ML19345D757
| ML19345D757 | |
| Person / Time | |
|---|---|
| Issue date: | 12/01/1980 |
| From: | Schroeder F Office of Nuclear Reactor Regulation |
| To: | Goller K NRC OFFICE OF STANDARDS DEVELOPMENT |
| References | |
| RTR-REGGD-08.014, RTR-REGGD-8.014, TASK-OH-940-4, TASK-OS NUDOCS 8012160561 | |
| Download: ML19345D757 (13) | |
Text
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<>g.o/y c S o / e f THIS DOCUMENT CONTAINS i
P00R QUAUTY PAGES DEC 011990 g
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PM y.a f!EMORAMDUt1 FOR: Karl R. Goller, Director IM Division of Siting, Healtn, and Safeguards Standaros.
31 C
Office of Standards Development f@
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n FRON:
Frank Schroeder, Acting Director M
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Division of Safety Technology
+
Office of Nuclear Reactor Regulation SUBJ ECT:
REVIEW 0F DRAFT REGULATORY GUIDE 8.14 REVISION 2
" PERSONNEL NEUTRON DOSIMETERS" In response to a memorandum dated 10/9/80 from J. Guibert, we have reviewed the subject document for need, technical content, implementation guidance,
_ and value/ impact.
Enclosed is a marked-up copy of the document. Our concerns are basically directed towards the conclusions reached by S.D: from the research performed by Rensselaer Polytechnic Institute and Battelle Pacific Northwest Laboratory.
He are not in complete agreement with the manner in which the calculational methods for dosimetry have been addressed in the guide as acceptable alter-natives for perscnnel neutron dosimetry. Clarification of our position with respect to these methods, as compared to the albedo technique for personnel monitoring, have been discussed with Nancy Dennis who is the new S.D. Task Leader for this task. This position is characterized by the changes we are suggesting in the marked-up Guide.
This review was performed by S. Block, Radiological Assessment Branch, and P. Cota, Research and Standards Coordination Branch.
OrMrn!Signc,y1;y -
Frad S(3 roe!er.,
Frank Schroeder, Acting Director Division of Safety Technology Office of Nuclear Reactor Regulation 1
x Enclosure i
As Stated
'l Proposed Rev. 2 to Reg.
FSCHROEDER Guide 8.14 Personnel PDR JMULLIN Neutron Dosimetry JGUILBERT TSCHULTZE DST 80-133 DISTRIBUTIONS HPETTENGILL t
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Contact:
H. J. Pettengill (301) 443-5970 PROPOSED REVISION 2 TO REGULATORY GUIDE 8.14 PERSONNEL NEUTRON 00SINETEfS Do$rsfT b A.
INTRODUCTION Section 20.202, " Personnel Monitoring," of 10 CFR Part 20, " Standards for Protection Against Radiation," requires that licensees supply appropriate personnel monitoring equipment and require its use by spec.ified individuals.
This guide provides guidance acceptable to the NRC staff on the use of personnel neutron dosimeters where exposure to neutrons occurs.
B.. DISCUSSION This. guide applies to devices worn by individuals as. contrasted with hand-held or fixed area instrumentation.
It does not apply to dosimetry necessary for criticality accidents.
Criticality dosimetry. guidance is provided by American National Standard Dosimetry for Criticality Accidents, N13.3-1969.
'It is recognized that difficult problems exist in developing and estab-lishing a neutron dosimetry program.
It would be desirable for personnel u,
dosirraters to respondfproper4y over many decades of neutron energy. &r.4-foHow
. Cllinear dos _e-equ1W1ent res;icidisM.W.-
At present there aN no dosimetry-4 systemK available that exhibit these characteristiqL Furthct, only a few types of commercially available neutron dosimeters can comply.with the performance criteria listed in this guide and then.only for appifcations in which the effective dosimeter response per unit dose equivale..t does not vary appreciably with energy..For'other applications, use'of multiple dosimeter types may be necessary or advised.
It should be emphasized that! personnel neutron dosimeters are only part of the neutron protection program.
It'may.be'
- necessary to combine-the data obtained from the personnel dosimetry system and
. information from other M ulron monitoring. techniques to assess'the-neutron dose l
equivalent to workers.
This guide provides performance criteria for neutron dosimeters worn by,
. individuals.
It is applicable for neutrons with energies ranging from' thermal I
Fe t t.encil l/j k Vers 2/10-9-80 Job F i,9 to values up to 20 MeV. This guide also includts factors governing the proper
.. z u m use of dosimeters for determining the individuals' whole-body neutron dese equivalent.
Dosimetry for extremities is beyond the sccpe of this guide.
a,.
%ctor s pertainingsto.._thewearing ot _dosicetersTre, included 15-parFof-this sbndardmas a means of providingmuidance with' respect to eccept6cle per.forcance.
C.
REGULATORY FOSITION 1.
PERSONNEL NEUTRON DOSIMETRY TECHNIOUES Personnel neutron dosimeters are always required to be worn or carried whenever the neutron dose equivalent is likely to exceed 300 mrems in a quarter (10 CFR Part 20.202).
In addition, if personnel radiation monitoring is required by 620.202 be ause of total radiation exposure likely to occur, but, the neutron component of the total dose equivalent is not likely to exceed 100 mrems, then the assessment of the neutron dose by means of a personnel dosimeter is not necessary and the dose may be calculated by other means.
a.
Recommended personnel neutron dosimetry systems. When expected neutron exposures would require the use of personnel neutron dosimeters as stipulated
~
j above it is recommended that, especially for LWRs, an albedo dosimetry system 3
be used.
The NRC has reviewed the technical data such as sensitivity and the energy response threshold of other forms of cctmercially available perscnnel neutron dosimeters and finds for a variety of reasons that they would be inappro-t priate for use to monitor neutron doses of personnel in NRC licensed LWR facil-ities.
Albedo dosimeters have proven to be quite responsive to neutrons with average energies less than 100 kev which covers the averege energy for the majority of neutrons and a significant fraction of the dose attributable to workers in the NRC licensed LWR facilities (ref).
Further, albedo dosimeters have demonstrated adequate response to neutron energies of up to 10 MeV (ref).
Other major sources of neutron exposure in NRC licensed activities include Md Pode and Am-Be sources used in well logging and research activities.
Non-
- f. in hd cub 4rsku $ d' 8 albedo dosimeters such as NTA,and polycarbonates,may be used in non-LWR facilities.
b.
Calculated neutron dose.
A licenseermay substitute a calculated dose n r.
equivalent for a measu,ed dose equivalent tr the expected dose is less than l
the sensitivity of the dosimeter; or4he-neutr-on-dose-is-not-likely-=tonxceed 100=tarws.
A calculated dose equivalent may'be based upon the neutron dose 8.14-2
~
Pettengillijk Vers 2/10-9 40 Jcb F #9 equivalent rate measured by a calibrated
- rem neter survey instrument (using either the Anderson-Eraun or Hwkins design) and the occupancy time or by the use of rneasured neutron /gan.mi dose equivalent ratio.
Hcwever, the neutron /
ga.ra d::w,ratto is acceptable only :if it has been shown that tW:4utron/gms
,. a r a m. a.., u n.
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.> s e dow-retic is--victet Hy-conent-(sc.~,50*:) throughout estM area that personnel au. n w a n...
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will occupy age-eet-to-can-4mpected-to remain, constant during the ent-ire-3 I
occupancy period.
l'.cre information on determining neutron dose equivalents by neutron / gamma ratio is given in Regulatory Guide 8.4, " Direct-Reading and Indirect-Reading Pocket Dosirneters."
c.
tiegligible neutron dose equivalent.
If the neutron dose equivalent is not likely to exceed 30 millirems per calendar quarter neutron dosimeters may be omitted even if personnel dosimetry is required due to expected exposure to other forms of penetrating radiation--and the neutron dose equivalent may be assumed equal to zero.
The determination that an individual is not likely to receive a neutron dose equivalent of 30 millf rems per quarter should be based on consideration of expected occupancy times and area conitoring dosimeters or l
survey instruments sufficiently sensitive to detect this dose equivalent rate per quarter.
2.
t1EUTR0ft PER50fdEL 00SIMETRY SYSTEM PERFORMA?!CE When the use of neutron personnel dosimeters is required or advised because of potential radiation exposure conditions the dosimeters should as a minimum
(
. meet the following performance criteria:
l l
2.1 The personnel neutron dosimeter should be capable of detecting a minimum quarterly neutron dose equivalent of 100 mrems.
Thus, the lower limit of detection for the dosimetry system should be no greater than 100 mrems divided by the number of dosimetry periods per quarter. XThe quarterly lower limit of prW detection (LLD) in millirems at the 95% confidence level is defined as jy i V LLD=4.66S/if-l where ft is the number of dosimetry exchange periods in a quarter and S is the standard deviation of the normal background on the control dAeter in millirems)(
v Calibration should be performed using a similar source as used to calibrate personnel dosimeter.
8.14-3
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Vers 2/10-9 09 Job F (/9 (This definition of LLD was chosen to be consistent with the flRC position previously stated in Tables 1 and 3 of Regulatory Guide 4.8, " Environmental Technical Specifications for ituclear Power Plants." The basis for the defini-tion is given in USERDA report liASL-300, p. D-08-01.2) 2.2.The dosimetry system should be capable of determining a neutron dose equivalent up to 100 rems.
2.3 The dosicetry system shoi d be capable of detecting a neutron dose j
equivalent of 100 mrems in the presence of a dose equivalent of I rem of gamma photons of energy in excess of 100 kev.
2.4 The dosimetry system should be capable of accuracy and precision such that when two sets of ten dosimeters are exposed according to the calibration j
procedures outlined in Section C.3 to neutron dose equivalents of 100 mrems j
and-1 rem respectivelyf the standard deviation of the measured neutron dosimeter responsu should be less than 30% and 10% of the delivered dose equivalent, respectively.
1 2.5 A set of ten dosimeters exposed to an average 100 mrems from an appro-3 priate calibration source should exhibit a signal response fade of less than 20% in 30 days.
2.6 The dosimetry system should meet the requirement of Sections 2.1, 2.2 and 2.3 when subjected to the following environmental conditions following exposure using an appropriate calibration source as outlined in section C.3.
(1) Temperature extremes of -20 F and 130 F at 90% P, elative Humidity for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
(2) flormal artificial room and sunlight for 1 week.
(3) A drop to a hard surface from a height of 1.5 meter (4.9 feet).
3.
00SIMETRY SYSTEl1 CALIBRATION A calibration of the neutron personnel dosimetry system may be performed by the licensee or by someone selected by the licensee, but rer.ords describing Zitarley, John 11., Editor, llASL Procedures Manual, !!ASL-300, USERDA, revised annually.
8.14.
Pettengill/j%
Vers P/!0-9-f0 Jcb F #9 the dosimetric calibration should be naintained by the licensee.
A typical I
calibration will provide the licensee with two explicit values:
(1) the dosineter response per ren for the, calibration source, and (2) a neutron c: n.
. c.>.
4 energy calibration factor (Z)f, It is necessary that the total calibration of a particular neutron oasimetry system be performed only once; ho'aever, periodic
}
checks of,the neutron energy calibijration factor (s) (Z)' and of the constancy of the dosimetry response to a defined neutron irradiation should be performed i
by the licensee using procedures" described below.
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3.1 Heutron Eneroy Calibration Factor and Dose Eouivalent Response q'.y It may be necessary to establish a number of r.cutron energy calibration factor (s) (Z) if it is found that the spectral distribution of neutron energies varies appreciably throughout the licensed facility.
This is particularly the case 'or LWas.
The neutron energy calibration factor (s) (Z) should always be determi.. e ac~.
. w.n a sv.:.en. m..-ned,using an appro~riately calibrated neutron dose equivalent surve i
r yl.,....
p f**[C instrument.
The Z factor is defined as the ratio of the dif_fefentia]'e,r.ergy 1 o -!
respo_ns_es, for the calibration source (X) and the licensee ' facility (Y) (i.e.,
,1 p Z = X/Y).
The differential energy response values, X and Y, are both defined as the ratio of 9" to 3" neutron moderator sphere responses measured with a Anderson' Brown or flankins type neutron rem meter'&((fThe'rnethod'olcgy for deter-t h sl/l mining a 9" and 3" sphere. measurement has been previously des'cribed by Hankins 1
4 *1: s. e S"..$.
(ref).
The dose equivalent response of the, dos'imeter is determined by dividing ma-the neutron energy calibration factor (7) int'o the established dosimeter respcnse p :.. e per rem from the calibration source.
Of course, a different rem conversion r
factor is necessary at every poin,t in the licensed. faci.lity tha.t exhibits a l
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l The reccmmended catibratha-sources are-bare-CC.252,and._
different ~ ' actor.
Cf-252 moderated--by-15-cm-of-0 0.-
The fluence to rem conversion factors to be I
2 I
,..J
'3(
2 and 8.5 x 10 0 rem l
m, a used in free air for these sources are 3.4 x 10 8 rem cm e
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cm, respectively.
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- 3. 2 - Reproducible Response of Neutron Dosimeters s,.,.g
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The constancy of the dose equivalent response for dosimeters should periodically be checked.
It is assumed that no physical changes to reusable portions of a dosimeter should occur due to normal environmental or irradiation conditions.
liowever, since the response of the individual dosimeters may vary over extended periods of time it is recommenced that the licensee require certification by the commercial supplier that its dosimeters respond (readout) 8.14-5
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J Pe t.tengil l /j'.
Vers 2/10-6-80 Job f,/9
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to a defined exposure to neutron radiation with a variation of less than 10%.
i Thereafter, the response of all reuscable dosineters should be checked by licensees at least en a quarterly basis.
This may be accor.plished by exposure of the entire dosimeter device to a defined neutron irradiation.
It is highly ci recommended that licensees who use TLD albedo dosimeters purcl ase the TLD chips i
in batches which have essentially equivalent response to neutrons.
On a quarterly basis the licensee should also remeasure.the neutron energy j
calibration factor (s) (Y).
This is accomplished by a relatively simple 9" x 3" sphere measurement as discussed earlier.
If the Y value has chanced then the re-calibration of the albedo dosimetry system is simply accomplished by taking i
the ratio of the existing X value to the new Y valte and again dividing Z into the initial rem per response calibration value as performed during the initial dosimeter calibration.
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4.
MAlflTAlfill!G BODY C0tiTACT t
i Albedo neutron systems usually require close body contact at all times during usage.
Sizable errors can occur if close body contact is not maintained.
Albedo neutron dosimeters should have a means of maintaining this necessary J
close contact with the body.
D.
IfiPLEMENTATI0tl l
l This proposed Revision 2 of the guide has been released to encourage public l
participation in its development.
Except in those cases in which an applicant has prcposed an acceptable alternative nothod for complying viith specified portions of the Commission's regulations, the methods described in the~ currently active guide (Revision 1, August 1977) will continue to be used in the evalua-tion of license applications that were docketed after flovember 1, 1977.
Ti'e l
methods to be described in the active Revision 2 reflecting public comments will be used in the evaluation of all license-applications docketed after the implementation date to be specified.
The implementation date will in no case be earlier than June 1,1981.
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8.14-6~
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Pettengill/jk Vers 2/10-9-80 Jnb F V9 DRAFT VALUE/ IMPACT STATEi!Etif 1.
Tile PROPOSED ACTICII 1.1 Description of the Proposed Action
~
Section 20,202 " Personnel Monitoring," of 10 CFR Part 20, " Standards for 1
Protection Against Radiation," requires that licensees supply personnel moni-j toring equipment and require its use by specified individuals.
Some workers i
at liRC-licensed facilities roay occupy restricted areas where the potential for 1
exposure to neutrons would require the use of personnel neutron dosimeters.
The preposed action will update earlier guidance on acceptal e personnel dosimetry methods for use in assessing occupational exposure to neutrons, 1.2 fieed for the Prcposed Action a
l In August 1977, the liRC published Regulatory Guide 8.14, "Pe,rsonnel lieutron m,w
+,
Dosimeters," which indicated when personnel neutron dosimeters were required by 10 CFR.Part 20 to-be-worn-and what alternative dosimetry methodologies were acceptable in establishing the neutron dose of a worker.
Recent data obtained in conjunction with two research contracts
- funded by the fiRC show that (1) liTA film is not a reliable dosimeter for use in assessing neutron doses when a large proportion of the neutron dose is from neutrons with energies less than 0.7 IMV, which is considered the threshold energ.' of film in
?,., u
.n a oc and (2) the use of a neutron / gamma ratio does not always enable acc urate esti-mation of the neutron Aose-unless it can be e.stablis.hed by routine and periodic mn. w a.
a n,:o... m m s.e, a n r.h e.-
surveys that the ratic remains constant.
This research also indicated that 3,3 -
other non albedo dosimeters generally locked the sensitivity (loi.er limit of 7;-
l detection) to measure neutron doses typically received by worker at LWRs.
The - o,m u,
scope of these research contracts was to measure and characterize the neutron spectra in the containment of pressurized water reactors (PWRs) and to test the w s..
l response of commercial personnel dosimeters to the neutron spectr
.u -
reactor containment structures while at power and to evaluate the response of-numerous survey instruments where appropriate.
.Z'"
.0 wing to many causal. factors such as humidity, fading, lack of sensitivity, '"[
and the general inability of flTA film to respond to neutrons with energies less
/. -
c..y 3
^Hensseiner Polytecr.nic Institute Research Project flo. 5-24675 and Department of Energy Contract EY-76-C-06-1830 with Battelle Pacific Northwest Laboratory.
8.-14-7
b Petter.qi l l/ ik Vers 2/10-9-d0 Jcb f #9 than 0,711eV, tiTA film has been demcnstrated to be a very poor dosimeter for use at power reactors.
Like. rise ci er non-albedo dosimeters (polycarbonates and Cr-39) generally lacked sensivity to detect doses below hundreds of arems, Data ccmpiled in the above research programs showed that flTA film did not respond at all or measured only a very small fraction of the neutron dese.
Also, an aslesb.elit of the neutron / gamma ratio throughout a power reactor containment by one researcher (Rensselaer Polytechnic Institute) shcwed that the ratio may i
vary significantly depending on the location in the reactor containment structure.
and.the energy response function.of the type 'of. neutron, survey ' instr.ument used.
Active Regulatory Guide 8.14 (Revision 1, August 1977), although it cau-tions the licensee of the limitations of tiTA film, does not advise the licensee that NTA film is not acceptable for nutron personnel dosimetry at power reac-tors.
The data compiled in the two f1RC research programs on this subject show that technical advances in albedo dosimeters make them a better alternative to NTA and polycarbonate film, as a neutron personnel dosimeter for use at nuclear r,. e - m e s, s em e m s e e.e vu.;... n.. a:-
m,aa s,.n au n.. ::m >.
power reactors.
Also, the current auide allows the use of neutron / gamna ratics as an acceptable method of calculating the neutron dose in those cases in which a dosimeter has demonstrated lack of sensitivity or the neutron dose is not expected to exceed 300 millirems per quarter but personnel dosircetry is required by S 20.202 for other forms of radiation, liowever, the neutron gamma / ratio
- variE9 widely through the containment structure of a nuclear power plant and 'a "
4 irr-ordtr to obtain accurate estimation of a neutron dose received, ev.idence em.% m l
that'the ratio remains-constant should be er-tablished by routine and periodic surveys of areas for which this ratio is to be applied. ' The-NRC-staff-believes 7, 3 w,
it_is therefore appropriate-to revise Regulatory Guide-B.14 to reflect this-l Sw recently acquired information on neutron dosimatry.
- .a i
1.3 Value/ Impact of the Proposed Ac'. ion l
1.3.1 NRC Operations The value in revising Regulatory Guide 8.14 is that it would provide the licenseeandtheNRCinspectorwith"stateofthetechnology"neutrondosimetrh,
~
which has changed somewhat since the development of the existing guide.
The actual development of the revised Regulatory Guide 8.14 will require few addi-
!~
tional resources of either man-hours'or funding.
Two NRC contracts on analysis of neutron spectra and various dosimeter responses to. moderated fission neutrons
,8.14-8
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2 Pettengill/jk Vers 2/10-9-60 Job f a in power reactors have been completed, and final reports will likely be completed this year.
The data compiled frcn these contracts provide the bases for the proposed changes in Regulatory Guide 8.14.
1.3.2 Other Government Agencies flot applicable.
i 1.3.3 Industry There should be little impact on industry.
The revision of Regulatory Guide 8.14 will require few. additional expenditures of time or resources since the revised guide is intended to reflect tSe current " state of technology" in personnel neutron dosimetry.
The only significant economic irrpact that could f
result would be the loss of revenue by a few dosimetry processors that now provide flTA film badge service to nuclear power reactor licensees cince the major purpose of revising Regulatory Guide 8.14 is to advise power reactor
{
ifcensees that flTA film should not be used for neutron dosinetry.
Power reactor licensees who calculate the neutron dose by the neutron /
o s.w I
Gamma ratio method will now be required to demonstrate that the neutron / gamma 3
o ratio is constant within 50' in those areas of the reactor contair.. ment where 3
it is intended to use the ratio to calculate the neutron dose.
A-change-to
-the stay-time method day rq0iFe Che purchase ofTdd'i'Cionariieutron survey l
instruments.
liowever-Fthe-proposed-guida-.-states that_the_Ose_of-the-neutron /
j gamma ratio.nethod may-s-ti-1-1-be-justi fitf<i~fe'r' ruse as long as-the-1icensee can
~-
1 i
demenstr. ate.that.the ratio.is virtually constant-throughout-areas-normally p,.a se im< w-r -
-a w !wa s
-t %.' a r vta.u t-cccupied by workers.
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A recent survey of some NRC licensees by the (1RC Office of Inspection and Enforcement provides data indicating that only one out of fif teen PWRs surveyed used flTA film to assess neutron dose.
Also, only one PWR used the neutron /
gamma ratio method instead of the stay-time method to assess neutron dose for l
containment entry while'at power.
1.3.4 Workers l'
There would be no expected detrimental impact to workers.
The value would i
be that a worker would know that " state-of-the-technology" dosimetry techniques l
are being examined to ensure that'the best nethods are being used to assess his i
or her exposure to neutrons. 'By ensuring that'the best dosimetry techniques i
8.14 l
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are used, the integrated risk to a worker from exposure to radiation ccn be better evaluated.
Particular problems with NTA film include limited son'itivity, i
j fading due to humidity, and ener0y dependence; these factors are often inter-preted to mean a zero dose even though use of portable survey instruments has established that neutrons exist in the working area.
Sinilarly, the improper j
use of the neutron / gamma ratio method may result in a poor evaluation of the worker's neutron dose equivalent, j
If the worker's neutron exposure is determined using more sensitive and j
accurate dosimetry techniques, it may result in the limitation (i.e., reduction) j of the exposure to other forms of radiation.
To this extent, the risk to an individual worker could possibly be reduced.
However, by using dosimeters that i
j are more sensitive than flTA and polycarbonate film, one might also witness an l
apparent increase in the individual or collective dose because neutron exposure that had previously been assumed to be zero could now be assessed.
However the potential impact on the collective dose would not be great since neutron i
exposures at nuclear power reactors constitute a small fraction of the total U t.? L j
collective dose.
Also, only a limited number' of workers,who may be required l
to enter contcinment during power operation,are exposed to neutrons.
The. importance of very accurately assessing any exposure to intermediate j.
or fast n'eutrons is highlighted by the recent controversy over the need to adjust j
the quality factor used to determine the neutron dose equivalent.
Dr. flarold i
j Rossi has proposed on the basis of a dual-action theory-(dose squared respons'e i
of low LET radiation) that the quality factor for neutrons needs to be increased s
s r
an order o' magnitude.
If Rossi's contentions are proven corrcct, low levels f
rr-x s
of neutron exposure to the limited number of workcrs who routinely enter the N
N
\\
s containment structure of FWL while they are at power may become' the limiting exposure circumstances for these workers.
1.3.5 Public flot applicable.
1.4 Decision on the Proposed Action' It -is' recommended that a revision of Regulatory Guide 8.14 be undertaken in order to ensure titat nuclear power plant licensees use personnel neutron dosimetry methods that are both accurate and of appropriate sensitivity to
- evaluate' neutron exposures experienced in working areas.
8.14-10 L
Pettcniil'/jk
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Vers 2/.t0 9 ;0 J ob F
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2.
TECHNICAL APPROACH Since the intent is to revise an existing regulatory guide in crder to incorporate updated technical information on acceptable personaal neutron dosincters and acceptable methods for calculating neutron doses when-the-uso-of-a. personnel dosimeter-ic-not-warralit6% na alternative technical approaches have been identified.
I 3.
PROCEDURAL APPROACH The only procedural opproach considered is the revision of Regulatory Guide 8.14, " Personnel Neutron Dosimeters."
4.
STATUTORY CONSIDERATIONS 4.1 NRC Authority The regulatory guide does not have the force of law, however, it is intended as an aid and describes methods that are acceptable to the NRC staff and that a licensee may adopt in order to be in compliance with a regulation that has the forcr of law.
4.2 !!eed for NEPA Statement The revision of Regulatory Guide 8.14 has no environmental impact; therefore no NEPA statement is required.
5.
RELATIONSHIP TO OTHER EXISTING OR PROPOSED REGULATIONS OR POLICIES lio known conflict with any existing regulation or other government policy exists.
6.
SU:"!ARY AND CONCLUSIONS Some data obtained from the two NRC research contracts have shown that theenergyandconcomitantdosedistributiono/x.nn..u..,e6 fission neutrons within PWR uo
~
containments is such that NTA and polycarbonate film is of little value'as a g
personnel dosimeter.
There is little neutron exposure associated with most boil-iny % '.r-watec_ reactors compared with PWRs because of their design 'dif ferences and because there is no entry to the drywell area during power operation of BWRs inerted with nitrogen..It-is known that NTA film does not respond to neutrons with energies less than about 0.7 MeV and further that most'of the
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neutron fluence.In a typical n!R contain. ment during power operation is,.less t
i than 0.7 f:eV.
It is also known that flTA fila is relatively insensitive to doses of less than 50 millirems per exposure and is quite susceptible to fading caused byhumidityunlessproperlypackagc7Am,,in.....s.In this regard, one often finds that d
l temperature and humidity are normally quite high in the containment of P',lRs and that most contailm.cnt entries to make routine inspections result in neutron doses of less than 30 mrems.
Only personne,l dosirneters with proven sensitivity i
4 to low-and intermediate-energy neutrons (iE S,, albedo dosimeters) should be used at nuc1 car pcuer plants.
EnrJw-dwe-siturtimTs., / alternative r.:ethods of calculating neutron dase rnay be acceptable in lieu of a personnel desirneter.
l Acceptable taethods include the neutron /guna dose ratio and stay-time.
- lichever, 4
It sintb the neutron /ga=aa ratio has-been shown to vary widely in work areas of i
PWR containments, it should be used with discretion.
'~
In order to ensure that workers are provided with appropriate personnel l
neutron dosimetry, the staff has determined that Regulatory Guide 8.14 should
.a be revised to reflect the following:
(1) t1TA filra is not an acceptable personnel l
i neutron dositaeter for use at nucicar power plants, (2) other non-albedo dosimeters
. ' ' ".... L,'
j should be u;cd only when it can be demonstrated they have demonstrated sensitivity to the neutron environraent and doses typically received by workers, and (3) the l
use of the neutron / gamma ratio as an alternative method to calculate neutron dose is acceptable, especially for nuclear power plants, only when it is demon-l strated that the ratio remains virtually constant.in all occupied work arcas.
a l
t 8.14-12 L
-