ML20198Q110

Working Paper Entitled, Demonstrating Compliance W/Radiological Criteria for Decommissioning Section C.4: Regulatory Position:Alara Analyses, for Future Regulatory Guide

ML20198Q110
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Issue date:	01/08/1998
From:	NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
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intphtuliconf.l!nl gov /radcri'modc4.html http:/1cchconf.llnl gov /raderi'modc4.html WORKING PAPER REGU.LATORY GUIDE:

DEMONSTRATING COMPLIANCE WITH THE RADIOi.OGICAL CRITERIA FOR DECOMMISSIONING SECTION C.4: REGULATORY POSITION:

ALARA ANALYSES Office of Nuclear Regulatory Research U. S. Nuclear llegulatory Commission DISCLA!MER This working paper is being developed for a future NRC Regulatory Guide, "1.Nmonstrating Compliance with the Radiological Criteria for Decommissioning." It is a working drall only and is subject to extensive change. Its purpose is to obtain comments from NRC staff and others, it has received only limited NRC staff review and no NRC management approval.

4.0 Analyses to demons.imte AI. ARA. net public or environmental hann. not technically achievable. and prohibitively exnensive in order to tenninate a license, a licensee must demonstrate that a dose limit has been met and, in addition, must demonstrate that it is not feasible to further reduce the levels of residual radioactivity to levels below those necessary to meet the dose limit. This section of the guide describes an acceptable methodology to detennine when it is feasible to further reduce the levels of residual radioactivity beyond those necessary to meet the dose limit.

Type I licensees (as defined in guide Section B. " Discussion") need not perform the analyses described m.

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ittpl/tecikonf.llnl gov /radcri'modc4.html hup://techconf.llnl gov /radcri!n.9dc4.html in this section because Ty pe I licensees have essentially no potential for signincant residuali a.ivity l*

c the site. Therefore, by d efinitbn, they meet the requirement without an explicit analysis. l..

tion, I

explicit analyses da not have to be done for areas where residual radioactivity is indistmguishable from background, as described in guide Section C.2. If residual radioactivity cannot be detected, it may be assumed that it has been reduced to levels that are as low as is reasonably achievable.

Several characteristics are desirable in a method to determine iflevels of residual radioactivity are ALARA:

1. The method should be simple.

2.The method should not be biased.

3. The method should use the same dose modeling that is used to relate concentrations to dose.

4. The method should be usable as a remediation plam.ing tool.

5.The demonstration that the ALARA criterion has been met should use the results from the final site survey.

The method should be simple because the effort needed for very sophisticW models cannot be justified. The primary benent of a remediation action, radiation doses avertea in the future, is not really kno vable. It is not 30ssible to know the future land uses or number of people that will actually occupy a site. For example, t ie residential scenario assumes people will build a house on the site, use a well for their drinking water, and eat crops grown on the site. But will a house really be built there or will the area be an unoccupied field? If t acre is a house, how many occupants will it have? Will a well be drilled at a location that has residual radioactivity? Will the site residents really grow their own food on the site? The answers to these questions are not knowable. Thus, future collective dose cannot be known with precision regardless of how much effort is made. Because of this inherent limitation on our ability to precisely determine the future collective dose at a particular site, it is not uppropriate to perform a complicated and expensive analysis when a simi,lc analysis will suffice.

The method should not be biased. Dose limits typically define an adequate level of protection. When de:rmining compliance with a dose limit that provides adequate protection, a measurement with a onwrvative bias is ollen sought. This assures that compliance with the limit established to provide auq%te protection has been met. An ALARA analysis is an optimization technique that seeks the proper balance between costs and benefits below the dose limit. A balance requires that each factor be detemiined.ath as little bias as possible. If the analysis were intentionally biased in either direction, it would caua a misallocation of resources. A misallocation of resources would deprive society of the benef ts from other uses of the resources.

Gere are different ways that a remediation action can affect the future well being of society. A remediation action can avert future dose, which is a benefit. 7 he remediation action can also cost money, which can be a detriment. According to modern research in economic theory, loss of the effective use of this capital will deprive future generations of the return on the investment of this money, which is a detriment to society. Thus, if a great deal of money is spent for a cleanup that would have a very small future benefit, it would be detrimental to future generations. The OMB guidance to Federal agencies that implements President Clinton's Executive Order 12866 (Reference 1) incorporates this approach in analyzing the potential benefits of federal regulations (Reference 2).

Tbc choice of the dose model used involves a trade-off between the objectives of simplicity and achieving a lack of bias. The objective to reduce bias is not met when we use the same dose models to demonstrate compliance with the dose limit and the ALARA criterion. The critical group used in the dose models was intentionally selected to be a group with characteristics defined to maximize dose, not to give a best estimate of the most likely value of dose to typical site occupants. Thus, the calculated benefits (averted doses) due to reducing levels of residual radioactivity would not be likely to be fully realized. On the other hand, dose models are difficult to develop and to use. Therefore it may be appropriate to compromise on the objective oflack of bias in order to avoid unnecessary complexity, i

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http1/tecticonf.llnl gov!radcri/modc4.html hupv/techeonf.llntgov/raderi' mod:4.html appropriate to compromise on toe objective oflack of bias in order to avoid unnecessary complexity.

The method should be usable as a re.nediation planning tool. In other words, before starting a remediation action, the user should be able to determine what concentration of residual radioactivity would require a remediation action to meet the ALARA criteria. It is inefficient if the user can not te I whether the at:a would pass the ALARA test until after the remediation were done.

The method should allow use of the ret Its from the final site survey to identify locations whose concentrations are high enougl that a tvinedlation actions should have been taken. It is inefficient to require a additional set of meas rements to demonstrate remediation actions were taken wherever appropriate to meet the ALARA u mia if the et of measurements used to demonstrate compliance with the dose limit can be used for both 4.1 ALARA analyses Certain sections of Subpart E of Part 20 require a demonstration that residual radioac'.ivity has been reduced to a level that is as low as is reasonably achievable (ALARA) (10 CFR 20.1402,20.1403(a),

20.1403(e), and 20.1404(a)(3)). A simplified method for demon:frating compliance with the ALARA requiremer.t is described below, Licensees may use more realistic or site-specific analyses if more appropriate for their specific situation. Guidance on more realistic and complex modeling is contained in guide Sections C.4.1.7 and C.4.1.8.

The simplified method presented here estimates the concentration above which a remediation action would be cost effective. The remediation action being evaluated is cost efTective at all locations where the desired beneficial effects (" benefits") due to the remediation action are greater than the undesirable etTects or " costs" of the action.

The method is applied during remediation planning prior to the start of remediation but after some or all of the characterization work is done. The method is used to determine only whether and where particular remediation actiot's should be taken to meet the ALARA requirement. Thus, the ALARA method determines concentrations at which remediation actions should be taken. The method does not establish concentration limits that cannot be exceeded. For example, the ALARA method might indicate that the 2

fioor of a building should be washed anywhere the concentration exceeds I pCi/cm. If the actual concentration prior to washing were 10 pCi/cm2 and 9 pCi/cm2 after washing, the ALARA requirement has been met because washing was performed at locations having an activity exceeding 1 pCi/cm2.

Meeting the ALARA requirement is done by performing the remediation action at certain locations, not by getting below a specified concentration after the action.

In order to compare benefits and costs of a remediation action, it is necessary to use a comparable unit of measure. The unit of measure used here is the dollar. Thus, all benefits and costs are given a monetary value, llenefits and costs are calculated as described in Sectiors C.4.1.1 and C.4.1.2 below. The calculation determines the concentration at whiwh the benefits of a remediation action being analyzed equal the costs of the action. The remediation action should be taken at all locations with higher concentrmions to meet the ALARA criterion. Locations with lower concentrations meet the ALARA criterion without the need for the remediation action.

Note that if the licensee plans to perform a remediation action, there is no need to analyze whether the action is necessary just to meet the ALARA rec uirement. The analysis described in this section is used only to justify noj taking a remediation action. 7or example, if a licensee plans to wash room surfaces (either to meet the dose limit or as a good practice procedure) there is no need to analyze whether the remediation action of washing is necessary to meet the ALARA requirement.

In the method describcd below, both the costs and benefits are calculated on a per-unit-area basis. The

' advantage of this approach is that the licensee can use the method as a planning tool before determining the size of the area to which the remediation action would be applied and before remediation has begun.

If the licensee wants to evaluate a particular size area, this method can still be used; it is only necessary to multiply each term (benefits and costs) by the size of the area.

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http://tecficonf.sint Eov/radcri/modc4.html http://techconf.llnl gov /raderi'modc4.html 4.1.1 DJgulation of benents in the simplest form of the analysis, the only benent estimated from a redu: tion in the level of residual radioactivity is the monetary value of the reduction in collective dose to future occupants of the site. For-buildings, the future collective dose from residual radio'ictivity is based on the building occu pancy scenario. For land, the dose is basel on the resident farmer scenario. Additional benents, such as those from reducing levels so that u cite cauld have unrestricted release instead of restricted release, are discussed in C 4.1.7, which enls with more complex analyses.

The benefit from averted dose, BAD, due to a fractional reduction F in residual radioactivity concentration is calculated per t. nit area by determining the future collective dose and multiplying it by a factor to convert the dose to monetary value. The equation below may be used. (The derivation of this equation is given in the appendix at the end of this section.)

C

1. U'W - 1 B, = $2000 x Po x 0.025 x F x x

(1)

DCOL (r t A)e"'"

r 2

. where B n = the benefit due to averted dose for a remediation action per unit area in $/m 3

$2000 = the value in dollars of a person-rem averted (from Reference 3) 2 Po = the population density of people likely to occupy the site afler license termination in people /m,

0.025 = the annual dose to an average member of the critical group from residual radioactivity at the DCGLw concentration distributed unifonnly throughout a survey unit in rems /yr.

F = the fraction of the residual radioactivity removed by the remediation action.

C = the concentration of residual radioactivity in units of activity per unit area for buildings or activity per unit volume for soils.

DCGLw = The derived concentration guideline equivalent to the average concentration of residual radioactivity that would give a dose of 25 mrem /yr to the average member of the critical group, in the same units as C.

r = the monetary discount rate in units of yrl.

= the radiological decay constant for the radionuclide in units of yrl N = the number of years over which the collective dose will be calculated.

The regulation (10 CFR 20.1403(e)) states, " residual radioactivity at the site has been reduced so that if the institutional controls were no longer in effect, there is reasonable assurance that the TEDE from

. residual radioactivity distinguishable from background to the average member of the critical group is as low as is reasonably achievable..." Therefore, the licensee should use the same DCGLw that will be -

used to demonstrate compliance with the dose limit.

The 30pulation density PD should be based on the most likely or expected use of the site. Thus, for builtings, the licensee snould estimate PD for the expected or most likely use of the building for the

' forseea ale future. For soil, the expected land use should be for the resident farmer in order to be consistent with the dose scenario. Thus, the PD should be based on values for farming. While highter densities could occur, there should not be used unless the dose scenario is also changed. in gener, this is not recommended.

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AD or each radionuclide is calculated individually If more than one radionuclide is present, the benefit B f

and summed to calculate the total averted dose benefit from a remediation action.

An acceptable value for a reduction in the collective dose is $2000 per person-rem averted, discoimted for dose averted in the future. (See Q 4.3.3 of Reference 3) According to References 2 and 3, for doses averted within the first 100 years, a discount rate of 7 percent should be used. For doses averted beyond 100 years, a 3 percent discount rate should be used.

The factor at the far right of the equation, which includes the exponential terms, accounts for both the present worth of the monetary value and radiological decay.

4.1.2 Calculation of costs The costs to be considered in evaluating a remediation action include: (1) the monetary cost of performing the remediation action being evaluated, (2) the monetary cost of transporting and disposing of the waste generated by the action,(3) the monetary cost of workplace accidents that occur due to the remediation action, (4) the monetary cost of traffic fatalities resulting from transporting the waste generated by the action, (5) the monetary cost of doses received by workers performing the remediation

- action, and (6) dose to the public due to excavation, transport, and disposal of the waste.

The total cost per unit area, Cug, which is balanced against the benefits per unit area, is composed of several components:

Cm = C, t Cup tC tC t C,% tC e

y im (2) where Cg = the monetary cost per unit area remediated of the remediation action Cwo = the monetary cost per unit area remediated for transport and disposal of the waste generated by the action C cc = the monetary cost per unit area remediated of worker accidents during the remediation action A

CTF = the monetary cost per unit area remediated of traffic fatalities during transporting of the waste Cwoos, = the monetary cost per unit area remediated of dose received by workers performing the remediation action and transporting waste to the disposal facility Cpoose = dose to the public due to excavation, transport, and disposal of the waste

'All of the costs described below do not necessarily have to be calculated. For example, if one or two of the costs can be shown to be in excess of the benefit, the remediation action being considered has been shown to be unnecessary without calculating the other costs.

To calculate the monetary cost of a remediation action, Cg, the cost per unit area may be estimated based on site-specific conditions. Use of a generic estimate of 1.62 person-hours to excavate, monitor, 3

l _

package, and handle 1 m of soilis acceptable (Reference 3, Addendum 1)

- The cost of wasu transport and disposal, Cwo, should be evaluated on a per unit area basis with units of 2

$/m according to the following equation:

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Gw*Vs

• Ur (3) 3 2 Where V = the volume of waste produced per unit area remediated in units of m /m,

A 3

Cy = the cost of waste disposal, including transportation cost, in units of $/m.

2 The cost of non radiological workplace accidents, C cc, in units of $/m should be evaluated using to A

the equation below:

Ce = $3,000,000 x F, x T3 (4) where $3,000,000 = the monetary value of a fatality equivalent to $2000/ person-rem (from NUREG 1530,pages Il-12).

Fw = workplace fatality rate in fatalities / hour worked.

2 T = the worker time required for remediation per unit area in units of worker-hours /m,

A 2

The cost of traffic fatalities incurred during the shipment of waste, CTF, in units of $/m should be calculated according to the equation below:

FxD y

r C. = $3,000,000 x V x (5) rr 3

ym,7 3 2 where V = the voiame of waste produced per unit area remediated in units of m /m,

A F = the truck fatality rate per kilometer traveled in units of fatalities /km.

T D = the distance traveled by truck in km.

T 3

VsillP,T = the volume of a truck shipment in m.

The cost of the remediation worl{er dose, Cwoose, in $/m can be calculated as shown in the following 2

equation:

C

, =. $2000 x -D, x T (6) where Da = the total etTective dose equivalent rate to remediation workers in units of rems /hr.

2 T = the time worked (site labor) to remediate a unit area in units of person-hr/m,

The dose to the worker is the sum of the intemal dose equivalent and the extemal dose equivalent. The

. intemal dose equivalent D, int for the removal of soil may be estimated from the following equation:

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Dp = C x DCF3 x BR x 7;,,, x V x DL x RF (7)

The cost of worker dose usually should not be discounted because the dose is all incurred close to the time oflicense termination.

For performing these calculations, acceptable values for some of the parameters are shown in Table 4.1.

Table 4.1. Acceptable parameter vahics for use in ALARA analyses.

Parameter-Value Reference and comments Workplace accident 4.2 x 10-8/hr NUREG 1496, Volume 2, Appendix B, Table A.1.

fatality rate Fransportation fatal trucks: 3.8 x NUREG-1496, Volume 2, Appendix B Table A.1.

accident rate 10-8/km

$/ person rem i$2000 NUlWG/BR-0058 monetary discount rate buildings: 0.07/yr NUREG/BR-0058 r

soil: 0.03/yr Number 01')' cars of buildings: 70 yr NUREG-1496, Volume 2, Appendix B, Table A.I.

exposure, N Shorter values for buildings may be used if the useful soil: 1000 yr life of the building is shorter, population density, Po building: 0.09 NUREG-1496, Volume 2, Appendix, Table A.1. See 2

this reference for values for special situations.

person /m land: 0.0004 person /m2 waste shipment volume, truck: 13.6 NUREG-1496, Volume 2, Appendix B, Table A.1.

Vsitir 3

m / shipment l

4.1.3 Residual radioactivity levels that are ALARA The residual radioactivity level that is ALARA is the concentration C at which the benefit from removal equals the cost or removal. Using equations 1 and 2, the ratio of the concentration C to the DCGLw can be determined (derivation shown in appendix):

C C

• (r t 1) e ('

• A) #

m

@)

DCM,

$2000 x Po x 0.025 x F eVW-i Since Po, N, and r are constants that have generic values for all locations on the site, the licensee needs l

only to determine the total cost per unit area, CUA, and the effectiveness F for a specific remediation action. If the concentration at a location exceeds C, it will be cost effective to remediate the location by a method whose total cost per unit area is Cug. Note that the concentration C that is ALAP.A can be higher or lower (more or less stringent) than the DCGLw, which equates to 25 mrem to the average member of the critical group.-

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- http;//techeonf.lini gov /radcri'modc4.html If the remediation method is applied, there is no need to compare the final status survey results to C, if the remediation action is not applied, the licensee should demonstrate in the final radiation status report

=<

that all concentrations in the survey unit are less than C.

4.1.4 Example calculations Example 1: Washing building surfaces Consider a building with cesium-137 residual radioactivity ( = 0.023/yr). The remediation action to be 2

considered is washing of surfaces. The licensee estimates that this will cost $1/m and will remove half (F = 0.5) of the residual radioactivity. For buildings, generic parameters are: Po = 0.09 person /m2, r =

0.07/yr, and N = 70 years. Using these values in Equation 8'gives:

C

$1/m2 (0.07 t 0.023) etom. am x M

DCOL,

$2000 x 0.5 x 0.025 x 0,09

,(om. amm. 3 C

= 0.041 (10) gggg This result means that to meet the ALARA requirement any spot with a concentration exceeding about 4% of the DCGLw must be washed. Note that this is much more stringent than the dose limit. This calculation shows that washing building surfaces is usually necessary to meet the ALARA requirement.

If the surfaces will be washed, there is no need for the licensee to perform the ALARA evaluation or to submit the evaluation to the NRC. If the licensee decided not to wash the building surfaces, the licensee could submit this evaluation and demonstrate that all surfaces have a concentration below 4% of the DCGLw. This would be a much more stringent survey than a survey designed to demonstrate compliance with the dose limit.

Example 2: Scabbling concrete in a building This is the same example as above except that scabbling to a depth of 1/8 inch. The licensee estimates 2

the total cost of the scabbling will be $50/m and estimates that it will remove all the residual radioactivity so that F = 1. Using these values in Equation 8 gives:

x (0.07 t 0.023) e @W

• GA E C'

$50/m2

@)

ECOL,

$2000 x 1 x 0.025 x 0.09

,om.onn)m _ j C

" 0'97 N)

DCGLw The licensee could decide to scabble some or all surfaces depending on the concentrations present. For areas not scabbled, the licensee could provide this analysis and demonstrate that all concentrations in the survey unit are less than 0.97 DCGLw.

Example 3: Removing surface soll Soil is found to contain radium-226 ( = 0.000247/yr) residual radioactivity to a depth of 15 cm. 'lhe 2

'. licensee estimates that the cost of removing the soil (F = 1) will be $100/m. For soil, the generic 8 cf 14.-

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j parameters are: P6 = 0.0004 person /m2, r = 0.03/yr; ahd N = 1000 yr. Using these values in Equation 8 ;

j

'gives::

j f (0.03 t 0.000247),em iomaam imo C

$100/m2 g

' G3) -

DC%_ : $2000 x21 x 0.025 x 0.0004_

,com. omaan;icoo. )

I C

151<

g4)

=

.I Thus, meeting the dose limit would be limiting by a considerable margin. It would rarely be necessary to 3

ship soil to a waste disposal facility to meet the ALARA requirement. The licensee could use this '

i t

evaluation tojustify not removing soil.-

a The advantage of the approach shown in these examples is that it allows the user to know the ALARA

' target concentration, independent of area, prior to starting remediation and prior to planning the final 1

1 status survey. Thus, it is a powerful plannmg tool letting the user determine which remediation actions will be needed to meet the ALARA requirement.

4.1.6 When mathematical analyses are not aggessarY In certain circumstances, the re'sults of an ALARA analysis are known on a generic basis. In these situations, an analysis is not necessary. For residual radioactiviity in soil at sites that will have unrestricted release, generic analyses show that removal of sioil is never cost effective. Therefore

' removal of soil does not have to be evalu ited for unrestricted release. For buildings, washing is almost

'always cost effective, except when very small quantitiies of radioactivity were handled. Thus, washing of should normally be performed and the analysis would not have to be done for washing.

4.1.7 More complex analyses

_ The purpose of the method described above is to present a metiiod with minimal analysis cost that is i

dequate for most situations, llowever, other factors as described below should be included if the site will be released under restricted conditions. In particular, additional costs that would not be incurred are i

an additional benefit.-In other cases as described in items 2 to 7 below, licensees may prefer to use more realistic or site-specific methods. Some factors that may be included in 'more complex analyses are given below:

1. Restricted release:

z With restricted release, there are several factors that should be evaluated that are not -

proportional to the size of the area being evaluated. The additional benefits that should be -

evaluated in the ALARA analysis if a remediation action would allow a site to have

! unrestricted release instead of restricted release are the monetary value from not having to

. provide restrictions land financial assurance, Bs (see guide section C.3.2), benefit of a L higher property _ value; Bpy, and the benefit of requiring less rbsources for evaluation by the -

NRC of the licensee's applicatics hr restricted release submitted in the decommissioning

plan,B_ NRC. The inc_reased propeity value can be estimated by consulting a real estate agent -

that' specializes in the sales of" brown field" properties.

s 5

These costs are independent of the area being evaluated. However, in order to consider these benefits, it is necessary to estimate the area A that will be affected because Equation 8 uses

' costs per unit area. This will be an iterative process because the area' cannot be precisely y

Ldefined until the concentration requiring the remediation action is known, but the -

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__ http://techconf.lini. gov /radcri/modc4.html d concentration cannot be calculated until the size of the area exceeding this concentration is t

determined. An iterative approach can be used 3 determine both the concentration and the

- area where is concentration is exceeded._-When the area A is estimated, it is possible to '

? divide the monetary values of the additional benefits by A to calculate a total additional :

benefit per unit area, BUA. Dus, the total additional benefit per unit area Bur (in addition to the benefit of averted dese) per unit area isi "B

tBy+Bm.

n

._Bm=

.(15)-

-A

.T Groundwater:

f 2

i

If there is extensive groundwater contamination, it may be necessary to calculate the --

collective dese from consumption of the groundwater, i

3. Ponulation density:

The current population density for the area surrounding the site may be substituted for the

' default population density for land, Po, in Equation 8,

4. Costs of delay in usinn site:

1 The fair market rental value for the site during the time that remediation work would be

- performed may be added to the costs in Equation 8.

- 5. Unlaue site conditions:

'If unique site conditions would add extra costs, those costs may be included.

6. Non-auantifiable imoacts There may be occasions where it is very difficult or impossible to place a monetary value on an impact. A best effort should be made to assign a monetary value to the impact because otherwise there may be no way to compare benefits to costs.

7. Environmental denradatiggi A remediation action may dama'ge an ecologickl valuable area or cause some other adverse environmental impact. These impacts should be included as costs of the remediation action.

~

4.1.8 Alternate method Another acceptable method to demonstrate c6mpliance with the ALARA requirement is contained in Draft DOE Standard, " Applying the ALARA Process for Radiation Protection of the Public and.

Environmental Compliance with 10 CFR part 834 and Doe 5400.5 ALARA Program Requirements,"

April,1997,)

,1

~

i 4.2 Determination of" net oublic or environmental harm" ~

Certain sections of Subpart E of Part 20 require a demonstration that furiher remediation would cause net public or environmental harm (10 CFR 20.1403(a), or 20.1403(e)(2)(i)). The calculation to J demonstrate net public or environmental harm is a special case of the general ALARA calculation =

described above that co npares the benefits in dose reduction to the cost of doses, injuries, and fatalities L

iincurred. The calculation is done without considering the monetary costs of performing further -

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remediation C or the costs of waste disposal Cwo. Thus, if the benefit B is less than the sum of the R

costs of workplace accidents C cc, the costs of transportation fatalities CTF, the costs of remediation A

worker dose Co, and the costs of any environmental degradation CED, then there is net public or environmental harm. Thus, there is net environmental harm if:

tCu+Cp+Cm (16)

Net pubhc cr endronmental harm tf Ba<Ca 4.3 Demenstration of"not technically achievable" One section of Subp3rt E of Part 20 contains a requirement to demonstration that further reductions in residual radioactivity are not technically achievable (10 CFR 20.1403(c)(2)(i)). Remediation of residual radioactivity is almost always technically achievable even if not economically feasible. This provision allows for special cases that may not be foreseeable. Thus, specific guidance on this provision cannot be provided. Instead, evaluations oflicensee submittals will be done on a case-by-case basis.

4.4 Demonstration of" prohibitively exnensive" One section of Subpart E of Part 20 contains a requirement to demonstration that further reductions in residual radioactivity would be prohibitively expensive (10 CFR 20.1403(e)(2)). This section discusses how to evaluate whether further reductions would be prohibitively expensive.

There are two ways to demo.atrate that further reductions in residual radioactivity are prohibitively

- ex xnsive. The first way is by doin ; an analysis like the ALARA analysis described abave, but usmg a va ue of $20,000 per person-rem w 1en calculating the value of the averted dose. This value reflects the Commission's statement in the final rule on radiological criteria for license termination, which stated that a remediation would be prohibitively expensive if the cost to avert dose were about an order of magnitude more expensive than the cost recommended by the Commission for an ALARA analysis (Reference 3). The second way is by demonstrating that the cleanup cost would threaten the financial viability of the company, To demonstrate this, the licensee should provide a statement by a reputable financial or investment institution (bank, accounting firm, investment firm) that the costs of additional remediation would threaten the financial viability of the licensee.

4.5 Information to be submitted in the decommissionine olan or license termination nian The decommissioning plan or license termination plan should describe the remediation actions that will be taken. Remediation actions that might normally be taken for ALARA but which will not be taken should be justified. Those justifications should include the concentration above which the actions not taken would bejustified.

4.6 Information to be submitted in the final radiation status renort The final radiation status report should describe the remediation actions taken. It should also tell if any survey units contained areas with concentrations above which a remediation action not taken would be justified.

APPENDIX Derivation of Equation 8 The ALARA analysis compares the monetary value of the desirable effects (benefits) of a remediation

. action, for example, the monetary benefit of averted dose, with the monetary value of the undesirable effects, for example, the costs of waste disposal. If the benefits of a remediation action would exceed the costs, then the remediation action should be taken to meet the ALARA requirement:

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'Ihe primary benefit from a remediation action is the collective dose averted in~the future - the sum of the -

J

. doses received by the entire exposed population. Assume:

g 1

1.. ou have a location with residual radioactivity at a concentration CD,

L 2. The concentration' equivalent to 0.25 mSv (25 mreni)/yr (DCOLw) for the site has been determined (for soil or for building sus faces, as apprbpriate).

' 3. The residual radioactivity at a site has been adequately characterized so that the effectiveness of a remediation action can be estimated in terms of the fraction F of the residual radioactivity that the action

- will remove.

~

4. The ' peak dose rate occurs at time 0 and decreases thereafter by radiological decay.'

l

- The derived concentration guideline (DCGLw) is the concentration of residual radioactivity that would c result in'a total efTective dose equivalent to en average member of the critical group of 0.25 mSv (25 e mrem)/yr. Acceptable methods to calculate the DCGLw are discussed in guide Section C.I. Therefore, t

the annual dose D to the average member of the critical group from residual radioactivity at a -

1 concentration C is

- D = 0.025 un/pr x (18)

DCMy

' If a remediation action would remove a fraction F of the residual radioactivity present, then the annual

- averted dose AD ndividual o an individual is:

i t

C Fx 0.025 nndyr x

{t9)

ADm (undydperson)

=

The annual collective averted dose ADcoijeci;ye can be calculated by multiplying the individual averted -

dose, ADindividual, by the number of people expected to occupy the area A' containing the residual radioactivity.- The number of people in the area containing the residual radioactivity is the area A times -

the expected future population density Po for the site. Thus:

x - A x ' P - (20)

-ADe = F x 0.025nnvyr x

o

The annual monetary benefit rate at time 0, Bo, due to the averted collective dose in dollars /yr can be.

calculated by multiplying the annual collective averted dose AD ji,ctiy, by $200,000/ person-sievert co

($2000/ person-rem) (Reference 3)

M

=, $2000 E x ;F5 x 0.025 rentyr -

x.A x P o

(21).

The total monetary benefit of averted doses can be calculated by integrating the annual benefit over the-

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exposure time in years considering both thb present worth of future bsnefits 'and radiologidal decay. It is y

NRC policy to use the present worth of both benefits and costs that occur in the future (Reference 3),

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The equation for the present worth PW of a series of constant future annual benefits Bo($/yr) for N years =

Jat a monetary discount rate of r (per year) using continuous compounding is: =

j i

,e.;

l

=, -

'PW-=

B x p2) i re, t

i The continuous compounding form of the present worth eq uation is used because it permits an easy _

' formulation that includes radiological decay. If the annual benefit rate B is not constant but is decreasing from its original rate Bo due to radiological decay, the radiological decay rate acts like an additional '

discount rate that can be added to the monetary discount rate of decline so that the present worth factor PW becomes:

i

,UAW_1 PW=B G3) x o

(r t 1) eV 'W

~

w As N Equation 23 has the limit:

3 1

PjF =, B x

g4) o r4+

A;

+

- When the radionuclide has a very long half life (_0), the present worth of future bedefits PW will be inversely proportional to the monetary discount rate r. As (r + )N 0, Equation 23 has the limit:

n PW'=-B

'x N.

s95) o Thh total benefit B,oi i s the present worth of the annual benefits. B,i can be calculated by combining -

i iot equations 21 and 23:

' ??W - 1

. Bw = $2000 x P x 0,025 x C

"x A x Pg x 06)

DCOL,

'(r t A)eV +M 5

Now consider the costs of a remediation action, Cu.LAs a rough approximation, when one can achieve reasonable economics of scale, the cost of a remediation action Cu ill be proportional to the area to w

be remediated. Defining the cost per unit area coa as the proportionality constant, the costs included in (Cur are: (1) the direct cost of the remediation action itself, (2) the cost of waste disposal including its J shipping cost, (3), the monetary costs of workplace accidents during the remediation, (4) the monetary l costs of transportation accidents during the slupping of waste, and (5) the monetary value of the dose -

that remediation workers ceceive. Thus,

~

Cg =lCg x-A-

p7) l

~

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C 3

ff Both the benefits (Equation 26) and the costs (Equation 27) include the area A. Therefore when we take a benefit / cost intio by dividing Equation 26 by Equation 27, and the area A cancels out.

B c

,("W - 1 g = $2000 x F x 0.025 x P x x

o (29)

C Cm DCOL, (rt A)el"W u

What we are most interested in is the concentration C at which the benefit Biotal equals the cost Cgg.

4 Thus, in Equation 29, we set the ratio Biotal/CRA equal to 1. When this is done we can solve Equation 29 for the concentration C relative to the DCGLw or C/DCGLw:

C C

(r t 1) e('

• 4 #

m

DCOL,

$2000 x F x 0.025 x P e(' + W - 1 o

' Equation 30 is our result. Equation 30 can be used to detennine the concentration at any location for which a remediation action should be taken to meet the ALARA criterion. The equation appears complicated, but the calculation can be done in a few minutes with a hand-held calculator, and it only has to be done once for each type of remediation action at a site. Po, N. and r are constants. Generic values for Po and N are given in Reference 4 or may be determined on a site specific basis. Values for r are given in References 2 and 3. The only site specific information that the licensee needs is the cost per unit area, CUA, and the effectiveness F for each remediation action being evaluated.

References

1. W. J. CLINTON, President of the United States, Executive Order 12866, " Regulatory Planning and Review," 1995,

2. OfTice of Management and Budget, " Economic Analysis of Federal Regulations under Executive Order 12866, January 11,1996 (Available on the web at http://www1.whitehouse. gov?WII/EOP/OMB/html/misedoc/riaguide.html# select ).

3. NUREG/BR-0058, Revision 2, " Regulatory Analysis Guidelines of the U. S. Nuclear Regulatory Commission," 1995,

^

4. NUREG-1496, " Generic Environmental impact Statement in Support of Rulemaking on Radiological

. Criteria for License Termination of NRC-Licensed Nuclear Facilities," 1997.

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