Information Notice 1986-38, Deficient Operator Actions Following Dual Function Valve Failures

Deficient Operator Actions Following Dual Function Valve Failures

ML031250028
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, 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, Crane
Issue date:	05/20/1986
From:	Jordan E NRC/IE
To:
References
IN-86-038, NUDOCS 8605150469
Download: ML031250028 (5)

11$ ORIGINA

SSINS No.:

6835 IN 86-38

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C.

20555

May 20, 1986

IE INFORMATION NOTICE NO. 86-38:

DEFICIENT OPERATOR ACTIONS FOLLOWING

DUAL FUNCTION VALVE FAILURES

Addressees

All nuclear power facilities holding an operating license (OL) or a construction

permit (CP).

Purpose

This notice is provided to alert licensees to recent events that resulted from

confusion regarding the proper actions to be taken on failure of dual function

valves (e.g., those that must accommodate emergency core cooling system flow

and also provide containment isolation). It is expected that recipients will

review this information for applicability to their facilities and consider

actions, if appropriate, to preclude similar problems at their facilities.

However, the suggestions contained in this notice do not constitute NRC

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

Description of Circumstances

The emergency core cooling systems for all light water reactors (LWRs) are

equipped with numerous valves that serve both core cooling functions and

containment isolation functions.

The failure of one of these valves to func- tion as designed results in the degradation of at least one of its safety

functions. The following events illustrate instances in which one of the

functions was not promptly recognized following various types of failures.

Peach Bottom Unit 3:

On January 7, 1985, a residual heat removal (RHR) system

torus spray valve malfunctioned following a reactor core isolation cooling

(RCIC) system test.

The valve had been opened to provide suppression pool

cooling for the test and could not be reclosed using the attached motor operator.

To satisfy its containment isolation function, the valve was closed with a

wrench, deactivated, and declared inoperable.

However, the licensee failed to

declare the torus cooling function of the RHR train inoperable. On January 15, with the unit operating at 87 percent power and one emergency diesel generator

inoperable, causing the equipment including the remaining RHR train to be

inoperable, the NRC Resident Inspector discovered that the previously described

train of RHR was inoperable as a result of the closed torus spray valve.

The

licensee declared an "Unusual Event" and began an orderly shutdown of the unit.

8605150469

IN 86-38 May 20, 1986 The operability of the containment cooling mode of RHR requires the operability

of such equipment as the RHR pumps, the RHR heat exchangers, an open flow path

to the containment and the high pressure service water (HPSW) system.

However, review of the Peach Bottom Unit 3 Technical Specifications by the resident

inspectors revealed that only the HPSW system is specified for containment

cooling system operability.

It is believed that the absence of the usual open

flow path requirement statement in the plant technical specifications contri- buted to the failure to declare the RHR train inoperable.

The licensee agreed

to provide interim administrative controls for ensuring operability of the

containment cooling subsystem until the issue is permanently addressed through

a revision to the plant technical specifications or by some other means.

Brunswick Units 1 and 2:

On May 23, 1984, operations personnel at Unit 2

observed that the minimum flow valve for the 2A core spray system (CSS) pump

would not stay in the closed position following receipt of a "close" signal

from the remote manual operator in the control room.

(These valves do not

receive a close signal on actuation of the containment isolation system.)

Engineering personnel determined that the control logic for the minimum flow

valves was such that the valves would reopen after closure whenever a low flow

condition was sensed in the core spray line, including conditions in which the

CSS pumps were not running.

On June 1, the normally open minimum flow valves for the CSS trains in both

units were declared inoperable, closed, and deactivated in accordance with the

technical specification requirement for inoperable primary containment isola- tion valves (PCIVs).

The action statement requires that the line be isolated

if the valve has not been restored to operability within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

The technical specifications did not explicitly list an open minimum flow path

as a requirement for CSS operability, and the licensee failed to declare the

CSS trains inoperable.

The licensee did establish procedures intended to

ensure effective operator action to minimize the potential for pump damage in

the event of a CSS pump start.

However, from subsequent discussions with the

pump vendor, the licensee learned that damage to the CSS pumps could occur in

as little as 1 minute of operation at shutoff head without the required minimum

flow.

The plant staff re-evaluated the situation and concluded that the risk

of pump damage with the valves closed was unacceptable. On June 12, the minimum

flow valves were reopened and actuator power was restored.

Administrative

controls and special procedures were implemented to ensure closure of the

valves when required for containment isolation.

The licensee plans to modify

the logic to allow remote isolation capability for the valves when their

associated pumps are not running so that minimum flow and containment isolation

functions can both be ensured.

Dresden Unit 3:

On February 8, 1983, a low pressure coolant injection (LPCI)

system suppression pool suction valve was cycled closed and failed to reopen.

The valve, which provides both an emergency core cooling system (ECCS) and a

containment isolation function, was then manually opened and electrically

deactivated.

This ensured the LPCI function of the valve, but negated the

IN 86-38 May 20, 1986 containment isolation-function.

Because the swing diesel generator that

supports the redundant"train of LPCI was out of service, an "Unusual Event"

was declared, and unit shutdown was initiated.

In reviewing the event, it was noted that, during the period when the valve

was deactivated in the open position, the licensee did not declare the valve

inoperable or enter the technical specification action statement for an

inoperable PCIV.

Although the LPCI suction valves are listed in the Dresden

Final Safety Analysis Report (FSAR) as containment isolation valves, they were

not listed as such in the technical specifications.

The licensee was requested

to submit an application for a license amendment to add to the technical

specification PCIV list all dual function valves not already listed.

Discussion:

The locations and purposes of dual function valves are diverse. They are found

in the suction lines, discharge lines, and minimum flow lines of a variety of

diverse ECCS pumps.

Some of the suction sources are inside containment, and

some are outside.

Some recirculation paths penetrate containment, and some do

not.

In general, limiting conditions for operation (LCOs) for inoperable PCIVs allow

reactor power operations to continue provided that at least one valve in the line

having the inoperable valve is closed.

However, in the case of an inoperable

dual function valve, this generally would defeat the ECCS function of the line

and would require entry into the action statement for an inoperable ECCS train.

Alternatively, the decision to maintain the ECCS function generally requires

entry into the action statement for an inoperable PCIV.

The operating staff occasionally may have difficulty determining the most

appropriate valve position (open or closed) and valve technical specification

requirement status (enabled or disabled) when a dual function valve fails.

This

difficulty is compounded when the technical specifications are not specifically

provided in the plant license for one or the other function of the failed valve, as illustrated by the events described.

With regard to the technical specifications for operability of safety systems, all licensees were requested by a generic letter dated April 10, 1980, to adopt

the standard definition that had been developed for NRC's Model Technical

Specifications.

That definition requires all necessary attendant instrumenta- tion, controls, normal and emergency electrical power sources, cooling or seal

water, lubrication, or other auxiliary equipment that are required for the

system to perform its function(s) to be capable of performing their support

functions.

IN 86-38 -

May 20, 1986 No specific action or written response is required by this information notice.

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

Administrator of the appropriate NRC regional office or this office.

'Edard~./ordan, Drector

Divisi

of Emergency Preparedness

and Egineering Response

Office of Inspection and Enforcement

Technical Contacts: S. M. Long, NRR

(301) 492-8413

E. J. Leeds, AEOD

(301) 492-4445 Attachment:

Attachment 1

IN 86-38

May 20, 1986

LIST OF RECENTLY ISSUED

IE INFORMATION NOTICES

Information

Date of

Notice No.

Subject

Issue

Issued to

86-37

Degradation Of Station

Batteries

Change In NRC Practice

Regarding Issuance Of

Confirming Letters To

Principal Contractors

5/16/86

5/16/86

86-36

86-35 Fire In Compressible Material 5/15/86

At Dresden Unit 3

86-34

86-33

86-32

Improper Assembly, Material

Selection, And Test Of Valves

And Their Actuators

Information For Licensee

Regarding The Chernobyl

Nuclear Plant Accident

Request For Collection Of

Licensee Radioactivity

Measurements Attributed To

The Chernobyl Nuclear Plant

Accident

Unauthorized Transfer and

Loss of Control of

Industrial Nuclear Gauges

Design Limitations of

Gaseous Effluent Monitoring

Systems

Effects of Changing Valve

Motor-Operator Switch

Settings

5/13/86

5/6/86

5/2/86

5/6/86

4/29/86

4/25/86

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

Fuel cycle licensees

and Priority 1 material

licensees

All power reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or a CP

All power reactor

facilities holding

an OL or a CP

All power reactor

facilities holding

an OL or a CP

86-31

86-30

86-29 OL = Operating License

CP = Construction Permit