Interesting findings of a comparison of Real Time [Autosaved]
-
Upload
masood-inayat-rrpt -
Category
Documents
-
view
107 -
download
0
Transcript of Interesting findings of a comparison of Real Time [Autosaved]
Interesting findings of a comparison of Real Time versus Passive Radon Thoron Monitoring
In a Rare Earth MineMasood A InayatRSO, Molycorp Inc.July 14, 2015
Radon Thoron Monitoring
Objectives Impact of Passive monitoring in accurately
determining exposures Impact of single anomalous event on passive
monitoring Weighted averaging in real time versus linear
averaging in passive monitoring Radon Thoron ratio accuracy in real time monitoring
versus passive monitoring Timely results with ability to mitigate in real time
monitoring versus passive monitoring
Traditional approach passive monitoring Track Etch Detectors
Radon only
Type DNRM (Radon Only) Filter makes the short lived thoron (55
second half life) to decay before entering the detector
Radon plus thoron
Type DNRF (Radon + Thoron) No filter allows both radon & thoron to
enter the detector
Operation principle
Inside both Type DNRM & DNRF detectors is a piece of film that records the impacts (tracks) of alpha particles produced by the decay of radon/thoron and their decay by-products. These detectors are also knows as Alpha track or track etch detectors.
Continuous real time monitoring Alphaguard Continuous Real Time Radon Thoron monitor
Comparison Alpha Track (Passive) Alphaguard (Active)Low Per Unit Cost Yes NoAccuracy Somewhat YesReliability Somewhat YesTimeliness No Yes
Comparison
DNRF OR DNRM $15-$20 each X # of units deployed location X Monitoring Time frames (monthly quarterly etc.)2013 54 units monthly exchange 54 X 12 X15= $9720Currently 14 units quarterly exchange 14 X 4 X 20 = $1120
Alphaguard $12000-15000 per unit
Passive Vs. Real Time
A rare earth mine expansion perspective
Existing facilities for passive monitoring quarterly exchangeLegacy facilities monitored on quarterly exchange basis
CHP Fenceline Fenceline #1Fenceline #2 Fenceline #3
Didymium Packaging Lanthanum Packaging
2013 Existing Facilities Rn+Tn data comparison of real time versus passive monitoring shows consistent high results for real time monitoring as compared to passive monitoring
CHP Area Didy Room Fenceline #1 Fenceline #2 Fenceline #3 Lanthanum Packaging
0
1
2
3
4
5
6
7
8
2013 Real Time Vs Passive Exist-ing Facilities Comparison
Real Time Rn+Tn Passive Rn+Tn
CHP Area Didy Room Fenceline #1 Fenceline #2 Fenceline #3 Lanthanum Packaging
0
1
2
3
4
5
6
7
8
2013 Real Time Vs Passive Exist-ing Facilities Comparison
Real Time Rn+Tn Passive Rn+Tn
2013 Radon Only real time versus passive data shows relatively similar average radon concentrations although the difference is observed in different areas
CHP Area Didy Room Fenceline #1 Fenceline #2 Fenceline #3 Lanthanum Packaging
0
0.1
0.2
0.3
0.4
0.5
0.6
2013 Real Time Vs Passive Exist-ing Facilities Comparison
Real Time Rn Passive Rn
CHP Area Didy Room Fenceline #1
Fenceline #2
Fenceline #3
Lanthanum Packaging
0
0.1
0.2
0.3
0.4
0.5
0.6
2013 Real Time Vs Passive Ex-isting Facilities Comparison
Real Time Rn Passive Rn
2013 Thoron only real time versus passive data showing higher thoron concentrations for real time than passive monitoring.
CHP Area Didy Room Fenceline #1 Fenceline #2 Fenceline #3 Lanthanum Packaging
0
1
2
3
4
5
6
7
8
Real Time Tn Passive Tn
CHP Area Didy Room Fenceline #1 Fenceline #2 Fenceline #3 Lanthanum Packaging
0
1
2
3
4
5
6
7
8
Real Time Tn Passive Tn
New facilities online in 2013
With addition of new facilities beginning in 2013 a monthly radon thoron passive monitoring regime was put in place for the above listed facilities
New facilities for passive monitoring monthly exchangeNew facilities monitored on monthly exchange basis
PASTE TAIL OUTDOOR
PASTE TAIL DEPOSITORY
CRACK 1A LEVEL 3
CRUSHER
PASTE TAIL INDOOR NW FENCE LINE CRACK 1A LEVEL 1
NEW MILL
NE FENCE LINE SXH&I CHP INSIDE P16 FENCE LINESX-D MINE PIT CHP CERIUM CHLOR ALKALI
2013 average Radon + Thoron results are showing higher results throughout the year during the new facilities construction
Ce Se
p
Chor
Alkali
CHP
Crack
Crushe
r
Mine Pi
t
NE Fenc
e
New Mill
NW Fence
P-16 F
ence
Paste SX
DSX
H&I0
0.51
1.52
2.53
3.54
2013 Passive Radon + Thoron (DNRF) Yearly Weighted Average Monthly Exchange
2013 Passive Radon + Thoron (DNRF) Yearly Weighted Average Monthly Exchange
Passive Radon Thoron (DNRF) Monitoring Lo-cationsRa
don
Thor
on C
onc.
pCi
/litr
e
CERIU
M SEP
CHLO
R ALK
ALI
CHP
CRACK
Crushe
r
MINE PIT
NE Fen
ce Lin
e
NEW MILL
NW Fence
Line
P16 F
ENCE LINE
PAST
ESX
-DSX
H&I0
0.51
1.52
2.53
3.5Average Rn+Tn
Monitoring Locations
Rn +
Tn
Conc
. pCi
/lite
r
Note the average passive radon levels are consistently1pCi/liter or higher throughout 2013 as the construction of the new facilities was progressing
CERIU
M SEP
CHLO
R ALK
ALI
CHP
CRAC
K
Crushe
r
MINE PIT
NE Fen
ce Lin
e
NEW MILL
NW Fence
Line
P16 F
ENCE LI
NEPA
STE
SX-D
SXH&I
00.5
11.5
22.5
33.5
Average Radon Only
Monitoring Locations
Rn C
onc.
pCi
/lite
r
CERIU
M SEP
CHLO
R ALKAL
ICH
P
CRAC
K
Crushe
r
MINE PIT
NE Fen
ce Lin
e
NEW MILL
NW Fence
Line
P16 F
ENCE LI
NEPA
STE
SX-D
SXH&I
00.5
11.5
22.5
33.5
2013 Passive Radon (DNRM) Yearly Weighted Average Monthly Exchange
Average Radon Only
Note with the exception of crusher and mine pit Thoron levels are either low or non existent throughout new construction areas during 2013. Thoron levels in these two locations are somewhat higher as Radon levels
CERIUM SE
P
CHLO
R ALKAL
ICH
P
CRACK
Crushe
r
MINE PIT
NE Fenc
e Line
NEW MILL
NW Fence
Line
P16 FE
NCE LINE
PAST
ESX
-DSX
H&I00.5
11.5
22.5
33.5
2013 Passive Thoron (DNRF-DNRM) Yearly Weighted Average
Monthly ExchangeAverage Thoron Only
CERIU
M SEP
CHLO
R ALKA
LI CHP
CRAC
K
Crushe
r
MINE PIT
NE Fen
ce Lin
e
NEW MILL
NW Fenc
e Line
P16 F
ENCE LI
NEPA
STE
SX-D
SXH&I
00.5
11.5
22.5
33.5
Average Thoron Only
Monitoring Locations
Tn C
onc.
pCi
/lite
r
ConclusionsWhile new facilities were being constructed monthly exchange monitoring was carried out in 2013 to study the impact. The results painted an unexpected picture as inferred below:1)Average Radon concentration values in areas where ore
processing and beneficiation activities were not taking place were showing higher than normal radon levels
2)Areas where ore processing and beneficiation activities were taking place were showing almost similar results
3)Radon numbers were showing higher but thoron numbers did not go up higher relatively
4)There was a need to find a common source impacting radon levels site wide irrespective of ore processing and beneficiation activities
5)Was it a leak in the old P-16 tailings dam due to heavy earth moving and construction equipment moving activity
6)Was it related to dust control process 7)Any other potential cause?
All 7 Fenceline PASSIVE RADON (DNRM) locations are reported as “LESS THAN INDICATED VALUE”
2014 Real Time Vs. Passive Radon Comparison
Fencel
ine #1
Fencel
ine #2
Fencel
ine #3
CHP F
encel
ine
NW Fencel
ine
NE Fen
celine
P-16 F
encel
ine0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
2014 Real Time Vs. Passive Radon Comparison
2014 Real Time Rn 2014 Passive Rn
Fencel
ine #1
Fencel
ine #2
Fencel
ine #3
CHP F
encel
ine
NW Fencel
ine
NE Fen
celine
P-16 F
encel
ine0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
2014 Real Time Vs. Passive Radon Comparison
2014 Real Time Rn 2014 Passive Rn
2014 Passive fenceline monitors show a consistent “LESS THAN DETECTED VALUE” of 0.33pCi/liter of Radon concentration at all locations versus a variable and higher radon concentration for real time monitoring.
All 7 Fenceline PASSIVE THORON (DNRF - DNRM) locations are reported
Locations 2014 Passive Rn 2014 Passive Tn 2014 Passive Rn+TnFenceline #1 0.33 0.13 0.45Fenceline #2 0.33 0.53 0.85Fenceline #3 0.33 0.60 0.93CHP Fenceline 0.33 1.03 1.35NW Fenceline 0.33 0.35 0.68NE Fenceline 0.33 0.23 0.55P-16 Fenceline 0.33 1.10 1.43
Alphaguard 2014 Fencelines Real Time Radon Thoron Monitoring AveragesLocations 2014 Real Time Rn
2014 Real Time Tn 2014 Real Time Rn+Tn
Fenceline #1 0.54 0.48 1.02Fenceline #2 0.27 6.78 7.05Fenceline #3 0.56 2.48 3.04CHP Fenceline 0.45 1.33 1.78NW Fenceline 0.45 2.6 3.05NE Fenceline 0.4 1.22 1.62P-16 Fenceline 0.67 2.85 3.52
2014 Real Time Vs. Passive Thoron Comparison
Fencel
ine #1
Fencel
ine #2
Fencel
ine #3
CHP F
encel
ine
NW Fencel
ine
NE Fen
celine
P-16 F
encel
ine0
1
2
3
4
5
6
7
8
2014 Real Time Vs. Passive Thoron Comparison
2014 Real Time Tn 2014 Passive Tn
Fencel
ine #1
Fencel
ine #2
Fencel
ine #3
CHP F
encel
ine
NW Fencel
ine
NE Fen
celine
P-16 Fe
nceline
0
1
2
3
4
5
6
7
8
2014 Real Time Vs. Passive Thoron Comparison
2014 Real Time Tn 2014 Passive Tn
2014 Passive fenceline monitors show a consistent lower Thoron concentration at all locations versus a higher thoron concentration for real time monitoring.
All 7 Fenceline PASSIVE RADON + THORON (DNRF) locations are reported
2014 Real Time Vs. Passive Radon+Thoron Comparison
Fencel
ine #1
Fencel
ine #2
Fencel
ine #3
CHP F
encel
ine
NW Fencel
ine
NE Fen
celine
P-16 Fe
ncelin
e0
1
2
3
4
5
6
7
8
2014 Real Time Vs. Passive Radon+Thoron Comparison
2014 Real Time Rn+Tn 2014 Passive Rn+Tn
Fencel
ine #1
Fencel
ine #2
Fencel
ine #3
CHP F
encel
ine
NW Fencel
ine
NE Fen
celine
P-16 Fe
nceline
0
1
2
3
4
5
6
7
8
2014 Real Time Vs. Radon+Thoron Comparison
2014 Real Time Rn+Tn 2014 Passive Rn+Tn
2014 Passive fenceline monitors show a consistent lower Radon+Thoron concentration at all locations versus a higher radon+thoron concentration for real time monitoring.
DiscussionOre @Mountain Pass contains an average of 0.005% Uranium and 0.02% Thorium content therefore:1. Thorium content is almost 4 times higher than Uranium content2. Uranium is the parent for Ra-226 the precursor for Rn-2223. Thorium is parent for Ra-228 the precursor for Rn-220 4. Therefore the Rn-220 average concentration should be about a factor
of 4 higher than Rn-2225. Passive monitoring does not support this ratio whereas real time
monitoring does6. Passive monitoring shows lower exposures with radon thoron
combined than with radon alone7. Passive monitoring may report higher than actual exposure for Radon8. Passive monitoring may report lower than actual exposure for Thoron9. Significance of Radon is important but significance of Thoron cannot
be ignored either10.In case of passive monitoring once a high exposure event has been
recorded that affects the average for that time frame irrespective of the lows for that period
11.Real Time monitoring measures actual lows and highs of exposures and weighted averages are determined.
What Lies Ahead1)Passive monitoring has been in use and is
relied upon mostly due to its lesser cost2)Long term real time results need to be
acquired and data comparisons made3)Real time monitoring shows several
promising aspects such as immediate results, thereby helping provide opportunity to mitigate in a timely manner
4)Work areas where occupational workers are present should be relied upon with real time monitors as the circumstances and environment tends to change much more rapidly
5)Perimeters and fencelines can still me monitored using passive techniques as such areas are relatively less disturbed
Detailed Info
For more info on DNRM and DNRF monitors http://www.Landauer.com For more info on Alphaguard monitors http://www.saphymo.com
ContactMasood A InayatMolycorp Inc.,67750 Bailey RoadMountain Pass, CA 923661-760-856-7661 Direct1-702-280-6023 Cell1-760-856-5610 Faxhttp://[email protected] Email.