Descnptionof the Moderator Systems for the ESS Project

Ris0-R-9O8(EN)

. DK9600126 Descnptionof the Moderator Systems for the ESS Project

Karsten Stendal

Ris0 National Laboratory, Roskilde, Denmark October 1996 i o m 0 1 Description of the Moderator Systems for the ESS Project

Karsten Stendal

Ris0 National Laboratory, Roskilde, Denmark October 1996 Abstract This paper describes a suggestion for arranging the Cold Neutron Sources for the two targets in the ESS project.(European Spallation Source). The suggestion is based upon the technique used in the existing cold neutron sources at Ris0 in Denmark and HMI and Geestacht in Germany. As moderating media all of them use H2 in supercritical condition, circulated by blowers, and the safety of the systems is based upon the triple-containment philosophy. This seems to be the most convenient principle to use near the ESS targets, as it gives a larger degree of freedom in arranging these sources and connecting the pipes to the chamber, especially because of the limited space and relatively complicated access to the target. The moderator chambers have been designed by KFA, Ju'lich and the other components and arrangements by Ris0. The price calculations used for the ESS project are based upon the proposed arrangement.

ISBN 87-550-2198-0 ISSN 0106-2840

Grafisk Service, Ris0, 1996 Contents

Foreword 4

1 Short Description and Data 5

2 Data for the Cold Neutron Source 6

3 Cold Neutron Source for ESS Project 7 3.1 General Technical Description 7 3.2 Components Near the Target 9 3.3 Cooling Plant 9 3.4 Hydrogen Circuit 11 3.5 Hydrogen Buffers and Supply System 11 3.6 Standby Cooling System 12 3.7 Vacuum Systems 13 3.8 Helium Protection Systems 14 3.9 Auxiliary Systems 75 3.10 Exhaust Pipe Systems 16 3.11 Compressed Air System 17 3.12 Lifting Equipment (Cranes) 17 3.13 Electric Arrangements 18 3.14 Arrangements for Measuring, Controlling and Monitoring 19 3.15 Qualification of the Equipment 21 3.16 Buildings 21 3.17 H2O Moderators - Operating at Room Temperature 22

4 Figures 22 4.1 Cost Estimates 23 4.2 Manpower Estimates and Calculations 23

Detail Calculations of Various Parts 26

Ris0-R-9O8(EN) Foreword

The intention of this report is to describe the arrangement of the Cold Neutron Sources for the ESS-project. The description is not given in minute detail, but only at a level where understanding of the function of the plant should give no problems. The layout of the arrangement includes two hydrogencooled moderators at each target, i.e. four separate moderating circuits with an estimated cooling capacity of 7.5 kW each. The precise cooling capacity required cannot be concluded before the detailed calculations are performed during the detailed design phase, but if the power is changed, f.ex. +/-30% of the estimated level, it will hardly influence the total price of the plant, as most of the expenses are used for manpower, buildings and back-up machinery more or less indepen- dently of the actual cooling capacity on the respective moderator chambers.

The arrangements of the H2O moderators for room temperature, are quite straightforward; they will be described at the end of the report and will be in- cluded in the cost estimate.

Ris0-R-9O8(EN) 1 Short Description and Data

A cold neutron source is an experimental device, which shifts the spectrum of neutrons towards longer wavelengths between 4-20 Angstr0ms. The energy of the neutrons will be between 5 meV and 0.2 meV, and the speed of the neutrons between 200 and 1000 m/s. The cold neutrons will be guided away from the moderator chamber through a beam liner to an area where they can be used for experiments. The cold neutron source described here is a hydrogen moderator chamber one filled with hydrogen at 25-35K and a pressure at approx. 15 bar. By passing through this cold moderator, the number of low-energy neutrons, well-suited for experiments, will be raised considerably. These very low temperatures are achieved by using industrial cooling plants, involving helium compressors with oil and gas coolers and a "Cold Box". This cold box contains the necessary counterflow heat exchangers and an expansion turbine. To achieve perfect isolation the cold box is evacuated. This cooling plant produces 20K cold helium which is used to cool the hydrogen in a He/H2- heat exchanger. The cooled hydrogen is circulated between the heat exchanger and moderator chamber by a blower. This so-called H2-blower is mounted in a "joint-box", together with the He/H2 heat exchanger and the necessary valves and measuring devices, and this box is also evacuated for insulation reasons. (Se figures 1 and 4) The pipe arrangements between the cold and joint boxes will in the following text be described as helium transport liners. The liners between the joint box and moderator chamber will be denoted hydrogen liners, and the liner from joint box and to the hydrogen back-up system will be called a hydrogen supply liner. In the "Hydrogen house" can be found all the devices for filling and controlling the hydrogen, and for emptying the system, if necessary. To maintain the pressure in the hydrogen system within specified limits during the wide temperature variations, a "buffer tank" is incorporated in the system. The component for cooling the moderator system in standby situation (when the helium cooling system is not operating, but the moderator chamber is heated by radiation) is placed in the standby cooling box. This arrangement is not used to produce cold neutrons, but to secure that the chamber temperature does not exceed 100°C. To achieve this the stand-by box is equipped with two sets of cooling machines and three circulation blowers, which will cool the hydrogen to a temperature of about -35 °C. In the test hall all the hydrogen-containing liners will be surrounded by a so- called "triple containment system". By the use of continuously controlled systems of H2, vacuum and He, eventual leaks will be detected immediately, and suitable countermoves can be carried out when needed.

Ris0-R-9O8(EN) 2 Data for the Cold Neutron Source

At the 1-MW target: Two H2 moderators, each with 7.5 kW cooling capacity at 25K. At the 5-MW target: Two H2 moderators, each with 7.5 kW cooling capacity at 25K.

Design data

(All pressures in this list are absolute pressures)

Hydrogen system Pressure > 13 bar Temperature > 14.2K Design pressure 20 bar

Moderator chamber Aluminium chamber (AlMg3) 150x150 mm Average thickness of hydrogen layer 50 mm Chamber wall thickness in beam directions = 3 mm

Hydrogen cooling circuit: Normal operation Operating pressure 13.9-17.3 bar Operating temperature 25 -35K Density 66 - 25 g/1 (25 - 35K) Flow approx. 4.5 1/s (0.61/s/kW) Cooling capacity 7.5 kW

Standby cooling system: Operating pressure 13.9 - 17.3 bar Inlet temp, chamber -35 °C Flow approx. 31/s

Hydrogen: Purity 99.9996 vol% H2-circuit at 25K = 1500g In hydrogen liner = 100g In buffer tank == 12000 g Buffer tank volume = 10m3 Vacuum systems: Vacuum system 1 Operating pressure <10"6mbar Vacuum system 2 Operating pressure <10~6mbar Vacuum system 3 Operating pressure < 10"6 mbar Vacuum system 4 Operating pressure < 10"' mbar Before He filling Vacuum system 5 Operating pressure < 10"' mbar Before He filling

Ris0-R-9O8(EN) Helium systems: Purity 99.998 vol% Helium system 1 Operating pressure 1.2-1.5 bar Protection gas Helium system 2 Operating pressure 1.2-1.5 bar Protection gas Helium system 3 Operating pressure 1.2-1.5 bar Protection gas Helium system 4 Operating pressure = 11 bar (high- pressure side) = 2 bar (low- pressure side)

Cryo cooling plant: Working gas Helium (Helium system 4) Purity 99.998 vol% Cooling capacity at 25K 7.5 kW Cooling of complete system 610 kW

Helium buffer tank Volume 10 m3 Operating pressure = 15 bar

In the following descriptions specific numbers on measuring points and mano- euvre valves will not be given. If this information is needed it can be found in: Reports for safety analyses for GKSS and HMI (Ris0 November 1984), which also include detailed diagrams. For the ESS project these details and diagrams are expected to be produced during the detailed design phase. The principles for this type of Cold Neutron Source, are based upon three existing and running sources: at the DR3 reactor at Ris0, in operation since 1975, and at GKSS, Geestacht and HMI, Berlin, in operation since 1988.

3 Cold Neutron Source for ESS Project

3.1 General Technical Description In principle, the cold neutron source is a chamber cooled by a deep-cold hydrogen flow and placed near the spallation target. The hydrogen flow serves as moderator for the neutrons produced in the target, and as cooling media for the walls in the chamber, which is heated by the radiation, (figure no. 1). Neutrons passing the moderator transfer their energy to the hydrogen as heat, and they leave the moderator with a considerable lower energy. These so-called cold neutrons are guided to the experiments outside the shielding via the beam liners. The cold neutron source is basically arranged by means of two separate circuits, (figure no. 1). The first is the hydrogen circuit. In operation, as already

Ris0-R-9O8(EN) described, deeply cooled hydrogen will circulate through the moderator chamber, and the absorbed heat will be transferred away through the heat exchanger to the helium circuit in the cryo cooling plant. The hydrogen is circulated by one of the two blowers. Heat exchanger and blowers are placed in the so-called joint box, which for isolation reasons is evacuated. (The helium-circuit in the cryo cooling plant will be described elsewhere.)

The basic safety principles in a cold neutron source are • To prevent atmospheric air from penetrating the hydrogen system • To prevent hydrogen from leaking out of the system

By surrounding the cooled parts of the hydrogen circuit with three containment barriers in the regions behind the shielding and in the target hall, these basic safety principles are satisfied. The first containment round the hydrogen system is formed by the walls and pipes in the hydrogen circuit. The second containment is the walls forming the vacuum system isolating the H2-system, and the third containment is a helium system, completely surrounding the vacuum containment (triple-containment system). Hydrogen when isolated is completely harmless. Hazards first arise when oxygen is also present.

The hydrogen/oxygen process may arise in two ways • If some source of ignition is present, the elements can combine exothermi- cally to form water • By irradiation of oxygen at cryogenic temperatures, ozone and, if nitrogen is present too, possible oxides and ozonides of nitrogen can be produced; they can decompose explosively and may initiate a hydrogen/oxygen reaction

The basic principle for securing the safety of a cold neutron source is to preclu- de any possibility that air can enter either the hydrogen system or regions of the equipment containing hydrogen, especially at cryogenic temperatures and in fields of high radiation. The hydrogen in the moderator circuit is under a pressure of approx. 15 bar, and the moderator temperature is approx. 25K at a cooling capacity of 7.5 kW. On the temperature/enthalpy diagram in figure 2, it can be seen that the hydrogen at a pressure > 13 bar and 14.2K will be in the gaseous phase (supercritical). The supercritical system offers some advantages over other systems for two reasons: no phase change takes place, and the density of the hydrogen changes with the temperature. The absence of phase change also admits standby cooling of the moderators (see below) just by circulating the hydrogen. Furthermore, it may be possible to optimise the neutron gain by adjusting the temperature. In figure 3 the density-temperature relationship can be seen in the region between 25 - 35K and a pressure of 16 bar.

(Se figure 4 and 5)

The cold box in the cooling circuit is connected to the joint box by the helium liner. The joint box contains the hydrogen/helium heat exchanger, two hydrogen circulating blowers, temperature measurement gauges, cryo valves for the hydrogen circuit, vacuum valves and ion-getter pumps for the vacuum containment, and cooling equipment for the hydrogen blowers.

Ris0-R-9O8(EN) The vacuum box contains the necessary pumps and instrumentation for estab- lishing vacuum in the isolating systems. The moderator chamber is connected to the joint box by the hydrogen liner. The cold box, vacuum box, joint box and relief box are placed in the target hall. The hydrogen buffer tanks, hydrogen supply system (hydrogen house), standby cooling system and helium buffer tanks are placed in open air. The compressor and oil filter system are placed in a separate building, mostly for sound-isolating reasons.

3.2 Components Near the Target (See figure 6)

The components near the target are: • Moderator chamber • Vacuum chamber • Helium chamber • Equipment for water-cooling helium chamber • Part of the hydrogen liner

The moderators are placed in wing position over and under the target construction, (see figure 7) and the connecting hydrogen liners lead upwards to a coupling joint on top of the shielding. This is the situation for both targets (1 and 5 MW). The moderator chamber is made of aluminium (AlMg3), and has the inside dimensions of 150xl50mm; the thickness of the hydrogen layer is 50 mm. The wall thickness of the chamber in the beam direction is 3 mm (see figure 8).

The volumes are: Hydrogen volume = 1080 cm3 AlMg3-volume = 380 cm3

Hydrogen liners: The hydrogen liner connects the moderator unit with the joint box. This liner is designed in two sections, divided by a coupling unit placed on top of the shielding. The section from the moderator and close to the coupling is made of AlMg3. Near the coupling the material is changed by a friction weld to stainless steel, which is used for the rest of the liner constructions. This is valid for all three containments. The coupling unit on top of the shielding will ease the handling and exchange of the moderator. On the moderator chamber outlet pipe an arrangement of thermo couples (four plus reserves) is placed. On the outside of the vacuum chamber three (plus reserves) thermocouples are placed. The function of the measuring components is described later.

3.3 Cooling Plant The hydrogen circulating through the moderator chamber is heated by nuclear radiation from the target and by heat transfer from the surroundings. Because of this a continuous cooling of the hydrogen is necessary. As seen at figure 4 the cooling is performed by heat exchanging in a hydrogen/helium heat exchanger

Ris0-R-9O8(EN) in the joint box. Hereby the heat is transferred to the helium gas in the cooling plant. This cooling plant is a 100% industrial plant. The heat exchanger is a plate/fin construction in aluminium and operates after the countercurrent principle. The exchanger is placed in the joint box in vacuum system 2. The cooling capacity in the exchanger is 7.5 kW, and the heat comes from: • Nuclear heating of moderator chamber and liner • Nuclear heating of the hydrogen • Heat from the hydrogen blowers • Heat transfer along the hydrogen liner

The hydrogen is cooled from 26 to 24K in the heat exchanger. This corresponds with the hydrogen flow of approx. 3 1/s. The helium in the heat exchanger is heated from 19 to 25K. The inlet and outlet temperatures in the heat exchanger are measured. The cold box in the cooling plant is placed close to the joint box to keep the more complicated liners as short as possible. Joint box and cold box are connected by the helium liner, and this is insulated by vacuum system 3. The cold box is connected to the helium compressor in the compressor house by the helium supply liner. This helium system (no. 5) is connected to the helium buffer tank, placed in open air. In the cooling plant helium at low pressure (1-3 bar) and room temperature is compressed to max. 19 bar by an oil-lubricated screw compressor. The heat from the compression is removed by an external water-cooled loop. The compressed and oil-free helium is guided to the cold box by the helium supply liner. Here the helium is cooled in a counterflow heat exchanger before it passes an expansion turbine. The turbine is a small single-stage centripetal turbine that drives a directly coupled single-stage centrifugal brake compressor. The turbine is equipped with self-acting gas bearings, supplemented by auxiliary magnetic bearings for start-up. The energy which the turbine extracts from the helium is transferred to the brake compressor circuit, and from here transferred as heat to the cooling water in the helium gas/water heat exchanger. The turbine rotates at approximately 200,000 RPM. This turbine does not require maintenance and is in many ways comparable to the turbo chargers, which are becoming more and more standard equipment in automobile engines. By this expansion the temperature decreases to 19K. Finally, the helium is guided to the heat exchanger in the joint box, where it is heated by the hydrogen in the moderator circuit, after which it flows back to the cold box, through the counterflow heat exchanger in the cold box, and then back to the compressor. The heat developed in the compressor side of the expansion turbine is removed by an external water-cooled loop. The capacity of the cooling plant can be adjusted to achieve a certain temperature in the hydrogen down to 25K. If the heating of the hydrogen decreases f.ex. if the spallation process is stopped, the temperature will drop below 25K. The cooling plant will therefore be stopped when the temperature in the hydrogen reaches 19K to prevent the hydrogen from freezing solid. The helium circuit itself is adjusted so temperatures below ]5K are not possible. The cold parts of the components in the cold box are isolated to a very high degree against thermal radiation by using vacuum insulation and by wrapping several layers of aluminium/mylar foils around the components. In the cold box arrangements are made for measuring, controlling, and manoevering the valves in the cold box, so that a compressed air supply is necessary.

10 Ris0-R-9O8(EN) The three vacuum systems 1, 2 and 3 which insulate the moderator/liner, joint box and cold box are supported by the vacuum box, which contains pumps for all three systems. These systems can be evacuated separately or together, and they can be leak tested from the box as well. During operation vacuum systems 1 and 2 are pumped by two ion-getter pumps, placed in the joint box.

3.4 Hydrogen Circuit The purpose of the hydrogen circuit is to supply the moderator chamber with cold hydrogen and remove the heat developed in the chamber. The moderator chamber is connected to the joint box by the hydrogen liner. The liner section between the moderator chamber and coupling unit is partly made of aluminium (AlMg3), and partly of stainless steel. This liner goes through the shielding, and the coupling unit is placed on top of the shielding vertical over the target as already described (see figure 5). The hydrogen pipes inside the hydrogen liner connects the moderator chamber with the hydrogen pipes in the joint box. The vacuum system around these hydrogen pipes is named vacuum system 1, and the respective helium blanket surrounding this system is named helium 1, whereby the necessary triple- containment system is fulfilled in this section. Hydrogen is circulated between the moderator chamber and heat exchanger at 15 bar and 25K, by one of the two hydrogen blowers (H-bl.l or H-bl.2). The blowers act as standby for each other, in the way that only one is necessary for a satisfying circulation, and in case of breakdown of the blower in operation, the other will start up in few seconds. The switch from one blower to the other will be initiated by the temperature rise at the moderator chamber (to 100K). The original blower will by this changeover be stopped and the valve behind it will be closed, or alternatively, the blowers can be mounted in a series connection. Flow through the standby circuit outside the target hall will be prevented by the valve arrangement and standby box.

3.5 Hydrogen Buffers and Supply System The hydrogen buffer tanks and supply system are installed to limit pressure changes between certain values during temperature changes in the system, and to supply the system with clean hydrogen. The hydrogen-filling system is arranged in the hydrogen house, and connected to the joint box by the supply liner. The part of this liner passing through the target hall is constructed after the "triple containment" concept. The vacuum containment of this liner is part of vacuum system 2, which starts in the joint box, and the helium containment is part of helium system 2, which includes the joint box. The triple-containment system around the supply liner ends outside the target hall in the relief box. The 10 m3 hydrogen buffer tank is connected to the system via the valve arrangement in the hydrogen house. This buffer tank contains approx. 89% of the hydrogen in the system during normal operation, and approx. 99% during the standby cooling operation. Based on operating conditions and the surrounding temperature, the pressure in the hydrogen system will vary within the range 13.9 and 17.3 bar. The original pressure in the system from filling will be approximately 17 bar, and the pressure will sink 1.7 bar when going to cryo

Ris0-R-9O8(EN) 11 conditions in the moderator circuit. The pressure changes in relation to the outdoor temperatures will be approx. 0.056 bar/°C. The check valves in the hydrogen system can be leak tested by combining the valve settings in the hydrogen house during temperature changes in the moderator circuit. In the hydrogen house, the hydrogen supply liner to the buffer tank is equipped with a bursting dish that opens at a pressure difference at 18 bar, and relie- ves the hydrogen through a safety valve. This safety valve is adjusted to an opening pressure of 15 bar, and a valve is placed in the pipe length between the bursting dish and safety valve, to be used when testing the safety valve. In this position an alarm is also set in place, which signals when the pressure in this position exceeds 1.1 bar due to leaks in the bursting dish arrangement. An alarm is activated when the hydrogen pressure exceeds 17.3 bar. These safety and check systems are doubled. In the hydrogen house a stationary vacuum pump with cooling trap and ap- propriate valve arrangement is connected to the hydrogen supply system. The hydrogen supply system is supported by two hydrogen bottles placed outside the hydrogen house. A system of valves, manometers, pressure regula- tors and safety valves is arranged between the bottles and hydrogen system. The volume of the buffers and the leak of the complete system are dimensioned so only two to four refill procedures per year will be sufficient to compensate for losses due to hydrogen diffusion and opening of the system for repairs. To be able to test the hydrogen system for leaks, after repair and changes of bottles, blowers etc., a helium bottle with valves and necessary safety equipment, is connected to the hydrogen system. The helium is used for testing and sluicing . The hydrogen house itself is of light-weight construction with heating and ventilation. The different relief valves in the hydrogen house are connected to a common pipe leading to a ventilation chimney outside the house. The venting pipes connected to manual valves, are equipped with a common flame trap. The safety valves must not be connected to any component that might cause pressure drops.

3.6 Standby Cooling System The purpose of the standby cooling system is to cool the moderator chamber and hydrogen when the helium cryo cooling plant is not running. The system consists of three blowers and two freon coolers (or similar units), in series. All components are placed on a common frame (box). The standby circuit is started automatically by the control system, and when running the situation is (see figure 9).

In the joint box: • One of the two blowers remains running • The hydrogen/helium heat exchanger is bypassed

In the standby cooling box: • The inlet valves to the "box" are opened • Two of the three hydrogen blowers are running • One of the two freon coolers is running, the other is in standby position

12 Ris0-R-9O8(EN) In the standby cooling situation the cooled hydrogen flows through the moderator chamber, through the hydrogen liner, through the joint box arrangement and via the hydrogen supply liner through the standby cooling unit placed in the hydrogen house. The signal to start the standby cooling is given when the temperature at the moderator chamber reaches -35°C, measured by the thermocouples mounted at the chamber, and in a two out of three signal configuration.

Emergency Precautions Against Overheating the Chamber If the standby cooling fails, an emergency procedure is started when the temperature reaches 95°C at the moderator chamber, measured by a two out of three configuration by the thermocouples at the chamber. This means that the operation of the target must be stopped and the emergency cooling performed until the temperature lies below a safe level. The pressure in the moderating circuit (not in the buffers) is lowered to 1.5 bar by a combination of the valves in the hydrogen house. Hereby the stress loads at the moderator chamber are considerably lowered and the chamber can withstand temperatures of over 200°C without problems. To cool the chamber vacuum containment no.l (around the chamber) is floated with helium, (backfilling), whereby the heat can be removed via convection through the helium. If the temperature rises above 200°C, an additional cooling procedure is in- troduced. Again via the valve arrangement in the hydrogen house, helium is floated directly into the hydrogen circuit, through the moderator chamber and to the ventilation chimney to open air (bleeding). Through the dimensioning of the helium pipes this arrangement can produce a safe cooling of the moderator chamber for up to ten hours. In this procedure the helium in the buffer tank is used. In case the operation of the target is continued beyond these emergency limits, it will come to a melting of the moderator chamber near the target, but this event will not endanger the target construction, or lead to any other hazards, except those happening to the moderator in-pile unit itself.

3.7 Vacuum Systems For the cold components in the hydrogen circuit and the cold part of the helium circuit in the cold box, vacuum is used as thermal isolation. The vacuum which surrounds the moderator chamber and the hydrogen liner is named vacuum system no. 1. The vacuum in the joint box is named vacuum system no. 2, and the vacuum in the helium liner and the cold box is called vacuum system no. 3. Besides these three vacuum systems there are two very small systems named vacuum systems 4 and 5. They are situated between the two vacuum valves in the suction liners from vacuum systems 1 and 2 and to the vacuum box. When the cold neutron source is in operation, systems 4 and 5 are closed with the vacuum valves and then filled with helium. This is done to conform to the triple-containment safety philosophy during operation. In this situation, vacuum systems 1 and 2 are pumped by the two ion-getter pumps, one in each system. On the suction piping from all three vacuum systems 1, 2 and 3, there are connections to helium leek test equipment.

Ris0-R-9O8(EN) 13 The vacuum box is equipped with three turbo molecular pumps and two prime pumps. During normal operation of the neutron source, vacuum system no. 3 (the cold box) is continuously pumped by one of the turbo molecular pumps and a prime pump. Vacuum systems 1 and 2 are both equipped with instruments for warning and shut down of the complete cooling systems. At 5xlO"3 mbar an alarm is trigge- red in a one out of three configuration of measurements, and at 0.1 mbar the cooling plant is shut down by a two out of three configuration. At a pressure > 5xl0'5 mbar, the ion-getter pumps are stopped. Furthermore, both systems will be equipped with three pressure switches, which, for protection of the neutron source, will shut down the spallation process and perform a pressure release of the vacuum systems at a pressure of 1.6 bar. Vacuum systems 4 and 5 are equipped only with a pressure gauge, releasing an alarm at pressures > 0.1 mbar. The following arguments are the reasons for splitting the vacuum into three separate systems: • A possible leak is easier to detect • Only one system has to be opened, when f.ex. a hydrogen blower is changed • Vacuum system 3 is integrated in the helium cooling plant, which is a separate supply system

At a quick pressure increase in vacuum system 1 (approx. 2 bar, for example in case of a large leak in the hydrogen system), the pressure will be released to vacuum system 2. For this purpose a bursting disk is mounted between vacuum systems 1 and 2. This disk will open at a pressure difference of 2 bar. Also vacuum system 2 is protected by a bursting disk, which also opens at a pressure difference of 2 bar. The pressure release from vacuum system 2 enters the helium system 3 in the relief box. This box is equipped with two safety valves that open at max. 2 bar.

3.8 Helium Protection Systems The safety philosophy of the triple-containment systems is that all hydrogen- containing pipes in the target hall are surrounded by a vacuum system, which again is contained in a helium protection gas system with pressure higher that the atmospheric pressure on the outside (helium system pressure =1.3 bar). The helium containment has been divided into sections to make it simpler to re-establish the systems after reparations are made, and to ease the localisation of leaks that might eventually develop. Helium system 1 surrounds vacuum system 1, helium system 2 surrounds vacuum system 2, and helium system 3 covers the bursting disk from vacuum system 2 in the relief box. In case of a leak in helium system 1, 2 or 3, the respective pressure will drop. When the pressure drops to 1.2 bar an alarm is given (after a 1 out of 3 relay combination) and at 1.1 bar (2 out of 3 combinations) the cryo cooling plant is stopped. The three helium systems are supplied with the gas from a single common helium system; this common system is supplied from two helium bottles with reduction valves to the system pressure used of 1.3 bar. Before the helium systems are filled, they are evacuated with the vacuum pumping systems in the vacuum box.

14 Ris0-R-9O8(EN) The three systems are protected against overpressure by safety valves, one for each system, and adjusted for a maximum pressure of 2.0 bar.

3.9 Auxiliary Systems The auxiliary systems include cooling systems, exhaust systems and compressed air systems.

Cooling Machines As described in an earlier chapter, the heat from the radiation on the moderator chamber in a standby situation, will be removed by a Ha/freon (or similar) heat exchanger, and cooled by connected cooling machinery. The heat from the radiation (and the removed energy) will be max. 7.5 kW, and the hydrogen will be cooled to -35°C, as a minimum.

The two H2/freon heat exchangers with their respective cooling machinery in the standby cooling box, are arranged in series, and can each remove the 7.5 kW necessary. AH other components in these freon cooling circuits are arranged in the standby box, except the condensors which have to be placed in open air, f.ex. on the roof of the hydrogen houses.

Cooling of the Vacuum- and Helium Chambers The vacuum chamber will be cooled by conducting the heat through the helium layer. To keep the temperature below 100°C, the split between helium and vacuum chambers must be smaller than 0.25 mm. The nuclear heating from the neutron window on the vacuum chamber will be conducted away through the aluminium wall itself and through the helium 1 system. Finally, the transferred heat will be taken away through the water system circulating on the outside of the helium chamber. If the temperature exceeds 100°C on the vacuum chamber, an alarm is started through a one out of three combination of the thermocouples on the chamber wall. The heat conducted from vacuum chamber to helium chamber as well as the heat developed in the helium chamber are removed by the water-cooling coil on the outside of the helium chamber. The circuit for this system is a straightforward cooling water system, able to remove approximately 10 kW pr. in-pile unit (it is a common circuit pr. target, cooling the two hydrogen moderators, and the two KbO-moderators, i.e. 4 units pr. target.). The circuit consists of two pumps and two heat exchangers in a parallel arrangement together with a max. pressure device with buffer and a ION-exchanger-filter (see diagram in figure 14).

Compressor Cooling Systems These systems remove heat from both oil and helium following the compression. Through a cooling tower outside the compressor house, the heat is transferred to the environment with a capacity of approximately 600 kW pr. cold neutron source circuit. The cooling tower is of the irrigation type, which is a pipe bundle heat exchanger sprinkled with water, being able to cool the media to temperatures below the surroundings. (As an alternative, this cooling system could be connected to the main cooling system for the targets if the temperature levels are

Ris0-R-9O8(EN) 15 adequate.) Freezing of the circuit water is prevented by coils of electric heating cables on the pipe sections passing through open spaces.

Cooling Circuits for Hydrogen Blowers and Expansion Turbines The cooling circuit for the expansion turbine must take away the heat developed in the braking process of the turbine. The amount of heat taken away de- pends upon the arrangement of the turbine: one or two steps, with or without precooling with nitrogen. But the maximum cooling power needed will be approx. 40 kW and can be produced by a separate cooling plant, or through the main cooling circuit. The purpose of the hydrogen blower cooling is to remove the heat from the motor resistance in these blowers. This is done by two separate (one pr. blower) coolers with water circulation, in which the blower housings are mounted in a way which fulfils the triple-containment demands. The cooling capacity is far less than 1 kW pr. blower, and cooling has been performed with separate water circuits cooled by small freon compressors. To protect the hydrogen blowers against overheating the cooling circuits for the blowers are equipped with flow alarms, which switches off the running blower at a cooling water flow less than 100 1/h. Shifting to the other blower, as already described, will happen when the hydrogen temperature in the moderator chamber exceeds 100K. If the second blower also drops out due to lack of cooling, the cooling of the chamber will be taken over by the standby cooling system at -35°C.

3.10 Exhaust Pipe Systems These pipe systems have the task to discharge gases from the hydrogen containing system, the vacuum systems and the helium protection gas systems. Each of the four cold neutron source systems are equipped with these exhaust pipes at the following positions: • Exhaust pipe from the hydrogen house • Exhaust pipe from the safety valves from the relief box • Exhaust pipe from the safety valve on the standby cooling box • Exhaust from the vacuum pumps in the vacuum box • Exhaust from helium systems 1 and 2

The exhaust pipe from the hydrogen house discharges the exhaust from the hydrogen system and from the helium system in the hydrogen house. The "chimney" on the outside of the target hall wall receives the exhaust from hydrogen relief in the vacuum systems 1 and 2 passing the respective bursting disks into helium system 2. From here the hydrogen/helium mixture passes the two safety valves to the exhaust pipe (chimney). The exhaust pipe from the standby cooling box discharges the exhaust from the hydrogen system during the bleeding (emergency) situation, when flushing with helium. Exhaust pipes from the target hall to chimney handle the exhausts from the vacuum pumps in the vacuum box and from the helium systems 1 and 2. Of safety reasons all the manually operated valves are connected to the chimney via a flame trap. Pipes with safety functions (exhaust from safety valves) bypass the flame traps to limit the pressure rise on the way to the chimney.

16 Ris0-R-9O8(EN) The chimney outside the target hall receives the relieved gases from helium systems 1, 2 and 3, and the exhaust from vacuum systems 1, 2 and 3. In certain situations small amounts of hydrogen can appear, for example during a hydrogen leak in vacuum system 1 or 2 when pumping down. According to the system layout it is possible to evacuate vacuum systems 1 and 2 with the turbo molecular pumps, and a large hydrogen release might take place with larger leaks between the hydrogen and vacuum systems. This is prevented by closing the two sets of vacuum valves from vacuum systems 1 and 2 to the vacuum box at 0.1 mbar. Hereby, the hydrogen release to the chimney will be on the order of 1 g, which is harmless. In the case of a break in the bursting disk in the relief box a mixture of helium and hydrogen will flow to the chimney through the safety valves. A break of the bursting disk is always combined with a pressure rise in the relief box and will be detected with the pressure gauges in the box.

3.11 Compressed Air System This system must supply all pneumatically actuated valves in the Cold Neutron Source (CNS) system with sufficient, dry compressed air at 6 to 8 bar, to be used for: • Valves in the hydrogen house • Valves in the compressor house • Valves in the cold box • Valves in the vacuum box • Valves in the standby cooling box • Valves on the control board

To secure a troublefree function of the compresse-air operated valves with safety functions, the supply for these valves will be redundant. This redundancy includes two parallel supply liners, each equipped with non-return valves, a pressure vessel and an alarm system.

3.12 Lifting Equipment (Cranes) The maximum weight of the units in the cold neutron source system will be under 8 to 9 tons (not including the shielding above the target).

The following cranes will be needed: • Compressor hall. A 10-ton travelling crane to shift compressors and filter units • Test hall/workshop. A 10-ton travelling crane • The target hall will be equipped with more than sufficient crane capacity for the CNS units in the hall

Special tools have to be designed for the respective units (lifting gear etc.). For the in-pile part a shielded "bottle" or robot must be designed, as it will be needed when removing active, used components.

Ris0-R-9O8(EN) 17 3.13 Electric Arrangements The demands below must be followed when arranging the layout for the power supply for the Cold Neutron Source. The CNS receives power from same source (grid) as the spallation source. If the supply to the CNS stops, the spallation process must stop too. The helium cooling plant starts up automatically after a power dropout. Standby cooling system must be supplied by an emergency grid.

The following power supply systems are needed: • Main grid supply • Supply from emergency grid • Safety system for instrumentation, alarms and absolute vital components

Main Gid Supply The following components are connected to the main grid: • Compressor units • Cold box • Cooling towers and circuits with pumps • Vacuum systems • Cooling box for H2 in-pile parts and H^O-moderators • Control and regulations • Standard electrical installations for hydrogen house, compressor hall, work- shops etc.

Emergency Grid This system will most likely be part of the emergency system for the spallation source.

The following units must be supplied from this grid: • Standby cooling • Circulation blowers • Circulation pumps for critical circuits

Safety Supply (non-breakable Circuit) The non-breakable power supply consists of redundant DC and AC supply systems. The DC system is composed of two rectifier units and two batteries, which are coupled to two separate DC circuits.

On these, two 24-V DC power circuits are coupled: • Measure, control and monitoring systems • All valves

Besides this, the valves for the helium flushing of the moderator chamber (bleeding) are coupled to an extra safety supply, namely a separate battery with minimum 10 hours supply and a separate rectifier. The 220-V AC safety supply system consists of a frequency converter supplied from the 24-V DC circuit - and a bypass arrangement. To this AC circuit the following are coupled:

Ris0-R-9O8(EN) • The hydrogen blowers for the standby cooling system • Monitors and printers • Measurement and control arrangements

The systems must be protected with adequate ground connections and lightning protections. These arrangements are copied from reactor installations. Other demands may arise during the detailed design of the ESS plant.

3.14 Arrangements for Measuring, Controlling and Monitoring The cold neutron source is manually operated until it is in cryo condition, and then it is operated automatically. To secure this automatic operation, devices for measuring, controlling and monitoring continuously review the condition of the plant, reporting if the prescribed operational data are respected, that irregularities or drop-outs of components are recorded, and that the situation is kept within acceptable limits. The central supervision of the plant is carried out via the control board in the target hall. The control board includes the following devices: • Instruments for various measuring points • Switch panel for measuring, controlling and monitoring the devices • Computer with processor, keyboard, screen and printer • Communication

As the control board is not permanently manned, the condition reports and the most important data and the alarms are transmitted to the central control room for the complete spallation plant. From here, more detailed surveillance can also be performed, when required.

Measurement Device The parameters measured are: • Temperature • Pressure • Flow

The information sent to the control board is picked up by measuring heads, then transformed to currents between 0-20 ma or voltages between 0-10 V, then pro- cessed by the computer and recorded. Measurements which are used only for surveillance and monitoring are transferred via binary relay control. For safety reasons some of the measurements are performed via three separate circuits and used in a "one out of three", or a "two out of three" combination, to be used in certain alarm combinations and switch manoeuvres. Of these can be mentioned: • Stop of the complete spallation process • Stop of the helium cooling plant • Shift of the hydrogen blower in operation • Start of the standby cooling plant • Backfilling • Bleeding

Ris0-R-9O8(EN) 19 For temperature measurements thermocouples and resistance thermometers with matching transformers are used. For pressure measurements there are two regions to cover: positive pressure systems, and systems with vacuum. The positive pressures are measured with measure heads and transformers, with pressure switches or with manometers. In vacuum systems heat conducting vacuum meters or cold cathode ionisation vacuum meters are used. Flow meters with signal transformers control/survey the flow velocities. All remote-controlled valves and various manual adjustment arrangements are equipped with position switches, and arrangements for variable adjustments are, where needed, equipped with position indicators, f.ex. potentiometers.

Control Arrangements The control arrangements for CNS are dimensioned so the prescribed process data can always be respected. The CNS is manually operated till it reaches cryo conditions, and then it is operated automatically. As a control system, one that is cabled and commercially available is used.

Monitoring The monitoring of the CNS is arranged to permit permanent monitoring even with an unmanned control board. Complete reports on the measurements and manoeuvres are automatically recorded, and the most important single measurements are shown in the central control room for the spallation plant. Furthermore, specific measurements can be ordered from the central control room via the monitor.

Among these arrangements are: • State diagram with reports from all remote controlled components. Ana- logue instruments for measurements, and lamp signals for alarm devices • Signal devices • Terminals in the CNS control board • Terminals in the Spallation Source central control room

The state diagram on screen delivers constantly a view over the condition of the CNS. The operational conditions of components and the measured values are continuously shown. Disturbances and problems in the process are advised optically by means of lamp signals and with the aid of acoustic alarms. The monitoring system works after the following principles. New values of measurements, out of limits, are announced with rapidly blin- king lamps. These signals are replied (confirmed), and the lamp shifts to con- stant light as long as the measurement remains outside the set limits. When the value of the measured parameter is adjusted back inside the set limits, the lamp blinks slowly and turns off. The computer of the CNS includes a logging device and a registering system. The computer handles both analogue and binary digit signals. Data are pre- sented on the coupled printer when requested or in pre-set time intervals. Disturbances and manoeuvres with the systems are recorded automatically.

20 Ris0-R-9O8(EN) The computer serves furthermore as support for the operators when running the system manually by delivering information and checking if pre-set limits are respected.

Safety Protection of the CNS This is primary the total cabled control arrangement that operates during alarm situations when two out of three signals at marginal values will shut down the complete plant.

3.15 Qualification of the Equipment Components in the measuring, controlling and monitoring arrangement are standard equipment used in conventional plants.

3.16 Buildings The complete layout of the CNS arrangement can be seen in figure 5, which also shows the required buildings and their sizes. On the suggested plan view the following buildings will be needed specifically for the CNS: • Compressor hall 360 m2 • Workshop/test hall 360 m2 • Office building, with bath rooms • Toilet facilities and meeting room 200 m2 • Two hydrogen houses, 2x40 m2 • Foundations for two cooling towers • Foundations for 8 buffer tanks • Roofing over gas supply and outdoor storage • Garages • Roadway and flagging etc.

Furthermore, approximately 300 m2 of the floor on top of the beam shielding in each target hall will be occupied by CNS components. Reservations are made in the layout for areas to be used for later expansion of the CNS plant, or for supply systems for eventual latercoming tnuon target facilities All the components/units in the respective CNS circuits are connected with pipelines and electric cables. Furthermore, the control/safety system is a 100% cabled system. Joint box, cold box, vacuum box and control panel are placed in the target hall, close to the users and test facilities. The units are arranged with respect to easy access for repair and maintenance. The hydrogen liners (triple-containment liners) from moderator to joint box are divided in two sections, connected with a coupling unit on top of the shielding arrangement. This unit is designed to provide as conveniently as possible an exchange of the in-pile part, which has to be performed at regular intervals. The joint box and relief box are connected via the hydrogen supply liner (triple-containment liner). The relief box is mounted on the target hall wall, with the exhaust pipe (chimney) to the atmosphere placed outside the hall. The standby cooling unit is placed in the hydrogen house, and is connected to the relief box with two hydrogen pipes (approx.: 030 mm isolated with mineral mats and aluminium foil).

Ris0-R-9O8(EN) 21 The joint and cold boxes are connected via the helium liner, which is a double system liner (helium pipes in a vacuum isolation system). The cold box is connected to the compressor with the helium supply liners, which are isolated with normal isolating mats and aluminium plates. The compressor hall and workshop are arranged with crane facilities for maintenance and exchange of units. The hydrogen house contains all the filling arrangements for the hydrogen system and the standby cooling system. For safety reasons this building must be well ventilated and of a light-weight construction.

3.17 H2O Moderators - Operating at Room Temperature These moderators and the supply systems behind them are quite simple, compa- red to the cryo-cooled hydrogen moderators. The positions of the moderator chambers can be seen in figure 7, and the construction of the chambers is comparable to the chamber shown in figure 8. The H2O-cooled chambers will ope- rate at a pressure of only a few bar, however. These moderators will employ only a water cooling system, no vacuum and helium containments. A suggestion for the cooling water system can be seen in figure 14, and this system will cool both the H2O moderators, and the vacuum and helium containments in front of the in-pile parts for the hydrogen moderators.

4 Figures

No. 1: Helium and hydrogen circuits No. 2: Temperature/entropy chart for hydrogen No. 3: Density/temperature diagram for hydrogen No. 4: Diagram for the cold neutron source No. 5: Arrangement for the complete supply system No. 6: Arrangement in the target hall No. 7: Arrangement of moderators and target No. 8: Moderator chamber No. 9: Diagram for the standby situation No. 10: Diagram for the back-filling situation No. 11: Diagram for the bleeding situation No. 12: ESS-moderator department organisation No. 13: Time schedule for moderator department No. 14: Water cooling systems for H2 in-pile parts and HaO-moderators

22 Ris0-R-9O8(EN) 4.1 Cost Estimates These calculations are organised in following way: • Estimates of manpower involved from ESS staff, and related expenses • Hardware expenses pr. moderator circuit • Hardware expenses for equipment pr. target unit • Hardware expenses, common installations for the complete system • Answer and final remarks

4.2 Manpower Estimates and Calculations Se figure 12: ESS moderator department organisation, and figure 13: Time schedule for the moderator department. The organisation for the staff and an estimated time schedule for the design and installation phase is shown in these two figures (from year zero, till the plant is tested and running, end of year 5).

According to time schedule 114 man years Secretary and administration 10 man years Ad. hoc, external assistance 10 man years Total 134 man years

Off these man years the 82 are expected to be used of staff with academic degrees, engineers, administrators etc., and the remaining 52 man years are for skilled staff such as electromechanics, fitters and other technical staff, designers etc.

Expenses 134 man years x 46,000 ECU (figure from Lengeler) 6,164,000 ECU

Overhead: Rent of office etc., EDB machinery, Telephone, transport etc. (50%) 3,082,000 ECU External tests, inspections and advice 1,000,000 ECU Travel expenses in 5 years 500,000 ECU Documentation after final tests 250,000 ECU Total 10,996,000 ECU

Ris0-R-9O8(EN) 23 Personnel costs total 11,000,000 ECU

Hardware expenses pr. H2-moderator circuit: In Danish kroner. (DKK)

(E = Estimated, I = Offer from industry)

In pile part (moderator) 1,200,000 E/I Coupling, (in-pile part/triple liner) 400,000 ECU Triple liner, (moderator/joint box) 600,000 I Joint box 2,416,000 I/E Vacuum box, (three systems.) 664,000 I Vacuum lines, (three systems) 180,000 E Cold box, incl. expansion turbine 4,400,000 I He liner, (compressor/cold box) 600,000 I Relief box incl. frame 271,000 E Triple liner, (joint box/relief box) 600,000 I Water cooling for cold box 150,000 E Water cooling for joint box 80,000 E Compressor unit incl. sound isolation 2,200,000 I Oil filter system (He/oil). 600,000 I Cooling water connection, (compressor/tower) 30,000 E He buffer, tank and filling system 119,000 I - - , frames and connections 20,000 E Hydrogen buffer 119,000 I - - , frames and connections 20,000 E He system for joint box and vacuum box 80,000 E Hydrogen house fittings complete 805,000 E/I Standby cooling unit 492,000 E/I Control system, registration and main computer 1,800,000 E/I Connections to grids 450,000 E Outdoor arrangements 100,000 E Contingencies 500,000 E Total cost for hardware pr. circuit 18,896,000 DKK

Expenses pr. H20-moderator In-pile part with instrumentation 600,000 E Coupling, frames and suspension 200,000 E Connections to cooling circuit 50,000 E Total pr. moderator 850,000 DKK

Hardware expenses per target Cooling tower unit 760,000 I Handling robot for in pile part 1,800,000 E Crane equipment 80,000 E Shielding over target top 800,000 E Tools for maintenance 300,000 E Cooling system for the four moderators 330,000 E Total 4,070,000 DKK

Hardware, common installations for the total plant Buildings 10,030,000 I/E

24 Ris0-R-9O8(EN) Equipment for workshop, machines and test device 2,500,000 E Vehicles 400,000 E Total 12,930,000 DKK

Altogether Four times hardware for H2 moderator circuit 4 x 18,896,000 75,584,000 DKK Four H2O moderators: 4 x 850,000 3,400,000 DKK Two times hardware for target arrangement 2 x 4,070,000 8,140,000 DKK Buildings etc. 12,930,000 DKK Hardware total 100,054,000 DKK (13,800,000 (ECU)

Hardware in ECU 13,800,000 ECU Manpower 11.000.000 ECU

Moderator systems, costs alltogether 24,800,000 ECU

Exclusive: • Taxes • Costs for approvals and other authorities • Road, parking spaces and garden arrangements • Spare parts • Discounts due to multiplication of identical units

Operating costs yearly for the moderator systems Staff (see figure 12 and 13) 4 engineers 7 technicians 1 secretary Staff expenses 550,000 ECU External services 500,000 ECU Materials and spare parts 150,000 ECU Travel expenses 150,000 ECU (site dependent) In pile parts 600,000 ECU Power consumption 2,500,000 ECU Total per year 4,450,000 ECU

Ris0-R-9O8(EN) 25 Detail Calculations of Various Parts

Costs for joint box (DKK) Naked joint box construction 550,000 E Platform and frames 150,000 E Special tools 100,000 E 2 Ion-getter pumps 120,000 I 4 x 0100 VAT valves 40,000 I Remote controls for VAT valves 80,000 I 3 x solenoid DN25 24,000 I 2 x Hydrogen blowers with housing 150,000 I 4 xcryo valves 96,000 I Heat exchanger hydrogen/helium 220,000 I Measuring equipment: 18 vacuum heads 4 temperature gauges 4 x helium and 2x hydrogen pressure 6 x manual valves 300,000 1 4 cable lead through covers 160,000 I 2 coolers for hydrogen blowers 30,000 I 2 frames for blowers 16,000 I Cables to grid 30,000 E Cables to computer etc. 30,000 E Fitters and electricians 8 man months 320,000 E Total 2,416,000 DKK

Costs for vacuum box for three systems (DKK) 3 turbo molecular pumps 0100 (two small and one large flow 2 x 56,000+104,000) 216,000 1 2 prime pumps DN25, (large flow inclusive filters) 46,000 I 5 VAT valves 0100 50,000 I 11 solenoid valves 44,000 I Frame and covers 45,000 E Fittings incl. bellows 58,000 I/E 4 vacuum measuring heads 60,000 I Connections to grid and EDB 30,000 E Manifolds 35,000 E Man hours for mounting 80,000 E Total 664,000 DKK

26 Ris0-R-9O8(EN) Hardware for hydrogen house (exclusive building) Cooling trap 30,000 E Vacuum pumping equipment 50,000 I Measuring equipment 195,000 I Solenoid valves and others 200,000 I/E Fittings 40,000 E Pipes and frames 50,000 E Manpower 6 man months 240,000 E Total 805,000 DKK

Relief box Manufacture of containers 150,000 E Bursting disks 4,000 I 5x vacuum pressure measuring heads 50,000 I One solenoid valve 7,000 I Two relief valves 10,000 I Frame 20,000 E Manpower 30,000 E Total 271,000 DKK

Standby cooling unit Three hydrogen blowers 240,000 I Two cooling units incl. heat exchangers 80,000 E Hydrogen valves 32,000 I Automation 25,000 E Frames and covers 30,000 E Fittings 5,000 E Manpower 80,000 E Total 492,000 DKK

Cooling unit for cooling of H2-in-pile parts and H20-moderators pr. target 4x10 kW cooling compressors 40,000 E Heat exchangers and fittings 40,000 E Pumps 40,000 E Buffer 10,000 E Holding tank 20,000 E Ion-exchange filter with fittings and shielding 40,000 E Frame and covers 40,000 E Instrumentation 10,000 E Power connections and electronics 30,000 E Manpower 2 man months 60,000 E Total 330,000 DDK

Ris0-R-9O8(EN) 27 Buildings Compressor hall 360 m2 Workshop 360 m2 Two hydrogen houses each 40 m2 80 m2 Total 800 m2 Index 8,000 DKK/m2 gives 6,400,000 DKK

Office, bath, toilet and meeting rooms 200 m2 Index 10,000 DKK/m2 gives 2,000,000 DKK

Outdoor foundations Cooling towers 2 x 40,000 80,000 DKK Buffer tanks 8x25,000 200,000 DKK Frames and supports for pipe connections 300,000 DKK Garages and outdoor storage 200,000 DKK Contingencies 250,000 DKK

Cranes 2x10 tons (crane: 170,000, rails: 130,000) 600,000 DKK Total 10,030,000 DKK

Remarks to the costing Hardware costs 13,800,000 ECU Manpower costs 11,000,000 ECU Total 24,800,000 ECU

Exclusive.: Taxes, costs for approvals, Roads and parking arrangements.

1. Hardware costs are 75% priced from industry and 25% estimates. Man- power is historic and analogous to similar plants

2. Contingencies are very few (5%)

3. Accuracy+/-20%

4. Involved staff: 134 person years. Of these 82 man years are people with a- cademic degrees, engineers and administrators. 52 man years are skilled craftsmen, mechanics, electronics and designers

5. The price include 4 complete hydrogen-moderated Cold Neutron Sources incl.: • Buildings • Special tools for handling and maintenance • Shielding • No spare parts • No discount due to multiple identical plants

Karsten Stendal Ris0 National Laboratory Denmark

28 Ris0-R-9O8(EN) a

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Figure no. 1 Helium and hydrogen circuit. jTEMPERATURE -ENTROPY CHART; { FOR normal-HYDROGEN f TAKEN FROM NATIONAL BUREAU OF STANDARDS RESEARCH PAPER RP 1932 < (1948) BY WOOLEY, SCOTT, AND BRICK WEDDE. Fig 31.

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PA} Mec>ur« point. p-pr«wurP- e A-oiarm T—T«mp«ratura l-lndfcator. R«-Rodlotk>fl C-oofitrol. S-owftch—over

Vdvet monueL I Halium lyitwi 2 Check valve. Spdnglooded ch*ck RvmoU contrdl«d Sofvty vatv*. Prvsture reducing volv*. T«mp. mox. 35 *C. Coding of 40 kw. tu-blowtrs. Max. 35

1 1 Wotir cooBng of fn pH« parts.

Cooling of M2-bloi»n!. Ma>.3S°C-2kw. Vacuum tvrtttn S

Vocuum »v»tam 2 Rgure no.4 Diagram for Cold Neutron Source"

ess1a3 (j H2-buffer p (j H2-buffer |) (| He-buffer [) (j He-buffer |) ) 5 (| H9-buffer |) (| H7-buffer [) (J He-buffer |) (| He-buffer j) /H2-supply

S Area for / L L L L N s ^sexpansion;/,''

x / s. •• \ / N Compressor hall / N 360 m2

Test hall Workshop Store. 360m2

Office building 150m2

Figure no.5

Arrangement of 10m complete supply system.

-H-H h-r-f-f- modbyg11 for reflector cooling. Control faeuurri I Cooling tox J I bo*

Helium Coldbox Hydrogen

Control | focuurri I Cooling )ox I I box

Helium Coldbox Hydrogen

Figure no.6

10 motar. Arrangement in target hall.

| ' ' l 1 i v Rerflektor im Halbschnitt H2O moderator \dsc9estellt

Fig. no. 7 Beomliner axis

Hydro g_en_£.

• • CO

Kiloc?0 pR|-iFlu»h connection.

Compre*»Of unit

(^-butler

Stond by cooting iyt*ni

i i I i i i

max 35°C, 20kw|_|_ Cooling of compr. unit Mox temp. 35«C Copoclty 1 UH.

CM!-iyflt«m. (and component box**)

Vo-eontolnment Safety barrier He-blank*t Cooling water.

PA) M«o*ur* point P*-pr*«*urp * A»atarm S T-Temperatun-Te t l-ln

monu«l. Check vatv*. Sprfnglooded check votve. LJ Bunting dTak. Rvmote controlled vatve. WoUr cooKng lytUini Safely valve. Burwtlng diik. Prwwre reducing valve. Temp. mox. 35*C. 40 kw.

T 1— I I Wot*r cooling of in pile porte. 40kw.

I «___f ^ Figure no. 9 Diagram for To He—supply. Cold Neutron Source. Stand by situation.

ess2a3 »Q—4Fluth connection.

_ Comprttfor unH.

Hj-butfw

Cooling tomr.

Cooling of compr. unit Mox temp. 35"C i CopocHy 1 MW. -*4-i-v-^

OII-»y»tem. (and componant box**)

Va-oontalnm*nt Sotrty borrivr.

Cooling woUr.

Scm* comprsisor, Moderator chamber.

Hj-blower. 'Circuiting pump.

ton—g«tterpump. Separator (trap).

Heat sxdionger.

PA) M«atur* point, P»pr»«surt A-*alorm ^-f T-T»mp«rrtur« Wndlcotor. R-Rodlotlon Ocontro). S-nrRch-c«r

P<] Vahn. manual. voiv». Sprlngloadwl chock volve. LJ Bunting dltk. Ramot* controllad votv«. Safety valve. •"-•» Bunrtlng dltk. Praetuni reducing vatve. Temp, mox- 35 *C. 40 kw. Max. 3S°C. 2kw.

T T I I Water cooling of in pBe parts. U0X.J5-C, 40kw.

I LJ31. Rgure no.10 Diagram for Cold Neutron Source Backfilling situation.

ess3a3 Cooling of compr, unit Max temp. 3S*C Capoclty 1 MW.

0II-«yirtem. (and component boxm) He—«y*tem. _J 1 1 l_

— — Coding water.

Scrvw compfesaor. \J Moderator chamber.

I J.J H,-blower. \M/ Cireutotlno, pump,

lon-getterpump. Sf Seponator (trap).

Hoot exchanger. >• Adeorber.

P~pr*MUT« A-olorm T-Temperoture I-Indicator. R-RcdlaUon C-control, F« S-»nHch-over

Valve, manual. I Helium evetem 2 Check valve. Sprtngloaded check vah*. LJ Bunrtlng dTek. Remote controlled varve. Sofety vaive. ~~+m Bursting Preeeure reducing vatve. Cooling of Hj-blowen.

J 1 Water cooling of in pis parts. Max.35*C, 40kw.

Figure no. 11

Diagram for Cold Neutron Source. Bleeding situation. Administration.

Cevil Mechanical Electrical Purchasing. Quality Authority engineers. engineers engineers. assuring. handling. TTT TTT i IT

Ad hoc.

31 Technicians. Mechanics. Electricians. Designers. C —s CD D O

ESS

Moderator department organisation. Timeschedule moderatordept.

12 3 4 5

1. Preliminary Design. 2. Basic Design. 10 3. Concept Approval. 3 4. Prepare contracts. 4 5. Detained Design. 36 6. Call for tender. 4 7. Purchase of standard equipment. 6 8. Manufacture of non standard equip. 10 9. Delivety and acceptance. 4 10.Test assembly. 15 11 .Final assembly outside target hall. 10 12.Assembly in target hall. 6 13.Final tests at target. 6 Figur e no.:1 3 Manyears 114 Administration 10 ad hoc 10 Total 134

ESS0RG2 •2^ '4\

Filter Pd—1 I—PS3-

Connections to inpile ports Cooling ond moderators Buffer

Ion — exchonlge filter

Heat exchanger

31 Compressor unit c CD

13 O Bibliographic Data Sheet Ris0-R-9O8(EN) Title and authour

Description of the Moderator Systems for the ESS Project

Karsten Stendal

ISBN ISSN

87-550-2198-0 0106-2840

Department Date

Engineering and Computer Department October 1996

Pages Tables lllustartions References

43 14

Abstract (max. 2000 characters)

This paper describes a suggestion for the arrangement of the Cold Neutron Sources for the two targets in the ESS project.(European Spallation Source). The suggestion is based upon the technique of the existing cold neutron sources at Ris0 in Denmark, HMI and Geestacht in Germany. As moderating media all of them use H2 in supercritical condition, circulated by blowers, and the safety of the systems is based upon the triple-containment philosophy. This seems to be the most convenient principle to use near the ESS targets, as it provides a larger degree of freedom with respect to the arrangement of these sources and pipe connections to the chambers, especially because the space is limited and access to the target is relatively complicated. The moderator chambers have been designed by KFA, Jiilich and the rest of the arrangement by Ris0, DK. The price calculations used for the ESS project are based upon this arrangement.

Descriptors INIS/EDB

COLD NEUTRONS; COST ESTIMATE; DESIGN; FABRICATION; HY- DROGEN; MODERATORS; NEUTRON SOURCES; SPALLATION; SPECI- FICATIONS; TARGETS

Available on request from Information Service Department, Ris0 National Laboratory, (Afdelingen for Informationsservice, Ris0 National Laboratory), P.O. Box 49, DK-4000 Roskilde, Denmark. Telephone +45 46 77 46 77, ext. 4004/4005, Telex 43 116, Telefax +45 46 75 56 27 Objective Ris0's objective is to provide society and industry with new opportunities for development in three main areas: • Energy technology and energy planning • Environmental aspects of energy, industrial and agricultural production • Materials and measuring techniques for industry

In addition, Ris0 advises the authorities on nuclear issues.

Research profile Ris0's research is strategic, which means that it is long-term and directed toward areas which technological solutions are called for, whether in Denmark or globally. The reasearch takes place within 11 programme areas: • Wind energy • Energy materials and energy technohgies for the future • Energy planning ' Environmental impact of atmospheric processes • Processes and cycling of matter in ecosystems • Industrial safety • Environmental aspects of agricultural production • Nuclear safety and radiation protection • Structural materials • Materials with special physical and chemical properties • Optical measurement techniques and information processing

Transfer of Knowledge Ris0's research results are transferred to industry and authorities through:

• Co-operation on research ' Co-operation in R&D consortia • R&D clubs and excfiange of researchers • Centre for Advanced Technology • Patenting and licencing activities

And to the world of science through:

• Publication activities Ris0-R-9O8(EN) • Network co-operation ISBN 87-550-2198-0 • PhD education and post docs ISSN 0106-2840

Available on request from: Information Service Department Key Figures Ris0 National Laboratory Ris0 has a staff of more than 900, including more than 300 EO. Box 49, DK-4000 Roskilde, Denmark researchers and 100 PhD students and post docs. Ris0's Phone +45 46 77 46 77, ext. 4004/4005 1996 budget totals DKK 471 m, of which 45 % come from Telex 43116, Fax +45 46 75 56 27 http://wwvv.risoe.dk research programmes and commercial contracts, while the e-mail: [email protected] remainder is covered by government appropriations.