Information Notice 2000-21, Detached Check Valve Disc Not Detected by Use of Acoustic and Magnetic Nonintrusive Test Techniques

Detached Check Valve Disc Not Detected by Use of Acoustic and Magnetic Nonintrusive Test Techniques

ML003773068
Person / Time
Issue date:	12/15/2000
From:	Marsh L Operational Experience and Non-Power Reactors Branch
To:
benedict R
References
IN-00-021
Download: ML003773068 (8)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D. C. 20555-0001 December 15, 2000

NRC INFORMATION NOTICE 2000-21: DETACHED CHECK VALVE DISC NOT DETECTED

BY USE OF ACOUSTIC AND MAGNETIC

NONINTRUSIVE TEST TECHNIQUES

Addressees

All holders of operating licenses for nuclear power reactors, except those who have

permanently ceased operations and have certified that fuel has been permanently removed

from the reactor.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert

addressees to the potential that nonintrusive testing (NIT) of check valves may not provide

accurate results if the NIT method was not qualified and if baseline performance was not

established when the valve was known to be operating acceptably. It is expected that

recipients will review the information for applicability to their facilities and consider actions, as

appropriate, to avoid problems. However, suggestions contained in this information notice are

not NRC requirements; therefore, no specific action or written response is required.

Description of Circumstances

During an inservice test of high-pressure safety injection pump P-66A at the Palisades Plant on

June 21, 2000, the pump failed to achieve its hydraulic reference values. The probable cause

of this condition was that piston check valve CK-ES3340 in the P-66A recirculation line was

stuck in mid-position. A simplified system diagram of the Palisades safety injection system is

included as Attachment 2.

The Palisades inservice testing (IST) program designated check valve CK-ES3340 as having

safety functions in both the open and closed positions. Upon discovery of this valve stuck in

mid-position, the licensee designated swing check valve CK-ES3332 to provide the safety

function to close, previously performed by CK-ES3340, in addition to its originally-designated

safety function to open. The open safety function of CK-ES 3332 had been tested previously

under the IST program by verifying that the valve passed the maximum accident condition flow.

NIT had been performed in 1997, and the licensee concluded then that the acoustic monitoring

data provided indications of valve closure. The valve had never been disassembled for internal

inspection.

On June 21, 2000, Palisades performed NIT, using acoustic and magnetic monitoring

techniques, to verify the closure capability of check valve CK-ES3332 as a substitute for the

closure function performed by CK-ES3340. The licensee concluded that the acoustic test data

provided closure indications of the check valve disc impacting its seat and also provided open

indications of the disc impacting the backstop. The analysis of magnetic test data also

indicated that the valve disc had moved to the open position. However, because of changes

that were made to the Palisades NIT data collection software between 1997 and 2000, the

licensee could not trend the data between these tests. No additional testing or examination

was performed on June 21, 2000.

On September 5, 2000, the licensee radiographed valve CK-ES3332 to obtain more actual

data. Radiography revealed that the valve disc and connected swing arm had separated from

the hinge pin and were resting on the bottom of the valve. Opening the check valve to perform

an internal inspection confirmed the radiography and revealed that the swing arm and disc were

intact. There was no indication of service wear on the hinge pin. A subsequent licensee event

report (LER, Reference 1), attributed this condition to improper assembly of the valve during the

plants construction. In addition, the LER stated that the actual condition of CK-ES3332 was

not ascertained in June 2000, during acoustic testing, because the results obtained from the

acoustic testing corresponded with generically expected open and closed indications.

NRC and Industry Guidance on Check Valve NonIntrusive Testing

In accordance with the Code (References 2, 3 and 4), a check valve that is required by 10 CFR

50.55a to be included in the IST program must be exercised to the positions in which it

performs its safety functions. Attachment 1 to NRC Generic Letter 89-04 (Reference 5), details

11 separate NRC Staff Positions on potential generic deficiencies related to IST programs and

procedures. Position 1, Full Flow Testing of Check Valves, states that a check valve's full

stroke to the open position may be verified by passing the maximum required accident- condition flow through the valve. Position 1 also provides guidance on qualifying other

techniques (e.g., establishing a baseline when the valve is known to be in good working order

and specifying adequate acceptance criteria). For backflow testing of check valves, Position 3 states that check valve closure may be verified by visual observation, by an electrical signal

initiated by a position-indicating device, by observation of appropriate pressure indication in the

system, by leak testing, or by other positive means.

Section 4.1.2 of NUREG-1482 (Reference 6) provides guidance on exercising check valves with

flow and on using NIT. It states that nonintrusive techniques may be used to verify the

capability of check valves to open, close, and fully stroke in accordance with quality assurance

program requirements. These techniques are considered "other positive means" in accordance

with requirements for testing the check valve obturator movement (References 7, 8, and 9).

Information on qualification of NIT is given in the summary of NRC public workshops on the

revision of Inspection Procedure 73756 (Reference 10). In response to a question about

expectations for qualification of an NIT method, the NRC stated that a qualified NIT method is

a technique that has been successfully and reliably demonstrated for the examination method

and for the specific valve application. In the late 1980's and early 1990's, the Nuclear Industry Check Valve Group conducted an

experimental research and testing program to evaluate the available NIT technologies to

determine their acceptability and reliability for use in check valve testing (Reference 11). The

group obtained baseline information on check valves and concluded that, with baseline

information available, the NIT methods investigated could detect a missing disc. Their report

also indicates that having a complete operational history of the valve will improve accuracy of

the data evaluation.

Discussion

In accordance with the guidance in Reference 6, the NRC considers NIT acceptable for

inservice testing of check valves provided that the method used is qualified. Qualification

includes establishing a performance baseline when the check valve is in good operating

condition. A check valves performance can then be assessed against this baseline. In order to

meet the check valve obturator testing requirements, the NIT technique must be repeatable.

Both the NRC and industry have provided guidance on the use of NIT, as referenced above.

The only means to determine if an NIT technique will provide accurate and repeatable results

for a specific check valve is to qualify the technique prior to its use. The qualification process

may reveal that certain NIT techniques give inconclusive results for a particular application. For

example, other plant noise sources may affect the sound pattern of the disc striking the valve

backstop or seat, which may affect the results of the acoustic monitoring test. Such issues are

typically addressed in the NIT qualification process and are documented for future reference.

In the case of Palisades, check valve CK-ES3332 had not been verified to be in good operating

condition prior to the use of NIT. When NIT was performed on June 21, 2000, the technique

had not been properly qualified. The individuals who examined the results of the test concluded

incorrectly, based on their experience, that the valve was moving properly to its open and

closed positions. Had the NIT method been qualified for valve CK-ES3332, the initial

examination should have identified the valves improper assembly.

Generic Implications

If NIT techniques used to verify the opening or closing capability of safety-related check valves

are not properly qualified and a baseline established for each individual valve when the valve is

known to be operating acceptably, potentially inadequate valve performance may be

undetectable in the analysis of NIT results. This information notice requires no specific action or written response. If you have any

questions about the information in this notice, please contact the technical contact listed below

or the appropriate Office of Nuclear Reactor Regulation (NRC) project manager.

/RA/

Ledyard B. Marsh, Chief

Events Assessment, Generic Communications

and Non-Power Reactors Branch

Division of Regulatory Improvement Programs

Office of Nuclear Reactor Regulation

Technical contact: J. Colaccino, NRR

301-415-2753 E-mail: jxc1@nrc.gov

Attachments:

1. List of References

2. Palisades Safety Injection System Simplified Diagram

3. List of Recently Issued Information Notices This information notice requires no specific action or written response. If you have any

questions about the information in this notice, please contact one of the technical contacts

listed below or the appropriate Office of Nuclear Reactor Regulation (NRC) project manager.

/RA/

Ledyard B. Marsh, Chief

Events Assessment, Generic Communications

and Non-Power Reactors Branch

Division of Regulatory Improvement Programs

Office of Nuclear Reactor Regulation

Technical contact: J. Colaccino, NRR

301-415-2753 E-mail: jxc1@nrc.gov

Attachments:

1. List of References

2. Palisades Safety Injection System Simplified Diagram

3. List of Recently Issued Information Notices

Distribution:

IN File

PUBLIC

Accession No.: ML003773068 Template No.:NRR-052 To receive a copy of this document, indicate in the box C=Copy w/o attachment/enclosure E=Copy with attachment/enclosure N = No copy

OFFICE EMEB:DE REXB EMEB:DE D:DE C:REXB:DRIP

NAME JColaccino* RBenedict* EImbro/comments JStrosnider* LMarsh

DATE 11/21/00- 12/07/00 11/21/00/11/30/00 11/30/00 12/06/00 / /00

OFFICIAL RECORD COPY CITF

Attachment 1 References

1. LER 50-225/00-04, Discovery of Inoperable Check Valve Results in Plant Shutdown, October 4, 2000. (Accession No. 9810270327)

2. American Society of Mechanical Engineers (ASME) Code, 1986 Edition,Section XI,

Subsection IWV, Inservice Testing of Valves in Nuclear Power Plants, paragraph IWV-

3522.

3. ASME/American National Standards Institute (ANSI), Operations and Maintenance

Standard (OM), Part 10, Inservice Testing of Valves in Light-Water Reactor Power

Plants, 1988 Addenda, paragraph 4.3.2.2(a).

4. ASME OM Code 1996 Addenda, Subsection ISTC, paragraph 4.5.4(a)(1). NUREG-

1482, Guidelines for Inservice Testing at Nuclear Power Plants, April 1995.

5. Generic Letter 89-04, Guidance on Developing Acceptable Inservice Testing

Programs, April 3, 1989.

6. NUREG-1482, Guidelines for Inservice Testing at Nuclear Power Plants, April 1995.

7. ASME Code, 1989 Edition,Section XI, Subsection IWV, paragraph IWV-3522(a).

8. ASME/ANSI OM Part 10, 1988 Addenda, paragraph 4.3.2.4(a).

9. ASME OM Code, 1996 Addenda, Subsection ISTC, paragraph 4.5.4(a)(3).

10. Memorandum from Joseph Calycina (NRC) to file, Summary of Public Workshops Held

in NRC Regions on Inspection Procedure 73756, Inservice Testing of Pumps and

Valves, and Answers to Panel Questions on Inservice Testing Issues, Question 2.3.1, July 18, 1997. (Accession No. 9810270327)

11. Evaluation of Nonintrusive Diagnostic Technologies for Check Valves (NIC-01),

Volume 1, February 1991, transmitted by a letter dated February 20, 1992, to Francis

Grubelich, NRC, from the Nuclear Industry Check Valve Group. (Accession No.

9205280219)

Attachment 2 Attachment 3 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

_____________________________________________________________________________________

Information Date of

Notice No. Subject Issuance Issued to

______________________________________________________________________________________

2000-20 Potential Loss of Redundant 12/11/2000 All holders of operating licenses

Safety Related Equipment Due or construction permits for

to Lack of a High-Energy Line nuclear power reactors

Break Barrier

2000-19 Implementation of Human Use 12/05/2000 All medical use licensees

Research Protocols Involving

U.S. Nuclear Regulatory

Commission Regulated

Materials

2000-18 Substandard Material Supplied 11/29/2000 All 10 CFR Part 50 licensees and

by Chicago Bullet Proof applicants. All category 1 fuel

Systems facilities. All 10 CFR Part 72 licensees and applicants

2000-17 S1 Crack In Weld Area of Reactor 11/16/2000 All holders of OL for nuclear

Coolant System Hot Leg Piping power reactors except those who

At V.C. Summer have ceased operations and have

certified that fuel has been

permanently removed from the

reactor vessel

2000-17 Crack In Weld Area of Reactor 10/18/2000 All holders of OL for nuclear

Coolant System Hot Leg Piping power reactors except those who

At V.C. Summer have ceased operations and have

certified that fuel has been

permanently removed from the

reactor vessel

2000-16 Potential Hazards Due to 10/5/2000 All NRC licensees that process

Volatilization of Radionuclides unsealed byproduct material

2000-15 Recent Events Resulting in 9/29/2000 All radiography licensees

Whole Body Exposures

Exceeding Regulatory Limits

2000-14 Non-Vital Bus Fault Leads to 9/27/2000 All holders of OL for nuclear

Fire and Loss of Offsite Power power reactors

______________________________________________________________________________________

OL = Operating License

CP = Construction Permit