ML17200C945

Perry Nuclear Power Plant - Response to NRC Inspection Report 05000440/2017009 and Preliminary White Finding

ML17200C945
Person / Time
Site:	Perry
Issue date:	07/14/2017
From:	Hamilton D FirstEnergy Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-17-216 IR 2017009
Download: ML17200C945 (6)

See also: IR 05000440/2017009

Text

FENOCŽ FirstEnergy

Nuclear Operating

Company David B. Hamilton

Vice President

-July 14, 2017 L-17-216

A ITN: Document

Control Center U.S. Nuclear Regulatory

Commission

Washington,

DC 20555-0001

SUBJECT:

Perry Nuclear Power Plant Docket No. 50-440, License No. NPF-58 Perry Nuclear Power Plant P.O. Box 97 10 Center Road Perry, Ohio 44081 440-280-5382

Response

to NRC Inspection

Report 05000440/2017009

and Preliminary

White Finding On June 5, 2017, the Nuclear Regulatory

Commission

(NRC) issued Inspection

Report 05000440/2017009

and a Preliminary

White Finding to the Perry Nuclear Power Plant. This Inspection

Report contained

a Preliminary

White Finding and Apparent

Violation

• 05000440/2017009-01

"Unsuitable

Application

of Surge Suppression

Diodes in Standby Diesel Generator

Control Power Circuitry."

In a letter dated June 14, 2017, the FirstEnergy

Nuclear Operating

Company (FENOC) notified

the NRC of our choice to submit a written response

to the Inspection

Report. Attached

is FENOC's response,

which adds some clarification

to the initial apparent

violation.

We have reviewed

the preliminary

white finding and we believe the description

of the performance

deficiency

does not comport with the root cause and it does not accurately

characterize

the issue. The attachment

provides

detail of the disputed

language.

We respectfully

request your consideration

of this information

prior to issuing the final violation.

There are no regulatory

commitments

contained

in this letter. If there are any questions

or if additional

information

is required,

please contact Mr. Nicola Conicella, Regulatory

Compliance,

at (440) 280-5415.

Sincerely,

David Hamilton

Vice President

Perry Nuclear Power Plant L-17-216

Page 2 Attachments

Response

to Apparent

Violation 05000440/2017009-01

"Unsuitable

Application

of Surge Suppression

Diodes in Standby Diesel Generator

Control Power Circuitry"

cc: NRG Branch Chief -Jamnes Cameron NRG Project Manager -Kimberly

Green NRG Regional

Administrator

-Cynthia D Pederson

NRG Director

of Reactor Projects

-Patrick L. Louden NRG Resident

Inspectors

Attachment

l-17-216

Page 1of4 Violation

Details Inspection

Report 05000440/2017009,

dated June 5, 2017, contained

the following

Preliminary

White Finding for the Perry Nuclear Power Plant (PNPP): Preliminary

White. The inspectors

identified

a finding preliminarily

determined

to be of low to moderate

safety significance

(White),

and an associated

apparent

violation

of Title 10 of the Code of Federal Regulations

(10 CFR) 50, Criterion

Ill, "Design Control,"

for the licensee's

failure to implement

measures

for the selection

and review for suitability

of application

of voltage suppression

diodes installed

in the control circuitry

for the Division

2 Standby Diesel Generator,

which was a component

subject to the requirements

of 10 CFR Part 50, Appendix

B. Specifically,

Engineering

Change Package 04-0049 failed to consider

the effects of a shorted diode on the control circuitry

for the Division

2 Standby Diesel Generator,

and instead,

introduced

new components

(diodes)

into the control circuitry

that resulted

in the eventual

failure of this safety-related

equipment.

This rendered

the standby diesel generator

inoperable

and unable to start for longer than its technical

specification

allowed outage time, which was a violation

of Technical

Specification

3.8.1, "AC Sources-Operating."

The licensee

documented

the issue in CR 2016-13183,

and subsequently

replaced

the failed component

and then modified

circuitry

to remove the replacement

diode and the remaining

diodes from similar components.

, The inspectors

determined

that the licensee's

failure to evaluate

the effects of voltage suppression

diode failure on the Standby Diesel Generator

control circuit was contrary

to the requirements

of 10 CFR Part 50, Appendix

B, Criterion

Ill and a performance

deficiency

which was within the licensee's

ability to foresee and prevent.

The inspectors

determined

that the performance

deficiency

was of more than minor significance

because it was associated

with the design control attribute

of the mitigating

systems cornerstone

and adversely

affected

the cornerstone

objective

to ensure the availability,

reliability,

and capability

of systems that respond to initiating

events to prevent undesirable

consequences

(i.e., core damage).

Specifically,

the design of the Division

2 Standby Diesel Generator

control circuit resulted

in the inoperability

and unavailability

of the Division

2 Standby Diesel Generator

from April 2, 2015, to November

8, 2016, when the failed diode was replaced.

A Significance

and Enforcement

Review Panel, using IMC 0609, Appendix

A, "Significance

Determination

Process for Findings

At-Power,"

dated June 19, 2012, preliminarily

determined

the finding to be of low-to-moderate

safety significance.

The inspectors

did not identify

any cross-cutting

aspects associated

with this finding because the condition

had existed si.nce at least 2007, when the diodes were originally

installed

in the DC control power circuits,

and therefore,

was not indicative

of current plant performance.

(Section

40A2.1) Response

The FirstEnergy

Nuclear Operating

Company (FENOC) does not agree with the performance

deficiency

as described.

FENOC asserts that the design was adequate

Attachment

L-17-216

Page 2of4 and appropriate

for use in the control circuit and without the manufacturing

defect would have functioned

as designed.

The Apparent

Violation

as described

has these main points that FENOC does not agree* with: * Installation

of surge suppression

diodes in the SDG control circuit was not evaluated

and, without mitigation

for failure,

was not appropriate

for the SDG control power circuit.

• Installation

of surge suppression

diodes provided

no safety benefit to the SDG control system. * The diode failure rendered

the standby diesel generator

inoperable

and unable to start for longer than its technical

specification

allowed outage time. Details Installation

of surge suppression

diodes in the SDG control circuit was not evaluated

and, without mitigation

for failure,

was not appropriate

for the SDG control power circuit.

• The effects of a diode failure were considered

as an aggregate

evaluation

of parts rather than component

by component

individual

evaluations.

The Updated Safety Analysis

Report (USAR) does not discuss the reliability

of SDG components

at the level that the change was being made. For the SDG engine and generator,

the USAR only discusses

malfunction

of the SDG as a unit with the result being the loss of one divisional

SDG. There are no failure modes and effects analysis

in the USAR for subcomponents

of the diesel generator

itself, the speed control system or its controls.

• No new failure modes were introduced

by the addition

of surge suppression

diodes as addressed

in NEI 96-07 "Guidelines

For 10 CFR 50.59 Evaluations"

section 4.3.6. The 50.59 Evaluation

for ECP 04-0049 states "Reliability

of the new components

has been based on industry

experience

and experience

at other nuclear facilities

.... [operating]

experience

was reviewed

through [Institute

of Nuclear Power Operations]

and no adverse trends were noted for the new components."

• The diodes were installed

consistent

with IEEE recommended

practice

for Powering

and Grounding

Electronic

Equipment

Section 10.4.4.1,

Contact Suppression,

IEEE Std. 1100-2005,

which states, this is standard

practice

in any industrial

control system. It also states that the first choice in a DC circuit is a flyback diode for voltage suppression.

The IEEE standard

does not provide mitigation

strategies

for

failure.

Installation

of surge suppression

diodes provided

no safety benefit to the SDG control system. * The use of suppression

diodes does provide a safety benefit in that the voltage suppression

helps to minimize

arcing and degradation

of contacts

that interrupt

current to the relays (reference

the Root Cause Report for CR 2016-14456).

It was later determined

that the diodes could be removed without significantly

impacting

components

in the Division

1 and 2 125 VDC control circuitry

and the increased

risk could be managed through preventative

maintenance

(PM) frequency

controls.

Attachment

L-17-216

Page 3of4 The diode failure rendered

the standby diesel generator

inoperable

and unable to start for longer than its technical

specification

allowed outage time. * Continuity

testing in May 2016 demonstrated

that the diode was not shorted,

therefore,

had not failed upon de-energization

in April 2015. The apparent

violation

stated that the test conducted

in May 2016 was not a valid test. Although

continuity

testing would not have detected

an internal

manufacturing

defect, it was an adequate

test to determine

if the diode was shorted,

which would have precluded

the SDG from performing

its intended

function.

• The root cause concluded

the cause to be a defective

diode (cracked

die). It is not clear at what point in time the degradation

of the diode would have progressed

to the point of failing upon re-energization.

With a cracked die in the diode, there are multiple

stressors

that could have affected

it, including

temperature

changes.

Therefore,

there is no firm evidence

demonstrating

that the diode was failed in May 2016. As such, with the absence of firm evidence

otherwise,

it should be assumed that the diode failed at the time of discovery.

Conclusion

FENOC asserts the following:

• Installation

of surge suppression

diodes in the SDG control circuit was appropriately

evaluated

and was appropriate

for the SDG control power circuit.

• Installation

of surge suppression

diodes provided

a safety benefit to the SDG control system. * The diode failure did not render the SDG inoperable

and unable to start for longer than its technical

specification

allowed outage time. The root cause determined

the failure to be a manufacturing

defect in the specific

diode that was installed

in the Division

2 SDG that was to protect the components

within the SDG start circuitry.

This was supported

by independent

laboratory

diode testing and a 1 OCFR Part 21 notification,

by the vendor who supplied

the diodes, of a manufacturing

defect internal

to the diode with the same date code as the installed

diode. The supplier

of the diodes used non-conservative

acceptance

criteria

for initial diode leakage tests during their dedication

process.

As a result, the potential

exists that a diode was supplied

from the manufacturer

in a degraded

condition

and was not detected

during commercial

grade dedication

process.

In the absence of a manufacturing

defect, the diodes were sufficient

for the application.

FENOC agrees that loss of control power to the Division

2 SDG should not have occurred

and has taken corrective

actions to prevent recurrence.

Individual

components,

such as diodes, purchased

under our Quality Assurance

(QA) program are assumed to be reliable.

In the NRC's Enforcement

Policy, section 3.5, the NRC may refrain from issuing enforcement

action for violations

resulting

from matters not within a licensee's

control,

such as equipment

failures

that were not avoidable

by reasonable

licensee

QA measures

or management

controls.

FENOC believes

this to be the case in that this manufacturing

defect was not detected

through the supplier's

commercial

grade dedication

process.

Hence, FENOC believes

NRC discretion

is warranted based

on our understanding

of the deficiency

and the root cause conclusions.

FENOC respectfully

Attachment

L-17-216

Page 4 of 4 requests

that this performance

deficiency

be re-evaluated

and discretion

applied as per the NRC's Enforcement

Policy section 3.5. i