Information Notice 1987-57, Loss of Emergency Boration Capability Due to Nitrogen Gas Intrusion

Loss of Emergency Boration Capability Due to Nitrogen Gas Intrusion

ML031130493
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:	11/06/1987
From:	Rossi C Office of Nuclear Reactor Regulation
To:
References
IN-87-057, NUDOCS 8711020017
Download: ML031130493 (8)

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SSINS No.: 6835 IN 87-57 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 November 6, 1987 NRC INFORMATION NOTICE NO. 87-57: LOSS OF EMERGENCY BORATION CAPABILITY

DUE TO NITROGEN GAS INTRUSION

Addressees

power

All holders of operating licenses or construction permits for nuclear

reactors.

Purpose

potentially

This information notice is being provided to alert addressees to systems. The

significant problems resulting from air/gas intrusion into fluid

units with

event described is also an example of fault propagation between information

shared systems. It is expected that recipients will review the

for applicability to their facilities and consider actions, as this appropriate, contained in information

to avoid similar problems. However, suggestions or

no specific action

notice do not constitute NRC requirements; therefore, written response is required.

Description of Circumstances

and Mode

On May 28, 1987, with Turkey Point Units 3 and 4 in Mode 6 (refueling) to both

5 (cold shutdown), respectively, a loss of all boric acid flowpaths

4 boric acid pumps resulting

units occurred. Nitrogen gas entered the Unit boric acid

in these pumps being gasbound and inoperable. At Turkey Point, theconsists of

system (which is part of the chemical, volume and control system)

four boric acid transfer pumps (two per unit) and three boric acid storage to take

tanks. Each unit normally has one boric acid transfer pump alignedthe charging

suction from a boric acid storage tank, injecting boric acid into

aligned

pump suction header. The second boric acid transfer pump is normally The

to circulate boric acid solution through the boric acid storage tanks.

system alignments, including inter- boric acid system design allows for various transfer pump

connecting Units 3 and 4. During this event, a Unit 3 boric acid

service. Loss of the boric acid

and a boric acid storage tank were out of the

system resulted in the licensee being unable to borate or emergency borate margin.

reactor coolant system to ensure maintenance of the required shutdown

trans- Nitrogen entered the boric acid system through a failed Unit 4 boric acid provided

for this seal, the seal is

fer pump mechanical seal. To provide cooling accumulator

an accumulator tank partially filled with demineralized water. The acid

is given a 40-psi nitrogen overpressure to preclude leakage of the boric

71102 7t- iiC

w

a

IN 87-57 November 6, 1987 across the seal faces (i.e., in the event of seal failure, the differential

pressure will ensure that demineralized water flows into the boric acid

The design of this accumulator provided a continuous nitrogen supply fromsystem).

a

3000-gallon liquid nitrogen storage tank, through a 40-psi pressure regulator, and isolation valves that were normally open. Apparently, as demineralized

water entered the boric acid system through the failed seal, additional

was automatically supplied to the accumulator to maintain pressure. The nitrogen

falling

water level then allowed the nitrogen cover gas to enter the boric acid system

through the failed seal.

Based on previous operating experience, the licensee initially assumed that

loss of boric acid flow to Unit 4 was due to plugging of the piping caused the

inadequate heat tracing and boric acid crystallization. While troubleshootingby

efforts were being conducted to locate the source of the boric acid blockage, the Unit 3 boric acid system was cross connected to Unit 4 to provide a tempo- rary boric acid flowpath. This allowed nitrogen gas intrusion into the

Unit 3 boric acid system and gas binding of the available Unit 3 boric acid transfer

pump, resulting in the loss of both normal and emergency boration flowpaths

both units on May 28 and June 3, 1987. to

On June 3, 1987, when the licensee observed that the water level in an accumu- lator for a Unit 4 boric acid transfer pump could not be maintained within

sight glass, the cause of the problem was properly diagnosed as gas binding the

the pumps-as-a-result of i-trogen intrusiont.--The-lieenseer-restored a boric of

- -

acid flowpath by isolating the affected pump and venting the boric acid

system.

One of the root causes of this event appears to be the design of the accumula- tor cover gas system. A continuous supply of nitrogen allowed the uncontrolled

intrusion of nitrogen gas into the Unit 4 boric acid system through the failed

boric acid transfer pump mechanical seal. To preclude recurrence of this, licensee intends to (1) lock closed the nitrogen supply valves to the pump the

water accumulators, and (2) add nitrogen only in a batch method, as requiredseal

maintain seal pressure. The inability of the operators to recognize the to

symptoms of gas binding in fluid systems permitted nitrogen gas intrusion

into the Unit 3 boric acid system when Units 3 and 4 boric acid systems

were

interconnected. In response, the licensee is providing additional operator

training, upgraded procedures, and emphasizing management control of system

configurations and compliance with procedures.

Discussion:

The event described above is intended to be illustrative of the potential

system inoperability resulting from air/gas intrusion. Since 1981, more than for

90 licensee event reports (LERs) have been submitted to the NRC pertaining

events involving air/gas intrusion. The most significant events of those to

reported have involved: (1) the loss of reactor coolant makeup capability,

(2) the loss of essential service water flow, (3) the inoperability of emer- gency diesel generators (loss of cooling flow), (4) the loss of shutdown

cooling, and (5) water hammer. System or component failures resulting from

air/gas intrusion can be significant.

IN 87-57 November 6, 1987 A previous event involving gas intrusion at McGuire Unit 1 is discussed in IE

Information Notice 82-19, "Loss of High Head Safety Injection Emergency

Boration and Reactor Coolant Makeup Capability." Additional events are dis- cussed in IE Information Notice 83-77, "Air/Gas Entrainment Events Resulting in

System Failures." Air/gas intrusion concerns associated with the residual heat

removal system of pressurized water reactors are addressed in Generic Letter 87-12, "Loss of Residual Heat Removal (RHR) While the Reactor Coolant System

(RCS) is Partially Filled."

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

S. D. Stadler, RII

(404)"331-5599 Attachment: List of Recently Issued NRC Information Notices

Attacetnt

IN 87-57 lovevbr 8. 1987 LIST OF RECENTLY ISSUED

INFORYAT101 ItOTICES1987 Iformitlpfl Date of

Kotice lb Subject Issuance Insuvd to

87-56 Improper Hydraulic Control 4/8?7 All helders of OLs

Unit Installation at VA or CPs for boiling

plants. water reactors (CBIRS).

87-SS Pertaele Nbisture/Density 10/28/87 All NHC1icenses

Gauges: Recent Incidents authorized to

of Portable GaugesBeing posse, portable

Stolen or Lost puge.

87-54 Emergency Response Exercises 10/23/7 All holders of L

or CPSfor nuclear

power reactors.

V7-53 Auxiliary F ter Pump 10/20/87 All holders of OLc

Trips Resulting trom Low or CU2for nucleir

Suction Pressure Powr reactors.

87-52 Insulation Breakdo'n of 10/ 7 All holders of DLS

Silicone Rubber-Insulated or Us for nuclear

Single Conductor Cables pow"r reetors.

During High Potential Testing

07-51 Feilure of Low Pressure 10/13/87 All nuclear power

Safety Injection PumpDue reactor fbcilities

to Sael Problems holding en OL or CP.

87-50 Potential LOCAat Migh- 10/1/87 All nuclear power

and Low-Pressure Interfaces reactor facilities

from Fire Damage holding an OL or CP.

07-49 Deficiencies in Outside 108/7 All nucleer power

Containment Flooding reactor facilities

Protection holding en OL or CP.

81-U Informatios Concerning the 10/9/87 All nuclear power

Use of Anaerobic Adhesive/ reactor facilities

Sealants holding an 0L or tP.

OL

• Operating License

CP

• Construction Permit

FIRST CLASS MAIL

UNITED STATES POSTAGE I FEES PAID

NUCLEAR REGULATORY COMMISSION UUSNRC

WASHINGTON, D.C. 20555 PERMIT No G-87 OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE. $300

- . 1t

IN 87-57 November 6, 1987 A previous event involving gas intrusion at McGuire Unit 1 is discussed in IE

Information Notice 82-19, "Loss of High Head Safety Injection Emergency

Boration and Reactor Coolant Makeup Capability." Additional events are dis- cussed in IE Information Notice 83-77, "Air/Gas Entrainment Events Resulting in

System Failures." Air/gas intrusion concerns associated with the residual heat

removal system of pressurized water reactors are addressed in Generic Letter 87-12, "Loss of Residual Heat Removal (RHR) While the Reactor Coolant System

(RCS) is Partially Filled."

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

S. D. Stadler, RII

(404) 331-5599 Attachment: List of Recently Issued NRC Information Notices

• SEE PREVIOUS CONCURRENCES

• C/OGCB:DOEA:NRR

CHBerlinger

1/Z 7 10/23/87

• RI I *OGCB:DOEA:NRR &/SPLB:DEST:NRR SADDEST: NRR *PPMB:ARM

SDStadler JERamsey JCraig AThadani TechEd

10/01/87 10/06/87 10/ /87 10/ /87 10/06/87

IN 87-XX

October xx, 1987 References:

A previous event involving gas intrusion at McGuire Unit 1 is discussed in TE

Information Notice 82-19, "Loss of High Head Safety Injection Emergency

Boration and Reactor Coolant Makeup Capability." Additional events are dis- cussed in IE Information Notice 83-77, "Air/Gas Entrainment Events Resulting in

System Failures." Air/gas intrusion concerns associated with the residual heat

removal system of pressurized water reactors are addressed in Generic Letter 87-12, "Loss of Residual Heat Removal (RHR) While the Reactor Coolant System

(RCS) is Partially Filled."

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

S. D. Stadler, RII

(404) 331-5599 Attachment: List of Recently Issued NRC Information Notices

• SEE PREVIOUS CONCURRENCES

D/DOEA:NRR *C/OGCB:DOEA:NRR

CERossi CHBerlinger

10/ /87 10/23/87

• RII *OGCB:DOEA:NRR CJWPLB DEST:NRR SAD/DEST:N^f *PPMB:ARM

SDStadler JERamsey JCraig AThadan FJI TechEd

10/01/87 10/06/87 10/26/87 10/1&87 10/06/87

I

IN 87-XX

October xx, 1987 References:

A previous event involving gas intrusion at McGuire Unit 1 is discussed in TE

Information Notice 82-19, "Loss of High Head Safety Injection Emergency

Boration and Reactor Coolant Makeup Capability." Additional events are dis- cussed in IE Information Notice 83-77, "Air/Gas Entrainment Events Resulting in

System Failures." Air/gas intrusion concerns associated with the residual heat

removal system of pressurized water reactors are addressed in Generic Letter 87-12, "Loss of Residual Heat Removal (RHR) While the Reactor Coolant System

(RCS) is Partially Filled."

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

Technical Contact:

S. D. Stadler, RII '

(404) 331-5599 Attachment: List of Recently Issued NRC Information Notices

• SEE PREVIOUS CONCURRENCES

• RII *OGCB:DOEA:NRR *PPMB:ARM C/OC: OEA:NRR D/DOEA:NRR

SDStadler JERamsey TechEd CHBerlinger CERossi

10/01/87 10/06/87 10/06/87 10/16/87 10/ /87

IN 87-XX

October xx, 1987 To preclude recurrence of this event, the licensee will (1) lock closed the

nitrogen supply valves to the pump seal water accumulators, and (2) add

nitrogen only in a batch method, as required to maintain seal pressure. The

licensee also is providing additional operator training, upgraded procedures, and emphasizing management control of system configurations and compliance with

procedures.

Discussion:

The event described is Intended to be illustrative. Licensees are cautioned

that the types of system inoperability resulting from air/gas intrusion will

vary. Since 1981, more than 90 licensee event reports (LERs) have been submit- ted to the NRC for events involving air/gas intrusion. The events described

include (1) the loss of reactor coolant makeup capability, (2) the loss of

essential service water flow, (3) the inoperability of emergency diesel genera- tors (loss of cooling flow), (4) the loss of shutdown cooling, and (5) water

hammer. The consequences that can result from such a system or component

failure cannot be overemphasized.

References:

A previous event involving gas intrusion at McGuire Unit 1 is discussed in IE

Information Notice 82-19, "Loss of High Head Safety Injection Emergency

Boration and Reactor Coolant Makeup Capability." Additional events are dis- cussed in IE Information Notice 83-77, "Air/Gas Entrainment Events Resulting in

System Failures." Air/gas intrusion concerns associated with the residual heat

removal system of pressurized water reactors are addressed in Generic Letter 87-12, "Loss of Residual Heat Removal (RHR) While the Reactor Coolant System

(RCS) is Partially Filled."

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

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

Administrator of the appropriate regional office or this office.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

S. D. Stadler, RII

(404) 331-5599 Attachment: List of Recently Issued NRC Information Notices

RII OG i g f NRR PPMB: M C/OGCB:DOEA:NRR D/DOEA:NRR

SDStadler JE sey TechEd. C/ CHBerlinger CERossi

10/1 /87 10/1C/87 10/6 / 7 10/ /87 10/ /87 wnte V.S6tacr

oK 0ot110.

Zatl