NATIONAL OPEN UNIVERSITY OF NIGERIA
PLOT 91, CADASTRAL ZONE, NNAMDI AZIKIWE EXPRESSWAY, JABI - ABUJA
FACULTY OF SCIENCES
DEPARTMENT OF PURE AND APPLIED SCIENCE
2019_1 SEMESTER EXAMINATION
COURSE CODE: PHY 456
COURSE TITLE: NUCLEAR REACTOR PHYSICS
CREDIT UNIT 3
TIME ALLOWED (2½ HRS)
INSTRUCTION: Answer question one (1) and any other four (4)questions
QUESTION 1
(a). List five ways in which neutrons can interact with nuclei.
(2.5 marks)
(b). What is a moderator?
(4 marks)
(c). What is a nuclear reactor?
(4 marks)
(d). What is meant by the following terms: nuclear power, nuclear energy and atomic energy?
(4.5 marks)
(e). Consider the following nuclear fusion reaction that uses deuterium and tritium as fuel.
(i). Complete the reaction equation. What is the name of the new particle released during
the reaction?
(2 marks)
(ii). Given the following information;
,, ,
Determine the mass defect of a single reaction
(2 marks)
(iii). Determine the energy in joules released during a single fusion reaction.
(3 marks)
QUESTION 2
(a). Explain, using your knowledge of criticality and nuclear reactions, why water makes a fantastic moderator.
(4 marks)
(b). What are the qualities of a good control rod material?
(2 marks)
(c). Define the following terms: (i) subcritical system;
(2 marks)
(ii) critical system;
(2 marks) and supercritical system
(2 marks)
QUESTION 3
(a). If there are n scattering centers (nuclei) per unit volume, each of area σ, in a thin target of thickness dT, find the ratio R of the area covered by scattering centers to the total are of the targets.
(2 marks)
(b). Given that and . Show that. It must be assumed that all symbols carried their usual meanings.
(7 marks)
(c). Describe moderation.
(3 marks)
QUESTION 4
(a).What is macroscopic cross section?
(1.5 marks)
(b). Why is it possible to produce the fission of U-235 with slow neutrons whereas it is necessary to use fast neutrons to produce the fission of U-238?
(9 marks)
(c). Define cross section
(1.5 marks)
QUESTION 5
(a). Concisely discuss the following as related to nuclear reaction:
(i) Radiative capture
(1.5marks); (ii) Charged-particle reactions
(1.5marks)
(b). Write a short note on (i). Nuclear fission
(2 marks) (ii). Nuclear fusion
(2 marks)
(c). Determine the product nucleus and Q value in the equation comment on your result. (Masses of Al, Mg, d and α are 26.9901 amu, 24.9936 amu, 2.0147 amu and 4.0039 amu respectively)
(5marks)
QUESTION 6
(a). Determine the unknown particles X in the following nuclear reactions:
- , (2 marks)
- , (2 marks)
- (2 marks)
(b). As observed in the laboratory system, a 8 MeV proton is incident on a stationary carbon-12 target. Find the velocity of the centre of mass system. Take the mass of the proton to be 1 amu.
(4 marks)
(c). State Fick’s law.
(2 marks)
NATIONAL OPEN UNIVERSITY OF NIGERIA
DEPARTMENT OF CRIMINOLOGY AND SECURITY STUDIES
FACULTY OF SOCIAL SCIENCES
2019_1 EXAMINATION QUESTIONS
COURSE CODE: CSS 356
COURSE TITLE: TRADITIONAL AND INFORMAL MECHANISMS OF CRIME CONTROL
CREDIT UNIT: 3
TME ALLOWED: 3 HOURS
INSTRUCTION: ANSWER ANY FOUR QUESTIONS
- Differentiate between traditional and informal mechanism of crime control. (17.5 marks)
- Explain the relationship among control, justice and law. (17.5 marks)
- Discuss the factors enabling indigenous social control in modern African States. (17.5 marks)
- Briefly discuss the functions of the “Ayelala” traditional control mechanism of crime. (17.5 marks).
- Discuss the main characteristics of traditional, Informal justice system that explains their contribution to better access to crime control. (17.5 marks)
- Explain the reasons why some people may not use formal control mechanism. (17.5Marks)