ML20087A583

Forwards Response to NRC 840104 Request for Addl Info Re Util 831230 Application for Change to Diesel Generator/River Water Tech Specs

ML20087A583
Person / Time
Site:	Farley
Issue date:	03/02/1984
From:	Clayton F ALABAMA POWER CO.
To:	Varga S Office of Nuclear Reactor Regulation
References
NUDOCS 8403080148
Download: ML20087A583 (8)

Text

_ __- _-____,

Malling Address

- Alibima Power Company 600 North 18tn Street Post Office Box 2641 Birmingham, Alabama 35291 Telephone 205 783-6081 F. L Clayton, Jr.

Semor Vice President Flintndge Building AlabamaPower the sourtem vectrc system March 2, 1984 Docket Nos. 50-348 50-364 Mr. S. A. Varga, Chief Operating Reactors Branch #1 Division of Licensing l

U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Joseph M. Farley Nuclear Plant - Units 1 and 2 Response to NRC Request for Additional Information -

River Water / Diesel Generator Testing l

l

Dear Mr. Varga:

l In response to the Alabama Power Company request for a permanent change l

to the River Water and Diesel Gener cor Technical Specifications dated l

December 30, 1982, the NRC Staff requested additional information by letter i

dated January 4,1984. Attached is the Alabama Power Company response to the NRC Staff request for additional infor:aation.

If there are any questions, please advise.

Yours very truly, l

. L. Clayton, f-

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FLCJ r/CJS:ddr-D7 Attachment cc: Mr. R. A. Thomas Mr. G. F. Trowbridge Mr. J. P. O'Reilly Mr. E. A. Reeves Mr. W. H. Bradford i

8403080148 840302 PDR ADOCK 05000348 P

PDR

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l

Attachment Response to NRC Request for Additional Information Dated January 4,1984 NRC Request 1.

Table 1 of the December 30, 1982 submittal (which was taken from Table 8.3-3 of the FSAR) provides the maximum estimated automatically sequenced loads on the diesel generators. However, on page five of the cover letter, it is stated that deletion of the river water pumps will enable the operator to manually load the diesel generators with significant non-automatic loads. Therefore, provide the maximum expected loads for each diesel generator (this includes both automatic loads and loads which can be manually added and are not prohibited by plant procedures).

In addition, estimate the maximum time that each diesel generator will operate above the continuous rating.

APCo Response 1.

The intent of the statement made on page five of the December 30, 1982 letter was to indicate that the requested change would provide a secondary benefit of allowing the operator the capability of manually loading the diesel generators wf th non-automatic loads and still operate near or below the continuous rating of the diesel generators. The primary benefit of deleting the River Water Pumps is that it eliminates an automatically sequenced load on the diesels, thereby ensuring that the diesel generators will operate at or near their continuous rating, rather than above their continuous rating which is now the case for two of the diesels. As described in the December 30, 1982 letter, diesel generator 1C would exceed the continuous rating by 46 KW following deletion of the river water system.

In an effort to further reduce diesel generator IC's automatically sequenced loads below its continuous rating, a review cf the load studies for various conditions was conducted. The maximum loading for diesel 1C would occur during postulated event No. 3 (See FSAR Table 8.3-2, Sheet 3 of 7) which is two unit operation with a LOSP on both units and a LOCA on Unit 2.

The FSAR load study assumes the 600V Bus IK (specifically MCC 1K and Screen Wash Pump) is to be powered from Unit 1 (i.e., DG 1C) during two unit operation. The results of the reevaluation indicate that by changing plant procedures, MCC1K and Screen Wash Pump loads of the 600V Bus IK can be electrically aligned to Unit 2 (i.e., DG 1-2A). The existing and proposed electrical alignment is shown in Figure 1.

With the above procedural change in place, the 1C diesel generator and therefore all five diesel generators would be below the continuous rating for all automatically sequenced loads during analyzed events. The procedure change will be accomplished pursuant to 10CFR50.59. Procedures exist at the Farley Nuclear P1 ant which preclude operators from manually loading the diesel generators above their continuous rating except in the case of emergencies beyond those

- described in the FSAR or except as required by current surveillance test requirements.

m-ny

Attachment Page 2 The maximum expected load at which the diesel generators would be operated assuming approval of the December 30, 1982 request and after electrical realignment of MCC 1K and Screen Wash Pump loads would be:

Without River

• Cuntinuous 2000 Hour With River

• Water Pumps and D.G.

Rating (KW) Rating (KW) Water Pumps (KW) Load Realignment (KW) 1-2A 4075 4353 4348 (1,4) 3915 (6)#

1B 4075~

4353 3974 (2,5) 3974 (2,5) 2B 4075 4353 3897 (3,5) 3897 (3,5)

IC 2850 3100 3092 (1,2) 2781 (3) 2C 2850 3100 2523 (1,2,3) 214 ( All events)#

• Nu.abers in parentheses reflect FSAR Table 8.3-2 sheet numbers.

1. The previous submittal identified the greatest load for two unit operati on. The current identified loads represent the maximum possible automatic sequenced loads for the indicated event (s).

Since the proposed change would result in the diesel generator loads being below their continuous rating, an estimate of the time that the diesel generators will operate above their continuous rating is not required.

NRC Request 2.

The current Farley -Technical Specifications require that the entire 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> load test be performed at the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> rating. This is because:

(1) the maximum estimated automatic loads on two of the five diesel generators is above the continuous rating; (2) the automatic loads have

= been conservatively calculated to fall below the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> rating for each diesel generator; ar.d (3) the plant's procedures prohibit operator action from manually loading the diesel generators above the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> rating.

Technical Specification changes now under consideration propose limiting the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> load test to a value at or near the continuous rating. We believe that the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> load test should envelop the worst case conditions for each diesel generator. In addition, we believe that each diesel generator should be run for a minimum of two hours at the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> rating during each test. This provides a verification of their load carrying capability with some margin for uncertainties. Therefore, propose 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> load tests that demonstrate that each diesel generator meets the above criteria. Also provide assurance that written procedures exist to restrict manual loading of the diesel generator following a

~ transient so that the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> load test envelops the worst ::ase transients.

s Attachment Page 3' APCo Response 2.

As stated in answer to question 1 above, maximum loading for all diesel generators will be the continuous rating once the proposed change is approved and the MCC 1K and Screen Wash Pump loads are realigned.

Existing plant procedures state that diesel _ generators may not be manually loaded above the continuous rating except in the case of emergencies beyond those described in the FSAR or except as required by

' current surveillance test procedures. The resulting margins for each Ldiesel generator are as follows:

Diesel Continuous Maximum Sequenced

• Generator Rating (KW)

Load Without RWS (KW) % Margir 1-2A 4075 3915 (6) 4.1 1B-4075 3974 (2,5) 2.5 2B 4075

'3897 (3,5) 4.6 1C 2850 2781 (3) 2.5 2 C --

2850 214 ( All events) 1230

• Numbers in parentheses reflect FSAR Table 8.3-2 sheet numbers.

The diesel generator manufacturer does not recommend exceeding the continuous rating for test purposes. Exceeding the continuous rating

during testing could result in diesel generator degradation.

It is the opinion of Alabama Power Company that deletion of the river water system and realignment of above mentioned electrical loads results in acceptable load carrying capaoility with adequate margin when tested

. at the continuous rating.

NRC-Request 3.

The present Technical Specifications require that following the successful completion of the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> load test, the diesel generator be tripped from the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> load condition and a hot restart be performed within ten minutes.

It is stated in the December 30, 1982 letter, that tripping the diesel generator from the 2000 hour0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> test load conditions could cause difficulties with the hot restart test due to the diesel

generator control settings. Therefore, a Technical Specification change has been proposed so that following the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> load test, the diesel generator can be manually reduced in power prior to the trip 'and hot restart test.

f Since it has been proposed to conduct the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> load test at essentially the continuous rating, it is not clear that the above concern still exists. Therefore, provide a discussion that further justifies why the diesel generator must be manually reduced in load before being tripped.

~_ -

. Attachment

'Page 4' APCo Response

-3._

The need for unloading the diesel generators at the conclusion of the 24

_ hour test but before the hot restart test still exists. During the 24

- hour load test the diesel generator is paralleled to the grid.

Paralleling the generator consisti of synchronizing the generator to the grid, closing the output breakers, and then advancing the governor and exciter control settings until the desired load is achieved.

If, after the successful completion of the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> load test, the diesel generator is tripped from any significant load condition, the governor

.and exciter controls will remain at those load settings. When the start signal is'given for the hot restart test, the diesel generator will start and accelerate to the speed and voltage determined by the governor i

and exciter settings. Since these settings are for the previous load condition and _the diesel generator is not loaded during the hot restart

. test, the voltage and frequency at the generator output will be high and the diesel generator may trip on overspeed.

It is emphasized that the limitation described above applies only for surveillance testing which requires paralleling the diesel generators with the grid. The above limitation does not apply to the restart of a tripped diesel generator

'during a loss of offsite power (LOSP) event.

If, however, the diesel generator is unloaded by reducing the governor and exciter settings prior to tripping at the end of'the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> load test, the control settings would then be set properly for the hot restart test.

The diesel generator manufacturer recommends that the diesel generator

load be _ reduced at discrete load plateaus for recommended time periods following load testing in order to provide adequate time to cooldown the engine. : Requiring the diesel generator to be tripped from loaded conditions can cause " baking" of the lubricating oil with a varnish type buildup with resultant dry spots on lubricated surfaces. Since the engine driven ' lubricating oil and jacket water cooling pumps are shutdown-when the diesel generator is shutdown, the_ engines latent heat

~1s not adequately transferred. However, by following the manufacturer's cooldown/ shutdown recommendations, the potential for experiencing the

. above deleterious effects, which could precipitate a condition of inadequate lubrication, is virtually eliminated.

It is Alabama Power Company's understanding that-the rationale behind the NRC's position for requiring _a. loaded trio and subsequent qdick restart is that the ~ diesel generator should be demonstrated to be capable lof a hot restart in the event of-a trip during operation.

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Attachment Page 5 Should, however, a diesel generator trip during either a test or an actual LOSP, it would not be prudent, based on past experience and the manufacturer's recommendations, to attempt a restart before the reason for the trip has been identified and corrected. As a matter of clarification, Alabama Power Company considers the ten (10) minute time

' limit specified for hot restart testing in the December 30, 1982 letter (Techr.ical Specification 4.3.1.1.2.c.5) to begin after the diesel generator has been unloaded and tripped in accordance with the manufacturer's recommendations.

In conclusion, Alabama Power Company strongly objects to the requirement to trip a diesel generator from a loaded condition.

This condition, which is not in accordance with vendor recommendations, could be detrimental to the reliability of the diesel generators and therefore could advarsely impact plant safety.

It is emphasized that the need for unloading the diesel generators (at the conclusion of the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> load tests) in accordance with the vendor's shutdown recommendations exists regardless of the extent to which the diesel generator is loaded during c

the test and regardless of che results of the remainder of the proposed river water / diesel generator technical specification review.

NRC Request

'4.

Section 9.3.4 of the staff's original Safety Evaluation Report for Farley Units 1 and 2 (published in May 1975) discusses the ultimate heat sink. - This'section discussed the initial and periodic tests that would be perfonned to verify the design supply of water for the ultimate heat sink. At that time, the staff concluded that the proposed testing would not adequately verify the capability of the pond to serve as the ultimate heat sink.

Considering that deleting the river water pumps from the Technical Specifications will result in the pond being the ultimate heat sink, provide a discussion that describes how periodic testing has, and will continue to verify, the heat removal capability of the pond to serve as the ultimate heat sink.

APCo Response 4.

The Farley Service Water Pond Technical Specifications include four surveillance requirements in section 3/4.7.6 as described below:

(1) The water temperature and water icvel are verified to be within limits which ensures that sufficient cooling capacity is available to mitigate the effects of accident conditions.

.~

Attachment Page 6 (2) The spillway channel and adjacent areas are verified to be free of erosion damage after each storm that raises the pond level greater than or equal to 187', mean sea level. This verification ensures that the pond level will not be decreased due to spillway

-degradation.

(3) The spillway channel and structure are verified to be intact at least once every 2 years to ensure that the pond level will not be decreased due to spillway degradation.

(4) The ground water seepage from the pond is determined to be less than 15 cfs at least once per 5 years. This determination will ensure that the service water pond can adequately function as the plant ultimate heat sink independent of the river water system.

The NRC concluded in the original Farley SER that the then proposed initial and periodic tests on the service water pond were inadequate to verify the pond's capability to serve as the plant ultimate heat sink.

As documented in SER subsection 2.5.3 and section 16.0, the NRC required the

-following technical specification additions to resolve this issue:

Item 1.

a special report from Alabama Power providing the result of preoperation tests to determine water loss by seepage from the pond, and Item 2.

a periodic surveillance requirement to detect large increases in water loss by seepage.

Alabama Power conducted a preoperational test on the service water pond in accordance with the test procedure outlined in FSAR subsection 14.1.2.

The test verified the pond seepage to be considerably lower than the seepage value assumed in the FSAR pond heat sink analysis.

The NRC received the test results, found them acceptable, and subsequently detemined that the need for the special report had been satisfied and was no longer required. A discussion of these actions can I

be found in sections 14.0 and 16.0 of Supplement 3 to the Farley SER.

At the same time, Alabama Power added surveillance requirement (4) above to the technical specifications to periodically verify that the pond's ability.to hold water is not degraded by increases in the seept.ge rate.

This change was acknowledged by the NRC in SER Supplement 3, section 16.0.

With this additional surveillance requirement, the periodic testing program at Farley has and will continue to wrify that the service water pond can, independant from the river..er system, adequately perform the ultimate heat sink function.

Figure 1 Existing and Proposed Electrical Alignment of MCC 1K and Screen Wath Pump Train A Train A Un' t1 Uni <. 2 C

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Cm MCC Screen Wash 1K Pump Existing Electrical Alignment Train A Train A Unt 1 Un' t2 e.

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C

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MCC Screen Wash 1K-Pump Proposed Electrical Alignment Key 0 - breaker open C - breaker closed 4

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