ML102920665

Response to Disputed Notice of Violation (NOV)05000391/2010603-08

ML102920665
Person / Time
Site:	Watts Bar
Issue date:	10/19/2010
From:	Ogle C NRC/RGN-II/DCI
To:	Bhatnagar A Tennessee Valley Authority
References
EA-10-195, IR-10-603
Download: ML102920665 (8)

See also: IR 05000391/2010603

Text

UNITED STATES

NUCLEAR REGULATORY COMMISSION

REGION II

MARQUIS ONE TOWER

245 PEACH TREE CENTER AVENUE, NE

ATLANTA, GEORGIA 30303-1257

October 19, 2010

EA-10-195

Tennessee Valley Authority

Mr. Ashok S. Bhatnagar

Senior Vice President

Nuclear Generation Development and Construction

Tennessee Valley Authority

6A Lookout Place

1101 Market Street

Chattanooga, TN 37402-2801

SUBJECT: RESPONSE TO DISPUTED NOTICE OF VIOLATION (NOV)05000391/2010603-08

Dear Mr. Bhatnagar:

Thank you for the TVA letter dated September 7, 2010, in response to our NOV

05000391/2010603-08 dated August 5, 2010. The Notice described a violation that was

identified during an inspection conducted by the Nuclear Regulatory Commissions (NRCs)

Division of Construction Inspection (DCI).

In the response, TVA disputed NOV 05000391/2010603-08. As base for its denial TVA

indicated the following:

• Westinghouse seismically tested the120VAC Vital Instrument Power Board assembly in

1974 in a configuration which duplicated the actual configuration in the plant.

• Commercial grade replacement breakers were dedicated in 1992 using the guidance of

IEEE 344-1975 Section 6.4, Device Testing.

• The calculated natural frequencies of the front cover panel show it to be rigid. The rigid

clamping arrangement of rear retaining angles and front cover panel do not introduce any

additional flexibility that would require replication of the 1974 testing. The 1974 and 1992

tests demonstrate the original board and breakers remain seismically qualified.

• Subsequent modification to the commercial grade circuit breakers in 2008 were evaluated

as like-for-like and the breakers remained seismically qualified. Calculation WCG-ACQ-

1004 analyzed the effects that were introduced by the modification, demonstrated an

adequate review for suitability of application, and analyzed the impact on other components.

After review and consideration of TVAs response, the NRC has concluded that, for the reasons

given in the enclosure to this letter, the violation occurred as stated in NOV 05000391/2010603-

08. The violation involves the failure to accomplish activities affecting quality in accordance with

10 CFR 50 Appendix B. You are required to provide an additional response in accordance with

10 CFR 2.201. The violation was categorized at Severity Level IV and will remain open until the

NRC has verified implementation of TVAs corrective actions during a subsequent inspection.

A. Bhatnagar 2

In accordance with 10 CFR 2.390 of the NRCs Rules of Practice, a copy of this letter and its

enclosure will be available electronically for public inspection in the NRC Public Document

Room or from the Publicly Available Records (PARS) component of the NRCs document

system (ADAMS). Adams is accessible from the NRC Web site at http://www.nrc.gov/reading-

rm/adams.html (the Public Electronic Reading Room).

If you have any questions regarding this correspondence, please contact Mark Lesser at

404-997-4460.

Sincerely,

/RA/

Charles Ogle, Director

Division of Construction Inspection

Docket Nos.: 50-392

License Nos.: CPPR-92

Enclosure: NRC Evaluation and Conclusion

ML102920665 XG SUNSI REVIEW COMPLETE

OFFICE RII:DCI RII:DCI RII:EICS OE NRR RII RII

SIGNATURE MSL CRO CFE e-mail e-mail TNF GC

NAME M. Lesser C. Ogle C. Evans G. Gulla K. Manoly T. Fanelli G. Crespo

DATE 10/6/10 10/19/10 10/6/10 10/8/10 10/6/10 9/29/10 9/28/10

E-MAIL COPY? YES NO YES NO YES NO YES NO YES NO YES NO YES NO

A. Bhatnagar 3

cc w/encl:

Mr. Gordon P. Arent Mr. M.J. Hellstern

Manager General Manager

New Generation Licensing NGDC Governance & Oversight

Nuclear Generation Development Tennessee Valley Authority

and Construction 3A Blue Ridge Place

WBN Nuclear Plant 1101 Market Street

P.O. Box 2000 Chattanooga, Tennessee 37402-2801

Spring City, Tennessee 37381

Mr. R.M Krich

Mr. Masoud Bajestani Vice President

Vice President Nuclear Licensing

WBN Unit Two Tennessee Valley Authority

WBN Nuclear Plant 3R Lookout Place

Tennessee Valley Authority 1101 Market Street

P.O. Box 2000 Chattanooga, Tennessee 37402-2801

Spring City, Tennessee 37381

Mr. E.J. Vigluicci

Mr. Michael K. Brandon, Manager Assistant General Counsel

Licensing and Industry Affairs Tennessee Valley Authority

WBN Nuclear Plant 6A West Tower

Tennessee Valley Authority 400 West Summit Hill Drive

P.O. Box 2000 Knoxville, Tennessee 37402

Spring City, Tennessee 37381

Lawrence E. Nanney, Director

Mr. Preston D. Swafford Tennessee Department of Environmental

Chief Nuclear Officer Health and Conservation

and Executive Vice President Division of Radiological Health

Tennessee Valley Authority 3rd Floor, L&C Annex

3R Lookout Place 401 Church Street

1101 Market Place Nashville, TN 37243-1532

Chattanooga, Tennessee 37402-2801

Mr. D. E. Grissette

County Executive Site Vice President

375 Church Street WBN Nuclear Plant

Suite 215 Tennessee Valley Authority

Dayton, Tennessee 37321 P.O. Box 2000

Spring City, Tennessee 37381

W.R. Crouch, Manager

WBN Unit 2 Licensing County Mayor

Watts Bar Nuclear Plant P.O. Box 156

Tennessee Valley Authority Decatur, Tennessee 37322

P.O. Box 2000

Spring City, Tennessee 37381 Senior Resident Inspector

WBN Nuclear Plant

Mr. Gregory A. Boerschig U.S. NRC

Plant Manager, WBN Nuclear Plant 1260 Nuclear Plant Road

Tennessee Valley Authority Spring City, Tennessee 37381-2000

P.O. Box 2000

Spring City, Tennessee 37381

A. Bhatnagar 4

Letter to Ashok S. Bhatnagar from Charles R. Ogle dated October 19, 2010

SUBJECT: RESPONSE TO DISPUTED NOTICE OF VIOLATION (NOV)05000391/2010603-08

Distribution w/encl:

L. Raghavan, NRR

S. Campbell, NRR

P. Milano, NRR

C. Evans, RII

L. Douglas, RII EICS

R. Haag, RII, DCP

W. Bearden, RII, WBN Unit 2 SRI

E. Guthrie, RII DRP

R. Monk, RII WBN Unit 1 SRI

OE Mail (OEMAIL)

PUBLIC

cc email distribution w/encl:

Greg Scott

Tennessee Valley Authority

Electronic Mail Distribution

NRC EVALUATION AND CONCLUSION

The violation was identified during an inspection conducted by the Nuclear Regulatory

Commissions (NRC) Division of Construction Inspection (DCI) at Watts Bar Nuclear Station

Unit 2 in Spring City Tennessee. TVA disagreed with the violation by letter dated

September 7, 2010, and provided the following bases:

• Westinghouse seismically tested the120VAC Vital Instrument Power Board assembly in

1974 in a configuration which duplicated the actual configuration in the plant.

• Commercial grade replacement breakers were dedicated in 1992 using the guidance of

IEEE 344-1975 Section 6.4, Device Testing.

• The calculated natural frequencies of the front cover panel show it to be rigid. The rigid

clamping arrangement of rear retaining angles and front cover panel do not introduce any

additional flexibility that would require replication of the 1974 testing. The 1974 and 1992

tests demonstrate the original board and breakers remain seismically qualified.

• Subsequent modification to the commercial grade circuit breakers in 2008 were evaluated

as like-for-like and the breakers remained seismically qualified. Calculation WCG-ACQ-

1004 analyzed the effects that were introduced by the modification, demonstrated an

adequate review for suitability of application, and analyzed the impact on other components.

A. Specific Bases for Disputing NOV 05000391/2010603-08

In its letter of September 7, 2010, TVA disagreed with the NRCs conclusion regarding the 1992

qualification of circuit breakers and subsequent deficient equivalency evaluation at Watts Bar

Unit 2.

TVA cited the following as bases for disputing the NRCs conclusion that a violation occurred:

1. Westinghouse seismically tested the 120VAC Vital Instrument Power Board assembly with

Heinemann Model CF2-Z51-1 circuit breakers in 1974, mounted in place solely by clamping

pressure applied by the front cover pushing twelve breakers against the rear angle supports.

There were no additional screws to secure the breaker to the frame. This configuration

duplicated the actual configuration in the plant.

2. Commercial grade replacement breakers were dedicated in 1992 by attaching an individual

breaker to the vibratory source with bolting. IEEE 344-1975 section 6.4, Device Testing,

allows a device, intended to be mounted on a panel, to be mounted directly to the shake

table if the in-service excitation can be simulated. A 3g input motion (which exceeded the

2.72g highest measured acceleration [seismic demand] in the 1974 test) was applied.

3. The retention of breakers in the as-constructed board assembly is by a clamping

arrangement provided by two rear retaining angle iron members and the front cover panel.

The calculated natural frequencies of the front cover panel in the three directions were in

excess of 33 Hz and rigid. The rigid clamping arrangement of rear retaining angles and the

front cover panel do not introduce any additional flexibility that would require replication of

the 1974 testing. The 1974 and 1992 tests demonstrate the original board and breakers

remain seismically qualified.

4. Subsequent modification to the new breakers in 2008 added a Micarta plate and bolts to

attach it. Calculation WCG-ACQ-1004 addressed the qualification of the circuit breakers

with the Micarta plate and concluded that the component (i.e., circuit breaker) remained

seismically qualified under like-for-like conditions per the 1992 seismic qualification device

2

test. Calculation WCG-ACQ-1004 analyzed the effects that were introduced by the

modification, demonstrated an adequate review for suitability of application, and analyzed

the impact on other components.

B. NRC Evaluation of Licensees Response

The NRC carefully reviewed TVAs response and concludes that the violation occurred as

stated in the Notice of Violation. The bases for this determination are as follows:

1. The staff was unable to substantiate TVAs assertion that the 1974 test replicated the

mounting configuration in the plant. The staffs review of the 1974 test records and

configuration drawings revealed conflicting and inconsistent information. TVA cites the 1974

Westinghouse qualification and it references Westinghouse drawings CO-33419-MKE-M2

and M3 for the as-constructed configuration of the 120VAC Vital Instrument Power Board

assembly. The Westinghouse drawings are inconclusive in determining if fasteners secured

the circuit breakers and incorrectly show the orientation of the angle iron supports and the

profile of the front cover plate. TVA drawing 45N7OI-4 R2 also depicts the as-constructed

Watts Bar configuration of the 120VAC Vital Instrument Power Board assembly. The

method of securing the circuit breakers, angle iron supports for the back of the breakers,

and the profile for the front cover plates shown in the two sets of drawings are different.

Drawing 45N7OI-4 R2 shows fasteners (screws or bolts) securing the circuit breakers to the

rear angle iron supports, which are not in the as-constructed configuration, but accurately

shows the orientation of the angle iron supports and the profile of the front cover plates that

clamp the circuit breakers against the angle iron supports. Additionally the inside face of the

front cover plate of the existing Watts Bar power boards has stiffening supports both

vertically and horizontally on each panel. Neither the Westinghouse nor the TVA drawings

show these supports in the drawings. TVA has not reconciled these differences. The staff

was unable to verify that the existing Watts Bar 120VAC Vital Instrument Power Board

assembly configuration is the same as the 1974 qualification test configuration.

2. IEEE-344-1975, for the commercial grade dedication testing, Section 6.1.1, Mounting, states

in part, for the equipment to be tested, the mounting method shall be the same as that

recommended for actual service. TVA incorrectly cites IEEE 344-1975; Section 6.4 which

allows components mounted on a panel or plate, i.e. flat surfaces, (flat doors, flat top, flat

back, or flat sides), without any other interposing parts that could interfere with those parts

to be mounted directly to a seismic test table fixture. Mounting such components to a test

table on a simulated flat plate instead of the actual panel, in that case, would adequately

simulate the mounting of those types of components. The applicant described the in-service

mounting in their response as a 36 front panel with two horizontal angle iron supports in the

rear and that the breakers were held in place solely by the clamping pressure applied by the

front cover pushing the twelve breakers against the rear angle supports. The circuit

breakers described by the applicant do not represent components mounted on a panel that

can be tested in accordance with Section 6.4 of IEEE-344. Furthermore, the 1992

qualification report specified that it applies only to circuit breakers being secured by

fasteners. The 1992 qualification report for the circuit breakers stated that they were

mounted for testing with screws, to a test table plate, in a manner that simulates the normal

in-plant mounting. The TVA drawing 45N7OI-4 R2 with the error depicting fasteners was

created in the 1970s and was available for the 1992 qualification personnel. TVA has not

adequately resolved these inconsistencies.

3

3. TVA did not support their assertion that the front cover panel is rigid and that the clamping

arrangement of rear retaining angles in combination with the front cover panel are rigid.

TVA in its response letter stated, The calculated natural frequencies of the front cover panel

in the three directions were also in excess of 33 Hz and rigid. When asked to produce the

calculation for examination, TVA stated that the calculation was informal and not retained

and therefore could not be presented for examination. Furthermore, according to drawings

CO-33419-MKE-M2 & M3 the 120VAC Vital Instrument Power Boards construction consists

of panels and angle iron supports that are bolted together. The front cover panels are

bolted through threads in the steel angle iron. IEEE 344-1987 clarifies that, such cabinets

with bolted doors or panels, produce impacts, rattling, chatter, or banging and these impacts

are transmitted throughout the equipment and result in increased acceleration levels at

frequencies much higher than the original frequencies imposed by the shake table. A low

frequency input thereby produces high-frequency responses that may adversely affect

devices mounted in the equipment and must be considered in their qualification. Therefore,

an engineering analysis was necessary to ascertain the adequacy of the power boards and

circuit breakers; however, TVA did not perform an engineering analysis nor provide an

adequate basis that supports a conclusion that the panel arrangement is rigid and not

flexible.

4. TVA did not perform an adequate evaluation to support a conclusion that the 2008

modification of the newest circuit breakers are like-for-like replacements to those circuit

breakers tested in 1974 or 1992. The new circuit breakers were determined by TVA, on or

before July 2008, to be different in dimension from the circuit breakers dedicated in 1974 or

1992 in that they no longer fit into the 120VAC Vital Instrument Power Boards by the

clamping arrangement and had to be modified to fit. Since the new circuit breakers are field

modified with the Micarta plate to fit into the 120VAC Vital Instrument Power Boards, the

new circuit breakers are not like-for-like to the prior circuit breakers. Before September 7,

2010 TVA had never determined the critical characteristics necessary to enable the circuit

breakers to perform their function under design basis conditions and from the time the circuit

breakers were recognized to be different, TVA has not performed an equivalency evaluation

of the modified commercial grade circuit breakers in relation to adequacy or performance.

TVA states that WCG-ACQ-1004 analyzed the effects that were introduced by the new

modification to the circuit breaker but WCG-ACQ-1004 section 7, computation and analysis,

only states that the circuit breakers depth changed by 1/4 inch and that the model number

remained the same. TVA, on that basis, deemed the changes to be minor and thus the new

circuit breaker was seismically qualified under like-for-like conditions to the prior circuit

breakers. The 120VAC Vital Instrument Power Boards require the dimension that changed

as the critical dimension necessary to adequately seat the circuit breakers into the clamping

arrangement for design basis conditions. Calculation WCG-ACQ-1004 does not evaluate

the design basis performance of the new circuit breaker with the changes and new

modifications but rather evaluates the structural failure characteristics of the new Micarta

plate, the bolts used to attach it, and the power board floor anchor bolts each as separate

components of the power boards. In addition, TVA has not presented any evidence of the

dimensional comparison between the back of the front cover plate and the front of the angle

iron to the circuit breakers dimensional critical characteristic and how it is maintained during

design basis conditions. The depth dimension is critical and must be maintained across the

width and height of the clamping arrangement over time so that all of the 12 circuit breakers

across the front cover plate are completely secured.

Additionally, the staff has observed that some of the circuit breakers currently installed in the

120VAC Vital Instrument Power Boards do not appear to be adequately seated into the

power boards clamping arrangement. The staff provided this information and concerns on

4

these circuit breakers to TVA. The staff has further observed that TVA does appear to have

adequate quality controls to ensure the clamping arrangement is maintained or how the

circuit breakers are replaced and adequately re-seated between the angle iron and the front

panel cover, but appears to rely on skill of the craft. Furthermore, even though TVA asserts

that the 1974 test seated the circuit breakers in the clamping arrangement and that they

seemed to perform adequately, TVA has not yet evaluated any aging effects from the

pressure the clamping arrangement provides over time. TVA has not evaluated if the

clamping arrangement requires maintenance to maintain the critical dimension. The

manufacturers design of the circuit breakers is to mount by four screws not by the pressure

from the clamping arrangement, as evidenced by the four mounting tabs built into the circuit

breakers, one at each corner. Because the body of the circuit breakers consists of two

pieces of plastic held together by four small rivets and the plastic body secures and aligns

the internal mechanisms of the circuit breaker, the pressure exerted over time may deform

and degrade the alignment critical to their performance. The staff has determined that

calculation WCG-ACQ-1004, as presented, is not an adequate evaluation of the new

changes to the circuit breakers and does not analyze circuit breaker performance.

NRC Conclusion

On the basis of the foregoing, the NRC concludes that: (1) The as-constructed 120VAC Vital

Instrument Power Board drawings for the 1974 seismic testing cannot be verified to match the

as-constructed configuration of the TVAs current 120VAC Vital Instrument Power Boards. (2)

IEEE 344-1975 stipulates that, the mounting of equipment to be tested shall be the same as that

recommended for actual service and TVA incorrectly applied this standard. (3) The 120VAC

Vital Instrument Power Boards are not confirmed to be rigid assemblies. (4) The newly acquired

commercial grade circuit breakers were not adequately evaluated as like-for-like as replacement

circuit breakers. The calculation WCG-ACQ-1004 is not an adequate equivalency evaluation.

Therefore, the violation occurred as stated in the Notice.