Information Notice 1988-23, Potential for Gas Binding of High-Pressure Safety Injection Pumps During a Loss-Of-Coolant Accident

Potential for Gas Binding of High-Pressure Safety Injection Pumps During a Loss-Of-Coolant Accident

ML031150208
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	05/12/1988
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-88-023, NUDOCS 8805060246
Download: ML031150208 (10)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 May 12, 1988 NRC INFORMATION NOTICE NO. 88-23: POTENTIAL FOR GAS BINDING OF HIGH-PRESSURE

SAFETY INJECTION PUMPS DURING A LOSS-OF-

COOLANT ACCIDENT

Addressees

All holders of operating licenses or construction permits for pressurized-water

reactors.

Purpose

The purpose of this Information notice is to alert addressees to potential

problems resulting from hydrogen transport from the volume control tank and

accumulation in emergency core cooling system piping. It is expected that

recipients will review the information for applicability to their facilities

and consider actions, as appropriate, to avoid similar problems. However, suggestions contained in this information notice do not constitute NRC

requirements; therefore, no specific action or written response is required.

Description of Circumstances

On February 26, 1988, the licensee was operating Farley 1 at power near the end

of the current fuel cycle. Valves 8706A and B (see Figure 1) had been stroked

as required for surveillance testing. After testing was completed, the licensee

noted that the boron concentration in the reactor coolant system was higher than

expected and suspected that there was leakage through one of these valves. To

determine whether valve 8706A was seated, the licensee took a coolant sample

from a vent downstream from the valve in order to analyze the sample for boron

concentration. Fifty cubic feet of gas was vented from the line before a coolant

sample could be obtained. The gas was 98 percent hydrogen.

Discussion:

Farley 1 has three centrifugal charging pumps and two centrifugal residual heat

removal (RHR) pumps. During a loss-of-coolant accident (LOCA), the charging

pumps function as high-pressure safety injection (HPSI) pumps, and the RHR pumps

function as low-pressure safety injection (LPSI) pumps. When a safety injection

signal is generated, the discharge sides of the HPSI and LPSI pumps are aligned

to supply coolant to the cold legs of the reactor coolant system, the suction

sides of the HPSI and LPSI pumps are aligned to the refueling water storage tank

(RWST), and the pumps are started. At the low water level setpoint for the RWST

88O5O6O246 ZA

IN 88-23 May 12, 1988 when transferring to the recirculation mode, the suction sides of the LPSI pumps

are realigned from the RWST to the sump. At the same time, the discharge sides

of the LPSI pumps are aligned to supply coolant to the suction header for the

HPSI pumps as well as the cold legs of the reactor coolant system. In addition, the two block valves in the HPSI suction header between HPSI pumps B and C close

to establish independent trains.

Had a small-break LOCA occurred before the line downstream of valve 8706A was

vented, 50 cubic feet of hydrogen would have been swept through HPSI pumps A

and B when valve 8706A opened. The licensee stated that if 6 cubic feet of

hydrogen were swept through one HPSI pump as a single gas bubble, the pump

might be damaged significantly. Whether or not hydrogen gas causes significant

damage to HPSi pumps A and B depends on the amount of mixing of hydrogen and

water before the mixture enters the pumps and on the distribution of hydrogen

bubbles between HPSI pumps A and B. Because of this uncertainty, the oper- ability of HPSI pumps A and B would be in question with hydrogen trapped in

lines upstream of the pumps.

Figure 1 shows the layout for piping and components on the suction side of the

HPSI pumps for Units 1 and 2. For Unit 1, to provide physical separation of

the lines from the LPSI pumps to the suction header for the HPSI pumps, the

architect-engineer routed the line containing valve 8706A so that part of the

line is 32 feet above the line from the volume control tank (VCT). Figure 2 shows the elevations of horizontal piping on the suction side of the HPSI pumps.

The lines for Unit 2 were arranged in a similar way.

Hydrogen is normally used for the cover gas in the VCT; thus, water flowing

through the VCT is saturated with hydrogen while it is in the VCT. If the

local pressure in the piping at some point between the VCT and HPSI pump

suction nozzles is less than VCT pressure, the dissolved hydrogen will come

out of solution and will not immediately go back into solution even if the

pressure downstream from that point is greater than VCT pressure. The licensee

believes that the pressure distribution in some elbows and tees downstream from

the VCT is such that some hydrogen comes out of solution in those fittings and

that these hydrogen bubbles are swept through the pumps without damaging them.

In the suction piping of pump A, however, some of the bubbles are trapped in the

vertical section of line that runs to the high point vent. Data obtained by the

licensee indicate that the collection rate is approximately 5 cubic feet per day.

At Unit 2, there is a second hydrogen collection point In the suction piping

for HPSI pump B (see Figure 3). With pump R out of service, hydrogen gas

collects between the tee and the closed valve.

The licensee has taken interim corrective action to avoid declaring FPSI pump

A in Unit 1 and HPSI pumps A and B in Unit 2 inoperable. In Units l and 2, the line downstream from valves 8706A is vented once each shift to remove

accumulated hydrogen gas. In Unit 2, only pump B is normally operated so

that hydrogen gas bubbles are swept throuoh the pump and cannot accumulate.

IN 88-23 May 12, 1988 No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact the technical

contact listed below or the Regional Administrator of the appropriate regional

office.

etaV o

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Roger Woodruff, NRR

(301) 492-1180

Attachments:

1. Figure 1 - Farley 1 & 2 Charging Pump Schematic

2. Figure 2 - Farley 1 Horizontal Piping Elevations

3. Figure 3 - Farley 2 Horizontal Piping Elevations

4. List of Recently Issued NRC Information Notices

Attachment 1 VENT

RHR ( LPSI) PUMP

8706A

LETD( )WN

RWST

C a VCT

CHARGING (HPSI)

PUMPS

RHR ( LPS I PUMP

8706e

FIGURE 1 - FARLEY 1 & 2 CHARGING PUMP SCHEMATIC

- 140 FT

"I - 130 FT

- 120 FT

!

-- - 110 FT

RWST

- o00 FT

CHARGING (IHPSI)

PULP A

90 FT

-

(

RHR CLPSI) PUmP

8700A

-0o FT

0

FIGURE 2 - FARLEY 1 HORIZONTAL PIPING ELEVATIONS S

CD

(-I.

0 , 1.

- 110 FT

RCS VCT

CHARGING (HPSI)

- 100 FT PUMPS A & C

CHARGING (HPSI)

PUMP B

- 90 FT

FIGURE 3 - FARLEY 2 HORIZONTAL PIPING ELEVATIONS

0

F

(D

a

w

I_'

Attachment 4 IN 88-23 May 1? 1988 Page I of I

LIST OF RECENTLY iSSUED

NRC INFOWATION NOTICES

fLi Wf

. , _ .D

• fl U Late CT

Notice No. SubJlect Issuance Issued to

8&22 Disposal of Sludge from 5/12/88 All holders of OLs

Onsite Sewage Treatment or CPs for nuclear

Facilities at Nuclear power reactors.

Power Stations

88-21 Inadvertent Criticality F/9/88 All holders of OLs

Events at Oskarshamn or CPs for nuclear

and at P.S. Nuclear power reactors.

Power Plants

88-2C Unauthorized Individuals S/5/88 All holders of OLs

Man1pulating Controls and or CPs for nuclear

Performing Control Room power. test and

Activities research reactors.

and all licensed

operators.

88-19 Questionable Certification 4/26/88 All holders of OLs

of Class IE Components or CPs for nuclear

power reactors.

8a-l8 malfunction of Lockbox on 4/25/88 All NRClicensees

Radiography Device authorized to

manufacture, distribute, and/or operate radio- graphic exposure

devices.

.8-17 Suemery of Responses to NRC 4/22/88 All holders of OLs

Bulletin 87-01, Thinning of or CPs for nuclear

Pipe Walls In Nuclear Power power reactors.

Plants'

88-16 Identifying Waste Generators 4/27/88 Radioactive waste

in Shipments of Low-Level collection and

Waste to Land Disposal service company

Facilities licensees handlina

prepackaged waste, and licensees operating

low-level waste

disposal facilities.

OL

• Operating License

CP* Construction Permit

UNITED STATES FIRST CLASS MAIL

POSTAGE S FEES PAID

NUCLEAR REGULATORY COMMISSION USNRC

WASHINGTON, D.C. 20555 PERMIT No. 0-E7 OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE, $300

IN 88-23 May 12, 1988 No specific action or written response Is required by this information notice.

If you have any questions about this matter, please contact the technical

contact listed below or the Regional Administrator of the appropriate regional

office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Roger Woodruff, NRR

(301) 492-1180

Attachments:

1. Figure 1 - Farley 1 & 2 Charging Pump Schematic

2. Figure 2 - Farley 1 Horizontal Piping Elevations

3. Figure 3 - Farley 2 Horizontal Piping Elevations

4. List of Recently Issued NRC Information Notices

• See previous concurrence

EAB:NRR* EAB:NRR* TECH: ED* C:EAB:NRR* >GCB RR

RWoodruff: RLobel MMejac WLanning CH llinger

4/29/88 4/29/88 5/4/88 4/29/88 5/ 5/&/88

IN 88-XX

May , 1988 No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact the technical

contact listed below or the Regional Administrator of the appropriate regional

office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Roger Woodruff, NRR

(301) 492-1180

Attachments:

1. Figure 1- Farley 1 & 2 Charging Pump Schematic

2. Figure 2- Farley 1 Horizontal Piping Elevations

3. Figure 3- Farley 2 Horizontal Piping Elevations

4. List of Recently Issued Information Notices

• See previous concurrence

EAB:NRR* EAB:NRR* TECH:ED . C:EAB:NRI* C: GCB: NRR D:DOEA:NRR

RWoodruff: MLobel MeahA eWIanning CHBerlinger CERossi

/ /88 / /88 r/f /88 / /88 / /88 / /88

IN 88-XX

April , 1988 No specific action or written response is required by this information notice.

If you have any questions about this matter, please contact the technical

contact listed below or the Regional Administrator of the appropriate regional

office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Roger Woodruff, NRR

(301) 492-1180

Attachments:

1. Figure 1- Farley 1 & 2 Charging Pump Schematic

2. Figure 2- Farley 1 Horizontal Piping Elevations

3. Figure 3- Farley 2 Horizontal Piping Elevations

4. List of Recently Issued Information Notices

EAB:NRR EAB:NRR TECH:ED C:GCB: NRR D:DOEA:NRR

BWoodruff: RLobel MMear CHBerlinger CERossi

4 /-j'/88 4-/>/88 / /88 /f88 / /88 / /88