Text

Revised Response to Request for Additional Information Related to Partial Site Release and Recent Site Survey Activities
	ML22089A098
Person / Time
Site:	Zion File:ZionSolutions icon.png
Issue date:	03/28/2022
From:	Van Noordennen G; ZionSolutions
To:	; Document Control Desk, Office of Nuclear Material Safety and Safeguards
References
	ZS-2022-010
	Download: ML22089A098 (100)
	v • d • e

z10N SOLUTIONS~ L-u==========-=-=-=-=-=--=

An E""'W...,._~

March 28, 2022 ZS-2022-010

U.S. Nuc lear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Zion Nuc lear Power Station, Units 1 and 2 Facility Operating License Nos. DPR-39 and DPR-48 NRC Docket Nos. 50-295 and 50-304

Subject:

Revised Response to Request for Additional Information Related to Partial Site Re lease and Recent Site Survey Activities Reference s:

1) Marlayna V. Doell, U.S. Nuc lear Regulatory Commission, Letter to John Sauger,

ZionSolutions, "Z ion Nuclear Power Station Units 1 and 2 - Request for Additional Information Related to Partial Site Relea se and Recent Site Survey Activities,"

dated August 19, 2021

2) Kim A. Conway, U.S. Nuc lear Regu latory Commission, Letter to John Sauger, ZionSolutions, "Z ion N uc lear Power Station Units 1 and 2 - Req uest for Additional Information Related to Partial Site Release and Recent Site Survey Activities,"

dated October 14, 2021

3) Gerard van Noordennen, ZionSolutions, Letter to U.S. Nuclear Regulatory Commission,

" Respon se to Request for Additional Information Re lated to Partial Site Release and Recent Site Survey Activities, and Notification of Foundation Pad Discovery," dated March 8, 2022

ZionSolutions received Requests for Additional Information (RAJs), related to the partial site release request and s ite survey activities, on August 19, 2021 (Reference 1) and October 14, 2021 (Reference 2). On March 8, 2022, ZionSolutions provided responses to the RAls (References 1 and 2) as documented in Reference 3.

In reviewing post-processing survey data, ZionSolutions identified that a conservative calcu lation of the minimum detectable act ivity for the investigation area s was made. Therefore, the responses to the RAls provided in Reference 3 have been revised to reflect the net count rate of the towed-array versus the gross count rate. This revision reflects a more realistic and lower discrete radioactivity particle activity sens itivity for identifying an area for investigation using post-proces s ing methods for the towed-array surveys.

The purpo se of this letter is to provide the revised responses to the RAls related to the partial site relea se request and site survey activities; the revised responses replace the previous responses,

prov ided in Reference 3, in their entirety. The revised re sponses to the RAls are pro v ided in the attachment to this letter. A revision bar is used to show where RAJ responses were revised.

101 Shiloh Bou levard, Zion

IL 60 099 (224) 789-4016

Fax : (224) 789-4 00 8

www.zio ns olu tionscompany.com ZionSolutions, LLC ZS -2022-0 10 P age 2 of3

If yo u shou ld have any question s regard ing this s ubmi ttal, please contact me at (860) 462 - 9707.

Re spectfu ll y,

Digitally signed by Gerard van Noord e nnen Gerard van ON: cn=Gerard van Noordennen, o = EnergySolution s, ou = Regulatory Affairs, email=gpvannoordennen @energysolutions.com, c=US Noordennen Date: 2022.03.28 1 2:32:02 -04'00 '

Gerard va n Noordennen Senior Vice Pre s ident Regu latory Affairs

Attachment:

Revi se d Re s pon se to Req u est for Add itiona l Information Related to Partial S ite Re lease and Recent Site Survey Activiti es

cc: Kim Conway, U.S. NRC Senior Project Ma n ager Regional Administrator, U.S. NRC, Region Ill Zion Nuclear Power Station, Units 1 and 2 Service List Zion Nuclear Power Station, Units 1 and 2 Service List

cc:

Ken Robuck Steven A. Reynolds President and CEO Manager, Nuclear Faci lity In spection E nerg y Solutions Divi sio n of Nuclear Safety 299 South Main Street, Suite 1700 Illin ois E mer gency Management Agenc y Sa lt Lake C ity, UT 8411 I 245 W. Roosevelt Road, Units 55 & 56 West Chicago, Illinois 60185 John Sa uger President and Chief Nuclear Officer Kelly F. Grahn Reactor D&D Senior Health Physicist Energy Solutions Illinois Emergency Management Agency 12 1 W. Trade Street, Suite 2700 Division of Nuclear Safety Charlotte, NC 28202 245 W Roosevelt Road, Building 8, Suite 55 West Chicago, IL 60185 Todd E iler Project Director Dan Eder D&D Engineering/Projects MPH, IPEM, LEHP Energy Solutions Interim Manager 121 W. Trade Street, Suite 2700 Lake County Emerge nc y Management Agency Charlotte, NC 28202 1303 N. Milwaukee Avenue Libertyville, IL 60048-1308 Gerard van Noordennen Senior VP Regulatory Affairs Energy Solutions 121 W. Trade Street, Suite 2700 Charlotte, NC 28202

Russ Workman General Counsel Energy Solutions 299 South Main Street, Suite 1700 Salt Lake City, UT 84111 ZionSolutions

ZS-2022-010 Attachment

Zion Nuclear Power Station, Units 1 and 2

Revised Response to Request for Additional Information Related to Partial Site Release and Recent Site Survey Activities ZionSoluti ons, LLC ZS-2022 -0 l 0 A tt achme nt

Zion N ucl e ar Power Station, U nits 1 and 2 - Reque s t for Additional Information Related to P a rtial Sit e Release and Recent Site Surve y A cti v ities, dated August 19, 2021, and October 14, 2021

REQUEST FOR ADDITIONAL INFORMATION:

The NRC staff is reviewing the Zion FSSR and the associated partial site release request to e ns ure that the proposed removal of 128 survey units from the ZNPS IO CFR Part 50 license s demonstrates the ability of the site to meet the criteria for unrestricted release contained in Subpart E of IO C FR Part 20. The NRC staff has re v iew ed th e FSSR submittal s and supplement s pro v ided to date, as well as the results from the April 2021 inspection survey, and determined that additional information related to current radiological conditions at the site is needed to complete its review, as described in the following RAls. The information gathered in response to the se RAi s will be used, in part, by the NRC staff to perform additional risk a ssessments and /or dose calculations to obtain reasonable assurance that the Zion site meets the assumptions outlined in the Zion L TP and may be released from the ZNPS IO CFR Part 50 licenses without undue risk to public health and safety, or impact on the environment.

ZIONSOL U TIO N S OVERVIEW ZionSolut io ns und e rst and s t hat t h e NRC staff is seek in g additi o na l info rm at ion rega rdin g th e origin, re l ease, an d tra n sp ort of di sc rete ra di oac ti ve p art icles (DRP s) th at h ave been di sco vered at the Z io n s it e. We fur t h er und er st a nd th at N R C is see kin g co n firmatio n th at work at th e s ite was pe rfo rm ed in acco rd a nce w ith t he Z ion L ice n se Te rmin ati on Pl an (L T P ). T h is in for m a ti on is im porta nt in o rd er for th e staff t o have co nfid e n ce th at th e sit e m ay be r e le ase d fro m th e Z ion Nuc lear Powe r Stat io n (ZNPS) IO CF R P art 50 li cen ses w ith o ut un d ue ri sk t o pu b li c hea lth and safet y, o r imp act on th e e n v iro nm e nt.

ZionSolutio ns be li eves t h at th e iss ues rai se d in th e RAis ca n be s umma ri ze d as fo ll ows:

Wh a t i s the o ri g in of the DRP s at t h e Z io n s it e an d h ow did th ey get w he re th ey are?

Why we re t he D RP s not d et ec te d durin g th e FSS?

Was t he work at t h e s ite co ndu cted in acco rd ance w ith th e L TP?

How ca n ZionSo lution s a n d th e NRC be co n fident t hat t here are not DRP s re m ai n in g at th e site that p ose an u nacce p ta bl y hi gh r i sk t o a fut u re occ upant?

In the fo ll ow ing pages, Z ionSolut ion s p rovi d es an swer s to ea ch of t he RA i s t h at a dd ress t hese q uestions. We be li eve th at th e tota li ty of th is in fo rm at io n is ad equ ate to ju sti fy u nrest ri c te d

Page 1 of 96 ZionSolutions, LLC ZS-2022 -01 0 Attachme n t relea se of th e s ite. In this overview, we have sum m arized t he ke y iss ue s and the justification for our conc lu s io n s.

Origin and Transport of DRPs. T h e DRP s t h at were detected and remediated during FSS and ORJSE independent ver ificati o n s ur vey s come from a var ie t y of so ur ces. While we can no t prec ise ly id ent ify th eir so ur ce o r th e pathwa y to th e locatio n at which the y were di scovered, we ca n infer both from th e radioisotop ic content, type of partic le, and our under sta ndin g of act ivitie s at the site. Thi s in forma ti on is u sefu l in order to bo und the sco pe of the prob lem ; however, it is important t o recognize that these d eta il s are not adequate to absolutel y co nfirm that no DRP s wi ll remain o n-site. As exp la in ed below, w ith the add iti o na l s urve y an d sa mpling mea sures that h ave been implemented by Z ionSolutions, we believe th ere i s reasonable a ss urance that th ere will be n o DRPs po sin g an un acceptab ly hi gh ri sk rema inin g on -s ite.

Adequacy of FSS and DRPs. T h e FSS meth o dolog y is de s ig ned con s ist e nt with NRC g uid ance and industry best practice to d etec t di str ibu ted activity that exceeds the d er ived conce ntrati on guideline leve ls (DCGLs) so t hat these areas m ay be remed iated. It is not desi g n ed spec ifi ca ll y to be sens iti ve for the detection ofD RP s. This notwithstanding, 19 DRP s were detected during FSS. T h at a ll DRP s were not detected is n ot a n indi cation that the FSS was not adeq uate to perform its intend e d function. Ne ither is it an indic at ion that FSS was not exec ut ed properly.

Z ionSolution s h as d es ig n e d a nd impl e ment ed an a dditi ona l survey plan to d e te ct and rem ediat e DRP s. The dat a quality o bj ectives (DQOs) of thi s s urvey and the equipment used supplem e nt the FSS and provide confi d e nc e that any remaining DRPs that wo uld pose a n un acceptab ly hi g h risk have been identified and remediated.

Work in accordance with the LTP. Z ionSolutions h as cond ucted the decommis s ioning of the ZNPS in accordance with th e requirement s an d comm itm e nt s co nta in ed in the LTP. The execut io n of certain portions of this work ( e.g., timing, so ur ce and depth of fi II, class ificati o n of s urvey unit s, identification of radionuclid es of co ncern (ROC), and d ose calculations) has come into que stion due to the id e ntification of DRPs. As d escri be d be low, we are confident and h ave provided ev id e n ce that th e work was d o ne in accordance w ith the L TP. Z ionSolutions ha s considered if the LTP s ho uld have been modified in response to the detection of and ca lculati on of dose from DRPs, and if so, w h e th er the adva nc e approval of the NRC is required. We ha ve concluded that revi s ions to Chap ter s 5 and 6 are necessary, and we are preparin g and w ill submit a li cense amendment request (LAR) for NRC approv al.

The DRP Survey Plan. Z ionSolutions h as de signed and implem ented a sur vey plan, " Survey Plan for Di sc rete Radioactive Particle Identification a nd Remediation," ZS -L T-07, Revision 1 (the " DRP S urvey Plan " ), 1 specifica ll y for t h e purpose of d etec tin g and removing DRPs. The

1 Z ionSo luti ons ZS-LT-07, " S urvey Plan for Di screte Radioactive Particle Identifi catio n and R emediation " R evision I, D ece m her 2 02 1.

Pa ge 2 of96 Z ionSol ution s, LLC ZS - 2022 -01 0 Attac hm e nt DRP S urvey Pl a n is in c lud e d as part of th e Z io nSo l utions r es p o n se to RA l-10. Fo ll o win g th e exec uti o n o f the DRP S urv e y Pl an, th e re w ill b e n o kn own DRP s re m a inin g o n th e Z ion s ite.

B ase d o n th e co mpl et io n of th e s u rvey a nd in ves ti ga ti o n s, an es tim a te of th e numb e r a nd a cti v ity of DRP s th at m ay h y p o th eti ca ll y remain h as b ee n m a de a nd th e d ose a nd ri s k fr om th e hypot h et ica l DR P s have b ee n est im at e d. Any D RP s th at do re m a in wi ll not co nta in s uffic ie nt ac ti vity to p ose a n un acce p ta bl e r is k t o a futur e occ up a nt of th e site.

Pr ese nc e of DRP s at th e Zi o n S ite. D espi te t he exte nsive wor k to detect a nd re m ed iate DRPs,

th e pros p ec t of DRP s h y p oth et ica ll y re m a inin g o n th e Z io n s it e ca n not be di s mi sse d. Co n s is te nt w ith N R C g uid ance in NUREG -1757, Z ionSolut ions has u se d a ri sk-b ase d app roac h a s d esc rib e d be low t o a ssess th e ri s k o f dose fr o m a DRP t ha t m ay hy p oth eti ca ll y b e le ft o n th e s ite. Th e p ropose d ch a n ge w i II be in co rp o rate d int o th e L TP by I ice n se am e ndm e nt and w ill s uppl e m e nt h ow Z ionSo luti ons d e m o n s tra tes co mpli an ce w ith th e d os e c rit eria fo r unr es tri c t e d re le a se in Subp art E of 10 CF R Part 2 0. B ase d o n o ur p ro b a bili ty a na lys i s, it is o ur es timati o n that as m a ny as 3 1 DRP s co uld h y p o th e ti ca ll y rem a in o n t h e s it e. We are co nfid e n t b ase d up o n o ur impl e m e nta ti o n of a dditi o n a l s urvey a nd sa mplin g m eas ur es th at n o DRP s th at co uld d e li ve r a s ig ni fica nt d ose to a memb er of t h e public, includin g a fu tur e oc cup a nt, re m a in a t th e s it e. T h e an a lyses t o d oc um e nt a nd ju s ti fy thi s c o nc lu s io n ar e d esc r ib e d in d e t ai l in o ur res p o n se t o RAI-10.

Our de tailed r es p o n ses t o eac h o f the NRC qu e sti o n s e numerat e d in th e RAis d a ted Au g u st 19,

2 021, and O c t o b e r 14, 2 0 2 1, ar e g ive n bel ow. T hese re sp o ns es ju s ti fy ou r c o nclu s io n that th e ZNPS 10 CF R P a rt 50 li ce n ses c an b e t e rmin at e d w ith o ut undu e ri sk to public hea lth and safety,

o r imp ac t o n th e e n v ironm e nt.

NRC RAI-la:

For each particle or sample identified during the April 2021 inspection survey and described above, please explain to the extent possible: The likely origin of the particle or material identified in the sample (e.g., activated metal, bioshield concrete, irradiated fuel fragments, etc.)

from decommissioning operations, including the hypothetical radionuclide mix for each type of particle based on the reactor operational history of both ( e.g., fuel bum up and activation).

ZIONSOLUTIO N S RESPONSE:

Whil e th e sp ec ifi c o ri g in fo r eac h particl e is unkn ow n, Z ionSo luti ons h as p os tul a te d th e m ost like ly o ri g in fo r eac h particl e b ase d prim a ril y up o n th e ra dionuclid e p ro file o f e ac h. A s dis c u sse d in th e Fe bruar y 10, 2 02 1, resp o n se to RAI-11 b, th e I ik e ly o ri g in of th e m aj o rity o f p a rticl es fo und in s ite so il are fr o m r eact o r v e ss el in te rnal s (RVI ) seg m e nt at io n. Based up o n the ra di o nu c lid e p ro fil e o f p a rti c les di sco ve re d by th e O ak Rid ge In s ti tu te fo r S ci e nc e a nd E du cat io n

P age 3 of 96 ZionSolut ions, LLC ZS - 2022 - 0 10 Attac h ment (ORISE) du r in g the A p r i l 2021 ins p ect ion survey (as doc um e nted in fi n a l report 5271-SR - 09 - 02),

ZionSolutions be l ieves th at t h e a ddi t io n a l part ic les originate d from fue l frag m en ts, inte rn a l containment concre t e (or iginating from under vesse l or the b ios hi eld), or we lding rod resid ue.

The interna l containment concrete was l ikely in tro du ced in to th e soil dur in g waste ha ndli ng operat ions. The postu lated origi n a nd hypothet ica l radionuc li de mix for eac h particle is s h own below in Ta bl e 1.

Tabl e 1 - Particle Origins and Hypothetical Radionuclides Sample Likely Origin Hypothetical Radionuclides S0112A RVI seg m entation Co -60 S0116 RVI segmentation Co-60

S0 120 Internal contai n ment co ncrete Co -60, Ba-133, E u-152, E u-1 54, P u -238, P u-239 /240

S0124 RVI seg m entation Co -60

S0126 F u e l fragment Co - 6 0, Cs - 137, E u-154, Eu -1 5 5, A m-24 1, C m-244, Pu-238, Pu-239/240

S2 04AEu Int ernal conta inm en t co n c r ete Co -6 0, B a-133, E u-15 2, E u -15 4, Pu-238, Pu - 239 /240

S203B We ldin g ro d resi du e Ra - 228, Th-228, T h-230, T h-232, U -234, U-238

527 1-S - 203A Th We ld in g ro d resi du e Ra -228, T h-228, T h-230, T h-232, U-234, U -238

NRC RAI-lb:

For e a ch particle or s ample id e ntified during the April 2021 inspection surve y and described above, please explain to the e x tent possible : The s ize range of particles expected to be produc e d by decommissioning operations for the three types of particles identified (i.e., Co-60 metal,

po ss ible activated biosh ield concrete, possible activated fuel fragm e nt ). Specificall y, for the types of cutting op e rations ab ove and belo w water and demolition acti v ities that w ere performed at Zi o n, the range of ex pected particle size s should be identified, along with technical reference s for the expect e d s ize range where available.

2 " Indepe ndent Confirmatory Su rvey Summary and Resu lts Assessing th e Presence of Res idu al Rad ioac t iv ity and Radioactive Particles w it hin Se lect Land Area a t the Zio n N u clear Powe r Station, Zion, Illin o is," Oak Ri dge Institute for Science and E du cation, Report No. 5271 - SR-09-0, Septe m ber 3, 2021.

Page 4 of 96 ZionSolution s, LLC ZS-2 022-010 Attachment ZIONSOLUTIONS RESPONSE:

Co-60 Metal Particle Size. F o r the decommi ss ionin g o f Zion, a mechanical c omplex tool s ys tem for und e r w ater RVI se g mentation w as u s ed. During the mockup te sting of this sy stem for Z io n, particl es p ro du ce d we re appro x im at e ly l mm in diam e t e r and less than l mm thick, as di sc usse d in th e Fe bruar y 10, 2 02 1, re sp o n se to RAI-11 b. A cc o rdin g t o th e E PRI R eport,

"C h aracteri z ati o n and Man age m e nt o f C uttin g D e bri s During Plant Di s mantlement, " mech a ni ca l tec hniqu es fo r RVI segm e nta ti o n produc e d e bri s in th e 2 mm t o 6 mm ran ge, w ith n o airb o rn e debri s. 3 Fuel Particle Size. The fuel particl e ma ss w a s e stimated using the activit y and th e specific ac ti v ity (Bq /k g) of Pu-23 9 in sa mple S 01 26 (s h ow n in F ig ure 1), as d oc um e nt e d in the ORI SE rep o rt 5271-SR-09-0.

Figure 1 - NRC Radiological Toolbox Specific Activity for Pu-239

~ Summ.,y Tablt fo r Pu*l.39 X Summary Decay Data Table for Pu-239

H -Lde 2 41 IE*4 V Specific ActMly 2 295E* 12 Bq I kg Mode 4 Source ICRP-07 NOX

Frequency Energy Mean Energy I:YI IYi

El I:YI

El I I:YI Radjation Number Ital) (MtY!oll (Mey)

Gamma rays 20 7 9 758E-04 6 399E*OS 6 658E-02 X rays 74 3 042Ect00 1 014E-03 3 335E-04 IC electrons 1016 3 045!:-0 1 S 829-03 1915E-02 Augtr electrons 15 2 590E+OO 1 625E-03 6 276E-04 Alpha pa rticles 52 I OOOE+OO 5148E +OO 5 148E+OO Alpha RecOII Nuclei 52 1 OO OE*OO ~ 8 768E-02 Totll Emitted Ene rgy 5 244E+OO

Not a Yi = 1111ensity of radJation I El = tn rgy ol radiaoon,

II Pin II

OK

The Pu-239 specific activiti es in GBq/ g, Bq /g, and pCi /g are shown in Table 2.

3 " Ch aracteri z ati o n a nd Manage ment of C uttin g D ebri s Durin g Plant Dismantl e m ent," Th e Electri c P ow er R esea rch In stitut e, Jul y 2 8, 2015.

Page 5 of96 ZionSolutions, LLC ZS-2022 -0 I 0 Attachment Table 2 - Pu-239 Specific Activity in various Units Specific Unit Activity 2.30E+00 GBq /g 2.30E+09 Bq /g 6.20E+ l0 pCi /g The mass of the Pu-239 in the partic le can be estimated from the reported activities in 5271-SR-09-0 by dividing the activ ity in GBq /g by the specific activity in GBq /g in Table 2. T h e estimated Pu-239 mass of the particle is shown in Table 3.

Equation 1 - Calculation of Particle SOI 26 Pu-239 Mass

Apu-239 X 3.70£-11 GBq/pCi MPu-239 = SAPu-239 x 1000 g/kg

where MPu-2 39 = the mass Pu-239 in the S0 126 particle

APu-239 = the activity of Pu-239 in pCi

SAPu-239 = the spec ifi c activity of Pu-239 from Figure l in Bq /kg

3. 70E-11 = the conversion factor for pCi to giga Becquerel where 1 pC i = l.00E -

12 Ci a nd 3.70E+ 10 Bq = 1 Ci and l GBq = l.00E + 09 Bq.

Table 3 - Estimated Pu-239 Particl e Mass of Parti cle SOI 26

Radionuclide Activity Activity Mass (pCi) (GBq) (g)

Pu-239 7.74E+03 2.7898E-0 7 l.22E-07

According to the Wo rld Nuclear Organization4, as seen in Fig u re 2 below, approximate ly 5 kg of Pu-239 are containe d in one tonne (1,000 kg) of spent fuel in a power reactor at discharge (approximately 2 years).

4 Plutoni um in the Reactor Core, World Nuc lear Organizat ion Plutonium Webpage.

Page 6 of 96 ZionSolutions, LLC ZS-2022-0 l 0 Attachment Figure 2 - Plutonium in the Reactor Core, World Nuclear Organization Plutonium Webpage

Plutonium in the reactor core

6

5

,i!

0 j3 i---- -#- -+------1-------1

l. 2 i

~ 1

0 1 2 3

Yea nf or

Equation 2 - Fractional Mass Pu-239 per Mass of Spent Fuel

5 kg x 1000 g/kg FPu-23 9 = 1000 kg x 1000 g/kg = 0.005 g Pu-239 per g spent fuel

where F P u-239 = Fractional mass of Pu-239 per mass of spent fuel

Therefore, the mass of Pu-239 in particle S0126 (l.22E-07 g) is equivalent to 2.43E-05 g of spent fuel as follows.

Equation 3 - Mass of Spent Fuel Bas ed on Mass of Pu-239 Msp = g = 2.43£-05 g SF 1.22£-07 g Pu-239 0.005 Pu-239 SF g

Spent fuel contains 941 kg /tonne of U-23 8 or 0.941 gram U-23 8 per gram of spent fuel. 5 Based on this, the U-238 or uranium oxide mass is shown in Equation 4 as 2.29E-05 gram.

Equation 4 - Mass of Uranium Dioxide based on U-238 Mass and Fraction of U-238 per gram of Spent Fuel Mu = 0.941 --- x 2.43£-05 g SF= 2.29£-05 g U-238 g SFg

Converting the U-238 mass to volume using a uranium dioxide density of 10.97 g/cm 3 estimates a particle volume of 2.09E-06 cm 3 using Equation 5.

5 From Radioactivi ty. E U. com

Page 7 of 96 ZionSolutions, LLC ZS-2022-010 Attachment Equation 5 - Volume of Uranium Oxide in Particl e S0126 Based on Mass of U-238 and Density of Uranium Dioxide Vu0 2 - 9 - 2.09£ - 06 cm _ 2.29£ - 05g _ 3 10.97-3 cm

Using E quation 6, the diamet er of a s ph erica l partic le of that vo lu me is 159 µm.

Equation 6 - Particle Diameter Based on Sphe r ical Volume V = -rrr4 3 3

D = 2 x -V )1 /J X 10,000 - = 159 µm µm

( 3 -- = 1.59£ -0 2 cm /4 rr cm

where D = diameter of the ura nium oxide particle in cm 2 = double the radius lengt h to that of the diameter V= 2.09E -06 cm 3 volume of the uranium oxide sphere Activa ted Concrete Size. ZionSolutions is unable to estimate a size for a DRP consisting of activated concrete. DRPs of this nature were first identified b y ORISE in the April 2021 inspection survey, and particle sizes were not presented in their final report, 5271 - SR-09-0.

Concrete demoli tion debris on-site was require d to b e reduced to a size sma ll er than 10 in ches in di ameter before it was packaged a nd shipped off-site or reuse d as backfill. As su ch, residual activated concrete discovered on-s it e would be expected to be sm aller than 10 inches in diameter. A particle wo uld clear ly be much sma ll er, but we h ave no data to postulate a specific size range.

DRP Size Change over Time. It is important to recognize that these projected particle sizes may change due to weather in g and other e n vironme nt a l in fluences over the 1,000-year comp li a nce period. These partic le s ize changes wi ll affect the potential dose to a future occupant.

ZionSolutions accounte d for particle size changes in order to d evelop dose estimates in response to RAI-10. Our ana lys is of how particle s may change in size and the resu ltin g dose estimates is de scribe d in the response to RAI -10, Specific Co n sid eration 3b.

NRC RAI-lc:

For each particle or sample identified during the April 2021 inspection survey and described above, please explain to the extent possible: A description of how the particle or material transported from the contamination source to where it was found during the April 2021 inspection survey, as well as the potential timing or time range of when the particle was transported to that location.

Page 8 of96 ZionSolutions, LLC ZS - 2022-0 10 Attac hm ent From p. 12 of the RAl letter : "The licensee should attempt to determine the origin of this contamination, or provide reasonable assumptions regarding the potential origin of this

[enhanced thorium] material." And"... the licensee should state whether the thorium material is likel y a result of decommissioning operations, such as cutting or welding metal components; whether it was in advertently imported... "

ZIONSOLUTIONS RESPONSE:

ZionSolutions believes that partic les were introduced to the environment via the fol lowing events:

1. Partic les in the form of shavings from RVl segmentation were likely introduced into the soi l via the transportation of the 8-120 liners loaded w ith RVI segments. The origi n al incident in 2014 started when an 8-120 liner was transported from the south array storage area to the parki n g area to the north of the o ld NGET build ing. It is believed that the contents of the liner dried out. When Radiation Protect ion was surveying the veh icle for exit of the site, e levated read in gs were e ncountered and a DRP was captured. At this time, the exit to the site was closed for a ll vehicles a nd personnel, a nd FSS personne l were brought in, along with 2" x 2" sodi um iodide (Nal) detectors, to help locate and capture other potential DRPs from this event. These scan surveys covered the so uth-n orth trave l route and extended east-west as necessary to ens ur e that all particles were captured.

Personnel exiting the site had to perform a hand and foot frisk prior to entering the portal monitors. These mitigating m easures that were immediately implemented after the event limited the spread of contam in ation to other areas of the site. While ZionSolutions believes that these measures were useful in limi ting co ntamination, this event likely is responsible for the majority of the DRPs identified o n-site.

2. Partic les in the form of fue l fragments or metal, entered the soi l via a lack of negative pressure and the movement of potentially co ntaminate d equipment and large co mp on ents through the equipment hatches of each Containment Building prior to the erection of the waste loadout tents. This source term origin was mitigated once the waste loadout tents were erected in ear ly 2017.

3. Particles in the form of concrete material associated with interna l containment generated during demolition were likely in troduced into the soi l du ring waste handling operations.

ZionSolution s believes waste handling operations to be the source of contamination based on the location and radionuc lid e contents of the part ic les identified by ORISE during the Apri l 2021 inspection survey.

4. Particles containing thorium were likely introduced int o the soil during welding activities, which frequent ly occurred throughout decommissioning both inside buildings and in outdoor areas. It was not uncommon to identify elevated areas of radioactivity during

Page 9 of96 ZionSolutions, LLC ZS -2022 -010 Attachment sca n surveys of building s and soil and identi fy welding rods to be th e so urc e of the elevated activ ity. While this activit y was remediated w h en di scove red, it i s pos s ible that an indi v idu a l DRP escaped detecti o n and rem e di ation.

Z ionSolut ions performed a review d escr ib ed in th e respo nse to RAJ-] n to determine if ot he r events co uld ha ve introduced DRP s into the e n viro nm ent. Based upon th is review, Z io nSolution s does not be li eve that a ny events other th a n those d esc rib e d above contr ibut e d t o the pre se nc e of p artic le s or contami nated debris at the s ite.

The fo ll ow in g timeline s ummari zes the timing o f potential release s from the se events, as well as actions taken to remed iate the release s.

20 12 thro ug h 2 014: Segmentation of reactor vesse l and re actor vesse l interna ls.

2012 thr o u g h 2017: Co ntainment equipment h atc hes expanded and open until the waste tent structure s were constructed in January and February 2017.

Se pte mb er 20 14 : Sto rage o ut s ide of 8-1 20 lin ers co ntainin g reactor int e rn a ls seg m e nt s,

loadin g of the 8-120 liner in an overpack, a nd transportation across the s ite.

September 24 and September 25, 2014: S urvey, detection of particles, and reme di ation of the co nt ami nated areas (s urvey unit s 1022 1A, 10221B, 10 221C, 10202, 10208, 10206,

10 2 04, and 10 2 0 3).

June 3, 2015: The area north of Unit 2 Conta inm ent was established as a temporar y radioactive materi a ls area for th e purp ose of containing severa l pieces of seg mented st eam generator components awaiting lo adout int o railcars. Particle s were detected in th e so il north of Un it 2 containment during the down-po sting survey.

J un e 3 thr o u g h June 11, 2 015: Surve y, detection of particles, and remediation of the co ntamin ate d areas (survey units 1220 1A, 12201B, 12201 C, 12202A, 12202 B, 12202C,

12202D, 12202F, 12109, a nd 12111).

January and February 2017: T h e conta inm ent waste tent structure s were erected and interior demolition of U nit 1 and Un it 2 Containment Buildin gs commenced.

January 29, 2018, thr o ug h March 1, 2018: Rem ove d debri s from U nit 1 under vessel.

February 2, 2 018, throu g h Apri l 5, 20 18 : R e mo ve d debri s from U nit 2 under vesse l.

Once introduced into the environme nt, the likel y tran sporta tion path ways for particles are surface wa ter flow (runoff durin g heav y rains) and /or heavy equipme nt and vehic le movement.

In immediate re sp o n se to th e events de sc ribed above, and in respon se to th e d etec ti o n of DRP s at a ny time durin g decommissioning, bia sed s urv eys were co nducted and the DRP s were succe ss full y remediated. While thi s was th e case, DRP s were st ill int e rmittentl y detected

Pa ge 10 of 96 ZionSolutions, LLC ZS-2022-010 Attachment throughout decommissioning at different stages, durin g radiological assessments (RA), FSS, or even after FSS. The most recent example of the detection of DRPs after FSS complet ion is the April 2021 in spect ion s urvey conducted by ORISE, in which eight DRPs were identified.

Because the DRP s were id e ntifi ed post-FSS and, in some cases, their radiological c haract er istics differed from the historical DRPs discovered at th e s it e, Zio nSo luti ons designed and implemented the DRP Survey Plan to address the presence of DRP s o n-site. The su rvey de s ign included a 100% gam ma scan of the s urvey units of interest us ing a 6-detector (2 " x 2 " Nal) towed array and sys tematic samp ling us in g a pre sence/absence design. The DRP Survey Plan is described in detail in the response to RAI-10.

NRC RAI-ld:

The most likely cause for why the particle or material was not found in licen see surveys.

ZIONSOLUTIONS RESPONSE:

The most likel y cause for why particles or other materials were not identified during licensee surveys is that the DQO development process for the surveys was not designed to detect particles. Had that been the intent, different DQOs (e.g., use of slower scan speeds) wo uld have been implemented.

It i s important to note that during active decommissioning, 255 particles were identified and remediated and another 25 particles were identified and remediated during FSS or RAs, for a total of 280 particles discovered by ZionSolutions using the standard instrumentation and survey methodologies in use at the time. So as designed, the surveys were adequate to detect the majority of particles on-site.

ZionSolutions implemented the DRP Survey Plan to provide high confidence that no particles remain on-site that cou ld deliver a significant dose to a member of the public. The s urvey plan included DQOs and survey methodologies that focus on DRP detection and remediation.

NRC RAI-le:

Whether these areas received an ORISE confirmatory survey in their final condition.

ZIONSOLUTIONS RESPONSE:

Survey unit 12201B did not receive a confirmatory survey during the FSS confinnatory surveys performed by ORISE in Januar y 2020, when the survey unit was in its final condition. However,

s urve y unit 12201B was included in the scope of the April 2021 ORISE inspection survey, but the survey was limited to a small portion of the survey unit and the intent of the s urvey was to identify particles, not to confirm FSS findings. Survey unit 12201 B was not impacted by final site grading.

Page 11 of 96 ZionSolutions, LLC ZS-2022-010 Attachment Survey unit 12203 D did recei ve an ORIS E confirmatory s urvey durin g the Januar y 2 020 s ite visit, as documented in th e ORISE Fi n a l Repo rt 527 1-SR-08-0. 6 Survey un it 12203D was n ot impacted by final site grading. Si nce the ORJSE confirmator y survey in Januar y 2020, a portion of th e su rvey unit was subject t o investi gat io n durin g the Apri l 2021 in s pection s urve y. FSS ha s since been rep erfor m ed in urvey unit l 2203D, a nd the urvey unit wa a lso within the scope of the DRP Survey Plan.

T he table b e low li sts th e survey unit s where part icles were identifi ed (d urin g th e e n t ir e proj ect) and w hether or n o t they rec e ive d an FSS confirmatory survey b y ORlSE.

Tabl e 4 - Survey Units with Particl es I dentifi ed that R eceive d ORJSE FSS Confirmatory Sur vey S u rvey U nit FSS Co nfirm atory S u rvey U nit FSS C onfirm a t o r y 10 202 B Ye s 12 104 No 10202D Yes 12 106 No 10203A Yes 12109 No 10203F No 12111 No 10204 B No 121 12 Yes 10 204 D No 121 13 Ye s 10 206 D Ye s 1220 1A No 10207A Yes 1220 1B No 10207B No 12201C No 10 207C No 12201D Ye s 10209A Ye s 12201E No 10209C Yes 12202A No 10209 E Ye s 12202 B No 10214 E Yes 12202C No 10214F Yes 12202D No 10220A Yes 12202F No 10220G Ye s 12203A Ye s 102201 Yes 12203C Yes 10221C Yes 12203D Yes 10 22 1D Ye s 12204A Yes

6 "Ind e pe nd e nt Co nfirmatory Survey Summary and R es ults of the Remaining Land A reas at the Z io n N uc lear P ower Station, Zion, Illin ois," Oak Rid ge In st itute for Science and E du ca ti o n, Rep o rt o. 527 1-SR-08-0, A pril 2 4, 2020.

Pa ge 12 of 96 ZionSo luti ons, LLC ZS-2022 -010 Attachment NRC RAI-lf:

If the area received a confirmatory survey in its final condition, provide an estimate of whether the particles were present and missed during the confirmatory survey or were transported to the area after th e confirmatory s urv ey du e to other site activities.

ZIONSOLUTIONS RESPONSE:

ZionSolutions is unabl e to estima te whether the p a rti c les were present a nd mi ssed dur in g the confirmatory s urve y or were transported t o the area after the confirmatory s urvey due to other s ite activities (e.g., personnel and veh ic le traffic). Z ionSolutions beli eves both sce narios to be equa ll y l ikely.

As discussed in the response to RAI-ld, the most lik e ly ca u se for w hy DRPs were not id entified during li censee s urvey s is that the DQO development process for th e s urvey was not designed to focus o n the d etectio n of DRP s.

NRC RAJ-lg:

Given the observations in the survey units listed above, as well as any additional observations resulting from ongoing licensee activities under the Final Status Survey Due Diligence Plan,

provide an explanation for why the licensee surveys are adequate.

ZIONSOLUTIONS RESPONSE:

The licensee s urveys were cond uct ed fo ll owi n g the p rocess for performing FSS in accor danc e w ith t he LTP, MARSS IM 7, and oth er regulatory g uidan ce document s. As s uch, ZionSo l utions believes that the surveys were con duct ed in accor d ance w ith b est indu stry p ract ice. The lic e n see surveys were designed to find unifom1l y distributed contam in ation and were adeq uat e and successfu l for that purpose.

Particles are a so urce term, and it is ZionSolutions ' intention to n ot leave any particles in s ite so il th at present an unacceptabl y high risk. ZionSolutions accomp li s hed this by performing a 10 0%

s urface area sca n in su r vey unit s 12201B, 12203D, and 34 a dditi onal s urvey unit s wit hin the scope of the DRP S urvey Plan u s ing appropriate DQO s and s ur vey methods w i th se nsitivit y sufficient for the detection of partic les. 8

7 "Multi-Agency Radi atio n Survey and S ite In vestigat ion Manual (MARS SIM)," NUREG-1575, Rev is ion I, U.S.

uclear Re g ulat ory Co mmi ss io n, A ug ust 2000.

8 See Co nn ec ti cut Yankee Atomic P ower Co., 58.R.C. 262, 297 -299 (2003) (fi nd ing that Connecticut Yankee 's complia nce with MARS SIM pro v id es a suffici e nt p lan for dete ct in g hot particl es in its L TP, with a se parat e o pini on not in g that a li censee cannot im plement a det ec ti o n plan until th e fina l site survey res ults are ava il a ble).

Page 13 of96 ZionSolut ion s, LLC ZS -2022-0 10 Attachme nt Within the DRP Survey Plan, ZionSolutions ta rgeted survey unit s that h ad the potential t o contain DRPs. In determining w hat s urvey unit s t o target, Z ionSolutions se lected survey uni ts:

where c lean co ncr ete demolition debr is (CC DD ) was t e mp orarily staged or transported through after comp letion of FSS

where waste loado ut areas resided

with areas of e levated ac tivity identified by ORJSE durin g th e April 2021 inspection s urvey

that were adjace nt to C lass 1 s urvey unit s (e.g., survey units 10214, 10213, 10212) where particle s o r e levated areas h ad bee n previo u s ly id e ntified

The ratio nal e for survey uni ts not includ ed in the DRP Survey Plan includes a combinat io n of the fo ll ow in g:

Z ionSolutions assessment of the so ur ce and tran sport of the DRPs that h ave been identified did not g ive a n y indic at ion that th e survey unit would contain DRPs.

DRPs were n ot d etected in pri or surveys.

FSS was performed in th e s urvey unit w ith no id entificat ion of DRPs.

ORISE performed an FSS co nfirm ato ry s urvey or ot h e r ind epen d ent verifica ti o n s u rvey in the survey unit with no identi ficatio n of DRPs.

Surveys performed during final s ite gra din g did not identi fy DRPs.

NRC RAI-lh:

Given that the licensee's FSS and other survey activities did not identify these particles or other radiological material, provide a discussion to support reasonable assurance that there are not similar particles in other areas at a concentration level or to an extent that might challenge the unrestricted release criterion of 10 CFR Part 20.

ZIONSOLUTIONS RESPONSE:

ZionSolutions has eva luat ed the like ly sources and transportation pathways of particles on-site.

Ba se d on this evaluation, survey units of medium to high r isk were included in the DRP Survey Plan to undergo a 100% scan s urvey with instrumentation of the appropr iate sensitivity and particle-specific DQOs. Because the DRP Survey Plan was designed to identify and remediate any remaining particles o n-site, it p rovides reasona bl e ass uran ce that DRPs th at may have b een mi ssed during prev io u s s urveys were d etected a nd remediated a nd there are no partic les remaining on-site to c h a ll enge the unr estricted release criter ion of 10 CFR 20. The foc u s of the surveys on survey units that were m ost lik e ly to contain DRPs provides reasonable ass uran ce that

Page 14 of 96 ZionSolutions, LLC ZS - 2022 -010 Attachment th e re are no DRP s in other areas of the s it e. If warranted, the scope of th e DRP Survey Plan was expanded as required b y bounding investigations or remediation.

NRC RAI-li:

When clean fill was placed over and surrounding the basement substructures in the Zion Power Block area.

ZIONSOLUTIONS RESPONSE:

Tab le 5 give s th e date s when clean fill was placed over and surrounding the ba seme nt structure s.

A re v iew was performed of the daily work reports for 2018 and 2019 to determine the dates for th e perfom1ance of fi 11 work. Off-site mat eria l ma y h ave come from o ne of two so urces (li s ted in the n o tes) and ma y be different types of material, but it i s all clean fill.

Tabl e 5 - Backfill Timeline Date Activity 02 /21/18 Began moving AB rubble pile from rail spur loading areas to south loading area (10221).

03 /28/18 Began receiving and stockpiling backfill for AB using clean, off-site material from Zion landfill. Placed on TB footprint (12205) for interim storage. TB footprint was under I&C prior to and during interim storage.

06 /15/18 Began AB backfill.

07 /20/18 Began backfill of Forebay using Turbine Building CCDD material.

07 /23/18 Began U2 Containment interior backfill (dome in place) using clean, off-site material from Zion landfill.

08 /02/18 Installed U2 Containment sacrificial backfill around perimeter.

08/10/18 Began backfill ofFHB using clean, off-site material from Zion landfill.

08 /10/18 Began Unit I Containment interior backfill (dome in place) using clean, off-site material from Zion landfill.

08 /27/18 Installed U 1 Containment sacrificial backfill around perim eter.

08 /28/18 Began Unit 2 Containment demolition.

09/26/18 Began Unit 1 Containment demolition.

12/10/18 Began backfill of Wastewater Treatment Facility.

01 /24/19 Began moving CCDD from 12202 to 12205, 12112, 12113 02 /27 /19 Began removing sacrificia l soil working from south to north. Placed in I 0207.

0 3/20/19 Began moving CCDD material to NW parking area.

04/17/19 Move of CCDD to NW parking area suspended.

06 /24/19 Began moving CCDD from 12205, 12112, 12113 to west loading area ( I 0206).

Page 15 of 96 ZionSolutions, LLC ZS-2022-0 l 0 Attachment

Date Activity 07 /11/19 Completed moves ofCCDD to 10206. ------- ----- ---------l 08 /05/19 Began back fill of power block area (where the sacrificia l soil was removed) to bring to final elevation. Used clean, off-site fill from Antioch quarry (Sand) otes:

CCDD was used to fill basements up to 3 feet below grade

Clean fill from the Zion Landfill was used as the top 3 feet layer in a basement

Clean fill from the Antioch quarry (sand) was used to bring the power block area back to grade after the sacrificial soil was removed

Sandstone gravel from off-site was used for roadways

A s noted in the last item of the timeline, the fina l cover soil (clean fill) was applied in A u gust 2 019 when ba sement backfills were complete. The DRPs that have b e en detected on the surface of the final clean fill applied to grade were likely attached to the equipment used to apply and grade the Antioch quarry sand. This equipment ma y have traversed the locations described in the re s ponse to RAl-lc and picked up DRP s.

NRC RAI-lj:

When final grading of the site commenced and was completed.

ZIONSOLUTJONS RESPONSE:

Final site grading of the site commenced on August 31, 2020, and was completed on September 23, 2020. A detailed timeline of final site gradi n g and supporting maps are included in the enclosure to this response (" Fina l Site Grading and Seeding Timeline with Maps " ).

Gamma scan surveys were performed prior to and after grading in all areas that were impacted by final site grading. T hi s includes areas where soi l was scraped, dispositioned, and w her e swales were created. No areas of elevated activ ity were identified during these surveys. Based on these surveys, the potential for final site grading to spread DRPs is low. Because DRPs were not identified during fina l site grading, the impacted survey units were not included in the scope of the DRP Surve y Plan.

NRC RAI-lk:

When final grading occurred for the area where concrete debris was stored.

ZIONSOLUTIONS RESPONSE:

As detailed in " Final Site Grading and Seeding Timeline with Maps " (provided in the enc losure to this response), grading occurred in surve y units where concrete debris was stored on September7, 9, 11, 14, 15, 16, 17, 18, 21, and22of2020.

Page 16 of 96 ZionSolution s, LLC ZS -2022 -010 Attachment NRC RAI-11:

When the final cover of seed bed (i.e., grass) on the final site grade was placed.

ZIONSOLUTJONS RESPONSE:

Seeding began o n September 11, 2020, and was completed on October 2, 2020.

NRC RAI-lm:

When ZNPS waste handling activities occurred in each of the locations where the particles and radiological material "c hunks " were found (south of the railroad track, south of the Auxiliary Building, southeastern portion of the site near the beach, etc.).

ZIONSOLUTIONS RESPONSE:

For each of the locations where particles and radiological materials were found, waste handling activities occurred throughout most of the decommissi o ning, with the first waste handling activities beginning in 2014, as described in the respon se to RAI-lc. However, interior containment concrete was not potentiall y introduced into the environment until January and February 2017, when the Unit 1 and Unit 2 tent structures were completed and interior demolition of the buildings commenced.

NRC RAI-ln:

Timing of any other operational events that could explain the origin or presence of the particles and radiological material "c hunks " of contaminated debris at the site.

ZIONSOLUTIONS RESPONSE:

ZionSolutions has the reviewed the operational and decommissioning history of Zion to determine if any other events (o ther than the eve nt s described in the responses to RAI-la and RAI-lc) cou ld explain the origin or presence of particles or radiological material at the site.

ZionSolutions reviewed condition reports that were written to assess the prospect that the events could have been a source of partic les or contaminated debris. Ba sed upon this re v iew,

ZionSolutions does not believe that any events other than those described in the re sponses to RAI-1 a and RAI-1 c contributed to the presence of particles or contaminated debris at the site.

For example, on March 8, 2017, the Unit 2 Containment waste loadout tent sustained rips due to hi g h winds. Accordi n g to the condition report (ES - ZION-CR-2017-0038, included in the enclosure to this response), little, if any, radioactive material was within the tent at the time of the breach. For thi s rea so n, ZionSolutions does not consider thi s event as a contributor to the relea se of particle s or material chunks to the environment. Prior to thi s, a ll handlin g of interior containment concrete occurred with in the Unit 1 a nd Unit 2 tents under contro ll ed conditions.

Page 17 of96 ZionSolution s, LLC ZS - 2022 -0 l 0 Attac hm ent NRC RAI-2a:

Please explain the process the licensee underwent to determine whether or not the information available since approva l of the Zion L TP has triggered an evaluation of the L TP change criteria.

In for m ati o n po te nti a ll y imp act in g th e Zi o n L TP lic e n s in g ba s is is in c lud e d in : a n RAJ re s po n se s ub mitte d in Feb ru a ry 2 0 2 1 (draft fo rm in No v e mb e r 2 02 0) rela te d to d ose fr o m p ote nti a l ra di o active parti c les left on the Z ion s ite, the April 20 2 1 in s pection s ur v e y re s ult s, and the Zion Fi n a l Statu s Su rvey Du e Dili ge n ce Pl a n.

ZIO N SOL UTIO N S RE S PO NSE:

During th e performa n ce of decom mi ss ioning act iv iti es, a ll e mpl oyees h ave b een tra in e d a n d ar e respo n s ibl e fo r execu ting work in co n forma n ce w ith th e LTP. It is th e res p o n si bili ty of th e C/L T Ma n ager to e nsure that wo r k is co ndu cted in co mpli a n ce w it h th e LTP. Tf any activ ity is id ent ifie d as p ote n tia ll y in cons iste nt w it h t h e LTP, it is th e res p o n si b i li ty of t h e C/LT M a n ager to co nd uct a rev iew and d eter m ine if a c h a n ge to th e L TP is or is n ot re qu ire d.

O n ce it h as b een d eter min ed th at a ZNPS act iv ity re qui res a c h a n ge to t h e LTP, AD -1 1,

" Reg ul a to ry Reviews, " is u sed to p erfor m an LTP eva lu at io n. T h e L TP eva lu ation is re qui re d,

for a ll LTP rev isio n s, t o a d d ress t h e li ce n se c riter i a in L ice n se Co n ditio n 2.C.(1 7). In a dditi o n to th e LTP eva lu at io n, t h e ac ti vity is re quir e d to be rev iewe d und e r 10 CF R 5 0.59. A D-11 prov id es g ui dance for t h e 50. 59 rev iew as we ll.

T h ere are 13 li ce n se ch an ge cr ite r ia in Attac hm e nt E -1 of A D-1 1 (the sa m e c o nd it io n s tha t a re listed in ZNPS Lice n se Co ndi tio n 2.C.( 17)). T h ese c ri te ri a appl y o n ce it h as b een d e te rmin e d th at a ch a n ge to t h e LTP i s n ecessa ry. As s u c h, th ey are n ot co n s id ere d in th e assess m ent of whet he r o r n o t t o ma k e a c h a n ge t o th e L TP. Z ionSolutions d oes not be li eve th at the re h as b een an y info rm at io n ge n era t e d t h at wo uld n ecessita t e a c h a n ge t o t h e L TP c h an ge c r ite ri a.

In response to t h is RA I, Z ionSolutions h as p er fo rm ed a rev iew of the res p o n se to S uppl em en ta l NRC RAI Q u est ion No. 11, s u b mit te d in Fe bru a ry 2 0 21, th e A p r il 2021 in sp ec ti o n s u rvey results, a nd th e res ult s of s ub se qu ent s ite s ur veys p erforme d by Z ionSolutions si n ce th e A pril 2021 in sp ect io n s u rvey in order to id e nt ify ac ti v iti es th at m ay h ave triggere d a c h an ge t o th e LTP. I n pr ep ari n g thi s respo n se, Z ionSolutions exa min e d t he fo ll owing act iv it ies:

1. D et ectio n of radi onuclides d efi n e d as " in s ign ificant"

2. Rev i sed survey uni t c lass ifica ti o n due to DRP detect io n

3. D e t ect io n of DRP s an d th e p ot e n tia l d ose co n se qu e n ces In so do in g, Zio nSol ut ions rev iewe d th e in it ia l d e t ermin at io n s t h at n o n e of th ese activ it ies requir e d a ch an ge to th e L TP. U p a n fu r th er rev iew, Z ionSol utions h as reaffirme d th a t th e first two activ ities listed a b ove di d n ot re qui re a ch a n ge t o t h e LTP ; h owever, th e th ird ac ti v ity, th e

Page 18 of 96 ZionSolutions, LLC ZS - 2022-010 Attachment detection ofDRPs, was found to require a change to the LTP. Detailed findings and the proposed changes to the L TP are de scribed b e low.

Results of the Activity Review

1. Activities that do not require a change to the LTP T h e first two act ivities identified above do not require changes to the L TP as described be low. As those activities did not result in a change to the L TP, an L TP eva lu ation, to address the 13 criteria in ZNPS License Co nditi on 2.C.(17), was not required. T h ose criteria apply when a ZNPS activity resu lts in a change to the LTP. The criteria are used to determine if the changes to the L TP require prior NRC approval.

A. Detection of Radionuclide s Defined as In s ignificant ZionSolutions performed a review of the preliminary results of the April 2021 inspection survey to determine if a revision to L TP Table 5-2 was necessary.

Specifica ll y, ZionSolutions evaluated the need to include radion uclid es that previously had been defined as " insignificant " in the table. Section 5. J of t h e L TP states that for a ll samp les a nal yzed for the fu ll su it e ofradionuc lid es (LTP Table 5-1),

the actua l in s ignificant co ntribut or ( I C) dose wi ll be calculated for each individual samp le result. If the IC dos e calculated is less than the IC dose ass igned for D CGL adjustment (2.5 mrem /yr for soils), then no further act ion wi ll be taken. If the IC dose exceeds 10 percent, t he n the additio n a l radionuclides that were the cause of the IC dose excee din g 10 percent w ill be ad ded as addit ion a l ROC for that survey unit.

For all soi l samples a nal yze d for the full s uit e ofra di onuclides, the IC dose was less than 10 percent; therefore, th e positive identifications of Am - 2 41, Pu-238 /239, orNp-237 remained insignificant to the dose contribution. As described in the response to RAI-6a, the h ard-to -d etect (HTD) radionuclides identified in th e samples do n ot c hange the ROC list for di stribut ed radioactivity. However, a LAR will be s ubmi tted for NRC review and approva l to revise C h apter 6 of the LTP to includ e DRP RO Cs.

The origina l ROC list (for distributed radioactivity) for the Zion site does not need to be changed.

B. Revised Survey Unit Classification due to DRP Detection If a DRP was id entified in a survey unit, the survey uni t classification was changed,

as necessary. A revision to a survey unit c lassification would not require a change to the LTP unless the survey un it was reclassified to a less restrictive classification.

During decommissioning, most DRPs were fou nd in C lass l s urvey units and therefore, no c h anges to the class ifi cat ion s were necessary. In so m e cases, DRPs were id entified in C lass 3 survey uni ts (e.g., s urvey unit 10 214) ; portions of those s urvey units were reclassified as C lass 1. As Z ionSolutions ha s not revised a class ifi cation to a less restrictive designation, no c han ges to the L TP are necessary.

Page 19 of 96 ZionSolutions, LLC ZS-2022-010 Attachment

2. Activity that requires a change to the LTP ZionSolutions originally conc lud ed that the detection of DRP s did not require a revi s ion t o the LTP. However, upon further cons id eration, ZionSolutions ha s concluded that a change to the L TP is necessary to describe th e process for det ectin g a nd calculat in g the dose from DRPs. The process for calculating the dose from DRPs i s fundamentally different from calculating the dose usin g DCGL s to demon strate compliance.

Detection of DRPs and the Potential Dose Consequences ZionSolutions initiall y determined that a change to the LTP due to the id e ntification of DRP s and the potential dose consequences of the DRP s was not required because DRP s are a sep arate so urc e term that is removed fr o m the s it e up o n detection. As s uch, th e re wo uld be no res idual DRP radioacti v ity to be eva luated in the LTP (i.e., no pathwa y for dose needed to be modeled and there was no need to revise DCGLs). 1n that regard,

finding a DRP is no different than finding a soil sample with concentrations in excess of the Ba se Case DCGL. In b oth in stances, Section 5.2. 14 of the LTP requires the mat er ial to be remediated. Each time a DRP was discovered, the DRP was removed from the surve y unit. Therefore, n o chan ge to the DCGL s was required and no change to the methodolo gy for calculating do se was required.

L TP, Chapter 5 Upon further consideration, ZionSolutions has conc lud ed that because the survey methodol ogy of the DRP Survey Plan to detect DRPs is different from the s urvey technique s de sc ribed in the L TP, a revision to the L TP is necessar y. ZionSolutions propo ses to revise the L TP by in corporat in g a new section into Chapter 5 entit led,

"S urve y Considerations for Suspected Discrete Radioactive Particle Areas." The n ew section will discus s the definition of a DRP and the need for special survey tec hniqu es and actions to be used specifically for the detecti o n of DRP s.

ZionSolutions will s ubmit the revi sed L TP Chapter 5 with a LAR to the NRC.

LTP, Chapter 6 Because it i s hy pothetically possible that DRP s cou ld be left at the s ite, and because th e dose for DRPs is calculated differentl y than the dose calculated to demon stra te compliance u s in g DCGL s, a change to C hapter 6 is nece ssary.

ZionSolutions will demonstrate compliance with the dose criteria in Part 20 Appendix E.

The propo se d change will s uppl ement how ZionSolutions dem o n strate s compliance with the do se criteria by also cons id ering the ri s k of dose from a DRP that ma y h y potheticall y be left on the s ite. This risk-based approach is in accordance w ith the guidance contained in NUREG-1757.

Page 20 of96 ZionSolufions, LLC ZS-2022-0 I 0 Attachment The DRP exposure sce nario will be eva lu ated as a less likel y but plau s ible (LLBP) scenario due to the low probability of DRP exposure occurring. ln accordance with Section 5.5.2 ofNUREG-1757,9 an LLBP is u se d to "... better ri s k in form the decision "

and to en ure that "... unacceptabl y hi g h ri s k s would not re s ult. " This is consistent with the approach appro ve d in the Z io n L TP fo r as es ing th e low-probabilit y ce nari o of the well driller contacting the Auxiliary Building drain s, which was also de sig nated as an LLBP sce nari o. ZionSolutions' approach is to demonstrate that the risk from the hy poth et icall y remainin g DRP s is not unacceptabl y high. Co n siste nt with the designati o n as an LLBP exposure sce nari o, th e dose from hy pothetical DRP s will n ot be added to the Zion s ite boundary d ose for dem o ns trating compliance with l O CFR 20 Subpart E.

ZionSolutions propo ses to revi se th e L TP by in corpo rating a new attachment into Chapter 6 entit led, " Less L ik ely but Plau s ible Scenario for Expos ure to H y pothetical Discrete Radioactive Particles. " The new attachment wil l di sc u ss the assessment of DRP do se and risk as an LLBP scenario, DRP exposure probability, a nd the meth o dology u sed to calculate inge s ti o n, inhalation, and s kin exposure do se from DRPs in o rder to demon strate that the ri s k from encountering a DRP is not unacceptabl y hi g h.

Additionally, the criteria for determining that " unacceptabl y hi g h risks would not re s ult "

from the LLBP DRP exposure scenario will be provided.

The LTP C hapter 6 revision w ill a lso address radionuc lid es of concern and mixes specific to DRPs.

ZionSolutions will s ubmit the revi sed LTP C hapter 6 with a LAR to th e NRC.

L TP Change Criteria (AD-11)

ZionSolutions ha s e aluated thi s activity against the change conditions in Attachment E-1 of procedure AD-11 and concluded that it requires prior NRC approval. As such, the proposed changes to LTP, C hapt ers 5 and 6, will be the basis of a LAR. Our conclusion is based on o ur reading of change criterion 9:

Change the approach used to d e m o nstrate comp li ance with the dose criteria (e.g., change from demon stratin g compliance u s ing derived concentration levels to demon s trating compliance us ing a dose assessment that is based on final concentration data)?

The technical bas is for the proposed changes to Chapters 5 and 6 of the L TP are de sc ribed in detail in our response to RAI-10.

9 NUREG-1757, Vol. 2, R ev. 2, Draft, " Co n so lidat ed Decommi ss ioning Guidance - C haracte ri zation, S urve y, and Determination of R a di o lo g ical C rit eria," Section 5.5.2, Eva luati o n C riteria for Decommissioning Groups 4 - 5 (Unrestric ted R e lea se Us ing Site-Specific Informati o n), p. 5-20, September 2020.

Pa ge 21 of 96 ZionSolutions, LLC ZS-2022-010 Attachment

NRC RAI-2b:

Ple ase discuss the results of the evaluation as they impact the ZNPS licensing basis. If an outcome of the process was that the licensing basis is not impacted, please justify why thi s is the case wh en considerin g the information available.

ZIONSOLUT/ONS R ES PO NSE:

As described in the response to RAI-2a, ZionSolutions has concluded that t h e methodo logie s to detect DRPs and to ca lc ul ate the potential dose from DRPs hypothetically remaining at the site constitute a c h ange to th e ZNPS li censing basis. Specifically, proposed changes to the ZNPS LTP, C hapters 5 and 6, are being submitted to the NRC in a LAR for approval.

NRC Additional NRC Comment, p. 12:

"G ive n the current information on final site radiological status, more information is necessar y in order for the NRC staff to reach a determination that the Zion site meets the L TP bounding assumptions."

ZIONSOLUTIONS RESPONSE:

ZionSolutions believes the term " bounding ass ump tions " to be equivalent to " li cense cond it ions "

within the context of this RAJ. In this sense, Zio nSolutions believes that th e responses to RAI-2a and RAI -2b have adeq uate ly prov id ed the additio n a l information necessary for NRC to reac h a determination that the Z ion site w ill m eet the LTP bounding ass um ptions fo ll owing revisions as proposed in the LAR.

NRC RAI-3a:

Please explain whether the Zion L TP considered or addressed these radionuclides.

ZIONSOLUTIONS RESPONSE:

Transuranics, including Am-241 and Pu-239, were evaluated as part of the LTP deve lopment and were identified in the initial radionuc lid e list as stated in Section 2.3.2 of the LTP. During the final deve lopment of t he ROC li st and t he IC radionuclide list, several rad ionuclides were evaluated to be in the IC li st including the trans u ranic radio nu c lid es. The development of the ROC and IC li sts is detailed within TSD 11-001, " Potential R adionuclides of Concern During the

Page 22 of96 ZionSolutions, LLC ZS -2022 -0 I 0 Attachment D ecom mi ss io nin g of the Zion Station," 10 TSD 14-019, " Radionuclides of Co nc ern for Soil and Ba se ment F i 11 Model Source Te rms," 11 and captured in the L TP.

However, th e site ' s ROC and IC list s are based on characterization d ata for di s tributed contam in at io n in so il, radioactive wa s t e, sy ste m s, s tructures, a nd compo ne nt s, a nd n ot DRP s. A LAR w ill be s ubmitt ed t o the NRC s taff for review a nd approva l that w ill in c lud e separa te cr iter ia fo r DRP s a nd the specific radionuclides.

NRC RAI-3b:

Please provide additiona l information on the background leve ls of Am-241 and Pu-239 that might be attributable to fallout in the local area surrounding t h e Zion site. Alternatively, please provide an explanation for the prese n ce of Am-241 and Pu-239 in the soils if these radionuclides are not attributable to fallout in the local area.

ZIONSOLUTIONS RESPONSE:

Backgro und radionuc lides at Zio n were evaluated as d oc umented in TSD 13-004, " Exa mination of Cs -1 3 7 Global Fa ll o ut in Soils at Zion Station." 12 This TSD contains informati o n on the producti o n of Cs -1 3 7 and Pu-239 /240 in weapons testin g and note s that th e activity ratio of Pu-239 to Cs-137 in weapons te s ting is 1/86.

The TS D also contains information on Cs-137 (F ig ure 3) and Pu-239 /240 (F ig ur e 4) depo s iti o n s by co unty in the U nited States. From thi s, the TSD concludes that the Cs -1 3 7 from fallout is 50 tim es higher than the Pu-2 39/240 depo sitions from fallout in the Zion area.

As part of the back gro und assess ment, a total of 64 sample s were s ubmitted to an off-site lab ora tor y for analysis. Each so il sample was analyzed for gamma-emitting nuclides by gamma spectrosco p y. The off-s ite lab orato ry analysis included Co-60, Cs-137, Sr-90, thorium isotopic (T h 22 8, Th-230, and Th-232), a nd uranium iso t opic (U-234, U - 23S, a nd U - 23 8).

From the so il sam pl e analysis, the hi g he st Cs -1 3 7 re s ult reported in TSD 13-004 was 1. 14 p Ci /g.

Us in g the expected activity ratio of Cs-137 to Pu-239 of 50, the estimated expected concentration of Pu-239 would be 2.82 E -02 pCi /g. This is well bel ow the nominal detection se n s iti v iti es for Pu-239 of approximately 0.1 to l pCi /g. T her efore, any positive detections of tran s uranic radionuclides in so il wou ld be considered plant-related rather than from fallout contributions.

10 ZionS o fution s TSD 11-00 I, "Potential R adi o nu clides of Co ncern During the Decommissioning of the Zion Station," R evi s ion 1, Octo ber 201 2.

11 ZionS o lut ion s TSD 14-019, "R adi o nuclid es of Co nce rn for Soil a nd B ase m ent Fi ll Mo de l So ur ce Te rm s,"

Revi s ion 2, Feb ru ary 2017.

12 TSD 13-004, " Exami n at io n of Cs-137 G lob a l Fallout in Soils at Zio n Station," Revision 0, May 20 13.

Page 23 of96 ZionSolutions, LLC ZS-2022 -01 0 Attachme n t The respo n ses to RAI-Ja a nd RAJ-le d escri be the lik ely orig in s of particles o n-site, based primarily up o n the radionuclide p rofi le of eac h.

NRC RAI-3c:

Compare background radiation le ve ls t o the le ve ls that were identified in the soil sam ples collected during the April 2021 inspection survey, and provide an explanation of whether the Am -241 and Pu-2 39 id e ntified in these samp les is the result of lic ensed material or background radioactivity from fallout.

ZIONSOLUTIONS RESPONSE:

ZionSolution s considers the Am-241 and Pu-239 id entified in these samp les to be the result of li censed material. As discussed above in the response to RAI-3b, the Am -24 1 and Pu-239 co ncentrat ions are sig nifi cantly hi g h er than those fo un d in background. A dditi ona ll y, the re s pon se s to RAI-1 a and RAI -1 c describe the lik e ly origins of particl es on-s ite, ba sed primarily upon the radionuc l ide profile of each.

NRC RAI-4a:

The ZNPS CRs indicated a " yes"' under the " 50.75(g) Issue" field. Please describe the factors that go into deciding whether an event is added to the Zion l 0 CFR 50.75 (g) file if it is indicated with a "y es " in an associated condition report. Please describe the factors that go into deciding whether contamination events are discussed in the site characterization portion of the L TP,

and/or subsequently used to update survey plans.

ZIONSOLUTIONS RESPONSE:

A " yes " was indicated und er the " 50.7 5(g) Issue " field for the r e levant C R s to indicate that the C /LT Ma n ager needed to eva lu ate th e potential n eed for an update to the 10 CFR 50.7 5(g) file as a result of the contami nati on eve nt. Sec ti on 7.2. 1 of AD -8, " Co rrective Act i on Program" 13 (include d in the enclosu re to this response) states:

If the event invo lves the sp ill or detection of radiologica l contaminat ion around the facility, equ ipm ent or s ite, or involves encountering un expected buried plant systems or components, notify the FSS manager of the potential for 10 CFR 50.75(g) considerations. Code the CR as " 10 CFR 50.75g " (for al l areas outside the ISFSI boundary) or " 10 CF R 72.30d " (for all areas inside the ISFSI boundary).

13 Zi o nSo luti ons AD-8, "C orrective Action Program," Revision 12, November 20 20.

Page 24 of96 ZionSolutions, LLC ZS-2022 -0 l 0 Attach m ent Accordi n g to the procedure, t he p os iti ve indi cat io n of "50. 75(g) Issue " acts as a trigge r for C/L T management actio n a nd no t as a s tatem ent of the ex iste nce of a d oc um e nted upd ate to the 10 CFR 50. 75 (g) file. Upo n th e co nc lu s ion ofC /LT man ageme nt 's cons id erat io n, a n update to the 10 CF R 50.75(g) file wo uld be made if s ig nifi ca nt co nt am inati o n remai n e d after a n y c leanup procedures o r there is rea so nable lik e lih ood that contaminants m ay ha ve pread to inacces s ible areas.

The part ic le relea se events were not included in the 10 CF R 50.75(g) fi le. Section 5. 1.1 of Z -

RP-104-001-003, " JO CF R 50.75(G) a n d 10 CFR 72.30(D) D oc um entatio n Requirements " 14

( in cluded in the enc los ur e to this response) states:

Document a record of each spill or o ther unu s ual occ urr e n ce involving the s pread of co n taminat io n (subject to th e scope of thi s proced ur e) in and aro und the site, o n Attac hm ent 1, R ecord for 10 CFR 50.75(g) or 10 CF R 72.30(d). T h ese records m ay be limited to in sta nces w he n sig nifi ca nt conta minati on rema in s after a n y c lea nup procedures or there i s reasonab le li kelihood that contami n a nt s m ay ha ve spread to inaccessible areas.

Because the particle co ntamin atio n was thought t o be successfu ll y clea n ed up a nd n ot spread to in access ible areas, n o updat es to the 10 CFR 5 0.7 5(g) file were mad e.

ln for mation o n rad ioac ti ve particles identi fied by the li censee thr o ug ho ut d eco mmi ss ionin g as we ll as during the Apr il 2 0 2 1 in specti o n su rvey does not indicate a need to upd ate or revise the process for including in formatio n in the 10 CF R 50.75(g) file. The fi le wo uld b e updated o nl y w h en s ig nifi cant contam in at io n remains after a n y cleanup proc edures or there is reasonable lik e lih oo d th a t contaminants may hav e sp read to inac cessib le areas. Nei th e r of these cases app li es.

The inputs to C h apter 2 of the Z io n LTP were the Historical Site Assess m e nt ( hi stor ical contami nation eve nt s) a nd ini tia l s ite characterizat ion. Rad io logica l c h arac teri zat io n data co ll ecte d after L TP s ubmitt a l we re u se d to verify the proper cla ssificatio n of survey units and to upd ate sampl e plans.

NRC RAI-4b:

Considering that the majority of the site characterization activities took place prior to 2014,

discuss why the site characterization discu ssion in the Zion L TP was not revised by the licen see to reflect the change in radiological conditions at the site that was determined in 2016, prior to the Zion LTP being approved in 2018.

14 ZionSolutions ZS'-RP-104-001-003, " 10 CFR 50.75(G) and 10 CFR 72.30(0) Documentation Req uirements,"

Revision 2, ovember 20 19 Page 25 of 96 Z ionSo lution s, LLC ZS - 2022 -010 Attac hm e nt ZIONSOLUTIONS RESPONSE:

T h e eve nt s we r e n o t in c lud e d in th e c harac ter iza ti o n rep o rt o r th e ini t ia l L TP b eca u se a de c is io n was m a d e n o t t o m o di fy e ith er th e ch arac teriza ti o n rep ort o r th e L TP w ith r es ult s fro m co ntinu in g c haracter izat io n or c h a ng in g radio log ica l cond iti o n s a t the site. In disc u ss io n s with th e N R C d urin g the LTP s u bm itta l p rocess, it was agreed t h a t co nti nui ng c h aracte r iza ti o n resu lts wo ul d b e prese nt ed in th e re leva nt FSS re lease reco rd s. S urvey uni t c lass ifi ca ti o n s we re c h a n ge d from th ose presented d ur ing initia l s ite characte ri za ti o n as warra n ted whe n p art ic les we r e d iscove re d.

As state d in th e res p o n ses t o RA I-2a a nd RA l-2 b, Z io nSolu tio ns h as co nclud e d th at th e m e th o d o log ies to detec t D RPs a nd to ca lcul ate th e p o tent ia l d ose from D RP s hypot he ti ca ll y re m a inin g at th e s ite co n s ti t ute a c h a nge to t h e ZNPS li ce n s in g bas is. T h ese c h a nges t o th e ZNPS li censi ng bas is w ill be impl e m ente d v ia m o di fica ti o n s to C h apters 5 a nd 6 of th e LT P a nd a LAR w ill be submit te d t o th e NR C.

NRC RAI-5a:

If not previously discussed in response to RAI-1, please provide information that explains the source of this particle and how it came to be present in SU 12203A.

ZIONSOLUTIONS RESPONSE:

L ik e ly particl e o ri g in s a r e di sc u sse d in th e res p o n ses t o RA I-la a nd RA I-lc. T h e lik e ly s our ce of th e p a rticl e di scove re d b y ORI SE in s urvey unit 122 0 3A is re act o r fu e l. As di sc u sse d in th e res p o n se t o RAI-1 c, once int ro duced into th e e nv ironm e nt, th e likel y tr ansport ati o n pathwa ys fo r p ar t ic les are sur face w ate r fl ow (run off durin g hea vy ra in s) and /or h eavy e quipm e nt and ve hicl e m ove m ent.

NRC RAI-5b:

Explain why the particle not being found during the licensee's FSS of SU 12203A does not indicate overall quality issues with the Zion FSS methodology, given that the particle contained gamma emitting radionuclides at levels that were within the scope and detection capabilities of the Zion FSS design.

ZIONSOLUTIO N S RESPONSE:

T h e d es ig n e d FSS d et ec ti o n sca n c apabili t ies ar e fo r di str ibut e d co ntamin a ti o n, n ot fo r p articl es.

T h e fa ilur e t o d e tect gamm a - emittin g rad io nuclid es o n p arti c les at leve ls th at we r e w ithin th e sco p e and d e tect io n c ap a bili t ies of th e or ig in a l FS S d esig n d oes not in a nd of itse lf indi cate a qu a li ty iss ue, e ith e r w ith th e met h o d o logy o r t he exec uti o n of th e FSS. A lth o u g h parti c les are w ithin th e d e t ec ti o n cap a bilit ies o f th e in strum e nt s, th e d etec ti o n of th e p a rti c le s was n o t w ithin th e sco p e of th e FSS d es ig n. If durin g th e p e rfo rm anc e of th e F SS a part icl e was d et e cted, it was Page 26 of 96 ZionSolutions, LLC ZS-2022 -0 l 0 Attachment removed. Separate efficiency vers u s di stance factors and detection capab iliti es would h ave to be calculated for particles because th ey represent a very different geometry, a nd the detector sensitivity var ies w ith the scan rate, the probe sw in g rate, and the distance between a particle and the detector. The DRP Survey Plan was im pleme nt ed to spec ifi ca ll y look for and remediate particles.

ZionSolutions will use the DQO process to address detection of DRP s given the potent ia l for them to be present. Thus, particle point source detection efficiencies and lic ense termination criteria should not be conflated with DCGL EMCS t hat are based on distributed contamination averaged over an area.

To address DRP detect ion during sca nning, the ZionSolutions p lanning team used the DQO process, w hi ch is desc rib ed in the DRP Survey Plan.

NRC RAI-Sc:

Explain why the s urro ga te ratio for Sr-90 /Cs-13 7 is different for thi s particle than that which was assumed for soils across the site, and as described in the Zion L TP.

ZIONSOLUTIONS RESPONSE:

The surroga t e ratio for Sr-90 /Cs -1 37 for the particle found in survey unit 12203A app li es t o fuel particles, n ot di str ibuted contami nati on. When the site character ization was performed, o nl y Co-60 and Cs-13 7 were detected in soi l samp les. The surrogate ratio was based upon distributed contaminat ion estimated from concentrations in A u xi li ary Building concrete samples obtained during c h aracter izatio n. A surrogate ratio sho uld n ot be based o n a sing le samp le analys is because the overall uncertainty to oth er samp les is high.

NRC RAI-Sd:

Evaluate the potential impact on the Sr-90 surrogate ratio assumed for SU 12203A due to the presence of this particle. Assess whether, in accordance with the Zion L TP, a survey unit specific surrogate ratio should be applied to this survey unit.

ZIONSOLUTIONS RESPONSE:

A survey unit -specific surrogate rat io does not need to be app li ed to this s urvey unit because if particle S0126 was found during the FSS, it wo uld have been removed. The survey unit surrogate relationships app ly to distributed radioactivity and require that the DCGLs be a ppli ed.

If the rad ionuclides were detected as di strib ut ed act ivity and on ly gamma spectrometry was performed, the LTP s urro gate Sr-90/Cs-137 of 0.002 would have been app li ed. However, only one part icl e containing Cs-137 and Sr-90 was identified, and this is not representative of distributed contamination. Lastly, a s urr ogate ratio should not be based on a single samp le analysis becau se the overall uncertainty to other samples is high. Based on the forgoing anal ys is,

Page 27 of 96 ZionSolutions, LLC ZS-2022-010 Attachment ZionSolutions believes that a survey unit-specific surrogate ratio doe s not apply due to the presence of particles.

NRC RAI-5e:

Evaluate the potential impact on the Sr-90 surrogate ratio assumed for other Zion survey units that may contain s imilar particles, and explain why the surrogate ratio applied to these other survey units is still valid. Provide a discussion to s upport reasonable assura nce that particles containing a simi lar ratio of Sr-90 to Cs-13 7 do not exist in location s outside of what the licen se considers to be the affected area.

ZIONSOLUTJONS RESPONSE:

The potential impact of the Sr-90 surro gate ratios assumed for other Zion su rvey units that may contain sim il ar particles has been d escribed in the response to RAI-5d. To provide a reasonable assurance that particle s containing a s imil ar ratio of Sr-90 to Cs-13 7 do not exist in location s o utside of the affected area, a compre hensive DRP Survey Plan (including sampling) ha s been implemented. There was high confidence that DRPs were not in areas not included in the scope of the DRP Survey Plan, as explained in the response to RAI-lg.

NRC RAI-5f:

Provide the potential overall or compliance dose consequences of assuming a different Sr-90 to Cs-137 surrogate ratio within what the license considers to be the affected area.

ZIONSOLUTIONS RESPONSE:

The potential dose consequences fro m assuming a different Sr-90 /Cs - 137 (e.g., greater than 0.002) w it hin the affected area wou ld result in a hi gher dose estimate. But, as noted in the response to RAI-5c, the surrogate ratios that were previou s ly determined from character ization data are app li cable to distributed residual radioactivity and not DRPs. To determine such a relationship, DRP DCGLs and a corresponding dose model would need to be established.

Therefore, using a Sr -90/Cs-137 rat io from a fuel particle for potential dose conseque n ces for di strib uted contamination in soi l in affected areas is not appropriate.

NRC RAI-6a:

Evaluate the potential dose contributions from the radionuclides that were defined as

" in sig nificant " radionuclides in the Zion L TP, using the range of ratios /radionuclides observed in the sa mples collected during the April 2021 inspection survey.

Page 28 of96 ZionSolutions, LLC ZS-2022-010 Attachment ZIONSOLUTIONS RESPONSE:

For the fuel DRP, the dose contributions from all radionuclides ha ve been includ ed. For the Co-60 particles, the dose calculations conservatively used a ll radionuclides estimated to be present in the reactor internals co mp onents. In the se calcu lat ions, we provided the contribution from all radion uclid es in c ludin g th ose identified as in s ign ifi cant in the LTP. These dose calculation re s ult s wi ll be includ e d in the LAR for C h apte r 6 of the LTP. The details of these calculations are provided in Specific Consideration 36 ofRAI -10.

NRC RAI-6b:

Evaluate the ability of the survey methods used during the Zion FSS activities to detect the potentially significant radionuclides identified during the April 2021 inspection survey that were not on the original ROC list for the Zion site.

ZIONSOLUTIONS RESPONSE:

The scanning methods used during the Zion FSS activities are standard indu s try practice. If a particle is detected during scanning, that particle is rem ove d, regardless of radioisotopic content,

including isotope s considered insignificant. The ROC list for the Zion site identifie s radionuclides that comprise 90% or more of the do se even though other radionuclides are pre se nt at th e s ite. Those identified HTD radionuclides can only be detected by laborator y analyses of sample s. Based upon the re spon ses to RAI-3a and RAI-6a, the HTD radionuclides identified in the sa mple s do not change the ROC li st for di stributed radioactivity. However, a LAR will be submitted for NRC review and approval to revise Chapter 6 of the L TP to include DRP ROCs.

The original ROC list (for distributed radioactivity) for the Zion sit e does not need to be changed.

The mo st likel y cau se for why particle s o r other materi a ls were not identified during licensee s urveys is that the DQOs were not deve loped to detect particles. Nonetheless, ZionSolutions not es t hat 255 particles were identified and remediated during active decommis s ioning, and another 25 particle s were identifi e d and remediated durin g FSS or RAs, for a total of 280 particles discovered by ZionSolutions. The DQO s and s u rvey m eth odo log ie s were enhanced for the implementation of the DRP Survey Plan to provid e a high degr ee of confidence that no DRP s posing an unacceptably high risk remain on-site.

NRC RAI-6c:

Evaluate whether the observed conditions are within the bounds of what was assumed in the Zion L TP (i.e., 10% of the dose is from insignificant radionuclides) and what potential actions are needed (e.g., a license amendment to change the list of ROCs) if the final site conditions do not fall within the original assumptions used in the L TP.

Page 29 of96 ZionSolutions, LLC ZS-2022-010 Attachment ZIONSOLUTIONS RESPONSE:

As described above in the responses to RAI-6a and RAJ-6b, no action is needed to change the ROC list in the LTP for distributed contamination. ALAR will be s ubmitted to revise Chapter 6 of the L TP to se parately address ROC for DRP s.

NRC RAI - 7a:

Indicate how the current site conditions are consistent with the commitments in the Zion L TP given the surface materials noted during the NRC ' s April 2021 inspection survey.

ZIONSOLUTIONS RESPONSE:

The surface material s noted durin g the NRC 's April 2021 in spection s urvey are s imilar in appearance to CCDD that was previously stored and m ove d around the s ite. CCDD was s urveye d in accordance with regulatory guidance and approved procedures and was found to ha ve no detectable activity above back gro und (see the response to RAI-1 a from the February 10,

2021, submittal). The CCDD that was not placed into a ba se ment ha s bee n removed from the s ite. Any re s idual CCDD that was inadvert e ntly left o n the surface durin g removal is concrete that was determined to have no activity above background. Additionally, the survey units where the residual CCDD resides was subject to a 100 % gamma scan durin g FSS and the FSS passed in all cases. The satisfactory result s of FSS do not nece ss itate further removal of the CCDD. In accordance with the LTP, clean fill materi a l from an off-site so urce was used to fill the last 3 feet of each ba se ment up to the 591 feet elevation (i.e., grade). As such, ZionSolution s believes that the current site conditions are consistent with the commitments in the Zion LTP.

Sample S204AEu in survey unit 12201B from the April 202 1 inspection survey contains radi on uclide s consistent with neutron activation (e.g., E u-152, Eu-154), which is indicative of activated concrete originating from the containment bi os hield and not the containment exterior concrete (CCDD). A proce ss was in place to load potentially contaminated concrete into containers in a controlled fashion to limit the spread of contamination. As discussed in the responses to RAI-la and RAI-lc, the internal containment bioshield concrete was likely introduced into the so il durin g was te handlin g op erat ion s. This potential error in was te handlin g doe s not indicate a failure to follow commitments made in the L TP.

NRC RAI-7b:

Provide information on whether the material on the Zion site surface is demolition debris that should have been removed during decommissioning, offsite gravel that was used for grading, or some other explanation for its prese nce, such as basement fill that has been disturbed by action of weather ( e.g., erosion, freeze-thaw cycles) or site operations.

Page 30 of96 Z ionSolutions, LLC ZS -2022-010 Attachme n t Z I O NSOL U TIO N S RE S PO NSE:

D u ring d eco m m issio nin g a n d site res t orat io n, Z io nSolutions a tt e m pted to e n s u re that d e m o lition d ebris was removed. T h e in format io n th at Z ionSo l utions prov id ed follow in g th e May 20, 2021, te leconfere nce descr ibes ZionSolutions ' best effo r t to docume n t th e posit io n t hat every effort was put forth towards c lea nin g up as m uch demolition and concrete debri s at t he ite a s reaso n ab le.

Upon further review, ZionSolutions d oes not be lieve that deb ris identified is fi ll mater ia l brought to the s u rface by freeze - thaw cycles or erosio n. Wh ile conceivab le, the freeze-thaw sce n ar io is un likely because sand was used as the m ajority of t he surface fi ll mater ia l for th e power bl ock area to re pl ace t he sacr ific ia l layer th at was re m e di ated.

While Z ionSolutions ca nn ot prec ise ly explain t he sou rce of concrete debr is or debris -li ke m ater ia l, Z io nSolutions h as ide nt ifie d th e fo ll ow in g as the most li ke ly so urces for t h e m ate ri a l th at was o bserved.

W a s t e H a ndling Op e r a tion s. It is poss ib le t h at o n rare occasio n s, m in ima l co n crete was introd uced in to th e enviro nm e nt d ur ing waste ha nd lin g operatio n s. Recent wa lk - downs revea le d m inim a l in sta nces of id e nt ifie d po t e ntia l de m o li t io n de b r is. In o rder t o e n s ure th at a ny activ ity res ul ti n g fr om waste h a ndlin g h as b ee n re m ed iate d, s ur vey unit s w he re ra ilc ars we r e load e d and prepar e d fo r s hipm e nt were s ur veyed as p art of th e DRP S u rvey P lan. Addit io n a ll y, when CC DD was re m oved from t h e six survey un its (12203A, 122 0 3B, l 2203C, 12203 D, 12 11 2, 12 11 3) w h ere it was t em pora ril y s t o re d or tran sp or te d th ro u g h a n d t he five s urvey units w h ere it was store d lo n g-term (1 22 0 5A, l 22 0 5B,

12205C, 12205 D, 12205E), r es idu a l CC DD m ay h ave inad verte ntl y b ee n left be hind. In th ese eleve n s urvey uni ts, FSS has b ee n repe r forme d.

Non-Concrete Material Was Mi s identified. Las tl y, it is poss ibl e th a t th e co n c re te o bserve d by ORI SE an d t h e N R C was actu a ll y sand st o n e grave l, u se d fo r roa d w ays, w hi c h can be mi sta k en for sm a ll co ncrete c hun ks. A dditi o n a ll y, c lea n fi ll so il fr o m th e Z io n land fi ll th at was u se d fo r th e to p 3 fee t of b ase m en ts an d to fi ll excavat io n s was clay -li ke. W h e n thi s c lay -lik e m ateria l is dr ie d, h ar d en e d, an d s ub se qu e n t ly di sturb ed, it can resemb le s m a ll conc r et e c hun ks. T hi s m ater ia l was su rveyed p r io r to being imp ort ed on-site and was a lso subject t o sca nn in g durin g FSS.

NRC RAJ-Sa:

Di scu ss the final s ite configuration for the Zion site area s that received a sacrificial layer of soil that was subsequently removed and remediated, and over which clean fill material was emplaced. Specif y the thickness of the clean cover material intended for the end state over these areas, and from where the clean cover material was sourced. Indicate the survey units where this final s ite configuration exists.

Page 31 of 96 ZionSolutions, LLC ZS - 2022 -010 Attac hment ZIONSOLUTIONS RESPONSE:

Pri or to th e d e m o liti o n of th e U nit 1 and U nit 2 Co ntainm e nt Buildin gs, an approximate 1.5 feet la yer of sacrificial so il was placed in the areas identified in F igure 3 below. The sacr ificial layer wa s co mpri sed of th e c lay -li ke material from the Z io n la ndfill. After demolition of the C o ntainment Building s, the sacr ifi c ia l la y er wa s removed in its e nti ret y and any s oi l beneath the sacrific ia l layer that h a d re s idual radioactivity a bove the OpDCGL was remediated as necessar y.

This re m ediation p o tentiall y to ok so il awa y from the minimum 3-fo o t thick fill la y ers wit hin the footpri nt of previously-backfilled s tructur e s.

A large-s cale RA was performed over the entire power block area, and the results we re previously presented in th e Feb ruar y 10, 202 1, s ubmitt al (" P ower Block RA Report Attachments " ). In ord e r to bring these a rea s back t o gra d e level, in the in s tan ce that re mediati o n n ecess itated the removal of soi l be low gra d e, sa nd was bro ught o n-s ite from th e A nti oc h quarr y.

The thickness of the clean cover material intended for the end state ove r the se areas is 3 feet.

The s urvey unit s tha t we re impa c ted by the sac rificial layer of soil a nd s ub sequent p ote nti a l remediation are as fo llow s : 1020 3F, 12201 A, 12201B, 12201C, 12202 A, 1220 2 B, 12202C,

12202 D, 12202 E, 122 0 2F, 12104, 12105, 12 106, 12107, 12108, 12109, 12110, 12111.

Page 32 of 96 ZionSolutions, LLC ZS-2022 -0 l 0 Attachment

Figure 3-Sacrificia l Soil Boundary

64 1928.10 343603.37

~. :

rrrrrrr,,

0 II IO 31 1.1at9rt Legend Sacrifiial Soil NADBJ IL Sista Plane East 1201 (Meters}

D Sacrificial So il Boundary 2011 Aerials Lake County GIS Dept.

Date Modified: 02 /12 /20 19

Points to be GPS 'ed Sacrifical Soil

Page 33 of96 ZionSolutions, LLC ZS-2022-010 Attachment NRC RAI-8b:

For the areas of the site directly above backfilled basement structures (including the ZNPS Crib House basement in SU 12204), verify that the thickness of the clean cover material between the land surface and the upper level of the basement fill material is consistent with the Zion L TP commitments and the description of the site end state in Phase 4 of the Zion FSSR.

ZIONSOLUTIONS RESPONSE:

The thickness of th e clean cover material between the la nd s urface and the upper level of the baseme nt fi ll material for the areas of the site directly above backfilled basement structures ha s b ee n reviewed and determined t o be consistent w ith the Zion LTP co mmitment s and the FSSR.

The methodolog y for this assessment is de sc ribed belo w.

All remaining structure basements were dem o lished to three feet bel ow grade level (588 feet elevation). As the demolition was comp leted for a g iven structure, a third-party s urveyor was b rought in to p erfor m an elevation s urvey. Locations for the elevation surve ys were ba se d on judgment, e.g., did the e levation appear higher than the surrounding area. Readings were collected and results were evaluated immediately. The contractor would be notified, as necessary, if any of the locations needed additiona l material remo ve d to meet the 588 feet maximum elevation. The as-left e levations for the basement structures were verified b y the third party surveyor prior to backfill.

The basements were backfilled using CCDD or c lean soil from the Zion landfill. The Zion landfill was tested and approved as an uncontaminated off-site soil source. The final three feet of fill from the 588 feet e levation up to grade (59 1 feet elevation) consisted of clean soil from the Zion landfill, or as noted in the re sponse to RAI-8a, sand from the Antioch quarr y. Fina l elevation measurements were performed after backfill to verify that the as-left soil e levation was at grade. Figure 4 and Figure 5 below show the as-left so il e levations for the pow e r block area.

As detailed in the response to RAI-lj, final site grading was completed on September 23, 2020.

After completion of final site grading, another e le vation survey was performed, the result of which is shown in Figure 6. ZionSolutions commits to confirming that final soil elevations are consistent w ith the LTP. If future observations reveal conditions incon s is tent with the assumptions mad e in the LTP, ZionSolutions commits to making any modification s necessary.

Page 34 of96 ZionSolutions, LLC ZS-2022 -010 Attachment Figure 4 - Unit 1 Area Grade Measurement Location s

SU12113

Final Grade Elevation Locations

Grade Locations 08/ 29/20 19 Drawing : Final Grade Locat1on1

Page 35 of96 ZionSolution s, LLC ZS-2022-0 l 0 Attac hment Fig u re 5 - Unit 2 Area Grade Measurement Locati on s

I I / I I I

I i I ! / I f !

! i/ I I i SU10203A j/ I I SU122018 i I SU12201A SU12201C I I SU12201D I

202A

~--.._,

U12202D SU1

Legend 12111 Final Grade Elevafion Locations

0 F'nal Gtade LOUtiona I Date* OW23/201i

o,awing: Anal Grade Locations

Page 36 of96 ZionSolutions, LLC ZS -2022 -010 Attachment Figure 6 - October 2020 Elevation Survey

_.,._,..._ OONtOJII

"""\\..,+,.,,.....Jlot

Sfi SHEET AS801

............... QWWWIOFW-.IUIICII _.,.,. - ZION SOLUTIONS 10 1 SHILOH BOULEVARD ZION, IL 60099 AS-$UILT GRADING PLAN

--- ASB02

Page 3 7 of 96 ZionSolutions, LLC ZS-2022-010 Attachment

NRC RAI-Sc:

Justify how current site conditions are consistent with Zion LTP. Jfthe Zion site condit ions are not consistent, discuss the intended path forward (e.g., a license amendment to revise t he assumptions in the Zion L TP) to resolve the inconsistency.

ZIONSOLUTIONS RESPONSE:

The following are the commitments to site conditions as detailed in the LTP:

All on-site building s, structures, and components must be demolished and removed to a depth of at least 3 feet below grade.

The structures are backfilled with CCDD or so il from an off-site so urce.

The Basement Fill Model applies to the backfilled basements which will have a minimum of three feet of cover and approximately 3 meters of clean fill above potential source term as defined by the equilibrium water level in the backfilled basements. The equilibrium water lev e l is conservatively assumed to be at the natural water table elevation of 579 foot. Therefore, the do se from the water-independent exposure pathways is negligible.

ZionSolutions is confident that the final site conditions are consistent with the LTP. It is possible that, because of the times at which structures were backfilled (earlier in the decommissioning process in some cases), a piece of concrete or debris on the surface could have been inadverte ntly deposited on the surface and forced to a lower depth into the top 3-foot layer of clean so il fill through the movement of heavy vehicles. The presence of a small piece of concrete within the 3 feet of cover is not significant and would not require a license amendment to revise the assumptions in the Zion L TP.

Elevation surveys, as detailed in the response to RAI-8b, were performed to verify that basement structures were no higher than the 588 feet elevation. Elevation surveys were performed after backfill to verify the as-left so il elevations were at grade (3 feet above basement structure).

Additionally, sectio n 6.6.1.1 of the LTP states, "For DUST-MS modeling, the initial source term in each basement is nominall y assumed to be 1 pCi/ m2 uniform activity over all walls and floor s urfaces below 588-foot elevation." Section 6.6.1.2 states, "To accommodate any future perforation plan s, and ensure conservatism, the mixing volume for the DUST-MS modeling is based on a ba semen t water elevation equal to the 579-foot elevation of surrounding groundwater." The model assumed all of the activity on walls above the 579-foot elevation is in stantly mixed with the water below the 579-foot elevation. Since there is no dose from walls in the unsaturated zone above the 579-foot elevation, a 3.6-meter cover was used in RESRAD.

(591 -579 = 12 feet= 3.6 m). Because the basement walls remain 3 feet below grade at the 588-foot elevation, and the grade is verified to be at the 591-foot elevation, the water-independent

Page 38 of96 ZionSolutions, LLC ZS-2022-010 Attachment dose pathways used to determine compliance with the dose criteria for unrestricted release remain unchanged.

NRC RAI-8d:

If the thickness of the clean cover material is less than that assumed in the Zion LTP, or the erosion rate is greater than what was assumed in the RESRAD dose modeling for the Zion site, provide an evaluation of the dose resulting from the material in the Zion basements structures with the lower amount of shielding/dilution.

ZIONSOLUTIONS RESPONSE:

As described above in the answers to 8a-c, the conditions at the site, including the thickness of the clean cover material, are as assumed in the Zion LTP. There has been no significant erosion since final site grading on September 23, 2020. Despite these circumstances, we have prepared the following analysis to demonstrate that even in the case of some future erosion, the depth of cover is adequate to provide for the health and safety of a hypothetical occupant.

The relative dose was calculated under three conditions to evaluate the effect of increased cover erosion rate and decreased cover thickness.

Condition 1: BFM RESRAD model as applied in the L TP

Condition 2: BFM RESRAD model with erosion rate increased to the 75 th percentile (2.92E-03 m /y) and cover thickness reduced by 0.5 m

Condition 3: BFM RESRAD model with erosion rate increased to the 75 th percentile (2.92E-03 m /y) and cover thickness reduced by 1.0 m The relative doses from the ROC under each condition were calculated using the following equation:

Equation 7 - Relative Dose

where RD = relative dose for ROC JA; = activity fraction for radionuclide i DSR; = dose to source ratio for radionuclide i (mrem /yr per pCi/g)

The ratio of relative doses from Condition 2/Condition I is 1.0 for both the Containment and Auxiliary mixtures. The ratio from Condition 3/Condition 1 is 1.10 for both mixtures. In summary, there is no change in dose when the cover thickness is reduced by 0.5 m. The dose is 10% higher when the cover is reduced by 1.0 m.

The relative dose results are provided in the three tables below :

Page 39 of96 ZionSolutions, LLC ZS-2022 -010 Attachment Tabl e 6 - R elati ve Dose LTP Radionuclide DSR Relative Dose LTP LTP Containment Mix Aux Mix H - 3 2.1 69E -0l l.619E-04 C o -60 1.122E-0l 5.291E-03 l.029E -03 Ni - 6 3 l.57 3E-0 2 4. 169 E-0 3 3. 729 E -03 Sr-90 4.362E+0l l. 188E-02 2.246E -0 2 C s -1 34 l.935E+00 l. 562E-04 l.954E-04 C s-137 1.536E + 00 1.047 E+ 00 1. l 57E+00 Eu-152 3.801E-02 l.672E - 04 E u-154 5.520E -02 3.230E-05 Sum l.07E + 00 1.18E+00

Table 7-R elati ve Dose 75th P er centil e E r osion and Cover Thicknes s R eduction of 1.0 m DSR Relative Dose Radionuclide 75th Percentile erosion Containment Mix Aux Mix 1 m cover reduction H-3 2.269E-01 l.69E-04 Co-60 2.064E-0l 9.73E-03 l.89E-03 Ni - 63 l.869E-02 4.95E-03 4.43E-03 Sr-90 4.670E + 0l l.27E-02 2.40E - 02 Cs-134 2.122E + 00 l.7 1E-04 2.14E -04 Cs-137 l.685 E+00 1.lSE+00 l.27E+00 Eu-152 3.833£ - 02 l.69E -04 Eu-154 5.575E - 02 3.26E -05 Sum 1.18E+00 l. 30E+00

Table 8 - R elati ve Dose 7511' Percentile Erosion and Cover Thickness Redu ction of 0.5 m DSR Relative Dose Radionuclide 75th Percentile erosion Containment Mix Aux Mix 0.5 m cover reduction H-3 2.169E-0l l.6 2E-04 Co - 60 1. l 25E -01 5.31E-03 1.03E-03 Ni - 63 1.574E-02 4. 17E-03 3.73E-03 Sr-90 4.384E + 0l 1.19E-02 2.26E-02 Cs-134 1.935E + 00 l.56E-04 l.95E-04 C s-137 1.536E + 00 l.0SE+00 1.16E + 00 Eu-152 3.7 97E - 02 l.67E-04 Eu -1 54 5.522E - 02 3.23E - 05 Sum l.07E+00 l.18E+00

The actua l erosion rate is less than what was ass um ed in the RESRAD dose modeling for the Zion site. One insta n ce of sign ifi ca nt eros ion was id entified in ES-ZION - CR-2020-0001 (included in the enc losure to this response), where the area so uth of the Forebay and Cribh ouse basement appeared to have eroded approximate ly 2 feet. This area was backfilled to the 591 foot e levation during final site gradi n g. T h ere are no v is ible sign s of erosion in this area or a ny other area above basements s in ce fina l s it e grading.

Page 40 of96 ZionSolutions, LLC ZS-2022-0 l 0 Attachment NRC RAI-9a:

Describe how any soil reuse aligns with the commitments in the Zion LTP.

ZIONSOLUTIONS RESPONSE:

Soi l was stockpiled and reu sed o nly to s upport buried pipe or other commodity removal. in each of these in sta nce s, an RA was performed us ing the m ethodology outlined in Section 5.7.1.7 of the L TP. Soil w as always reu se d in th e excavation from where it came (i.e., soil that originated from si te was never stoc kpiled and used as fill later on).

Soil reuse as performed during decommissioning a li gns with Section 5.7.1.7 of the LTP. The response to NRC RAI Question 8a from the February 2021 RAJ responses submittal is reiterated below.

Section 5.7.1.7 of the LTP states:

ZSRP will not stockpile and store excavated soil for reuse as backfill in basement s. However, overburden soils wi ll be created to expose buried components (e.g. concrete pads, buried pipe, buried conduit, etc.) that will be removed and disposed of as waste or to install a new buried system. In these cases, the overb urd en soi l w ill be removed, the component will be removed or installed, and the overburden soi l will be replaced back into the excavation. ln these cases, a RA will be performed. The footprint of the excavation, and areas adjacent to the excavation where the soil will be staged, will be scanned prior to the excavation. ln addition, periodic scans will be performed on the soil as it is excavated, and the exposed surfaces of the excavated soi l will be scanned after it is piled next to the excavation for reuse. Scanning will be performed in accordance with section 5.7.1.5.1. A soil sample will be acquired at any sca n location that indicate s activity in excess of 50% of the soil Operational DCGL.

Any soil confirmed as containing residual radioactivity at concentrations exceeding 50% of the so il Operational DCGL will not be used to backfill the excavation and will be disposed of as waste.

All radiological surveys performed to evaluate soils from the excavations of buried pipe, including the grade footprint of the excavation, the grade footprint of the overburden laydown area, the bottom and sidewalls of the excavation, and acceptability of the overburden to be used to eventually backfill the excavation were performed in accordance with Section 5. 7.1. 7 of the LTP. RAs were designed, evaluated, and documented in accordance with ZionSolutions procedure ZS-LT-200-001-001, " Radiological Assessments and Remedial Action Support

Page 41 of 96 Zio nSo l uti ons, LLC ZS - 2022 -0 I 0 Attachme nt S urve ys." 15 For all media sa mplin g per formed to eva lu ate excavat ion soi ls, the Op D CGLs for subsurface so il s fro m Table 5-8 of th e LTP we re us e d as the action leve l. The action le ve l for scanning was set at the MDCR of the in str um ent plu s background. The in stru m ent a nd d ata quality requirements spec ifi ed in procedure ZS -LT-200 -001-001 for the performance of an RA are th e s am e in strument a nd data q ua lit y re qu ir em e nt s required for the performance of FSS. The results of the RAs in these cases were provided t o NRC R eg ion Ill who, after review, provided co ncurrence t h at the excavat ions were suitab le for backfilling.

As o utlined abov e, soi l re use a li gns with the comm itments in the Zi o n LTP.

NRC RAI-9b:

Provide justification and documentation of the process used to determine soil reuse as appropriate, including radiological scans for any soils that were reused from other parts of the Zion site and describe how the process aligns with what was discussed in the RAI response associated with the Zion L TP review dated February 27, 2017 (ADAMS Accession No.

MLI 7208Al21).

ZIONSOLUTIONS RESPONSE:

The process u sed to det ermin e when so il m ay be r e-u sed o n s it e is detailed in Section 5.7.1.7 of the L TP, as is reiterated in the response t o RAI-9a. The soi l mu st b e surveye d und er an RA and shown to h ave radion u cl id e conce ntrati o ns below 50 % of the soi l OpDCGLs before it ca n be reused.

As state d in the res pon se to RAI-9a, so il s were excavate d a nd reu sed on ly to s upp ort buried pipe or other commodity removal. Spoils from a particular excavation were placed back into the same excavatio n (and not transported aro und the site to be used in a different locat io n) o n ce the criteria for reuse of the soi l was met as o utlin ed in the RA. The acceptabi li ty of t he so il to be reused as fill is determined by so il sa mpling and not sca n m eas ur e m e nt s. The criter ia for reuse of th e so il is that the co nc entratio n s in the so il are below 50% of the soi l OpDCGLs. A n y soil confi rmed as containing residual radioactivity at concentrations exceeding 50% of the so il OpDCGLs was not used to backfill the excavat io n a nd was disposed of as waste.

The RAI response associated w it h th e Z io n LTP rev iew dated February 2 7, 2017 (ADAMS Accessio n No. MLl 7208Al21) provided a basis of th e lang ua ge presented in Sectio n 5.7. 1.7 of the LTP and in ZS-LT-200-001-001.

The burie d pipe remova l RA res ult s are not di sc u sse d in the relevant re lease records, and as su c h the RA results were provided to the NRC in the e ncl osure to the February 2 0 21 RAI responses

15 ZionSo luti ons ZS-LT-200-001 -0 01, " Radiological Assessme nt s and Remedial Action Supp ort Surveys," Revision 6, May 2019.

Page 42 of 96 Z ionSolution s, LLC ZS - 2022- 01 0 Attac hm e nt s ubm itta l (a sprea d s hee t e nt itl e d " Buri e d Pip e RA R es ult s" ). T h e locat io n and timin g of c ir cum s tan ces w h e re so il reu se oc curr e d is p rov id e d in t he ab ove -m e n t io ned spread s heet and in th e res p o n se t o N R C R e qu es t 8a from th e Fe bru ar y 202 1 R A I res p o n ses s ubmitt a l. Radi o log ica l sca n data fo r so il s th a t we re re u se d (RA d ata) we re n ot di g ita ll y a rc hi ve d b efo re b e in g se nt to long - te rm reco rd s torage. s uc h, th e scan data a re not rea dil y avai lab le. ln li e u of sca n resu lt.

ZionSolutions has p rov id e d t hi s co mpr e h e n s ive sprea d s h eet that d eta il s t h e soi l sa mpl e res ult s

( i.e., co mpli a nce m eas ur e m e nt s to ve ri fy acce p ta bili ty as fill ) fro m every buri ed p ip e RA.

NRC Addit ion al NRC Comment, p. 34:

" These preliminary responses are not adequate for the NRC staff to verify that the reuse of e x cavated soil at the site is consistent with the commitments included in the Zion L TP."

ZIO SOL UTIO N S RESPO SE:

ZionSolutions wa nt s t o c lari fy th at it was not th e int e n t of th e p re li m in a ry res p o nse to s uggest th a t th e 3-foo t c lea n cove r stra tum a bove bac kfill e d s tru ctur es in c lu des n a ti ve so il o r re u se d so il.

T h e inte nt of th e p re limin a r y res p o nse was to d e m o n s t rate t h at th e co mmitm e nt t o h ave th e top 3 feet of eac h b ase m e nt s tructu re filled w ith c lea n so il fro m an off-s ite so urc e was m e t and th at that cr ite ri o n does not apply to th e enti re s ite, o nl y the foo tprint of ba ckfilled s tru c ture s.

Z ionSol ut ions wo uld lik e to re itera te th a t spo il s fro m a p arti c ul ar excavat io n for bu r ie d pip e or ot h er co mm o di ty re m ova l we re pl a c e d bac k into th e sa m e excava ti o n a nd no t t ra n sp o rte d a ro und th e site to b e u e d in a di ffere nt lo cati o n o n ce the c rit er ia fo r reu se of th e so il we re m e t a s o utlin e d in th e RA and in Sect io n 5.7. 1.7 of th e LT P.

NRC RAI-10 PATH FORWARD:

The licensee should demonstrate how its FSS meets IO CFR 20. 1402, or propose a revised survey plan specifically designed for detecting and removing discrete radioactive particles. Goal s of this survey would be to : (I) detect discrete radioactive particles ; (2) remediate detected discrete radioactive particles ; (3) determine the radionuclide composition and activity of the collected particles ; (4) estimate the number of discrete radioactive particles that may remain at the site after the survey is completed (i.e., discrete radioactive particles either missed or below the MDA) ; and (5) facilitate collection of information necessary (physical and chemical properties) to estimate the radiation dose from discrete radioactive particles that may remain at the Zion site after the survey is completed. In developing its survey plan, the licensee should consider the information provided below, in add iti on to other applicable resources, as it applies to the Zion facility. In this approach, it is expected that the licensee wou ld collect discrete radioactive particles that were detected during the survey, and then analyze them to better understand their characteristics and impact on the final site assumptions.

P age 43 of 96 ZionSolutio ns, LLC ZS - 2022 -0 l 0 Attach m e nt Due to the lack of specific NRC guidance on planning and conducting surveys for discrete radioactive particles at this time, the staff is providing the following information that the licensee may consider when developing its survey plan, if it chooses to develop a survey plan. Overall,

the licensee should consider using the Data Quality Objectives Process, as recommended in the existing NRC g uidance for planning decommissioning surveys. In additio n, the survey plan should take into account the results from the limited-scope NRC confirmatory conducted in April 202 1 and describe which portions of the site are to be surveyed, along with the rationale for any portions of the site not included in the survey. This rationale should consider information on the source and transport of the discrete radioactive particles provided in response to RAI-1 in the NRC letter dated August 19, 2021 (ADAMS Accession No. ML2 I 23 I A 187). Also, when de sign ing the s urvey plan and determinin g the MDA for discrete radioactive particle s, the licensee should consider the investigation levels that may require a change to the Zion L TP (i.e.,

ZNPS License Condition 2.C.(17) Criterion F).

ZIONSOLUTIONS OVERVIEW FOR RAI-10 ZionSolutions has designed and impl emented a revised survey plan, Survey Plan for Discrete Radioactive Particle Identification and Remediation, ZS -LT-07, Revision l (the "DRP Survey Plan"), spec ifi ca ll y for the purpose of d etecting a nd removi n g discrete rad ioact ive particles (DRPs). The DRP Survey Plan 16 is included as part of the ZionSolutions response to RAI-10.

The objective of the DRP Survey Plan is to identify and remediate all the DRPs identified. This will provide reasonable assurance that there wi ll be no DRPs remaining on the Zion site that could pose an un acceptab ly high risk to a member of the public. Based o n the completion of the survey a nd investigations, an estimate of the number and activity ofDRPs that may hypothetically remain h as been made and the dose and risk from the hypothetical DRPs has been estimate d.

ZionSolutions has performed an extens ive dose evaluation, described in detail in response to Specific Consideration 36, that eval u ates all potential effective doses and exposure pathways from particles with Co - 60 or Cs -1 37 activities exceed in g the 50 th percenti le a po teriori MDAs of the survey. This includes potential doses if the particles' physical or chemica l properties change over t im e. Cs-13 7 is used as a surrogate isotope for transuranics in spent fuel particles.

The DRP exposure scenario has been evaluated as a less likely but plausible (LLBP) scenario due to the low probability of DRP exposure occ urrin g. In accordance with Section 5.5.2 of NUREG -17 57, an LLBP is used to "... better ri sk inform the de cision " and to ensure that

16 References to the DRP Survey Plan also include the material described in the accompanying technica l support document (TSD), " Calibration and Discrete Radioactive Particle Detection Sensitivity and Performance Assessment for a Lud lum 44-10 Six-Detector Array," TSD 21-00 I, Revision 2.

Page 44 of 96 ZionSolutions, LLC ZS-2022-0 l 0 Attachme n t

"... unacceptabl y high ri s k s wo uld n ot result. " Z ionSolutions ' approach is to dem o n strate th at t he r isk fro m the h y p oth et ic a ll y remaining DRP s is not una cce ptabl y hi g h. Co n s istent w ith the d es ig nati o n as a n LLB P expos ure sce n ar io, the dose fr o m the hypothet ica l DRP s w ill n o t be added to th e Zion ite bo und ary d ose for demon stratin g co mpli an ce w ith 10 CFR 20 Subpart E.

The dose eva lu ation demon s trates th a t inge s ting a n irradiated fuel partic le w ith a n ac ti v it y cor res p o ndin g to the 50 th percenti le a po s terior i Cs -1 37 MDA wo ul d n o t re s ult in a n un accepta bl y hi gh risk. T h e dose from thi s hypo th et ica l particle wo uld be 59.0 mr e m (CEDE),

w hich is acceptable for a n LLBP sce n ar io. The u se of the 50 th percenti le a post e rior i MDA is reasonab le for an LLBP sce nari o. NUREG -17 57 Vol. 2, Appe ndi x I, ect ion l. 3.3.3.7 states that:

"A nal ys es of les lik e ly but plau s ibl e sce nar ios are not m e ant t o be 'wo rs t-ca se' ana lyses a nd s ho uld not utili ze a se t of ' wor t-case ' param ete rs. "

A techn ica l s upp o rt d oc um e nt (TS D) th at describes th e resu lts of th e s ur vey, th e d ose ca lculat io n s, and the ri sk calcu lat ions, wi ll be s ubmitt ed to the NRC staff. This approac h, i.e.,

s ubmi tt in g d ose modelin g resu lts e ith er in the L TP o r in anot her d oc ument, in thi s case a TSD, is consistent wit h the g uid ance in NUREG -17 57. 17 The DRP Survey Plan In the abse nc e of NRC g uidan ce for how to devise a s urvey plan w ith the objective of identi fyi ng DRPs over a large area s uch as a nucl ear power plant decommis s io nin g s ite, Z ionSo lution s d ev ise d a nd impl e mented a s urvey that was foc u se d o n cove rin g a large area to id ent ify DRP s.

The survey approac h re li ed on proven techn o logy and in corporated avai la bl e indu s try ex p erience in c o nductin g field surv eys. It a lso took in to co ns id erat io n the in format io n pro vided by s taff in the Octo ber 14, 2021, RAI letter. ZionSolutions be li eve s t hat thi s approac h pro v id es a high level of confide nc e that remaining DRPs wi ll b e detected a nd remediated. T h e DQO s of thi s sur vey plan and the equ ipm ent u sed s uppl e m e nt the FSS and provide confidence th at any remaining DRPs that mi g ht p ose an un acceptab ly hi g h ri s k to a member of the public have been identifi ed and remediated.

Relevant License Termination Cases ZionSolutions a lso cons id e red the ap p roach taken by ot her lic e n sees. There ar e at least three notab le and re levan t examp les w her e DRP s a l o were a co n ce rn.

Durin g ORIS E confirmatory s urveys fo ll ow in g FSS at Rancho Seco, areas of e levate d activi ty were identified th at we r e due to DRPs. Si n ce ORIS E on ly s urve yed p o rtion s of applicable survey unit s that p ote nti a ll y c o uld h ave DRP s, NRC re quested Rancho Seco perform add iti o nal s urveys.

Rancho Seco developed a particle sca n p rotoco l ba sed o n the abilit y to d etect a 1 µCi Co -60 particle. The lic en ee co ndu cted ad diti ona l s ur veys a nd provided a de sc ription of its action s in

17 NUREG -1757, Vol. 2, Rev. 2, Draft, Sec ti o n 5. 1, Introdu ction, p. 5-1, November 2020.

Page 45 of 96 ZionSolutions, LLC ZS-2022 -0 l 0 Attachment response to the DRPs and a dose analysis in its site release request. 18 Rancho Seco identified 32 elevated activity items in its re-surveys and remediated any identifi ed areas of elevated radioactivity. The NRC staff reviewed the licensee ' s actions and determined that they were acceptab le. In August 20 18, the NRC terminated the license. As sh o wn in the response to Specific Con s id e ration I b, the to wed arra y us ed for the Zion DRP s ur v e y a po teriori MDA value for Co-60 is 0.12 µCi. This is significantly more conservative than the Ranch Seco detection capabi I ity.

The license termination of the Shel well Services site in Hebron, Ohio provides another example of acceptable methodologies for license termination where DRPs are concerned. The NRC staff u s ed a probabilistic approach to ca lcul ate an " expectation dose" for partic les potentially remaining on the site after license termination. T he surveys used for s ite release utilized µR do e rate meters. The approach approved by the Comm ission for the termination of the She lwe ll license is summarized in SECY-98-117. The NRC terminated the license in July 1999. Our response to Specific Consideration 3b provides the expectation dose calculation for the Zion site u s ing this methodology.

1n 2005, Yankee Rowe performed an evaluat ion to evaluate the effectiveness of in-situ gamma pectroscopy to detect DRPs (Y A-REPT-00-018-05). A concentration of 1.0 pCi /g (Co-60) was fo und to correlate to a discrete point so ur ce of ap pro ximate ly 3.2 µCi. This activity va lue was considere d as the discrete particle of concern. Discrete particles exceed in g this magnitude were considered to be readily detected during character ization or investigation surveys. The MDCs associated with handheld field instruments u ed for scan surveys were considered capab le of detecting very sma ll areas of e levated radioactivity that cou ld b e present in the form of di screte point sources. Yankee Rowe determined that the minimum detectable particle activity for these scanning instruments and methods corresponded to a small fraction of the TEDE limit provided in 10 CFR 20 Subpart E.

The approac h taken in the DRP Survey Plan is mor e conservative than the o n es impl e mented at Rancho Seco, She lwe ll, or Yankee Rowe. Th is section provides an overview of the approach. A complete description is contained in the DRP Survey Plan ; respon e to NRC ' s specific considerations po ed in the RAI letter are given below.

The Towed Array ZionSolutions devised a surve y approach that used a towed 62 inch-wide array of six Ludlum Model 44-10 2 " x 2" Nal(TI) detectors mounted on a utility terrain vehic le (UTV) and attached

18 Letter, Einar Ronningen to.S. NRC, " Phased Release of the Rancho Seco Sit e," Sacramento Muni c ipal Utility District, ADAMS Accession o. ML 091670511, June 8, 2009.

Page 46 of96 ZionSolutions, LLC ZS-2022-0 l 0 Attachment to a Lud lum M ode l 4612, a 12 -c h a nn e l co unter data logge r (th e "towe d a rray"). 19 T h e unit was eq ui ppe d w ith a s in g le T rimble GA8 10 GPS rece iver and a nt e nn a co mbin e d with a hi g h accuracy in e rti a l m eas ur e m e nt unit (IMU). T h e L udlum Mode l 4612, Trimb le GPS receiver, and th e IMU are inte gra t e d u s in g an o n-b oard tablet or laptop co mput e r (co ntrol compute r ) runnin g the sca nnin g softwa re.

The towed array ha s s ig nifi cant a d va ntages ove r hand sca nnin g. It provides th e abi lity t o cover a large area fa r m ore effic ie ntl y than hand sca nnin g. T hi s is co n s is te n t w ith the proposed g ui dance in the updat e to MARSS IM (Draft R ev. 2) where the NRC s taff was inv o lve d. Whil e we recog ni ze thi s draft is not to be c it ed o r qu o ted, we beli eve it is in for mati ve becau se it recogni zes that major advances in technol ogy ha ve occ urr e d s in ce th e las t revision. The se a d va n ces h ave encouraged th e use of a ut omated sca nnin g as a v iabl e o pti o n for large area s urveys. In a dditi o n,

MARSS IM (Draft Re v. 2) a lso recog ni zes that h a nd-held s urvey in g remain s the more econo mical choice for a s m a ll area, but as the area incr eases, th e cost of an automated system bec omes an in creasing l y worthwh il e in vest ment to redu ce manual labor costs associated with s u rveyi ng as th e case for th e Zio n DRP s urvey.

Key Features of the Towed Arr ay Some ke y feat ur es of the s urvey meth o d o logy are:

Scan parameters. The towed arra y wi ll be operated o n a c o ntinuous basis at a speed n ot to exceed 0.6 m /sec (1. 3 4 mph ). The detectors wi ll be app roximate l y 4 " from the so il s ur face.

Detection efficiency. T h e a priori MDAs for the towed arra y are described in Section 3.4. 1, Gamma Scan Survey with Towed Array, of th e DRP Surve y Plan.

Hard to detect radionuclides. Hard-to-detect (HTD) radionuclide co n ce ntrati o n s w ill be determined by dir ect a n a lys is. A ny id entified no n-Co - 60 DRP s w ill b e sent to the off-s ite lab oratory for a nal ysis of th e full s uit e of radionuclides.

Area to be s urveyed. 100 % of th e access ibl e surface area of the s urvey uni ts li sted in the DRP S urvey Plan were sca nn e d u s in g the towed array. Areas inaccess ibl e20 to the t owed array were surveyed us ing hand-scann in g m et hods.

19 The towed array and o th e r aspects of th e app roach ar e d esc rib ed in detai l in Sectio n 3.4, Des cription of Plann ed DRP Survey Activities, of th e DRP S urvey Plan.

20 The term in accessib le in thi s context m eans th at the towe d arra y s urv ey co uld not be p erfo rm e d w ithin the paramete rs t hat were det ermined in the probabili stic mode llin g in TSD 2 1-001, Revision 2.

Pag e 47 of 96 ZionSolutions, LLC ZS - 2022 -010 Attachme nt Basis for Se lecting Areas to Survey Thirty -s ix s u rvey unit s were se lected for s urve y in g usin g t he DRP Survey Plan. The detailed justificat ion fo r se lectin g th ese a reas is pro v ided be low in the response to Specific Co ns id eration 4a. These areas we re e lected beca use they were co n sidered at hi g her r isk fo r t h e presence of DRPs based o n decommissioning proj ect expe ri e nce (e.g., a loca ti o n w h e re c lean co ncrete d e m o liti o n debri s (CCDD) was te mp ora ril y sto red o r transported th roug h), or where prev io us s urveys id entifi e d particles or areas of e levate d ac ti v ity.

The areas w ithin th e sco pe of the DRP S u rvey Plan wou ld be expa nded, as necessary, as a result of invest igations performed to bound areas of e levated radioact iv ity o r as a re s ult of remediati o n.

T he rationa le for areas not in c luded in t he DRP S ur vey Pla n is that based o n pro cess knowled ge and the re s ul ts of previous radio log ica l s ur veys, in c ludin g but not limit e d to s uc cessf ul per for mance of FSS a nd ORIS E ind epe nd ent ve rification surv ey s, there is a low potential for the prese nce of DRP s.

Detailed Inv es tigation of Elevated Activi ty Detected by th e Towed Array The investigation was d es igned to id ent ify and remove DRPs th at p ote ntiall y were the so urc e of the e leva ted reading by the t owe d arra y. Any time th e in vest igat ion leve l was exceeded durin g the towed arra y s urvey, a d etai led in vest igat io n was performed. A s ummar y of h ow the det ailed in vest ig ation was co nduct e d21 is as fo ll ows:

Scan th e elevated area us ing a hand -he ld Nal d etecto r to locate the precise area of th e e levated ac ti v ity. Mark th e lo cation in the field with a fl ag o r s imilar. If the area of elevated act ivity cannot be dupli cated, th en make a notat io n in the field notes a nd no further actio n s are necessa ry.

If a n area of elevated act iv ity is detected, obtain a measurement using a portable gamma spectro sco py in strum ent a nd a 10-minute co un t.

If a plant-related radionuclide is id ent ifi e d, co ll ect a so il samp le in the locatio n d own to a depth of 12 in c h es, captu rin g at least 2 lit ers of so il to rem ediate the potential DRP.

Spread the so il sampl e o ut into a pan o r ot her appropriate container to an approx im ate 1-inc h thickne ss. Use th e hand-held Nal detector to try to iso late a potential DRP. Any DRPs id ent ified w ill be cap tur e d and tho se containing n on-Co -60 plant-related rad ionuc lid es will be se nt to a n off-site laboratory for full suite radio nu clide a nal ys is.

2 1 T h e detai le d inv estigat io n pro cess, in c ludin g th e isolatio n and co ll ect ion of DRPs and surr ou ndin g so il, is described in Section 3.4.3, Scan in vestigations, of the DRP S urvey Plan.

Pa ge 48 of 96 ZionSolutions, LLC ZS - 2022 -010 Attachment

If a DRP was captured in an in vestigat iv e so il samp le, rescan t he samp le voi d u s in g the hand-h e ld Nal det ector to ver ify that the locat ion has be e n successfu ll y remediated.

If additional e levated rea ding s are e n co unt ered, co ll ect additional sa mpl es fo r sc re enin g, as de scr ibed above.

Hand Scanning Areas inacce ss ible to the tow ed array were s urve ye d u s ing hand-scan ning meth ods. T h e protoco ls for gamma scanning with h and -h eld detectors are delineated in the DRP Survey Plan and summar ized below:

Technicians w ill sca n s low ly (0.25 m /sec or s lower) in a serpent in e fas hi o n w hil e maintaining the det ector e nd cap n o m o re th a n 2 " from th e soil s urfac e.

Techn icians wi ll pause during the survey w h en the audibl e outp ut s ig n a l from the detector indicate s e levated act ivity, suc h as from the presence of s u spect DRPs.

T h e investigation leve l for hand-h eld sca nnin g is minimum detectable count rate (MDCR) p lu s background. This inve st iga ti on level is a secondary co n siderat io n to the monitoring for var iation of det ector a udi o o utpu t.

In the eve nt th at e le vate d activity was d etecte d by h a nd sca nnin g, a detailed inv estigat ion, as described in the previous section, would be co ndu cted.

Systematic Soil Sampling ZionSolutions designed a syste m at ic so il samp ling pl an as recomm ended by NRC staff in RAi l 0, Spec ific Co n si d e rat io n 2a, to augment the s urveys described above. T h e samp lin g plan (describe d in detail in the DRP S ur vey Plan) is inte nd ed to pro v id e add iti ona l confide nc e tha t potential DRPs h ave be e n id ent ifi e d and remediated by selec tin g areas for a nal ysis that hav e not been identified by sca nnin g as co ntainin g e levate d activity. This samp lin g pl a n uses a

" presence /absence " s urv ey d esig n to se lect add ition a l s ur vey areas for detailed in ves tigati o n.

This investigation s uppl eme nts the investigatory samp lin g co ndu cted in areas of e levate d activity.

T h e area of int erest (t he 36 survey unit s) was divided into 10 3,529 grid ce ll s l m 2 in size. Grid ee l I sizes for presence /a b sence s urvey design correspond to the footprint of the samp lin g methodology ; in th is case, the samp lin g footprint is a 1 m 2 area where 5 total soi l samp les were col lected. For each gr id cell, l samp le was co ll ected at the center of the gr id ce ll and 4 sa mpl es were co llect e d at eac h of th e car dinal dir ections (N, S, E, W) 0.5 m eq uidi sta nt from the center sample.

ZionSolutions samp led 155 gr id ce ll s using th is approach. V is ua l Sample Plan (VSP), a software tool for s urvey design and data assess m ent u se d to design t h e presence /absence samp lin g plan,

Page 49 of96 ZionSolutions, LLC ZS - 2022 - 0 l 0 Attachment determined that if 155 of the 103,529 grid ce ll s are samp le d and 3 or fewer of the 155 samp led grid ce ll s co ntain DRPs, then th ere will be at least a 95.4% confidence that at least 95% of the grid ce ll s d o not co nt a in DRPs. A dditi ona ll y, if no more th a n 0.5% of the gr id ce ll s in th e population are assumed to contain DRP s, then there wi ll be n o more t han a 0.8% probability of conclud in g that the pop ul ation co nta in s DRPs.

Estimate of DRP Risk The exposures from the inhalation, ingestion, a nd skin expos ure ( in cludi n g t he effect ive d ose equiva lent) of the hypothetical DRP source term are treated as LLBP sce n a ri os due to their low probability of occ urr e nc e. Treating th e low-prob abilit y DRP exposure as an LLBP sce nari o is cons iste nt w ith the approach approved in the Z io n L TP for assess in g the low -p robabi lity scenario of the we ll driller contact in g the A ux ili ary Building drains, w hi ch was a lso designated as an LLBP scenario.

In accorda n ce with NUREG -17 57, the evaluat ion of LLBP exposure scenar ios ensures that

" unacceptably high ri ks would not result," but are not cons id ered compl iance scenar ios.

Accordingly, the dose from the hy poth etica l DRPs will not be added to the Z ion comp lianc e dose. Rather, the hypothetical DRP d ose will be u sed to better risk inform the decision t o terminate the li cense.

An unacceptably high risk is viewe d as that cor res p o ndin g to th e public dose limit of 100 mrem/year TEDE w hi c h represents a li fetime fata l cancer risk 22 of 4x10*3. Issued in s upp ort of the promulgation of the licen se termination rul e (LTR), SECY-97-046A sta te s that the fatal cancer risk corresponding to the 25 mrem/year unr estricted u se criterion is an order of ma g nitud e lower at 4x10*4 and that t hi s risk is estimated ass umin g a risk coefficient of 5x10-4 per rem and a 30-year li fet im e expos ur e.

To justify the designation of the h y p oth etica l DRP expos ur e path way as an LLBP sce nario, the probabilities of DRP in gest io n and inhal at io n were compared to the probability of drilling int o the Auxi lia ry Building drains, w hich was accepted by NRC as an LLBP sce n ario in the Zion LTP. The probability of a drill co ntactin g the Aux iliar y Building drains was calcu lat ed to be l.Sx 10*3 for a sing le we ll drill ed o n th e ite.

The probability of a future site resident ingesting or inhaling a single DRP i much lower than drilling int o an A ux ili ary Building dr a in ; ZionSolutions has calculated these probabilities to be l.6xl0* 8 and l.7xlo* 10, respectively,23 assuming a s in g le DRP is present. The site resident is assumed to occupy the s it e for a 30 -year period in accordance with SECY - 97 -04 6A.

22 SECY-97-046A, " Final Rule on Radiolog ical Criteria for Licen e Termination," March 3 1, 1997.

23 See the response to RAJ-I 0, Specific Consideration 3b, be low, for the calculation of these probabilities.

Page 50 of 96 ZionSolut ions, LLC ZS -2022-0 l 0 Attachment The expectation dose is ca lculate d by mult ip ly in g the probability of inhaling or ingesting a particle in a given year by the dose from the particle 12. Inhalation and ingestion effect ive d ose equivale nt s have been calcu lated for particles w ith Co-60 or Cs -1 3 7 that correspond to the 50 th percentile a posteriori MD As. T h e final li fe tim e probability of a sing le DRP being d eposited in the s ki n is I.2x I 0-7 _ The DRP direct sk in exposu re effective dose equiva le nt s were ca lc ul ated using the EPRJ 1002823 guidance. This g uid a nc e a ll ows for dir ect compariso n to the lic en se tem1ination c rit eria of 25 mrem TEDE /yr assum in g that the exposure will o ccur (i.e., ignoring the low probability of a n exposure event).

The dose to th e average member of th e critica l gro up from DRP expos ur e is a low probability,

once in a li fetime eve nt, as compared to t he ass um e d 30-year li fetime exposure from di spe rse source terms s uch as soi l. Therefo re, the dose (TEDE) from t h e hypothetical DRP wi ll be multiplied by the risk coefficient app li ed in SECY-97-046A, i.e., 5x10- 4 per rem, an d co mp ared to the risk of 4xl 0- 4 that r eprese nts the 25 m re m /year unr est ri cted use criterion. If the ri sks from the LLBP DRP ingestion and inhalation expos ur e scenarios are below 4x10-4, they are n ot conside red un acceptab l y high.

NRC SPECIFIC CONSIDERATION 1:

The NRC staff offers the following information relevant to scan sensitivity of survey instruments for surveying the Zion discrete radioactive particles:

NRC SPECIFIC CONSIDERATION la:

The results of the limited-scope NRC confirmatory survey in April 2021 identified three types of discrete radioactive particles at the site : (1) cobalt-60 primarily, with other activation products, in the form of activated metal; (2) potentially activated bioshield concrete; and (3) potentially irradiated fuel fragments. One of the objectives of scoping for the revised survey should be a determination of an appropriate surrogate ratio that is based on adequate characterization information. For each particle type, consider the use of surrogates for hard-to-detect radionuclides and for the calculation of total activity. In addition, consider how differences in radi o nuclide composition of the bioshield concrete and irradiated fuel fragments would be taken into account for calculating the scan MDAs. Relevant information from the licensee 's RAI respon se s to the NRC letter dated August 19, 2021 (ADAMS Acces s ion No. ML2 l 231Al 87) should also be taken into account.

ZIONSOLUTIONS RESPONSE:

A survey plan, the " Survey Plan fo r Discrete Radioactive Particle Identification and Remediation," ZS -LT - 07, Revision 1 (the "DRP Survey Plan"), was designed specifica ll y for detecting and removing di screte radioactive particles. The DRP Survey Plan is included as part of the ZionSolutions respo n se to RAI-10.

Page 51 of96 ZionSolutions, LLC ZS - 2022 -010 Attachment In preparation for performing the DRP sca n, eac h of the s ix 2"X2 " NaJ detector s to be u sed for the towed array was calibrated using two NIST-traceable point sources, Cs-13 7, whic h is an HTD surrogate, and Co-60. The ca librati on involved the detem1ination of detection efficiency versus distance, x, between th e so urce s and the detector ranging from co ntact to approx im ately 20 inches. As part of the y tern capability eva luati on, a mathem a ti ca l Monte Car lo m o d e l wa deve lo ped to det er mine a di st ribution of d etec ti o n efficien~ies and MDAs for DRP s while vary in g the 3 -dim e n s ional hypo theti ca l p a rticl e locations relative to the detector s. The mod e l u ses a curve-fit of the calibration efficiency (E) data (fro m 4 of the lowes t efficiency detector s for the a posteriori eva lu ation) of the following math e matical form to d e termine the mean detection efficiency during each co ll ection interval (l sec):

Equati on 8 - Calibration Efficiency

The DRP Surv ey Plan addre sses the need to account for HTD nuclide s in Section 3. 5, Data Evaluation:

Transuranic hard-to-detect (HTD) radionuc lid es will be determined by ratio to Am-241, a nd other HTD radionuclid es wi ll be determined by ratio to Cs-137, based on the ratio s identified in particle S0126 identified by ORJSE during the Apri l 2021 s urve y.

We believe that the efficiency and MDA di s tribution s for Cs -1 37 are reasonably representative of other gamma - emitting radi o nuclide s that ma y be pre se nt in DRP s g iven the m o derate gamma energy range of Cs-137 compared to these other radionuclides.

Those portion s of the respon ses to the NRC's August 19, 2021, Reque s t for Additiona l In fo rmation that are relevant ha ve been inc o rporated into the DRP Survey Plan and are called out here as nece ssa ry.

NRC SPECIFIC CONSIDERATION lb:

For estimating the revised scan sensitivity of the survey instruments, expressed as a scan MDA,

the scan MDA equation should be adjusted for a decreased observation interval for a particle in comparison to a diffuse source of residual radioactivity.

ZIONSOLUTIONS RESPONSE:

The detection efficiency and MDA model developed for the towed-array account for the scan observatio n interval (1 sec) used for the scan survey conducte d at a nominal transit ve locit y not to exceed 0.6 m /sec (1.34 mph). The a priori MDA s for the towed array are described in Section 3.4.1, Gamma Scan Survey with Towed Array, of the DRP Survey Plan. The detail s of system calibration and the se n s itivity are de sc ribed in TSD 21-001, Re v is io n 2, "Ca librati o n and Di sc rete Radioa ct ive Particle Detection Sensitivity and Performanc e Assess ment for a Ludlum Pa ge 52 of 96 ZionSolutions, LLC ZS-2022-010 Attac hment 44-10 Six-Detector Array." T he calculated 50 th percentil e a priori MDA values from TSD 21 -

001, the po s t-proce ss (a posteriori) data assess ment se n s itivity ba sed on a seve n s igma criterion, and t he array drive-over test s are s hown in the following table.

The Ai-ray Drive-Over Te s t. A n a ddi tiona l emp iri ca l test was performed to d emo n stra te th e abi lity of th e towed a rr ay to detect actual e leva t e d activity ite m s th at were collected durin g prior survey activ iti es at Zion. The Co -60 act ivity of the DRP s we re determined by laboratory ga mm a spectroscopy ana lys is. The items we re se lec ted based on the c lo eness of their activ iti es to the calculated a priori MDAs. One piece of elevate d activity concrete rubble (L l-12 203 B-FJGS-2 1 l-CV) and 2 DRP s (LI-12112A-FJGS-21 l-DP and LI-12113 A -FJGS-2 1 l-DP) were se lect ed for this eva luati o n. These item s we re analyzed by ga mma spe ctro scopy at G EL Laboratories.

The tests were conducted o n-site in actual field conditions. The it e m s we re placed o ne at a time onto the ground a nd the array was dri ve n over th e tar get it e m. The three item s use d in the te st were succe ss fully located by the system operator during th e live time monitoring. The file s were then post-processed u s in g off-th e-shelf ES RI ARCMap 10.8 GTS software for dat a analysis a nd reporting.

An assessment was also done of the DRP d etection se ns itivity for th e identificati o n of potenti a l locatio ns for follow-up inve st ig ations us in g Arc-GIS po st-proce ss ing. The re sult s of the data int erpre tati o n u s in g A r c -GIS for two of the three it e m s showed th at the syste m can id entif y the pre se nce of the se particle s during a scan array survey with these DRPs at the gro und s urface.

Item s Ll-12203B-FJGS-21 l-CVand LI-12112A-FJGS-211-DP were detected in the post proc ess ing anal ys is.

The third item (Sa mple LI-12113A-FJGS-21 l-DP) was not identified during po st-processing.

This particle was determined to have 0.08 µCi of Co-60 by laborat ory gamma spectroscopy, which is 20% below the activity of parti c le LI-12112A-F JGS-21 l-DP. The likel y cause of the missed detection was the position of the particle relative to the start of the I-second acquisition,

t. For example, if t2 ( the probabilistic tim e from detector array centerline to end count end-time) were at or near zero, the det ect io n efficiency would be at a low value potentiall y causing a non d ete ct ion.

The detection of item LI-12112A-FJGS-211-DP with an activity of0.10 µ C i is close to the the ore tical prediction s of both the probabili st ic model and the post-surve y data assessment.

This test clearly shows that the system i s a ble to detect DRPs of 0.10 µCi of Co-60 and 0.04 µ C i of Cs-13 7. Both of these va lu es are below the a po steriori MDC. The activity and the corresponding d oses of the se detected particle s well bel ow the activity of do se s ignificant p art ic le s.

Page 53 of96 ZionSolutions, LLC ZS-2022-0 l 0 Attachment

Table 9-DRP Detection Sensit i vity ------'=--------.-----------,

Methodology Co-60 Sensitivity Cs-137 Sensitivity

(µ.Ci) (µ.Ci) a priori Probabil ist ic Model, sot1, Perc enti le 0.06 0.15 MDA Post-Process data Assessme nt, 7 sigma 0.12 0.41 Array Drive-Over Test 0.10 0.04

NRC SPECIFIC CONSIDERATION le:

The detector s peed over the land s urface during the survey (e.g., 0.25 meter per sec ond or other value) a nd the transect widt h of the survey path s hould be factored into the scan MDA calculation and the s urvey design, accordingl y. !

ZIONSOLUTJONS RESPONSE:

The range of detector speeds and the transect w idth of the s urve y path have been factored into the sca n MDA as probab ili stic parameters as de scr ibed in t h e DRP Survey Plan and in TSD 21-001. In addition, fo r the a posteriori sensit ivity eva lu ation, we incorp orate d the detection effic iency, scan spee d, and the ranges of detector height from the ground as probabilistic parameter s.

NRC SPECIFIC CONSIDERATION ld:

If collimators are used on the detectors, an estimate of the change in detector response ( e.g., axial response and reduced background), as well as how the collimated detectors are addressed in the survey plan and scan MDA equation, should be considered. Additional factors, such as a shorter observation interval as noted in item I B above, should be considered for estimating the revised scan MDA if detectors with collimators are used for the s urvey.

ZIONSOLUTJONS RESPONSE:

As described in the DRP Survey Plan, collimators were not used during scanning.

NRC SPECIFIC CONSIDERATION le:

The method for calculating the efficiency of the detector s hould be described in the survey plan.

If collimators are use d on the detectors, th e calcu lation method should account for the detector response, as noted in item ID above.

ZIONSOLUTJONS RESPONSE:

TSD 21 -001 pro v ides a summary of the methods for determining the mean detector effic iency di strib ution s for calibration and assessment of the system performance. The a priori ana lysis

Page 54 of96 ZionSol utions, LLC ZS - 2022 - 0 10 Attac hm e nt m ode l used the mean of al l detector effic ienc ies fo r eac h distance whereas the a posterior i model used the fo ur lowest d etector effic ie nci es as a conservative est im ate of syste m sens iti v ity.

Col lim ators were not used on the d e t ectors.

NRC SPECIFIC CONSIDERATION lf:

A range of scan sensitivities for discrete radioactive particles located between the land surface and six inches or deeper below the land surface s hould be considered in the su rvey design. The assumed depth of particles informing the s urvey design should take into account the likely actual depth of the particles given the site history and prior survey results. For example, a *' worst-case "

scan MDA may be calculated for discrete radioactive particles located at 6 inches or deeper below the land surface, and/or the depth below which a discrete radioactive particle of nominal activity cannot be detected. Then, an upper bound on the range of scan sensitivity and discrete radioactive particle detection may be calculated as a '"best-case" scan MDA, where the discrete radioactive particle is located on the land surface.

ZIONSOLUTIONS RESPONSE:

To estimate the effect of increased DRP depth in so il, Micros hi e ld v8.03 was used to calculate relative reduction/attenuation factors by modeling a point so urc e for var ious distances and ratioing the results to the DRP location on the ground surface at a distance to the detector's centerli ne of 4 inches for only Cs - 137. Co - 60 was not used in the assessme nt, because the factors wou ld be less conservat ive due to Co-60 ' s higher gamma e n ergy. The analysis modeled so il as concrete with a density of 1.6 gl ee and the dose rates used to d etermine the reduction factor associated w ith gamma ray build-up. The resu lts of the ana lysis are summarized in the table below.

Table I 0- Cs-13 7 Response R edu ction at Depth Distance Cs-137 Below the Response Surface (in) Reduction Factor 1 2.6 2 4.0 4 8.0 6 16.2 8 32.2 10 59.3 12 101.0 This ana lysis shows that for a DRP at 6 inches below the s ur face, the detector ' s effic iency wi ll decrease by a factor of 16, resu lt in g in an increase in the DRP MDA by the same factor for Cs-13 7. T h ese reduction factors can be applied to the MDA distribution for Cs-13 7 to assess the

Page 55 of 96 ZionSol utio ns, LL C ZS - 2 022 - 0 l 0 Attac hm e nt overa ll imp act of DRP s MD As be low th e so il s ur face. T hi s ran ge in c lud es MD A s fro m " w o r st ca se " to " bes t-c ase."

NRC SPECIFIC CONSIDERATION lg:

Th e s urv ey prot o c o l should consider how the s urve y or will pause durin g th e s urvey, using th e output signal from the detector to identif y suspect discrete radioactive particles. Also, the surve y p ro t oco l s hould c o n s ider the in v es tigati o n level a s a sec o nd stage, in unit s of count s per minute above the background count rate.

ZIONSOLUTIONS RESPONSE:

T h e towe d array is d es ig ne d to o pe rat e in a co ntinu o u s m a nn er, a nd as s uc h th e s urvey prot oco l d oe s n o t a cco un t fo r a n o p era t o r to p a u se base d o n o u tpu t s ign a l.

100 % o f th e ac cess ible s urfac e area o f th e s urvey unit s li s t e d in th e DRP urvey Pl a n were sca nn e d us in g th e t owe d a rr ay. A reas in access ibl e to th e towe d arr a y we r e s urveye d u s in g h a nd sca nnin g m e th o d s.

T h e fo ll ow in g p ro toco ls fo r ga mma scannin g w ith h a nd-h e ld det ec tors ar e d e lin ea t e d in th e DRP Sur vey Plan :

T echnician s w ill scan s low ly ( 0.25 m /s e c o r s lowe r) in a se rp e ntin e fas hi o n w hile m a inta inin g th e d e t ec to r e nd ca p n o m o re th a n 2 " fro m th e so il s ur face.

Co llim ato rs w ill no t be utili ze d.

T ec hni c ia n s w ill pau se durin g th e s urvey w h e n t he a udibl e o utput s ig na l fro m the det e cto r indic a t es e le va t e d activi ty, s uch as fr o m th e pre sence o f s u sp e ct DRP s.

T h e in ves ti g a t io n le ve l fo r hand-h e ld sca nnin g is minimum d e te cta bl e c o unt rate (MD C R) plu s back gro und, but thi s inv es ti g ati o n leve l is a se c ond ar y c o n s id e ration to th e m o nit o rin g fo r v ariati o n o f det e cto r a udi o o utpu t.

NRC SPECIFIC CONSIDERATION lb:

In addition to surveyors monitoring survey instrument physical meter movements and pre-set alarms, the existing NRC guidance on survey techniques recommends the use of additional methods to improve the human performance factors, such as headphones, to aid the surveyor ' s efficiency and ability to identify areas of concern when performing surveys. The revised survey plan should consider the use of headphones or other means for improving the surveyor performance for detecting discrete particles or other areas of concern.

Pa ge 56 of 96 ZionSolution s, LLC Z S-2022-010 Attachment ZIONSOLUTIONS RE SPONSE:

In strument headphones were not uti li zed und e r the DRP Surve y Plan, becau s e the detectors used in the s urve y, Mode l 2350-ls, do not have headphone jacks. ZionSolution s instructed tec hnician s, as p a rt o f th e trainin g for th e DRP Surv ey Pl a n, to cl ose ly mon itor th e audib le o utput fr o m th e in s trum e nt. Zi o nSo lut io ns be li eves th a t b eca use D&D o p e rati o n s ar e no lo nge r in pro g ress and the background no ise at th e s ite is no min a l ( no rmal e nv ironmental a mbient lev el s),

tec hni c ian s w ill be ea s il y abl e to det e ct c han ges in a udibl e o utput.

NRC SPECIFIC CONSIDERATION li:

Personnel training s hould be considered to ens ure that surveyo rs can achieve the performance bases of the survey protocol (e.g., th e ass igned surveyor efficiency, maintaining detector distance to the land surface at the assigned scan speed, etc.).

ZIONSOLUTIONS RESPONSE:

ZionSolution s conducted personnel training for each s urve y or who participated in the implementation of the DRP Survey Plan. Ind ivid u a ls performing field survey and samp lin g acti v it ies and reviewing co ll ected data from field measurements or laboratory data reports were trained in the use of instrument s, device s, and procedure s, as app li cable to the tasks they wi ll be performing.

Operators of the towe d arra y are trained to operate the vehicle at a constant speed, not to exceed 0.6 m/sec (1. 3 4 mph). The detector to ground distance remains nominall y con s tant, and variabi li ty is accounted for as a probabilistic parameter. For hand scanni n g, prior to being qualified, a technician wa s observed by a subject matter expert during training to verify that they are maintaining the co rrect scan speed and detector di s tance spec ific to h and scanning in the DRP Survey Plan (maxi mu m 0.25 m /sec and maximum 2 " from s urface).

NRC SPECIFIC CONSIDERATION 2:

The NRC staff offers the following con s iderations for developing a revised sample collection and laborato ry analysis procedure relevant to the Zion di sc rete radioactive particles to be collected during the surveys:

NRC SPECIFIC CONSIDERATION 2a:

A systematic soil sa mpling plan should take into account a chosen confidence le ve l for the purpose of performing statistical tests to determine what proportion s of the investigation areas are impacted /not impacted by the presence of discrete radioactive particles and below the scan se n s iti v ity of the s urvey.

Pa g e 57 of96 ZionSolutions, LLC ZS - 2022 -010 Attachment ZIONSOLUTIONS RESPONSE:

A syste matic soi l sa mpling plan was de ve lope d in the DRP S urvey Plan that utili ze d a

" presence /absence" s urvey d es ign. The area of int erest (36 s urvey unit s denoted in Ta ble 3 of the DRP S urvey Plan) wa divided into 10 3,529 grid ce ll s 1 m 2 in s ize. Gr id ce ll izes for presence /abse n ce s ur vey d esig n cor respond to th e footpr int of th e samp lin g m ethodo logy; in thi case, the sa mplin g foo tprint is the I m 2 area w he re 5 total so il sa mpl es w ill be collected. For eac h grid ce ll, 1 samp le was co ll ected at th e center of th e grid ce ll and 4 samp le were co ll ected at eac h of the cardinal dir ect io n s (N, S, E, W) 0.5 m e quidi sta nt from th e center sampl e.

Visual Sample Plan (VSP), a softwa re tool for s urvey de s ign and d ata assessment that was u se d to design th e DRP Survey Pl an, d e t ermin ed that if 155 of the 10 3,529 g rid ce ll s are sa mpl ed a nd 3 or fewe r of th e 15 5 ampled g rid ce ll s co nt a in DRP s, th e n ther e will b e a t least a 95.4%

confidence that at leas t 95% of the g rid ce ll s do not co nta in DRP s. Additionally, if n o more than 0.5% of the g rid ce ll s in the p opulation co ntain DRP s, then there will be no more than a 0.8 %

prob a bility of concluding that the popul at io n contains DRP s ( i.e., o b serv in g m o re than 3 grid cells assumed to contain DRP s in the sample s ize of 155 ).

NRC SPECIFIC CONSIDERATION 2b:

The revised sample collection procedures should consider how discrete radioactive particles will be isolated and collected during the survey. In addition, this procedure should consider the process used for collecting soil around any discrete radioactive particles identified, and separate laboratory analyses of those soils.

ZIO SOLUTIONS RESPO SE:

Elevated Activity Investigations. Detailed investi ga ti o n s were performed an y time the inve st ig ation leve l was exceeded durin g the sca n survey. The detailed inve s tigation proces s,

including the iso lation and collection of DRP s and s urrounding soil, is de sc ribed in Sect ion 3.4.3, Scan Inv es tigations, of the DRP Survey Plan and s ummarized belo w :

Scan the elevated area u s ing a hand-h e ld Nal detector to locate the preci se area of th e elevated activity. Mark the locati o n in the field with a fla g o r s imilar. If th e area of e le vate d act iv ity cannot be dupli cate d, then mak e a n o tati o n in th e field n otes and no further actions are necessary.

If an area of e leva ted ac tivity is d etecte d, obtain a measurem e nt u s ing a portable gamma spectroscopy in strument a nd a 10-minute count.

If a plant-r e lated radionuclide is id e ntified, collect a soil sample in the location down to a depth of 12 inche s, capturing at least 2 liter s of so il. This w ill remediate the potential DRP.

Pag e 58 of96 ZionSolutions, LLC ZS-2022 -0 l 0 Attachment

If the sampl e has bee n detected in an area of e levated back gro und, n otify the rad iol ogical e n g in eer t o co n s id er moving the samp le to an area of lo wer backgro und for further ana lys is.

Spread the o il s amp le out into a pan or ot her appropr iat e c o nta in er to a n approx im ate 1-inch thickne s. Use the h a nd-h e ld a l d etec to r to try t o iso late a potential DRP.

o I f n o DRP is id e ntified d e note as s uch in the field n otes. No further act io n is required.

o I f a DRP co nta inin g o nl y Co - 60 is id entified, capture the DRP a nd arc hi ve th e sa mpl e. No further act ion is requir e d.

o I f a DRP contain in g an y no n-Co -60 plant-r e lated radionuc lid es is id e n t ified, th e n capture the DRP and send the sa mpl e t o GEL Laboratories fo r full s uit e radio nuclid e analys is.

If a DRP wa captured in an in e stigative o il a mpl e, rescan the s a mpl e void u s in g the h an d-h e ld Nal detector to ver ify that the location ha s bee n s ucce ssfull y remediated.

o If ad diti o nal e le vate d readin gs are encountered, co ll ect add iti o nal sa mples for scree nin g, as described above.

Systematic Soil Sa mpling Plan. T h e fo ll ow in g proce ss w ill be u se d to sc ree n syste matic sampl es:

If the sa mpl e h as been detected in an area of elevated back gro und, noti fy the radiolo g ica l engineer to co n s ider m ov ing th e sa mple t o an area of lower backgro und for furt her an a lys is.

Spread eac h of the five so i l samp les o ut to an approximat e I-inch thickne ss. In o rd er t o ens u re th e locat io n fr o m w hi c h th e sample was tak e n, carefull y seg regate eac h of the five pile s from one anot h er. Use a ha nd -h e ld Nal d etector (w ith th e protoc o ls o utlined in Section 3.4.2 of the Survey Plan ) to tr y to iso late a potential DRP.

If n o e leva t e d area /p ote ntial DRP is id e nti fied, den ote a s s u c h in the fie ld n otes. Plac e the so il back in the ho le and no furth er act io n is requir e d.

If an e levated area /potential DRP is identified, obtai n a m easureme nt u s in g a portabl e ga mma spectrosco p y in st rument and a I 0 - minute co unt.

o If plant-related rad ionuclid es are not id e ntifi e d, den ote the n at urall y occ urrin g radioact ive mat e rial radionuclid es in the fie ld notes. Place th e soi l back in th e h o le a nd n o further act io n is required.

Page 59 of 96 ZionSolutions, LLC ZS - 2022-010 Attachment o If the portable ga mm a spectroscopy in strume nt id entifies plant-related radio nu c lid es, then collect the s o il in an appropr iate co nta in er, reme di atin g the potential DRP.

If o nl y C o -60 i s id e ntifi ed by the po rtab le ga mma spectro s c o p y in s trum e nt, den o t e a s s uch in th e field note s and archive the samp le.

If any non-Co-60 plant-related radio nu c lid es are identified by the p ortab le gamma spectroscop y instrument, the sample w i ll be sent to G E L Laborator ies fo r ful l s ui te radionuclide anal y sis.

If a DRP wa s captured i n a soi l sample, rescan the samp le void using t h e hand-held Nal detector to verify that the location ha s been successfu ll y remediated.

o If add itiona l elevated reading s are encountered, co ll ect add it ional soi l m aterial for scree nin g, as described above.

Justification for u se of th e Portable Gamma Spectroscopy In s trument. The use of a portable gamma spectroscopy in strument to investigate e levated gam m a scan readings is an industry standard that h as been u se d in numerous past decommissioning projects. Qualitative measurement s obtai ned by the instrument can provide real -tim e ind ications in the fie ld of w hether an e levated reading is d ue to plant-related radioact ivit y or NORM. A lth oug h there m ay be concerns that some NORM (e.g., K -4 0) ma y mask plant-related gamma e mi tters su c h as Cs-137, this wo uld not be an iss u e w he n impl ement in g the DRP s ur vey. During a standar d FSS of a land s urve y unit, w here the relea s e criteria are typ ically e s tablished at near b ackgrou nd leve ls, it may be possible for K -40 to mask low leve ls of Cs-137. However, during the DRP survey, the portable ga mm a spectroscopy instrument wou ld h ave suffic ien t sensitivity to detect DRPs that co uld pose un accepta bl y hi gh r isks to a future occupant of the site.

The effectivenes s of t h e portable ga mm a spectroscopy inst rum e nt in detecti ng DRPs was va li dated u s in g actua l DRP s in an e mpiri cal investigation. This empirica l stud y is documented in TSD 21-00 1, " Ca librat ion and Discrete Radioactive Particle Detection Se n sitivity and Performance Assessme nt for a Lud lum 44-10 Six -D etector Array. " In this investigation the portable ga m ma spectrometer was shown to be capab le of identif y ing plant -re lated rad ionuclides from dose s ignificant particles wit hin a background contai nin g naturall y occ urrin g radio nuclid es.

NRC SPECIFIC CONSIDERATION 2c:

Revised sample collection procedures and planned laboratory analyses for discrete radioactive particles found during the survey should consider additional identification measures, such as labeling of sample containers with discrete radioactive particles, for the protection of laboratory personnel.

Page 60 of96 ZionSolu tions, LLC ZS - 2022-010 Attachme n t ZIONSOLUT/ONS RESPONSE:

Samp les co ntaini ng DRPs were properly labe le d as such on the c h ain of c ustody form for the protection of laboratory personnel. ZionSolutions fo rm a ll y notified GEL La boratories that every s ample the y received durin g the implementation of the DRP Surve y Plan contained a DRP. Thi s notification enabled GEL Laborator ies per sonne l to implement th e appropr iate internal procedures to en s ure protection of their per sonnel.

NRC SPECIFIC CONSIDERATION 2d:

Revised laboratory analysis procedures should consider the radionuclide composition and radioactivity levels of the discrete radioactive particles, taking into account relevant information from the licensee 's RAJ responses to the NRC letter dated August 19, 2021 (ADAMS Accession No. ML2 I 23 I A 187). The licensee should direct laborator y analyses to include the range of radionuclides potentially present based on operational and decommissioning history, and not rely solely on the radionuclide compositions identified in the limited-scope April 2021 survey.

ZIONSOLUTIONS RESPONSE:

Because the DRP Survey Plan was d es ig n ed to identify and retrieve DRPs a nd not co mpar e quantitative results to release criteria, determining the conce ntrati ons of radioactivity in each sample is not n ecessary to demonstrate comp li a nce with 10 CFR 20. However, any id entifi ed DRPs were sent to G L Laborator ie s for gamma spectroscopy analysis. No fuel-fragment particles h ave been id e ntifi ed in exec utin g the DRP Survey Plan.

The process for identifying the rad ion u clides pote nti a ll y prese nt at Zion is s umm arize d in the ZionSolutions' response to RAI -3a. Z ionSolutions re li ed upon operationa l a nd decommissioning history at Zion (inc ludin g samples co ll ected at the s it e) and indu stry reference material to develop the radionuc lid es of concern (ROC) lists that are co ntained in TSD 11-0 01, "Po t ent ial Radionuclides of Co nc ern During the Decommissioning of the Zion Stat ion," and TSD 14-01 9,

"Radionuc lid es of Co ncern for So il and Basement F ill Mode l Source Terms."

The information in the TSDs identified above is further informed by the results of the limit ed scope April 2021 inspection survey. Taken toget h er, these analyses (as documented in the cited TSDs and ORISE report) provide the basis for defining the approach in the DRP Survey Plan,

which is s ubmi tted as part of this response to RAI-10. They are a lso re li ed up on in the formulation of the approach for developing a dose estimate for DRPs as described below in ZionSolutions ' response to Specific Considerat io n 3. The data from the ORJSE report receives additiona l emp h as is in the dose fo rmul ation because it is the o nl y data th at ex ists rega rdin g certain DRPs (i.e., fuel fragments).

Page 61 of 96 ZionSolutions, LLC ZS - 2022 -010 Attac hment NRC SPECIFIC CONSIDERATION 2e:

In addition to the radioanalytical procedures described above, the licensee should consider obtaining information on the physical and chemical characterization of collected discrete radioactive particles that are relevant to internal dosimetr y calculations (e.g., the size of each particle, as well as the chemical solubility in simulated lung and digestive-tract fluids). Note that in the absence of specific information on discrete radioactive particle size and solubility characteristics, default assumptions from ICRP-30 (i.e.,fl va lue s and inhalation class) are applied for internal dose calculations.

ZIONSOLUTIONS RESPONSE:

ZionSo lution s d oes not prop ose t o s ubj ec t sample s to chemical analysis. We will use data from lit erat ur e and, when nece ssary, use th e default assumptions from I C RP-3 0 to perform internal do se calculations. Add iti onal det a il regardin g dose calculations, including th e ju stification for thi s approach, is provided below in the response to Specific Co n s ideration 3b.

ZionSolutions proposes to use alternate J i values from the literature for insoluble DRPs,

including irradiated fuel particles. While we understand that the us e of orga n dose we ightin g factors other than tho se in ICRP-30 would require an exemption, it is o ur under sta nding that us in g alternate Ji va lue s is allowable und er 10 CFR 20.

Spe cifica ll y, 10 CF R 20.1204 (c) state s:

When specific information on the ph ys ical and bi oc hemical properties of the radionuclides taken into the bod y or the behavior or the material in an individual is known, the lic ensee ma y-(1) Use that information to calculate the committed effective dose equiva lent...

Our se lect ion oft hefi va lue for Cs -137 and th e actinid es in estimating the in ges ti on do se is consistent with th e approach use d in termin ating the Shelwe ll li cense, where Dr. Keith Eckerman of Oak Rid ge Nationa l Laboratory ca lculated do se coefficie nt s for inso luble Cs-137. New do se coefficients were needed s ince the primary NRC sources for this in for mation, Federal Guidance Rep ort No. 11 24 a nd 10 CFR 20, did n o t contain coefficients for in so luble Cs-137.

This meth o d o lo gy is also s upp orte d by Regulatory Guide 8.9, Acceptab le Concepts, Models,

Equations, a nd Assumptio ns for a Bioassay Program. The u se of alternate biokinetic model s is dis c u sse d and state d to be acceptable to the NRC. Regul at ory P os iti o n 4.6 state s :

24 " Limiting Va lu es Of Radionuclid e Intake A nd A ir Co n ce ntrati on And Do se Conve rs io n Factors Fo r Inhalati on,

S ubm ers io n, And In ges tion," U.S. Env ironm e nta l P rotect io n Agency, Federal Guidance Rep ort No. 11, 520-1 020, September 198 8.

Page 62 of 96 ZionSolutions, LLC ZS-2022 -01 0 Attach m e nt Indi v idual spec ifi c retent ion and excret ion rates ma y be u sed in de ve lopin g biokinetic m o del s th at differ from the refe re nce man mod e lin g (10 CF R 20. 1204(c)). The qu a li ty a nd qu antity of d a ta used for thi s type of indi vidua l spec ific m ode lin g sh ou ld be suffic ient to justify the rev i sed model.

NRC SPECIFIC CONSIDERATION 3:

The re v ised survey plan should consider the following information for developing a dose estimate for discrete radioactive particles at the MDA :

NRC SPECIFIC CONSIDERATION 3a:

Consider the range of potential discrete radioactive particles that were not detected during the survey (be low MDA), taking into account the likely radionuclide composition, activity, physical size, depth beneath the surface, and chemical composition. See item IF above for information concerning MDA ranges and detection capability. Also see RAI-1 in the NRC letter dated Au gust 19, 2021, for additional information on origin of the particles and potential source terms (ADAMS Accession No. ML21231A 187). The NRC staff notes that the Zion L TP dose modeling uses dose coefficients from FGR-11, which is based on ICRP-30.

The information described b elow for each of the resp onses to Spe cific Co n s iderati on 3 also wi ll be included in the TSD th at document s the survey results.

ZIONSOLUTIONS RESPONSE:

The DRP S ur vey Pl a n pro vides the a priori MD As for the d etectio n of DRPs that cou ld po se un accepta bl y hi gh risk to a future occ upant o n and near the surfac e. ZionSo l utions believe s that the a priori MD As de sc ribed in the DRP Survey Plan are adequate to address th e range of potential DRP s not prev io us ly d etected. It has bee n de signe d t o take into acco unt the range of radionuc lid e composi ti o n, activity, physical size, and c h e mi ca l compos iti o n of potential DRP s rem a inin g at the site. T hi s approach tak es into acco unt a ll p otenti a l DRPs regardless of origin.

As state d in the DRP Survey Plan, dose est im ates from the particl es that m ay remain at th e Zion site after the s urv ey is completed w ill be d oc umented in a TSD a nd su bmitt e d to the NRC along with the res ult s of the s urveys. T h e post-survey TSD will a l so includ e an a posteriori probabilistic MDA eva lu ation using the same param eters in id e nt ifying areas for further in vestigat ion.

NRC SPECIFIC CONSIDERATION 3b:

Scenarios that should be considered include inhalation, ingestion, and skin exposures to remaining discrete radioactive particles. For inhalation and ingestion, the anticipated particle size ranges should account for particle size change over the 1,000-year compliance period. For ingestion, the technical basis for selection of the fl value (fraction of ingested element absorbed

Page 63 o f96 Zi onSo lution s, LLC ZS - 2022 -0 l 0 A tt ac hm ent directly into the body fluids) should be provided, based on the chemical compositions of activated metal, activated bioshield concrete, and irradiated fuel fragments. For skin exposures,

the shallow dose equivalent and deep dose equivalent from discrete radioactive particle exp o sures to the skin for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> should be considered. The calculations should consider the ran g e o f cobalt-60 ( onl y ) di sc rete radioactive particle s, as well as the radionuclide mixes that comprise activated concrete from the bioshield and irradiated fuel fragments. VARSKfN Version 6.2. 1 s hould be used for the s e calculation s.

ZIONSOLUTIO N S RESPONSE:

T h e ex p os ur es fro m th e inh a lat io n, in ges ti o n, a nd s kin ex p os u re of t h e h y p oth e ti ca l DRP so urc e tenn h ave bee n assesse d as LLB P sce n a ri os du e t o th e ir low p ro ba bili ty of occ urre n ce. T reat in g th e low-p ro ba bil ity DRP ex p os ur e as a n LL BP sce n a ri o is co n s ist e nt w ith th e N R C - a ppro ve d app roac h use d in th e Z io n LTP fo r a ssess in g th e l ow -p ro ba bili ty sce n a ri o of a we ll driller co n tac tin g th e A ux ili a ry Buildin g d ra in s, w hi c h w a s a lso d es ig n a t e d as a n LL BP sce n a ri o. In acc o rda nce w it h NUREG -17 5 7, th e eva lu ati o n o f LL B P ex p os ur e sce n a ri os e n s u re s th at

" un acce pta bl y hi gh ri s k s wo uld not r es ult," but ar e not co n s id er e d co mpli anc e sce n ari os.

Accor din g ly, th e d ose fr o m t h e hy p oth eti ca l DRP s wi ll n ot be a dd ed to t h e Z io n co mplianc e d ose.

A n un ac c ep ta bl y hi g h ri s k is v iewe d as th at co rr es p ondin g t o th e publi c d ose lim it of 100 mr em /yea r TE DE w hich re p rese n ts a li fe tim e fa t a l can cer ri s k of a bo ut 4 x 10-3. SECY 0 46A a l so st at es th a t the fa t a l canc e r ri sk c orr esp o ndin g t o th e 2 5 mrem /yea r unr es trict e d use crit er ia is a n o rd e r of m ag nitud e lowe r a t 4 x 10 -4 a nd th at thi s ri sk is es tim a te d ass umin g a ri sk coe ffici e nt of 5xl 0-4 p e r re m and a 3 0- yea r lifetim e exp os ur e.

To ju st ify th e d es ig n a tion of t h e hy p oth e t ica l DRP exp os ure path way as a n LLBP sc en a ri o, th e p ro ba biliti es of DRP in g e s ti o n a nd inh a la ti o n ar e c o mpar e d t o th e pro b a bilit y of d r illin g int o th e A ux il ia r y Buildin g drain s, w hi c h wa s acce pte d by NRC as a n L L BP s c e n a ri o in th e Z io n LTP.

T h e p ro b abilit y of a drill c o n tac tin g th e A ux ili a ry Buildin g drain s i s 1.5x 10-3 fo r a s in g le we ll drill e d o n th e s it e as c a lcula ted by th e e qu ati o n be low.

E quati on 9 - Pr obability of Aux ilia ry Buildin g Drain Co nt act by Drillin g

SAdrain P dra in = A CZ W he re :

P dra in = p ro b a bilit y of dr ill c ont act in g A ux ilia ry Buildin g d ra in

SAdra in = p rojec te d s ur face ar ea of A ux ili ar y Buildin g d ra in s (9 6.2 m 2)

A c== a rea of co ntamin a t e d zo ne (6 4, 500 ni)

P age 64 o f 96 Z ionSolu tions, LLC ZS - 2022 - 0 l 0 Attac hm e n t Th e p ro b a bili ty of a fu t ur e s it e res id e nt in ges tin g o r inh a lin g a s in g le DRP at l. 6x I o*8 and l.7 x l 0*10, res p ec ti ve ly, is mu ch lo w e r th an drillin g int o an Au x ili a r y Buildin g drain. The p ro ba bilit y of a p ar t ic le in gest io n and inh a lat io n fr o m th e Z io n e nd s t a t e is ca lc ul a t e d u s in g th e eq ua ti o n b e low. T h e r es id e n t is ass um e d to occ up y th e site fo r a 30 -y ea r p e ri o d in a c co rdan ce w it h SE CY - 97 - 046A.

E qu a tio n JO-Proba bility of S in g le P a rti cle Inhalati on and In ges ti on 30 1R5

Wh e re:

P nRP = pro ba bilit y of in ges tin g o r inh a lin g o n e DRP

!Rs= so il m ass in ges ti o n rat e (18.3 g/y) o r inh a lat io n rat e 0.2 (g/y)

Ac== a rea of Z io n c o nta minat e d zo ne (6 4, 500 m 2)

l e== thi ckness of so il laye r affec t e d by DRP ( 0.304 8 m )

CFcm3/m3 = co nve rs io n fac tor (l.00 E+ 06 c m 3/m 3 )

ds = d e n s ity of so il ( 1.8 g /cm 3) (see LTP 5.8.4.4 )

3 0 = 3 0- y e a r li fe tim e ex p os ure p e ri o d t o th e ave r age m e mb e r of th e c r iti ca l g roup p e r SECY - 9 7-04 A Th e fi n a l p ro ba bili ty o f DRP inhalati o n a nd in ges ti o n exp os ur e is calc ul a t e d by multipl y in g th e hy p oth eti c al numb e r of DRP s es timat e d t o re m a in by th e s in g le DRP p ro ba bili ty. As d es crib e d in th e resp o n se to Sp ec ifi c Co n s ideration 3 c, 3 1 DRP s are es timated t o hy p o th e ti c all y remain. T h e fin a l li fe tim e p ro b a bili ty o f in ges tion o r inh a lati o n o f a DRP is th e refo r e 4.8 x l 0*7 and 5.2 x l o*9, res p ec ti v el y.

Th e probabilit y of a DRP b e in g depo s ited o n th e s kin durin g the li fe tim e o f a futur e s ite re s id e nt is l. 2x I0 *7, w hi c h is ca lcul a t e d u s ing th e equati o n b e low, ass umin g o n e DRP rem a in s on th e s ite.

T h e s in g le DRP p ro b a bili ty is multipli e d by 3 1, th e app rox imat e numb er of DRP s p roject e d t o hy p ot h eti ca ll y re m a in res ultin g in a fin a l li fe tim e p ro b a bili ty of 3.7xI0*6 th at a DRP w ill c ont ac t th e sk in of a fu t ure s ite r es id e nt. T h e d e rm a l d ep os iti o n p aram et e r s in th e e qu at io n a re fr o m th e E P A ' s Ri sk Assess ment Guid a nce for Sup e rfund.25

25 " Risk Assess m ent G u id ance fo r Su pe rfund Vo lu m e I : Hum an Hea lth Eva lu atio n Ma nu a l, Part E, Suppl e m e n ta l G ui dan ce for D er m a l Ri sk Assess m e nt," U.S. E n viro nm e nta l P ro tec ti o n Age ncy, EPA/540/R/99/005, E xhibit 3-5,

Jul y 2004.

P age 65 of96 ZionSolu tion s, LLC ZS - 2022 -010 Attach m e nt Equation 11 - Probabilit y of Single P article Skin D epositio n

PoRP M s kinTe

Wh ere:

P oR. P = li fe time probabilit y o f skin ex p os ure to a ss umin g o n e DRP pres e nt on s ite A cz = area of Z io n co nt a minat ed zone (64, 500 m 2) tcz = thicknes s of soi l lay e r affected by DRP (0.3048 m )

CF cm3/m3 = co n vers io n factor (1.00E + 06 c m 3/m 3) d s = density of soi l (1.8 g /cm 3)

T e= time that res id e nt occ upi es th e s ite (30 y)

M sk in = mass loadin g of so il on skin (g)

Where: M s kin = f s kin m ass l o ading eve nt£ f ev ent f re qu e n cy A f s oil C Fg /mgA skin fsk in mass loa din g eve nt = ma ss loadin g frequency ( 1 eve nt/ d )

Efeve nt frequency= fre qu e nc y of eve nt p er year (350 d/y )

Afso il = so il adhere nc e facto r fo r re s id e nt gar d e n e r (0.07 m g/cm 2)

CF g;mg = conversion factor (l.0 0 E -0 3 g /m g)

A skin= s kin s urface area (5, 700 c m 2)

The dose to the average memb er of th e cr itica l gro up fro m DRP expos ur e i s a lo w probabili ty,

o nc e in a li fe tim e eve nt, as compared to the ass um e d 30 - yea r life tim e expo s ure from di sp erse so u rce terms su c h as so il. Therefore, the dose (TE D E, CEDE, o r E D E) from the h ypot heti ca l DRP wi ll be multiplied by th e fa tal cancer risk coefficient app l ie d in SECY-9 7-04 6A, i.e., 5x10-4 per rem, a nd co mp are d to the risk of 4x10- 4 that repr esents the 25 mr e m /yea r unr estr icte d use criter io n. If the risks from the LLBP DRP ingestion and inhalation expos ure sce na r ios are be low 4x10- 4, they are not co n s id ered un acce ptab ly hi g h.

In order to provide a co mpr e h e n s iv e and thorough eva lu ation of th e potential d ose to future occupa nts from DRPs in the end state la nd areas, we have eva luat ed potential d oses assoc iated with particle s at the 5 0 th p ercentile a po s teriori MD As of t h e towed scan nin g array of 0.1 2 µ Ci Co - 60 a nd 0.41 µCi Cs-137. T h e 5 0th percentile MDA was c h ose n because it represents the median and most lik e ly d etectab le p art ic le act iv iti es that wo uld b e e nco untered a nd thus th e most lik e ly doses that wo uld result fro m exp os u re to DRP s.

The expos ur e pathways eva lu ated includ e:

Page 66 of 96 ZionSolutions, LLC ZS-2022-0 l 0 Attachment

1. Estimated particle sizes at the 50 th percentile MDAs, and potential doses from ingestion of large non-respirable particles with act ivit ies scaled to the 50 th percentile MD As to account for hard-to-detect radionuclides that may be present.

2. Fractionati o n of 50 t h percenti le particl e s to 1 µrn AMAD and calcu lated activities and inhalati o n d os e s from the s maller particle s.

3. Complete dissolution of the 50 t h percentile MDA particles and th e resulting localized distributed soil concentrations, and potential doses using newly calculated area factor s and DCGL EMCS for the nuclides of co ncern in the particles.

4. Potential sha ll ow, deep dose equiva lents, effective dose equivalents (EDE) for particles on the skin with a 24-hour expo s ure period at the scaled 50 th percenti le MDA activities.

DRP S ize Estimates Particle sizes are estimated for eac h of the DRP types that have been detected: activated steel,

activated concrete, and ir radiated fuel. ln addition, anticipated particles s izes accounti n g for changes in s ize over the 1,000-year compliance period have b een estimated.

Activated Steel A minimum DRP diameter, d e, for activated metal can be calcu lated using the highest activated source-term from decommissioning act ivities, wh ich is well represented by the activation calculations of the concentrations of the reactor vessel internals. 26 The table be low s umm arizes the Co-60 concentrations, C co-60, for the various reactor internals compone nt s for each of the two reactors as of January 1, 2021. This s hows that the highest concentrations are from the baffle plates in Unit 1 as 4.06E-02 Ci /cc or 4.06E + 10 pCi /cc.

26 WMG 07-046D-RE - 088, " Zion Units 1 and 2 Activation A nalysis and Component Characterization," January 2008.

Page 67 of96 ZionSolutions, LLC ZS-2022-010 Attachment Table 11 - Reac to r Internal Compone nt Activities Component Unit 1 C co -60 Unit 2 C c o-60 (Ci/cc) (Ci/cc)

Upper Core Plate 1. lSE-03 l.84E-05 Lower Co re Barrel 1.78 £ -0 3 1.73£-0 3 Therma l S hi e ld 2.60E-04 2.52E-04 Baffle Plate s 4.06 E -0 2 3. 98 E -0 2 Baffle For m ers 2.92E - 02 2.84 E -02 Lower Core P late l.03E - 02 l.0lE -0 2 Ba lance o f Lower s l.67E-04 l.64E-04 Vessel Wa ll 1.55E-06 9.S0E -08 Vesse l C lad 5.61E-05 5.48E -0 5

The maximum c oncentration fr o m the ab ov e tab le is for the Unit 1 baffle p late, which is used to estimate a mini mum DRP vo lum e, V, for DRP activ iti es co rr espo ndin g to the 50 th percentile of the a posteriori distribution for the probabilistic parameters fro m TSD 2 1-001 Rev. 2 us in g the fo ll owing:

Equation 12 - DRP Volume Corr esp onding to the SO'h Per centil e a post eriori Distribution V(cc) MDAso,co-6o(pCi)

Cco-6o(cc) pCi

Using the above, with th e Unit l baffle plate co nce ntrati on of 4.06E-02 Ci /cc, the DRP vo lum e for 50 t h percentile sca n MDA act iv ity (0. 12 µCi Co -60), the MD A is 2.90E -0 6 cc. I From this vo lum e, the DRP physical di ameter, de, can be estimated assum in g a spher ica l geometry using:

Eq uati on 13 - Volum e of a Sphere

V = ~nr 3 3

Rearranging yields:

Equation 14 - DRP Ph ysica l Diameter

Where:

V = the spherica l vo lum e of the DRP ba sed on the co ncentration in the base material (pC i/cc) and the activity of the DRP (pCi)

Page 68 of 96 ZionSolutions, LLC ZS-2022-010 Attac hment r = the radius of th e sph er ical vo lum e of the DRP d e= the physical di ameter of th e DRP

Using the above eq uati o n, the particle diameter fo r the 50 th percentile Co-60 MDA particle diameter is 124 µm.

The equation to calc ul ate aerody nami c eq ui va le nt diameter (da e) equiva le nt to AMAD for a di s tributio n of particl e s ize s weig ht ed by activ it y, from the phy s ical eq ui va le nt vo lum e di a m eter (de) below, is take n from Eq uat io n 2-1 o n page 2 - 2 in a report prep ared for the NRC.27

E quation 15 -Aerodynamic Equi valent Diam eter

Wh ere:

da e = the aerodynamic equivalent diam eter d e = th e equivalent volume diam ete r (physical diameter) of the DRP p = the density of the particle m ater ial 8 gl ee stee l, 2.35 gl ee act iva ted concrete, 10.9 7 gl ee uranium d iox id e

x = the partic le s h ape factor, u s u a ll y b e tv,1ee n 1 and 2. Typical va lu e of 1.5 is u se d for a spherical geometry

Therefore, r ea rran g in g thi s and solv in g for d e y ie ld s:

Equation 16 - Phy sica l Diam et er of 1 µm Parti cle 1 µm da e d, = ft

The sperica l volume of 1 µm particle, V(l µm d ae), is calculated u s in g the fo ll owing:

Eq uation 17 - Spherical Volum e of 1 pm Particl e

3 V(1µm d ae ) = 3 rr 2 4 (de)

Therefore, th e intact p articl e aero dy nami c e quiva le nt di a m e ter for an 8 gl ee den sity sphere with a

1. 5 s hap e factor for the 50 th percent i le is 28 7 µm, re sp ect ive ly. Thus, intact p art icl es d etected at th e MD As far exceed th e 10 µm respirable p art icl e thr es h o ld. Also, since the parti c le wo uld not lik ely be truly sp herical the m e dian aerodynamic diam eter co u ld be s ub sta ntiall y large r.

27 " Airbo rn e Particle Re s uspension and Inha lat ion Radiological Do se Es tim ation Fo ll ow in g Vo lcanic Eve nt s,"

prepared fo r U. S. uclear Regulatory C ommi ss ion, Co ntr ac t NRC- 02-07-006, September 2011.

Page 69 of96 ZionSolutions, LLC ZS-2022 - 010 Attachment The ICRP-30 lung model is based up on l µm AMAD partic les. The sp herical volume of 1 µm AMAD d ae activated stee l particle is 4.25E -1 4 cc. The vo lum es and correspo ndin gly the activities of th e 1 micron particles at the 50 th pe rcent il e Co-60 MDA (i.e., 2.90E-06 cc) wo ul d be reduced by a factor of 8.63E -09, resultin g in a Co -60 partic le activity of l.02E -0 3 pCi for an equi a lent volume diameter of I µm AMAD. The doses from inhalati o n of these partic les created by fractionation of larger particle s at the Co-60 MDAs would be at this activity level and the do es wou ld be insignificant. Thus, even if over time the activated metal particle s ize s are reduced to respirable particle s izes, th e dose from inhalation would be incon equential.

Activated Concrete Similar to the activated metal, the estimated partic le size of the activated concrete particle SO 124AEu is based on the hi g he s t concentration activated concrete detected in the under ves el durin g characterization (core B102106-CJFCCV -002) of 39 7 pCi l g E u-152 28. This sa mple was co ll ected b etween June 20 12 a nd January 2013 a nd is not decay-corrected for t h e purpose of this analysis. At a concentration of 397 pCi l g. the E u-154 activity (344,000 pCi) observed o n the SOJ 24AE u particle corresponds t o an 867 gram piece of activated concrete. Using a density of 2.35 glee, this is a 369 cc piece of concrete. This is an unreasonably large estimate of the s ize because it is ba se d on t h e highest Eu-152 pCi lg act iv ity observed in a co n crete core. T he core locat io n is from t he in core und er vesse l area floor, w hi ch is not necessarily the highest activated concrete present in t h e concrete surro undin g the reactor vesse l.

A more reasonable particle s ize estimate can be made by using the Co - 60 data. The hi g he st concentration of Co - 60 observed in the activated concrete characterization samples was 1.09 E+03 pC i/g in core B102110-CJFCCV-001 28. The Co-60 leve l in the particle was 30,000 pCi. At this activity leve l and ass umin g a density of2.35 gl ee the s ize of thi s particle is 27.5 grams or 11.7 cc. Assu min g a theoret ical particle was pre se nt with a Co - 60 act ivity eq u a l to the towed array scan MDA, the size of the particle wo uld be 183 grams or 78 cc.

Table 12 - Concre te Particle Size Analysis Co-6 0pCi 30,000 2.00E+0S

C o-60 S204AEu 50th Percentile Scan MDA

gr ams 2.75E+0l l.83E+02 cc 1. 17E+01 7.81E+01

Particles of this size are not respira bl e. A reductio n in the particle size wo uld produce a correspon din g reduct ion in the parti c le activ ity. As s uc h, a 1 µm AMAD particle fragme nt

28 ZionSolutions TSD 14-028, "Radiological C haracteri zat ion Report," Revi sion 0, December 20 I 4.

Page 70 of 96 Z ionSolution s, LLC ZS - 2022 -01 0 Attac hm e n t ge nerate d ove r tim e fr o m th e o ri g in a l p a rt ic les or co ncr et e pi eces is l ik e ly t o co ntai n minim a l activ ity.

Irradiated Fuel Par ticle For the fue l particle (S0126), th e m ass of Pu-239 is est imated fro m the re po rt e d activ ity (7,450 pCi) a lo n g wit h t h e sp ec i fic act iv ity of Pu - 239 of 6.2E l 0 pC i/g res ul t ing in a P u m ass of 1. 22E -

07 g. Us in g thi s Pu m ass, th e f ue l m ass ca n be es tim at ed us in g d ata fro m F ig ur e 2, w hich sh ows 5 kg P u-239 per to nn e of fuel at a two-year irra di at ion in terva l res u lting in a fue l mass of 2. 16E-0 5 g. Us in g t h e sa m e m eth o d o logy d esc rib ed above a nd acco un t in g fo r t h e U - 238 m ass to fu e l m ass rati o of0.94 1, thi s f ue l m ass c o rr es p onds to a ph ys ica l sph erica l di a m e ter of 155 µm a nd an aerody n am ic equiva lent d iameter, dac, of 420 ~* m AMAD us i ng a densi ty of 10.97 g/cc an d a shape facto r of 1.5, we l l a bove th e s ize co n s id e re d res p irab le.

Wh e n the S 01 26 radi o nuclid e mi x is sca le d to th e Cs - 13 7 Sca n M D As, th e fo llow in g P u-239 co nce n trat io n s, part ic le vo lum es and di amete rs res ul t.

Ta ble 13 - Cs-137 S can M DA Ir ra dia ted F u el Par t i cle Size

S0 12 6 @ Pu -239 Acti v ity Pu-239 U-238 U-238 Particle S phere MDAs (pCi) Ma s s (g ) SF M a ss (g) V olum e Diameter (d.) (c c) (µm )

Pu-239 50th 3.15£ + 04 5.08£-07 1.62£ -04 9.02£ -05 8.20£ -06 1. 76£+02 A 1 µm AMA D fue l p a rti c le has a sph eri ca l vo lum e of 2.65E -14 cc. T hu s, th e ac t iv ity of a 1 µm AMA D parti c le d er ive d fro m a parti c le at t he 50th p erce nti le Cs - 137 sca n MD A wo u ld be re du ce d b y a facto r of l.90E - 09.

DRP Inte rn al Dose A n a ly si s As di sc usse d in th e pri or sec ti on s, th e o nl y lik e ly inte rn a l d ose p a th way fr om th e id entified DRP s is fro m in ges ti o n s in ce t h e p art ic le s ize est im ate fo r eac h DRP ty pe is sub st an t ia ll y lar ge r than a res pi ra b le s ize limit o f 10 µm. T h i s int ern a l d ose a n a lys is is p e rfo rm e d fo r eac h of th e DRP t y p es id e n t ifie d to d ate (ac ti va t ed m eta l, ac ti vate d co n c r ete, a nd irr adi ated fue l).

Fo r eac h p a rti c le ty p e, we have ass um e d that eac h is best represe n ted b y th e m ost in so lub le fo rm s in ce th e p art icles h ave b ee n expose d t o weat h e rin g and h ave li ke ly beco m e sta bl e s in ce th e p ar ti cl e's c rea ti o n. A lso, th e re a pp ea r s to be n o ava il a bl e d at a w it hi n t h e lit era tur e for a bso rpti o n of ra di onucl id es wi th in th e G I t ra c t fo r activate d p art ic les (i.e., co ncrete a nd stee l) bu t it is reaso n a bl e to expec t t hat thi s a bso rpti o n wil l be ve ry low. H owever, there is so m e d at a for irrad iate d fue l frag m ent s as di sc u sse d in m ore d et a il be low.

Therefo re, to represe nt t hese in so lub le st ates, we h ave se lect e d fo rm s wit h th e lowes t va lu e of th e para m et e r th at represe n ts a bso rp t io n from t h e G I t ract (a lim e ntary trac t ) t o th e bl oo d stream fo ll owi n g a hy p ot h eti ca l in gest io n eve nt. I n eac h case, th e ca lcul at e d inte rn a l dose fo ll ows th e m et h o d o logy from ICRP -3 0, t h e bas is of th e m eth o d s rep rese nt e d in 10 CF R 2 0, in c ludin g th e

P age 71 of 96 Z ionSolution s, LLC ZS - 202 2 - 010 Attac hm e nt ti ss ue w e igh t ing fac t o r s. T h e in ges ti o n int ern a l d oses ar e calc ul at e d u s in g IMBA Pro fess io n a l Plu s V er s io n 4.1.11 u s in g p ar a m e ter s fr o m I C RP-26 /3 0 or directl y fro m Fed e ral Guida n ce R e po rt N o. 11 (FG Rl 1) as no t e d in e ach sec ti o n.

Activat ed Meta l Parti cle Activiti es and Dos es For the firs t p art of thi s a n a lysi s, we h ave co n s id e r ed parti c le numb er S O 124 s in ce it represe n ts t he part ic le w ith th e hi g h es t re p o rt e d act iv ity of Co -60 fo und b y ORI S. In o rd er to acco unt for t he rema ind e r of t h e ac ti vat ion ra di o nu cl id es t ha t were n ot m eas ured in t h e p art ic le assess m e n t, we h ave sca le d th ese to Co - 60 fr om t h e m ean co mp o n e nt a cti v ity of th e c a lcul ati o n s of t h e reacto r int e rnal s ac ti v ati o n. In additi o n, we th e n sc a le d th e Co - 6 0 activ it ies t o t h e 50 th p erc e ntil e of t h e DRP sca n M D A di stributi o n. T he in ges ti o n d o se ca lc u lati o n s fo r thi s p a rti c le ar e sh own in th e ta b les b e low. Fo r th is p a rti c le ty p e we ha ve use d th e lowes t /, va lu e a nd it s co rr es p o ndin g d ose co nve r s io n fac t o r fr o m FG Rl 1.

Ta bl e 14 - Acti va ted Metal DRP S can MDA Acti vity Activati o n A cti v i ty Particle Activi ty Nuclide Acti v ity Ratio to Scaled to 50 th Calculation for Co-60 P e rcentile MDA Ul (Ci) (pCi)

H-3 2.53E+ 02 2.53E -0 3 3.0 4E+ 0 2 C-14 3.59E + 02 3.59E -03 4.3 1E+ 0 2 M n -54 2.85 E + 0 l 2. 8 5E- 0 4 3.42E + 0l Fe-55 7. 15 E+ 0 3 7. 14E- 0 2 8. 57 E+ 03 Co - 60 l.0 0E + 0S l.00E+00 l.20E + 0 S Ni-59 l. 66E+ 0 3 l.66E - 02 l.99E+ 0 3 N i-63 2.27E + 0 5 2.27E+00 2.72E + 0 S Nb-94 5. 54 E+00 5. 53E -0 5 6.64E+ 00 Tc-99 l.18 E+ 0 0 l.1 7E- 05 l.40E+ 00

P age 72 of 96 ZionSo lutions, LLC ZS-2022 - 0 I 0 Attachme n t Table 15 -Activated Metal DRP Sca n MDA Dose FGR 11 I n gest ion Par t icle Ingestion Dose Nuclide FGR ll/1 Dose Fac t o r Eq u ivalent Scaled to 50 th (mrem /pCi) Percentile MDA (mrem)

H-3 I.00E+00 6.40£ -08 l.91E - 05 C-1 4 l.00E +00 2.09£-06 8.84£ -0 4 Mn-54 l.00 E-01 2.77£ -06 9.32E-05 Fe-55 I.00E-01 6.07E-07 5.llE-03 Co -60 5.00E-02 1.02£ -05 l.20E+0 0 Ni -59 5.00E-02 2.l0E-07 4. l lE-04 Ni-63 5.00E-02 5.77£-07 l.54E-0l Nb-94 l.00E-02 7. 14E-06 4.66E-05 Tc-99 8. 00E-01 l.46E-06 2.02E-06 Total 1.36E+00

One particle was fou nd during the DRP survey. T hi s DRP (Sample IA81Al04P) was ana lyzed by gamma spectroscopy at GEL and had a Co - 60 activ ity of 0. 16 7 µCi. The calc ul ated dose from inge stio n of this DRP is sh own in the table below.

Table 16 - DRP IASIAJ 04P In ges tion Dose FGRll Ingest ion Co-60 I n gestion Nuclide Dose Sc aling Dose Factor, Factor (mrem) mrem/pCi H -3 6.40£-08 2.53£ - 03 2.70£-05 C-14 2.09£-06 3.59E-03 1.25£-03 Mn - 54 2.77£-06 2.85£ - 04 l.32E-04 Fe-55 6.07E-07 7.14E-02 7.24E-03 Co-60 1.02E-05 l.00E+00 l.70E +00 Ni-59 2.l0E-07 l.66E-02 5.82E-04 Ni-63 5.77E-07 2.27E+00 2.19E-0l Nb -94 7. 14E-06 5.53£ -05 6.60E-05 Tc-99 1.46£ -06 l.17E -05 2.86E-06 Total 1.93E+00

Activated Concrete

The activity in a piece of activated concrete at the 50th percent il e of the Co-60 DRP scan MDA is shown below. The Co-60 sca lin g factors for Ba-133, Eu -1 52, and Eu-154 were derived from the results of Sample S204EU. The remaining nuclides have been scale d to Co-60 using the

Page 73 of96 ZionSolutions, LLC ZS-2022-010 Attachment activated metal sca lin g factors described above. The basis for using the activated meta l sca lin g factors is the assumpt ion that these nuclid es are from the activation ofre bar in the conc rete. We then sca led the Co-60 activities to the 50 th perce n t il e of the DRP scan MDA. The ingestion dose calculatio n s for this particle as shown in the tables be low. For this particle type, we h ave used the lowest_[! value and it s corre spondin g do se conver s ion factor from FGRl 1.

Table 17 -Activated Co n cre t e Particle Activity

Nuclide Scaled to 50 th Activity Ratio to Particle Activity Co-60 Percentile MDA (pCi)

H-3 2.53E-03 3. 04 E+02 C-14 3.59E -03 4.31E + 02 Mn-54 2.85E-04 3.42E + 0l Fe -5 5 7.14E-02 8.57E + 03 Co-60 l.00E+00 l.20E+05 Ni-59 1.66E-02 1.99£+03 N i-63 2.27E + 00 2.72£+05 Nb-94 5.53E-05 6.64E+00 Tc-99 1.17E-05 l.40E+00 Ba-13 3 5.07E-02 6.08E+03 Eu-152 1.1 SE+0l l.38E+06 Eu-154 5.40E-01 6.48E+04

Table 18 - Activated Concre te Particl e Inge stion Dose Particle Ingestion Dose FGR 11 Ingestion Equivalent Scaled to Nuclide FGRll/1 Dose Factor Co-60 (mrem/pCi) 50 th Percentile MDA (mrem)

H-3 l.00E+00 6.40E-08 1.91E-05 j C-14 l.00E + 00 2.09E-06 8.84E-04 Mn -54 1.00E-01 2.77E-06 9.32E - 05 Fe-55 1.00E-01 6.07E-07 5. 1 JE-03 Co-60 5.00E-02 l.02E - 05 l.20E+00 Ni-59 5.00E -0 2 2. 10 E -07 4.llE-04 Ni-63 5.00E-02 5.77E -0 7 1.54E-01 Nb-94 l.00E-02 7. 14E-06 4.66E -0 5 Tc-99 8.00E-01 l.46E-06 2.02E -06 Ba-133 1.00E-01 3.60E - 05 2.03E -0 2 Eu-152 l.00E-03 6.48E-06 8.78E+00 Eu-154 l.00E-03 9.SSE-06 6.07E-0l Total 1.08E+0l

Page 74 of 96 ZionSolutions, LLC ZS-2022-0 l 0 Attachment Irradiated Fuel Activ ity and In gesti on Dose For thi s particle type, we id e ntified two so urces of estimating absorption from th e GI (i.e.,

alimentary) tra ct. The fir st is from ICRP-1 3 7 wh ich pro v ide s the following :

In Publi catio n 30 ( l CRP, 1979), a n a bsorpti on va lu e of 2XI 0-4 wa s recommended o n th e basis of th e st ud y of Mal e t skos et al. (1969). ln Publi catio n s 67 (lCRP, 199 3) and 69 (ICRP, 1995a), becau se s imil ar va lu es have b ee n obta in ed in more recent human s tudi es on the absorption of plut o nium, americium, neptunium, and c urium, a ge neral absorptio n va lu e of sx10-4 w as adopted for dietar y int ake by ad ult s for all actinides other than uranium. In Publication 68 (1994b ), a va lue of 2X 1 o-4 was applied to ox id es and hy droxide s, w ith 5X10- 4 app li e d fo r a ll ot h e r c h emical forms. An fA va lu e of 5X l 0- 4 is a d opted here for all chemical forms.

However, this section oflCRP - 137 doe s no t provide direct gu id ance for ingestion expos ure t o irr ad iated fuel particles for the act inid es. ICRP-13 7 doe s provide an in-depth di scussion on Cs-137 in irradiat e d fu e l particl es. Tab le 6.2 s hows that for in ges tion of a ll forms of Cs, ex cept irradiated fuel, the/a va lu e (same a sjj for ICRP-30) is 1.0, but for irr a diated fuel, the va lue is 0.1 or a factor of 10 reduction. Since the di sc u ss ion on th e actinides va l ue offa in I C RP-137 doe s not include irradi ated fuel particles, but is in c luded for Cs - 13 7, a very soluble e le m ent, using thi s factor of 10 reduction is app li cab le to the /a va lu e of 5X10-4 for a final va lu e of 5X1 o -5.

This va lue is consiste nt with the work reported in Environment H ealth P ersp ectives 29 wit h a va lu e of 3X 10-5 for the fractional absorption by ingestion of radionuclides within irradiated fu e l fragments. Additiona ll y, thi s reference states, in regard to inge stion absorpt ion of e leme nt s within a fuel fra g ment: "... fis s ion product s in the fused particulate form renders them v irtuall y inert in m etabolic terms and the radionuclides are not metabolized along biolo g ical pathways characteristic for the elementar y form."

Therefore, in this internal do se analysis we used a value for jj of SX 10-5 for the actinides. We applied a reduction factor of 10 in the lowe stjj va lu es li sted in FGRl 1 for the other radion uclid es identified in thi s particle except for Sr-90 and Eu -1 55, for whic h the lowestjj va lue from FGRll is u sed. It is likel y that thejj va lu e of sx10-5 applies to all radionuclides contained within the fuel DRP ; h owever, thi s approach introduces a conservative margin int o the d ose calc ul ation resulting in a higher CED E than wou ld otherwise be calc ulat ed. We consider thi s approach to be appropriat e and conservative for th e h y pothetical d oses s h own below for thi s

29 Environm ental H ealth P ersp ec tiv es, Re v iew, Vo lume 10 3, No. 10, October 1995, p. 920 - 934 : " Bi ok ineti cs of Nuclear F ue l Com pounds a nd Biologica l Effec ts of onunifonn R adiati on," Sakari Lang (Department of E nviro nm e nt a l Scie nces, U ni versity ofK uopi o, Kuo pi o, F inland ), Krist in a Servomaa (Departmen t of Re search,

Fi nni sh Ce ntre for Radiation and Nu clear Safety, Hels inki, F inl and), Ve li-Matte Kosma (Department of Pathol ogy,

U ni vers ity ofKuopio, Kuop io, Finland), and Tapio R yto maa (Finnish Ce ntr e for Radiation and N ucl ea r Safety).

Page 75 of96 ZionSolutions, LLC ZS-2022-010 Attac hment fu e l particle s ince it appears that anfi value of zero ma y actua ll y apply to s uch an expos ure,

which wou ld further lower the calcu lated CEDE.

The ingest ion d ose from this particle was calcu lated us in g IMBA for the fI values shown in the table be low a lo ng w ith th e so urce of th e/I, th e C s -] 37 sca lin g factor, a nd th e CEDE us in g the ICRP - 26 /30 ti ss ue we ig htin g factors for the 50 th percentile of th e MDA d is tributi o n for Cs-137.

The inge stion d ose of the recovered fue l DRP, which containted.098 µ C i of Cs-13 7, is 14 mrem as s hown in the tab le be low.

Tabl e 19-Fuel Particl e Ing estion Dose S0126 N uclid e p C i /1 - So urc e -- In gesti on Dose (mr e m)

E u-155 838 0.001 FGRll 9.40E-04 Am - 24 1 79900 0.00005 ICRP 137 m o difi ed l.24 E+0 l C m-244 14800 0.00005 l CRP 137 modi fied 2.63E-01 Cs -137 98900 0. 1 ICRP 137 4.53E-01 Np-237 3.9 0.00005 ICRP 137 modifi ed 6.14E-05 Pu-238 26188 0.0 0005 ICRP 137 modified 4.41E-0l Pu -239 7540 0.00005 ICRP 137 m odifi ed l.19 E -0l Sr-90 157043 0.01 FGRl 1 4.53E -0l Tota l 385212.9 1.42E+0l

Tab le 20 - Irradiat ed Fue l Particle at Scan MDA Activities Particle Activity Radionuclide Activit y Ratio Scaled to 50 t h to Cs-137 Percentile MD A (pCi)

E u-155 8.47 E -03 3.47E+03 Am-241 8.08E-0l 3.31E+05 Cm-244 l.S0E-01 6. 15 E+04 Cs-137 l.00E + 00 4. 10E+05 Np-237 3.94E-05 l.62E+0l Pu-238 2.65E-01 l.09 E+05 Pu-239 7.62E-02 3.12E+04 Sr-90 l.59E+ 00 6.52E+05

Page 76 of96 ZionSolutions, LLC ZS-2O22-O1O Attachme nt Tabl e 21 - I rrad iat ed F u el Particle at Scan MDA In gestion Dose Particle Ingestion Radionuclide /1 Source of/, CEDE Scaled to 50 th Percentile MDA(mrem)

Eu-1 55 1.00E-03 FGRII 3.91E -0 3 Am-241 5.00E-05 ICRP 137 modifi ed 5.l 8E+0I Cm-244 5.00E -0 5 JCRP 137 modified 1.l0 E+00 Cs - 137 l.00E - 01 ICRP 137 l.89E+00 Np-237 5.00E-05 ICRP 137 modified 2.55E - 04 Pu-238 5.00E-05 ICRP 137 modified l.83E+O0 Pu-239 5.00E -05 ICRP 137 m odified 4.95E -01 Sr-90 1.0 0E- 02 FGRll l.89E+00 Total 5.90E+0l

Irradiated Fuel DRP Reduced Size over 1,000 years It is not possible to eva lu ate a rate at wh ich particle sizes may c hange over the 1,OOO-year period because there is limited dat a o n how stainless stee l, concrete, and irradiated fuel particle sizes change with time. Size changes a lso depend on the natural processes such as weathering and corros ion, and site use suc h as gr indin g or pulverization from h eavy equ ipm ent. The ICRP internal dose models are ba sed on l µm AMAD.

ZionSolutions cons id ered the potent ial for a partic le that has been reduced in size over t im e and calculated th e pote nt ia l dose from the SO 126 fue l particl e that h ad been size-reduced to a respirab le size. To do so, we eval u ate d the dose impact from a fuel particle that was red uc ed in s ize to 1 µm AMAD over time. The sp herical phys ical vo lume of the size-reduced partic le is calculated to be 2.65E -1 4 cc, as compared to the 155 µm part icle volume of2.O9E-O6 cc. The ratio of these volumes (l.35E - O8) wo uld also represent the ratio of the act ivities for particle SO 126 to a hy pothetical 1 µm dae particle, res ultin g in a Cs -1 3 7 activity of 1.33E-O3 pCi for the 1

µm partic le. The sca led mix and estimated dose from inhalation of a 1 µm d ae particle is 5.26E O5 mrem as summarized in the fo ll owing table.

Page 77 of96 ZionSolutions, LLC ZS-2022-010 Attachment Table 22 - 1 µm AMAD S0J 26 I rradia ted Fu el Particle Activiti es and Dos es Radi o nuclide A cti v ity (p Original Part icle 1 µmA MAD Inhalation Ci) Particle Activity TEDE (mr e m) Ci)

Eu -1 55 8.3 8E+02 1.1 3 E-05 l.25E-10 Am-241 7.99E + 04 1. 08 E -0 3 3.7 1£-05 Cm - 244 1.48 E+04 1.99 E-04 4.68£ -0 6 Cs-137 9.89E + 04 1. 33 E-03 9.08£-08 Np -237 3.90E+00 5.26 E-08 9.66£-10 Pu-238 2.62E + 04 3.53 E-04 8.0JE-06 Pu-239 7.54E+03 1.02 E-04 2. l J E-0 6 Sr-90 l.5 7E+05 2. 12 E-03 5.90£-07 To ta t 5.26E - 05

Doses fr o m Co m p lete Di sso luti o n o f Pa r ti cl es D oses were a lso eva lu ated for comp lete di sso l ution of part ic les over time into d istrib uted re s idual radioactivity in soi l ove r area s of 0.01, 0. 1, and 1 m 2 and at so i l depths of 15 cm deep us in g Surface Area Factors and DCGL EMCS from th e Zion LTP Chapter 6.11. Surface Area Factors for all the activated meta l nuc lid es and the nuclide identified in DRP S204AEu and S0126 a long with a so il den sity of 1.8 g/cc was used t o ca lculate the di lution ma ss of the so il within these areas. The particle activities in pCi were divided by the masses associated with areas of 0.01, 0.1, and 1 m 2 to calculate the d istributed contaminat ion soil conce n tration in pCi /g. The result s are shown below. This analysis t a ke s no credit for radioactive decay and is th u s very con serv ative s ince comp lete disso lu t ion wou ld li ke ly occur over man y years, if at all.

Tab le 23 -Activat ed Metal DRP Dissol u tion Dose Activated Metal 50th Percentile Co-60MDA CEDE mrem) ---<---i 0.01 2.l0E-03 --+------

0. l 2.1 0E-04 --+---------i 1 2. l0 E-0 5 ---'

Tabl e 24 -Activat ed Concrete DRP Dis so lution Dose Activat ed Are Concrete 50 th a Percentile Co-(m 2 ) 60MDACEDE mrem 0.0 1 1.40£ -0 2 0. 1 1.40£-0 3 1 l.40 E -04

Pa ge 78 of96 ZionSolutions, LLC ZS-2022-010 Attachment

Table 25 - Fuel DRP Dissolution Dose Irradiated Fuel Area 50 th Percentile (m2) Cs-137 MDA CEDE (mrem) 0.01 3.41E-03 0. 1 2.06E-04 1 l.89E-05

DRP External Doses Varskin Version 6.2.1 was used to calculate ski n and deep dose (SDE and DDE). However, the 25 mremlyear do se cr iterion in 10 CFR 20 Subpart E app li es to TEOE, not skin dose, and therefore direct comparison of SDE and ODE to the 25 mrem l year criterion is not appropriate.

To allow comparison of SDE to the 25 mrem l year dose limit, the SDE was multiplied by a risk factor to ca lculate fata l cancer risk and compared to the risk corresponding to the 25 mremlyear TEDE criterion as provided in SECY-97-046A, w hi ch is 4xI0*4 ly. The fata l can cer risk factor applied to the SDE dose is from the 2002 Fina l Rule for Revision of the Skin Dose Lim it 30. The risk factor from DRP SDE exposure is given as 6.6x10*101rem. To compare the DDE ski n dose to the 25 mrem l year criter ion, the ODE co uld be multipli ed by the skin tissue weighting factor of 0.01. However, this factor is not u sed in the DDE d oses reported below. This is a highly conservat ive approac h given that th e exposure from DRPs are assumed to be limit ed to a 10 cm 2 area as opposed to the e n tire skin s ur face area.

Two types of DRPs were evaluated, activated m eta l and irradiated fuel, usi ng the 50 th percentile of the Co-60 and Cs -137 scan MDA di str ibutio n s, respectively. For each of the activit ie s, the equivalent vo lum e diameter, de, was calculated as d escribed above. This diameter for a spher ica l particle was used in Varskin as the variab le that accounts for the self-atten u ation of beta particles within eac h DRP. A lso, for the act ivated metal DRPs, on ly Co - 60 was u sed si nce this nuclide c learly dominates the activity profile. Th e particle equiva lent vo lum e diameter is 124 µm with a density of 8 glee. For this particle, the associate d Co-60 act ivity is 0. 12 µCi and the SDE and DDE rates are 9.08 and 0.61 mrad per hour, respectively, corresponding to 24-hour doses of 218 and 14.6 mrad.

For the fuel DRP, the 50 th percentile particle diameter is 176 µm and the density is I 0.97 gl ee.

Only Sr-90 and Cs - 13 7 are included in the ca lc ul ations since the alpha em itt ers would make an insignificant contributio n to SDE and DDE. Varskin includes the doses from progeny nuclides.

Therefore, the calcu lated dose includes the contri buti on from Y-90. Last ly, the calcu lated dose rates are converted to a total dose for a 24-hour period as provided in the table below.

3° Final Ru le, Re vision of the Skin D ose Limit, 67 FR 16298, Apri l 5, 2002.

Page 79 of96 ZionSolutions, LLC ZS-2022-010 Attachment

Table 26 - Irradiated Fue l Parti cle External Doses

SO' h Percentile SO' h SDE Rate 24-hr SDE 24-hr DDE so th DDE Nuclide Activity (µCi) (mrad/hr) Rate (mrad) (mrad)

(mrad/hr)

Sr-90 6.52E-01 5.44E+02 5.3 lE-02 1.31E+04 1.3 lE + 00 Cs -I 37 4.1 0E-01 2.79E+02 6.3 lE-01 6.72E+03 4.32E+00 Total 1.06E+00 8.25E+02 6.84 E -01 1.98E+04 5.62E+00 SOE Risk of Fatal Cancer/year l.l9E-08 As s hown above, the risks of a fatal cancer at the calculated 24-hour SD Es are well below the 4.00E-04 /year that is commensurate with the 25 mrem /year site release criteria.

To better evaluate the dose relative to the 25 mrem /year site release criteria, ZionSolutions used EPRI guidance for calculating a DRP Effective Dose Equivalent. 3 1 This approach, authorized by the NRC in RlS-2003-04,32 was used to calculate the worst-case effective dose equivalents for Co-60 and Cs-13 7 at the 50 th percenti le MD As.

The NRC issued RIS-2003-04 to provide guidance regarding the use of EDE in place of DDE

"... in showing compliance with regulatory requirements." The RIS goes on to state:

Licensees are encouraged to use the effective dose equivalent in place of the DDE in all situations that do not involve direct monitoring of externa l exposures using personnel dosimetry. Such situations include, but are not limited to : [... ] (2) calculating doses from contaminated soils and buildings ; [... ] (5) making calcu lations in connection with li cense termination and release of sites; (6) assessing doses resulting from localized skin contaminations...

The EPRI methodology is useful because it provides a more accurate method for calculating dose from DRP exposures. In particular, the EPRl data show that dose can vary dependent upon the location of the DRP on the body. For both Cs-137 and Co-60, the highest dose EDE conversion factors are for a particle located in the center chest area at 11.904 rem/hr per Ci for Cs-13 7 and 48.631 rem/hr per Ci for Co-60.

Using the Cs-137 and Co-60 EDE dose conversion factors, the EDE for particles at the 50 th percentile a posteriori MDAs are calculated and provided in the table below.

3 1 " Implementing the EPRI Effective Dose Equivalent (EDE) Methodology for Discrete Radioactive Particle s on the Skin," Electric Power Re se arch Institut e, EPRI 100282 3, October 2004.

32 "Us e Of The Effective Dose Equivalent In Place Of The Deep Dose Equivalent In Dose Assessments," U.S.

uclear Regulatory Com mis s ion, Regulatory Issue Summary (RIS ) 2003-04, February 13, 2003.

Page 80 of96 ZionSolutions, LLC ZS - 2022-010 Attachment Table 27 - 50'h Percentile a posterio ri EDE a

posteriori a Max mrem/24 50 th posteriori rem/hr hr percentile 50 th EDE MDA percentile (pCi) MDA(Ci) 50th % Co-60 Scan MDA 0.12 l.20E-07 5.74E-06 l.37E-0l 50th % Cs -1 37 Scan MDA 0.41 4. l0E-07 4.91E-06 l.18E-0l

The effective dose equ ivalents from a particle on the skin are we ll below the li cense termination criteria.

Expectation Doses A risk -b ased approach was used to ca lcu late the potential dose from a DRP hypothetically remaining at the s it e. The approac h fo ll ows that approved by the Commission for the termination ofthe Sh e lwe ll license (SECY-98-117), in w hi c h thou sa nds of residual DRPs were estimated to remain at li ce nse termination. T h e ri sk from particles in the so il was est im ated by determining the annua l expectation d ose. T he expectation dose is calcu lated by multiplying the probability of encounter in g, inhaling or ingesting a particle in a given year by the dose from the particle.

The probabi lit ies for particle ingestion, inhalation and sk in adherence were calculated at the beginning of this response. Mu ltip ly in g these probabilities by the doses for the vario u s sce n arios presented earl ier yie ld s the expectat io n doses shown in the following table.

The expectation dose for the doses calculated above are summarized below. The highest annual expectation dose for the 24-hr ski n d ose fuel particle SDE is 2.64E-03 mrem ; h owever, the corresponding ann ua l E D E expectat io n d ose is l. 57E-08 mrem.

Page 81 of96 ZionSolution s, LLC ZS - 2022 -010 Attachme nt

Tab le 28 - Expec ta ti on Doses Annual Dose Calculation Case Expectation Dose (mrem)

In ges tion Activated Meta l at 50 th percenti le 2. 18 E- 08 In gest i on Act iva ted Conc re te at 50th l.72E -07 percenti le I nge s ti o n F ue l Parti cle at 50 th perc e ntil e 9.43E-07 Jn gestion o f 0. 167 µCi Co-60 Particle 3.09E - 08 In ges tion of SO 126 F ue l Particl e 2.27E -07 Inh al at io n of 1 µm F uel P art ic le 9.12E-l 5 F ue l Partic le 24 -h o ur SDE 2.64E -03 Fuel Particle 24 -h o ur DD E 7.49E -07 E D E Act ivated M etal at 50th perc en tile 1.83E -08 E DE Fu e l at 50th percent il e 1.57E -08

NRC SPECIFIC CONSIDERATION 3c:

Consider updatin g the previous estimate of the number of discrete radioactive particles that may remain after the survey and collection activities are completed, which was based on the presence of one particle in every 50 centimeters (diameter) of the land surface (see the licensee ' s response to RAI-11 d in the letter dated February 10, 2021 (ADAMS Accession No. ML21067 A225). The estimate of the number of particles should consider the potential for discrete radioactive particles remaining below the surface and should consider the likely location of the particles given their o rigin and transport mechanisms (see RAI-1 in the NRC letter dated August 19, 2021 (ADAMS Accession No. ML2 l 23 I A 187).

ZIONSOLUTIONS RESPONSE:

A ll of the DRP s id ent ifi ed during the scan s u rvey a nd vo lum etric sampling were remediated.

There w ill be n o known DRP so urc e term remainin g. An esti m ate of the number of DRP s th at ma y re main is h y p oth etical. The most reaso nable meth o d for m ak in g an est im ate of the numb er of DRP s that h y potheticall y m ay remain i to u se the resu lts of the can s u rvey s. T h e result s of the vo lum etric sampling cou ld be u se d but the pre se n ce/absence te s t u e d in s urvey d es ig n provides o nl y an upper-boundin g est im ate of DRP s that co uld remain, wh ic h is unrealistic.

The number of unidentified DRPs that could h y p oth et ica ll y remain wi ll be calculated by conservat iv e ly assum in g that a ll of th e DRP s id e n tified during th e scan s urve y were contained in a 1.0 cm laye r of so il, regardle ss of the actua l depth at w hich the y were fou nd, and that the ran ge of DRP radionuclide activities and mixtur es identified is representativ e of the DRP s that co uld h y p o theticall y remai n. In addit io n, the h ypothet ical DRP s are ass um e d to b e lim ited to the fir st

Page 82 of 96 ZionSolutions, LLC ZS-2022 -0 l 0 Attachment 30.5 cm (1 foot) la ye r of so il. Give n these ass umpti ons, the esti ma te of the numb er of DRP s that cou ld hy p oth et ica ll y re m a in was mad e by multipl y in g the numb er of DRPs id entifie d durin g the scan s urvey ( i.e., o ne) by 30.5. Acco rdin gly, the h ypothetica l numb er of particle s projec t e d to remain on the site is 3 1 (30.5 x 1).

The lik e ly loca ti ons of th e particles, i.e., those loca ti on w h ere DRP h ypo th e ti ca ll y re mainin g wou ld be mo s t li ke ly to be found, we re co n si dered in identif y in g areas that were included in th e DRP Survey Plan. The m ethodo lo gy does not ascr ib e location within that area ; rather, it estimates the numb er that could remai n anywhere w ithin that area.

NRC SPECIFIC CONSIDERATION 4:

The revised survey plan, if developed, should consider the following information for addressing the s ur vey area coverage during a future survey:

NRC SPECIFIC CONSIDERATION 4a:

A de sc ription of the areas surveyed and the rationale for not performing additional surveys of specific site areas. The rationale should consider information for any areas not surveyed previousl y, as well as relevant infom1ation from the licensee ' s RAI responses to the NRC letter dated August 19, 2021 (ADAMS Accession No. ML21231Al87).

ZIONSOLUTIONS RESPONSE :

Within the DRP Survey Plan, ZionSolutions ta rgeted 36 s urvey un its that had the potentia l to contain DRP s. In determining w hat s urvey unit s to tar get, Z ionSolutions se lected s urvey unit s :

w h ere clean concrete demo liti on debri s (CCDD) was temporaril y staged or transported through after comp leti on of FSS

w h ere waste loadout areas resided

with areas of e levated activ ity id entifie d by ORISE durin g the Ap ril 2021 inspection survey

that were adjacent to C lass 1 survey unit s (e.g., s urvey unit s 10 2 14, 10 2 13, 10212) where particles or e levated areas had been previousl y identifie d The rationa le for s urve y unit s not included in the DRP Survey Plan includes a combinat ion of the following:

Based on Z ionSo lutions assessment of the so u rce a nd transport of the DRP s that h ave been identified, th e survey unit was not expected to co n tain DRPs.

The s urvey unit had n o hi story of DRPs.

FSS was performed in the s u rvey unit w ith no identificat ion of DRPs.

Page 83 of9 6 ZionSolutions, LLC ZS-2022-010 Attachment

ORJSE performed an FSS confirmatory s urvey or ot her independent verificatio n s u rvey in the survey unit w ith n o identific at io n of DRPs.

S ur veys performed during final si te grad in g did not identi fy DRPs.

NRC SPECIFIC CONSIDERATION 4b:

The scan coverage for each of the survey units and whether survey unit coverage will increase if a discrete radioactive particle is detect e d in a survey unit.

ZIONSOLUTJONS RESPONSE:

In the eve nt that a DRP is d etecte d, a dj acent s ur vey units wi ll be added to the survey pl a n unless a lr eady included or oth er considerat io n s obv iate the need for expanding the survey area. In that event, the overriding co n s id erations wi ll be documented. Scan coverage is addressed in the DRP Survey Plan.

NRC SPECIFIC CONSIDERATION 5:

The results of the survey and calculations should be submitted to the NRC. The licensee should provide a commitment to share the survey results with the NRC staff in the form of an FSS Record after the surveys and calculations have been completed. The result of the survey should include, as a minimum, the following information consistent with the considerations described in this RAI :

NRC SPECIFIC CONSIDERATION Sa:

The number of discrete radioactive particles detected during the licensee 's survey activities and their location.

ZIONSOLUTJONS RESPONSE:

One DRP contain in g 1.60 µCi of Co-60 was detected during the DRP S urvey. The particle was located in SU 10221D.

The comp lete results of the survey and calculations will be submi tted to the NRC in a TSD up on completion of the work described in the DRP Survey Plan.

NRC SPECIFIC CONSIDERATION Sb:

The radionuclide composition and activity of the collected particle s, along with a description of the laboratory analyses performed Particles collected during the survey should be analyzed by an offsite laboratory for their radionuclide composition. This information is necessary given the discovery of unexpected particles of initially undetermined origin and radiological composition during the April 2021 survey.

Page 84 of96 Z ionSoluti o ns, LLC ZS - 2022 - 0 10 Attac hm e nt ZIONSOLUTIONS RESPONSE:

N o Cs -1 3 7 p a rt icl es we re id e ntifi e d durin g th e s urv ey. T he DRP fo und durin g th e s urve y w as se n t to GEL la bo ra t o ri es fo r gamma sp ec t rosco p y an a lys is. Th e o nl y ga mm a e mittin g nuclid e d etecte d was Co - 60. Jn a dditi o n, d ose ca lc ul a ti o n fo r ac t ivate d tee l ca le d th e HTD nu c lid e based o n Co - 60 ac ti v it y us in g t he m os t h igh ly ac ti va ted reac to r int e rn a ls, th e b a ffl e pl a tes.

NRC SPECIFIC CONSIDERATION Sc:

An estimate of the number of discrete radioactive particles that may remain at the Zion site after the survey is completed (i.e., discrete radioactive particles either missed or below the MDA).

ZIONSOLUTIONS RESPONSE:

See th e r es p o nse to Sp ec ifi c Co n s id e ra t io n 3c fo r th e d esc ripti o n of t he m e th o d to be u sed t o es timat e th e numb e r of DRP s that could hy p o th e ticall y re m a in. Th e res ult s w ill be provided t o th e NR C in t he TS D th a t d oc um e nt s th e s urvey res ult s.

NRC SPECIFIC CONSIDERATION Sd:

An estimate of the radiation dose from the particles that may remain at the Zion site after the survey is completed. In developing its survey plan, the licensee should consider, as a minimum,

the information provided in this RAJ, as it may apply to the Zion facility.

ZIONSOLUTIONS RESPONSE:

T h e DRP d ose assess m e nt m eth o d is d esc rib e d in th e res p o nse to Sp ec ifi c Co n si d e ra ti o n 3 b. T he res ul ts w ill be p rov id e d t o th e NR C in th e TS D that d oc um e nt s th e s urv ey re s ult s.

NRC RAI-lla:

~ustification that the licensee statement that the 2018 URS surveys confirmed that the concrete on the outside of containment meets the " free release " criteria given the reported remediation and detections of contamination recently provided to the NRC. This justification should address remediation that appears to have been performed on the containment building exterior concrete in 2018 and scan alarms and smear measurements that appear to be above the MDA in the 2018 URS survey results for the containment building exterior concrete. This justification should also include an evaluation of how the 2018 URS results compared to the 2016 URS results.

ZIONSOLUTIONS RESPONSE:

Th e sta tem ent th at "... t h e co n c re t e o n th e o uts id e of c o n ta inm e n t m eets th e ' free re lease' c ri te ri a... " is in refe re n ce to its st a tu s af te r re m e di a ti o n. T h e fact th at co nt amin ati o n was d e t ected and re mediat e d sh o uld no t b e inte rpret e d to m ea n th a t th e materi a l did n o t m eet th e free r e lease c rit e ri a befo r e it was re use d o r di sp ose d off-s ite.

P age 85 of 96 ZionSolutions, LLC ZS-2022 - 010 Attachment The s urve y data from the 20 18 URS that was provided in the enc los ure to the Fe bruar y 10, 202 1, re spo nses in c lud ed pre-remediation result s that indic ated that plant-derived radioactivity was detected as we ll as p os t-remediation dat a w hich s howed no detect a bl e radioactivity above b ackgro und. For each in s tanc e in which a sta tic a larm was recorded and /or w here s mear re s ult s we re above Lo, the area wa rerned iated or re m oved and s ub seq uentl y re ur veyed. In eac h occurrence, th e loose s urface co ntamin a ti on was wiped clean, or the eleva ted material was removed in it s e ntir ety, a nd the a rea was resurveyed to ve ri fy th e re was no lo nger a ny p lant derived radioactivit y above background. T he se res ults are co n sistent w ith the text included in the February 10, 202 1, RAI respo n se in which ZionSolutions s tate s that this concrete m ee ts th e " free relea se" cr iteria.

The 2018 URS, in compar iso n wit h the 20 16 URS, found more e levated areas above background. This was ex pect e d, as m ore D&D wo rk was cond u cted adjacent to the Conta inm ent Buildings ( in sta ll at ion of waste load o ut tents, creation of access h atches in the Contai nment s,

s ign ificant dem o liti o n of radioactive structures adjacent to the Containments). The le ve l of s urv ey was s ig nifi ca ntl y incr ease d for th e 20 18 U R S to acco unt for the changing conditio n s of the s ite.

NRC RAI-llb:

A description of the extent of contamination observed on the exterior containment building concrete after that area was put under isolation and control (i.e., 2016). This description should include:

summary of the areas identified as potentially above background from scan alarms or smear sample measurements in the 2018 URS survey, including the measured activity and the approximate location (e.g., elevation [less than 3 meters or above 3 meters], the proximity of the location to key features [such as equipment hatches, tent enclosures], and whether the area was located on the Zion Unit l or Unit 2;

summary of the area of the containment building exterior concrete remediated during or after the 2018 URS surveys;

post-remediation data for the Zion containment building concrete that has not already been provided and /or a description of where the post-remediation data is located if it has been provided (e.g., which pages of the "2 018 Unit I and Unit 2 Containment Exterior URS" attachment contain the post-remediation data).

ZIONSOLUTIONS RESPONSE:

The exterior s urface s of the U nit 1 and Unit 2 Containment Buildin gs we re put under isolation and co ntr o l measure s during the 20 16 URS. T h e iso la t ion an d contro l measure s remained in place until Janua ry and February of 2017 w he n the tent s were constructed. T h e iso lation and

Page 86 of 96 ZionSolutions, LLC ZS-2022-010 Attachment control mea sure s r e mained in place for all other area s of the Containment Buildin g exteriors outside of the tent enc losure. Becau se the isolation and contro l mea sures were n o longer in place within the tent s, the exterior s urface s of Containment w ithin the tents, as well as ot he r areas outside of th e tent, were s ubject to a m ore ex tensi ve URS in 2018.

All areas id e ntifi ed as potentially above background were e ith e r rem e diated by wip in g clean or removed in its enti rety as s h ov.rn in Table 29.

The fo ll ow in g table provides a s ummar y of the s tatic beta m eas urement s th at exceeded the alarm set-points durin g the 2018 URS for the exteriors of the Unit land Un it 2 Containment Bu il din gs.

The table al so identifies whether the area was located on Zion Unit l or Unit 2, the elevation, and the proximity of the loca tion to key features.

Tabl e 29-2018 URS Elevated B eta Static Measurement Summary Scan Scan Area Number Alarmed Alarm U nit Area Loc a tion of A la rm s Reading s Set - Point Remediation ID (c pm ) (c pm )

1 1 3-9 m hei ght 1 1750 477 dec ontamination by wiping

3-9 m height, near dec o nta mi nation by 1 3 conta inm ent access 2 32 15, 2494 787 hatch w iping

1 4 3-9 m height, near 3 540,6 50, 750 477 dec o ntamination by tent opening wiping

3-9 m hei ght, near decontamination by 1 8 containment access 2 2703, 1150 787 hatch wiping

1 13 0-3 m height, near 2 728, 777 507 dec o ntaminati o n by tent opening wip i ng

1 15 3-9 m h e ight, near 1 1050 723 dec ontam inati o n by tent opening wiping

1 16 3-9 m height, near 1 980 723 dec o ntamination by tent opening wiping

1 24 0-3 m height, near I 4616 763 dec ont amination by tent opening wiping

0-3 m height, near complete rem ova l 1 47 containment access 2 3400,2075 762 hat c h of scan area

Page 87 of96 ZionSolutions, LLC ZS-2022-010 Attachment

Scan Scan Area Number Alarmed Alarm Unit Area Location of Alarms Readings Set-Point Remediation ID (cpm) (cpm) 0-3 m hei g ht, near 1122, 2089, comp lete removal I 48 con ta inm ent acces 3 1947 of sca n area 762 hatch

I 58 0-3 m h e ight 2 648,939 494 decontamination by wiping

1 59 0 - 3 m height 1 810 543 dec ont amination by w ipin g

3-9 m height, near 564, 525, dec o ntamination by 2 1, 2 tent opening 6 580, 409, 394 466, 975 wiping

2 13 0-3 m height, near tent opening 2 486, 542 371 decontamination by w ipin g

2 15 3-9 m height, near tent opening 1 1990 392 complete removal of scan area

2 18 0-3 m h ei ght, near tent opening 2 798, 528 371 decontamination by w ipin g

0-3 m height, near decontamination b y 2 41 conta inm ent access 1 599 543 wipi ng hatch 0-3 m h eight, near decontamination by 2 42 co ntainment access l 577 543 w ipin g hatch 0-3 m height, near decontamination by 2 43 containment access 1 566 543 wip in g hatch 0-3 m height, near decontamination by 2 44 containment access 1 661 543 w ipin g hatch 0-3 m height, near decontamination by 2 45 containment access l 609 543 wipi n g hatch

The following table provides a li st of all the smea r s that were identified as above Lo.

Page 88 of9 6 ZionSolution s, LLC ZS-2 0 2 2-0 l 0 Attachment Table 30- 2018 URS E levated Smear Summar y Unit Smear ID Count Number Beta Activity (dpm) Beta Lo (cpm) 1 1 1 3 5.99 9.08 1 1 2 6.74 9.08 I 5 7 I 9.66 9. 08 1 57 2 0.89 9. 08 I 8 1 9.6 6 9.08 1 8 2 3.81 9.08 1 13 1 9. 66 9.08 1 13 2 12. 59 9.08 1 13 3 0.89 9.08 1 59A 1 21.36 9.08 1 59A 2 3.81 9.08 1 59 1 12.59 9.08 1 59 2 -4.96 9.08 1 52 1 9.65 8.9 1 52 2 3.97 8.9 1 23 1 12.48 8.9 1 23 2 29. 51 8.9 1 23 3 -1.71 8.9 1 24A 1 9.65 8.9 1 24A 2 -4.54 8.9 1 25 1 15.32 8.9 1 25 2 9.65 8.9 1 25 3 1.13 8.9 1 15 1 2 1 8.9 1 15 2 4 6.54 8.9 1 15 3 -4.54 8.9 1 ISA 1 18.16 8.9 1 15A 2 2 1 8.9 1 ISA 3 -4.54 8.9 1 1 1 21 8.9 1 1 2 3.97 8.9

Page 89 of96

ZionSolutions, LLC ZS-2022-010 Attachment Unit Smear ID Count Number Beta Activity (dpm) Beta Lo (cpm) 1 4 3 14.99 9.08 1 4 4 12.59 9.08 1 IA 1 44.3 2 7.65

1 lA 2 41.84 9.08 1 I A 3 74.01 9.08 2 34 1 9.65 8.9 2 34 2 9.65 8.9 2 34 3 6.81 8.9 2 35 1 9.65 8.9 2 35 2 -4.54 8.9 2 40 ] 12.48 8.9

2 40 2 12.49 8.9 2 41 1 35. 19 8.9 2 41 2 21.09 8.9 2 44 1 52.21 8.9 2 44 2 32.56 8.9 2 10 1 8.33 7.65 2 10 2 16.64 7.65 2 10 3 2.79 7.65 2 7 ] 519.8 1 8.99 2 7 2 559.93 8.99 2 7 3 15.36 8.99 2 2 1 17.71 8.99 2 2 2 9.63 8.99 2 15 ] 21 8.9 2 15 2 29.51 8.9 2 15 3 57.89 8.9 2 15 4 38.02 8.9 2 13 1 8.05 (alpha) 4.2 (alpha) 2 13 2 3.89 (alpha) 4.2 (alpha) 2 3 1 3.95 (alp h a) 3.93 (alpha)

Page 91 of 96 ZionSolutions, LLC ZS - 2022 - 0 l 0 Attachme nt

Unit Smear ID Count Number Beta Activity (dpm) Beta Lo (cpm) 2 3 2 -0.18 (alpha) 3.93 (alph a) 2 4 1 7.74 7.65 2 4 2 3.81 7.6 5 2 1 (A3) ] 119.07 7.65 2 l (A3 ) 2 121.84 7.65 2 I (A3) 3 52.04 7.65 2 1 (A3) 4 72.01 7.65 2 I (A3) 5 96.92 7.65 2 1 (A3) 6 94.16 7.65 2 2 (A24) 1 13.28 7.65 2 2 (A24) 2 2.2 7.65 2 2 (A9) 1 18.82 7.65 2 2 (A9) 2 16.6 4 7.6 5 2 2 (A9) 3 30.4 8 7.65 2 2 (A9) 4 24.94 7.65 2 2 (A9) 5 13.87 7.65 2 2 (A9) 6 32.66 7.65 2 1 (Al 7) I 4.97 7.65 2 1 (A17) 2 22.17 7.65 2 1 (Al 7 ) 3 5.56 7.65 2 1 (A 17) 4 13.87 7.65 2 I (A l 7 ) 5 36. 02 7.65 2 1 (A l 7) 6 8.33 7.65

Po st-remediation data for the s urvey performed on the U nit 1 exterior is included in the "2 018 Unit 1 and U ni t 2 Co ntainm ent Exterior URS" report on pages 124-128. Post-remediation dat a for g rid s 1, 2, 13, and 18 in the U nit 2 s urve y is in c lud ed in the report on page 202. A dditi o n al po st-remediati o n data for th e U nit 2 s urvey was not in cluded in the s ubmitted report and was inad ve rtentl y not digitall y arch ived b efore being sent to long-term records stor age. As such, the d ata is not readil y ava ilabl e. Zio nSolution s is co nfid ent that rem ed iation and re s urvey of th e rem a ining Unit 2 elevated sca n areas was performed satisfactor il y ba se d on the followi n g:

Multiple stag es of profe ssio nal review a nd approva l of the s urveys are required and were executed prior to the struct ure bei n g deemed ready for open air demoliti o n.

Page 92 of 96 ZionSolutions, LLC ZS - 2022 -01 0 Attachment

The manager responsible for the work ha s co nfirmed that this process was fo ll owe d und er his supervision.

T h e same review and approva l process was required for Unit 1, w hi ch is documented by the scan p ro vided pre v io usly.

To the extent there is any que stion regarding the level of co ntamination of the CCDD, a ll of survey unit s in whic h the contai nm e nt exterior CCDD was temporarily sto red, transported through, o r loaded into railcar s are included wit hin the s cope of the DRP Surve y Pla n a nd were surve y ed. The only except ions to this are those s urvey units t hat went thro u g h FSS a nd ORISE confirmation followi n g the removal of the CCDD.

NRC RAI-llc:

Justification that the process for the URS surveys and the determination that material met the

" free release criteria" is consistent with commitments in the L TP:

a description of the process used to determine which areas to remediate and how large of an area to remediate (i.e., once radioactivity was detected, how large of an area around the detection point was remediated and /or excluded from being part of the "free release "

concrete material);

an evaluation of whether the process for including or excluding concrete from being considered as " free release material" is consistent with the L TP conditions on URS.

ZIONSOLUTJONS RESPONSE:

Proces s Description. The process u se d to determine which areas to remed iate, that is, for the URS performed on the exte ri or s urfaces of the U nit 1 and Unit 2 Contai nm e nt Buildings and the determination that the material m et the free release criteria, is described in Section 5. 7.1.12 of th e Zio n LTP, wh ich sta tes :

The d ecommissioning approach for ZSRP ca ll s for th e beneficial reuse of co ncrete from building demolition as clean fi ll. CCDD is defined as uncontaminated broken co ncrete witho ut protruding metal bars, bricks, rock,

sto ne, reclaimed or other asp h a lt pavement o r soi l ge nerated from construction or demolition activities. On ly concrete debris that meets the definition of CCDD w ill be considered for use as clean hard fi ll a nd on ly whe n surve y s have demonstrated that the concrete is free of detectable residual radioact ivity.

If an elevated reading was observed, th e area was bo und ed and marked wit h paint. T h e paint ed area was remediated, and a ll remediated material wa s contro ll ed and disposed of as radioactive waste. T h e entire area th at was remediated was resca nn ed to ver ify that it was suitab le for free release. A ll areas w ith d etectable radioactivity above background were remediated an d

Page 93 of96 ZionSolution s, LLC ZS - 2022 -01 0 A tt ac hm e nt res urveye d t o ve ri fy s uit a bili ty fo r fr ee re lease and use as fill m a ter ia l (i.e., CC DD ). A d esc ripti o n of th e appro x im ate ar e a re m e di at e d for e ach e leva t e d m eas ur e ment was n ot al ways prov id e d in th e fie ld logs; as s u c h, exac t s izes fo r re m e di a ti o n a reas is unkn o wn. R ega rdl ess of how l a r ge a n a rea t o re m e di a te w as, th e e nti re are a was res urveye d fo ll ow in g rem e di ati o n.

T here are no in sta nces w h e re CC DD th a t was use d as fi ll m a t e ri a l or o th e r co n crete th a t was re lease d fro m t h e s ite ha d d e tec t a bl e pl a nt-r e lat e d ra di oact iv ity a bove b ac k gro und. A li st of th e areas th at were remed iated is prov ide d in Ta ble 29. A ll sca n a reas li sted in t h e tab le we re e it her d eco nta min a te d by w ipin g or co mplet e ly re m ove d. A descr ipti o n of th e app rox im a te a rea rem e di ate d fo r each e leva t e d meas ur e m e n t was not a lways p rov id ed in th e fi e ld logs; a s s uc h, exact s izes fo r re m e diati o n a reas is unkn own.

Con s is tenc y with LTP. For CC DD re mainin g o n-s it e as fi ll m ate ri a l, th e p rocess fo r s urvey in g a n d appl yi ng d ose is full y co n s ist e nt w ith th e L T P as ev id e n ce d by th e an swe r to t he prev io us qu es ti on. Thi s approach w a s app ro ved by th e NR C du r in g the L TP s ubmitta l and rev ie w pro cess (see t he res p on se t o RAT-4a a nd RA T-4d o n E nc los ure I to ZS - 2 017-0 0 84 (A D A M S Acc ess io n No. M L I 7215 A 095 ) dat e d Jul y 2 0, 2017 ).

NRC RAI-lld:

Justification that the URS surveys were performed adequately, including :

a description of the process used to analyze the smear sample results, including : the method for determining if radioactivity above background was found in the sample (i.e., whether

" Unc ", the MDA, or some other criteria was used and a description of what " Unc" represents if " Unc" was used as the basis), a description of the process for determining whether smear samples were recounted, a description of which data was used in the evaluation of whether radioactivity above background was present when a sample was counted multiple times, and a justification for excluding data from the evaluation if any data was excluded.

justification that concrete that had been located above 3 meters on the containment building exterior does not contain any residual contamination given the survey scan coverage of I 0%.

ZIONSOLUTIONS RESPONSE:

Process for analyzing smear sample results. T h e m eth o d for d e t e rminin g if radi oa cti v ity a bove backgro und was fo und in th e sampl e was t o d e te rmin e if th e ac ti v ity ex cee d s L o. " U nc "

represe nt s th e unc e rta in ty. T h e un ce rta in ty was n ot u se d as a b as is fo r d e te rminin g if acti v ity was ab ove ba c k g round.

Process for determining whether smear samples were recounted and which data was used.

S m ear sa mpl es we r e rec ount e d if e ith e r th e alpha o r b eta act iv ity exce ed e d L o. S m e ar s ampl es were reco unt e d to ve ri fy if th e act iv ity re m a in e d th e sa m e o r de c re a se d. A d ecre a se in a c ti v ity ove r a sh ort pe ri o d of tim e indi cat e d th e prese n ce o f rad o n o r NORM. T h e las t c o un t of a sm ea r P age 94 o f 96 ZionSolutions, LLC ZS -2022 -0 I 0 Attach m e nt samp le, if it was counted mul t ipl e tim es, was u se d for eva lu at ion. This a li g n s with standard indu stry practice when the presence of radon o r NORM is a factor.

Justification for excluding data. T h e o nl y data that were ex clud e d fro m eva lu atio n were those s uper se ded by further co unt s. Jn the se cases, the hi g her act iv ity of the or igi na l smear was innu e nced by the pre se nce of rado n or NORM. lt is a standar d indu s try practice to recount the s m ear afte r a ll owing time for decay a nd to discount the re sult s of th e or ig in a l ana lys is.

Justification for r ed uced survey scan coverage above 3 meter s. The pathway for contam in at io n below 3 m eters wo uld be co nta c t b y personne l o r eq uipm e nt o r by ai rborn e material within the tent enclosures. B eca u se it is n ot normal for p erso nnel o r equipme nt to come into co nt act with bui lding s ur faces above 3 meter s, it was determined that there was a low potentia l for those s urfac es to co ntain co ntami na ti o n above ba ckgro und. Because th e re was a low p roba bilit y of finding s urface co ntaminati o n a b ove backgro und, th e s urfa ces a b ove 3 m eters we re de s ig n ated as C lass 2, and per pro ce dure l 0 % scan coverage was pre sc ribed. In exception to this, the exterior s urfac es above 3 m eters w ithin th e waste tent were des ig nat ed as C lass 1 beca u se of the greater pot e nti a l for a irb o rn e co nta min atio n. As s uc h, I 00 % of the s urfaces within th e was te tent e nclo s ure we re s urveye d.

NRC RAI-lle:

Evaluation of whether the containment building exterior concrete contamination (and /or the processes responsible for the contamination) could be a source of particles observed by the NRC,

its contractor ORISE, and the licensee on the Zion site. This evaluation sho uld include:

an evaluation of the root cause for radioactivity being detected in 2018 but not 2016 (i.e., was the initial survey inadequ ate, or was there a breakdown in isolation and control measures?) ;

a description of the containment structure concrete, if any, from an area with detectable radioactivity above background that was included in the " free release material " (i.e., CCDD) that was disposed of on-site or that was moved through areas of the site post FSS;

an evaluation of whether the factors that led to the detection of contamination on the Zion containment building concrete could have led to similar problems elsewhere on the site and,

if so, a description of corrective actions that were taken or will be taken by the licensee to address the problem.

ZlONSOLUTIONS RESPONSE:

Root cause for time of d etection. Z ionSolutions doe s not beli eve that the radioactivity b e in g detected in 20 18 but n ot 20 16 is the re s ult of in adequate initia l surveys, a breakd own in iso la tion a nd co ntrol me asures, or any o th er pro cess fai lu re. Rath er, Z ionSolutions believe s it is a re s ult of the seq uencin g ofre mediati o n. Severa l areas ofre medi atio n in 2018 occ urred n ear the Unit 1 an d Unit 2 Co ntainment Buildin g e quipm e nt h a tch openin gs w hich re sided w ithin the was te loadout Page 95 of96 ZionSolutions, LLC ZS -2022-0 10 Attachment tents, w her e a irb orne co nt ami n atio n was a com m o n occurre nce. The loadout tents we re n ot present durin g the 20 16 U R S. It is n ot un expecte d that a reas s urveyed ( co rrect ly) as clean during th e 2016 UR S might have been found to conta in co ntamin at ion in 2018. R ega rdl ess of the time at whic h activity was detected, the surfa ce was de co ntami nate d if contamination was d etected.

Description of concrete includ ed in CCDD. o portion s of either containment structure with detectable act ivity were used as CCDD or released from the s ite without prior decontamination.

The contamination identified on the exterior of Unit l and Unit 2 containment in 2018 was low level loose -surface contamination due to airborne radioactiv ity. All areas with detectab le radioact ivity above background were remediated and resurveyed to verify s uit abi li ty fo r free release a nd u se as fill m ate ri a l (i.e., CCDD). There are no instances where CCDD that was u sed as fi ll material or ot h er concrete that was re lease d from the s ite h ad detectable plant-related radioactivity above background.

Evaluation of factors that led to contamination of concrete structures. P otentia l factors that led to the detection of contamination on the U nit 1 a nd U nit 2 Containme nt Building exte ri ors were was t e h and lin g act ivities wit hin the waste loa d out enc los ur e or cross-co ntaminatio n from personnel or equipme nt. Waste loadout enclos ur es were not used or associated with ot her s it e buildings, a nd a ll ot her s ite buildings h ad been demolished prior to the demolition of the Unit 1 a nd U nit 2 Co ntainm e nt Buildin gs. As s uc h, Z ionSo lutions doe s not believe that these factors co uld have led to s imilar problems e lsew here o n the site. Thus, no correct ive actions have b een taken or planned.

ZionSolutions believes that the foregoing respo n se a l so addresses the RC comment on p. 35 of the RAI letter, which states, "The me asurement of radioactivity above background in the 2018 URS survey appears to b e inconsistent with the text in in the February 202 1 RAI response (i.e.,

that the 2018 survey confi rm ed previous measurements)."

Page 96 of9 6

ML22089A098

Text

Subject:

Attachment:

Navigation menu

Search