TAA - Overview and Reactivity abnormalities

Question 1

State the 7 reactivity anomolies identified in the UFSAR.

Answer 1

1. Uncontrolled CEA w/d from subcritical
2. Uncontrolled CEA w/d at power
3. Single full strength CEA drop
4. Startup of of inactive RCP
5. Inadvertent Deboration
6. Inadvertent Loading of a Fuel Assy into the Improper position.
7. CEA Ejection

Question 2

Identify the limiting fault event with respect to Reactivity and Power distribution anomolies

Answer 2

CEA Ejection.

CEDM housings are capable of withstanding throughout their design life all normal operating loads including SS and Transient operating conditions specified for the Rx Vessel.

Question 3

State the UFSAR accident analysis requirements.

Answer 3

• Demonstrates adequate protection of the public health and safety from exposure to any undue radiological risk.
• Specifies acceptance criteria for various abnormal occurrences and events
• To define the requirements for PVGS licensing documents: Design Specs, Tech Specs, Emergency Procedures

Question 4

State the PVGS safety limits and their purpose.

Answer 4

Ensure that specified acceptable fuel design limits (SAFDLs) are not exceeded during steady state operation, normal operational transients, and Anticipated Operational Occurrences (AOOs).

Accomplished by having a DNB design basis, (95/95 DNB criterion) that DNB will not occur and by requiring that fuel centerline temperature stays below the melting temperature.

Reactor Core SLs (Modes 1-2)

1. DNBR ≥ 1.34
2. Peak fuel centerline temp < 5080°F (↓ by 58°F per 10,000 MWD/MTU)
3. RCS Pressure SL (Modes 1-5) ≤ 2750 psia

Protects RCS integrity against over-pressurization. In the event of fuel cladding failure, FPs are released into the RCS. RCS then serves as the primary barrier in preventing the release of FPs into the atmosphere.

Question 5

Define AOO(Anticipated Operational Occurance)

Answer 5

AOO: Event or set of conditions that is expected to occur at leastonce during the operating lifetime of a facility.

Question 6

Define limiting fault:

Answer 6

Limiting Fault: Faults that are NOT excpected to occur but are postulated because of their consequences and potential for the release of radiation

Question 7

Define Limiting Event:

Answer 7

• Worst case potential set of conditions in a particular event category, and is what helps determine plant design, set-points, operability requirements, etc.
• Event or events in a category of events that would require LCOs, procedures, plant design, etc. to minimize the consequences to the health and safety of nuclear workers and the public.

Question 8

Define single failure criteria:

Answer 8

AN occurrence which results in the loss of capability of a component to perform its intended safety functions.

Multiple failures resulting from a single occurence are considered to be a single failure.

Question 9

How long do you have to take actions on the slip or drop of a CEA from full power per the UFSAR?

Answer 9

900 seconds or 15 minutes to take actions per the AOP. Commence a downpower within in 10 minutes meets the requriements of the UFSAR.

Question 10

How is the operator alerted to an inadvertent dilution event while shutdown?

Answer 10

BDAS channels operable will alert the CR staff on a rising neutron flux. Startup flux channels are required to notify by 15 minutes before criticality in Mode 3-5 and 30 minutes in Mode 6