Information Notice 1989-41, Operator Response to Pressurization of Low-Pressure Interfacing Systems

Operator Response to Pressurization of Low-Pressure Interfacing Systems
	ML031180816
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, Crane
Issue date:	04/20/1989
From:	Rossi C; Office of Nuclear Reactor Regulation
To:	;
References
	IN-89-041, NUDOCS 8904140042
	Download: ML031180816 (6)
	v • d • e

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C.

20555

April 20, 1989

NRC INFORMATION NOTICE NO. 89-41: OPERATOR RESPONSE TO PRESSURIZATION

OF LOW-PRESSURE INTERFACING SYSTEMS

Addressees

All holders of operating licenses or construction permits for nuclear power

reactors.

Purpose

This information notice is being provided to alert addressees to potential

problems that may arise from the lack of proper procedures to deal with un- expected pressurization of systems designed for low operating pressure such

as the residual heat removal (RHR) system.

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 March 9, 1989, when Vogtle Unit 2 was in Mode 3 preparing for initial

criticality, the reactor coolant system (RCS) leakage exceeded Technical

Specification limits. The leakage was observed during a surveillance test

on a cold-leg swing check valve that acts as the inboard pressure isolation

boundary between the RCS and the low-pressure RHR system. The RHR system

had been taken out of service, but the pressure in it did not reduce to the

expected level. To relieve the RHR system pressure, operators opened two

normally locked-closed valves that connect the RHR system to the refueling

water storage tank (RWST), thereby venting RCS coolant to the tank, and from

there, to the atmosphere. The action they took to depressurize the RHR system

was inappropriate and taken without the benefit of proper procedures.

Subsequent investigations determined that the inboard cold-leg check valve in

question had experienced abnormal wear.

The operators appear to have considered

possible leakage into the RHR.system, such as leakage through check valves and

through isolation valves from the chemical and volume control system.

However, the action taken did not reflect an awareness of the potential seriousness of

such leakage.

8904140042 7.ZA--

IN 89-41 April 20, 1989 Discussion:

During this event, public safety was not adversely affected at Vogtle Unit 2 because there was no fission product inventory in the reactor.

Also, the

potential for damage to the RHR system was minimal because the leakage was

well within the relieving capacity of the systemi.

However, leakage of RCS

coolant into systems such as the RHR system and responses to such events by

operators have been sources of longstanding concern because of the potential

for the so-called "Event V" or the "interfacing system loss-of-coolant ac- cident." It is important that licensees have proper procedures that will

enable operators to take only appropriate actions to respond to unexpected

or unexplained pressurization of systems such as the RHR system.

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.

s.Director

Division of Operational Events Assessment

Office-of-Nuclear- Reactor Regulation---

Technical Contact:

N. Prasad Kadambi, NRR

(301) 492-1153 Attachment: List of Recently Issued NRC Information Notices

Attachment

IN 89-41

April 20, 1989 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information

Date of

Notice No.

Subject

Issuance

Issued to

88-75,

Supplement 1

Disabling of Diesel

Generator Output Circuit

Breakers by Anti-Pump

Circuitry

4/17/89

All holders of OLs

or CPs for nuclear

power reactors.

89-40

Unsatisfactory Operator Test

Results and Their Effect on

the Requalification Program

List of Parties Excluded

from Federal Procurement

or Non-Procurement Programs

4/14/89

4/5/89

All holders of OLs

or CPs for nuclear

power reactors.

All holders of OLs

or CPs for nuclear

power reactors.

89-39

89-38 Atmospheric

Failures at

Units 1, 2, Dump Valve

Palo Verde

and 3

4/5/89

All holders of OLs

or CPs for nuclear

power reactors.

89-37

89-36

88-86, Supp. 1

89-35

Proposed Amendments to

40 CFR Part 61, Air

Emission Standards

for Radionuclides

Excessive Temperatures

in Emergency Core Cooling

System Piping Located

Outside Containment

Operating with Multiple

Grounds in Direct Current

Distribution Systems

Loss and Theft of Un- secured Licensed Material

Disposal of Americium

Well-Logging Sources

4/4/89

3/31/89

3/30/89

3/30/89 All U.S. NRC licensees.

All holders of OLs

or CPs for nuclear

power reactors.

All holders of OLs

or CPs for nuclear

power reactors.

All U.S. NRC byproduct, source and special

nuclear material

licensees.

All holders of an

NRC specific license

authorizing well- logging activities.

89-34 OL = Operating License

CP = Construction Permit

IN 89-41 April 20, 1989 Discussion:

During this event, public safety was not adversely affected at Vogtle Unit 2 because there was no fission product inventory in the reactor. Also, the

potential for damage to the RHR system was minimal because the leakage was

well within the relieving capacity of the system.