Information Notice 2000-21, 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