gas system for gif in ehn1 - cern

EDMS NO. REV. VALIDITY

1405544 0.0 RELEASED

REFERENCE

EHN1-GIF

Date : 2013-03-14

CERN CH1211 Geneva 23 Switzerland

SAFETY FILE (part)

Gas System

for

GIF in EHN1

DOCUMENT PREPARED BY: DOCUMENT CHECKED BY: DOCUMENT APPROVED BY:

A. Fabich R. Guida

SBA PH

HSE

EN DSO PH DSO

REFERENCE EDMS NO. REV. VALIDITY

EHN1-GIF 1405544 0.0 RELEASED

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HISTORY OF CHANGES REV. NO. DATE PAGES DESCRIPTIONS OF THE CHANGES

0.0 140604 All First version



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TABLE OF CONTENTS

1. SCOPEOFTHEDOCUMENT.................................................................................................................................5

2. BRIEFINTRODUCTIONTOGIF...........................................................................................................................5

3. OVERVIEWOFTHEGASSYSTEM......................................................................................................................6

4. SYSTEMPARTS........................................................................................................................................................6

4.1 GASES.........................................................................................................................................................................64.2 GASPIPINGANDPANELS..........................................................................................................................................74.3 NOMENCLATUREFORGASPIPES,PANELSANDWELDS...........................................................................................84.4 GASROUTING.............................................................................................................................................................8

5. MONITORING.........................................................................................................................................................10

6. SAFETYMONITORING.........................................................................................................................................10

7. DISMANTLING.......................................................................................................................................................13



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TABLE OF FIGURES

Figure 1: A general view of the GIF facility on the Saleve side (3D from Catia). ............................................ 5Figure 2: Gas distribution lines in the bunker shortly after completion of the welding work, before installation of the cable trays and the raised floor. In the centre one can see the destination of pipe patches at the arrival of the place, where two patch panels will be installed. In the lower picture the additional piping from other panels on the bunker arrive from the left. All lines together run to the right, where they traverse the shielding leading to the service zone. ................................................................................................................... 10Figure 3: Flammable gas detection in the service area .............................................................................. 11Figure 4: Flammable gas detection in the preparation area ....................................................................... 12Figure 5: Flammable gas detection in the bunker ..................................................................................... 12



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1. SCOPE OF THE DOCUMENT The document describes the gas system dedicated to the Gamma Irradiation Facility (GIF).

2. BRIEF INTRODUCTION TO GIF The installation of the Gamma Irradiation Facility (GIF, formerly called GIF++ differing from the old GIF installation in the West Area) is placed in EHN1 of the SPS North Area. A general view of the foot print is available in SPSXFGIF0101 (EDMS 1380120), where location on the H4 beam line is shown in (SPSXLHN10003, EDMS 768898).

The main part of the facility (Figure 1) is the irradiation area hosting the irradiator with a 137Caesium source with a nominal activity of 14 TBq. This irradiation area is denominated as Bunker. Adjacent are two main areas: a) the Preparation Area and b) the Service Area, which hosts electronic racks on the first floor and the Gas (Mixing) zone on the first floor.

The bunker with the adjacent areas is surrounded by other beam areas and corridors, typical for EHN1.

Figure 1: A general view of the GIF facility on the Saleve side (3D from Catia).

The GIF areas in EHN1 are considered as open space, except for the bunker, which is covered with a concrete roof. There is no ventilation system and the bunker volume (~400 m3) is exposed to natural convection only, mainly via the two personnel access doors (PPE and PPX). These areas are all equipped with a raised floor (40 cm), where natural convection is possible through trench openings along the shielding walls.

A common concept for the active alarm systems (AUG, AUL, fire detection, ODH, gas detection …) of the general infrastructure in the Experimental Areas is currently in discussion (EDMS 1365914). In its final version it will also be applied to GIF. It is envisaged



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equipping GIF with fire detection (bunker only), ODH and flammable gas detection and AUL (cutting the electricity of GIF and assigned control room). AUGs will be placed in the adjacent corridors.

3. OVERVIEW OF THE GAS SYSTEM With the GIF purpose for testing mainly gaseous detectors, the design provides a very flexible supply system with the capability of delivering numerous gases (and mixtures) at the same time. The gas system composes mainly of four parts:

- Gas hut (build 909) and standard supply lines to EHN1 patch panels located along the wall on the Jura side

- Dedicated supply from the EHN1 panels to the supply panels in the GIF service area

- The gas zone in the GIF service area, equipped with racks for gas mixing and surveillance

- The distribution system from the GIF service area to the areas for detector tests and the ventilation lines

Additionally to these permanent installations one also adds the flexible installations of the users’ equipment to be tested.

This document covers primarily the permanent installations. The layout of the users’ equipment cannot be anticipated in detail, but is assumed to be a typical gaseous detector of LHC type experiments with sizes up to e.g. an ATLAS MDT single module. Up to a dozen of detector elements can be placed simultaneously in the bunker and in the preparation area. The operational aspects are based on general assumptions for such systems and the safety systems are designed accordingly.

In the further text, unless specified explicitly the notation “gas” also refers to “gas mixtures”, either directly provided from the gas hut or mixed in the service zone.

4. SYSTEM PARTS

4.1 GASES In order to keep the flexibility for testing purposes of all kinds of gaseous detectors, the gas types are not limited, except that pure hydrogen is excluded. They can be neutral, flammable, of type “green-house” and the density at STP can vary from lighter to heavier than air. The following list should give an overview of typically used gases, but it is non-exhaustive:

Ar, CO2, N2, He, CF4, Xe, Ne, O2 considered as neutral gases

iC4H10, CH4, Ar/H2, C2H2F4, Freon (SF6, C4F10, C3F8) considered as flammable gases

These gases will be provided from the gas hut. Purity levels can vary depending on the users’ requests.



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The maximum applied pressure in the supply lines is 3 bar, in the distribution lines to the bunker/preparation area a few 10-3 bar above atmospheric pressure. The flow rate of the distribution to the bunker/preparation area is up to 5 l/min per line.

4.2 GAS PIPING AND PANELS The newly installed piping diameters are OD/ID 8/6 mm and 10/8 mm for the distribution lines from the gas zone to the bunker/preparation area, 12/10 mm for newly installed supply lines and 22/18 mm for the ventilation lines. The installed pipe work sums to a total length of about 5.5 km.

The activation of materials in GIF will be negligible (mainly photons, typical low-intensity charged particle beams of EHN1). The prompt radiation from the irradiator source can reach levels of 1 Sv/h in the bunker, which has impact on the design choice using carbon based polymers. The permanent installation of the gas system in the bunker does not include any thermoplastics (carbon based polymers), which might be subject to degradation due to prompt radiation.

4.2.1 PIPE MATERIAL The newly installed piping is purely of stainless steel (316L, 1.4435). The material certificates can be found in EDMS 1369505. The cleaning and delivery specifications are described in EDMS 1358277. The pipe installation is qualified for use as PN10 (N.B.: this does not include the gas (mixing) equipment in the gas zone racks provided by PH and the users’ equipment).

4.2.2 PIPE INSTALLATION The plying and welding work was executed by the CERN EN/MME team (supervision S. Atieh, D. Lombard) with qualified welders (reference documents?). Orbital welding (ARC machines) was applied for all connections pipe-to-pipe (except for the ventilation lines - tbc). Primarily intended for lines dedicated to flammable gases, the orbital welding was chosen for all lines, including the ones dedicated for neutral gases. This suppressed the used of different connecting methods, e.g. tube fittings. A protocol of the welding work (date, welder, welding joint …) will be provided upon completion of the work. About 1100 welds were completed.

The welding work and the related quality control was subject to EN-13480 with piping Class I. The piping Class I was deliberately chosen to guarantee a complete quality control (see below), although with the used piping material and allowed gas pressure Class 0 would qualify with the applied norm.

The quality control of the welding work included three steps: visual inspection (100% of the welds), radiography (more than 10% of all welds with focus on the piping dedicated for flammable gases), leak and (24-hour) pressure test of all lines. The corresponding protocols will be provided upon completion.



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4.2.3 GAS PANELS Panels of the type SCEM 59.70.60.010.2 for neutral and SCEM 59.70.60.020.0 for flammable gas lines will be installed for the supply to the service zone.

The panels in the distribution lines are in-house constructions (PH) and provide bulk head connectivity, some equipped with T-valves allowing to switch between the destinations of bunker and preparation area. A preliminary design is available in EDMS 1372322. Each distribution panel is equipped to provide 6 independent, closed gas loops.

4.3 NOMENCLATURE FOR GAS PIPES, PANELS AND WELDS All newly installed gas pipes, panels and welds have unique identifiers for documentation of quality control, maintenance and operation.

The panels (supply and distribution) are numbered according to the purpose and the position, and are of the form Lnn, e.g. S01, G02 …

Sxy is a gas Supply panel in the service zone, Gxy is a Gas distribution panel

x is the index indicating the area position: 0=service zone, 1=preparation area, 2=bunker

y is a running index for the panels within the area.

For a second panel connected in parallel with another panel in the same zone an additional “B” is added to the identifier (applies only to the service zone).

The nomenclature of the piping is LnnDyy and the welds follow the scheme LnnDyy-n:

The part before the dash identifies a unique gas line:

o Lnn: The destination panel (either supply panel in the gas zone or distribution panel at destination of bunker/preparation zone), e.g. S01, G23

N.B.: The supply panels SxxB do not have independent welds. They are connected in parallel to the corresponding panels without appendix B. The ventilation lines are indicated by V01 and V02.

o D: =A or =R, differing between the flow direction (A=aller, R=retour). In case of the supply and the ventilation lines the part Dxx is omitted working only one-way.

o yy is a running index from 1 to 6 indicating the closed loops of each panel

o n is a running index along the line indicating the weld

4.4 GAS ROUTING

4.4.1 THE GAS ROUTING FROM THE GAS HUT TO EHN1 The gases to GIF are initially supplied from the gas hut (building 909) via the patch panels located along the EHN1 wall (inside) on the Jura side. This installation is existent and is operated since ages.



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The gas hut hosts bottles, bottle batteries or vessels of various gases, which are partly heated depending on the gas type. A single gas volume, connected to a supply line, is limited to 120 m3 (STP).

As this installation and operation is common to all facilities in the whole of EHN1, the system shall be described in the EHN1 description in more detail.

The gas panels relevant to GIF are located at the positions 887/1‐B94, 887/1‐B79 and 887/R‐A81. A layout of these gas panels and the assignment of gas types are shown in the document EDMS 1361498. The assignment of gas types to the supply lines can be varied according to the needs of the users.

4.4.2 GAS SUPPLY ROUTING TO GIF SERVICE ZONE Starting from the EHN1 patch panels, newly installed piping (OD/ID 12/10 mm) allows the delivery of supply gases to the service area – gas zone.

In total 15 lines run from the EHN1 wall on the Jura side, via the underground gallery GHN105, to the service area and to the first floor, where the GIF supply panels are installed. A positioning of the supply panels including a numbering is shown in SPSXFGIF0034 (EDMS 1332833), where the initial gas type assignment is listed in EDMS 1361498.

The service zone hosts 5 supply panels, where 2+2 are for neutral gases (S00, S00B, S01, S01B), the remaining one for flammable gases (G02). Another supply panel is placed in the preparation area (S10) connected in parallel with S00/S00B (see drawing SPSXFGIF0034 EDMS 1332833 for positioning and pipe routing).

4.4.3 GAS DISTRIBUTION WITHIN GIF Standard SPS racks (green, 60 cm x 80 cm) are provided in the gas zone, which allows the installation of PH equipment for mixing and monitoring purposes (PH has to provide more input here). From the GIF supply panels the gas equipment is supplied, which in turn is connected to the distribution panels (see drawing SPSXFGIF0034 EDMS 1332833 for positioning and pipe routing).

A total of 8 distribution panels in the service zone, each equipped with 6 in- and 6 out-going connections. All lines of the 8 panels are connected to the 8 patch panels in the bunker, only 4 out of these are connected with patch panels in the preparation area. Of the eight panels (with their lines) two are dedicated flammable gases. The other six panels are for neutral gases. Neutral lines supplied with non-flammable gas containing flammable gas concentrations below LE are continuously monitored and have automatic cut-off. A summary of the relation between panels in the service zone and the bunker/preparation area is listed in EDMS 1361498. Figure 2 shows an impression of the piping inside the bunker shortly after completion of the welding work.

4.4.4 VENTILATION LINES Two ventilation lines are installed leading from the bunker to the outside of EHN1. Direct connection allows venting gases, which are not in a closed loop. One line is intended for



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neutral gases, the other one for flammable gases, which has a forced flow driven by injection of a neutral gas.

Figure 2: Gas distribution lines in the bunker shortly after completion of the welding work,

before installation of the cable trays and the raised floor. In the centre one can see the destination of pipe patches at the arrival of the place, where two patch panels will be installed. In the lower picture the additional piping from other panels on the bunker arrive from the left.

All lines together run to the right, where they traverse the shielding leading to the service zone.

5. MONITORING GIF will mostly run without the permanent presence of personnel in adjacent areas or in the control room. Monitoring will be implemented for various aspects, also in the interest of the users to maximize the up-time. Dedicated safety systems for the detection of fire, ODH and gases will be installed independently of users’ monitoring.

6. SAFETY MONITORING The installation of active alarm systems (AUG, AUL, fire detection, ODH, gas detection …) of the general infrastructure will follow the guidelines from the discussion based on EDMS 1365914. EN/EL, EN/MEF and HSE are currently working on a common agreement. This follows the safety recommendations provided by HSE (EDMS 1339774).

Focussing on the gas safety this will be covered by detection systems for ODH and flammable gases with the following baseline:

ODH in closed areas: bunker and underground gallery shall be monitored on a global level. The bunker shall be equipped with ODH sensors (2) in the raised floor, which is connected for natural air flow to the bunker volume, detecting heavy gases. Light



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gases will rise to the ceiling, where the tile roof allows the escaping of these gases through construction-conditioned gaps to the “outside” volume within EHN1.

Flammable gases: in all places, where there are connections with tube fittings on lines used with flammable gases. Identified places are the patch panels and the racks in the service zone, which are dedicated to flammable gases. Additionally there will be the provision of detector cables for connecting mobile detector heads. Figures 3-5 show the proposed positioning for flammable detection heads in the service zone, the preparation area and the bunker (excerpt from the document EDMS 1380092).

Figure 3: Flammable gas detection in the service area



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Figure 4: Flammable gas detection in the preparation area

Figure 5: Flammable gas detection in the bunker



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7. DISMANTLING With no material activation and no resident chemical or poisonous pollution the dismantling and potential material recuperation is without specific safety hazards.

gas system for gif in ehn1 - cern

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