VLS(2) - Containment Hydrogen Control

3 Subsystems of VLS

Concentration Monitoring

Recombination (PARs)

Ignition

PARs

(Passive Autocatalytic Recombiners)

Hydrogen Limit design basis?

Within 4%

*The catalytic reaction produces A LOT of heat which promotes natural vapor circulation within containment

Severe Accident Guidelines

Hydrogen concentration if 100% cladding oxidation?

Within 10%

EITHER igniter group can satisfy this design limit

Severe Accident Guidelines

WITHOUT igniters available

Hydrogen concentration if 75% cladding oxidation?

Within 13%

This concentration is based solely on Containment Volume

Hydrogen production methods?

Cladding oxidation (LOCA)

Normal RCS content

Corrosion product

Radiolysis of water

CET temperature indication of need for igniters?

1200F

Manual ignition guided by E-Network

Hydrogen sensing circuity and methods of visual

3 Non-Safety sensors, Alarm at 3%

2 display units outside Containment

PLS indication in Control Room and RSR

Ignition

Power Supply

Actuation Methods/Differences

Group 1: EDS3-EA-14C (Each Group 33 igniters)

Group 2: EDS2-EA-14B

PLS Click: Can ignite Groups individually

DAS Switches (2/2): ALL

*There is a test panel outside of Control Room that can energize igniters individually (66 switches)

Loss of Power

Igniter Availability

EDS batteries will provide 2hrs of full loads as designed

AFTER the 2hrs there is guidance to shed other loads, allowing the igniters to be available for an additional 4hrs

SO: WITH Operator Action Igniters are available for 6 total hours following normal loss of EDS Charger Power (SBO)

TRM 3.6.2 Hydrogen Igniters

Applicability

MODES 1 and 2

MODE 5: Open

MODE 6: UppInternals in place

MODE 6: Cavity <23’ above flange

TRM 3.6.2 Hydrogen Igniters

TRS 3.6.2.1 Temperature Requirement?

Surface Temperature >/=1700F

TRM 3.6.2 Hydrogen Igniters

Bases

When should maintenance be performed?

MODES 3 and 4

(Outside TRM applicability)