABILITY when it is capable of performing its specified safety function(s) and when all necessary attendant instrumentation, controls, normal or emergency electrical power, cooling and seal water, lubrication, and other auxiliary equipment that are required for the system, subsystem, train, component, or device to perform its specified safety function(s) are also capable of performing their related support function(s).

This license amendment request proposes to revise SR 3.8.1.3 to require monthly testing of the Unit 2 emergency diesel generators at 4000 kW. This test loading is well above the safety function loads that the Unit 2 emergency diesel generators are required to supply. The Unit 1 emergency diesel generator test load for the remainder of the SR 3.8.1.9 test (the balance of the test after the 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months portion) is proposed to be increased to 2500 kW which is consistent with the monthly test load and will demonstrate that the operability.

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Enclosure NSPM EDG Test Loads This license amendment request also proposes to revise SR 3.8.1.9 to require testing the Unit 2 emergency diesel generators at a load greater than or equal to 5400 kW and less than or equal to 5940 kW for the 2-hour portion of the test and greater than or equal to 4000 kW for the remainder of the test. These test loadings are above the safety function loads that the Unit 2 emergency diesel generators are required to supply. Furthermore, at these proposed test loadings the necessary emergency diesel generator attendant instrumentation, controls, cooling, lubrication and other auxiliary equipment required for the emergency diesel generators to perform their safety function loads are also tested. Thus, testing the Unit 2 emergency diesel generators at the loadings proposed in this license amendment request will demonstrate that the emergency diesel generators are operable within the Technical Specification definition of operability.

Thus with the changes proposed in this license amendment request, the requirements of Title 10 Code of Federal Regulations 50.36 continue to be met and the plant Technical Specifications will continue to provide the basis for safe plant operation.

Title 10 Code of Federal Requlations 50.63, "Loss of all alternating current power":

2 ) Alternate AC source: The alternate AC power source(s), as defined in Section 50.2, will constitute acceptable capability to withstand station blackout provided an analysis is performed which demonstrates that the plant has this capability from onset of the station blackout until the alternate AC source(s) and required shutdown equipment are started and lined up to operate.

The Prairie Island Nuclear Generating Plant Unit 1 emergency diesel generators are the alternate AC power source for a Unit 2 station blackout event. A station blackout exists when there is a loss of offsite power and concurrent loss of both of a unit's emergency diesel generator sources. The station blackout analyses assume a loss of offsite power on one unit and a station blackout on the other unit. A station blackout is assumed to occur on only one unit of a two unit site in accordance with Regulatory Guide 1.155, "Station Blackout", August 1988. This license amendment request proposes to increase the Unit 1 emergency diesel generator SR 3.8.1.9 test load for the remainder of the test (after the 2-hour portion) to 2500 kW. Since this is an increase in the test load, testing with the proposed changes will continue to demonstrate that the Unit 1 emergency diesel generators are operable and have the capability to perform their station blackout function.

The Prairie Island Nuclear Generating Plant Unit 2 emergency diesel generators are the alternate AC power source for a Unit 1 station blackout event. After either Unit 2 emergency diesel generator has completed load sequencing and has provided power to the designated safeguards equipment (identified in Reference 8, Table 8.4-4), the plant operators will manually close two series bus-tie breakers. Thus, the Unit 2 emergency diesel generators must have the capacity and capability to supply their required Unit 2 loss of offsite power coincident with Unit 1 station blackout loads.

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Enclosure NSPM EDG Test Loads As stated in Reference 8, the maximum predicted load on either Unit 2 emergency diesel generator during a Unit 2 loss of offsite power coincident with Unit 1 station blackout is approximately 3685 kW. The SR 3.8.1.3 test loading proposed in this license amendment request (4000 kW), the SR 3.8.1.9 minimum 2-hour proposed test load (5400 kW), and the SR 3.8.1.9 test load (4000 kW) proposed for the remainder of the test (the balance of the test after the 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months portion) are all well above the Unit 2 loss of offsite power loads coincident with Unit 1 station blackout loads. Therefore, SR 3.8.1.3 and SR 3.8.1.9 will continue to demonstrate that the Unit 2 emergency diesel generators have the capacity and capability to assume their required Unit 2 loss of offsite power and Unit 1 station blackout loads.

Thus with the changes proposed in this license amendment request, the requirements of Title 10 Code of Federal Regulations 50.63 continue to be met and the plant Technical Specifications will continue to provide the basis for safe plant operation.

General Desiqn Criteria The construction of the Prairie Island Nuclear Generating Plant was significantly complete prior to issuance of 10 CFR 50, Appendix A, General Design Criteria. The Prairie Island Nuclear Generating Plant was designed and constructed to comply with the Atomic Energy Commission General Design Criteria as proposed on July 10, 1967 (AEC GDC) as described in the plant Updated Safety Analysis Report. AEC GDC proposed Criterion 39 provides guidance applicable to the design of the AC electrical power system supplies to the engineered safety features.

AEC GDC Criterion 39 - Emergency Power For Engineered Safety Features Alternate power systems shall be provided and designed with adequate independency, redundancy, capacity, and testability to permit the functioning required of the engineered safety features. As a minimum, the onsite power system and the offsite power system shall each, independently, provide this capacity assuming a failure of a single active component in each power system.

This license amendment request proposes, for the Unit 1 emergency diesel generators, to increase the remainder (the balance of the test after the 2-hour portion) of the 24 month test to be greater than or equal to 2500 kW. With this change, the Unit 1 independent alternate power systems continue to be provided with adequate capacity and testability to supply the required engineered safety features and protections.

This license amendment request proposes, for the Unit 2 emergency diesel generators, to reduce the required monthly test loading to 4000 kW, to require the minimum test loading in the 2-hour portion of the 24 month test to be greater than or equal to 5400 kW and require the remainder of the 24 month test to be performed greater than of equal to 4000 kW. The proposed test loadings will continue to assure that both Unit 2 emergency diesel generators have the Page 21 of 30

Enclosure NSPM EDG Test Loads capacity and the capability to assume the maximum auto-connected loads for Unit 2. With these changes, the Unit 2 independent alternate power systems continue to be provided with adequate capacity and testability to supply the required engineered safety features and protections.

The changes proposed in this license amendment request do not change the Prairie Island Nuclear Generating Plant's means for addressing AEC GDC Criterion 39 and the plant Technical Specifications will continue to provide the basis for safe plant operation.

Regulatow Guide 1.9, Revision 4, "Application and Testing of Safetv-Related Diesel Generators In Nuclear Power Plants", March 2007 (RG 1.9)

RG 1.9 provides surveillance testing guidance for emergency diesel generators. The Prairie Island Nuclear Generating Plant emergency diesel generators are not committed to this Regulatory Guide, or any other Regulatory Guide, for surveillance testing requirements. However, Northern States Power Company, a Minnesota corporation, (NSPM) has committed to perform monthly testing of the Unit 2 emergency diesel generators at or above 90% of their continuous rating. This testing is consistent with the intent of RG 1.9 monthly testing requirements.

NSPM submits that the testing proposed in this license amendment request will demonstrate the Unit 2 emergency diesel generators have the necessary reliability and availability to supply the loads for station blackout and design basis accidents.

NUREG-1431 Standard Technical Specifications, Westinghouse Plants, Revision 3.0, Surveillance Requirement 3.8.1.3 NUREG-1431, "Standard Technical Specifications, Westinghouse Plants," Revision 3.0 (NUREG-1431) provides format and content guidance for Technical Specifications for plants with Westinghouse Nuclear Steam Supply Systems and has been approved for use by the Nuclear Regulatory Commission. The proposed Technical Specification change for the monthly load test is consistent with the guidance of NUREG-1431 as follows.

NUREG-1431 Specification 3.8.1, Surveillance Requirement 3.8.1.3 states, "Verify each DG is synchronized and loaded and operates for 2 60 minutes at a load 2 [4500] kW and 5 [5000] kW." The NUREG-1431 Bases for Specification 3.8.1 states in the Background Section, "Ratings for Train A and Train B DGs [diesel generators] satisfy the requirements of Regulatory Guide 1.9 (Ref. 3). The continuous service rating of each DG is [7000] kW with [ I 01% overload permissible for up to 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months in any 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months period." NUREG-I431 Bases for SR 3.8.1.3 provides the basis for the specified test loads as follows:

This Surveillance verifies that the DGs are capable of synchronizing with the offsite electrical system and accepting loads greater than or equal to the Page 22 of 30

Enclosure NSPM EDG Test Loads equivalent of the maximum expected accident loads. A minimum run time of 60 minutes is required to stabilize engine temperatures, while minimizing the time that the DG is connected to the offsite source.

Because NUREG-1431 provides format and content guidance for many plants, information or values are provided for a typical plant in brackets, that is, the brackets indicate plant specific information is to be provided. For this reason, the example test loadings specified in SR 3.8.1.3 and the example continuous rating in the Bases Background are bracketed. Note, the continuous rating for the hypothetical NUREG-1431 plant is 7000 kW and the monthly test loading is between 4500 kW and 5000 kW.

The test loading proposed in this license amendment request, compared to the diesel rating, is consistent with the guidance of NUREG-1431. The Prairie Island Nuclear Generating Plant Unit 2 emergency diesel generatorsJcontinuous ratings are 5400 kW and the proposed test loading is 4000 kW.

The NUREG-1431 basis for the monthly test loading is that it verifies the capability to accept "loads greater than or equivalent to the maximum expected accident loads".

The surveillance test loading in this license amendment is also consistent with this guidance in that 4000 kW greater than the maximum expected accident loads.

4.2 Precedent SACM diesel generators are used in many applications throughout the world including many at nuclear power plants in France. It is NSPMJsunderstanding that there is only one other nuclear power plant in the United States that uses the SACM UD45 tandem diesel generators (DGs), the Calvert Cliffs Nuclear Power Plant (CCNPP). CCNPP installed two SACM UD45 DGs rated at 5400 kW of which one is an EDG and the other is the SBO alternate AC source for both units required by 10 CFR 50.63.

The SACM diesel generators were incorporated into the CCNPP licensing basis through an LAR dated November 1, 1995 (Reference 5) and the NRC Safety Evaluation dated April 2, 1996 (Reference 6). In Reference 5 CCNPP management proposed monthly testing of the SACM EDG at the loading of 4000 kW based on approximately 3400 kW of plant safety related loads and 566 kW necessary to support operation of the SACM EDG. Note two items: I ) CCNPP management committed to perform monthly testing at 90 -100% of the SACM EDG continuous rating: NSPM has made the same commitment in this license amendment request; and 2) CCNPP also increased the test loads on their existing EDGs in the Reference 5 license amendment request:

NMC, the previous PlNGP operator, increased the monthly test load for the Unit 1 EDGs in other license amendment requests (References 9 and 10) and NSPM proposes to increase the 24-month test load in this license amendment request. The Reference 5 LAR provided the following support for the 4000 kW monthly test loading:

Number 1A [SACM] EDG, with a continuous rating of 5400 kW, is capable of providing considerably more power than the 4000 kW proposed minimum test loading. As the Surveillance Requirements are intended to demonstrate the Page 23 of 30

Enclosure NSPM EDG Test Loads operability of the EDGs by ensuring that they are capable of providing a reliable source of power to mitigate the consequences of an accident, and shut down the unit following an accident, the acceptance criteria for the monthly surveillance for No. l A [SACM] EDG will be 4000 kW. However, testing will normally be performed between 90 and 100 percent of the EDG's continuous rating, but the EDG will not necessarily be considered inoperable per the Technical Specifications unless it fails to maintain 4000 kW, which would indicate that the EDG would not be capable of performing its safety function. Any degradation in the EDG's performance between the continuous rating (5400 kW) and the capacity needed to perform the safety function (4000 kW) will be evaluated under BGE's [Baltimore Gas and Electric Company] [CCNPP owner and operator in 19951 corrective action program, and corrected under the maintenance program, which incorporates trending capabilities.

The NRC stated in Reference 6, page 3 of the Safety Evaluation:

The continuous rating of [SACM] EDG 1A is 5400 kW. The licensee stated that the proposed minimum test loading of 4000 kW for [SACM] EDG 1A is based on a maximum accident loading analysis. The licensee further stated that since the surveillance requirements are intended to demonstrate the operability of the EDGs by ensuring that they can provide a reliable source of power to mitigate the consequences of an accident and shut down the unit after an accident, the acceptance criterion for the monthly surveillance for [SACM] EDG 1A will be 4000 kW. However, the testing will normally be performed at between 90 percent and 100 percent of the EDG's continuous rating. The EDG will not be considered inoperable per TSs unless it fails to maintain a 4000 kW load, indicating that it may not be capable of performing its safety function. Any degradation in the EDG's performance between the continuous rating (5400 KW) and the capacity needed to perform the safety function (4000 kW) will be evaluated under the corrective action program and corrected under the maintenance program, which incorporated trending capabilities.

The NRC concluded in Reference 6, page 14 of the Safety Evaluation:

The staff agrees with the licensee that the proposed TSs will, as detailed above, adequately demonstrate the EDG's ability to perform their SR [safety related]

function which is to provide a reliable source of electrical power to the SR busses that is necessary to power accident mitigation equipment if offsite power is unavailable. The staff has further determined that the proposed TSs are an improvement over the existing TSs, reflect the reconfiguration of the electrical system and account for the design differences in the EDGs. Therefore, we find the proposed changes to the TSs acceptable.

For the refueling cycle load testing of the SACM EDG, CCNPP management, in Reference 5, also proposed testing at the loading of 4000 kW based on approximately Page 24 of 30

Enclosure NSPM EDG Test Loads 3400 kW of plant safety related loads and 566 kW necessary to support operation of the SACM EDG. The LAR provided the following support for this test loading:

Surveillance 4.8.1.1.2.d.4 requires that each EDG be operated at least once per refueling interval at greater than or equal to 2500 kW for at least 60 minutes. For the refueling interval surveillance, using an acceptance criteria which is greater than the accident loads for that EDG provides a better indication of the ability of that EDG to support post-accident loads when required. Baltimore Gas and Electric Company proposes adopting an acceptance criteria of 4000 kW for the refueling interval Surveillance Requirement for No. 1A [SACM] EDG. This value is greater than the calculated accident loads (including No. 1A [SACM] EDG house loads) and will demonstrate the ability of No. 1A [SACM] EDG to perform its safety function.

The NRC stated in Reference 6, page 6 of the Safety Evaluation (SE):

The licensee stated increasing the acceptance criterion for the EDGs to exceed accident loads gives a better indication of the EDG's ability to support post accident loads when required.

The staff has determined that this proposed change is an improvement over the existing requirements and reflects the reconfiguration of the electrical distribution system accounting for the design differences of the EDGs. Therefore, we find the proposed changes acceptable.

The NRC concluded in Reference 6, page 14 of the SE:

The staff agrees with the licensee that the proposed TSs will, as detailed above, adequately demonstrate the EDG's ability to perform their SR [safety related]

function which is to provide a reliable source of electrical power to the SR busses that is necessary to power accident mitigation equipment if offsite power is unavailable. The staff has further determined that the proposed TSs are an improvement over the existing TSs, reflect the reconfiguration of the electrical system and account for the design differences in the EDGs. Therefore, we find the proposed changes to the TSs acceptable.

However, the staff notes that the existing Calvert Cliffs TSs and some of the proposed changes are not entirely consistent with the improved [Standard Technical Specifications] STSs. On March 31, 1995, the licensee committed to convert the Calvert Cliffs TSs to the improved TS consistent with NUREG-1432, "Standard Technical Specifications - Combustion Engineering Plants." Any inconsistencies will be addressed at that time.

Subsequently the CCNPP TS were converted to the improved TS and incorporated the requirements of Surveillance 4.8.1 . I .2.d.4 into SR 3.8.1 .I 1 which requires testing their Page 25 of 30

Enclosure NSPM EDG Test Loads SACM DG 1A for greater than or equal to 60 minutes while loaded at greater than or equal to 4000 kW within the interval of 24 months.

The proposed Prairie lsland Nuclear Generating Plant Unit 2 EDGs monthly test loading of 4000 kW is above the maximum accident loading, the 24 month test 2-hour loading of 5400 kW is above the maximum accident loading, and the 24 month test remainder (after the 2-hour test) loading of 4000 kW is above the maximum accident loading and thus, these proposed test loadings will adequately demonstrate the EDGs' ability to perform their safety function. Based on the licensing precedent cited above, the NRC Staff should find the Prairie lsland Nuclear Generating Plant proposed SRs 3.8.1.3 and 3.8.1.9 acceptable.

4.3 Significant Hazards Consideration Northern States Power Company, a Minnesota corporation, has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, "Issuance of amendment,"

as discussed below:

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

Response: No This license amendment request proposes to increase a portion of the Prairie lsland Nuclear Generating Plant Unit 1 emergency diesel generator's 24-month test loading, reduce the Unit 2 emergency diesel generators' monthly test loading which demonstrates Technical Specification operability and revise the 24-month test to require the Unit 2 emergency diesel generators to operate for at least 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months at 100 - 110% of the continuous rated loading and the remainder of the 24-hour test at or above 4000 kW. The proposed test loads will continue to assure that the emergency diesel generators have the necessary reliability and availability for the design basis accidents and station blackout events.

The emergency diesel generators are required to be operable in the event of a design basis accident coincident with a loss of offsite power to mitigate the consequences of the accident. They are also the alternate AC source for a station blackout on the other Prairie lsland Nuclear Generating Plant unit. The emergency diesel generators are not accident initiators and therefore these changes do not involve a significant increase in the probability of an accident previously evaluated.

The accident analyses assume that at least one safeguards bus is provided with power either from the offsite sources or the emergency diesel generators. The Technical Specification changes proposed in this license amendment request will continue to assure that the emergency diesel generators have the capacity and Page 26 of 30

Enclosure NSPM EDG Test Loads capability to assume their maximum auto-connected loads. Thus, the changes proposed in this license amendment request do not involve a significant increase in the consequences of an accident previously evaluated.

The changes proposed in this license amendment do not involve a significant increase in the probability or consequences of an accident previously evaluated.

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

Response: No This license amendment request proposes to increase a portion of the Prairie Island Nuclear Generating Plant Unit 1 emergency diesel generator's 24-month test loading, reduce the Unit 2 emergency diesel generators1monthly test loading which demonstrates Technical Specification operability and revise the 24-month test to require the Unit 2 emergency diesel generators to operate for at least 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months at 100 - 110% of the continuous rated loading and the remainder of the 24-hour test at or above 4000 kW. The proposed test loads will continue to assure that the emergency diesel generators have the necessary reliability and availability for the design basis accidents and station blackout events.

The proposed Technical Specification changes do not involve a change in the plant design, system operation, or the use of the emergency diesel generators.

The proposed changes require the Unit 1 emergency diesel generators to be tested at increased loads and allow the Unit 2 emergency diesel generator to be tested at reduced loads which envelope the required safety function loads.

These revised loads continue to demonstrate the capability and capacity of the emergency diesel generators to perform their required functions. There are no new failure modes or mechanisms created due to testing the emergency diesel generators at the proposed test loading. Testing of the emergency diesel generators at the proposed test loadings does not involve any modification in the operational limits or physical design of plant systems. There are no new accident precursors generated due to the proposed test loadings.

The Technical Specification changes proposed in this license amendment do not create the possibility of a new or different kind of accident from any previously evaluated.

Does the proposed amendment involve a significant reduction in a margin of safety?

Response: No This license amendment request proposes to increase a portion of the Prairie Island Nuclear Generating Plant Unit 1 emergency diesel generator's 24-month Page 27 of 30

Enclosure NSPM EDG Test Loads test loading, reduce the Unit 2 emergency diesel generators' monthly test loading which demonstrates Technical Specification operability and revise the 24-month test to require the Unit 2 emergency diesel generators to operate for at least 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months at 100 - 110% of the continuous rated loading and the remainder of the 24-hour test at or above 4000 kW. The proposed test loads will continue to assure that the emergency diesel generators have the necessary reliability and availability for the design basis accidents and station blackout events.

The proposed Technical Specification changes will continue to demonstrate that the emergency diesel generators meet the Technical Specification definition of operability, that is, the proposed tests will demonstrate that the emergency diesel generators will perform their safety function and the necessary emergency diesel generator attendant instrumentation, controls, cooling, lubrication and other auxiliary equipment required for the emergency diesel generators to perform their safety function loads are also tested at these proposed loadings. The proposed testing will also continue to demonstrate the capability and capacity of the emergency diesel generators to supply their required loss of offsite power loads coincident with station blackout loads from the opposite unit. Since the proposed surveillance testing will continue to demonstrate operability, and the capability and capacity to supply their required loss of offsite power coincident with opposite unit station blackout loads, the proposed Technical Specification changes do not involve a significant reduction in a margin of safety.

Therefore, the proposed changes do not involve a significant reduction in a margin of safety.

Based on the above, Northern States Power Company, a Minnesota corporation, concludes that the proposed amendment does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92(c) and, accordingly, a finding of "no significant hazards consideration" is justified.

4.4 Conclusions In conclusion, based on the considerations discussed in above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

5. ENVIRONMENTAL CONSIDERATION A review has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does not involve (i) a significant Page 28 of 30

Enclosure NSPM EDG Test Loads hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluent that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(~)(9).Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.

6. REFERENCES

1. Prairie lsland Nuclear Generating Plant; Design Report for the Station Blackout/Electrical Safeguards Upgrade Project, dated November 27, 1990.

2. Prairie lsland Nuclear Generating Plant; Design Report for the Station Blackout/Electrical Safeguards Upgrade Project, Revision 1 (TAC Nos. 68588 and 68599), dated December 23, 1991.

3. Prairie lsland Nuclear Generating Plant, Unit Nos. 1 and 2 -Amendment Nos.

103 and 96 to Facility Operating License Nos. DPR-42 and DPR-60 (TAC Nos.

M83070 and M83071), dated December 17, 1992, Accession Number ML022240504.

4. Prairie lsland Nuclear Generating Plant, Unit Nos. 1 and 2, Issuance of Amendments RE: Emergency Diesel Generator Testing Requirements (TAC Nos. M90564 and M90565), dated January 5, 1995, Accession Number ML022250357.

5. Calvert Cliffs Nuclear Power Plant, Units 1 & 2; Docket Nos. 50-317 & 50-318; License Amendment Request; Enhancement of the Engineered Safety Features, dated November 1, 1995.

6. Calvert Cliffs, Units 1 and 2, Amendments 214 and 191, Reflecting the New Plant Electrical Distribution Configuration, dated April 2, 1996, Accession Number ML010510322.

7. Prairie lsland Nuclear Generating Plant, License Amendment Request dated March 20, 1992, Auxiliary Electrical System Changes and Cooling Water System Changes.

8. Prairie lsland Nuclear Generating Plant, Unit Nos. 1 and 2, Updated Safety Analysis Report, Chapter 8.0, as updated by the corrective action program.

9. Prairie lsland Nuclear Generating Plant, License Amendment Request dated March 17, 1986, L C 0 Action Statements and Miscellaneous Changes.

Page 29 of 30

Enclosure NSPM EDG Test Loads

10. License Amendment Request (LAR) to Increase the Unit 1 Emergency Diesel Generators' (EDG) Monthly Test Load, dated August 16, 2007, Accession Number ML072320401.

Page 30 of 30

ENCLOSURE, ATTACHMENT 1 Technical Specification Pages (Markup) 2 pages follow

AC Sources-Operating SURVEILLANCE REQUIREMENTS (continued)

SURVEILLANCE FREQUENCY SR 3.8.1.3 ........................... NOTES ...........................

1. DG loadings may include gradual loading in consideration of manufacturer's recommendations.

2. Momentary transients outside the load range do not invalidate this test.

3. This Surveillance shall be conducted on only one DG at a time.

4. This SR shall be preceded by and immediately follow without shutdown a successful performance of SR 3.8.1.2 or SR 3.8.1.6.

3 1 days Verify each DG is synchronized and loaded and operates for 2 60 minutes at a load:

a. Unit 1; > 2500 kW; and

b. Unit 2; 2 $!>OQSKK) k W 4 5 5 M .

SK 3.8.1.4 Verify fuel oil level above lower limit switch in each 3 1 days day tank.

SR 3.8.1.5 Verify the fuel oil transfer system operates to transfer 3 1 days fuel oil from storage tank to the day tank.

Prairie Island Unit 1 - Amendment No. 475 4-87 tinits 1 and 2 3.8.1-7 Unit 2 - Amendment No. 4 4 9 4-65

AC Sources-Operating SURVEILLANCE REQUIREMENTS (continued)

SURVEILLANCE FREQUENCY SR 3.8.1.9 ............................ NOTE---------------------------

Momentary transients outside the load range do not invalidate this test.

Verify each DG operates for 2 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months s: 24 months

a. For 2 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months loaded:

Unit 1 2 2832 kW, and

< 3000 kW Unit 2 > 54005-W kW, and

< 5940 kW; and

b. For the remaining hours of the test loaded:

Unit 1 2 25002475 kW, and Unit 2 > 4 0 0 0 M kW; and

c. Achieves steady state voltage 2 3740 V and 5 45 80 V; and frequency 2 58.8 Hz and 5 6 1.2 Hz.

Prairie Island Unit 1 - Amendment No. 4-58 Units 1 and 2 Unit 2 - Amendment No. 4-49

ENCLOSURE, ATTACHMENT 2 Bases Pages (Markup)

(For Information Only) 3 pages follow

AC Sources-Operating B 3.8.1 BASES SURVEILLANCE SR 3.8.1.2 and SR 3.8.1.6 (continued)

REQUrRErn Since SR 3.8.1.6 requires a 10 second start, it is more restrictive than SR 3.8.1.2, and it may be performed in lieu of SR 3.8.1.2. This is the intent of Note 1 of SR 3.8.1.2.

The 3 1 day Frequency for SR 3.8.1.2 and the 184 day Frequency for SR 3.8.1.6 provide adequate assurance of DG OPERABILITY, while minimizing degradation resulting from testing.

This Surveillance verifies that the Unit 1 DGs, D 1 and D2, are capable of synchronizing with the offsite electrical system and accepting loads greater than or equal to 90% of the continuous rating of the DG-@&elf;2). This S_u_vcillanc~vcrifies that thc IJnit 2 I)Gs I

arc capable of' s y ~ ~ c h ~ n i z i n g ~thc w i offsitc-dsctr-ical-systc~n th and accepting loads-greater than the DHA loads or the licensing basis station blackout loads. The Unit 1 and Unit 2 diesel generators have different loading requirements since their individual loads are different. As an example, the Unit 2 diesel generators supply emergency power to the cooling water pump whereas the Unit 1 diesel do not. A minimum run time of 60 minutes is required to stabilize engine temperatures, while minimizing the time that the DG is connected to the offsite source.

The 3 1 day Frequency for this Surveillance is consistent with SR 3.8.1.2.

This SR is modified by four Notes. Note 1 indicates that diesel engine runs for this Surveillance may include gradual loading, as recommended by the manufacturer, so that mechanical stress and wear on the diesel engine are minimized. Note 2 states that momentary transients, because of changing loads or system Prairie Island Unit 1 - Revision 4-97 Units 1 and 2 B 3.8.1-17 Unit 2 - Revision 4-97

AC Sources-Operating B 3.8.1 BASES SURVEILLANCE SR 3.8.1.8 (continued)

REQUIREMENTS The noncritical trips are bypassed during DBAs and provide an alarm on an abnormal engine condition. This alarm provides the I

operator with sufficient time to react appropriately. The DG availability to mitigate the DBA is more critical than protecting the engine against minor problems that are not immediately detrimental to emergency operation of the DG.

The 24 month Frequency is based on engineering judgment, taking into consideration unit conditions required to perform the Surveillance, and is intended to be consistent with expected he1 cycle lengths. Operating experience has shown that these components usually pass the SR when performed at the 24 month Frequency. Therefore, the Frequency was concluded to be acceptable from a reliability standpoint.

Demonstrate once per 24 months that the DGs can start and run continuouslyorf- an interval of not less than 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months , 2 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months of which is at a load equivalent to 103 - 110%

f the continuous duty rating and the remainder of the time at a load equivalent to the design basis accident--l o a d i r ~ g & m ~ a - t ~ of the DG. The DG starts for this Surveillance can be performed either from standby or hot conditions. The provisions for prelubricating and warmup, discussed in SR 3.8.1.2, and for gradual loading, discussed in SR 3.8.1.3, are applicable to this SR.

Prairie Island Unit 1 - Revision 78 Units 1 and 2 Unit 2 - Revision 4-70

AC Sources-Operating B 3.8.1 BASES (continued)

REFERENCES 1. AEC "General Design Criteria for Nuclear Power Plant Construction Permits," Criterion 39, issued for comment July 10, 1967, as referenced in the USAR, Section 1.2.

2.

fikwsm~4Not used.

3. USAR, Section 14.

Prairie Island Unit 1 - Revision 4-97 Units 1 and 2 Unit 2 - Revision 4-97

ENCLOSURE, ATTACHMENT 3 Technical Specification Pages (Retyped) 2 pages follow

AC Sources-Operating SURVEILLANCE REQUIREMENTS (continued)

SURVEILLANCE FREQUENCY SR 3.8.1.3 ........................... NOTES ...........................

I . DG loadings may include gradual loading in consideration of manufacturer's recommendations.

2. Momentary transients outside the load range do not invalidate this test.

3. This Surveillance shall be conducted on only one DG at a time.

4. This SR shall be preceded by and immediately follow without shutdown a successfbl performance of SR 3.8.1.2 or SR 3.8.1.6.

3 1 days Verify each DG is synchronized and loaded and operates for 2 60 minutes at a load:

a. Unit 1; 2 2500 kW; and

b. Unit 2; 2 4000 kW.

SR 3.8.1.4 Verify fuel oil level above lower limit switch in each 3 1 days day tank.

SR 3.8.1.5 Verify the he1 oil transfer system operates to transfer 3 1 days fuel oil from storage tank to the day tank.

Prairie Island Unit 1 - Amendment No. 4-75 4-87 (inits 1 and 2 3.8.1-7 Unit 2 - Amendment No. 449 I-65

AC Sources-Operating 3.8.1 SURVEILLANCE REQUIREMENTS (continued)

SURVEILLANCE FREQUENCY SK 3.8.1.9 ............................ NOTE ...........................

Momentary transients outside the load range do not invalidate this test.

VerifjJ each DG operates for 2 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months s: 24 months

a. For > 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months loaded:

Unit 1 2 2832 kW, and

< 3000 kW Unit 2 1 5400 kW, and

< 5940 kW; and

b. For the remaining hours of the test loaded:

Unit 1 2 2500 kW, and Unit 2 2 4000 kW; and

c. Achieves steady state voltage 2 3740 V and 5 45 80 V; and frequency 2 58.8 Hz and 5 61.2 Hz.

Prairie Island Unit 1 - Amendment No. 4-58 lJnits 1 and 2 Unit 2 - Amendment No. 4-49

v t e Letter Sequence Request
TAC:ME0086, (Approved, Closed)
Initiation Request, Request Acceptance... Supplement Administration Meeting, Meeting, Meeting, Meeting Questions 26 June 2009 Answers Results Approval Other: ML083390695, ML101790452
MONTHYEAR2009-07-08 [Table View]

L-PI-08-080, License Amendment Request (LAR) to Revise Emergency Diesel Generator (EDG) Test Loads in Surveillance Requirement (SR) 3.8.1.3 and SR 3.8.1.9

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Enclosure:

SUMMARY

2.2 Background

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L-PI-08-080, License Amendment Request (LAR) to Revise Emergency Diesel Generator (EDG) Test Loads in Surveillance Requirement (SR) 3.8.1.3 and SR 3.8.1.9

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Enclosure:

SUMMARY

2.2 Background

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