ML20236L324

Forwards Response to NRC Request for Addl Info Re Shipping of Facility Components for Disposal as Radwaste.Attachments 2 Through 6,provided to Assist in Answering Questions 3 & 5. Rev 2 to Rept 9801-7025 Encl

ML20236L324
Person / Time
Site:	Saxton File:GPU Nuclear icon.png
Issue date:	07/07/1998
From:	Kuehn G GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20236L328	List: ML20236L324 ML20236L350
References
1920-98-20343, NUDOCS 9807100314
Download: ML20236L324 (8)

Text

{{#Wiki_filter:_ _- ,- l l GPU Nucleer,Inc. ( Route 441 South NUCLEAR '**'**c******* Middletown, PA 17057-0480 July 07,1998 1920-98-20343 i ' U; S. Nuclear Regulatory Commission Attn: Document Control Desk 1 Washington, D.C. 20555 Gentlemen:

Subject:

Saxton Nuclear Experimental Corporation Facility Operating License No. DPR-4 Docket No. 50-146 Response to the NRC Request for Additional Information Regarding the Shipping of Facility Components for Disposal as Radioactive Waste. l Enclosed is the SNEC Facility response to the subject request for additional information dated May 11,1998 It is being submitted to support the documents referenced in the question section headers. Attachments 2 through 6, are being provided to assist in answering questions 3 & S. s Sincerely, 1 / L G. . Kuehn i J v, v a 1 Vice President SNEC -WGH j Attachments: / l

1. Response to the Request for Additional Information

2. Westinghouse Electric Corporation, Atomic Power Department Drawing 6463830 "Saxton i

Reactor Plant Reactor General Assembly", dated August 31,1961.

3. Westinghouse Electric Corporation, Atomic Power Department Drawing 821D181 "Saxton M

Reactor Plant Lower Core Guide Block Assembly", dated October 30,1960. bg - 4; Saxton Reactor Plant Lower Core Guide Block - 3 photos.

5. '"Saxton Pressure Vessel and Internals Final Characterization", Report WMG 9801-7025,

- dated April 1998. 6. Table 4-19 of the SNEC Site Characterization Report (SCR) NM pf caiqs cc: NRC Project Manager, NRR-Alexander Adams g m (;Gs ggy~gy0Y i Thamac F Dragoun -PDR ADOCK 05000140 c

- LY- - - PDR f

[, u - 1920-98-20343 Page 1 of 4 REQUEST FOR ADDITIONAL INFORMATION SAXTON NUCLEAR EXPERIMENTAL FACILITY DOCKET NO. 50-146 1. Can SNEC confirm that the lower core guide blocks (guide blocks) in the reactor vessel are the only Greater Than Class C (GTCC) waste? Explain. (See questions 3 and 4 below.) Response: GPU Nuclear has performed extensive radiological characterization of the SNEC Facility. The results of the characterization indicate that to the best of our knowledge, the lower core guide blocks are the only Greater Than Class C (GTCC) Waste. The assessment that the lower core guide blocks are GTCC is based on a conservative activation analysis rather than actual measurements due to the difficulty in obtaining an actual sample of these blocks. With regard to the remainder of the facility, radiological characterization has been carried out using actual samples and measurements while applying conservative assumptions to curie and waste classification modeling. To the best of our knowledge, other wastes are not GTCC. The SNEC reactor vessel (RV) internals isotopic distribution is a product of activation analysis calculations of a tyne typically performed for reactor vessels that undergo neutron flux as a result of the nuclear fission process. TLG Services Inc. (TLG), the contractor = who performed the activation analysis of the SNEC RV has extensive experience in performing activation analysis calculations of this type in that it routinely performs activation analyses in support ofits decommissioning cost studies. Accordingly, TLG has . performed hundreds of simplified analyses, encompassing 85% of the nuclear power plants in the U.S. Further, TLG has performed detailed neutron activation analyses, similar to that provided for the SNEC Facility, for several other clients in support of decommissioning plans submitted to the NRC (Cintichem, Big Rock Point, Trojan, Yankee Rowe (core shroud), Humbolt Bay-3, San Onofre-1, Shoreham, Rancho Seco, Pathfinder, Shippingport and Dresden-1 nuclear plants). ' TLG also provided a detailed activation analysis in suppon of the decommissioning cost estimate it prepared for the Fort Calhoun Station. TLG's calculational results are reasonable when compared with measured exposure rates - from inside and near the RV. - The response to Question 5 provides information on the waste classification of other SNEC Facility components. ' All evaluated components are within Class C limits and SNEC Management is not currently aware of any other components or systems that would have a 10 CFR 61 waste classification of GTCC. When taken as a whole, the SNEC Facility containment vessel piping systems have been found to be within Class C limits. A significant reduction in the currently estimated curie

1920-98-20343 Page 2 of 4 content of piping is expected due to a reduction of background radiation values following the removal of the large components. Removed sections of piping will be taken to lower background areas for re-measurement and/or temporary storage prior to shipment for disposal. System piping re-evaluations will continue to refme the curie content values of j components and system piping as decommissioning progresses. 2. Section 3 - The neutron activation analyses assumed various fuel configurations to reflect the use of uranium oxide and mixed oxide fuels. Are these simplifying assumptions conservative in terms of overestimating the concentrations of nuclides important for waste classification? (See Note 1) Response: Yes, these assumptions are conservative in terms of overestimating the concentrations of nuclides important for waste classification. According to SNEC facility operating records and core performance reports, UO fuel 2 was the only fuel type used on the core periphery. The core model (fuel configuration) developed for the analysis assumed that UO was the only fuel used in the core. This 2 i simplified assumption is appropriate for the radial activation model since fuel on the core boundary has the most significant impact upon the neutron spectrum beyond the radial core boundary. This simplified assumption is slightly conservative for the axial activation model (in terms of overestimating the concentrations of nuclides important for waste classification), since mixed oxide fuel produces a " harder" neutron spectrum. This harder spectrum results in less activation products in structural materials within the vicinity of the core, such as the lower core guide blocks. l Irrespective of the modeling technique and underlying assumptions, it is important to remember that the analytical results were bench-marked against actual in-vessel measurements. As part of the analysis, calculated dose rates based on the results of the l reactor vessel radioactive inventory analysis were compared against measured exposure rates. The approach and results of this comparison were included in GPU Nuclear's response to Question 30 of the NRC's June 30,1996 Request for Additional Information l Regarding the SNEC Facility Decommissioning Plan and Environmental Report. In the response letter (C301-96-2038 dated July 18,1996), GPU INuclear referenced the TLG Activation Analysis Report as Reference 14 and provided it as Attachment 2. I 1 l 3. Section 7.3.1 - This report stated that the guide blocks are GTCC waste if classified individually, but because the guide blocks are permanently bolted to the lower core plate (plate), the guide blocks and the plate can be blended, and that the blend of guide blocks and the plate is within the Class C waste limits. Provide a clear picture or diagram that illustrates the bolted connection between the lower core guide blocks and the lower core plate. (See Note 1) l Response: Please find enclosed two drawings (Attachments 2 and 3) and three photos (Attachment 4) taken from a video inspection of the reactor vessel interior which clearly 4 1

\\ g 1920-98-20343 Page 3 of 4 show the lower core guide blocks, the bolting arrangement and their location in the reactor vessel. The lower core guide blocks are securely and permanently attached to the l lower core support plate with stainless steel fasteners that are crimped in-place to prevent l loosening. In addition to being permanently bolted to the lower core support plate, several features of the disposal plan will be implemented prior to disposal to enhance this attachment. The interior of the reactor vessel will be filled with low-density cellular concrete (LDCC). This material will serve to further fix all reactor vessel internal components in place, including the lower core guide blocks The five-inch thick reactor vessel will then be placed inside a two-inch thick carbon steel shipping and disposal canister. The inner space between the reactor vessel and canister will also be filled with LDCC. This arrangement will result in at least seven inches of carbon steel and considerable LDCC surrounding the l l l lower core guide blocks. The waste classification of the SNEC facility reactor vesselis explained in more detail in l,"SAXTON REACTOR PRESSURE VESSEL AND INTERNALS FINAL CHARACTERIZATION", Report WMG 9801-7025. This report was prepared by WMG, Inc. in support of the SNEC Large Component Removal Project and provides a concise description of the reactor vessel waste classification. 4. Section 4.2.10 - Justify blending the pipe sections that are individually GTCC with other piping systems. Guidance for averaging concentrations in homogeneous waste types is presented in Section 3.1 of the " Branch Technical Position on Concentration Averaging and Encapsulation", January 17,1995. (See Note 2) Response: There are several options available for disposing of the SNEC facility piping systems. The "best" option is considered to be that in which the piping, components and stmetural steel are sent to a vendor for metals reclamation. Vendor negotiations are presently underway, with the expectation that a selected vendor will be contracted to dispose of most of the SNEC Facility waste metals inventory. An alternate approach has sections of the SNEC Facility piping system being sent directly I to a burial facility with the remainder sent to a processor. These selected piping sections will be packaged pursuant to the guidance provided in the " Branch Technical Position on Concentration Averaging and Encapsulation" published January 17,1995. This approach allows " volumetric or weight averaged nuclide concentrations of the mixture, provided { that the concentrations of the individual waste type contributors to the mixture are within l a factor of 10 of the average concentration of the resulting mixture" (other than primary gamma emitters), and within 1.5 for the primary gamma emitters. 1 l 1

.. r ,k. 1920-98-20343 q Attachment i Page 4 of 4 5 Table 4 identify the waste class of the items listed as "To Be Determined"(TBD) if these items have been evaluated and classed (See Note 2). Response: Attachment 6 is an update to Table 4-19 in the SNEC Site Characterization Report (SCR). It updates values for all "TBD" items. Estimates are conservative and await additional sample results or low background radiation measurements for possible j refinement. l 4 Note ! Question based on the "Saxton Facility Reactor Vessel, Internals, Ex-Vessel Lead, Structural Steel and Reactor Compartment Concrete Shield Wall Radionuclides Inventory" dated December 1995. Note 2 Question based on the 'SNEC Site Characterization Report" dated 1996.

4 g. g g g g g - i. )

,nt

. k, dt }, _,^ .e. ,t "- i, 'y<- yv. acVb. "_ ~ 4. a- ' _3 4wb~- '

3 y'

N

,. _, ' ~ -[' _s - 'b' b-a' g 5 ~ s r

f..

n A--

~*

o u -. n1~ *- ys 5 4, a:[dM s. 3x g ~ a

p

' - ;. mn p pr5 .s . y9 K 2 p.'

• y,.

H .'c C . ;3

y -

~ 4 p-n.I';q x^. w_ J.n ^ r. 9' . w }- QhwN+ y O 'w &d3 S ,r k L 2 4 w,. , a 5.- g B y s , _M3 _d' 3-T [ )E..'( g=wY N E e, l._ 1 ~ .,fn. sK_ 4 f f ._~. D ,s K,' 0.h . m ~ j=. U _fp j] ~^<,;f D. vf', I c g 4 J cS. .Cu_ . a ;7,s..%e .e eN ,_ ;l v c. o.. g G ? j we *,t:h_nup;n. ~.e, p ~ E +c., -, -. g': ~' a ~ W= %,' ', ?.y ' b ~l: g4,'d R n. 6 ;.? 9 _k*% g .n _.y' 5 O ~ 1* V %'^ *%c.ic ..y9.e .Y d ' y%_ s_

m

) C i ~ L - s ' -. ' 9 _ 7+ , ' N y g*, ~ ;g. -._j:. R 7..' 4, ,A%,: 't E \\w;.,.. J s W

• Qa't

^.- h 4 5 .p O [ . n. b' _ O' -{'- a,_, m w I L

w

~ a k; y, S_ 3 r Y -._"pgi [ w ;gy gm k f m BOLT + w d + d- "d Il

E% e u f e M

1. g g

a. g;

s..

i+W ' e. s 'r. L.- 2 d u . c s ^ ~ A h

• w

.A ( ' i.. W amW=.-, s m k . N '%.i ,w L.. 5 d7' W . j Y. t y .m. -.. f' e>,.' gw; ? y$:,.1 mi._ g ^- m ' <w.f 4 Qg. ~ d r 6[y ( ? h w1 .o i g# .Y'

2.,

u. .' e$e O' K e g. m m N a e f{"

g' w C

~. 4gyx' . j* d awMu3r. ^'{ l, t pg; s_p' ' O a m g:n w 1 - s$ 9g.: ..b L s s. q,; C e' j fg B

c<

h w %'n E lge ya}. y' w M. .=k, f s.f= a D f jf T'j 's' ~ I / .f - U m 7 ,r i., m L G E i R m 4 '- 1 O p C 'r a R R $a ,, 4a c.- E v Wh ,5.- g O L ~ m dm B LT 4w- 'm S% i'e V r b k I p ,l-

w y i a, e. m = w s w y m s. m_ ,;,.3j. }]ia' l i3 .4g. ~ ~ 'g

• +..?. _*g

. r l:L.. . ;%e-e

y p

-., ;g& ( i -.,.~;. a f",k. i f ? - e !,m L - v.,,

~

3.~d s y m 4 ~ j .D l' 4.,_ ,~-_ y. m[;h;;9 '. w. s y ..c 3 r s, ,n v ,M e. - e x w-w .t y Q-f K ~ gg,'. g -C h ) c h ~$[1 f. i e ~ O ~ c. w .s = N

-. o _

3 m,. ^

[~' L ~ B y- - -.. ' h. Qrm0 f g' ^ c S i .E' y q U. E gs,. ;, 4 g#.T :. .w .w; ? - q L ,5 D sg

7 c

-, yh+. 2g 7..s i -. _w c.: ~ .5. ? : : Q,._d,. j O w.. U I g

. G;Lf.

[D s.yn g' a m- 'h G ~l p ' ?n _ 4_ g7,'^ E

6 v_

?, g 1)

n

+ D; R s-[g%y!;v i ' g m f. w; O am- ~.. C i

/

. 3 . X,. r. . + R m [ 6;' e 'y 2 [- ' <=

e

[ w.T.A $ T' fI - ~f MD' - d = a W E y s.MyvN.fs W n 4 e y' /.it .s W s g - 4 O m L 6 r e c 3 3 e. e e.t s e '= gpg4nb 4 " " s 'h po w a BO T "s =, =. + e. w r w w k e a.* i l -}}