SOLUTION MANUAL
SOLUTION MANUAL
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Chapter 1 - Principal Characteristics of Power Reactors
2. Which of these combinations would be best for submarine propulsion? Explain your choice. 3. State the single most important power cycle parameter affecting the cycle thermal efficiency. 4. Compare the primary side pressures of a PWR, a BWR and a MSR. Describe the reason for primary side pressure of the PWR being about twice the BWR and the advantage of MSR primary side pressure being close to atmospheric. 5. Comparing the core of a BWR with that of a PWR, explain the reason a BWR is considered a closed and a PWR an open core design. 6. Explain the reason that alloys of zirconium are used for fuel cladding. 7. Compare the number of coolant loops and fluids used in a BWR with those of a LMFR describe the reason for the differences, if any. 8. What is the key difference in the VVER design from other LWR designs? 9. How do you classify a LFR with respect to neutron spectrum and thermal efficiency as compared with the SFR? 10. Describe the key difference with respect to core coolant circulation between NuScale and a typical LWR.
PROBLEM 1.1 SOLUTION World Utilization of Power Reactor Technology Question 1 Note:
Descriptions are made with (coolant type) – (moderator). The following notes are keyed to Table 1.13
A
Pressurized Water Reactor (PWR). Used by: – USA – France – Germany – Former USSR
B
Boiling Water Reactor (BWR), Used by: – USA – Germany
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Chapter 1 - Principal Characteristics of Power Reactors
– Sweden C
Press. Heavy Water Heavy Water Vessel – AGESTA (Sweden) – R - 3/ ADAM (Sweden) – ATUCHA (Argentina) – MZFR (Germany) – BRUCE 1-8 (Canada) – CP - 5 (USA) – NPD -2 (USA)
D
Boiling Heavy Water - Heavy Water Vessel – MARVIKEN (Sweden) – HALDEN BWR (Norway) – ATUCHA 2 (Argentina)
E
Press. Light Water Heavy Water Tube – NRX (Canada) – GENKILLY 2 (Canada) – SGHRW – CIRUS/TROMBAY (India)
F
Boiling Light Water Heavy Water Tube – CIRENE (Italy) – BLW 250 (Canada) – FUGEN (Japan) – VENUS (Belgium)
G
Press. Heavy Water - Heavy Water Tube – CANDU (Canada) – PRTR (Canada) – CVTR (Canada) – NPD (Canada)
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Chapter 1 - Principal Characteristics of Power Reactors
– KARLSRUHE (Germany) – PICKERING (Canada) H
Boiling Heavy Water Heavy Water Tube – NPD CONVERSION (Canada)
I
Organic - Heavy Water Tube – WR-1 – ESSOR – ORGEL – DON – HWOCR
J
Gas - Heavy Water Tube – BOHUNIZE (Czechoslovakia) – KKN (Germany) – EL-2, EL-4 (France) – LUCENS (Switzerland)
K
Press. Light Water Graphite – APS OBNINSK (Former USSR) – CHERNOBYL (Ukraine) – HANFORD (USA) – RBMK (Former USSR)
L
Boiling Light Water - Graphite – SOSNOVY BORINSK (Former USSR) – BELOYARSK (Former USSR) – FIRST NUCLEAR REACTOR OF USSR – N REACTOR (USA)
M
Gas - Graphite – MAGNOX (Great Britain)
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Chapter 1 - Principal Characteristics of Power Reactors
– DRAGON (Great Britain) – HTGR (EGCR, PEACHBOTTOM, FT. ST. VRAIN, HINKLEY POINT B), (USA) – UTREX (USA) – AVR (Germany) – SIZEWELL NPS (Great Britain) – HECTOR – KIWI – NERVA – USA SPACE PROGRAM N
Liquid Metal - Graphite – HALLAM (USA) – MOLTEN SALT REACTOR EXPERIMENT (ORNL, USA)
O
Gas - Beryllium
P
– EBOR (USA) – DANIEL’S PILE (ORNL, USA) Organic - Organic – PIQUA (USA)
Q
Press. Light Water -Beryllium – MIR (Russia) – GE TEST REACTOR (USA) – MR-2 – MIR (Russia)
R
Boiling Light Water Beryllium – BR 2 (Belgium)
S
Boiling Light Water Organic – AGN-211 (Switzerland)
T
Gas - Light Water – ESADA VESR (USA) – MOBILE LOW POWER PLANT (USA) – ML-1 (Idaho Falls, USA) – HEAT TRANSFER REACTOR EXPERIMENT (USAF)
U
Organic Heavy Water Vessel
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Chapter 1 - Principal Characteristics of Power Reactors
– ECO (Italy) V
Gas - Heavy Water Vessel – HWGCR (Former USSR)
W
Liquid Metal - Beryllium – SUBMARINE INTERMEDIATE REACTOR (USA)
X
Press, Light Water Organic – L-77 (Univ, of Nevada, USA)
Answer to Question 1 continued. Comments on moderator-coolants which have been utilized worldwide. 1. There is no advantage gained here by using a light water moderator with a different coolant, because light water is already being used to moderate, it is simpler and more economical to use it as a coolant as well. 2. Liquid sodium will react with water. Using sodium as a coolant would require extensive (and expensive) efforts to separate the two materials (i.e., a tertiary loop). 3. Separation of light and heavy water is not feasible in a vessel-type reactor. If they were both placed in the vessel, the advantages of heavy water would be lost by dilution with light water. 4. In a vessel type reactor you cannot separate the coolant from the moderator. 5. It is unnecessarily expensive to use heavy water as a coolant if it is not being used for its excellent moderating ability. Since graphite is the moderator here it is more economical to use light water as the coolant (even though it has a higher absorption cross section than heavy water.) 6. This is an uneconomical combination. If the organic is being used as the coolant it should be used as the moderator as well. 7. Beryllium is expensive, toxic, brittle, and hard to work with. For a power reactor there are plenty of better choices. 8. Because the organic is the moderator, it is more economical to sue it as the coolant as well. The decomposition of organics under radiation will pose a problem if the organic is not being used as the moderator AND the coolant. If it is not circulating as a coolant its residence time in the core will be too long, leading to decomposition.
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Chapter 1 - Principal Characteristics of Power Reactors
TABLE SM-1.1: Summary Coolant Pressurized Boiling light Pressurized Boiling (right), light water water heavy heavy Moderator water water (down)
Light Water A Heavy water 3 (vessel) Heavy E water (tube)
Organic Gas Liquid (HB-40, (Hydrogen, Metal Santowax- Nitrogen, (NaK, Na) OM) Carbon dioxide, Helium) 1(USADA B 1 1 1 2 VERS, USA) Marketplace to Buy and Sell your Study Material 43 C D 4 (HWGCR, 2,4 USSR) F
G
H
I
J
2
Graphite
K (APS) L
5
5
6
M
M (MSRE)
Beryllium
Q (MIR, Russia GE test reactor)
R (BR-2, Belgium)
7
7
7
0
7
8
S (AGN211, Basel, 8 Switzerland)
8
P
8
8
Organic
Question 2. Which of these combinations would be best for submarine propulsion? Explain your choice. Submarine propulsion reactors are generally designed for military ships. We may identify some characteristics which might be desirable for nuclear military submarines: – – – – – – – –
High reliability Low weight: high power density Low volume Very low toxic release, especially in cruise space Silent operation Tolerance to acceleration (in case of attack) and battle damage Power variation capability Ease of operation
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Chapter 1 - Principal Characteristics of Power Reactors
– Long fuel residence time – Need for both propulsion and electricity generation – Fuel cost is not a big concern In order to ensure reliability under acceleration, boiling water reactors should be avoided, because of the large density difference between the liquid and the vapor phase. Gas-cooled reactors should be avoided because of the large required volume, the risk of leaks and the high gas velocity, which may result into noisy operation. Since there is no limitation to fuel enrichment, there is no particular need for special moderating materials such as heavy water, graphite or organic. Therefore, pressurized light water-cooled and moderated reactors are good options. Light water has several advantages, among which are: – – – –
Small slowing down length, which allows for a compact core. Can be used in both the primary and secondary systems, simplifying the design. Neutron activation products have a short half-life. Can be easily distilled from seawater to provide makeup and safety function inventory.
Alternatively, liquid metal-cooled reactors may be used if corrosion is under control. If liquid metal coolants are used, electromagnetic pumps may be installed which allow more silent operation. However, sodium coolants have the drawback of reacting violently with water, producing explosive/flammable hydrogen. Question 3. State the single most important power cycle parameter affecting the cycle thermal efficiency. Coolant Outlet Temperature—it dictates reactor mission capability e.g. process heat and cycle thermal efficiency which affects capital cost. Also importantly it affects coolant corrosion performance. Question 4. Compare the primary side pressures of a PWR, a BWR and a MSR. Describe the reason for primary side pressure of the PWR being about twice the BWR and the advantage of MSR primary side pressure being close to atmospheric. PWR - 15.5MPa, BWR - 7.17 MPa, MSR - nominal 1 MPa PWR pressure is high to keep the primary coolant in the subcooled regime while still achieving high operating temperatures MSR nominal atmospheric primary operating pressure keeps stored energy in the salt coolant low which is a beneficial safety factor as well as allowing the primary coolant system pressure containment e.g. piping to be thin walled. Question 5. Comparing the core of a BWR with that of a PWR, explain the reason a BWR is considered a closed and a PWR an open core design. The BWR operates with a boiling mixture from about one third the distance from the core flow inlet. Particularly in the boiling region different axial pressure levels in adjacent coolant channels 13
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Chapter 1 - Principal Characteristics of Power Reactors
develop due to the core radial neutron flux shape which in turn cause radial pressure gradients to develop between coolant channels. These radial pressure gradients in turn cause radial flows to develop between coolant channels which are countered in BWRs by use of smaller radial sized bundles than in PWRs (a closed core design) . Also since the PWR does not operate in the boiling region, radial pressure gradients of BWR magnitude do not develop so that PWRfuelassemblies do not have bounding walls (an open core design). Question 6. Explain the reason that alloys of zirconium are used for fuel cladding. Zirconium has low neutron capture cross section and sufficient strength and corrosion resistance at water cooled reactor operating temperatures Question 7. Compare the number of coolant loops and fluids used in a BWR with those of a LMFR - describe the reason for the differences, if any. The BWR uses a direct cycle, hence a single water coolant loop while the LMFR uses a threecoolant loop system. Both use the steam cycle. The LMFR loops are the primary sodium loop, the intermediate loop between the intermediate heat exchange and the steam generator typically to date also using sodium coolant and finally a water coolant in which steam is produced which flows to the turbine in this third loop. Question 8. What is the key difference in the VVER design from other LWR designs? The VVER uses hexagonal shaped fuel assemblies and horizontal steam generators. Question 9. How do you classify a LFR with respect to neutron spectrum and thermal efficiency as compared with the SFR? Both are fast neutron spectrum reactors. The primary coolant outlet temperatures arerespectively550 degrees Centigrade with thermal efficiencies of 43-44 %. Question 10. Describe the key difference with respect to core coolant circulation between NuScale and a typical LWR. The Nuscale design is natural circulation using a helical coil steam generator operating in a oncethru producing superheated steam. A module produces 60 MWe with a plant composed of 12 modules. The typical LWR ( let’s take the PWR) is a forced circulation primary loop operatingwith a U tube pot type steam generator producing saturated steam (Westinghouse) or asteamgenerator of the once-thru design producing superheated steam (the Areva design).
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