ML20127L979
| ML20127L979 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 08/25/1972 |
| From: | Marx D NORTHERN STATES POWER CO. |
| To: | Muller D US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 9211250322 | |
| Download: ML20127L979 (10) | |
Text
none twe NORTHERN STATES POWER COMPANY August 25, 1972
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Docket No. 50-263 Mr D R Muller b
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Assistant Director for Environmental Projeets i -i. \\ -
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D Directorate for Licensing U S Atomic Energy Con =ission D#
.N Washington, DC 20545 s\\
Dear Mr Maller:
MONTICELLO INCLEAR GENERATING PLANT E-5979 Errata Sheets and Page Substitutions For Responses to Coments Draft Environmental Statement Enclosed are 50 copies of errata sheets and page substitutions to the NSP Responses to Coments, Draft Environmental Statement for the Monticello Nuclear Generating Plant (dated August 9,1972).
It is suggested that the attached errata pages be inserted to replace the pages now in the text in your possession and those which have twen distributed by your office.
Yours very truly, E C Ward, Director Engineering Vice Presidential Staff By Daniel J Rarx, PhD Environmental Biologist Oc:
G Charnoff D E Nelson Enclosure 9211250322 720825
'g C<?3 PDR ADOCK 05000263 P
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t August 21, 1972 NORTHERN STATES POER CCl@ANY Monticello Nuclear Generating Plant Responses to Federal, State and local agency comments on the AEC Draft Environmental Statement.
ERRATA SHEET A!!D P/ "E SURSTITUTIO!!S Attached are errata sheets for direct substitution into the text of the above de cument.
It is suggested tha1 each of the< attached pages be inserted to replace the pager now in the text in your possession.
Old pages should be discarded.
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Errata for responses to Federal, State and local agency com ent or. the /JC Draft Environmental Statement, Monticello lhtelear Generating Flant.
Pare No.
Line No.
Errats 14 12 Change " station" to " stations" l
36 23 Change "comunity" to " population" 33 18 Change "epecie" to " species"
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38 20 Replace sentences beginning i
"The fichec present" i
to read The fishes present would not inhabit the warmest waters located at the outfall of the canal but would most i
likely reside in the waters a few degrees above ambient temperature. These fishes vould not experience a full 27oF drop in temperature because tho' physical nature l
of the circulating water system is such that under normal shutdown, the change takes place gradually and permits the fish to l
seek preferred temperatures."
4 i
PF.:P.FORMANCE EVALUATION OF BWR l
15 25 Change "peovided" to "provided" 17 27 Change " instruction to " introduction" 19 7
Change "A" to "As" i
19 1.8 Add a ec=ma after " plant"; delete comma after " drums" 4
20 20 Change "frummed" to " drummed"
t (8) Coment:
... discrimination be made between the benthic organisms in the near shore and offshore habitats in more detail, indicating which organisms are found in each area and their percent contribution to the total populations.
Response
The data are available to qualitatively distinguish these two habitat types. Differences in sampling techniques preclude complete
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quantitative comparison.
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, of c senthic organism sampling stations have been maintained since 1969 9f g,4 as part of the p eoperational ecological studies program.
These stations 5.%
are located across the river at various transects ine'-41ng the main rine channel and relatively close to each shore. It iuld be recognized that this part of the river is fast moving with many rapied. The shorr St each side is scoured by the river cnd the shore location varies vi.
the level of the river.
The Annual Report v9-1971) on the Monticello Environmental Monitoring Program describe the abundance and distribution of benthic organisme in the river.
(9) coment On pge II-17, it is stated that populetion estimates for came fish in table II-4 were adjusted to com-pensate for differences in sampling programs. We suggest that a description be made of the method used to adjust the population estimates.
Response
This method is described in NSP's Environmental Monitoring Program Annual Report 1969, Ecological Study pp 102 et seq.
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't (3I) Gment :
l The draft statement discusses the effects of the intake structure and velocity on fish and concludes f
that some impingement or entrainment cf small fish entering the intake canal vill probably-occur. These effects may become most significant during the vinter vhen varm water is recirculated to the intake canal to prevent ice formation. -Purther evidence is i.e-sented showing that survival of entrained larval fich will be low. Based on the discussions in the j
statement, it vould appear necessary to redertign the intake structure to reduce fis.,."trainment.
Year-round closed-cycle operation vould significantly i
reduce this problem.
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j The cuggested redesirn of the intake structure carries with it an im-plication that the existing intake structure si ald be replaced. This broad conclusion is tenuous in light c f the information upon which it is i
i based and at best the sugr.estion is clearly premature.
The theoretical discussion of impingement problems considers neither i
i the actual biological conumnity in the river nor the operating experience.
Preliminary entrainment studies at Monticello have included the in-1 tentional introduction into the circulating water system of a population'of I
Fathead minncve.
Recapture of a portdon of this experimental population was accomplished by seining and netting at the outfall of the discharge canal. Of particular importance is the result that only the species artifically introduced into the system were recovered.
A tentative con-alusion is possibles naturally occurring' species are generally not subject t.o entrainment into the circulating water system. This conclusion is sup-ported by a consideration of the nature of the minnows in,the river.
Be-cause of the high velocity of this natural river environment, these small cpecies are naturally entrained by the river.. They must remain near I
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i ctudied.
The occurrence of these lov flow conditions is infrequent.
Closed cyde operation is anticipated at extremely low flows, furthermore, the mixed riwr temperature is always limited by the 1GCA dischar6,e permit.
A redistic assessment of the potential for vinter fish kill resulting fron cold chock must 61ve reco6nition to several considerations. Foremost is t.he long experience of USP in the opration of power plants in Minnesota.
This experience has shown that fish kill from cold shock does not constitute a potential impact of any real significance.
There are no quantitative andyses, however, NSP has experienced only one known cold shock fish kill and it did not-involve game fishes.
The discharge canal at. Monticello is relatively short.
It does not provide the physical accommodation wherein larEe numbers of fishes could congregate. This physical limitation would limit the extent of-the potential impant. The fishes in the Mississippi River at Monticello are species whom themal tolerance is significantly different from those fishes that
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have been the subject of reported fish kills.- For example, the Menhaden in 8 warm water fish that cannot survive in the cold vinter waters of Minnesota. This-species is not present at Morticello.
The comment suggests that fishes would. be subjected to an instantaneous 27oF temperature drop.
The fishes present would not inhabit the varmest location at the outfall of the canal but would moet likely. reside in tb -vaters a few d+ grees above.amb*.ent temperature.
These fishes y
would not experience.a full 270F drop in temperature because the.
physical nature of the circulating water system is such that under normal shutdown the change takes place gradually and permit the fish to seek preferred;. temperatures.
(33) Comment:
Since the pre-operational studies did not identify spawning areas-in the vicinity of the plant, a.
study should be made-to identify andl quantify such areas. :Since valleye are one of.the most numerous
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B.
System Modifications e
To improve the operability of the solid radwaste system, equipment or system modifications were made or operating techniques were implemented in the start-up and early plant operating phase.
The following_ discusses some of these modifications and the reason (s) forithe-change.
1.
During start-up operations large masses of the anion floc agent which is a gelatinous material was found in the bottom of the collector tanks and was suspected of causing filtration problems with'the radwaste filters.
1 Subsequent laboratory testing - of the filterability of the floc agents showed that a. solution of the anion agent (Dow Purifloc A-22) ~ would not flow through a vacuum milipore filter even when diluted to approximately 0.5 ppm.
The cation agent (Dow Purifloc C-31)?gave no filter- '[
ing problems. However, because the-cation agent yields only a_small improvement in the-settling _ properties of-the neutrally charged Solka-floc sludges (finely ground cellulose material) and because of the< natural agglo-meration properties of the positively and negatively charged Powdex sludges _ (finely _ ground ion Lexchange resins) the need for the cation agent was examined.
All floc agents have since been discontinued in the' solid rad-waste system.
2.
Flow meters (rotameters)- provided on the-centrifuge inlet 1 lines to measure the feed rate have plugged several times i
with small pieces of paper, cigarette butts and.' teflon tape which are entering the' system via the floor drainage system.
Coarse mesh Y-strainers have been added upstream of the flow meters to allow removal of-the foreign material.
3.
When centrifuging solka-floc sludge the concentration of fines in the centrifuge effluent is greater than when centrifuging the Powdex sludge.
Additionally 1the decan-
_I tate from a solka-floc slurry has a greater _ concentration of suspended fines than does_the decantate from a Powdex slurry.
Field _ testing has indicated thatithe concentra-tion.of solka-floc fines.in the decantate and the centri-I fuge effluent can be reduced if-the solka-floc sludge is admixed with Powdex sludge.
-To accomplish this:the fuel pool and radwaste filter _ sludges in the waste sludge-4 tank are now transferred to the Condensate Phase-Separa-i tors and mixed with the Powdex sludges prior to the -sedi-mentation and decantation steps.
This flexibility had-i already been designed into the system.
4.
A concrete mixing _ station o. the screw conveyor type-was added between the hopper and the. drum filling' station on, one of-the hoppers.. This concrete mixing step was added y
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i so.that Reactor Water Clean-up Sludge would meet;the burial site requirement that any-resin with radioactivity
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greater th'an 1 Ci/ft3 must be fixed in concrete.
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As can be seen in the above table Solka-floc fines do not settle as readily as does Powdex, Run No. 1 with 13 ppm compared to Run No. 3 with 81 ppm.
However, the settling characteristics of Solka-floc can be improved by adding a Powdex backwash to the Solka-floc backwash and mixing and allowing the slurry to settle.
The 81 ppm in the decantate from the Solka-floc slurry can be reduced to 31 ppm when mixed with Powdex (Run No.
2).-
Also the separation effi-ciency of Solka-floc does not appear to be as high as the separation efficiency for Powdex in the centrifugation step as indicated by the effluent' concentrations for a Powdex feed and a mixed feed of Powdex and Solka-floc, 295 ppm and 400 ppm,respectively.
The concentration of suspended solids in the centrifuge e
effluent can be significantly reduced by sedimentation step for any feed material.
The table shows reductions from 295 to 16 ppm and 400 ppm to 30 ppm.
This was the justi-fication for returning the centrifuge effluent to the phase separator to obtain the additional settling step.
Run No.
8 indicates that the centrifuge effluent concentration can be improved even further if mixed with a Powdex backwash prior to the settling step.
Run No. 9 was made to deter-mine if the addition of a floc agent to a Powdex and~Solka-floc backwash would reduce the concentration of fines in the decantate.
As shown, the 30 npm was reduced to 20 ppm; how-ever, it was believed that the reduction was not worth the introducdon of floc agents to the system.
1 The. reduction from 81 ppm for a Solka-floc backwash decan-tate to 31 ppm when mixed with P'owdex prompted the modifi-cation to the system operation to transfer the Waste Sludge Tank (primarily solka-floc) to the Condensate Phase Separa-tors (Powdex) and mixing the two slurries and allowing them to settle.
Table V shows a comparison between the design values and the actual values currently experienced in the system for the following parameters.
Backwash Frequency Total Backwash Volume Backwash Water Processed Centrifuge Operating Time Sludge-Mass Estimated Sludge Volume Daily Sludge Volume Radiation-Level Activity Level This table is presented to show the relationships between the design and actual system parameters and t'o indicate, to some degree, the performance capability of the system.
As can be seen on the table the backwash frequency of the Condensate Demineralizers increased by a factor of 3 for -.
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the actual over the design because of a 1/3 reduction in run length currently being experienced.
This increase in backwash frequency is reflected by a corresponding tripling i
of the backwash water to be, processed through the radwaste filters, a tripling of the centrifuge operating time and a tripling of the sludge quantities ultimately to be drummed.
1 As discussed previously the use of the Floor Drain Filter has been discontinued and is noted on the table.
The use of the fuel pool filters to periodically process liquid radwaste has not been indicated on the table which shows the backwash frequencies for the-filters in their respective services.
The water used to backwash the various filters is ultimately processed through the radwaste filter.
The individual batch backwash volumes have been calculated on a daily and totaled to yelid the total daily contribution of liquid radwaste from the backwash operations.
This backwash source is approximately 50% of the total monthly liquid volume processed through the radwaste filter.
The individual centrifuge operating times were also calcu-lated on a daily basis and then summed to give a total daily centrifuge operating time.
The actual daily operating time for the centrifuge has decreased even though the centrifuge operating time for the condensate demineralizer system has increased three-fold.
This reduction is due primarily to the use of the Condensate Phase Separators for the fuel pool.and radwaste filter sludges which achieves a ten-fold increase in sludge concentration; with a corresponding re-duction in centrifuge operating time.
Daily sludge volumes were calculated from the various sources based on a dry bulk density of 18 lbs/ft3 This yielded 19 drums / month for the design value and 45 drums / month for the actual with both numbers based on 5.6 ft3 of, sludge per drum.
The low level drums are currently being shipped on I
unshielded vehicles, 60
.90 drums per shipment.
As can be seen the radiation levels for the actual drums is two I
orders of magnitude less than the level expected in the design phase.
The low activity level in the sludges is due, in part, to the shortened condensate _demineralizer runs, to lower activation product concentrations in the reactor water ( an order of magnitude less than the design value) and perhaps to a higher reactor water-to-condensate separa-tion f actor for the activation products.
'(10-3 was used for the design value).
As stated above the plant is oper-ating with a fairly low offgas rate-of '/10,000 pCi/sec, after 30-min decay, which indicates low. fuel-leakage rates and therefore most of the activity contribution is from activa ~ tion products and _ not fission products.
In the initial' operation of the plant, drums were going into y
storage on the remote conveyors with removable contamination of.<100 dpm/100 cm2 This contamination level was typical of the external contamination for-both the drums which were _
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y not solidified and for drums which were solidified with
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concrete.
These low levels were parcially due to the low activity levels in the sludge for that early period of plant operation.
However, since the early phases the plant has been operating with virtually no liquid releases and the Chemical Wastes and Laundry Drain Wastes have been mixed with dewatered Condensate Demineralizer Sludges as a. method-of disposal.
at 260% moisture and are mixed with the liquid wastes toThe 270% moisture before being drummed for shipment.
This sludge is somewhat more fluid than the normal. centrifuge cake dis-charge and consequently a small amount of splashing does occur in_the drumming operation.
Current contamination levels are typically 700 dpm/100 cm2 for the low level drums and 3000 dpm/100 cm2 for the high level drums.
Drums above the allowable 2200 dpm/100 cm2 are washed down by operators.
A remote drum wash down station is being considered for addition to the plant.
6 Dry solid wastes consisting mostly of rags, paper and other contcminated articles are compacted and drummed in 55 gal.
drums.
I An average of 5 drums per month of dry wastes ' are generated in the operation of the plant.
IV.
Summary and Conclusions The Monticello Radwaste System, as designed and with the oper-ating modifications described herein can-meet the recently pro-posed Appendix I release limits for liquid effluents.
These limits can be met by recycling the Clean and Dirty Radwaste Streams for plant reuse and routinely discharging the chemical and laundry. wastes.
Further studies and evaluations should be undertaken to determine the advisability and cost of achieving-essentially a zero release liquid radwaste system by further processing of the Miscellaneous wastes.
The radwaste system, to date, has not limited plant availability and it is believed that the system will not limit the plant operation in the foreseeable future.
The water quality-of the wastes recycled within the plant has been within specified design limits and should continue as such.
Decontamination factors should increase with higher fuel leakage rates and correspond-ingly higher enfluent activity levels.
However, because of the total recycle operating mode and the continuous recirculation operation (the wastes pass through the process many times rather than a once-through ap of particular concern.proach), decontamination factors are not The system has performed with relatively trouble free operation with the exception of the element plug-ging problem and high external contamination on the 55 gal. drums.
Thus it appears from the operating experience to date_that the Monticello Nuclear Station has provided for a highly effective radioactive waste control program through-the use-of a relatively simple radwaste system. 3
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