Information Notice 1986-74, Reduction of Reactor Coolant Inventory Because of Misalignment of RHR Valves

Reduction of Reactor Coolant Inventory Because of Misalignment of RHR Valves

ML031250156
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, Skagit, Marble Hill
Issue date:	08/20/1986
From:	Jordan E NRC/IE
To:
References
IN-86-074, NUDOCS 8608180091
Download: ML031250156 (6)

1 ^18SSINS OR LE No.: 6835 IN 86-74 UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, DC 20555 August 20, 1986 IE INFORMATION NOTICE NO. 86-74: REDUCTION OF REACTOR COOLANT INVENTORY

BECAUSE OF MISALIGNMENT OF RHR VALVES

Addressees

All boiling water reactor facilities holding an operating license or a

construction permit.

Purpose

This notice is provided to inform recipients of NRC's continuing concern with

the potential for draining the reactor coolant system because of residual heat

removal system (RHR) valve misalignment. This is a recurring situation previ- ously addressed in Information Notice (IN) 84-81 and General Electric Company's

(GE's) Service Information Letter (SIL) 388. This notice is considered an

interim action pending further review of this problem.

Suggestions contained in this notice do not constitute NRC requirements;

therefore, no specific action or written response is required. It is expected, however, that recipients will carefully review the information for applica- bility to their facilities and consider actions to preclude similar problems

from occurring at their facilities.

Description of Circumstances

A number of events involving reduction of reactor coolant inventory because of

RHR valve misalignment have occurred since the issuance of IN 84-81. Six events

that occurred in 1985 have-been selected for inclusion in this notice. A seventh

case was included since RHR was intentionally used to drain water from the

reactor cavity. (Refer to Attachment 1 for diagram and definition of pathways.)

SUSQUEHANNA 2, 04/27/85 While attempting to align B-loop RHR in the shutdown cooling mode, a

portion of the RHR piping was inadvertently drained to the main condenser

during the warmup process. When the operator opened the heat exchanger

bypass valve F048B, water drained rapidly from the vessel, refilling the

RHR piping, and waterhammer occurred. The reactor vessel level decreased

35 inches. Reactor scram and primary containment isolation system (PCIS)

actuation* occurred on the reactor low-level signal. (Pathway 5)

• Typical scram and PCIS actuation set point is +12.5 inches or 162 inches above

active fuel.

8608180091

IN 86-74 August 20, 1986 WNP-2, 05/07/85 to low pressure coolant injection

While shifting from shutdown cooling

valve F004 was opened before shut- (LPCI) lineup, suppression pool suction

shut (valves FOOS & F009 were open).

down cooling suction valve F006 was times of the valves. Water level

The operator did not allow for the stroke set point. The final water

rapidly fell to the scram and PCIS actuation

level was +5 inches. (Pathway 1)

SUSQUEHANNA 1, 05/16/85 failed open while starting C-pump for

The minimum flow bypass valve F064A

FOO9A open. (Pathway 3)

shutdown cooling with valves FOO8A and

SUSQUEHANNA 1, 05/20/85 open while starting A-pump for

The minimum flow bypass valve F064A failed (Pathway 3)

F009A open.

shutdown cooling with valves FOOSA and

SHOREHAM, 07/26/85 to LPCI lineup, the F004 valve was

While shifting from shutdown cooling

FO08 & F009 were open).. Approx- opened before the F006 valve shut (valves was drained to the suppression

Imately 7500 gallons of reactor inventory actuation on the low reactor

PCIS

pool. The incident was terminated by was -10 inches as opposed to

The final water level

water level signal.

(Pathway 1)

the normal level of about +39 inches.

PEACH BOTTOM 2, 09/24/85 from shutdown cooling to the full flow

The 2A RHR pump was being realigned

and F006C open, the discharge valve

test mode. With valves F008A, F009A

in the 2A line, allowing reactor

to the suppression pool F024A was opened the reactor water low-level set

water to flow to the torus. On reaching

actuated to terminate the event. The

point, the reactor scrammed and PCIS 2)

final water level was -10 inches. (Pathway

VERMONT YANKEE, 05/22/86 pool, cavity and reactor, and

During refueling operations, the equipment no one on the refueling floor to

With

spent fuel pool were communicating. than necessary to prevent

room attention

observe level and less control

the point that water was flowing into

the event, water level increased to

level, operators aligned shutdown

the ventilation ducts. To lower water

in this case to stop the overflow, cooling to the torus. Although effectivethe cavity is not recommended in

use of the RHR pump and valves to drain

GE SIL 388.

IN 86-74 August 20, 1986 Discussion:

The RHR system has several modes of operation including the shutdown cooling

mode. Shutdown cooling makes use of the same piping, valves, pumps, and heat

exchangers that the LPCI function uses. The misalignment of shutdown cooling

valves with its potential for RHR system damage and draining of the reactor

coolant system is of regulatory concern.

Generic Letter 83-28, dated July 8, 1983, Required Action 2.2: "Equipment

Qualification and Vendor Interface," paragraph 2, states that "licensees and

applicants shall establish, implement and maintain a continuing program to

ensure that vendor information for safety-related components is complete, current and controlled throughout the life of their plants, and appropriately

referenced or incorporated in plant instructions and procedures." A relevant

vendor communication is GE SIL 388 which states that shutdown cooling 'is

entirely controlled by manual operator actions and is, therefore, subject to

operator error which could result in hydraulic and thermal conditions not

specifically considered in the design process." It recommends review and

upgrading of operating procedures and operator training programs to minimize

operator error during operation of the shutdown cooling mode of RHR.

Possible operator errors identified in SIL 388 include the opening of the F004 valve before the F006 valve is shut, intentional use of shutdown cooling for

vessel level reduction, opening of the minimum flow bypass line, use of the

test return line, and opening of the upper containment pool return line (BWR/6).

This latter possibility is designated pathway 4 in Attachment 1. Also, GE

cautions against the use of RHR shutdown cooling to drain the cavity because of

possible thermal and hydraulic conditions not explicitly considered in the

design process and possible equipment damage.

Since the RHR pumps each have a capacity of 10,000 gpm, two operating pumps can

transfer 20,000 gpm (that is, more than 1,000,000 gallons per hour) from tne

vessel to the suppression pool. Also, the paths involving gravity flow are

through large diameter piping systems with a considerable differential height

between the vessel and the suppression pool. The reactor and cavity, the

equipment pool, and the spent fuel pool above the bottom of the fuel transfer

slot contain around 800,000 gallons of water. Quantities of 5000 to 50,000

gallons have been rapidly drained in previous incidents, usually terminated by

the operation of PCIS. PCIS has mitigated several of the events, although

technical specifications generally do not require PCIS to be operable in modes

where shutdown cooling is required.

Because the problems of draining the vessel through misalignment of the RHR

valves continue to occur in spite of GE and NRC communications alerting

licensees to them, the NRC is considering what further action should be taken.

IN 86-74 August 20, 1986 is required by this information notice.

No specific action or written response please contact the Regional

If you have any questions about this matter, office or this office.

Administrator of the appropriate regional

Edward L ordan, Director

Division f Emergency Preparedness

and En neering Response

Office of Inspection and Enforcement

Mary S. Wegner, IE

(301) 492-4511 Attachments:

Created by RHR Valve

1. Reactor Coolant Inventory Pathways

Misalignment

2. List of Recently Issued IE Information Notices

Attachment 1 .-

(

( C- IN 86-74 August 20, 19g

REACTOR COOLANT INVENTORY

PATHWAYS CREATED BY RHR VALVE

MISALIGNMENT . BWR 3, 4, 5 (&6) I

Attachment 2 IN 86-74 August 20, 1986 LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information Date of

Notice No. Subject Issue Issued to

86-73 Recent Emergency Diesel 8/20/86 All power reactor

Generator Problems facilities holding

an OL or CP

86-72 Failure 17-7 PH Stainless 8/19/86 All power reactor

Steel Springs In Valcor facilities holding

Valves Due to Hydrogen an OL or CP

Embrittlement

86-71 Recent Identified Problems 8/19/86 All power reactor

With Limitorque Motor facilities holding

Operators an OL or CP

86-70 Spurious System Isolation 8/18/86 All GE BWR facilities

Caused By The Panalarm Model holding an OL or CP

86 Thermocouple Monitor

86-69 Scram Solenoid Pilot Valve 8/18/86 All BWR facilities

(SSPV) Rebuild Kit Problems holding an OL or CP

86-68 Stuck Control Rod 8/15/86 All BWR facilities

holding an OL or CP

86-67 Portable Moisture/Density 8/15/86 All NRC licensees

Gauges: Recent Incidents And authorized to possess, Common Violations Of Require- use, transport, and

ments For Use, Transportation, store sealed sources

And Storage

86-66 Potential For Failure Of 8/15/86 All power reactor

Replacement AC Coils Supplied facilities holding

By The Westinghouse Electric an OL or CP

Corporation For Use In Class

1E Motor Starters And

Contractors

86-65 Malfunctions Of ITT Barton 8/14/86 All power reactor

Model 580 Series Switches facilities holding

During Requalification Testing an OL or CP

UL- =)perating License

CP = Construction Permit