ML20209B672

Submits Addl Info for 860825 Application to Amend Tech Specs Re RWCU Leakage Detection Sys.Nrc Requests & Util Responses Listed.Ge Responding to Item 6.A.1 of Ref Ltr & Viewgraphs Showing Leakage Detection Response Times Encl

ML20209B672
Person / Time
Site:	Hatch
Issue date:	01/23/1987
From:	Gucwa L GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
RTR-REGGD-01.105, RTR-REGGD-1.105 1018C, SL-1798, TAC-62757, TAC-62758, NUDOCS 8702040096
Download: ML20209B672 (8)

Text

Georgia Fbwer Company

.' , 333 Ptedmont Avenue Atlanta, Georgia 30308 Telephone 404 52&6526 Maihng Address:

Ibst Office Box 4545 Atlanta, Georgia 30302 Georgia Power L. L Gucwa *- it>c souttun ettcinc sytem Manager Nuclear Safety 3(_]79g and Licensing January 23, 1987 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555 NRC DOCKETS 50-321, 50-366 OPERATING LICENSES DPR-57, NPF-5 EDWIN I. HATCH NUCLEAR PLANT UNITS 1 AND 2 PROPOSED CHANGES TO TECHNICAL SPECIFICATIONS CHANGES TO RWCU LEAKAGE DETECTION SYSTE!1 ADDITIONAL INFORMATION Gentlemen:

Georgia Power Company's (GPC) submittal of August 25, 1986, proposed new setpoints for instruments which provide isolation of the Plant Hatch Units 1 and 2 Reactor Water Cleanup (RWCU) systems upon detection of high temperature in the respective RWCU rooms. This letter provides additional information in support of that change request, and is submitted pursuant to a verbal NRC staff request.

NRC information requests and GPC responses are as follows:

NRC Request: Provide additional information in regard to GPC's statement, in Enclosure 1 of the letter of August 25, 1986, that " General Electric has provided documentation which shows that the plant is designed to withstand a break of the largest pipe in the RWCU system, resulting in an inventory loss of 6624 gallons prior to system i sol ation. " Provide a copy of the GE documentation.

GPC Response: The bounding value for inventory loss from a postulated break of the largest pipe in the RWCU system is provided in Table N.5-1 of the Unit 1 FSAR and Table 15A-2 of the Unit 2 FSAR. The blowdown from a rupture of the piping, per the FSARs, is a constant 1448 lb/sec for 43 seconds. Isolation for this break is accomplished by the RWCU high differential flow instrumentation. This is equivalent to 7466 gallons of water at standard temperature and pressure. The actual high energy line break calculation supports this value.

The GE analysis referenced provides that the RWCU rooms can experience a 5 GPM break for up to 22.08 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> without affecting plant safety from an inventory basis, which equals 6624 gallons total and is conservative with 4

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Georgia Power 1 U. S. Nuclear Regulatory Commission January 23, 1987 Page Two respect to the above analyses. This information is documented in a July 27, 1983 letter from GE to GPC which is enclosed. The applicable GE Design Specification provides that the RWCU system shall isolate when unidentifiable leakage exceeds 25 gpm. Calculations show that the proposed analytical limit of 1570F will result, for a 25 gpm break, in }

isolation in 1393 seconds, with a corresponding inventory loss of less 3 than 600 gallons. This is very conservative with respect to the j' inventory loss limits described above.

NRC Request: Does the proposed analytical limit of 1570 refer to a uniform room temperature or localized temperatures in the area of the equipment.

{

GPC Response: The 1570 temperature is considered to be a uniform (

temperature throughout the rooms. However, there are two sensors mounted -

at different locations in each of these rooms per unit (six sensors per unit total), each able individually to initiate closure of the isolation valves. In addition, these are small rooms so that two temperature elements per room are considered to be adequate coverage.

NRC Request: The proposed change involves a reduction of margin. For the purpose of significant hazards considerations (Enclosure 2 to GPC's letter of August 25, 1986), provide additional details on the proposed margin reduction.

GPC Response: As stated in our letter of August 25, 1986, the limiting factor in determination of the new setpoint is consideration of environmental qualification requirements for safety related equipment in the RWCU rooms.

There are three RWCU rooms, the RWCU pump room, the RWCU phase separator room, and the RWCU heat exchanger room. Pursuant to regulatory requirements, environmental qualification (temperature versus time) curves have been developed for each of these rooms based on the limiting pipe break for each room. In order to ensure that the proposed limit is acceptable from the standpoint of equipment qualification, it is necessary to show that the temperature versus time curves for the 25 gpm design specified detectable leakage are bounded by the curves for the full pipe break.

The curves for environmental qualification for these rooms show that the leakage detection curves are enveloped if it is assumed that the room temperature decay after isolation occurs on the same slope as that of the 1018C 100779

Georgia Power A U. -S. Nuclear Regulatory Commission January 23, 1987 Page ihree full break environmental qualification curves. This assumption is conservative since the full environmental qualification break puts more energy into the room. Also, since the temperature profile begins at a i;wer value, the heat sinks in the room have not ' absorbed as much energy. Hence, the decay slopes of the 25 gpm leakage curve should be steeper after isolation. Saturated steam conditions exist in these rooms.

Time modified curves were generated to calculate the environmental qualification impact of the leakage detection system isolation. Time modified curves are necessary since the original leakage detection curves were generated at an initial condition of 800F (to identify the minimum temperature leakage detection break) and the initial conditions of the full break calculations were 1050F (to maximize temperatures). The time modified curves were generated by shifting the existing leakage detection curves to the left (resulting in higher temperature values for a given time) until the point of the curve equaled 1050F at time equals O seconds. This method was evaluated ' and found to be representative since the initial energy in a room at either 800F or 1050F is insignificant compared to the amount of energy released during the 25 gpa leak period.

Figures 1, 2 and 3 (enclosed) show the full break, 25 gpm leak, and 25 gpm leak time modified curves for each of the three RWCU rooms for Plant Hatch Unit 2. These same curves are used for Unit 1. The RWCU heat exchanger room is the limiting case since the leakage curve intersects the full break curve at the lowest temperature. Thus, this room is used as the basis for calculating the analytical limit for the proposed isolation setpoint. Actual data points from the High Energy Line Break calculation for this room were plotted. This is shown in Figure 1. The unshifted curve is used to provide the temperature at the time value determined by the intersection of the full break curve (based on the HELB calculation) and the shifted ' curve. This temperature is 1570F, which is the analytical limit from which the proposed allowable value is derived.

This analytical limit results in a total isolation time, including valve closing time and signal delay time, of 1393 seconds, and a corresponding inventory loss of less than 600 gallons, as previously stated.

Regulatory Guide 1.105 is used for determination of the appropriate Technical Specification allowable value based on the above analytical limit. Application of this methodology results in an allowable value of L 1510E. The allowable value proposed is conservatively reduced to 1500t.

I

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l 1018C

• 775 . . _ _ _ , _ _ _ _ _ _ - _ _ . . _ _ _ _ _ _ _ . _ -_- -_ _ ___.

Geor!;ia Power A U. S. Nuclear Regulatory Commission January 23, 1987 Page Four Based on the above, Georgia Power believes that appropriate margins are preserved with the proposed limit, and that the setpoint change should not be deemed significant. Inventory loss margins are insignificant 1y affected. Equipment qualification specifications ve maintained at appropriate levels based on conservative assumptions as detailed above.

As a point of clarification, in addition to the RWCU isolation instrumentation, other equipment requiring environmental qualification exists in the RWCU rooms. On Unit 1, these rooms house the Core Spray system inboard and outboard discharge valves. On Unit 2, the RWCU rooms house these same valves as well as the Containment Spray inboard and outboard discharge valves. The above analysis considers the environmental qualification requirements of all this equipment, which is in fact qualified to harsher conditions than would exist in the RWCU rooms.

If you have any questions in this regard, please contact this office at any time.

Sincerely, W4 - -

L. T. Gucwa REB /lc Enclosures c: Georgia Power Company U. S. Nuclear Regulatory Commission Mr. J. P. O'Reilly Dr. J. N. Grace, Regional Administrator Mr. J. T. Beckham, Jr. Mr. P. Holmes-Ray, Senior Resident Mr. H. C. Nix, Jr. Inspector - Hatch GO-NORMS Mr. G. Rivenbark, Licensing Project Manager - Hatch 1018C 700775

ENCLOSURE GENERAL 0 ELECTRIC i 1

APPAAATUs ANo ENGNLERING SERVICES e SOUTHERN SEIMCE DEPARTMENT GENERAL ELECTRIC COMPANY # P O BOX 105064 9 ATLANTA. GEORGA 30348 cc: Georgia Power Company E. F. Cobb L. T. Gucwa J. R. Jordan G-GPC-3-255 ou e Company Services, Inc.

W. F. Garner July 27,1983 G$nera ectric Company P. F. MacDonald Mr. M. D. Faulkenberry R. T. Schellinger Georgia Power Company is h.C.

h Floor Bc - ithersburg 33 B1 g , 1 p ],,

Atlanta, GA 30302

Subject:

Hatch 1 & 2 ATS/ June 22, 1983 Meeting Response

Reference:

Southern Company Services Letter LSH-NS-1812 dated June 27,1983

Dear Mr. Faulkenberry:

As comitted during the June 22, 1983 Analog Transmitter Trip System meeting at Plant Hatch, General Electric can provide the following response to item 6.A.1 of the reference: Leakage detection response times following a specified line break are:

System Time Limit for Detecting a SGPM Leak Main Steam 89934 min (1498.9 hr)

HPCI 26688 min (444.8 hr)

RCIC 2535 min (42.25 hr)

RWCU 1325 min (22.08 hr)

Very truly yours, W /A M. L. Hurstell, Jr.

Service Supervisor - Nuclear Southeastern Region MLH:RPD:ta

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FIGURE 1

)

HNP-2 COMPARTMENT TEMPERATURE ANALYSIS RWCU HEAT EXCHANGER ROOM 225 FULL BREAK j

200 - \\ TIME MODIFIED 1

^

CURVE J u. 175-

) L ACTUAL I

E CURVE g 150 - (25 gpm leak) l i < / ACTUAL DATA POINTS i

@ 125-

-l g FROM CALCULATION l  !" /

100 -

l 75-1 l

l 50 , , i i i i i i i l 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 TIME (SECONDS)

i l

l FIGURE 2 j HNP-2 COMPARTMENT TEMPERATURE ANALYSIS i RWCU RECIRCULATION PUMP ROOM l 225 i TIME MODIFIED

! CURVE i 200 -

1 j

l ACTUAL

! ^ 175- CURVE 1

l 7 (25 gpm leak)

A lLi

$ 150-i Q

m j g 125-1 lE FULL BREAK 75-l 50 i i i i i i i i i

! O 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 t

TIME (SECONDS) l ,

I l

I .

i l

,l FIGURE 3 HNP-2 COMPARTMENT TEMPERATURE ANALYSIS RWCU PHASE SEPARATOR ROOM 220 l

t

! 2M -

l TIME MODIFIED -

i CURVE J 180 -

l l 7 ACTUAL

) CURVE

E 160 - (25 gpm leak) 1-- g i <

g 140 -

n.

.1 2 FULL BREAK I N 120 -

l 100 -

)

80 i i i i i i i i

, 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 TIME (SECONDS) i l

l

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