ML20237G346

Application for Amends to Licenses DPR-57 & NPF-5,changing Tech Specs to Allow Continued Operation at Suppression Pool Temps of Up to 100 F When River Temp in Excess of 87 F.Fee Paid

ML20237G346
Person / Time
Site:	Hatch
Issue date:	08/14/1987
From:	James O'Reilly GEORGIA POWER CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML20237G349	List: ML20237G346 ML20237G351
References
SL-3040, TAC-65987, TAC-65988, NUDOCS 8708240053
Download: ML20237G346 (13)

Text

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, Georgia Power Company 373 Piedmont Avenue a'

Atlanta, Georgia 30308 Telephone 404 526-7851 M$thng Addrets' Nst Office Box 4545 Alianta. Georgia 30302 o V ce i dont Nuclear Operabons SL-3040 1596C X7GJ17-H600 August 14, 1987 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 PLANT HATCH - UNITS 1, 2 NRC DOCKETS 50-321, 50-366 OPERATING LICENSES DPR-57, NPF-5 REQUEST TO REVISE TECHNICAL SPECIFICATIONS:

SUPPRESSION POOL TEMPERATURE LIMIT Gentlemen:

In accordance with the provisions of 10 CFR 50.90, as required by '

10 CFR 50.59(c)(1), Georgia Power Company hereby proposes changes to the Plant Hatch Units 1 and 2 Technical Specifications, Appendix A to Operating Licenses DPR-57 and NPF-5.

Technical Specifications for both Plant Hatch Units provide a  !

l limiting condition for operation (LCO) requiring plant shutdown in the event that suppression pool temperature exceeds 950F. Due to extremely high temperatures in Georgia, the temperature of the Altamaha River, which serves as the ultimate heat sink for the plant service water and ]

residual heat removal systems, has risen to the point where sufficient differential temperature is not available to effectively maintain the suppression pool temperature below 950F. Suppression pool temperatures are currently near 940F for both units. On August 10, 1987, the LC0 for Plant Hatch Unit 2 was entered for several hours, but was cleared prior to commencement of plant shutdown.

l l Since the current hot, seasonal temperatures are expected to ,

continue, there is a significant probability that the LC0 will again be l l entered in the near future. Should this situation occur, in order to l

avoid plant shutdown during the present period of peak electrical demand, l Georgia Power Company (GPC) hereby requests Technical Specifications I changes for both units which will allow continued operation at suppression pool temperatures of up to 1000F, when river temperature is jM**iB85 SISS$P ool go l

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U.S. Nuclear Regulatory Commission August 14, 1987 Page Two in excess of 870F. These changes are requested on an emergency basis, pursuant to the provisions of 10 CFR 50.91 (a)(5), in that failure to act in a timely manner could result in the shutdown of both Hatch units.

He request that the proposed change be in effect until September 30, 1987, by which time it is expected that river temperature will decrease '

sufficiently. The requested change does not require an environmental impact statement.

Enclosure 1 provides a detailed description of the proposed changes and the bases for the changes.

Enclosure 2 provides a General Electric safety evaluation for Plant Hatch justifying deleting the operating limit-suppression pool limit of 95'F. (The analyzed change bounds the requested change.)

Enclosure 3 details the bases for our determination that the proposed changes do not involve a significant hazards consideration.

Enclosure 4 provides page change instructions for incorporating the proposed changes.

The proposed changed Technical Specifications pages follow Enclosure 4.

Payment of a filing fee in the amount of one hundred and fifty dollars is enclosed.

Pursuant to the requirements of 10 CFR 50.91, a copy of this letter '

and all applicable enclosures will be sent to Mr. J. L. Ledbetter of the Environmental Protection Division of the Georgia Department of Natural Resources.

1596C

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r U.S. Nuclear Regulatory Commission-August 14, 1987 Page Three Mr. James P. O'Reilly states that he is Senior Vice President of Georgia Power Company and is authorized to execute this oath ~ on behalf of Georgia Power Company, and that to the best of his knowledge and belief, the facts set forth in this letter and enclosures are true.

GEORGIA POWER COMPANY By: \ nwA ~

(7 kX James P. O'Reilly . (

Sworn to and-subscribe before me thi b h a of August 1987k 8 vM =m *

(I__ _

$1a.19s7 Notary Public GKM/lc

Enclosures:

1. Basis'for Change Request

2. General Electric Safety Evaluation

3. 10 CFR 50.92 Evaluation

4. Page Change Instructions

5. Filing Fee - $150.00 c: Georaia Power Company Mr. J. T. Beckham, Jr., Vice President Plant Hatch GO-NORMS-U.S. Nuclear Regulatory Commission. Washinaton. D.C.

Mr. L. P. Crocker, Licensing Project Manager - Hatch U.S. Nuclear Reaulatory Commission. Reaion II Dr. J. N. Grace, Regional Administrator Hr. P. Holmes-Ray, Senior 'tesident Inspector - Hatch State of Georaia Mr. J. L. Ledbetter, Commiss'ioner - Department of Natural Resources 1596C

y ENCLOSURE-1 PLANT HATCH - UNITS 1, 2 NRC DOCKETS 50-321, 50-366 OPERATING LICENSES DPR-57, NPF-5 REOUEST TO REVISE TECHNICAL SPECIFICATIONS:

l SUPERESS10tLE00L TEMPERATURE LIMIT BASIS FOR CHANGE REOUEST PROPOSED CHAN(iES:

The proposed amendments to the Unit 1 and the Unit 2 Technical '

Specifications would raise the allowable operating temperature of the suppression pool from 950F to 1000F, for those periods when the temperature of the Altamaha river, as measured at the Plant Hatch intake structure, exceeds 870F. The suppression pool temperature limit (SPTL)  ;

l. requiring plant shutdown (110'F)'and vessel depressurization (120*F) will remain unchanged. The generic analyses performed for the Boiling Water Reactor Owner's Group (BWROG) SPTL Committee and a Plant Hatch-specific evaluation performed by General Electric Company (Enclosure 2) have shown that design basis requirements are satisfied as long as the operating limits are less than the 110'F SPTL requiring immediate shutdown.

Basis for Proposed Changes:

Historically, the suppression pool temperature limit for normal operation has been chosen based on the maximum expected service water temperature, for Plant Hatch this is 950F. There are many licensing analyses that utilize this pool temperature as the initial condition. Generic evaluations performed for the BHROG SPTL Committee have shown that the normal operating suppression pool temperature limit for BHRs with Mark I Containments can be raised to 1100F with no adverse impact on safety.

The following addresses the impact of raising pool temperature on existing Plant Hatch safety analyses. The evaluation includes assessment of Anticipated Transient Hithout Scram (ATHS) events and Emergency Procedure Guidelines (EPGs), even though these areas are beyond the historical design basis of the plant General Electric Topical Report NEDO 30832 " Elimination of Limit on BWR Suppression Pool Temperature for SRV Discharge With Quenchers", dated ,

December 1984, and General Electric's evaluation provided as Enclosure 2 to this letter, detail the results of these evaluations. The key conclusions from the evaluations are presented below.  !

1596C El-1 8/14/87 SL-3040

1 ENCLOSURE 1 (Continued)

REOUEST TO REVISE TECHNICAL SPECIFICATIONS:

SUPPRESSION POOL TEMPERATURE LIMIT BASIS FOR CHANGE RE0 VEST

1. Bases for Current SPTL The current Technical Specifications limit of 95'F was based upon the maximum expected service water temperature and specifies the SPTL for full-power operation. Since plant shutdown is required if the temperature exceeds 95'F for an 8-hour period, the suppression pool cooling mode of the residual heat removal (RHR) system is initiated at a pool temperature below 95'F. The current 95'F limit is an initial condition for several containment evaluations, including long-term pressure and temperature response, and dynamic condensation loads. The proposed changes would raise this SPTL during periods of high river temperature.

Presently a SPTL of 110*F is specified if reactor power becomes greater than 1 percent. This " scram limit" was correlated to the suppression pool size and bulk-to-local pool temperatures experienced during high-mass flux safety relief valve (SRV) discharge. The limit was developed based on concerns relative i to unstable steam condensation at elevated pool temperatures through discharge devices without quenchers (i.e., rams head).

During a postulated ATHS event, Plant Hatch Emergency Operating Procedures (EOPs) call for the initiation of boron injection.

The proposed changes to the Technical Specifications would not modify this limit.

A pool temperature of 120*F requires depressurization of the reactor pressure vessel (RPV). The basis of this SPTL was similar to the scram limit, i.e., to avoid concerns relative to the unstable condensation through rams head SRV discharge devices at high pool temperatures at elevated RPV pressure. The proposed changes to the Technical Specifications would not modify this limit.

2. Imoact Voon Safety Evaluations The Plant Hatch suppression pool was sized to accept the decay and sensible heat resulting from a postulated loss-of-coolant accident (LOCA). Extensive evaluations have been performed on the drywell and wetwell pressure temperature response, as well as the containment dynamic response to various LOCA and SRV discharge loads. The postulated LOCA dynamic loading would 1596C El-2 8/14/87 SL3040

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L ENCLOSURE 1 (Continued)

RE0 VEST TO REVISE TECHNICAL SPECIFICATIONS:

SUPPRESSION POOL TEMPERATURE LIMIT BASIS FOR CHANGE REOUEST begin with the purging of air from the drywell to the wetwell  !

free space'via the vent /downcomer system. For large breaks, the air blowing into the drywell causes a bulk movement of the water into the wetwell free space (i.e., pool swell). An increase in the initial pool temperature would not affect the " pool swell" load significantly.

After the air is purged from the drywell, a period of .

steady-steam condensation occurs at the downcomer/ suppression pool interface -(condensation oscillation) which would create a sinusoidal loading on the containment structure. After the mass flux from the drywell decreases, unsteady condensation may occur, resulting in a steam bubble collapse at the dowacomer/ pool interface. -This regime is called " chugging." l From a safety analysis standpoint, it is necessary to show that an increase in the initial suppression pool temperature will not increase containment loads above the design loads assumed in the Plant Hatch containment design evaluations. The hydrodynamic ,

portion of these loads was developed from a series of full-scale l tests simulating _ a variety of LOCAs. Because the tests were developed to bound all BWR plants with Mark I containments, the hydrodynamic parameters selected for the test facility were extremely -conservative. For condensation oscillation loads, General Electric developed a correlation to relate the magnitude of the load with pertinent hydrodynamic parameters, e.g., mass '

flux, vent /downcomer length, and pool temperature.

Consideration of Plant Hatch-specific bounding hydrodynamic parameters would result in an oscillatory load which is less than that assumed in the containment loads evaluation even with .

I a pool temperature of 110 degrees (the shutdown limit). The full-scale load tests have shown that chugging occurs only with small-break LOCAs and relatively low pool temperatures. An increase in the operating SPTL will have no impact upon chugging i design loads.

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The impact of an increase in the operating suppression pool temperature on SRV design loads has been assessed. As with postulated LOCA loads, the event can be divided into air-clearing loads and condensation loads. Air-clearing loads result from the expulsion of air out of the SRV discharge line  ;

into the suppression pool. The expansion and contraction of the  :

air bubble creates an oscillatory loading on the containment  !

1596C El-3 8/14/87 SL-3040

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.i ENCLOSURE 1 (Continued)

.REOUEST TO REVISE TECHNICAL SPECIFICATIONS:

E SUPPRESSION P0OL TEMPERATURE LIMIT BASIS FOR CHANGE REOUEST wall and submerged structures. This loading increases slightly with higher initial pool temperature; however, as detailed in the safety evaluation (Enclosure 2), the bounding ' Mark I load case is the first actuation of an SRV at a pool temperature consistent with RPV depressurization (120*F). As stated previously, the scram and depressurization pool temperature limits were specified by the NRC in NUREG-0783 because of concerns regarding unstable condensation. GE topical report NEDO - 30832, which has been previously submitted , by the BWROG, justifies the ' removal of pool temperature limits for SRV i discharge for plants with quencher devices, such as Plant i Hatch. The report shows that SRV condensation loads are low as compared with other containment loads, e.g., the SRV air-clearing load.

The pressure and temperature design limit for Plant Hatch were compared to the maximum predicted containment pressures and temperatures during a LOCA both with the current pool temperature limit and the proposed limit. Due to the very high- '

containment temperature and pressure design limits given for Mark I containments, large increases in the operational pool ,

temperature limit would have a negligible impact on the existing  ;

analytical results. Net Positive Suction Head (NPSH)  !

requirements for safety system pumps have been reviewed. At the slightly higher peak suppression pool temperatures (caused from higher initial pool and service water temperature), NPSH requirements are satisfied.

The ECCS calculations for Plant Hatch were reviewed regarding the slightly higher temperature of the water which would be injected into the core following a postulated LOCA. The impact was determined to have a negligible effect on the calculated peak clad temperature.

3. Imoact Uoon E0Ps and ATHS Evaluations The Plant Hatch E0Ps (currently based upon Revision 3 of the EPGs) take credit for the analyses presented in NEDO 30832. The Revision 4 EPGs also eliminate any pool temperature limits associated with SRV discharge. The proposed changes to the Technical Specifications would modify only the operating SPTL and, therefore, would not affect the E0Ps. Since the design 1596C El-4 8/14/87 SL-3040

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i ENCLOSURE.1-(Continued)

RE00EST TO REVISE TECHNICAL SPECIFICATIONS:

SUPPRESSION POOL TEMPERATURE LIMIT-BASIS FOR CHANGE REOUEST evaluations for ATHS were performed using "best" estimate inputs rather than " bounding" inputs, they would be unaffected by a change to the operating pool temperature limit. The pool temperature at which the operator is instructed to start boron i injection during a postulated ATHS event is 1100F, and would {

not be'affected per this proposed amendment. j l

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1 ENCLOSURE 2 GENERAL ELECTRIC COMPANY SAFETY EVALUATION SUPPRESSION POOL TEMPERATURE LIMIT NOTE: General Electric Company, the NSSS vendor for Plant Hatch and conceptual designer of the Mark I suppression pool containment, was requested by GPC to prepare an evaluation addressing deletion of the 950F operating limit for. suppression pool temperature for Plant Hatch.

This evaluation, which supports a limit of 1100F (and thus bounds the requested change) was received by letter of August 10 1987, and is hereby provided:

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1. Background The suppression pool temperature limit for normal operation has historically been chosen based on the maximum expected service water ,

temperature. For Plant Hatch this is 950F. There are many licensing analyses that utilize this pool temperature as the initial condition. Generic evaluations performed for the BHROG Suppression Pool Temperature Limit (SPTL) Committee have shown that the normal operating suppression pool temperature limit for BHRs with Mark I Containments can be raised to 1100F, the maximum temperature for operation at power greater than 1% (scram limit). The following summarizes these evaluations and discusses their application to Plant Hatch.

Events which involve the suppression pool can be divided into two general categories: Safety Relief Valve (SRV) discharge to the pool via the SRV discharge lines and T-Quenchers, and discharges to the pool via the drywell to wetwell vent pipes during design basis loss-of-coolant accidents (LOCA). The following discussions show .

that the pool temperature limit for normal operation can be '

increased without affecting plant safety for discharges of either l category.

2. SRV OoeratinD 2.1 SRV Air Clearing Loads SRV air-clearing loads on the pool boundary and submerged structures are sensitive to pool temperature. The U. S. Mark I Containment Program procedure for analysis of air-clearing loads specifies that the limiting load case is the first actuation at the maximum pool temperature permitted with the reactor vessel (RPV) at the operating pressure. Mark I plants (including Plant Hatch) have a pool temperature Technical Specification limit of 1200F with the RPV at pressure (i.e., depressurization of the RPV is required if the pool 1596C E2-1 8/14/87 SL-3040

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ENCLOSURE 2 (Continued)

SAFETY EVALUATION l SUPPRESSION POOL TEMPERATURE LIMIT temperature ~ exceeds 1200F). Therefore, the limiting SRV i' air-clearing load case for Mark I plants is a first actuation at a pool temperature of 1200F. An increase in the normal ~ operating temperature to 1100F for Plant Hatch will not affect this design load.

2.2 SRV Condensation Loads Domestic BWRs have quenchers at the discharge end of the safety relief valve discharge lines to reduce the amplitude of the dynamic loads resulting from steam condensation in the suppression pool during SRV discharge. The Plant Hatch Units have T-Quenchers designed by General Electric. >

The BHROG SPTL Committee Phase 1 work, documented in NED0-30832, justifies the increase in the pool temperature limit for normal l operation. This report showed that a pool temperature limit was not required for SRV discharges through quenchers. This report has been submitted to the NRC. 4 3.0 LOCA REL6TED CONTAINMENT LOADS To address the effect of increased pool temperatures on Mark I containment loads during a LOCA, analyses were conducted on a generic basis for the BWROG SPTL Committee. A maximum allowable operational (initial LOCA) pool temperature was developed from these analyses which ensured that: 1) containment pressures and temperatures do not exceed design values, and 2) hydrodynamic loads during the LOCA transient do not exceed design values. As part of criterion 1),

initial pool temperatures are low enough to preclude steam bypass through the suppression pool and into the containment airspace during ,

a LOCA.  !

A set of four initial pool temperatures were developed. These were based on the following considerations:

1. Containment Pressure and Temperature Design Limits

2. Complete Condensation

3. LOCA Condensation Oscillation (CO) Loads

4. LOCA Chugging Loads 1596C E2-2 8/14/87 SL-3040

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ENCLOSURE 2 (Continued)

SAFETY EVALUATION SUPPRESSION POOL TEMPERATURE LIMIT l

3,1 Pressure and Temperature Design Limits The pressure and temperature design limits for several Mark I plants (including Plant Hatch) were compared to the maximum predicted containment pressures and temperatures during a LOCA. Due to the very high containment temperature and pressure design limits given for Mark I containments, there was a large margin noted between predicted and design values and large increases in the operational pool temperature limit would be acceptable.

Based on pressure and temperature design limit considerations alone, j an operational pool temperature of 133-1610F (dependant on Plant Configuration) was established as acceptable. Plant Hatch would operate below this maximum pool temperature range and is. thus acceptable.

3.2 Complete Condensation i

Test data from the Mark I Full Scale Test Facility (FSTF) tests were '

analyzed to determine the maximum tested pool temperatures (and minimum subcooling conditions) for which complete steam condensation was confirmed. Based on these analyses, a range in maximum pool temperatures of 190-2000F was obtained. The maximum operational pool temperature was determined by comparing these temperatures to the maximum predicted pool temperatures during a LOCA. The resultant temperature margins were added to the current operational temperature limits. -)

i To assure complete condensation, an operational pool temperature j range of 118-1330F was determined to be acceptable. Plant Hatch I would operate below this maximum pool temperature range and is thus l acceptable.

3.3 Condensation Oscillation Loads The current Mark I C0 load definition (NE00-21888) is based on C0 pool boundary pressures measured during ' the Mark I FSTF test (NEDE l 24539). C0 loads are largely affected by the pool temperature and by 1 the enthalpy flux though the downcomer vents. A proprietary l correlation which considered these two parameters was developed by l General Electric to predict C0 loads based on transient conditions. l 1596C E2-3 8/14/87 SL-3040 1

ENCLOSURE 2 (Continued)

SAFETY EVALUATION SUPPRESSION POOL TEMPERATURE LIMIT This correlation was used to predict the C0 loads for the expected l LOCA conditions in representative Mark I plants. The correlation was -

also used to predict-the C0 load for the conditions simulated during the FSTF tests. A comparison of the plant specific predictions with the FSTF predictions was used to determine the _ margin between expected and design C0 loads and subsequently the associated margin in pool temperature.

i As a result of the above analysis, initial pool temperatures in the range of 110-1500F were determined to be acceptable based on C0 load considerations, alone. Plant Hatch falls within this pool

. temperature range.

3.4 Chugging Loads A review of chugging data obtained during the Mark I FSTF tests.(NEDE 24539-P) indicated that there is a high pool temperature threshold for chugging of 1350F, above which chugging does not occur.

Consequently, there is - no impact on chugging- loads resulting from raised pool temperatures, i

1596C E2-4 8/14/87 SL-3040

1-I ENCLOSURE 3 PLANT HATCH - UNITS 1, 2 '"

NRC DOCKETS 50-321, 50-366 OPERATING LICENSES DPR-57,-NPF-5 REOUEST TO REVISE TECHNICAL SPECIFICATIONS:

SUPPRESSION P0OL TEMPERATURE LIMIT .

10 CFR 50.92 EVALUATION  !

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PROPOSED CHANGES:

The proposed changes would modify Unit 1 Technical Specification.

3.7. A.1.c to change the operational suppression pool water temperature limit during periods of high river temperature. Similarly, the Unit 2 Limiting Condition for Operation Specification 3.6.2.1.b and the  ;

resulting Action statement would be modified to raise suppression pool operating temperature limits during periods of high river temperature.

Basis for Proposed Chanael:

Please refer to Enclosures i and 2 for a detailed description of the safety basis for the proposed changes. Based on these Enclosures, the following conclusions-can be drawn:

These changes do not involve a significant increase in the probability or consequences of an accident, because applicable accident analyses which could be impacted by raising the suppression pool operating limit ' have  ;

been examined in Enclosure 1 and found to be acceptable. The scram'and '

depressurization limits are unchanged.

The possibility of a different kind of accident from any analyzed '

previously is not created by these changes, since the proposed changes would only revise an operating limit on permissible pool temperature. i This change does not involve the potential for a new accident type since plant design and function are unchanged.

1 Margins of safety are not significantly reduced by these changes, because the impact of the proposed pool temperature has been evaluated relative

~ to safety analyses (Enclosure 2) and margins have been shown to be insignificant 1y impacted. Sufficient heat capacity remains in the suppression pool for complete condensation of decay and sensible heat  !

following an accident or reactor shutdown. j l

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