An Overview of Cryogenic Operations at ESS J. G. Weisend II, P. Arnold, E. Bargallo, C. Darve, N....

An Overview of Cryogenic Operations at ESS

J. G. Weisend II, P. Arnold, E. Bargallo, C. Darve, N. Ellias,J Fydrych, W. Hees, J. Jurns, D. Piso, X.L. Wang

October 2014

Accelerator Ops 2014 - J.G. Weisend II 2

Outline

• Introduction to ESS• Cryogenics at ESS• Operating Scenarios• Controls• Staffing• Reliability Strategy• Summary

October 2014


Introduction to ESS

The goal of ESS is to provide a spallation based neutron source significantly more powerful than existing sources: 30 - 100 times brighter than ILL and 5 times more powerful than SNS

This facility will enable neutron based research in a wide range of fields including: materials science, condensed matter and biomedical studies

October 2014


ESS Overview

October 2014

5 Times more powerful than SNS30 -100 times brighter than ILL


Applications of Cryogenics at ESS

October 2014

• Cooling for the cryomodules (2 K, 4.5 – 300 K and 40 K)• Cooling for the Target supercritical H2 Moderator (16.5 K)

• Liquid Helium and Liquid Nitrogen for the Neutron Instruments

• Cooling for the cryomodule test stand (2 K, 4.5 – 300 K and 40 K)

• This is accomplished via 3 separate cryoplants


ESS Cryogenic System

October 2014


Accelerator Cryogenics

• Bulk of acceleration is carried out via 3 classes of SRF cavities: Spoke, Medium (b = 0.67 ) Beta Elliptical and High (b = 0.86) Beta Elliptical

• No superconducting magnets in the accelerator. There are some in the instruments

• Cavities operate at 2 K with a 40 – 50 K thermal shield

• Power coupler cooling from 4.2 K to 300 K

• Accelerator lattice permits an 14 additional cryomodules to compensate for lower than expected cryomodule gradients (Stage 2)

October 2014


ESS Accelerator Cryoplant (ACCP)

• Provides cryogenic cooling to Cryomodules• 13 Spoke and 30 Elliptical (Stage 1)• Sized to allow an additional 14 Elliptical Cryomodules for

design contingency (Stage 2)

• Allows for number of operating modes• Connected to the cryomodules via a cryogenic

distribution system• High availability and turn down capability are

important features• Compressor heat is absorbed by Lund District Heating

System (unique ESS feature)October 2014


ACCP Capacities

October 2014


Cryogenic Distribution System

October 2014

• Allows warm up and cool down of one or more cryomodules w/o affecting remaining cryomodules

• Connection between distribution line & cryomodule is done via fixed connections

• Separate isolation vacuums in the distribution lines and cryomodules

• Operating modes defined

• Conceptual design complete

• Detailed design and production via IKC or commercial contract will start by Q1 2015

• Cryogenic Distribution System must be complete and installed by December of 2017


Cryogenic Distribution Line (310 m) comprising 43 valve boxes

Endbox

Cryogenic Transfer

Line (75 m)

Splitting box

Linac CDS – function and layouts

21 High Beta Cryomodules

(174 m)

9 Medium Beta Cryomodules

(75 m)

13 Spoke Cryomodules

(54 m)

LinacCryoplant

Superconducting section of the Optimus Linac (303 m)

Auxiliary process lines

Cryogenic System of the Optimus Linac

October 2014


Elliptical Cryomodules in ESS Tunnel

October 2014


Target Moderator Cryoplant

• Cools the Supercritical H2 neutron moderators that surround the target

• Provides 20 kW of cooling at 16.5 K via GHe to the He/supercritical H2 heat exchanger

• Moderator design is still under development and final heat load won’t be known until late 2014

• ESS Target Division responsible for the supercritical H2 system

• Compressor heat is absorbed by Lund District Heating System (unique ESS feature)

• Cryoplant should be ordered in 2016 and fully commissioned by December of 2018

October 2014


Test and Instruments Cryoplant

• Provides cooling at 2 K, 40 K and 4.5 K liquefaction for elliptical cryomodule testing

• 2 K operation done via warm vacuum pumps

• During ESS operations, provides up to 7500 l per month of LHe to the instruments

• Helium is recovered, purified and reliquefied

• Sufficient LHe storage planned to allow several weeks of Science Ops in the case of cryoplant failure

October 2014


Test and Instruments CryoplantCapacity and Status

• The plant will produce:

• 75 W @ 2 K, • 422 W @ 40 K• 0.4 g/s at 4.5 K for coupler cooling

• A plant this size exceeds the 7500 l / month liquefaction requirement

• Cryoplant should be ordered in August 2015 and fully commissioned by July 2017

October 2014


Helium Recovery and Storage

• The ESS goal is to recover, purify and reuse as much He as possible

• ACCP and TICP cryoplants will share a common gas system while TMCP has separate storage that can be cross connected

• The system will include a separate cryogenic purifier

• Systems will be provided by IKC or separate contracts

• Expected He Storage Capacities:

• LHe• 20 m3 (Includes storage for second fill of linac)• 5 m3 (Backup for Instruments He)

• GHe (20 Bar) • 1000 m3 - sufficient to hold all the linac inventory

• GHe (200 Bar)• 12 m3 - Instrument He storage

October 2014


Operation Planning

• Cryogenic plants will be commissioned separately, but will eventually be operated simultaneously.

• When operating, cryogenic plants will run 24/7

• Once cryomodule testing is complete (~ 2021) TICP will only be periodically operated to create LHe for instruments

• Modern automated cryogenic plants have been shown to operate continuously and reliably without the constant presence of an operator

• Staffing is planed to allow 24/7 presence of Cryogenic Operators/Technicians on site. However, after sufficient commissioning and preliminary operations time ( ~ 2 years) , it is expected that cryoplant operators will only be called in outside normal business hours in case of problems.

• Once cryoplant commissioning is complete, Accelerator Operators in the ESS Control room will monitor the cryogenic system & make routine adjustments with Cryogenic Operators addressing problems & making operating mode changes (warm up, cool down etc.)

October 2014


Operation Planning

• Instruments will need access to LN2 and LHe 24/7

• LHe deliveries will be done by the STS Group. This will normally be done on day shift but on call staff will be available for exceptional cases.

• Our goal is to recover all the helium. Automated He recovery system does not require constant staff presence.

• LN2 supplied to large dewars on site by commercial vendor and distributed to users via local LN2 distribution systems or smaller dewars. GN2 is vented to atmosphere.

October 2014


Operation Planning

• ESS plans two long shut downs per year (6 weeks in winter & 10 weeks in summer)

• Cryoplants during these periods will be shut down or possibly operating at 40 K standby (ACCP)

• These shut downs are sufficient for routine large scale maintenance on the cryogenic systems

• During unscheduled repair periods, cryoplants will remain at their nominal operating conditions unless a cryogenic component needs repair

• Unnecessary thermal cycling will be avoided (individual cryomodules can be thermal cycled for in situ repair)

• Replacement or addition of entire cryomodules is best done during long shut downs when the cryogenic system is warm

• The majority of preventive maintenance for the Cryogenic System concerns the 300 K portion and much of this can be done without interrupting cryogenic operations

October 2014


Tentative ESS Operating Schedule duringSteady State Operations (2026 & Beyond)

October 2014

Accelerator Ops 2014 - J.G. Weisend II 21October 2014

Linac & Cryomodule Operating Modes


Cryogenic Modes for Linac and Cryomodules

October 2014


General Controls Strategy

The ACCP control strategy shall be based in EPICS to provide monitoring and operational capabilities for the ACCP.

Functions for supervisory controls and batch operations shall be running in the EPICS process controller (EPICS IOC) for a fully automated operation of the ACCP.

PLCs shall be used for all functions with substantial technical safety requirements and deterministic logic for controlling the process. Each PLC shall have an interface to the EPICS process controller (IOC).

The logic shall be split between EPICS IOC and PLCs in such a way that boot, restart or breakdowns of EPICS IOC, HMIs, etc. do not affect the control of the cryogenic process .

Cryoplant vendors For ACCP and TMCP produce all control programming including EPICS programming & HMIs for commissioning

ICS will provide PLC standards, EPICS backbones, utilities and integration support

ICS may also provide controls programming for TICP plant & ancillary cryogenic systems (recovery, gas management etc.)

Some controls programming may be done by in kind contributorsOctober 2014


General Controls Strategy

October 2014


Planned Staffing

During Construction & Installation:

7 – Engineers ( Cryogenic, Mechanical, Controls)

3 – Operators / Technicians

Support from other Work Packages (Electrical, Water Cooling, Vacuum etc.)

During Commissioning and Operations

6 – Engineers

8 - Operators/Technicians

Support from other operating groups (accelerator, Conventional Facilities etc.)

October 2014


Staff Development

• Almost all engineers required for construction phase have been hired with remainder to arrive in 2015

• Current engineering staff will transition to operations duties and support in 2018 – 2019

• Operators will perform maintenance & support roles (e.g. LHe distribution) They may be available to support vacuum techs or other accelerator operations

• Operators and technicians will start to be hired in 2016 to allow training and participation in installation & commissioning

• Operators & technicians are expected to be hired locally• Training of new staff will include classroom (LU activities), on the job

and possible secondment to similar existing facilities• We are investigating the development of simulation software for the

ACCP to assist in training

October 2014

27

RAMI analysis of the cryoplant

Purposes of the analysis

Reliability and availability considerations in the tendering phaseContribution of the cryoplant to the overall availability and reliability of ESS

Methodology followed

Components reliability and maintainability provided by companiesFailure mode analysis (components with their functions, possible failures and the consequences)Availability and reliability modelingResults to see differences between the different proposalsIterative process with more detail in the design, more accurate assumptions and models to:

Analyze the design and propose changes and recommendations if it does not fulfill the requirementsForesee preventive and corrective maintenance actions, spares and tools


Summary

• Cryogenics will play a major role in ESS and affects the accelerator, target and instruments projects

• Work is well underway• A very skilled team has been assembled• Sizable procurements will start in 2015• An Integrated Controls strategy has been developed• Detailed reliability studies are underway• Civil construction has started

• Once full operations start ( ~ 2023) routine operation of cryoplants will be covered by accelerator operators• Current plan allows 24/7 coverage by cryogenics operators

• Challenges include:• Staff development• Meeting reliability goals• Helium conservation

October 2014

An Overview of Cryogenic Operations at ESS J. G. Weisend II, P. Arnold, E. Bargallo, C. Darve, N....

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