ML103300217

Watts Bar Nuclear Plant Unit 2 - Reply to Notice of Violation 05000391/2010603-08 - Failure to Adequately Evaluate and Qualify Molded Case Circuit Breakers

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

Tennessee

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