Ricardo-AEA. In-Situ Filter Testing & Stack Sampler Characterization. John Osbourn. Particle Measurement Centre.

Transcription

1 Ricardo-AEA In-Situ Filter Testing & Stack Sampler Characterization John Osbourn Particle Measurement Centre

2 Outline In-Situ Filter Testing Stack Sampler Characterization Filtration mechanism performance Sampling location Isokinetic sampling Test aerosol Generation Measurement Sample transport Regular testing Representative measurements Maintenance & reliability Standards & guidance 2

3 Example Ventilation System 3

4 Filtration High Efficiency Particulate Air (HEPA) Filtration increases exponentially with filter media thickness Passive devices (no external services) Filter construction: Paper of glass fibres of different diameters and lengths plus binder to increase paper strength Maximum Penetration Particle Size (MPPS) to 0.3 µm Increase thickness - higher efficiency Pressure drop proportional to paper thickness face velocity 4

5 In-Situ Filter Testing & Stack Sampler Characterization Filtration Mechanisms 5

6 Typical Collection Efficiency 6

7 Thermo-pneumatic Smoke Generator 7

8 Aerosol Photometer 8

9 Example Single Stage System 9

10 Representative Sampling 10

11 Single & Multiple Point Sampling 11

12 Stack Sampling System 12

13 Stack sampler example 13

14 Sampling location 14

15 Choice of sampling location Velocity Profile the velocity and air flow distribution must be known, so that the sampler can be correctly set to isokinetic conditions < ± 20 % variation e.g. BS848-3:2001, BS EN ISO 5802:

16 Choice of sampling location Number of extraction points required multiple extraction points from the duct or stack required, for a duct area in the range to 2.32 m 2 the suggested number of extraction points is from 4 to 12 fewer withdrawal points may be used if careful studies in given instances have shown that uniformity of composition exists throughout the cross section of the duct Concentration profiling (BS ISO 9096:2003) Inject Tracer Dispersed oil particulate After filters Cover all possible sources Measure Concentration Profile < ± 20 % variation 16

17 Choice of sampling location 17

18 Choice of sampling location 18

19 Choice of sampling location Either Sample from a position where there is complete mixing of any effluent with the discharge air Single point sampling Simple Inexpensive Analysis Capital cost Easy to maintain Reasonably accurate (provided properly placed) Or Sample from a position where mixing is incomplete Multi-point sampling Discrete Very accurate Expensive Analysis Capital cost Combined (manifolded) Difficult to design Subject to particle losses Flow balance (anisokinetic) Small nozzles 19

20 Manifold multi-point samplers 20

21 Isokinetic Sampling 21

22 Particle transport 22

23 Standards & guidance NVF/DG001 An Aid to the Design of Ventilation of Radioactive Areas, Nuclear Industry Guidance Document replaces UKAEA AECP 1054 UKAEA - AECP 1072 Sampling and monitoring of airborne radioactive discharges - Issue historical document Environment Agency - TGN M11 Monitoring of Radioactive Releases to Atmosphere from Nuclear Facilities being revised BS ISO 2889: 2010 Sampling airborne radioactive materials from the stacks and ducts of nuclear facilities current 23

24 Sampling system testing whole system Inspection Physical condition (including sampling nozzle) Leak testing Profiling Velocity Sub-micron aerosol concentration < ± 20 % variation Sub-micron aerosol sampling efficiency > 80 % Coarse aerosol sampling efficiency (minimum) Measured qualitative assessment Calculated (> 50 % at 10 µm) AECP 1072 recommended on commissioning and every 5 years thereafter 24

25 Sample system testing - routine Inspection Physical condition (not including sampling nozzle) Leak testing Velocity profile < ± 20 % variation Isokinetic sampling rate AECP 1072 recommended annually 25

26 Maintenance & reliability High reliability required Outage time of < 9 hours per year for continuous sampling System alarms Routine maintenance schedule Essential component back-up Stand-by on system Designated spares 26

27 John Osbourn Ricardo-AEA Ltd Unit 2 Ludbridge Mill Reading Road East Hendred Wantage Oxon. OX12 8LN T: E: W: / john.osbourn@ricardo-aea.com / PMC@ricardo-aea.com