P og ess in Nuclea Ene gy 137 (2021) 103761
A ailable online 30 Ap il 2021
0149-1970/© 2021 The Au ho s. Published by Else ie L d. This is an open access a icle unde he CC BY-NC-ND license
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Recommenda ions o he selec ion o in si u measu emen echniques o
adiological cha ac e iza ion in nuclea / adiological ins alla ions unde
decommissioning and disman ling p ocesses
Khalil Amga ou
a
, F ede ic Aspe
b
, Raquel Idoe a
c
, Ma ga i a He anz
c
,
*
a
Commissa ia `
a l’´
ene gie a omique e aux ´
ene gies al e na i es (CEA), DES/DDSD/DTPI/STRD/GRDT, Ma coule, BP 17171, 30207, Bagnols su C`
eze Cedex, F ance
b
One Technologies Di ec ion Technique, 970 Chemin des ag icul eu s, 26701, Pie ela e, F ance
c
Nuclea Enginee ing and Fluid Mechanics Depa men , Uni e si y o he Basque Coun y (UPV/EHU), Pza Ingenie o To es Que edo,1, 48013, Bilbao, Spain
ARTICLE INFO
Keywo ds:
Nuclea ins alla ions
Decommissioning and disman ling
Cons ained en i onmen s
In-si u measu emen s
ABSTRACT
In his pape , in-si u adiological cha ac e isa ion by means o non-des uc i e echniques is s udied and analysed
in he con ex o he di e en cons ained en i onmen s (iden i ied as adioac i i y, ma e ials, accessibili y and
o he haza ds) ha may be encoun e ed in he nuclea acili ies unde going decommissioning and disman ling.
As a complemen o a p e ious pape (Aspe e al., 2020), he p esen one gi es a global guidance o assis wi h he
decision making p ocess ega ding he selec ion o in-si u measu emen echniques ha could be applied in such
cons ained en i onmen s.
In addi ion, om he de ini ion o he in es iga ion objec i es, and o each one o he mos common in-si u
measu emen echniques, a b ie desc ip ion is gi en abou he impac o he abo e cons ain s and how o
in eg a e hem on o he sys em de ini ion, including he expe imen al design, he mechanical in eg a ion and he
da a managemen , o p ope ly de ine he bes adiological cha ac e iza ion me hodology.
Mo eo e , complemen ing his gene al iew, all he phases – om ini ial o inal – o a D&D p og amme we e
aken in o accoun o p o ide basic ecommenda ions, oge he wi h some pa icula disposi ions, o he
app op ia e implemen a ion o he chosen ins umen s.
S eng hs and weaknesses o he common de ec o s used o he di e en in-si u measu emen echniques, as
well as hei ecommended applica ions in nuclea acili ies a e also ou lined.
1. In oduc ion
Decommissioning and disman ling (D&D) o nuclea acili ies
(powe eac o s, uel cycle plan s, esea ch o medical accele a o s,
e c.), un il hei emedia ion and clea ance, is a global in e na ional
indus ial challenge o he XXI
h
cen u y. The s a egy o be ollowed is
speci ic o each coun y depending, amongs o he conside a ions, upon
he acili y’s cha ac e is ics, own egula o y policies, en i onmen al
p o ec ion and adioac i e was e managemen (La aia and La aia,
2012). Howe e , any D&D p og amme will esul in a olume o was e
ma e ials ha should be classi ied as adioac i e o no .
Usually, a e a i s s age o his o ical collec ion and unc ional da a,
adiological in en o y is es ablished and consolida ed wi h p elimina y
in-si u measu emen s, by means o non-des uc i e assay (NDA) ech-
niques (Amga ou and He anz, 2021). Undoub edly, his cons i u es a
complex issue conside ing he wide a ie y o s uc u es and equipmen
in ol ed, so ha hei p ope adiological cha ac e iza ion becomes a
necessa y p e equisi e o a success ul quan i ica ion o he di e en
con amina ed ma e ials (IAEA, 1998). Such a adiological cha ac e -
iza ion is also needed du ing he disman ling ac i i ies o e alua e he
e icacy o he applied decon amina ion p ocedu es and o ce i y he
inal quali y o he p oduced was e d ums. O cou se, in-si u NDA
measu emen s do no always p o ide su icien ly comple e adiological
da a and, in mos cases, hey should be complemen ed wi h labo a o y
analysis o ep esen a i e samples.
Howe e , he as majo i y o nuclea acili ies unde D&D o e
many cons ained en i onmen s, due o hei limi ed accessibili y, he
p esence o high adia ion le els, o e en he ex eme ambien condi-
ions o he oom whe e in-si u measu emen s a e o be ca ied ou .
Classi ica ion and ca ego iza ion o all hese possible cons ained
* Co esponding au ho .
E-mail add ess: [email p o ec ed] (M. He anz).
Con en s lis s a ailable a ScienceDi ec
P og ess in Nuclea Ene gy
jou nal homepage: h p://www.else ie .com/loca e/pnucene
h ps://doi.o g/10.1016/j.pnucene.2021.103761
Recei ed 23 Sep embe 2020; Recei ed in e ised o m 24 Ma ch 2021; Accep ed 23 Ap il 2021
P og ess in Nuclea Ene gy 137 (2021) 103761
2
en i onmen s has been al eady done in a p e ious pape (Aspe e al.,
2020); whe eas in his one, he abili y o he exis ing equipmen o be
used in each one o hem is analysed.
I is explained in Aspe e al. (2020) ha o each acili y subjec o a
D&D p og amme, he in es iga ion objec i es o he adiological cha -
ac e iza ion and, hence, o in-si u measu emen s, a e gi en by p oj-
ec /au ho i ies. Mo eo e , he desc ip ion and his o ical in o ma ion o
he si e a e necessa y o complemen ing he de ined in es iga ion ob-
jec i es o accomplish he decision p ocess (NEA, 2013).
Based on his p elimina y in o ma ion and he analysis o he p e-
ailing en i onmen al cons ain s, i is possible o de e mine he exac
loca ions o he necessa y in-si u measu emen s, as well as he mos
sui able equipmen and me hodologies o be used. This p ocess is named
“sys em de ini ion”. A he same ime, i is essen ial o ca y ou an
analysis o he esou ces, quali y, sa e y and secu i y issues. Such a
p ocess, which is known as “in e en ion de ini ion”, al hough i can
condi ion he inal decision abou he in-si u measu emen echnologies,
is ou side he ocus o his pape .
In his con ex , he p esen pape gi es a global guidance o assis
wi h he decision making p ocess ega ding he selec ion o he bes in-
si u measu emen echniques ha could be applied in cons ained en-
i onmen s. Fo he sake o simplici y, hese cons ained en i onmen s
a e he ea e e e ed o as “cons ain s” and hey a e iden i ied as
adioac i i y, ma e ials, accessibili y, and o he haza ds (Aspe e al.,
2020). They may indi idually a ec each in-si u measu emen ech-
nique o be used and also he in e p e a ion o he esul s ob ained.
Some la es cu ing-edge echnologies, like lase induced b eakdown
spec oscopy o LIBS (Radziemski and C eme s, 2006) and muon o-
mog aphy (Jonkmans e al., 2013) a e no discussed he e as, a leas up
ill now, hey ha e only been de eloped by a ew esea ch labo a o ies
and hey a e no commonly used in he nuclea indus y.
Fig. 1 shows a simpli ied low diag am illus a ing he key p ac ices
and a angemen s ha we ha e conside ed o he deploymen o
app op ia e in-si u measu emen echniques in cons ained en i on-
men s. All he ecommenda ions gi en in he p esen documen should
no be in e p e ed as absolu e o s ic equi emen s. The eade needs o
emembe ha hese ecommenda ions should no be aken li e ally
when applied o hei own speci ic case s udies.
In wha ollows, basic ecommenda ions a e ini ially p o ided o he
choice o in-si u measu emen echniques o each phase du ing he
whole D&D p og amme.
A e wa ds, ega ding he p oposed in-si u measu emen echniques,
he incidence on hei o e all pe o mance o he di e en cons ained
en i onmen s is highligh ed oge he wi h an explana ion o he h ee
Fig. 1. Simpli ied low diag am illus a ing he minimum a angemen s o he deploymen o app op ia e in-si u measu emen echniques o each cons ained
en i onmen .
K. Amga ou e al.
P og ess in Nuclea Ene gy 137 (2021) 103761
3
design p inciples o sys em enginee ing ha mus be en isaged o
in eg a e hese cons ain s on he de ini ion o he in es iga ion
me hodology.
Finally, some pa icula disposi ions a e o mula ed o he app o-
p ia e implemen a ion o he chosen ins umen s, as well as u he
echnical issues which he in es iga ion me hodology has o conside , in
ega d o e e y nuclea acili y oom o a ea whe e each o he majo
cons ain s ha e been iden i ied.
2. Role o in-si u measu emen s in a D&D p og amme
In-si u measu emen s oge he wi h labo a o y analysis o ep e-
sen a i e samples a e o i al impo ance h oughou he di e en
phases o a D&D p og amme. I mus be no ed ha , o a speci ic a ea,
he exis ing cons ain s (Aspe e al., 2020) could change du ing he
p og ess o hese phases and hen, he me hodologies o be used o he
co esponding in-si u cha ac e iza ion would ha e o be adap ed
acco dingly. Fo example, mos o he i adia ion cons ain s a e no -
mally p esen a he beginning and should dec ease du ing he emedi-
a ion phase un il hey ha e almos disappea ed by he end.
2.1. Ini ial – disman ling phase
One o he main objec i es in he ini ial phase o any D&D p o-
g amme is he es ima ion o he issile mass quan i y and/o he adio-
ac i e le el o exis ing was e. Fo his pu pose, in-si u adia ion
measu emen s, especially dose a e and o al gamma s eng hened wi h
some gamma- ay spec ome y o neu on assay, a e needed. Table 1
ou lines he di e en s udies ca ied ou du ing his phase as well as
hei associa ed in es iga ion objec i es and ecommended NDA
echniques.
2.2. In e media e - emedia ion phase
I conside a ion o he p ima y cha ac e iza ion leads o a decision o
unde ake emedia ion, he in e media e phase o he ongoing D&D
p og amme mus s a immedia ely. Du ing his phase, a mo e de ailed
cha ac e iza ion would be necessa y o acili a e decisions o be made
abou he app op ia e in e en ion means, and hen on u he de ails o
s eps o ha ac ion. A his s age, some in-si u measu emen s, like dose
a e and o al gamma, a e needed o allow he ull enginee ing design o
he emedia ion phase. Table 2 esumes he ecommended in-si u
measu emen echniques o each ypes o adioac i i y du ing he in-
e media e o emedia ion phase o a D&D p og amme.
2.3. Final – elease phase
The inal D&D phase occu s only a e he comple ion o all
emedia ion ac i i ies and he jus i ica ion o eaching he end s a e
a ge ed by he ope a o . This means ha bo h he conside ed si e and i s
nea en i onmen a e ully cleaned up o a p ede e mined endpoin
(un es ic ed elease o u he euse), om any dange ous and adio-
ac i e subs ance. The e o e, he inal objec i e ega ding adiological
cha ac e iza ion mus be he e alua ion o he possible p esence o e-
sidual adioac i i y in he emaining a eas and ancilla y buildings as
well as unde g ound con amina ion. The ul ima e aim o his objec i e is
o ob ain he li ing o he egula o y con ols o which a basic nuclea
ins alla ion is subjec ed o. O en, a his s age, he numbe o in-si u
measu emen s (as ecommended in Table 2) s ongly dec eases and
he majo pa o he cha ac e iza ion is ocused on he in-lab analysis,
which p o ide he lowes de ec ion limi s and he bes e iciency.
3. In eg a ing cons ain s on he sys em de ini ion
3.1. Impac o en i onmen al cons ain s
Once he exis ing impac s a e de ined o a speci ic oom, hey should
be in eg a ed in he sys em de ini ion p ocess. Table 3 gi es a b oad
indica ion on he incidence o he majo en i onmen al cons ain s on
he exis ing measu emen equipmen based on expe ience gained and
lessons lea n om pas D&D ac i i ies. The di e en le els o all po-
en ial incidences a e classi ied as ollows:
•NA when i is jus no applicable
•3 o high incidence
•2 o in e media e incidence
•1 o low incidence
•0 o no o unknown incidence
Sec ion 4 o mula es some ecommenda ions ha need o be aken
in o accoun o he app op ia e choice o he ins umen s, as well as
u he echnical issues he in es iga ion me hodology has o conside ,
in ega d o e e y nuclea acili y a ea whe e each o he majo con-
s ain s ha e been iden i ied. Al hough he e migh be he possible
p esence o o he haza ds, like chemical and/o biological ones which
basically only a ec he human in e en ion scena ios, some ecom-
menda ions ega ding his subjec a e also gi en in his sec ion.
3.2. Concep ion me hodology
Though independen ly o ganized, he h ee design p inciples o
sys em enginee ing as illus a ed in Fig. 2 a e o be in eg a ed in o a
global design p ocess o in-si u measu emen s. O all he exis ing pos-
sibili ies, only hose ha mee he iden i ied ield needs and e-
qui emen s should be chosen.
3.2.1. Expe imen al design
Expe imen al design is i s ly based on he cha ac e iza ion
Table 1
Di e en s udies ca ied ou du ing he ini ial phase o a D&D p og amme as
well as hei associa ed in es iga ion objec i es and ecommended in-si u NDA
echniques.
Needs Objec i e o he
in es iga ion
Recommended in-si u NDA
echnique
Sa e y s udies C i icali y con ol Gamma- ay spec ome y
Neu on measu emen s
Was e s udies Ve i ica ion o
adiological spec um
Radioac i e le el o
exis ing was e
Su ace con amina ion
measu emen s
Gamma- ay spec ome y
Neu on measu emen s
Radiop o ec ion
s udies
Si e ca og aphy En i onmen al adia ion
measu emen s
Su ace con amina ion
measu emen s
Disman ling scena io
s udies
Localiza ion o nuclea
ma e ial
Radia ion came as
Table 2
Recommended in-si u NDA echniques o each ype o adioac i i y du ing bo h
he in e media e and inal phases o a D&D p og amme.
Type o adioac i i y Recommended in-si u NDA
echnique
Non con amina ed su ace None
Con amina ed su ace by “d y” con amina ion (dus ,
ae osol)
Su ace con amina ion
measu emen s
Con amina ed su ace by “liquid” con amina ion
wi h no “deep pene a ion”
Su ace con amina ion
measu emen s
En i onmen al adia ion
measu emen s
Gamma- ay spec ome y
Con amina ed su ace by “liquid” con amina ion
wi h deep s uc u al pene a ion
Ac i a ed inne walls Gamma- ay spec ome y
K. Amga ou e al.
P og ess in Nuclea Ene gy 137 (2021) 103761
4
objec i es. Such an impo an s ep mus be o malized as ollows (in
o de o p io i y):
•The choice o he de ec o wi h he bes cha ac e is ics depending
mainly on he p ope ies o he measu ed objec , such as i s shape,
olume, weigh o mass densi y, ma e ial composi ion, as well as he
inne spa ial dis ibu ions o he adioac i e sou ce.
•The choice o he measu emen con igu a ion ha akes in o accoun
he cha ac e iza ion objec i es, he desi ed s a is ical p ecision, he
a ailable space, e c.
•Po en ial ins alla ion o adia ion a enua ion sc eens. This kind o
se -up is being ese ed o cases whe e he applica ion o he abo e
choices do no o e sa is ac o y esul s.
All hese echnical choices essen ially depend on he di e en con-
s ained en i onmen s, wi hou o ge ing he equi ed pa icula dis-
posi ions ha ha e o be in eg a ed on a case-by-case basis (see Sec ion
4).
3.2.2. Mechanical in eg a ion
Mechanical in eg a ion in he case o in-si u measu emen s consis s
o :
•The choice o he ca ie pla o m ( obo , d one, a icula ed a m,
special machine, e c.) acco ding o he p e iously es ablished needs
and equi emen s: en i e au onomous sys em, emo ely con olled
(ei he wi ed o wi eless), measu emen by he ope a o in he ield.
•The de ini ion o he mechanical in eg a ion o he whole sys em
acco ding o he design cons ain s ela ed o he choice o he a-
dia ion de ec o , i s associa ed elec onics and any o he componen
o de ice, i necessa y, as well as hei handling, packing, ans-
po a ion and on-si e deploymen o he whole sys em.
Some o hese echnical choices also depend on he di e en con-
s ained en i onmen s. Se e al o he ac o s ela ed o he sys em eli-
abili y, a ailabili y, main ainabili y and sa e y mus also be aken in o
accoun . In p ac ice, eliabili y depends on bo h he sys em complexi y
and he wo king en i onmen , so ha a emp s should be made o ha e
p ope combina ion o componen s, a oiding o ein o cing he c i ical
ones, in o de o educe, o he s ic es minimum, he o e all equency
o unwan ed ailu es du ing he ope a ional phase.
Table 3
Impac o he majo en i onmen al cons ain s on in-si u measu emen echniques.
En i onmen al cons ain
NDA echnique
Radia ion Ma e ials Accessibili y
Ai Liquid O he s
Con amina ion Gamma
Dose a e
Neu on
Dose a e
Radia ion
lux
P essu e Tempe a u e Flow Imme si e humidi y Me al Conc e e Co ido s/
Tunnel
Heigh Clu e Subsu ace
En i onmen al adia ion
measu emen s
1 3 3 3 0
a
0
a
0 NA 0
a
1 2 1 0 2 3
Su ace con amina ion
measu emen s
3 1 1 1 0 0 1 NA 2 1 2 0 0 2 NA
Gamma- ay spec ome y 1 3 1 2 0 1 0 1 2 1 1 2 2 2 3
Neu on measu emen s 0 3 3 2 0 1 0 3 2 0 2 1-3
b
1-3
b
1-3
b
3
Radia ion came as 0-1
b
2 1 2 0 1 0 NA 0 0 0 1-3
b
1-3
b
1-3
b
3
a
In he case o ai -ke ma measu emen s associa ed co ec ion ac o s mus be applied.
b
Depending on he ype and/o he size o he ins umen used.
Fig. 2. Design p inciples o sys em enginee ing applied o in-si u
measu emen s.
K. Amga ou e al.
P og ess in Nuclea Ene gy 137 (2021) 103761
5
3.2.3. Da a managemen
The e m “da a managemen ” includes secu e communica ion wi h
all he deployed de ices and senso s oge he wi h da a ga he ing,
ans e , p ocessing and s o age.
In no case should da a managemen neglec he co ec choice o he
in e p e a ion me hod and he quali y o he measu emen s. This means
ha i has o cons an ly con empla e he ollowing aspec s:
•The de ini ion o he in e p e a ion me hodology, which is in insi-
cally linked o he sys em design o he de ice and i mus be
conside ed as a key s ep in he success o in-si u measu emen s. Such
an in e p e a ion is mos o en based on assump ions and good
p ac ices aken by conside ing he his o y o he i em o be
cha ac e ized.
•The s a egic app oach o educe and e alua e unce ain ies. Abo e
all, hei iden i ica ion a he ini ial s age makes i possible o
o malize all he assump ions ega ding he sys em design and o
in eg a e hem nume ically in o he inal esul s.
On-si e deploymen in he majo i y o nuclea acili ies equi es as
and eliable indoo wi eless bidi ec ional ne wo ks. Ad an ages o a Li-
Fi connec ion (Dimi o and Haas, 2015) in enclosed spaces wi h espec
o he Wi-Fi one a e: a wide bandwid h ( om in a ed o ul a iole ); i
can ope a e in elec omagne ic sensi i e a eas (no e en he cause o
such in e e ences); i is almos hund ed imes as e ; and in p inciple
wi h no limi s o capaci y.
4. Pa icula disposi ions
4.1. En i onmen al adia ion measu emen s
This sec ion is mainly ocused on en i onmen al measu emen s o
he X/γ adia ion. Such measu emen s may include g oss coun ing, ai -
ke ma o H*(10) moni o ing. Al hough H*(10) measu emen s may also
be pe o med o neu ons in some ci cums ances, all he cons ain s
in luencing his kind o measu emen a e discussed sepa a ely in Sec ion
4.4 oge he wi h hose associa ed o he neu on coincidence coun ing
mode.
Table 4 summa izes he s eng hs and weaknesses o he common
de ec o s used o en i onmen al adia ion measu emen s as well as
hei ecommended applica ions in nuclea acili ies subjec o a D&D
p og amme.
4.1.1. Radioac i i y cons ain s
4.1.1.1. Radia ion
4.1.1.1.1. Iden i ica ion o cons ain s. A measu emen in high dose
a e en i onmen s is e y challenging when using gas- illed de ec o s
and can be a ec ed in se e al ways, such as signal disc imina ion,
de ec ion pe o mance, dead (o esol ing) ime issues and backg ound
co ec ion.
In si ua ions o ele a ed coun a es, p oblems o he loss o linea i y
ollowed by a comple e sa u a ion o pa alysis (i.e., he illing gas e-
mains pe manen ly ionized) o he de ec o used could occu , equi ing
e y ca e ul choice o i s in insic o se ing pa ame e s (i.e., ope a ing
ol age, empe a u e and gas p essu e) and i s associa ed elec onics
(Usman and Pa il, 2018).
In addi ion, exposu e o ex emely high lux o neu ons, cha ged
pa icles and e y ene ge ic pho ons (i.e. abo e 10 MeV) may se iously
damage elec onic componen s o comp omise hei cha ac e is ics, hus
leading o a d as ic dec ease in he de ec o li e ime. In such i adia ion
ci cums ances, o ganic insula o s may also b eak down.
4.1.1.1.2. In eg a ion o cons ain s on he ins umen design. In
p inciple, e y compac gas- illed de ec o s can be used o challenge
high adia ion dose a es, bu hose based on silicon PIN diodes also
cons i u e a good al e na i e. This is pa icula ly impo an o back-
g ound le el s udies and eal- ime epo ing o any ab up ele a ion in
his le el o he i s esponde s. Fas esponse, low ope a ing ol age,
low powe consump ion, po abili y, compac ness and p ac ically un-
limi ed ope a ing li e make hem be e adap ed in such ci cums ances.
Fo example, he employmen o ene gy-compensa ed Si-based de ec o s
p o ides a mo e o less la esponse o e a wide pho on ene gy ange
(60–1250 keV) and can ole a e adia ion dose a es going beyond 20
Gy/h (Mi a e al., 2016).
4.1.1.1.3. In eg a ion o cons ain s on he inal mechanical design. I
may be necessa y o implemen shielding and collima ion mechanisms
wi h small opening angles in o de o es ic he ield-o - iew o he
chosen ins umen s, p e e ably o e y educed-size, o only speci ic
a eas o po ions o he i em o be measu ed. The acquisi ion can
he e o e be pe o med a di e en posi ions a ound he objec
p o iding a high deg ee o p ecision. The ex a possibili y, in he case o
ioniza ion chambe s and p opo ional coun e s, o only conside ing low
inne gas p essu e mus also be en isaged.
Fu he mo e, he complemen a y deploymen o a emo ely mobile
pla o m, such as a obo o d one, wi h inc eased adia ion ole ance o
bo h i s mechanical and elec onic componen s, is also a good al e na-
i e (Tsi simpelis e al., 2019).
4.1.1.2. Con amina ion. Mos o he a ailable de ec o s o en i on-
men al adia ion measu emen s, excep pe haps hose ha ing a hin end-
window, a e adequa ely p o ec ed agains he po en ial p esence o
ai bo ne adionuclides and hei ou e su aces e ec i ely acili a e
hei p ope cleaning a e each use. Some imes hei addi ional p o-
ec ion wi hin plas ic bags can be coun e p oduc i e as i may ei he
block hei in e nal hea exhaus o p oduce mo e a enua ion phe-
nomenon, especially o β-pa icles and low-ene gy X/γ adia ion.
4.1.2. Ma e ials cons ain s
4.1.2.1. Ai . Ai -ke ma measu emen s a e no i ial and se e al
co ec ion ac o s mus always be conside ed, namely he ones associ-
a ed o he possible a ia ions wi h espec o he ai p essu e and
empe a u e unde which he de ec o calib a ion was ca ied ou .
In addi ion, big changes ega ding he ai densi y has a non-
negligible impac on he o e all pe o mance o he o he de ec o s
hus leading o la ge unce ain ies and da a misin e p e a ion, mainly
when measu ing weakly pene a ing adia ion.
I should also be bo ne in mind ha insula ion o con en ional cables
and BNC connec o s as well as mos o he elec onic componen s end o
ail a c i ical empe a u es. Fo example, when hey a e le nea
hea ing elemen s, sun-wa med su aces, adia o s and la ge cooling
machines. Al e na i ely, a empe a u e compensa ion sys em can also be
implemen ed on de ec o s and hei associa ed elec onics.
4.1.2.2. Liquid. Acco ding o Radia ion P o ec ion ules, he e is no
need o in e es o pe o m en i onmen al measu emen s unde liquid
imme sion condi ions as bo h H*(10) and ai -ke ma ope a ional quan-
i ies o ex e nal exposu es o ionizing adia ion a e de ined and cali-
b a ed conside ing only a ee-in-ai geome y con igu a ion.
In addi ion, conside ing wha has been said in he p e ious Sec ion,
ano he co ec ion ac o mus be applied when measu ing ai -ke ma in
e y humid a mosphe es.
Spu ious pulses o abou he same size as hose om he eal signal
can some imes appea and a e due o luc ua ions in leakage cu en s
h ough insula o s, pa icula ly unde high humidi y en i onmen s
(Knoll, 2010).
4.1.2.3. Consis ency. In gene al, in-si u measu emen s o bulky adio-
ac i e ma e ials a e se iously a ec ed by unce ain ies on he cha ac-
e is ics o he de ec o used, on he p ope ies o he measu ed objec , as
K. Amga ou e al.
P og ess in Nuclea Ene gy 137 (2021) 103761
6
al eady s a ed in Sec ion 3.2.1, and on he conside ed geome ic
con igu a ion o he whole scene unde s udy. The e o e, hey need a
se ies o heo e ical simula ions in a way o calcula e ad hoc ans e
unc ions and o co ec ly e alua e all he unce ain ies ha ha e a
wide in luence on he inal esul s.
Howe e , as nuclea acili ies con ain huge s uc u es and complex
equipmen , p oducing accu a e models becomes ex emely di icul
because in mos ci cums ances such de ailed in o ma ion is missing. In
ha case, se e al hypo hesis, as ealis ic as possible, mus be conside ed,
aking in o accoun he a ailable his o ical knowledge (e en when
incomple e) and hei plausibili y has o be checked by compa ing he
associa ed esul s ob ained om a leas wo di e en in-si u measu e-
men echniques each ime.
4.1.3. Accessibili y cons ain s
4.1.3.1. Na ow o clu e spaces. The possible deploymen o a
emo ely mobile pla o m, based on educed-size de ec o s and
equipped wi h he necessa y senso s (posi ion, mo ion, inclina ion,
p oximi y), would allow access o hose spaces wi h e y limi ed
accessibili y (Tsi simpelis e al., 2019).
As an example o bes p ac ice in his domain, gi en he need o
ensu e a equen ba e y echa ging o such a mobile pla o m ope -
a ing in di icul access a eas, Ishida and Fu ukawa (2015) de eloped a
me hod o ansmi ing elec ical powe h ough hick conc e e walls,
based on magne ic esonance coupling, wi hou he need nei he o
labo iously d illing holes in hem no o e en ual ou ing o cables
(o en o e long dis ance co ido s) om one side o ano he .
In line wi h his, a sel -powe ed wi eless sys em o ul asonic da a
ansmission has ecen ly been designed (Wu e al., 2019) o be applied
unde e y ha sh en i onmen s in almos all he enclosed s uc u es o
nuclea acili ies. To success ully add ess hese kind o p oblema ic as-
pec s, i may be help ul o consul he e iew ca ied ou by Yang e al.
(2015) abou he cu en iable echnologies o powe and communica e
wi h hidden senso s behind me allic ba ie s.
Table 4
S eng hs and weaknesses o he common de ec o s used o en i onmen al adia ion measu emen s as well as hei ecommended applica ions in nuclea acili ies
subjec o a D&D p og amme.
DETECTOR TYPE STRENGTHS WEAKNESSES WHERE TO APPLY
Ioniza ion chambe s •can be made o ha e a e y good X/γ
ene gy and pola esponse as also
accep able β cha ac e is ics
•no p oblems wi h pulsed ields
•good dynamic ange o dose a es,
ypically 2
μ
S h
−1
up o 10 S /h
•can use small pola ising ba e ies
• e y low signal le el a no mal adia ion p o ec ion
dose a es leading o s a is ical luc ua ions o slow
esponse imes
•gene ally unusable below 2
μ
S h
−1
•suscep ible o empe a u e and humidi y co ec ions
• equi es ca e ul use and good main enance,
pa icula ly egula d ying o desiccan
•expensi e
•almos all nuclea acili y a eas and equipmen
excep he ones unde liquid imme sion condi ions
P opo ional coun e s •good X/γ ene gy esponse down o 30 keV
•use ul be a esponse a highe ene gies
•gene ally sa is ac o y wi h pulsed ields
•high de ec ion e iciency
•wide dynamic ange o useable dose a es
by a ying he gas ampli ica ion o he
pola izing ol age
• ela i ely ulne able de ec o , o he β e sions
•uses a e y high pola ising ol age
•expensi e
•suscep ible o high ol age a ia ion
•pulse pile-up e ec a in ense adia ion ields
•almos all nuclea acili y a eas and equipmen
excep he ones unde liquid imme sion condi ions
and a high adia ion gamma dose a es and
adia ion luxes
Ene gy-compensa ed
GM de ec o s
• e y easy o p ocess signal
•wi h a mo e o less (±30%) la ene gy
esponse in e ms o H*(10)
•much mo e sensi i e han an ioniza ion
chambe , a olume o 10 cm
3
has he same
de ec ion e iciency as an ioniza ion
chambe o 300 cm
3
•s able and long ope a ing li e, i
physically undamaged
•low cos
• ugged
•no use ul β esponse
•X/γ esponse ha alls apidly below ~50 keV
•se iously a ec ed by pulsed ields, un us wo hy
when he coun a es exceed abou 35% o he pulse
a e om a machine p oducing na ow (
μ
s) pulses
•dead ime e ec a in ense adia ion ields
•almos all nuclea acili y a eas and equipmen
excep he ones wi h pulsed ields o unde liquid
imme sion condi ions
Thin end-window,
ene gy-
compensa ed GM
de ec o s
• e y good X/γ ene gy esponse om 10 o
15 keV upwa ds o 1.25 MeV
•good pola esponse
•ins umen s whe e he il e can be emo ed so ha
he de ec o can be used as a con en ional end-
window de ec o a e suscep ible o physical damages
•dead ime e ec a in ense adia ion ields
•almos all nuclea acili y a eas and equipmen
excep he ones wi h high dose a es o unde
liquid imme sion condi ions. Pay special a en ion
o co osi e chemical compounds ha can easily
a ec de ec o windows.
Thin end-window GM
de ec o s
• espond o X/γ adia ions om 5 keV
upwa ds and o all β adia ion which
con ibu es o ambien o di ec ional dose
equi alen a e
•good pola esponse (“pancake” ypes)
• e y ulne able when used wi h he end-window
unp o ec ed, i.e. o measu e β-pa icles and/o e y
low ene gy X/γ adia ion, subsequen physical
damage is gene ally a al and canno be epai ed
•mus be p o ec ed wi h a ine e ched me al o plas ic
g ill
•poo ene gy- esponse
•dead ime e ec a in ense adia ion ields
• e y hin de ec o windows can easily be a ec ed by
co osi e chemical compounds
•almos all nuclea acili y a eas and equipmen
excep he ones wi h high dose a es o unde
liquid imme sion condi ions
Plas ic scin illa ion
de ec o s
•good X/γ ene gy and pola esponse down
o 20 keV o ins umen s wi h smalle
scin illa o s and hin cans
•high de ec ion e iciency
•backg ound ejec ion
•good dynamic ange by a ying he
pola izing ol age
•easy o p oduce a loga i hmic dose a e
esponse
•la ge de ec o (scin illa o and pho omul iplie ube)
•expensi e
•pulse pile-up e ec as well as in insic de ec s and/o
ailu es a in ense adia ion ields
•almos all nuclea acili y a eas and equipmen
excep he ones unde liquid imme sion condi ions
K. Amga ou e al.
P og ess in Nuclea Ene gy 137 (2021) 103761
7
4.1.3.2. Heigh . Access o g ea heigh s may need he use o d ones, li
gea s, elescopic ubes o ex ension a ms. One impo an aspec o
highligh is ha he addi ional use o he shields and collima o s, i
needed, will add oo many complica ions due o hei weigh and size.
4.1.3.3. Subsu ace. En i onmen al measu emen s h oughou deeply
con amina ed a eas o soils may be e y sui able ini ially o ha e an idea
abou he po en ial p esence o adioac i e singula i ies o ho spo s, and
can be oughly co ela ed wi h he ac i i ies o he majo gamma- ay
emi ing adionuclides.
4.1.4. O he haza ds
The deploymen o an unmanned mobile pla o m can also be o
g ea u ili y o co ec ly con ol he ai quali y as well as o de ec he
p esence o oxic, lammable o combus ible a mosphe es and o he
dange ous agen s in emo e a eas, hus a oiding any unnecessa y isk o
human exposu e.
The p esence o co osi e chemicals may also a ec he pe o mance
o he adia ion de ec o s and ex eme a en ion mus be paid o he ones
he me ically sealed wi h plas ic ma e ials o using a hin end-window, in
o de o measu e weakly pene a ing adia ion.
4.2. Su ace con amina ion measu emen s
The ollowing ables (Tables 5 - 7) summa ize he s eng hs and
weaknesses o he common de ec o s used o su ace con amina ion
measu emen s as well as hei ecommended applica ions in nuclea
acili ies subjec o a D&D p og amme.
4.2.1. Radioac i i y cons ain s
4.2.1.1. Radia ion. P opo ional coun e s, which can be used o con ol
he adioac i e con amina ion on su aces, o e he possibili y o
dis inguish he alpha-induced pulses om he be a ones by simply
adjus ing he bias ol age. In ac , pulse pile-up e ec due o high le els
o adia ion can al e peak ampli udes and educe he e ec i eness o
he c oss alk o spill o e co ec ions ha accoun o he disc imina ion
o signals and hei co ec assignmen . All hese signal disc imina ion
p oblems may lead o p oblems ela ed o he e iciency calib a ion
(Knoll, 2010).
In hose a eas wi h ex eme le els o adia ion, su ace con amina-
ion can ha dly be e alua ed by di ec me hods. The only way in his
case would be by aking smea samples om each suspec ed con ami-
na ed a ea, by means o a emo ely obo p e e ably unde wi eless
mode, and measu ing, once eco e ed back in a sa e oom, i s associa ed
emo able con amina ion wi h he app op ia e ins umen s as lis ed in
he abo e ables. Ne e heless, he use o d ones in such ci cums ances
has o be s ic ly o bidden since hei p opelle s a e able o e-suspend
con amina ing pa icles in he ai and he ex en o su ace con amina-
ion o o he a eas o objec s, which we e o iginally clean enough o be
Table 5
S eng hs and weaknesses o he common de ec o s used o su ace con amina ion measu emen s, in he case o
α
-pa icles, as well as hei ecommended applica ions
in nuclea acili ies subjec o a D&D p og amme.
DETECTOR TYPE STRENGTHS WEAKNESSES WHERE TO APPLY
Solid s a e de ec o s • e y good de ec ion e iciency
•ul a ligh weigh and compac
•ex emely suscep ible o elec omagne ic
in e e ence
• end o be mic ophonic
•expensi e
• agile
•can be sensi i e o β, γ and neu ons
•pulse pile-up e ec as well as in insic de ec s
and/o ailu es a in ense adia ion ields
•almos all nuclea acili y a eas and equipmen
excep he ones wi h elec omagne ic
in e e ence o unde liquid imme sion
condi ions
•conside ing only smoo h and impe meable
su aces
ZnS scin illa ion de ec o s •good de ec ion e iciency, he majo i y o
α
-pa icles ha pene a e he window wi h
signi ican ene gy will be coun ed
•a ailable in a wide ange o sizes
• easonable β, X and γ ejec ion al hough
ul ima ely ei he alse coun s will be eco ded a
high dose a es o he de ec o will ail o
dange
•ligh weigh , mos o hem use sepa a e p obes
•low in insic backg ound
•easy se ing up p ocedu e
•ex emely ulne able, unlike he scin illa o
and pho omul iplie combina ion, he delica e
and expensi e pa is jus behind he window
•can be sensi i e o β, γ and neu ons
•pulse pile-up e ec as well as in insic de ec s
and/o ailu es a in ense adia ion ields
•almos all nuclea acili y a eas and equipmen
excep he ones unde liquid imme sion
condi ions
•conside ing only smoo h and impe meable
su aces
Dual phospho
scin illa ion p obes
(ZnS on plas ic
scin illa o )
•good de ec ion e iciency, as o s anda d
α
pulses
•use ul o mixed
α
and high o in e media e
ene gy β con amina ion
•ligh weigh
•easy window epai
•may no ole a e high magne ic ields, unless
using a p ope Mu-me al shielding
•can be sensi i e o β, γ and neu ons
•pulse pile-up e ec as well as in insic de ec s
and/o ailu es a in ense adia ion ields
•almos all nuclea acili y a eas and equipmen
excep he ones wi h high magne ic ields o
unde liquid imme sion condi ions
•conside ing only smoo h and impe meable
su aces
Thin end-window GM
de ec o s
•la ge, easily p ocessed pulse
• e y simple se ing up p ocedu e
•consis en ope a ing ol age and adia ion
cha ac e is ics
•lowes cos o e all op ion in mos
ci cums ances
•ligh and compac
•small “pancake” GMs a e easonably cheap
•ex emely agile
•backg ound coun - a es gene ally oo high
•no disc imina ion agains o he adia ions
•dead ime e ec a in ense adia ion ields
•almos all nuclea acili y a eas and equipmen
excep he ones wi h high a es o unde liquid
imme sion condi ions
•conside ing only smoo h and impe meable
su aces wi hou co osi e chemical compounds
Thin end-window gas-
illed p opo ional
coun e s
• e y good de ec ion e iciency.
• i ually any
α
pa icle passing h ough he
window wi h an ene gy in excess o 0.5 MeV
will be coun ed
•a ailable in e y la ge sizes, i equi ed
•possible disc imina ion agains β-pa icles
•easy window epai
•consis en ope a ing po en ial
•no in luenced by magne ic ields
•ex emely agile
• he uni o mi y o he la ge de ec o s can be
poo , wi h a low esponse o ac i i y in he
de ec o co ne s
•can be sensi i e o γ and neu ons
•pulse pile-up e ec a in ense adia ion ields
•almos all nuclea acili y a eas and equipmen
excep he ones wi h high dose a es o unde
liquid imme sion condi ions
•conside ing only smoo h and impe meable
su aces wi hou co osi e chemical compounds
K. Amga ou e al.
P og ess in Nuclea Ene gy 137 (2021) 103761
8
Table 6
S eng hs and weaknesses o he common de ec o s used o su ace con amina ion measu emen s, in he case o β-pa icles, as well as hei ecommended applica ions
in nuclea acili ies subjec o a D&D p og amme.
DETECTOR TYPE STRENGTHS WEAKNESSES WHERE TO APPLY
Scin illa ion de ec o s •a ailable in a wide ange o sizes
•good sensi i i y
•can co e a wide ange o ene gies
•window easily eplaced
•ligh weigh
•easy se ing up p ocedu e
•suscep ible o magne ic in e e ence,
unless using a p ope Mu-me al shielding
• agile
•can be sensi i e o γ and neu ons
•pulse pile-up e ec as well as in insic
de ec s and/o ailu es a in ense
adia ion ields
•almos all nuclea acili y a eas and equipmen excep
he ones wi h magne ic in e e ence o unde liquid
imme sion condi ions
•conside ing only smoo h and impe meable su aces
Thin end-window gas- illed
p opo ional coun e s
•a e y good de ec ion e iciency down
o
14
C (i.e., β-pa icles wi h E
max
≥156
keV)
•a ailable in e y la ge sizes, i equi ed
•easy window epai
•consis en ope a ing po en ial
•no in luenced by magne ic ields
•good
α
ejec ion
• e y a iable ope a ing po en ial wi hin
any one ype
• agile
•can be sensi i e o γ and neu ons
•pulse pile-up e ec a in ense adia ion
ields
•almos nuclea acili y a eas and equipmen excep he
ones wi h high dose a es o unde liquid imme sion
condi ions
•conside ing only smoo h and impe meable su aces
wi hou co osi e chemical compounds
Thin i anium window xenon-
illed sealed p opo ional
coun e s
•use ul o β and low ene gy X/γ
adia ion
• ela i ely ough window
•ligh weigh
•no gas illing equi ed
•consis en ope a ing po en ial and
adia ion cha ac e is ics
• equi e high ol age
•uni o mi y o la ge de ec o s can be
poo
•can be sensi i e o γ and neu ons
•pulse pile-up e ec a in ense adia ion
ields
•almos all nuclea acili y a eas and equipmen excep
he ones wi h high dose a es o unde liquid imme sion
condi ions
•conside ing only smoo h and impe meable su aces
wi hou co osi e chemical compounds
Thin end-window GM de ec o s •la ge, easily p ocessed pulse
• e y simple se ing up p ocedu e
•consis en ope a ing ol age and
adia ion cha ac e is ics
•lowes cos o e all op ion in mos
ci cums ances
•ligh and compac
•small “pancake” GMs a e easonably
cheap
•no alpha disc imina ion unless in ‘dual
phospho p obe’ o m
• agile
•can be sensi i e o γ and neu ons
•dead ime e ec a in ense adia ion
ields
•almos all nuclea acili y a eas and equipmen excep
he ones wi h high dose a es o unde liquid imme sion
condi ions
•conside ing only smoo h and impe meable su aces
wi hou co osi e chemical compounds
Thin walled GM de ec o s •mo e obus han he hin window
a ie y
•la ge use ul a ea han he hin
window a ie y
• e y simple se ing up p ocedu e
•consis en ope a ing ol age and
adia ion cha ac e is ics
•low cos
•ligh
•expensi e
•no app op ia e o low-ene gy
β-pa icles (E
max
<0.5 MeV)
• equi e egula e eshing wi h coun ing
gas
•can be sensi i e o γ and neu ons
•dead ime e ec a in ense adia ion
ields
•almos all nuclea acili y a eas and equipmen excep
he ones wi h high dose a es o unde liquid imme sion
condi ions
•conside ing only smoo h and impe meable su aces
wi hou co osi e chemical compounds
Table 7
S eng hs and weaknesses o he common de ec o s used o su ace con amina ion measu emen s, in he case o X/γ adia ion, as well as hei ecommended ap-
plica ions in nuclea acili ies subjec o a D&D p og amme.
DETECTOR TYPE STRENGTHS WEAKNESSES WHERE TO APPLY
Thin end-window
compac sodium
iodide scin illa ion
de ec o s
•small c ys al size is a e y e icien X/γ
adia ion, o he 3 mm hickness he de ec ion
p obabili y is g ea e han 0.5 o no mal
inciden adia ion up o 120 keV
•a ypical aluminium window o 14 mg cm-2
hick has a ansmission o a leas 0.8 o
no mal inciden X/γ adia ion down o 10 keV
• o a be yllium window o 46 mg cm-2 hick,
he ansmission a no mal incidence is a leas
0.8 down o 5 keV
• he combina ion o he p ope scin illa o and
window hus o e s a e y e icien de ec o
o e a wide ene gy ange
• he scin illa o is e y b i le and easily c azes
wi h mechanical shock
•can be sensi i e o neu ons
•pulse pile-up e ec a in ense adia ion ields
•almos all nuclea acili y a eas and
equipmen excep he ones wi h high dose
a es, excessi e oom empe a u e a ia ions o
unde liquid imme sion condi ions
•conside ing only smoo h and impe meable
su aces
Ti anium end-window
xenon- illed
p opo ional coun e s
•use ul o β and low ene gy X/γ adia ion
• ela i ely ough window
•ligh weigh
•no gas illing equi ed
•consis en ope a ing po en ial and adia ion
cha ac e is ics
•end-window can be physically damaged, which i
no ca e ully epai ed will lead o a g adual
de e io a ion o he scin illa o , esul ing in an
inc ease in he ene gy h eshold
•can be sensi i e o neu ons
•pulse pile-up e ec a in ense adia ion ields
•almos all nuclea acili y a eas and
equipmen excep he ones wi h high dose a es
o unde liquid imme sion condi ions
•conside ing only smoo h and impe meable
su aces wi hou co osi e chemical
compounds
K. Amga ou e al.
P og ess in Nuclea Ene gy 137 (2021) 103761
9
classi ied as con en ional was e.
4.2.1.2. Con amina ion. Su ace con amina ion measu emen s need o
be as close as possible (no mo e han a ew mm) o he objec unde
examina ion and special ca e mus be aken o no con amina e he
de ec o i sel . In addi ion, because o he ex emely low pene a ion o
alpha pa icles, an ul a- hin ba ie mus be conside ed o allow he
pa icles o en e he ac i e egion o he de ec o , while simul aneously
p o ec ing his la e . Mos imes, a de ec o wi h an end-window, made
o an aluminized Myla o mica ilm (~0.8 mg/cm
2
), is used and hus
any e en ual con ac wi h ha d objec s may punc u e i .
4.2.2. Ma e ials
4.2.2.1. Ai . Almos he same as o en i onmen al adia ion mea-
su emen s (see Sec ion 4.1.2.1).
4.2.2.2. Liquid. Such a cons ain is no applicable o su ace
con amina ion measu emen s.
4.2.2.3. Consis ency. When a adioac i e subs ance has been able o
ully in il a e, somehow o o he , inside po ous ma e ials o he ones
wi h s uc u al c acks, like in a conc e e wall, i s su ace con amina ion
measu emen s a e no longe alid. They should in consequence be
es ic ed, especially in he case o
α
-pa icles, o only smoo h and
impe meable su aces.
4.2.3. Accessibili y
4.2.3.1. Na ow and/o clu e spaces. The possible deploymen o a
emo ely and well-equipped obo (a d one canno be used o he same
easons explained in Sec ion 4.2.1.1), p e e ably unde wi eless mode,
could be en isaged o con ol he ex en o su ace con amina ion in
di icul access ooms.
4.2.3.2. Heigh . Same ecommenda ion as in Sec ion 4.1.3.2 bu no
conside ing he d one op ion (see explana ion in Sec ion 4.2.1.1).
4.2.3.3. Subsu ace. Such a cons ain is no applicable o su ace
con amina ion measu emen s.
4.2.4. O he haza ds. Same ecommenda ion as in Sec ion 4.1.4 bu no
conside ing he d one op ion (see explana ion in Sec ion 4.2.1.1).
4.3. Gamma- ay spec ome y
Table 8 summa izes he s eng hs and weaknesses o he common
γ-spec ome y de ec o s as well as hei ecommended applica ions in
nuclea acili ies subjec o a D&D p og amme. The e a e ob iously
many o he de ec o s o he same amilies (i.e., ino ganic scin illa o s
and semiconduc o s) bu hei beha iou does no di e a lo om hose
al eady men ioned in his able.
4.3.1. Radioac i i y cons ain s
4.3.1.1. Radia ion
4.3.1.1.1. Iden i ica ion o cons ain s. When a gi en gamma- ay
spec ome e is exposed o in ense adia ion ields dead ime and
pulse pile-up e ec s may occu (Usman and Pa il, 2018). Se e al ha d-
wa e and so wa e me hods a e a ailable o educe o o co ec hese
e ec s in ce ain ci cums ances, bu hey shall be conside ed in ad ance
when unde aking he sui able selec ion o de ec ion sys ems. Some
de ec o s ha e e y low associa ed dead ime, like o ganic scin illa o s
(Knoll, 2010; Tsoul anidis and Landsbe ge , 2015).
In addi ion, exposu e o ex emely high lux o neu ons cha ged
pa icles and e y ene ge ic pho ons (i.e. abo e 10 MeV) may cause
se e al in insic de ec s and/o ailu es (la ice displacemen s, deep-
le el aps, gli ches, pa asi ic s uc u es, single e en s, e c.) in bo h
ino ganic scin illa o s and semiconduc o s and associa ed elec onics
he e o e a ec ing hei de ec ion p ope ies.
Ano he key issue al eady highligh ed by Aspe e al. (2020), e e s o
he backg ound co ec ion p oblem liable o be al e ed a high dose
a es, hus implying an inc ease in coun s unde he o al abso p ion
peaks co esponding o he adionuclides o in e es . Mo e in e e ence
phenomena can also a ise as a esul o he in e ac ion o p ima y X- o
γ- ays wi h he s uc u al and shielding ma e ials a ound he de ec o ,
h ough p ocesses like Comp on back-sca e ing, B emss ahlung adi-
a ion, seconda y annihila ion 511 keV pho ons a e elec on-posi on
pai p oduc ion and cha ac e is ic X- ays issued om he pho oelec ic
e ec . They a e expec ed o inc ease wi h he ac i e olume o he de-
ec o and, depending on he ene gy esolu ion o his la e , hey can
p e en he appea ance o some less in ense peaks o he analysed
adionuclide sou ce. In some cases, he p esence o high lux neu ons
may ac i a e he de ec o ma e ial, e en ually emi ing new X- o γ- ays
ha can once again in e e e wi h he measu ed spec um (Bagino a
e al., 2018).
4.3.1.1.2. In eg a ion o cons ain s on he ins umen design. Dedi-
ca ed digi al signal p ocessing equipmen and algo i hms can be used o
au oma ically co ec , e en pa ially in some ex eme si ua ions, bo h
he dead ime and pulse pile-up e ec s (S anneby and Walke , 2004).
Whe eas mos o he abo e in insic ailu es can be p e en ed by
using adia ion- ole an and edundan in eg a ed ci cui s (Calliga o
and Ga i, 2018), some o he c ys al de ec s like la ice displacemen s
can be epai ed a e he measu emen h ough he so-called annealing
p ocess (Peplowski e al., 2019). Tha is a kind o “ ese ” du ing which
he de ec o needs o be hea ed a a empe a u e a ound 100 ◦C o some
ime (no mally se e al days) and le a e wa ds as long as necessa y o
co ec ion o such de ec s.
4.3.1.1.3. In eg a ion o cons ain s on he inal mechanical design.
The possibili y o using low-noise cha ge p eampli ie (Pullia e al.,
2005) allowing he emo e con ol om la ge dis ances o he de ec o
wi h adequa e shielding and collima ion canno be excluded.
Fu he mo e, as al eady s a ed be o e o o he measu ing equip-
men , he complemen a y deploymen o a emo ely mobile pla o m,
wi h inc eased adia ion ole ance o bo h i s mechanical and elec onic
componen s, is also a good al e na i e.
4.3.1.2. Con amina ion. All p e en i e ac ions need o be aken when
he e is a minimal possibili y o adioac i e con amina ion o he de-
ec o . Fo his eason, only hose measu emen ins umen s no using an
in e nal an mechanism o cool down hei uni head ha e o be a -
ou ed. Fo p ac ical conside a ions, e en he use o liquid ni ogen, CFC,
o any o he e ige an ( lammable o no ) mus be s ic ly o bidden.
Fo example, an HPGe de ec o coupled o a pulse- ube c yocoole can
be conside ed as he only choice among he e ige a ion possibili ies.
Addi ional p o ec ion solu ion is achie ed h ough con inemen o bo h
he de ec o and i s elec onics wi hin plas ic bags. Howe e , as al eady
s a ed in Sec ion 4.1.1.2, his way o p o ec ing om con amina ion can
be coun e p oduc i e as i may ei he block hei in e nal hea exhaus
o p oduce mo e a enua ion phenomenon o low-ene gy X- and γ- ays.
This is he case o scin illa ion de ec o s, leading o p oblems ela ed o
an adequa e ene gy and FWHM calib a ion (Ahmed, 2007).
4.3.2. Ma e ials
4.3.2.1. Ai . Ino ganic c ys al de ec o s may show a gain d i due o
empe a u e a ia ions. In ac , hey a e usually coupled o a pho o-
mul iplie ube, which is highly sensi i e o empe a u e changes, as
well as o s ay magne ic ields. Al hough, when using a he a silicon
a alanche pho odiode, his la e is also p e en ed in ope a ions a
ele a ed empe a u es (Knoll, 2010).
K. Amga ou e al.
