ML103300217
| ML103300217 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 11/24/2010 |
| From: | Bajestani M Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML103300217 (6) | |
See also: IR 05000391/2010603
Text
Valley Authority, Post Office Box 2000, Spring City, Tennessee
37381-2000
10 CFR 2.201 November 24, 2010 U.S. Nuclear Regulatory
Commission
ATTN: Document Control Desk Washington, D.C. 20555-0001
Watts Bar Nuclear Plant, Unit 2 NRC Docket No. 50-391 Subject: Watts Bar Nuclear Plant Unit 2 -Reply to Notice of Violation 05000391/2010603-08
-Failure to Adequately
Evaluate and Qualify Molded Case Circuit Breakers References:
1. NRC letter to TVA, 'Watts Bar Nuclear Plant Unit 2 Construction
-NRC Integrated
Inspection
Report 05000391/2010603
and Notice of Violation," dated August 5, 2010 (ML1 02170465)2. TVA letter to NRC, "Watts Bar Nuclear Plant (WBN) Unit 2 -Denial of Notice of Violation (NOV)05000391/2010603-08, Failure to Adequately
Evaluate and Qualify Molded Case Circuit Breakers," dated September
7, 2010 (ML1 02520435)3. TVA letter to NRC, 'Watts Bar Nuclear Plant (WBN) Unit 2 -Denial of Notice of Violation (NOV)05000391/2010603-08, Failure to Adequately
Evaluate and Qualify Molded Case Circuit Breakers -Additional
Information," dated October 15, 2010 (ML102880493)
4. NRC letter to TVA, "Response
to Disputed Notice of Violation (NOV)05000391/2010603-08," dated October 19, 2010 (ML102920665)
The purpose of this letter is to further respond to Notice of Violation
391/2010603-08,"Failure to Adequately
Evaluate and Qualify Molded Case Circuit Breakers." NRC issued the NOV in a letter dated August 5, 2010 (Reference
1). TVA initially
denied the violation
in a letter dated September
7, 2010 (Reference
2), and provided additional
information
in a letter dated October 15, 2010 (Reference
3). NRC subsequently
U.S. Nuclear Regulatory
Commission
Page 2 November 24, 2010 concluded
that the violation
occurred as stated in a letter dated October 19, 2010 (Reference
4).TVA admits that the violation
occurred and provides its reply in Enclosure
1.Enclosure
2 provides the list of commitments
made in this letter.The schedule for submitting
this reply was discussed
between William Crouch and Mark Lesser on November 19, 2010. If you have any questions, please contact William Crouch at (423) 365-2004.I declare under penalty of perjury that the foregoing
is true and correct. Executed on the 2 4 th day of November, 2010.Sincerely, 9/Masoud stani Watts r nit 2 Vice President Encl ures 1. TVA's Reply to the Notice of Violation
391/2010603-08
2. List of Commitments
cc (Enclosures):
U. S. Nuclear Regulatory
Commission
Region II Marquis One Tower 245 Peachtree
Center Ave., NE Suite 1200 Atlanta, Georgia 30303-1257
NRC Resident Inspector
Unit 2 Watts Bar Nuclear Plant 1260 Nuclear Plant Road Spring City, Tennessee
37381
Enclosure
I Watts Bar Nuclear Plant (WBN) Unit 2"Response
to Notice of Violation (NOV)05000391/2010603-08" Description
of the Violation"10 CFR 50, Appendix B, Criterion
Ill, "Design Control, "states that measures shall be established
for the review for suitability
of application
of materials, parts, and equipment that are essential
to the safety-related
functions
of the structures, systems, and components (SSCs). The design control measures shall provide for verifying
or checking the adequacy of design, such as by the performance
of design reviews, by the use of alternate
or simplified
calculational
methods, or by the performance
of a suitable testing program. Where a test program is used to verify the adequacy of a specific design feature in lieu of other verifying
or checking processes, it shall include suitable qualifications
testing of a prototype
unit under the most adverse design conditions.
Contrary to the above, measures used to review the suitability
of application
of materials, parts, and equipment
essential
to the safety-related
functions
of molded case circuit breakers and measures to provide for the verification
of checking the adequacy of design, such as, calculational
methods, performing
a suitable test program, including qualifications
testing of a prototype
unit under the most adverse design conditions, were not adequate in that: Example I On October 5, 2009, the applicant
installed
molded case circuit breakers into the 120VAC vital instrument
power boards; however, the test program used to seismically
qualify a prototype
circuit breaker failed to use a suitable mounting method that reflected the most adverse mounting condition." TVA Response: TVA admits that the violation
occurred.Reason For The Violation
-Example 1: The reason for this violation
is that Calculation
WCG-ACQ-1
004 failed to fully establish that (1) the 1992 test mounting represented
a suitable mounting method and that (2) the 1992 test bounded the configuration
of the breakers installed
in 2009. The calculation
should have identified
that the method of support for breakers within the board was a rigid mounting system which would have justified
the 1992 testing for replacement
breakers.Corrective
Steps That Have Been Taken And The Results Achieved (Example 1): 1. TVA performed
Calculation
WCG-ACQ-1301
to verify the rigidity of the panel assembly.Corrective
Steps That Will Be Taken: 1. TVA will revise calculation
WCG-ACQ-1004
to address the method of support for breakers within the board as a rigid mounting system which will validate taking credit for the 1992 replacement
breaker testing.E1-1
Enclosure
I Watts Bar Nuclear Plant (WBN) Unit 2"Response
to Notice of Violation (NOV)05000391/2010603-08" 2. As an enhancement
to address any potentially
misaligned
breakers, TVA will review WBN maintenance
and Unit 2 refurbishment
procedures
to ensure that the design basis for the breakers is maintained
by: 1) that the procedures
provide sufficient
guidance that the breakers make positive contact with the angles in the rear, and 2)that the breakers project appropriately
through the front-face
panel openings after any maintenance
involving
full or partial removal of the front-face
panel. In addition, the review will determine
whether directions
are needed to avoid excessive
clamping pressure and to implement
simple checks to status and correct for minor irregularities
in contact between the Micarta insulation
board and rear angles. Based on this review, TVA will determine
the appropriate
implementing
documents
to be revised.3. TVA will evaluate the installed
breakers to ensure breaker operation
will not be affected by the applied clamping breakers.Date When Full Compliance
Will Be Achieved.TVA will be in full compliance
by March 18, 2011.Example 2"On September
3, 2009, the applicant
failed to perform an adequate review for suitability
of application
parts and material used to modify dimensional
critical characteristics
in molded case circuit breakers;
further, the applicant
failed to verify the adequacy of design for the modification
and the effects on essential
safety related functions
of the circuit breakers." Reason For The Violation
-Example 2: The reason for this violation
is that the manufacturer
made a production
change to the breaker configuration
but did not revise the model number or publish schematics
to reflect a component
change. As a result, TVA failed to identify a change in a critical characteristic (i.e., the required mounting depth between the front face and the rear angles) and the resulting
impact on device seismic qualification
and functionality.
Rather than performing
a new equivalency
evaluation, TVA applied a technical
evaluation
for the original breakers and concluded
that the breakers were seismically
and functionally
qualified.
Corrective
Steps That Have Been Taken And The Results Achieved (Example 2): 1. TVA performed
an equivalency
evaluation
for the reconfigured
Heinemann
breakers that identifies
the critical characteristics, addresses
the role of the Micarta insulation
board in restoring
the needed mounting depth for contact between the rear angles and front-face
panel, and addresses
seismic qualification
requirements.
2. A unique identifier (CATID) was established
for the reconfigured
breaker to be used for future purchases
of reconfigured
breakers for WBN Units 1 and 2. Use of a unique ID will distinguish
the reconfigured
breakers from the original breakers.E1-2
Enclosure
I Watts Bar Nuclear Plant (WBN) Unit 2"Response
to Notice of Violation (NOV)05000391/2010603-08" 3. As an enhancement, TVA updated both the TVA and Westinghouse
drawings to ensure consistency
between drawings and with the installed
configuration.
Corrective
Steps That Will Be Taken: 1. Instructions
will be issued to procurement
and engineering
organizations
providing the necessary
direction
to use the unique CATID described
above which will distinguish
the reconfigured
breakers from the original breakers.
The CATID for original breakers will be retained to support the existing qualification
of replacement
original breakers procured in the past.2. TVA will revise calculation
WCG-ACQ-1004
to confirm the design basis performance
of the reconfigured
breaker in support of the equivalency
evaluation (i.e., demonstrate
the breaker will function as designed with the current configuration
of breaker and spacer board attachment
in the clamping arrangement
of rear angles and front-face
panel sections).
Date When Full Compliance
Will Be Achieved.TVA will be in full compliance
by March 18, 2011.E1-3
I ýEnclosure
2 List of Commitments
Example 1 1. TVA will revise calculation
WCG-ACQ-1004
to address the method of support for breakers within the board as a rigid mounting system which will validate taking credit for the 1992 replacement
breaker testing.2. As an enhancement
to address any potentially
misaligned
breakers, TVA will review WBN maintenance
and Unit 2 refurbishment
procedures
to ensure that the design basis for the breakers is maintained
by the following:
1) that the procedures
provide sufficient
guidance that the breakers make positive contact with the angles in the rear, and 2) that the breakers project appropriately
through the front-face
panel openings after any maintenance
involving
full or partial removal of the front-face
panel. In addition, the review will determine
whether directions
are needed to avoid excessive
clamping pressure and to implement
simple checks to status and correct for minor irregularities
in contact between the Micarta insulation
board and rear angles. Based on the above review, TVA will determine
the appropriate
implementing
documents
to be revised.3. TVA will evaluate the installed
breakers to ensure breaker operation
will not be affected by the applied clamping breakers.Example 2 1. Instructions
will be issued to procurement
and engineering
organizations
providing the necessary
direction
to use the unique CATID described
above which will distinguish
the reconfigured
breakers from the original breakers.
The CATID for original breakers will be retained to support the existing qualification
of replacement
original breakers procured in the past.2. TVA will revise calculation
WCG-ACQ-1004
to confirm the design basis performance
of the reconfigured
breaker in support of the equivalency
evaluation (i.e., demonstrate
the breaker will function as designed with the current configuration
of breaker and spacer board attachment
in the clamping arrangement
of rear angles and front-face
panel sections).
Date When Full Compliance
Will Be Achieved.TVA will be in full compliance
by March 18, 2011.E2-1