05000336/FIN-2018010-01

Finding

Title

Over-Duty Breakers on Safety-Related Buses on Unit 2

Description

The team identified a finding of very low safety significance (Green) and an associated non-cited violation (NCV) of Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix B, Criterion III, Design Control. Specifically, Dominion incorrectly concluded that the 480V safety-related breakers were conforming to the plants licensing basis following their identification that the calculated short circuit fault current exceeded the breaker rating. Dominions evaluation failed to take into consideration that non-class 1E loads fed from safety-related buses must be isolated from the class 1E system by fully qualified safety-related isolation devices (breakers). Dominions design basis requires that a circuit fault on the non-class 1E side of the isolation device shall not cause the loss of the associated safety-related system

01
Site:	Millstone
Report	IR 05000336/2018010 Section 1R21
Date counted	Jun 30, 2018 (2018Q2)
Type:	NCV: Green
cornerstone	Mitigating Systems
Identified by:	NRC identified
Inspection Procedure:	IP 71111.21M
Inspectors (proximate)	K Mangan M Patel J Brand J Rady C Lally C Baron J Nicely M Gray
Violation of:	10 CFR 50 Appendix B 10 CFR 50 Appendix B Criterion III, Design Control
CCA	P.2, Evaluation
INPO aspect	PI.2
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v • d • e

Finding - Millstone - IR 05000336/2018010

1(0)1(0)2(0)3(1)4(0)5(0)6(0)10(5)11(1)301(0)403(1)410(1)501(0)

IR 05000336/2018010: 1 3 4 2 5

Finding List (Millstone) @ 2018Q2

CCA Matrix: 2018Q2

	Q	CCA	Title
05000336/FIN-2017007-01	2017Q3		Failure to Replace Auxiliary Feedwater Solenoid Valves within the Required Frequency
05000336/FIN-2017003-01	2017Q3	H.12	Inadequate Procedure Results in Inadvertent Lowering of Spent Fuel Pool Level
05000423/FIN-2017004-01	2017Q4	H.5	Failure to Maintain RCS Pressure during Solid Plant Cooldown
05000336/FIN-2018010-03	2018Q2	P.5	Failure to Correct Part 21 Power Supply Defects
05000336/FIN-2018010-01	2018Q2	P.2	Over-Duty Breakers on Safety-Related Buses on Unit 2
05000423/FIN-2018010-02	2018Q2	P.1	Over-Duty Breakers on Safety-Related Bus 34C on Unit 3
05000336/FIN-2018010-04	2018Q2	P.3	Flood Seals Not Installed in Unit 2 A EDG and Auxiliary Building Penetrations
05000423/FIN-2018010-05	2018Q2		Inadequate Test Control of ECCS Valve Interlocks
05000336/FIN-2018410-01	2018Q2	H.1	Security

Self-Identified List (Millstone)

[Millstone Findings full list]

05000336/FIN-2018010-01

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