ML24169A116
| ML24169A116 | |
| Person / Time | |
|---|---|
| Site: | Armed Forces Radiobiology Research Institute |
| Issue date: | 02/06/2025 |
| From: | Michael Brown NRC/NRR/DANU/UNPO |
| To: | Smolinski A US Dept of Defense, Armed Forces Radiobiology Research Institute |
| References | |
| 50-170/OL-25-01 OL-25-01 | |
| Download: ML24169A116 (1) | |
Text
Andrew Smolinski, Reactor Facility Director Chief, Reactor Division Radiation Sciences Department Armed Forces Radiobiology Research Institute 4301 Jones Bridge Road, Building 42 Bethesda, MD 20889-5648
SUBJECT:
EXAMINATION REPORT NO. 50-170/OL-25-01, ARMED FORCES RADIOBIOLOGY RESEARCH INSTITUTE
Dear Andrew Smolinski:
During the week of January 20, 2025, the U.S. Nuclear Regulatory Commission (NRC) administered an operator licensing examination at your Armed Forces Radiobiology Research Institute 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 301-415-8347 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. 50-170
Enclosures:
- 1. Examination Report No. 50-170/OL-25-01
- 2. Written examination cc: w/enclosures to GovDelivery Subscribers February 6, 2025 Signed by Brown, Tony on 02/06/25
ML24169A116 NRR-079 OFFICE NRR/DANU/UNPO/CE NRR/DANU/UNPO/OLA NRR/DANU/UNPO/BC NAME ABeasten NJones TBrown DATE 2/6/2025 2/6/2025 2/6/2025 U. S. NUCLEAR REGULATORY COMMISSION OPERATOR LICENSING INITIAL EXAMINATION REPORT REPORT NO.:
50-170/OL 25-01 FACILITY DOCKET NO.:
50-170 FACILITY LICENSE NO.:
R-120 FACILITY:
Armed Forces Radiobiology Research Institute EXAMINATION DATES:
Week of January 20, 2025 SUBMITTED BY:
SUMMARY
During the week of January 20, 2025, operator licensing examinations were administered to two Senior Reactor Operator-Instant (SRO-I) candidates. All candidates passed all applicable portions of the written and operating examinations.
REPORT DETAILS 1.
Examiner:
Amy E. Beasten, PhD, Chief Examiner, NRC 2.
Results:
RO PASS/FAIL SRO PASS/FAIL TOTAL PASS/FAIL Written 0/0 2/0 2/0 Operating Tests 0/0 2/0 2/0 Overall 0/0 2/0 2/0 3.
Exit Meeting:
Amy E. Beasten, PhD, Chief Examiner, NRC Maggie Goodwin, Reactor Engineer, NRC Andrew Cook, Head, Radiation Sciences Department, AFRRI Andrew Smolinski, Reactor Facility Director, AFRRI Benjamin Knibbe, Reactor Operations Supervisor, AFRRI Addison Guynn, Senior Reactor Operator, AFRRI Prior to administration of the written exam, 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 examiners met with facility staff representatives to discuss the results and observations. At the conclusion of the meeting, the NRC examiners thanked the facility for their support in the administration of the examination.
1/30/2025 Amy E. Beasten, Chief Examiner Date Armed Forces Radiobiology Research Institute Research Reactor Operator Licensing Examination Week of January 20, 2025 U. S. NUCLEAR REGULATORY COMMISSION NON-POWER REACTOR LICENSE EXAMINATION FACILITY:
AFRRI REACTOR TYPE:
TRIGA DATE ADMINISTERED:
January 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 ___
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: Plant 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
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 2
1 1
2 eff eff eff eff K
K K
K
693
.0 2
1 T
eff eff K
K 1
2 2
2 2
1 1
d DR d
DR
t e
DR DR
0
1 2
1 2
2 2
Peak Peak
2 6
R n
E Ci DR
Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics QUESTION A.01
[1.0 point]
What is the amount of positive reactivity (%k/k) that is added to a subcritical reactor when Keff is increased from 0.750 to 0.925?
a.
12.1% k/k b.
17.5% k/k c.
25.2% k/k d.
33.3% k/k QUESTION A.02
[1.0 point, 0.25 each]
For each scenario in Column A, identify the direction in Column B that control rods would need to be moved at AFRRI to maintain constant reactor power. Answers in Column B may be used once, more than once, or not at all.
Column A a.
Withdrawal of neutron source b.
Fuel temperature decrease c.
Buildup of Ar-41 d.
Burnup of U-235 Column B
- 1. Insert
- 2. Withdraw
- 3. No movement QUESTION A.03
[1.0 point]
Which ONE of the following factors in the six-factor formula is NOT affected by the enrichment of U-235 in the fuel?
a.
Fast non-leakage probability (Lf) b.
Resonance escape probability (p) c.
Reproduction factor ()
d.
Thermal utilization factor (f)
Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics QUESTION A.04
[1.0 point]
Approximately _____ MeV is released instantaneously per fission of U-235.
a.
250 b.
200 c.
190 d.
157 QUESTION A.05
[1.0 point]
The moderator temperature coefficient for a reactor is -0.00095 k/k/oF. What is the total reactivity change caused by a temperature decrease of 15oF?
a.
+ 0.14250 b.
- 0.14250 c.
+ 0.01425 d.
- 0.01425 QUESTION A.06
[1.0 point]
All of the following statements regarding Xe-135 are true EXCEPT:
a.
Following a reactor shutdown, Xe-135 concentrations will increase due to the decay of I-135.
b.
Xe-135 is produced directly from fission and is removed from the core by neutron absorption.
c.
After a power increase, Xe-135 concentrations will initially decrease due to increased burnout and will peak at a higher equilibrium value.
d.
After a power decrease, Xe-135 concentrations will initially decrease due to burnout and will peak at a lower equilibrium value.
Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics QUESTION A.07
[1.0 point]
Which ONE of the following statements best describes the effective multiplication factor, keff?
a.
The ratio of neutrons produced by fission in one generation to the number of neutrons lost through absorption and leakage in the preceding generation.
b.
The ratio of neutrons produced by fission in one generation to the number of thermal neutrons lost through leakage in the preceding generation.
c.
The ratio of neutrons produced by fission in one generation to the number of neutrons lost through absorption in the preceding generation.
d.
The ratio of neutrons produced by fast fission in one generation to the number of neutrons lost through leakage in the preceding generation.
QUESTION A.08
[1.0 point]
Which ONE of the following statements best describes the function of a reflector?
- a. Reduce the power output of a reactor by slowing fission neutrons to thermal energies.
- b. Provide additional radiological shielding to protect personnel working near the reactor.
c.
Reduce the ratio of peak flux to the flux at the edge of the core fuel area.
- d. Increase the ratio of flux at the edge of the core fuel area to peak flux to shorten irradiation times for periphery or external experiments.
QUESTION A.09
[1.0 point]
Which ONE of the following statements best describes the effect of the negative moderator temperature coefficient of reactivity?
a.
Increases in moderator temperature result in an increase in moderator density, which causes more moderation. As a result, leakage decreases and keff increases.
b.
Increases in moderator temperature result in an increase in moderator density, which causes more moderation. As a result, the resonance escape probability increases and keff decreases.
c.
Increases in moderator temperature result in a decrease in moderator density, which causes less moderation. As a result, leakage increases and keff decreases.
d.
Increases in moderator temperature result in an increase in moderator density, which causes more moderation. As a result, leakage decreases and keff increases.
Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics QUESTION A.10
[1.0 point]
The current count rate is 450 cps. An experimenter inserts an experiment into the core and the count rate increases to 700 cps. If the initial Keff was 0.875, what is the worth of the experiment?
a.
+ 0.0554 b.
- 0.0554 c.
- 0.0978 d.
+ 0.0978 QUESTION A.11
[1.0 point]
Which ONE of the following statements best describes radiative capture?
a.
A neutron interacts with a nucleus to form a compound nucleus, which returns to ground sate by gamma emission (n, ).
b.
A neutron is absorbed by a nucleus, leading to the immediate emission of a charged particle like an alpha particle or proton (n, p).
c.
A neutron is absorbed by a nucleus, which splits into two smaller nuclei, releasing additional neutrons and energy.
d.
A neutron is absorbed by a nucleus to form a compound nucleus, which emits a lower kinetic energy neutron, and returns to ground state by gamma emission (n, n).
QUESTION A.12
[1.0 point]
Which ONE of the following statements best describes the macroscopic cross-section ()?
a.
The probability of a given reaction occurring per unit length of travel of the neutron, with units of cm2.
b.
The probability of a given reaction occurring between a neutron and a nucleus, with units of cm2.
c.
The probability of a given reaction occurring between a neutron and a nucleus, with units of cm-1.
d.
The probability of a given reaction occurring per unit length of travel of the neutron, with units of cm-1.
Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics QUESTION A.13
[1.0 point]
Which ONE of the following statements best describes the significance of delayed neutrons in reactor operation?
a.
Delayed neutrons ensure that there is a sufficient neutron population to provide visible indication of neutron level during start-up and shutdown.
b.
Delayed neutrons ensure there is a sufficient neutron population to overcome the effects of fission product poisoning following a shutdown.
c.
Delayed neutrons are emitted during fission and are essential to achieve and maintain reactor criticality.
d.
Delayed neutrons are important in lengthening the neutron generation time to ensure proper control of the reactor during power increases.
QUESTION A.14
[1.0 point]
Elastic scattering is defined as:
a.
The process in which a neutron collides with a nucleus causing the nucleus to split into smaller particles.
b.
The process in which a neutron strikes a ground state nucleus, the neutron is re-emitted and the nucleus remains in the ground state.
c.
The process in which a neutron strikes a ground state nucleus to form a compound nucleus.
A neutron of lower kinetic energy is emitted, leaving the nucleus in an excited state, which decays by gamma emission.
d.
The process in which a neutron strikes a ground state nucleus to form a compound nucleus, with the neutron being re-emitted.
QUESTION A.15
[1.0 point]
Which ONE of the following factors in the six-factor formula accounts for the probability that a fast neutron will be slowed to thermal energies without being absorbed in the fuel?
- a. Reproduction factor ()
- b. Fast fission factor ()
- c. Thermal utilization factor (f) d.
Resonance escape probability (p)
Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics QUESTION A.16
[1.0 point]
Given the following values, determine the status of the reactor in terms of criticality.
Fast Fission Factor = 1.02 Thermal Utilization Factor = 0.71 Fast Non-Leakage Probability = 0.97 Thermal Non-Leakage Probability = 0.99 Reproduction Factor = 1.57 Resonance Escape Probability = 0.92 a.
The reactor is critical.
b.
The reactor is subcritical.
c.
The reactor is supercritical.
d.
The reactor is prompt critical.
QUESTION A.17
[1.0 point]
Which ONE of the following statements is best describes the behavior of the microscopic cross-section of fission (f) for U-235?
a.
The values are highest for the thermal neutron energy range.
b.
It has resonance peaks which expand as fuel temperature increases.
c.
It remains constant for all neutron energies.
d.
It increases linearly with increasing neutron energy.
QUESTION A.18
[1.0 point]
While bringing the reactor critical, which ONE of the following describes how a subcritical reactor responds to equal insertions of positive reactivity?
a.
Each reactivity insertion results in a smaller increase in neutron flux resulting in a shorter time to stabilize.
b.
Each reactivity insertion results in a larger increase in neutron flux resulting in a shorter time to stabilize.
c.
Each reactivity insertion results in a smaller increase in neutron flux resulting in a shorter time to stabilize.
d.
Each reactivity insertion results in a larger increase in neutron flux resulting in a longer time to stabilize.
Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics QUESTION A.19
[1.0 point]
Which ONE of the following describes when a reactor is supercritical?
a.
keff < 1; > 1 b.
keff = 1; < 0 c.
keff > 1; > 0 d.
keff < 1; < 1 QUESTION A.20
[1.0 point]
Which ONE of the following best describes the reason that, following a reactor scram from full licensed power, indicated reactor power does not immediately decay to zero?
- a. In-core nuclear instrumentation lags the prompt drop.
b.
Core neutron population is sustained by neutrons from the installed neutron source.
c.
Core neutron population is sustained by spontaneous fission of U-235.
d.
Core neutron population is sustained by the delayed neutron precursors.
(***** END OF CATEGORY A *****)
Category B: Normal/Emergency Operating Procedures and Radiological Controls QUESTION B.01
[1.0 point]
In accordance with AFRRI Procedure 004, SCRAMS, Alarms and Abnormal Conditions, all of the following actions should be taken in the event of a low pool level scram alarm EXCEPT:
a.
Turn off the primary pump if pool level is below 4.5.
b.
Initiate pool fill on the auxiliary console.
c.
Verify differential pressure to Reactor Room is maintained.
d.
Ensure the reactor is shutdown.
QUESTION B.02
[1.0 point]
In accordance with AFRRI Technical Specifications, a Senior Reactor Operator (SRO) is required to be present at the reactor for all of the following evolutions EXCEPT:
a.
Movement of an experiment with a reactivity worth of -$1.50.
b.
Restart following a loss of high voltage scram on NMP-1000.
c.
Fuel movement within the reactor.
d.
Restart following a manual scram to support an experiment, where the shutdown checklist has not been completed.
QUESTION B.03
[1.0 point]
In accordance with AFRRI Procedure 200, Fuel Movement and Inspection, which ONE of the following monitoring instruments is NOT required to be operable during fuel movement or handling operations in or near the core?
a.
Continuous Air Monitor above the reactor pool.
b.
NLW-1000 c.
NP-1000 d.
Stack gas monitor
Category B: Normal/Emergency Operating Procedures and Radiological Controls QUESTION B.04
[1.0 point]
A radioactive source reads 250 mRem/hr on contact. Two hours later, the same source reads 100 mRem/hr. How much longer will it take for this source to decay to 25 mRem/hr?
a.
3.03 hr b.
4.22 hr c.
5.18 hr d.
8.50 hr QUESTION B.05
[1.0 point]
In accordance with AFRRI Technical Specifications, the Reactor and Radiation Facilities Safety Subcommittee (RRFSS) will review and approve which ONE of the following experiments prior to implementation?
a.
A previously reviewed and approved exposure room experiment in which a new type of radiation therapy for cancer is tested in rats.
b.
A in-core experiment with a sample which, if it failed, could off-gas 10% of its total gas, resulting in personnel exposure of 80% of 10 CFR 20 annual dose limits.
c.
A modification to a previously reviewed and approved movable experiment, where the reactivity worth of the new experiment has changed from $0.75 to $0.65.
d.
Running the pneumatic transfer system with a rabbit sample containing 30 mg of TNT equivalent.
QUESTION B.06
[1.0 point]
In accordance with the AFRRI Emergency Plan, which ONE of the following individuals may NOT assume the role of Emergency Response Team (ERT) commander?
a.
AFRRI Reactor Facility Director b.
AFRRI Director c.
Reactor Operations Supervisor d.
Any licensed Senior Reactor Operator
Category B: Normal/Emergency Operating Procedures and Radiological Controls QUESTION B.07
[1.0 point]
In accordance with AFRRI Technical Specifications, which ONE of the following surveillances is required to be performed ANNUALLY?
a.
Channel calibration of nuclear instrumentation channels (NP, NPP, etc.).
b.
Control rod drop time measurement and verification.
c.
Low pool water scram test.
d.
Bulk conductivity measurement of the pool water.
QUESTION B.08
[1.0 point]
The exposure rate for a point source is 400 mR/hr at a distance of 2.5 m. What is the exposure rate at a distance of 7 m?
a.
20.1 mR/hr b.
35.7 mR/hr c.
51.0 mR/hr d.
357 mR/hr QUESTION B.09
[1.0 point]
Which ONE of the following statements best describes the Total Effective Dose Equivalent (TEDE)?
a.
The product of the absorbed dose in tissue, quality factor, and all other necessary modifying factors at the location of interest.
b.
The sum of the products of the dose equivalent to the organ or tissue and the weighting factors applicable to each of the body organs or tissues that are irradiated.
c.
The sum of the effective dose equivalent (for external exposures) and the committed effective dose equivalent (for internal exposures).
d.
The dose equivalent to organs or tissues of reference (T) that will be received from an intake of radioactive material by an individual during the 50-year period following the intake.
Category B: Normal/Emergency Operating Procedures and Radiological Controls QUESTION B.10
[1.0 point]
In accordance with AFRRI procedure 004, SCRAMS, Alarms, and Abnormal Conditions, which ONE of the following actions is NOT taken by the reactor operator on receipt of a valid high alarm on the stack gas monitor?
a.
Initiate facility evacuation.
b.
Perform a manual reactor scram and verify reactor shutdown.
c.
Activate the Emergency Plan.
d.
Verify compliance with Technical Specification LCOs.
QUESTION B.11
[1.0 point]
In accordance with AFRRI procedure 215, Thermal Power Calibration, when is detector adjustment performed?
a.
Following completion of each thermal power calibration, regardless of channel indications.
b.
If the channel indication and the calculated power differ by > 3%.
c.
If the channel indication is higher than calculated power by 2% (or greater).
d.
If the channel indication is does not exactly match the calculated power.
QUESTION B.12
[1.0 point, 0.25 each]
In accordance with AFRRI Technical Specifications, which ONE of the following conditions would prohibit reactor operations?
a.
Operation with the Continuous Air Monitor reading 2,000 cpm.
b.
The last measurement of radioactivity on the bulk pool water was made 5 months ago.
c.
Reactor pool level is 2 inches below reference.
d.
Bulk water temperature is 55°C.
Category B: Normal/Emergency Operating Procedures and Radiological Controls QUESTION B.13
[1.0 point]
Which ONE of the following changes would require a License Amendment in accordance with 50.90?
a.
Abandoning-in-place the stack gas radiation monitor and crediting the stack particulate monitor in its place.
b.
Amending the fuel inspection procedure to correct the step numbering system.
c.
Replacing a control rod drive motor with a spare found in storage.
d.
Adjusting the fuel temperature scram setpoint from 575°C to 570°C.
QUESTION B.14
[1.0 point]
Which ONE of the following situations would result in an individual exceeding their 10 CFR 20 yearly occupational dose limit?
a.
Working in proximity to an unshielded check source for 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> where the dose rate is 100 mrem/hr.
b.
Holding an irradiated experiment for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> which emits a dose of 500 mrem/hr.
c.
Working in an exposure room, which has a dose field of 20 mrem/hr, for 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> a day over the course of 20 days.
d.
Working on the reactor top, which has a dose field of 75 mrem/hr, for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> a day over the course of 10 days.
QUESTION B.15
[1.0 point]
In accordance with 10 CFR 20, which ONE of the following statements best describes a High Radiation Area a.
An area accessible to individuals, where radiation levels could result in a dose equivalent of 100 mrem in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> at 30 cm from the source.
b.
An area accessible to individuals, where radiation levels could result in a dose equivalent of 5 mrem in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> at 30 cm from the source.
c.
An area to which access is limited for the purpose of protecting individuals against undue risks from exposure to radiation and radioactive materials.
d.
An area to which access can be limited by the licensee for any reason.
Category B: Normal/Emergency Operating Procedures and Radiological Controls QUESTION B.16
[1.0 point]
All of the following statements regarding operability of the facility radiation monitoring systems are true EXCEPT:
a.
Two Radiation Area Monitors on the reactor Deck must be operable when the reactor is unsecured.
b.
If the Stack Gas Monitor is inoperable, the Stack Particulate Monitor or other portable detector may be substituted for up to one month.
c.
If both reactor bay Continuous Air Particulate Monitors are inoperable, reactor operations are not permissible.
- d. Exposure room Radiation Area Monitors are only required to be operable while operating in the adjacent exposure room.
QUESTION B. 17
[1.0 point]
Which ONE of the following scram channels is NOT required for pulse mode operations?
a.
Fuel temperature b.
Pool water level c.
AC power loss d.
High flux (percent power)
QUESTION B.18
[1.0 point, 0.25 each]
Match the event in Column A to the Emergency Action Level in Column B. Options in Column B may be used once, more than once, or not at all.
Column A a.
Fire in the exposure room that causes structural damage b.
Visual fuel inspection identifies cladding breach on multiple elements c.
Receipt of imminent tornado watch to Bethesda area d.
Unanticipated C2 RAM alarm in High Level Cobalt Facility Column B 1.
Class 0 2.
Notification of Unusual Event 3.
Alert
Category B: Normal/Emergency Operating Procedures and Radiological Controls QUESTION B.19
[1.0 point]
Which ONE of the following evolutions would NOT require performance of AFRRI Procedure 001, Reactor Startup Checklist?
a.
Fuel element visual inspection.
b.
Control rod calibration.
c.
Reactor thermal power calibration.
d.
Following a loss of AC power.
QUESTION B.20
[1.0 point]
In accordance with AFRRI Procedure 215, Thermal Power Calibration, all of the following actions should be taken prior to conducting the evolution EXCEPT:
a.
Ensure the diffusor pump is running.
b.
Turn off primary system pumps at least 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> in advance.
c.
Fill the pool to zero-reference.
d.
Place stirrer into the pool on the north side of the core dolly near the center of the pool.
(***** END OF CATEGORY B *****)
Category C: Facility and Radiation Monitoring Systems QUESTION C.01
[1.0 point, 0.33 each]
Rank the following scenarios from SLOWEST to FASTEST initial rod speed movement when in Steady-State Automatic Mode.
a.
The reactor is at 100 kW and demand power is set at 700kW.
b.
The reactor is at 825 kW and demand power is set at 1 MW.
c.
The reactor is at 500 kW and demand power is set at 475 kW.
QUESTION C.02
[1.0 point]
Which ONE of the following best describes the burnable poison section of the AFRRI TRIGA fuel elements?
a.
Boron mixed with graphite b.
Samarium mixed with zirconium hydride d.
Samarium mixed with aluminum QUESTION C.03
[1.0 point]
Which ONE of the following statements best describes the AFRRI siphon breaks?
a.
A diffusor pump connected to the primary coolant return line perturbates the water approximately 14 feet above the core which introduces air into the system in the event of a primary coolant line break.
b.
A series of small holes is drilled in the suction and return lines approximately 4 inches below the pool surface prevent water from being siphoned out of the pool in the event of a primary coolant line break.
c.
A series of small holes is drilled in the suction lines approximately 8 inches below the pool surface prevent water from being siphoned out of the pool in the event of a primary coolant line break.
d.
A diffusor pump connected to the primary coolant suction line perturbates the water approximately 14 feet above the core which introduces air into the system in the event of a primary coolant line break.
Category C: Facility and Radiation Monitoring Systems QUESTION C.04
[1.0 point]
Which ONE of the following statements regarding operability of the ventilation system is true?
a.
The reactor may be operated with the ventilation system out of service for periods of time not to exceed two continuous hours for maintenance, repair, or testing.
b.
If the ventilation system fails during reactor operation, operations may continue as planned for up to four hours, however the reactor may not restart until the ventilation is returned to operable status.
c.
The ventilation system is only required to be in service during pulse mode operations.
d.
Reactor operations may continue indefinitely with the ventilation system inoperable, provided the ventilation dampers are verified closed.
QUESTION C.05
[1.0 point]
Which ONE of the following is NOT a feature of NMP-1000 (Linear Power Channel)?
a.
Overpower scram at 110% of selected range when manually scaled by the operator.
b.
Indication of reactor power from source range through 120% of full power.
c.
Interlock at 20% loss of high voltage to power supply.
d.
Control rod withdrawal prohibit if power < 1 x 10-5 W.
QUESTION C.06
[1.0 point]
Which ONE of the following statements best describes the reason for the core location of the instrumented fuel elements (IFE)?
a.
The IFEs are located in the A and C rings because that is where the highest power density and fuel temperatures occur so the difference between the true and measured temperatures is only a few degrees.
b.
The IFEs are located in the B and C rings because that is where the highest power density and fuel temperatures occur so the difference between the true and measured temperatures is only a few degrees.
c.
The IFEs are located in the D ring because the power density is evenly distributed in this region, ensuring that the measured temperature is reflective of the average core temperature.
d.
The IFEs are located in the C and D rings because the power density is evenly distributed in this region, ensuring that the measured temperature is reflective of the average core temperature.
Category C: Facility and Radiation Monitoring Systems QUESTION C.07
[1.0 point]
Which ONE of the following statements best describes the purpose of the 3 second period interlock?
a.
Prevents movement of standard control rods in pulse mode to prevent inadvertent reactivity addition.
b.
Ensures that the reactor will not go prompt critical by limiting the amount of reactivity added per unit time.
c.
Ensures adequate time for the operator to take manual action to control power ascension in automatic mode.
d.
Minimized the possibility of exceeding the maximum permissible power level or fuel temperature safety limit.
QUESTION C.08
[1.0 point]
Which ONE of the following statements best describes the AFRRI regulating rod drive mechanisms?
a.
An electromagnetically coupled motor, gear reduction system, and an acme screw type drive.
b.
An electromechanical drive, with a stepper motor, magnetic rod coupler, and rack-and-pinion gear system.
c.
Two 2-phase electric servo motors in parallel driving a lead-screw nut combination.
d.
A pneumatic-electromechanical drive with an electric motor, ball-nut drive assembly, and externally-threaded air cylinder.
QUESTION C.09
[1.0 point]
Which ONE of the following statements best describes the current AFRRI standard and transient control rod design?
a.
The standard control rods are void-followed and the transient rod is poison followed.
b.
The standard control rods are fuel-followed and the transient rod is aluminum followed.
c.
The standard control rods are water-followed and the transient rod is void followed.
d.
The standard control rods are water-followed and the transient rod is fuel-followed.
Category C: Facility and Radiation Monitoring Systems QUESTION C.10
[1.0 point]
In accordance with AFRRI Technical Specifications, which ONE of the following statements best describes the reason for the requirement that the reactor not be operated if pool level drops below 14 feet from the top of the core?
a.
This level provides an indication to the reactor operator that make-up water should be added to the core.
b.
This level ensures that the departure of nucleate boiling ratio (DNBR) is maintained greater than unity.
c.
This level ensures no water hammer will occur in the primary coolant system piping due to the introduction of air into the system.
d.
This level ensures sufficient biological shielding to the reactor bay and sufficient cooling capacity for the reactor.
QUESTION C.11
[1.0 point]
Which ONE of the following statements best describes the operation of the AFRRI radiation area monitors?
a.
An ion chamber specifically utilizing boron to distinguish between neutrons and gammas to provide an effective biological dose rate.
b.
A Geiger Mueller detector attenuated to a proportional energy to produce a dose rate.
c.
A Geiger Mueller detector that uses a bimetallic film to discriminate between high and low energy betas and gammas to produce a dose rate d.
An NaI Scintillator Detector that emits varying intensities of light based on the energy of the radioactive particle incident on the detector.
QUESTION C.12
[1.0 point]
In accordance with the AFRRI Technical Specifications, which ONE of the following statements best describes the primary basis for measuring pool water conductivity?
a.
This is monitored to help minimize the activation of impurities in the water system and monitor the possibility of corrosion in the fuel cladding or reactor system components.
b.
This is monitored to determine when the resins in the demineralizer column need to be changed.
c.
This is monitored to primarily detect any leakage of secondary cooling into the primary cooling system.
d.
This is monitored to detect any leakage of primary coolant.
Category C: Facility and Radiation Monitoring Systems QUESTION C.13
[1.0 point]
Which ONE of the following statements best describes the purpose of the wood lining in the Exposure Rooms?
a.
Wood prevents scattering of thermal neutrons, which ensures a constant neutron flux into the exposure rooms.
b.
Wood serves as the primary biological shield of the exposure rooms.
c.
Wood effectively shields the exposure rooms from gamma radiation.
d.
Wood minimizes fast neutron activation of the concrete biological shield and reduces the effects of secondary gamma radiation.
QUESTION C.14
[1.0 point]
Which ONE of the following statements best describes the Uninterruptible Power Supply (UPS)?
a.
The UPS provides approximately 15 minutes of power to the entire console during a loss of power event, allowing the reactor operator to monitor reactor shutdown following an automatic scram.
b.
The UPS provides power to the entire console during a loss of power event, allowing the reactor operations to continue without interruption.
c.
The UPS provides approximately 15 minutes of power to Technical Specification required components only during a loss of offsite power.
d.
The UPS is the main power source for the digital console only during emergency reactor operations.
QUESTION C.15
[1.0 point]
Which ONE of the following statements best describes the importance of maintaining a negative pressure in the reactor room compared to the rest of the AFRRI facility?
a.
This ensures that all air leakage is out of reactor confinement, which controls the release of radioactive effluents to the environment through the stack during emergency conditions.
b.
This ensures the reactor is isolated such that environmental controls such as temperature and humidity are maintained within a narrow band to prevent degradation of reactor protection system components.
c.
This ensures that all air leakage is out of reactor confinement, ensuring adequate radiological controls for occupational workers.
d.
This ensures that all air leakage is into reactor confinement, which controls the release of radioactive effluents to the environment through the stack.
Category C: Facility and Radiation Monitoring Systems QUESTION C.16
[1.0 point]
In accordance with AFRRI Technical Specifications, which ONE of the following statements best describes the basis for the maximum step insertion of reactivity in pulse mode?
a.
Limiting the reactivity insertion establishes the maximum achievable power should the transient rod remain stuck in the fully withdrawn position following a pulse.
b.
Limiting the reactivity insertion will prevent peak fuel temperatures in excess of 830°C, ensuring the Safety Limit will not be exceeded.
c.
Limiting the reactivity insertion ensures the reactor can still be shut down from any operation condition, even if the transient rod remains stuck in the fully withdrawn position following a pulse.
d.
Limiting the reactivity insertion will prevent peak fuel temperatures in excess of 600°C, ensuring the Limiting Safety System Setting will not be exceeded.
QUESTION C.17
[1.0 point]
Which ONE of the following statements best describes the dashpots on control rod rods?
a.
The dashpots slow the upward movement of the transient control rod over the last two inches of travel to reduce the impact of transient rod vibration during a pulse.
b.
The dashpots slow the downward movement of the standard control rod over the last two inches of travel to reduce bottoming impact during a scram.
c.
The dashpots ensure the control rods move freely in the upper portion of the barrel.
d.
The dashpots slow the upward movement of the standard control rod over the last two inches of travel to ensure the maximum reactivity insertion rate does not exceed Technical Specification limits.
QUESTION C.18
[1.0 point]
In accordance with AFRRI Technical Specifications, which ONE of the following statements regarding the radiation monitoring systems is true?
a.
A high-level alarm on the Continuous Air Particulate Monitor (CAM) initiates closure of ventilation system dampers.
b.
A high-level alarm on the Stack Gas Monitor will initiate a reactor scram and automatically close the ventilation system dampers.
c.
A high alarm on one of the two Radiation Area Monitor will automatically initiate a reactor scram.
d.
A high alarm on both Radiation Area Monitors will initiate an evacuation alarm and a reactor scram.
Category C: Facility and Radiation Monitoring Systems QUESTION C.19
[1.0 point]
A radioactive isotope commonly produced in the exposure rooms is ______, and potential exposure from its production is mitigated by ________.
a.
Ar-41; purging the air from the room with CO2 before staff enters.
b.
N-16; a 10-minute time delay on the doors to allow for sufficient decay before staff enters.
c.
Ar-41; a negative differential pressure inside the exposure room.
d.
N-16; operation of a diffusor pump on the reactor side of the exposure room walls.
QUESTION C.20
[1.0 point]
Which ONE of the following statements best describes the design of the NLW-1000 (Log Power Monitor Channel)?
a.
It is an unlined gamma ionization chamber.
b.
It is a fission chamber lined with highly enriched U-235.
c.
It is a compensated ion chamber lined with B-10.
d.
It is an uncompensated ion chamber filled with BF3 gas.
(***** END OF CATEGORY C *****)
(********** END OF EXAMINATION **********)
Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics A.01 Answer:
c.
Reference:
Burn, Introduction to Nuclear Reactor Operations, Section 3.3.4, p. 3-23.
= (Keff1-Keff2)/(Keff1*Keff2)
= (0.925-0.750) / (0.925*0.750)
= 0.252
- 100
= 25.2% k/k A.02 Answer:
- a. 2 (Withdraw); b. 1 (Insert); c. 3 (No movement); d. 2 (Withdraw)
Reference:
Burn, Introduction to Nuclear Reactor Operations, p. 7-17 A.03 Answer:
a.
Reference:
DOE Fundamentals Handbook, Vol. 2, Module 3, p. 16 A.04 Answer:
b.
Reference:
DOE Fundamentals Handbook, Vol. 1, Module 1, p. 61 A.05 Answer:
c.
Reference:
DOE Fundamentals Handbook, Volume 2, Module 3, p. 21,
T*T
= (-0.00095 k/k /oF) * (-15oF) = 0.0143k/k A.06 Answer:
d.
Reference:
DOE Fundamentals Handbook, Vol. 2, Module 3, p. 41-42 A.07 Answer:
a.
Reference:
DOE Fundamentals Handbook, Vol. 2, Module 3, p. 15 A.08 Answer:
c.
Reference:
DOE Fundamentals Handbook, Vol. 2, Module 4, p. 25 A.09 Answer:
c.
Reference:
Burn, Introduction to Nuclear Reactor Operations, p. 3-19 and 6-14
Category A: Reactor Theory, Thermodynamics, and Facility Operating Characteristics A.10 Answer:
a.
Reference:
CR1 / CR2 = (1 - Keff2) / (1 - Keff1) 450 / 700 = (1 - Keff2) / (1 - 0.875)
.6428 * (0.125) = 1 - Keff2 Keff2 = 0.91964
= (Keff2 - Keff1) / (Keff2
- Keff1)
= (0.91964 - 0.875) / (0.91964
- 0.875) = 0.0554 A.11 Answer:
a.
Reference:
Burn, Introduction to Nuclear Reactor Operations, p. 2-28 A.12 Answer:
d.
Reference:
DOE Fundamentals Handbook, Vol. 1, Module 2, p. 17 A.13 Answer:
d.
Reference:
Burn, Introduction to Nuclear Reactor Operations, p. 3-31 A.14 Answer:
b.
Reference:
Burn, Introduction to Nuclear Reactor Operations, p. 2-28 A.15 Answer:
d.
Reference:
DOE Fundamentals Handbook, Vol. 2, Module 3, p. 3 A.16 Answer:
c.
Reference:
1.02*0.71*0.97*0.99*1.57*0.92 = 1.004 (critical)
A.17 Answer:
a.
Reference:
Burn, Introduction to Nuclear Reactor Operations, p. 2-37 A.18 Answer:
d.
Reference:
Burn, R., Introduction to Nuclear Reactor Operation, Section 5.3, p. 5-12 A.19 Answer:
c.
Reference:
Burn, Introduction to Nuclear Reactor Operations, p. 3-21 A.20 Answer:
d.
Reference:
Burn, Introduction to Nuclear Reactor Operations, p. 3-7
(***** END OF CATEGORY A *****)
Category B: Normal/Emergency Operating Procedures and Radiological Controls B.01 Answer:
c.
Reference:
004, SCRAMS, Alarms, and Abnormal Conditions B.02 Answer:
d.
Reference:
AFRRI Technical Specifications 6.1.3.2 B.03 Answer:
c.
Reference:
200, Fuel Movement and Inspection B.04 Answer:
a.
Reference:
DR = DR*e-t 100 mrem/hr = 250 mrem/hr* e -(2hr) 0.4 = e -(2hr) ln(0.4) = ln(e-*2 hr)
-0.916 = -*2 hr
= 0.458 Solve for t:
25 mrem/hr = 100 mrem/hr* e -0.458(t) 0.25 = e -0.458(t) ln(0.25) = ln(e-0.458*t)
-1.386 = -0.458 t t = 3.03 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> B.05 Answer:
b.
Reference:
AFRRI Technical Specifications 3.6 and 6.2.4 B.06 Answer:
b.
Reference:
AFFRI Emergency Plan, p. 3-6 B.07 Answer:
a.
Reference:
AFRRI Technical Specifications 4.2.2 B.08 Answer:
c.
Reference:
l2 = l1D12/d22 l2 = (400 mR/hr)(2.5m)2 / (7m)2 l2 = 51 mR/hr B.09 Answer:
c.
Reference:
Category B: Normal/Emergency Operating Procedures and Radiological Controls B.10 Answer:
a.
Reference:
004, SCRAMS, Alarms, and Abnormal Conditions B.11 Answer:
b.
Reference:
215, Thermal Power Calibration B.12 Answer:
b.
Reference:
AFFRI Technical Specifications 3.3, 3.6 and 4.3 B.13 Answer:
a.
Reference:
10 CFR 50.59 and 559, 50.59 Screening and Evaluation Process B.14 Answer:
d.
Reference:
- a. 100 mrem/hr
- 5 hrs = 500 mrem
- b. 500 mrem
- 2hrs = 1000 mrem
- c. 20 mrem/hr
- 5 hrs
- 20 = 2000 mrem
- d. 8 hrs
- 10 days
- 75 mrem/hr = 6000 mrem B.15 Answer:
a.
Reference:
10 CFR 20.1003 B.16 Answer:
b.
Reference:
AFRRI Technical Specifications 3.5.1 B.17 Answer:
d.
Reference:
AFRRI Technical Specifications 3.2.2 B.18 Answer:
- a. 3 (Alert); b. 3 (Alert); c. 1 (Class 0); d. 2 (NOUE)
Reference:
AFRRI Emergency Plan, p. 6-8 B.19 Answer:
a.
Reference:
001, Rector Startup Checklist B.20 Answer:
a.
Reference:
215, Thermal Power Calibration
(***** END OF CATEGORY B *****)
Category C: Facility and Radiation Monitoring Systems C.01 Answer:
- 1. c; 2. b; 3. a
Reference:
002 Reactor Operations, p. 6 C.02 Answer:
d.
Reference:
AFRRI SAR 4.2.1 C.03 Answer:
b.
Reference:
AFRRI SAR 5.2 C.04 Answer:
a.
Reference:
AFRRI Technical Specifications 3.4 C.05 Answer:
a.
Reference:
AFRRI SAR 7.2.2.1.2 C.06 Answer:
b.
Reference:
AFRRI Technical Specifications 2.2 C.07 Answer:
d.
Reference:
AFRRI Technical Specifications 3.2.2 C.08 Answer:
b.
Reference:
AFRRI SAR 4.6.2 C.09 Answer:
b.
Reference:
AFRRI SAR 4.2 C.10 Answer:
d.
Reference:
AFRRI SAR 7.4.4 and Technical Specifications 3.2.2 C.11 Answer:
b.
Reference:
AFRRI SAR 7.8.1 C.12 Answer:
a.
Reference:
AFRRI Technical Specifications 4.3 C.13 Answer:
d.
Reference:
AFFRI SAR 10.2.1.1
Category C: Facility and Radiation Monitoring Systems C.14 Answer:
a.
Reference:
AFRRI SAR 7.6.3.2 C.15 Answer:
d.
Reference:
AFRRI SAR 9.1 C.16 Answer:
b.
Reference:
AFRRI Technical Specifications 3.1.2 C.17 Answer:
b.
Reference:
AFRRI SAR 4.6.2 C.18 Answer:
a.
Reference:
AFRRI SAR 3.5.1 C.19 Answer:
c.
Reference:
AFRRI SAR 10.2.2 C.20 Answer:
b.
Reference:
AFRRI SAR 7.2.2.1.1
(***** END OF CATEGORY C *****)
(********** END OF EXAMINATION **********)