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ILOT > Primary Containment - 1.0 > Flashcards

Primary Containment - 1.0 Flashcards

1
Q

What is the drywell design criteria?

A
  1. DESIGN TEMPERATURE LIMIT: 340F (Based on ability of SRV solenoids AND torus to drywell vacuum breakers to function due to small line break – not MSIVs or rx to torus vacuum breaker valves)
  2. Pressure: 62 psig – to maintain less than 65 for PCPL
  3. DW Temp maintained < 135F to ensure temp does not exceed 340F during a LOCA.
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2
Q

What is the TORUS design criteria?

A
  1. Temperature: 310F (T sat for 62 psig)
  2. Pressure: 62psig internal
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3
Q

What is the DW & Torus external pressure limit?

A

3 psid - Assumes inadvertent spray of DW. W/ two RHR loops active and 1 vac vkr fail to open.

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4
Q

What is the DBA for 135°F in drywell?

A

Small steam line break releasing superheated steam to the drywell.

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5
Q

What is the DBA for the maximum pressure in drywell?

A

Instantaneous circumferential double ended break of the reactor recirc pump suction piping.

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6
Q

What is the purpose of Primary Containment isolation?

A

Provides the capability to rapidly isolate all penetrations.

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7
Q

Can the drywell be flooded?

A

Yes. Get resume ready.

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8
Q

What are the Seismic criteria?

A

Seismic Category 1
* Safe Shutdown Earthquake (SSE) Maximum earthquake the plant could see and still shutdown. (.2g)
* Operating Bases Earthquake (OBE) Maximum earthquake the plant is expected to see. (.1g)

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9
Q

What is the TS definition of primary containment?

A

SPLASH
- Suppression chamber is in compliance with TS.
- All Penetrations required to be closed during accident:
* Closed (by at least one manual valve, blind flange, or deactivated auto valve secured in its closed position, except as provided in Table 3.6.3-1)
* Capable of being closed by OPERABLE PCIS valve.
- Primary containment leakage in compliance within TS limits.
- Sealing mechanism associated with each penetration operable.
- Equipment Hatches closed and sealed.

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10
Q

Describe the operation of the vacuum breakers for TORUS to Drywell.

A

Torus to Drywell (8 with setpoint of .2 psid) (Operate with PCIG)
a) When the steam in the drywell from a LOCA starts to condense, it could draw a vacuum inside the drywell and exceed the external design pressure.
* Fail Open – over (internal) pressurize due to loss of suppression capability (steam is not forced through the water of the suppression pool)
* Fail Closed – under pressure due to condensing steam. Pressure cannot be equalized with torus; as a result the design external pressure of the dry may be exceeded.

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11
Q

Describe the operation of the vacuum breakers for RB to TORUS.

A

Reactor Building to Torus (2 with setpoint of .25 psid) (Normally op with IA, backup with PCIG)
b) Cooling of the torus can cause a negative pressure to develop and cause the external pressure of the torus and/or the drywell to be exceeded.
* Open – Loss of primary containment integrity. Unmonitored release. (Unlikely due to in series valves)
* Closed – Potential (unlikely) under pressure of containment. (Exceed external pressure of Torus)

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12
Q

Who can approve DW entry?

A
  1. All entries – SM and RPM
  2. Any entry in mode 1 – Plant Manager
  3. Entry when inerted or at power (>15%) – Site VP.
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13
Q

What are the leakage limits based on?

A
  1. Limit leakage <10CFR100 limit during and following the DBA to values less than leakage rates which would result in off-site doses equal to:
    • 25 Rem whole body does
    • 300 Rem thyroid dose
      This limit is based on an assumed leakage of .5% total volume over a 24 hour period with the drywell at 62 psig.
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14
Q

What are the barriers for fission product release?

A
  1. Fuel – Oxide layer tends to retain fission products.
  2. Cladding – If intact, prevent fission product gas escape to the moderator/coolant.
  3. Reactor Coolant System – The vessel and primary system maintain fission products in a closed cycle if they escape from fuel rods such that all releases from this system are controlled.
  4. Primary Containment – Contains fission products in the event of primary system failure.
  5. Secondary Containment – Provides for an elevated release in the event of a primary containment failure.
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15
Q

What does a Hi DW pressure initiate?

A

DW Pressure Hi/Hi - Setpoint: 1.68 psig initiates the following:

  1. Reactor Scram
  2. PCIS / NSSSS Isolations
  3. FRVS Initiation
  4. TIP Withdraw
  5. Core Spray Initiation
  6. RHR (LPCI) Initiation
  7. HPCI Initiation
  8. EDG Start
  9. TACS Isolation
  10. LOCA sequencer initiation
  11. ADS Input
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16
Q

What are the alarm setpoints for DW pressure Hi/Lo.

A

1.5 psig / .1 psig

17
Q

What are the TORUS level Hi/Lo setpoints?

A

SP Level Hi/Lo

  1. Hi 78.5”
  2. Pre-High: 78”
  3. Lo: 75”
  4. Lo-Lo: 65”
18
Q

What are the TORUS High temps?

A

95, 105, 110, and 120F (alarm only)

ILOT (93 decks)

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