L-88-103, Forwards Response to Generic Ltr 87-12,Item 5, Loss of RHR While RCS Partially Filled & Omitted from Original Submittal on 870910

Forwards Response to Generic Ltr 87-12,Item 5, Loss of RHR While RCS Partially Filled & Omitted from Original Submittal on 870910

ML17221A654
Person / Time
Site:	Saint Lucie
Issue date:	02/29/1988
From:	Conway W FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
GL-87-12, L-88-103, NUDOCS 8803070002
Download: ML17221A654 (9)

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ACCEL7MVED DISHDBUYION DEMONSTRATI 8 SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:8803070002 DOC.DATE: 88/02/29 NOTARIZED: YES FACIL:50-335 St". Lucie Plant, Unit 1, Florida Power

& Light Co.

50-389 St. Lucie Plant, Unit 2, Florida Power

& Light Co.

AUTH.NAME AUTHOR AFFILIATION CONWAY,W.F.

Florida Power

& Light Co.

RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

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DOCKET 05000335 05000389

SUBJECT:

Forwards response to Generic Ltr 87-12, "Loss of RHR While RCS Partially Filled."

DISTRIBUTION CODE:

A061D COPIES RECEIVED:LTR L

ENCL SIZE: 5 TITLE: OR/Licensing Submittal:

Loss of ResiduaT Heat Removal (RHR) GL-87-12 NOTES:

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P. O. BOX 0, JUNO BEACH, FL 33408-0420

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FEBRUARY. 2 9

$988 L-88-103 U. S. Nuclear Regulatory Commission Attn:

Document Control Desk Washington, D.C.

20555 Gentlemen:

Re:

St. Lucie Units 1 and 2

Docket Nos.

50-335 and 50-389 Generic Letter 87-12 "Loss of Residual Heat Removal (RHR)

While the Reactor Coolant System RCS is Partiall Filled" By letter L-87-390, dated September 10,

1987, Florida Power Light Company (FPL) responded to all aspects of the subject generic letter with the exception of Item 5.

The NRC Staff had previously agreed with FPL's phased response for this item of the generic letter.

Attached is FPL's response to Item 5

for St.

Lucie Units 1 and 2.

This completes FPL's response to this generic letter.

This information is provided pursuant to 10 CFR 50.54(f).

If additional information is required, please contact us.

truly yours, W.

Conway ior Vice President Nuclear WFC/EJW/dh Attachment cc:

Dr.

J.

Nelson

Grace, Regional Administrator, Region II, USNRC Senior Resident Inspector, USNRC, St. Lucie Plant EJW23.GL 8803070002 880225'DR ADOCK 05000335 P

DCD an FPL Group company

STATE OF FLORIDA

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ss.

COUNTY OF PALM BEACH )

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That he is Vice President Nuclear Ener of Florida Power & Light Company, the Licensee herein; That he has executed the foregoing document; that the statements made in this document are true and correct to the best of his knowledge, information, and

belief, and that he is authorized to execute the document on behalf of said Licensee.

. W. Dic ey Subscribed and sworn to before me this ay of

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- '"NOTA'RV;P

'.'fPaltii>Beach, IC, in and for the County State of Florida My Commission expires:

ROTARY PUBLIC STATE OT fLOB iDX HY COHHISSIOH EXP JULY 30,1BBU SORDED THRU GERERAL IRS. UlfD,

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RESPONSE

TO NRC GENERIC LETTER 87-12 ITEM ¹5 RE:

1.

2.

3.

Florida Power 5 Light's Response to NRC Generic Letter 87-12, FPL Letter No. L-87-390 dated September 18, 1987 NUREG-1269, "Loss of Residual Heat Removal System",

Diablo Canyon

-Unit 2, April 10, 1987.

"Loss of RHR Scenarios

- Detailed gualitative Assessment

- Final

Report, October 21, 1987",

Prepared for the Combustion Engineering Owner's

Group, Combustion Engineering Report No.

CE-NPSD-421 Per reference 1, Florida Power

& Light responded to Items 1-4 and 6-9 of the Nuclear Regulatory Commission Generic Letter 87-12.

The following is the response to Item ¹5.

ITEM ¹5:

Reference to and a

summary description of procedures in the control room of your plant which describe operation while the RCS is partially filled. Your response should include the analytic basis you used for procedures development.

We are particularly interested in your treatment of draindown to the condition where the RCS is partially filled, treatment of minor variations from expected behavior such as caused by air entrainment and de-entrainment, treatment of boiling in the core with and without RCS pressure boundary integrity, level difference in the RCS and the effect upon instrumentation indications, treatment of air in the RCS/RHR

system, including the impact of air upon NSSS and instrumentation

response, treatment of vortexing at the connection of the RHR suction(s) to the RCS.

Explain how your analytic basis supports the following as pertaining to your facility: (a) procedural guidance pertinent to the timing of operations, required instrumentation,

cautions, and critical parameters; (b) operations control and communications requirements regarding operations that may perturb the

NSSS, including restrictions upon testing, maintenance, and coordination of operations that could upset the condition of the NSSS; and (c) response to loss of

RHR, including regaining control of RCS heat

removal, operations involving the NSSS if RHR cannot be restored, control of effluent from the containment if containment was not in an isolated condition at the time of loss of RHR, and operations to provide containment isolation if containment was not isolated at the time of loss of RHR (guidance pertinent to timing of operations, cautions and warnings, critical parameters, and notifications is to be clearly described).

RESPONSE

"Draining of The Reactor Coolant System" is delineated in Operating Procedure No.'s 1-0120021 and 2-0120021, respectively for Units 1

5 2.

Pertinent precautions delineated in the these procedures are:

'a ~

b.

C.

Drain the reactor coolant system (RCS) at a rate less than 500 gpm (to enable the quench tank nitrogen regulator to maintain positive pressure on the system via the open Power Operated Relief Valves).

Do not allow reactor coolant system level to decrease below the hot leg centerline during shutdown cooling oper ation (to preclude vortexing at the shutdown cooling (SDC) connections to the RCS).

Prior to draining, both shutdown cooling systems shall be operable with one in operation.

The initial condition of the RCS prior to the commencement of draining of the RCS is Cold Shutdown with two operable shutdown cooling loops, one SDC loop in-service.

The system is solid with pressure maintained less than or equal to 200 psia using charging and letdown. All high pressure safety injection pumps and one charging pump have been "racked out".

Shutdown Cooling flow is maintained at 3000 gpm or greater.

In preparation of draining the

RCS, a

tygon level indicator is connected between a

reactor coolant pump (RCP) suction leg and a pressurizer vent.

A walkdown of the tygon tubing is performed to verify that it is clear of kinks.

Once installed, communication is established between the operator at the tygon level indicator, personnel in the control room and personnel in the reactor auxiliary building.

In addition, Unit 2

has permanently installed refueling level indication, both wide range (0-720 inches of water) and narrow range (0-48 inches of water),

which is monitored.

These level transmitters are installed between the 2A Hot Leg and a pressurizer vent.

A permanent level system is to be installed on Unit 1

during the upcoming Summer 1988 refueling outage.

Therefore, St.

Lucie has or will have independent RCS level indication that is monitored during RCS draining and while at mid-nozzle level.

The RCS is drained to either the Refueling Water Tank (RWT) or the Waste Holdup Tanks.

Pressurizer level indication is monitor ed along with the tygon tube refueling level indicator during this draining.

Extreme caution is used during draining operations at these low levels to prevent loss of SDC heat removal.

"SDC/LPSI

- Off Normal Operation",

Procedure No.'s.

1-0440030 and 2-0440030 for Units 1

8 2, respectively, specify the actions to be taken in the event of variations from expected behavior.

Parameters monitored for indication of loss of shutdown cooling capacity are SDC low flow, SDC heat exchanger outlet temperature, low pressure safety injection (LPSI) pump discharge

pressure, SDC high pressure and alarms associated with valve failure.

These procedures stipulate the actions that must be taken if there i,s a loss of SDC due to low RCS level or excessive RCS heat-up. If a LPSI/SDC pump is lost, the standby LPSI is not started until the reason for losing the running pump is determined. If air binding of the LPSI is suspected, the LPSI is returned to service by aligning the pump suction to the refueling water tank and diverting the LPSI pump discharge through the SDC warmup valves.

The pump is started and stopped, as necessary, to clear the pump suction of air. Suction and, discharge is slowly realigned to the RCS.

If a plant cooldown is in progress and shutdown cooling cannot be restored, the shutdown cooling system is isolated.

If the RCS is

solid, natural circulation is relied on to provide core cooling. If a pressurizer bubble is

1

still established, the pressure is increased to the minimum pressure for

, running the reactor coolant pumps and at least one RCP is started.

Auxiliary feedwater flow is established to each steam generator and cooldown re-established using the Atmospheric Steam Dump valves.

If refueling operations are in progress and shutdown cooling cannot be

restored, refueling operations are stopped and containment integrity is ensured.

The fuel pool cooling system is aligned and operated until shutdown cooling can be restored.

The analytical bases for procedure development is based upon the following:

1.

The procedures were developed based upon criteria provided in the Plant Technical Specifications and the Final Safety Analysis Report.

In

addition, the available Net Positive Suction Head margin for operation at RCS mid-nozzle level was conservatively calculated to be 22 and 5

feet, respectively, for Units 1 L 2.

Based upon the above, operation at mid-nozzle is an acceptable mode of operation.

Precautions delineated in plant procedures do not permit draining the RCS level below this level. It must be noted that St.

Lucie has not had a sustained loss of RHR event since 1978.

2.

The basis of the St.

Lucie procedures is the prevention of loss of shutdown cooling.

In order to ensure that SDC is not lost due to a loss of LPSI pump

suction, reliable RCS level is required.

Permanent refueling level indication, with wide and narrow range indication, has been installed on St.

Lucie -

2 and is to be installed on St. Lucie -

1 during the Summer 1988 refueling outage.

The level indicators have a

measurement leg off the 2A hot leg and the reference leg is connected to a pressurizer vent.

Therefore, the critical level parameter (i.e.

the level in the hot legs) for control of the RHR system is the level being monitored.

In addition, the installation of the system at St.

Lucie Unit 2 was performed under the St.

Lucie Design Control program.

The Construction and guality Control processes are dictated by the Backfit Administrative Site Procedures to assure proper installation.

Florida Power

& Light is currently involved in a

Combustion Engineering Owner's Group (CEOG) effort to assess the loss of RHR scenarios as identified by reference 2.

A detailed qualitative assessment (reference 3) has been prepared by Combustion Engineering for the CEOG for the unanalyzed conditions of unexpected RCS pressurization and loss of RCS inventory.

Florida Power

5. Light (along with other participating CEOG members) has authorized Combustion Engineering to continue the assessment of the loss of RHR scenario by reviewing existing plant procedures and recommending enhancements.

In addition, the Combustion Engineering Owner's Group has requested a

proposal from Combustion Engineering to evaluate vortexing at the RHR connection to the RCS system.

Based upon the above, plant procedures will be revised as deemed appropriate.

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