Text

Examination Report Letter No. 50-297/OL-25-02, North Carolina State University
	ML25036A360
Person / Time
Site:	North Carolina State University
Issue date:	06/03/2025
From:	Tony Brown; NRC/NRR/DANU/UNPO
To:	Hawari A; North Carolina State University
References
	50-297/25-002 50-297/OL-25
	Download: ML25036A360 (1)
	v • d • e

Dr. Ayman I. Hawari, Director Nuclear Reactor Program Department of Nuclear Engineering North Carolina State University Campus Box 7909 2500 Stinson Drive Raleigh, NC 27695-7909

SUBJECT:

EXAMINATION REPORT NO. 50-297/OL-25-02, NORTH CAROLINA STATE UNIVERSITY

Dear Dr. Hawari:

During the week of April 21, 2025, the U.S. Nuclear Regulatory Commission (NRC) administered an operator licensing examination at your North Carolina State University research reactor. The examination was conducted according to NUREG-1478, "Operator Licensing Examiner Standards for Research and Test Reactors," Revision 2. Examination questions and preliminary findings were discussed with those members of your staff identified in the enclosed report at the conclusion of the examination.

In accordance with Title 10 of the Code of Federal Regulations, Section 2.390, a copy of this letter and the enclosures will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records component of NRC's Agencywide Documents Access and Management System (ADAMS). ADAMS is accessible from the NRC website at http://www.nrc.gov/reading-rm/adams.html. The NRC is forwarding the individual grades to you in a separate letter which will not be released publicly. Should you have any questions concerning this examination, please contact Amy Beasten at (301) 415-8341 or via email at Amy.Beasten@nrc.gov.

Sincerely, Tony Brown, Chief Non-Power Production and Utilization Facility Oversight Branch Division of Advanced Reactors and Non-Power Production and Utilization Facilities Office of Nuclear Reactor Regulation Docket No. 50-297

Enclosures:

1. Examination Report No. 50-297/OL-25-02

2. Written examination cc: w/enclosures to GovDelivery Subscribers June 3, 2025 Signed by Brown, Tony on 06/03/25

ML25036A360 NRR-079 OFFICE NRR/DANU/UNPO/CE NRR/DANU/UNPO/OLA NRR/DANU/UNPO/BC NAME ABeasten NJones TBrown DATE 6/3/2025 6/3/2025 6/3/2025 U. S. NUCLEAR REGULATORY COMMISSION OPERATOR LICENSING INITIAL EXAMINATION REPORT REPORT NO.:

50-297/25-02 FACILITY DOCKET NO.:

50-297 FACILITY LICENSE NO.:

R-120 FACILITY:

North Carolina State University PULSTAR EXAMINATION DATES:

Week of April 21, 2025 SUBMITTED BY:

SUMMARY

During the week of April 21, 2025, the NRC administered operator licensing examinations to two Reactor Operator (RO) candidates. All candidates passed all applicable portions of the operating and written tests and examinations.

REPORT DETAILS 1.

Examiner:

Amy E. Beasten, PhD, Chief Examiner, NRC 2.

Results:

RO PASS/FAIL SRO PASS/FAIL TOTAL PASS/FAIL Written 2/0 N/A 2/0 Operating Tests 2/0 N/A 2/0 Overall 2/0 N/A 2/0 3.

Exit Meeting:

Amy E. Beasten, PhD, Chief Examiner, NRC Margaret N. Goodwin, Reactor Engineer, NRC Austin Wells, Manager of Engineering and Operations, North Carolina State University Zachary Boulton, Senior Reactor Operator, Engineer, North Carolina State University Anna Deak, Reactor Health Physicist, North Carolina State University Prior to administration of the written examination, based on facility comments, adjustments were accepted. Comments provided corrections and additional clarity to questions/answers and identified where changes were appropriate based on current facility conditions.

Upon completion of all operator licensing examinations, the NRC examiner met with facility staff representatives to discuss the results. At the conclusion of the meeting, the NRC examiner thanked the facility for their support in the administration of the examination.

5/28/2025 Name, Chief Examiner Date North Carolina State University Operator Licensing Examination Week of April 21, 2025

U. S. NUCLEAR REGULATORY COMMISSION NON-POWER REACTOR LICENSE EXAMINATION FACILITY:

North Carolina State University REACTOR TYPE:

PULSTAR DATE ADMINISTERED:

04/23/2025 CANDIDATE:

INSTRUCTIONS TO CANDIDATE:

Answers are to be written on the Answer sheet provided. Attach all Answer sheets to the examination. Point values are indicated in parentheses for each question. A 70% in each category and a 70% overall are required to pass the examination. Examinations will be picked up three (3) hours after the examination starts.

CATEGORY VALUE

% OF TOTAL CANDIDATE'S SCORE

% OF CATEGORY VALUE CATEGORY 20.00 33.0 A. REACTOR THEORY, THERMODYNAMICS, AND FACILITY OPERATING CHARACTERISTICS 20.00 33.0 B. NORMAL AND EMERGENCY OPERATING PROCEDURES AND RADIOLOGICAL CONTROLS 20.00 33.0 C. FACILITY AND RADIATION MONITORING SYSTEMS 60.00 TOTALS FINAL GRADE All work done on this examination is my own. I have neither given nor received aid.

Candidate's Signature

NRC RULES AND GUIDELINES FOR LICENSE EXAMINATIONS During the administration of this examination the following rules apply:

1.

Cheating on the examination means an automatic denial of your application and could result in more severe penalties.

2.

After the examination has been completed, you must sign the statement on the cover sheet indicating that the work is your own and you have neither received nor given assistance in completing the examination. This must be done after you complete the examination.

3.

Restroom trips are to be limited and only one candidate at a time may leave. You must avoid all contacts with anyone outside the examination room to avoid even the appearance or possibility of cheating.

4.

Use black ink or dark pencil only to facilitate legible reproductions.

5.

Print your name in the blank provided in the upper right-hand corner of the examination cover sheet and each Answer sheet.

6.

Mark your Answers on the Answer sheet provided. USE ONLY THE PAPER PROVIDED AND DO NOT WRITE ON THE BACK SIDE OF THE PAGE.

7.

The point value for each question is indicated in [brackets] after the question.

8.

If the intent of a question is unclear, ask questions of the examiner only.

9.

When turning in your examination, assemble the completed examination with examination questions, examination aids and Answer sheets. In addition turn in all scrap paper.

10.

Ensure all information you wish to have evaluated as part of your Answer is on your Answer sheet. Scrap paper will be disposed of immediately following the examination.

11.

To pass the examination you must achieve a grade of 70 percent or greater in each category.

12.

There is a time limit of three (3) hours for completion of the examination.

Category A: Reactor Theory, Thermodynamics, & Facility Operating Characteristics A N S W E R S H E E T Multiple Choice (Circle or X your choice)

If you change your answer, write your selection in the blank.

A01 a b c d ___

A02 a b c d ___

A03 a b c d ___

A04 a b c d ___

A05 a b c d ___

A06 a b c d ___

A07 a b c d ___

A08 a b c d ___

A09 a b c d ___

A10 a b c d ___

A11 a _____ b _____ c _____ d _____ (0.25 each)

A12 a b c d ___

A13 a b c d ___

A14 a b c d ___

A15 a b c d ___

A16 a b c d ___

A17 a b c d ___

A18 a b c d ___

A19 a b c d ___

A20 a b c d ___

(***** END OF CATEGORY A *****)

Category B: Normal/Emergency Operating Procedures and Radiological Controls A N S W E R S H E E T Multiple Choice (Circle or X your choice)

If you change your answer, write your selection in the blank.

B01 a b c d ___

B02 a b c d ___

B03 a ______________ b ______________ c ______________ d ______________

B04 a b c d ___

B05 a b c d ___

B06 a b c d ___

B07 a b c d ___

B08 a b c d ___

B09 a b c d ___

B10 a b c d ___

B11 a b c d ___

B12 a b c d ___

B13 a b c d ___

B14 a b c d ___

B15 a b c d ___

B16 a b c d ___

B17 a b c d ___

B18 a b c d ___

B19 a b c d ___

B20 a b c d ___

(***** END OF CATEGORY B *****)

Category C: Facility and Radiation Monitoring Systems A N S W E R S H E E T Multiple Choice (Circle or X your choice)

If you change your answer, write your selection in the blank.

C01 a b c d ___

C02 a b c d ___

C03 a b c d ___

C04 a b c d ___

C05 a b c d ___

C06 a b c d ___

C07 a b c d ___

C08 a b c d ___

C09 a b c d ___

C10 a b c d ___

C11 a b c d ___

C12 a b c d ___

C13 a b c d ___

C14 a b c d ___

C15 a b c d ___

C16 a b c d ___

C17 a b c d ___

C18 a b c d ___

C19 a b c d ___

C20 a b c d ___

(***** END OF CATEGORY C *****)

(********** END OF EXAMINATION **********)

EQUATION SHEET

=

+

DR - Rem, Ci - curies, E - Mev, R - feet 1 Curie = 3.7 x 1010 dis/sec 1 kg = 2.21 lb 1 Horsepower = 2.54 x 103 BTU/hr 1 Mw = 3.41 x 106 BTU/hr 1 BTU = 778 ft-lb

°F = 9/5 °C + 32 1 gal (H2O) 8 lb

°C = 5/9 (°F - 32) cP = 1.0 BTU/hr/lb/°F cp = 1 cal/sec/gm/°C

2 2

max

P 1

sec 1.0

eff

T UA H

m T

c m

Q P

sec 10 1

4

2 1

1 1

2 1

eff eff K

CR K

CR

eff SUR 06 26

te P

P 0

eff K

S S

SCR

1

2 2

1 1

CR CR

0 1

P P

1 2

1 1

CR CR K

M eff

)

(

0 10 t

SUR P

P 2

1 1

1 eff eff K

K M

eff eff K

K SDM

1 eff eff K

K 1

2 2

1 1

d DR d

DR

t e

DR DR

0

1 2

2 2

Peak Peak

2 6

R n

E Ci DR 2

1 1

2 eff eff eff eff K

K K

K

693

.0 2

1 T

Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics QUESTION A.01

[1.0 point]

Which ONE of the following statements best describes the relationship between neutron energy and the microscopic cross section of absorption in the low energy (1/v) region?

a. As the neutron energy increases, the cross section increases exponentially.

b. As the neutron energy decreases, the cross section decreases linearly.

c.

As the neutron energy decreases, the cross section increases linearly.

d. As the neutron energy increases, the cross section decreases exponentially.

QUESTION A.02

[1.0 point]

Which ONE of the following statements regarding delayed neutrons is NOT correct?

a. Delayed neutrons are less likely to undergo thermal leakage than prompt neutrons

b. Delayed neutrons are born at lower energies than prompt neutrons.

c.

Delayed neutrons are less likely to undergo resonance capture than prompt neutrons.

d. Delayed neutrons are more effective at causing fission than prompt neutrons.

QUESTION A.03

[1.0 point]

Which ONE of the following statements best describes Ficks Law of Diffusion?

a. The number of neutrons per unit area at any given time can be calculated by determining the number of neutrons that are being removed and added at any given time.

b.

Natural convection in a reactor allows for the proper cooling by ensuring the heated water rises and is replaced by cooler water to flow up the fuel.

c.

If the density of neutrons is higher in one part of a reactor than another, there is a net flow of neutrons into the region of lower neutron density.

d.

Radioactive particles will always travel in a straight line until hitting and interacting with another particle or incident atom.

Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics QUESTION A.04

[1.0 point]

During the initial rise to power, the nuclear instruments show that when Keff is 0.85, the count rate is 1280 cps. Once reactivity has been added, what count rate would correspond with a Keff of 0.95?

a.

4530 cps b.

3840 cps c.

3310 cps d.

2270 cps QUESTION A.05

[1.0 point]

Which ONE of the following BEST describes Departure from Nucleate Boiling?

a.

The point at which the water surrounding the fuel begins to rabidly boil.

b.

The point at which bubbles no longer collapse after leaving the surface of the fuel.

c.

The point at which bubbles formed from boiling coalesce into a vapor covering the fuel.

d.

The point at which a vapor film forms over the entirety of the fuel region.

QUESTION A.06

[1.0 point]

When calculating core excess reactivity at NCSU, which ONE of the following does NOT influence excess reactivity?

a.

Fuel burnup b.

Pool temperature c.

Xenon presence d.

Control Rod Height

Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics QUESTION A.07

[1.0 point]

Which ONE of the following statements BEST describes the Liquid-Drop Model of a nucleus?

a.

The energy required to displace all the subatomic particles is similar to the energy required to disperse all the water molecules in a drop of water.

b.

The density of a nucleus remains constant regardless of atomic number, much like a drop of water has a constant density regardless of how large it gets.

c.

The size on an atoms nucleus compared to the size of the whole atom is similar to the size of a drop of water compared to an ocean.

d.

The travel path of an atom in a reactor when traced, matches the flow of a single drop of water.

QUESTION A.08

[1.0 point]

If the Startup Rate (SUR)of a reactor is 2.6 decades per minute, how long will it take for reactor power to increase from 1.8 kW to 225 kW?

a.

5.7 minutes b.

3.9 minutes c.

2.2 minutes d.

0.8 minutes QUESTION A.09

[1.0 point]

Which ONE of the following statements best describes Internal Conversion?

a.

An orbital election is absorbed by the nucleus, converts a proton into a neutron and a neutrino, and leaves the nucleus in an excited state.

b.

A neutron in the nucleus changes to a proton, emitting an electron.

c.

The excitation energy of a nucleus is used to eject an orbital election.

d.

A neutron is ejected from the nucleus of a metastable isotope.

Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics QUESTION A.10

[1.0 point]

An experimenter inserts an experiment into the core, and the count rate increases to 185 cps from 60 cps. Given the initial k-effective of the reactor is 0.924, what is the worth of the experiment?

a.

= + 0.057 b.

= - 0.057 c.

= - 0.176 d.

= + 0.176 QUESTION A.11

[1.0 point]

Match the neutron interaction in Column A with the reaction type (symbol) in Column B.

Options in Column B may be used once, more than once, or not at all.

Column A a.

Elastic Scattering

b. Radiative Capture

c. Inelastic Scattering

d. Charged Particle Reaction Column B 1.

(n, n) 2.

(n, n) 3.

(n, p) 4.

(n, )

QUESTION A.12

[1.0 point]

Which ONE of the following nuclear reactions is NOT an example of an exothermic reaction?

a.

The neutron activation and decay of Nitrogen-16.

b.

The fission of Uranium-235.

c.

An elastic scattering collision between a neutron and oxygen atom.

d.

The inelastic scattering of a neutron and a water molecule.

Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics QUESTION A.13

[1.0 point]

The instantaneous energy released from fission is equal to ______________________.

a.

the difference in binding energy between the initial neutron and U-235 atom and the fission products.

b.

the difference in thermal energy of the incident nucleus and the neutron.

c.

the average energy of all prompt neutrons generated per fission.

d.

the mass of released neutrons multiplied by the speed of light.

QUESTION A.14

[1.0 point]

What is the remaining power following the prompt drop in the reactor power when a rod worth of 0.893 k/k is rapidly inserted into a critical reactor? Assume eff = 0.0065 a.

0.78%

b.

1.37%

c.

8.92%

d.

13.7%

QUESTION A.15

[1.0 point]

When describing the forces incident on a ground state nucleus, the attractive __________

forces are greater than the repulsive ____________ forces.

a.

kinetic; potential b.

binding; separating c.

nuclear; electrostatic d.

magnetic; nuclear QUESTION A.16

[1.0 point]

Which ONE of the following best describes when a reactor is critical?

a.

keff = 1; = 0 b.

keff > 1; < 0 c.

keff = 1; > 0 d.

keff < 1; = 0

Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics QUESTION A.17

[1.0 point]

Given a reactor period of 39 seconds, how long will it take for reactor power to triple?

a.

13.0 seconds b.

26.4 seconds c.

42.8 seconds d.

57.3 seconds QUESTION A.18

[1.0 point]

The rate at which power decreases after a scram is limited by ____________________:

a.

the fission product decay of the longest-lived delayed neutron precursor.

b.

the time spent at power above the point of adding heat.

c.

the presence of a graphite reflector.

d.

the peak fuel temperature.

QUESTION A.19

[1.0 point]

Which ONE of the following statements best describes the relationship between the flux and fuel temperature profiles in the core?

a.

Fuel temperature and neutron flux are uniform throughout the core, except in the vicinity of the control rods, where both decrease.

b.

Fuel temperature and core flux are both greatest in the center of the core.

c.

Fuel temperature and neutron flux are both greatest at the top of the active fuel region, regardless of location within the core.

d.

Fuel temperature is greatest at the center of the core, but neutron flux is greatest at the periphery of the core away from the control rods.

Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics QUESTION A.20

[1.0 point]

Which ONE of the following is a characteristic of an effective core reflector?

a.

A high scattering to absorption cross section ratio.

b.

A low resistance to radiation damage.

c.

A small crystal expansion structure.

d.

A low thermal conductivity.

(***** END OF CATEGORY A *****)

Category B: Normal/Emergency Operating Procedures and Radiological Controls QUESTION B.01

[1.0 point]

In accordance with the NCSU PULSTAR Emergency Plan, which ONE of the following tasks is NOT the responsibility of the Emergency Team?

a.

Install emergency systems and structures.

b.

Assess equipment damage.

c.

Determine and report radiological conditions.

d.

Communicate with other organizations as necessary.

QUESTION B.02

[1.0 point]

In accordance with OP-301, Fuel Handling, which ONE of the following statements BEST describes the method used to determine the reactivity worth of a fuel assembly?

a.

Using computer software such as MCNP or SCALE ORIGEN to model the reactivity worth of the individual fuel assembly.

b.

Measuring the core excess reactivity with and without the fuel assembly and then calculating the difference.

c.

Determining the critical control rod heights with and without the fuel assembly in the core and calculating the difference in reactivity.

d.

Calculating the shutdown margin with and without the fuel assembly in the core and determining the difference.

Category B: Normal/Emergency Operating Procedures and Radiological Controls QUESTION B.03

[1.0 point]

Match the following experiment descriptions in Column A with their respective types in Column B. Options may be used once, multiple times, or not at all.

Column A a.

A second set of gold foils irradiated in the previously established in-core location.

b.

An experiment comprised of 20%

Thorium-232 by weight dispersed in aluminum.

c.

An experiment designed to float within the reactor tank and monitor water temperature at various depths and distances from the core.

d.

Irradiation of a sample containing 10 mg of TNT in a beam tube weighed down with lead pellets.

Column B a.

Fueled b.

Secured c.

Tried d.

Moveable QUESTION B.04

[1.0 point]

When performing a reactor startup, the previous Count Rate is 873 cps, which correlates to a Keff of 0.899. What Count Rate would result in a new Keff of 0.965?

a.

1217 b.

1807 c.

2519 d.

3064 QUESTION B.05

[1.0 point]

In accordance with OP-103, Reactor Operation, which ONE of the following events requires notification of the Designated Senior Reactor Operator?

a.

Power fluctuations due to an unknown cause.

b.

When the reactor has reached the desired power level.

c.

Recording fuel movements in the Logbook.

d.

Calculation of the shutdown margin that is greater than 550 pcm.

Category B: Normal/Emergency Operating Procedures and Radiological Controls QUESTION B.06

[1.0 point]

In accordance with OP-104, Reactor Experiments, which ONE of the following experiments would require reactor operation with facility ventilation in confinement mode?

a.

An experiment containing 25µg of U-235.

b.

An experiment designed to move a N-16 detector around the reactor top.

c.

An experiment containing moon rocks for fission track dating.

d.

A triple encapsulated experiment designed to stay in the core until the structural integrity of the inner container fails.

QUESTION B.07

[1.0 point]

In accordance with OP-101, Reactor Startup and Shutdown, which ONE of the following conditions is NOT required to perform a Key-on Startup?

a.

No maintenance on Technical Specification Reactor Safety Systems has been performed.

b.

The Reactor Keyswitch has been turned off for less than 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

c.

There have been no new experiments added since the last reactor startup.

d.

The Confinement/Evacuation System was operated satisfactorily less than 7 days ago.

QUESTION B.08

[1.0 point]

In accordance with OP-101, Reactor Startup and Shutdown, when performing a Fast Recovery Reactor Startup, which ONE of the following conditions would indicate that the reactor is still substantially subcritical after initial control rod motion has stopped?

a.

Reactor power slowly begins to increase and continues to increase at an exceedingly slow rate.

b.

Reactor power begins to increase slowly then begins to rapidly decrease.

c.

There is no discernible change in reactor power with initial control rod withdrawal.

d.

Reactor power begins to increase and then starts to slowly decrease.

Category B: Normal/Emergency Operating Procedures and Radiological Controls QUESTION B.09

[1.0 point]

In accordance with HP 5, Access Control and Training, which ONE of the following people would NOT be considered an Occupational Worker?

a.

A visiting researcher who is using one of the beam lines for their work.

b.

A visiting researcher participating in a short facility tour where the planned exposure is less than 2mrem.

c.

A visiting researcher conducting an experiment requiring multiple visits over a two-month period.

d.

A visiting repair technician who needs to fix some wiring issues in a High Radiation Area.

QUESTION B.10

[1.0 point]

In accordance with NCSU Technical Specifications, which ONE of the following best describes a Reactor Operator?

a.

An individual who has been certified to operate within the facility under indirect supervision.

b.

An individual who has been properly trained and tested and been granted permission to help train others in manipulating facility controls.

c.

An individual who is licensed under 10 CFR Part 55 to manipulate the controls in the facility.

d.

An individual who has been sufficiently trained to operate the reactor without supervision.

QUESTION B.11

[1.0 point]

Which ONE of the following considerations was NOT used when determining the Limiting Safety System Setting (LSSS) of 250 kW for Natural Convective Flow?

a.

The prevention of bulk boiling in any channel.

b.

The prevention of fuel cladding damage.

c.

Minimizing the generation of steam bubbles in the pool.

d.

Minimizing the Nitrogen-16 dose at the pool surface.

Category B: Normal/Emergency Operating Procedures and Radiological Controls QUESTION B.12

[1.0 point]

In accordance with OP-105, Response to SCRAMS, Alarms, and Abnormal Conditions, which ONE of the following scenarios would require an immediate reactor SCRAM?

a.

Low Reactor Building Differential Pressure b.

Abnormal Coolant Temperature c.

Imaging Facility Entry Alarm d.

Low Natural Gas Pressure QUESTION B.13

[1.0 point]

In accordance with OP-202, Service Water, which ONE of the following parameters is important when starting the Service Water System?

a.

Density b.

Resistivity c.

Temperature d.

Radioactivity QUESTION B.14

[1.0 point]

In accordance with OP-104 Reactor Experiments, when removing a sample from its irradiation location, which ONE of the following is recorded?

a.

Sample storage location.

b.

Person who removed the sample.

c.

Radiation dose rate at 30 cm.

d.

Experimenter who requested the irradiation.

QUESTION B.15

[1.0 point]

In accordance with OP-103 Reactor Operation, which ONE of the following evolutions does NOT require supervision of the Designated Senior Reactor Operator?

a.

Relocation of an in-core experiment worth $0.50.

b.

Operation when the Shutdown Margin is in between 400 pcm and 500 pcm.

c.

Initial approach to criticality.

d.

Return to full power after an unplanned significant power reduction.

Category B: Normal/Emergency Operating Procedures and Radiological Controls QUESTION B.16

[1.0 point]

In accordance with HP 1, Radiation Protection Program, which ONE of the following actions is required when leaving a Contaminated Area?

a.

Whole body monitoring for at least two minutes.

b.

General body survey using a Geiger Muller type frisker.

c.

Nasal swab along with hand swipes.

d.

Contamination check of the hands and feet using a standard Hand and Foot Monitor.

QUESTION B.17

[1.0 point]

Which ONE of the following scenarios would NOT be classified as a Notification of Unusual Event?

a.

A dose rate of 15 mrem in a 24-hour period at the site boundary.

b.

A verified bomb threat to the facility.

c.

An armed attack on the facility resulting in hostages.

d.

A hurricane that reverses the negative pressure differential of the facility.

QUESTION B.18

[1.0 point]

A special exposure is planned that requires an operator to perform work in the Primary Piping Vault while the reactor is operating at 1 MW. They receive a dose of 250 mrem in 80 minutes. How should the Primary Piping Vault be posted?

a.

No posting required b.

A Radiation Area c.

A High Radiation Area d.

A Very High Radiation Area

Category B: Normal/Emergency Operating Procedures and Radiological Controls QUESTION B.19

[1.0 point]

In accordance with the Technical Specifications, which ONE of the following scenarios does NOT describe a Secured Reactor?

a.

Sufficient fuel has been removed from the core and placed in storage such that even with all the control rods fully withdrawn, criticality cannot be achieved.

b.

The reactor console is off with the shim rod decoupled from the rod drive and removed from the reactor pool to support maintenance on the pneumatic system.

c.

Five fuel bundles have been removed from the core and the rest are being inspected.

d.

An experiment worth 800 pcm is being placed in a Dry Exposure Port.

QUESTION B.20

[1.0 point]

If the dose rate of the primary cooling piping is 8rem/hr on contact due to Nitrogen-16, how long does the water need to stay in the delay tanks in order to decay to a dose rate of 5mrem/hr? Assuming the half-life of N-16 is 7 seconds.

a.

25 seconds b.

50 seconds c.

75 seconds d.

100 seconds

(***** END OF CATEGORY B *****)

Category C: Facility and Radiation Monitoring Systems QUESTION C.01

[1.0 point]

Which ONE of the following statements best describes the design of the irradiated fuel storage pits?

a.

The pits are designed to prevent inadvertent criticality by the misplacement of two additional fuel assemblies next to each other in a tightly packed configuration.

b.

The pits are designed in such a way that they can hold up to 15 assemblies and will not achieve criticality in the event that another fuel assembly is accidently placed in one that is full.

c.

The pits are designed to hold 13 fuel assemblies spaced in such a way as to prevent the multiplication factor from exceeding 0.8.

d.

The pits are designed to keep the fuel assemblies as cool and unreactive as possible.

QUESTION C.02

[1.0 point]

In accordance with OP-201, Primary Demineralizer, which ONE of the following actions could result in damage to the resin?

a.

Not placing a rag over the vent when opening valves PD-4, PD-8, and PD-10.

b.

Allowing flow rates in extreme excess of 20 GPM through the system.

c.

Draining and filling the system only as necessary.

d.

Allowing the resin to dry completely prior to restart if the system needs to be drained.

QUESTION C.03

[1.0 point]

Which ONE of the following statements best describes why previous graphite reflectors were replaced with beryllium?

a.

The beryllium reflectors were added to help act as a reflector and a better shield against gamma radiation than the graphite.

b.

The graphite reflectors had begun to degrade and release small amounts of graphite into the water.

c.

The beryllium reflectors are able to react with the startup source decreasing the amount of plutonium needed to reach the required startup count rate.

d.

The beryllium reflectors added greater excess reactivity to the core than the graphite reflectors.

Category C: Facility and Radiation Monitoring Systems QUESTION C.04

[1.0 point]

Which ONE of the following nuclear instruments would be the first to detect a leak coming from a fuel pin?

a.

Linear Channel b.

Safety Chanel c.

Log-N Channel d.

The N-16 Channel QUESTION C.05

[1.0 point]

Which ONE of the following is NOT a characteristic of the PULSTAR UO2 Zircaloy clad fuel?

a.

Low thermal conductivity.

b.

High fission product retention.

c.

Low probability of fast non-leakage.

d.

Doppler broadening of the microscopic absorption cross section.

QUESTION C.06

[1.0 point]

Which ONE of the following statements BEST describes the difference between the flow of primary cooling water in forced convection versus natural convection?

a.

In forced convection flow, cooled water flows up away from the core to mix with the bulk coolant, then down through the core into the outlet pipe. In natural convection flow, the water flows up through the core from the outlet plenum.

b.

In both forced and natural convection, cooled water from the outlet plenum flows up through the core and down around the core to the core plenum.

c.

In forced convection flow, the cooled water flows up away from the core to mix with the bulk coolant, then through the upper core plenum and down around the pool liner. In natural convection, water flows up from the outlet plenum away from the core then down through the core.

d.

In forced convection flow, the cooled water flows from the outlet plenum up through the core and then down around the core. In natural convection flow, the water flows down through the core then up and around the core.

Category C: Facility and Radiation Monitoring Systems QUESTION C.07

[1.0 point]

Which ONE of the following scenarios would require insertion of the Shim Rod into the core?

a.

Calculation of the shutdown margin based on previously determined reactivity worths.

b.

Determination of fuel bundle reactivity worths.

c.

Reactor power measuring channel calibrations.

d.

Determination of control rod reactivity worths.

QUESTION C.08

[1.0 point]

Which ONE of the following statements regarding the PULSTAR control rods is true?

a.

Individual and ganged rod withdrawal speed is limited to ensuring the reactivity insertion rate is less than 100 pcm/second (for safety rods and regulating rod only).

b.

The control rod drive motors vary the ganged control rod speeds to automatically slow rod withdrawal rates as criticality is approached.

c.

When the rods are ganged, a Reverse will drive all control rods, including the shim rod, down.

d.

A Ground Fault Detection SCRAM signal causes all control rods, including the Shim rod, to scram.

QUESTION C.09

[1.0 point]

Which ONE of the following reactor power measuring channels is NOT affected if the control rods are not banked?

a.

Log-N Channel b.

Startup Channel c.

Safety Channel d.

N-16 Channel

Category C: Facility and Radiation Monitoring Systems QUESTION C.10

[1.0 point]

Which ONE of the following actions automatically occurs when there is a loss of commercial power to the reactor facility?

a.

The stack monitor sampling pump will continue to draw air in for emergency monitoring.

b.

The control room and reactor bay lights will continue to operate normally.

c.

Facility ventilation switches to Confinement mode.

d.

The control console will lose power.

QUESTION C.11

[1.0 point]

Which ONE of the following features is used to minimize the generation of radioactive isotopes within the Pneumatic Transfer System when not in use?

a.

A nitrogen purge throughout the system.

b.

Utilization of the blowers to generate a vacuum within the system.

c.

A steady flow of carbon dioxide (CO2) within the system.

d.

Periodic cleaning to ensure the complete removal of radioactive material.

QUESTION C.12

[1.0 point]

Which ONE of the following conditions would result in a reactor SCRAM without an annunciator indication?

a.

Low Primary Flow SCRAM.

b.

Ground Fault Detection SCRAM.

c.

Manual SCRAM.

d.

High Power SCRAM on the Safety Channel QUESTION C.13

[1.0 point]

Which ONE of the following conditions would cause the Secondary Coolant Pump to automatically stop?

a.

T6 is reading 80o F.

b.

Resistivity dropping to 1 Mcm.

c.

Primary flow rate reading 480 gpm.

d.

A loss of the primary cooling pump.

Category C: Facility and Radiation Monitoring Systems QUESTION C.14

[1.0 point]

Which ONE of the following statements best describes the function of the N-16 detector as it relates to providing a readout of Reactor Power?

a.

It is a neutron sensitive NaI scintillator detector that emits a light that is linearly proportional to reactor power.

b.

It is a gamma sensitive gas filled ion chamber that detects Nitrogen-16 via its decay and provides a signal that is linearly proportional to reactor power.

c.

It is a neutron sensitive gas filled compensated ion chamber that detects Nitrogen-16 through the neutron activation of water and is logarithmically proportional to reactor power.

d.

It is a gamma sensitive gas filled uncompensated ion chamber designed to only detect the gammas from Nitrogen-16 and provides a signal that is exponentially proportional to reactor power.

QUESTION C.15

[1.0 point]

In accordance with OP-103 Reactor Operation, which ONE of the following conditions would indicate that reactor power is GREATER than 1 MW?

a.

The Safety Channel is reading 1MW while the N-16 Detector is reading 900 kW.

b.

Control rods are banked at approximately 10% lower than the estimated critical rod heights at 1 MW.

c.

The shutdown margin was calculated to be 150 pcm greater than it was the previous day.

d.

The temperature difference between T5 and T6 is 18° C.

QUESTION C.16

[1.0 point]

Which ONE of the following statement best describes how the confinement system mitigates the release of radioactive material?

a.

The confinement system stops almost all airflow into the reactor bay and only allows air to exit the bay after it has passed through multiple filters.

b.

The system maintains a negative pressure in the bay with respect to the outside only when in confinement mode.

c.

The confinement system is designed to run all air coming into and exiting the reactor bay through filters to ensure its as clean as possible.

d.

The confinement system shuts down all airflow into and out of the facility to prevent the release of radioactive material.

Category C: Facility and Radiation Monitoring Systems QUESTION C.17

[1.0 point]

In accordance with NCSU Technical Specifications, which ONE of the following would prevent reactor startup?

a.

A DEP being placed near-core with an experiment worth $0.75.

b.

The Nitrogen-16 detector being tagged Out-of-Service.

c.

The shim rod stuck in the full in position.

d.

A startup count rate of 1.8 cps.

QUESTION C.18

[1.0 point]

Which ONE of the following statements best describe the purpose of the delay tanks in the primary system?

a.

The delay tanks are used to hold the primary water and provide a point to drain the system if necessary to support repairs to the reactor pool.

b.

The delay tanks are used to hold primary water long enough to allow the Nitrogen-16 to decay, lowering the radiation dose above the reactor.

c.

The delay tanks are used to hold the primary water in place long enough to allow debris to settle, thus removing it from the water going back into the tank.

d.

The delay tanks provide initial cooling of the primary water prior to entry into the heat exchanger to ensure adequate cooling.

QUESTION C.19

[1.0 point]

Which ONE of the following statements best describes the use of the Automatic Control System?

a.

Automatic control of the Regulating Rod cannot be used when the Gang Drive switch is engaged.

b.

Automatic rod control will work for any demand power starting from any power level.

c.

Automatic rod control works no matter how far the Regulating Rod is withdrawn or inserted.

d.

Automatic rod control can only be used in the 1 MW power range.

Category C: Facility and Radiation Monitoring Systems QUESTION C.20

[1.0 point]

Which ONE of the following statements best describes the operation of the secondary cooling system?

a.

The secondary system monitors the flow rate of the primary system and varies its speed to always be greater than the primary to ensure a greater pressure in the event of potential mixing.

b.

The secondary cooling system monitors the temperature of the primary water and varies the speed of the cooling tower fan to provide optimal cooling.

c.

The secondary cooling system monitors the temperature of the primary water and varies the flow rate of the secondary cooling water to optimize cooling.

d.

The secondary cooling system will turn the pump on and off depending on the temperature of the primary water.

(***** END OF CATEGORY C *****)

(********** END OF EXAMINATION **********)

Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics A.01 Answer:

c

Reference:

DOE Fundamentals Handbook, Volume 1, Module 2, p. 9 A.02 Answer:

a

Reference:

NCSU PULSTAR Reactor Theory Manual 2.3 A.03 Answer:

c

Reference:

Lamarsh, Introduction to Nuclear Engineering, p. 191 A.04 Answer:

b

Reference:

CR1*(1-Keff1) = CR2*(1-Keff2)

CR2 =

CR1 (1 keff1)

(1 Keff2)

CR2 =

Lamarsh, Introduction to Nuclear Engineering, pages 16, 44, & 45

Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics A.10 Answer:

a

Reference:

CR1 / CR2 = (1 - keff2) / (1 - keff1) 60 / 185 = (1 - keff2) / (1 - 0.924) 0.324 = (1 - keff2) / 0.076 0.0246 = (1 - keff2)

Therefore keff2 = 0.975

= (keff2 - keff1) / (keff2

keff1)

= (0.975 - 0.924) / (0.975

0.924)

Reference:

Burn, Introduction to Nuclear Reactor Operations, p. 9-12 A.20 Answer:

a

Reference:

DOE Fundamentals Handbook, Vol. 2, Module 4, p. 25

(***** END OF CATEGORY A *****)

Category B: Normal/Emergency Operating Procedures and Radiological Controls B.01 Answer:

d

Reference:

NCSU PULSTAR Technical Specifications 1.2.19

80 60

= 1.3333 250 1.3333 = 187.5 /

10CFR20 definition of a High Radiation Area is greater than 100mrem/hr at 30cm from the source B.19 Answer:

d

Reference:

NCSU PULSTAR Technical Specifications 1.2.22

Category B: Normal/Emergency Operating Procedures and Radiological Controls B.20 Answer:

c

Reference:

= 0 0 8

5

=

ln (2)

= 7 5 = 8000 ln(2) 7

ln 5

8000 = ln(2) 7

ln(2) = ln 5

8000 7

=

7 ln (

5 8000 )

ln (2)

= 74.5 rounded to 75 seconds

(***** END OF CATEGORY B *****)

NCSU Operating Procedure 105 Responses to SCRAMS, Alarms, and Abnormal Conditions 2.3s

NCSU PULSTAR Safety Analysis Report 5.3

(***** END OF CATEGORY C *****)

(********** END OF EXAMINATION **********)

ML25036A360

Text

SUBJECT:

Dear Dr. Hawari:

Enclosures:

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