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CIVIL NUCLEAR MARITIME PROPULSION CYCLE EVALUATION
DUE DATE: APRIL 25, 2016
NAME: BRETT MERCER
INSTRUCTOR: DR. BOLOTNOV
ABSTRACT
A nuclear powered vessel, the N.S. Tarasenko, has been chosen as a “green” initiative to move
towards clean ship travel while transporting cargo. Evaluations of steam cycles were conducted
in an attempt to improve the overall steam cycle efficiency. The assessment of the N.S.
Tarasenko’s steam cycle observed the effects of a simple cycle design vs. a combined design,
evaluation of different condenser pressures during operation in a variety of seawater
temperatures, multiple low pressure turbine tap pressures, actual vs. idealistic steam cycles, and
the amount of thermal power output needed to propel the N.S. Tarasenko during the
transportation of cargo. An Excel software was established to calculate the cycle efficiencies due
to the aforementioned parametric studies. The analysis showed that a combined cycle design
yielded the highest cycle efficiency during operation in January. The study established the
thermal power that the reactor would need to generate to achieve the operational ship speed.
TABLE OF CONTENTS
INTRODUCTION AND THEORY.................................................................1
METHODS.................................................................................................2
RESULTS AND DISCUSSIONS.....................................................................4
CONCLUSIONS .......................................................................................12
REFERENCES .........................................................................................13
INTRODUCTION AND THEORY
President Dwight D. Eisenhower first proposed the design of a commercialized nuclear powered
vessel in 1955 as evidence of the United States’ interest in the peaceful use of atomic energy. On
October 15, 1956, the President directed the Atomic Energy Commission (AEC) and the
Maritime Administration (MARAD) to proceed with the design and construction of the N.S.
Savannah and was commissioned in 1959, per reference (1). Via reference (2), the N.S.
Savannah was designed as a national showpiece to demonstrate to the world the intent of the
United States to employ the power of the atom for peaceful, productive purposes. Due to not
being a viable, cost-effective merchant ship, the N.S. Savannah was decommissioned in 1972
after the Department of Defense (DoD) announced that oil-fired freighters were more cost
effective than nuclear-powered vessels, per reference (3). Since the N.S. Savannah had extensive
information readily available to the general public, the merchant ship was used as a model for the
design scope of the project.
In today’s world economy, the United States plays a predominant role in the importation and
exportation of trade goods. Per reference (4), the United States ranks 1st in imports and 3rd in
exports. Majority of these good are transported by merchant ships running on diesel fuel for
propulsion needs. It is important to note that shipping also releases pollutants into the
atmosphere as the ship burns fuel for propulsion. Per reference (5), one E-Class cargo ship emits
pollution equivalent to 50 million cars. A “green” initiative to move towards a clean means of
ship propulsion is vital to lower the impact on the environment. Due to the advancements in
nuclear technology in recent years, one such solution to this problem is to design a new wave of
nuclear merchant vessels similar to the N.S. Savannah.
The problem with a nuclear powered vessel is that the thermal efficiency is much lower than that
of a civil nuclear power plant due to space constraints for the steam system aboard a ship, as well
as the need for flexible power output while at sea, per reference (6). A typical nuclear ship has a
thermal efficiency of approximately less than 20%, compared to 33% for a commercial
Pressurized Water Reactor (PWR). The intent of this project was to examine several parametric
studies with a goal of improving the overall secondary steam cycle efficiency via evaluation of
different condenser pressures due to variations in seawater temperatures, multiple low pressure
turbine tap pressures, introduction of moisture separator and reheaters, and actual versus
idealistic steam cycles for a new nuclear merchant ship, the N.S. Tarasenko. Also, an analysis of
the necessary power generated in order to achieve a certain ship speed was performed.
1
METHODS
An Excel program was utilized for the calculation purposes of this project. Excel software titled
(IAPWS-IF97) Steam97 Excel Add-In1 was downloaded via reference (7). The software enables
the user to determine several steam table properties, which can be see in attachment (1). The
Steam97 Excel Add-In steam table properties have been verified to be accurate by comparison
with reference (8). The software is able to determine steam properties within the following
temperature and pressure parameters: 0.1 psia ≥ Pressure ≥ 3200 psia, 32 °F ≥ Temperature ≥
3631 °F. Once the software was imported into Excel, functions were created in order to calculate
the necessary parameter values for steam cycles. The calculable properties used for this project
when given pressure, and both pressure and temperature can be observed in Table 1.1 and 1.2.
Steam Property Function Code Label
Saturation Temperature Tsat_p(pressure)
Density Fluid rhoL_P(pressure)
Density Vapor rhoV_P(pressure)
Enthalpy Fluid hL_p(pressure)
Enthalpy Vapor hV_p(pressure)
Entropy Fluid sL_p(pressure)
Entropy Vapor sV_p(pressure)
Table 1.1: Calculable Steam Properties When Given Pressure
Steam Property Function Code Label
Density rho_pT(pressure, temperature)
Enthalpy h_pt(pressure, temperature)
Entropy s_pt(pressure, temperature)
Table 1.2: Calculable Steam Properties When Given Pressure and Temperature
The subsequent instructions, along with Table 1.3, provide details to show how a particular set of
steam properties can be determined when the pressure at a state point for a steam cycle is
manually entered. For this example, the state within the cycle in which steam leaves the steam
generator (i.e. 500 psia) will be evaluated:
1. Insert pressure value (=500 psia).
2. Insert code function for saturation temperature (=Tsat_p(500 psia)).
3. Insert code function for fluid enthalpy (=hL_p(500 psia)).
1 This software is equivalent to the steam table version accessible in Matlab. The software
library uses new industrial formulation for steam table calculations.
