05000334/LER-2017-002

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LER-2017-002, 1 OF 4
Beaver Valley Power Station Unit Number 1
Event date: 07-19-2017
Report date: 09-13-2017
Reporting criterion: 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications

10 CFR 50.73(a)(2)(vii)(A), Common Cause Inoperability

10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor
Initial Reporting
ENS 52571 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition, 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor
3342017002R00 - NRC Website
LER 17-002-00 for Beaver Valley Power Station, Unit No. 1 Regarding Inadequate Emergency Diesel Generator (EOG) Tornado Missile Protection Identified Due to Non-conforming Design Conditions
ML17261A193
Person / Time
Site: Beaver Valley FirstEnergy icon.png
Issue date: 09/13/2017
From: Bologna R D
FirstEnergy Nuclear Operating Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
L-17-290
Download: ML17261A193 (5)


comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

05000- Beaver Valley Power Station Unit Number 1 334 Energy Industry Identification System (EIIS) codes identified in the in the text as [XX].

CONDITIONS PRIOR TO OCCURENCE

Beaver Valley Power Station Unit 1 (BV-1) was in Mode 1 at 100% Power There were no Structures, Systems, or Components (SSCs) that were inoperable at the start of the event that contributed to the event.

DESCRIPTION OF EVENT

In order to address the concerns outlined in NRC Regulatory Issue Summary (RIS) 2015-06 "TORNADO MISSILE PROTECTION", evaluations of tornado missile vulnerabilities and their potential impact on Technical Specification (TS) plant equipment were conducted. This particular evaluation concluded that the following Structures, Systems, and Components (SSCs) are potentially vulnerable to tornado generated missiles.

(BV-1) is potentially vulnerable to tornado generated missiles. A tornado could generate missiles capable of striking the EDG engine exhaust piping potentially crimping it and resulting in reduced engine exhaust flow capacity. In the worst case (based on multiple missile strikes), both BV-1 EDGs could be rendered inoperable.

On July 19, 2017, both BV-1 TS required EDGs were declared inoperable and Enforcement Guidance Memorandum (EGM) 15-002 Rev 1 "Enforcement Discretion for Tornado-Generated Missile Protection Noncompliance," was applied.

Compensatory measures were implemented within the time allowed by the applicable Limiting Condition(s) for Operation and the EDGs were then declared operable but nonconforming.

This issue is reportable under 10 CFR 50.72(b)(3)(v) for a loss of safety function. However, enforcement discretion is being applied. As stated in EGM 15-002, Rev. 1, after the initial tornado missile 10 CFR 50.72 notification, the NRC staff will exercise enforcement discretion for any subsequent tornado missile 10 CFR 50.72 notifications provided that the associated initial compensatory measures are, or soon (not to exceed the expiration of the time mandated by the corresponding LCO) will be, in place and the licensee reports any additional tornado missile non-compliances with 10 CFR 50.73 "License Event Report System".

The initial tornado missile non-conformances were previously reported in EN 52571 by FirstEnergy Nuclear Operating Company (FENOC) in a 10 CFR 50.72 notification to the NRC on February 23, 2017.

The potential tornado missile vulnerabilities for the BV-1 EDGs engine exhaust piping (discussed above) are being addressed in accordance with EGM 15-002 Rev 1 and DSS-ISG-2016-01 (NRC enforcement discretion and interim guidance documents). Immediate compensatory measures were taken to reduce the likelihood and mitigate the potential consequences of tornado generated missiles.

comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

05000- NUMBER NO.

.002 00 Beaver Valley Power Station Unit Number 1 334 2017 -

CAUSE OF EVENT

This condition is part of the original BV-1 design and has existed since the initial construction and licensing of the plant.

BV-1 received its operating license in 1976. The design of the BV-1, as described in the Updated Final Safety Analysis Report (UFSAR), does not address the fact that the exhaust piping is not fully protected against multiple tornado missiles.

However, the BV-1 UFSAR does address that missile protection is provided for the EDG buildings. The EDG engine exhaust piping is protected up to the discharge tee at the end of the piping. The exhaust piping discharge tee is protected on two sides and the top from tornado missiles but is open on the remaining two sides for the exhaust discharge. It could not be determined if the existing configuration of the EDG engine exhaust piping was evaluated during the original design and licensing process, or if this condition was considered acceptable due to the low likelihood of damage to the engine exhaust piping from tornado generated missiles.

Based on the above, the apparent cause of BV-1 EDG engine exhaust piping not being fully tornado missile protected was a lack of clarity during the plant's original design and licensing. This led to an inadequate understanding of the tornado missile protection regulatory requirements.

ANALYSIS OF EVENT

There were no actual consequences resulting from the nonconforming condition. A tornado that could produce the design basis missiles is highly unlikely. There are no actual safety consequences impacting plant safety since BV-1 has not experienced any onsite tornado missile event in at least the past three years. The probability of tornado missiles causing multiple EDG engine exhaust piping to become inoperable is very low.

The plant risk associated with the tornado missile exposure to BV-1 for the EDG exhaust piping is considered to be very low. This is based on the observation that the probability of tornado-generated missiles hitting the maximum (bounding) unprotected target area is significantly smaller than the baseline Core Damage Frequencies of the effective BV-1 Probabilistic Risk Assessment (PRA) model.

Based on the above, the safety significance of the defined licensing basis nonconforming conditions identified by engineering walk downs conducted in accordance with RIS 2015-06 is very low.

This condition is being reported in accordance with the following 10 CFR 50.73 criteria:

  • 10 CFR 50.73(a)(2)(i)(B) for any condition which was prohibited by the plant's Technical Specifications. [The BV-1 EDGs potentially being inoperable for longer than TS 3.8.1 required completion times.]
  • 10 CFR 50173(a)(2)(v)(A) for any condition that could have prevented the fulfillment of the safety function of systems that are needed to shut down the reactor and maintain it in a safe shut down condition. [Both BV-1 EDGs potentially being inoperable concurrently].
  • 10 CFR 50.73(a)(2)(vii)(A) for any event where a single cause or condition caused at least two independent trains to become inoperable in a single system designed to shut down the reactor and maintain it in a safe shut down condition.

[Both trains of BV-1 EDGs potentially being inoperable due to same causes (i.e., tornado missiles).

comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

CORRECTIVE ACTIONS:

1. Revised BV-1 / BV-2 operating manual procedure 1/20M-53C.4A.75.1 "Acts of Nature — Severe Weather" to specifically mention the BV-1 EDG engine exhaust piping as being vulnerable to tornado generated missiles, and provide guidance for plant operators to check these as one of the first areas for damage following a tornado or when identifying potential missiles around the site before a possible tornado.

2. The nonconformance of the BV-1 EDG engine exhaust piping may be addressed through physical plant modifications, industry approved risk evaluation, or another method in compliance with the plant's licensing basis.

The Corrective Actions listed above will be tracked by applicable condition reports and/ or Notifications associated with this event.

PREVIOUS SIMILAR EVENTS

A review of previous BVPS LERs in the past three years was conducted for issues related to removing/maintaining tornado missile barriers during plant operation. The following LERs were determined to be similar to this event:

BV-1 and BV-2 LER 2014-005-00 "Containment equipment hatch missile shield removal inadvertently results in exceeding Technical Specification 3.6.1 required completion times".

BV-1 and BV-2 LER 2017-001-00, "Beaver Valley Power Station Unit 1 and Unit 2 Inadequate Tornado Missile Protection Identified Due to Non-Conforming Design Conditions".

CR 2017-07550