ML19312C943

Supplements AO-270/75-19 Re Unplanned Release of Radioactive Water Through Turbine Bldg Sump.Caused by Inadequate Coolant Storage Sys Test Procedure Which Did Not Ensure Reconnection of Line to Isolation Valve

ML19312C943
Person / Time
Site:	Oconee
Issue date:	12/29/1975
From:	Parker W DUKE POWER CO.
To:	Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19312C932	List: ML19312C934 ML19312C939 ML19312C943
References
NUDOCS 8001140599
Download: ML19312C943 (15)

Text

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U1F IC I? POW 101f COM PAN Y ~

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Te e s see E*s*ne.oe %.eee. Tattse=ecast' A*t a ?os 37 3- e 0 0 3 Decenber 29, 1975 -

Hr. Norman C. Moseley .

U. S. Nuclear Regulatory Commisnion Suite 818 ~

230 Peachtree Street,' Northwest Atlanta, Georgia 30303 Re: Oconee Unit 2

! Docket No. 50-269 j AO-270/75-19

• Dear Mr. Moseley; fy 7 etter of October 17, 1975 transmitted Abnortnal Occurrence Report 1,\O-270/75-19 concerning an nump.

unplanned release of radioactive liquids 7

through the Turbine Building Thin 1ctter provides supplemental iinfu.m.. tion section of that report.

seintive to the "ven2gnatson of Apparent Cause of Occurrence" The line which allowed the discharge to the Turbine Building sump was originally intended to connect the secondary side of the steam generator to the allowing condensate storane tank via the component drain pump, thereby for quick drainane of the stetsm generator during initial testing by pumpinn with the cornponent drain pump. An investigation into construction records shows that th.t component ' risin systers was turned over from the Construction Department with a note t. hat the lineto the Steam Production Department in Pehruary 1972 from the component drain pump to the condensate otorage tank was cut to allow for a nyntem flush. This was not formally identified, however, as an exception in the turnover documentation.

, Steam Production Department Preoperational Test Procedure TP/2/H/230/12

" Coolant of the Storage Syntem Finish", required that the line he cut downstream isolation was verified on March valve in the vicinity'of the Turbine Building sump. This 21, 1973, and the f3ush was completed on March 22, 1973.

There was no requirement in the procedure to as:.ure that the line was restored to its original intended configuration. Had this been accomplished, two isolation valven would have separated the contaminnted quench tank drain system from the condensate storage. system and one Icaki,ng valve would not have resulted in releasic of radioactive liquid. -

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_ L Mr. Norrun C. Moceley ~~ '

1 December 29, 1975 .

l Page 2 I l Therefore, it in considered that this incident was primarily caused by a procedural inadequacy in the Coo 3 ant Storage System preoperational test procedure.

Ve truly yours,  ! , -

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William O. Parker, Jr. *

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o ember 29, 1970 9-1 9.0 C0! TROL OF RADIOACTIVE EFFLUElqS The staff evaluation of the applicant's radiation protection measures is contained on pages 55-58 of the Oconee Unit 1 SER.

The earlier evaluation of radioactive waste management pple- was su mented as discussed below.

s The applicant was requested to provide additional informatio n to show that the unit vent radiation monitor system will have the required sensitivity for measuring the an' t icipated levels either

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for a continuous or instantaneous release andneto discuss plate out.

The applicant was also requested to verify that the charcoal to be used in the rauiation monitors for iodine is impregnated to assure the collection of both elemental and non-

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elemental forms of iodine and to provide information as toe th frequency at which the charcoal will be changed and tested .

In addition, the Technical Specifications were revised to 1

meet the intent of " low as practicabid" with regard to full utiliza-tion of waste processing equipment and were revised to meet the intent of Regulatory Guide 1.21, Measuring and Reporting of Effluents rom f

Nuclear Power Plants and to specify the reporting of anned all pland

. unplanned releases of radioactivity.

On the basis of its review of the information submitted

. , the staff concluded that .

the proposed radwaste systecs for reduction of radioactive material in effluents and radiation monitoring

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systems satisfy the requirements of 10 CFR Part 50.34a of the Commission's Rules and Regulations for keeping levels of radio-

. ective material in effluents to unrestricted areas as low as practicable.

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Effluent Treatment Systems _

The ; te# treatment systems were designed to provide for controlled handling aan disposal of radioactive liquid, gaseous and solid wastes.

! The applicant's design objective for the radwaste systems was to release amounts which are within the limits' set forth in 10 CFR Part 20.

In addition, the applicant agreed to maintain and use existing plant equipment to achieve the lowest practical radioactive releases to 6

+ the ncironment in ::::rd:ne with the requirements ef 10 CFP. Part 50.

The liquid waste treatment system was sized to accommodate the waste ,

produced during simultaneous operation of Units 1, 2 and 3 and is com-mon to all three units. Table 9-1 gives component data for the liquid waste treatment systems. Units 1 and 2 share a common waste gas --

treatment system. Unit 3 has,a separate waste gas treatment system which is interconnected to the system for Unit 1 and 2; however, these systems normally are operated independently. ,

The waste gas treatment system is capable of containing fission product gases stripped from the reactor coolant to permit decay of

" short-lived radioactivity before release to the environment.

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The solid waste system packages waste in accordance with the regulations set forth in 10 CFR Parts'70-71 and conforms to the Department of Transportation shipping regulations.

9.1.1 Liquid Vante l

. System Description The/ liquid radioactive waste system, cor: mon to Units 1, 2 and t

3 consists of collection tanks, piping, pumps, evaporators, deminer-alizers, process equipment and instrumentation necessary to collect, i

process, monitor, store and dispose of potentially radioactive liquid I wastes. The system is divided into two main parts; (1) the rea-tor coolant treatment system (RCTS) which includes the chemical and i

-vu luine control s'ystem (cvud) and (2) the liquid waste treatment system 1 l

l (LVIS). Treatment of the waste is dependent on the source, activity and composition of the particular liquid waste and on the intended disposal procedure. Cross connections between the subsystems provide flexibility for processing by alternate methods. More than half of the estimated maximum total radioactivity is collected in the LWTS and the rest from the RCIS.

Treated wastes are handled on a batch basis as require d to permit optimum control and release of radioactive' waste. Prior to release of any treated . liquid wastes, sac:ples are analyzed to determine the type and amount of radioactivity in a batch. Based on the results of an analysis, these wastes either are released

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s 9-4 under controlled conditions to the tailrace of the Keowee Hydroelectric Station or are retained for additional. decay or further processing.

Radiation monitoring equipment automatically terminates liquid waste discharges if radiation lev.els are above a predetermined icvel in the discharge line.

Reactor Coolant Treatment System (RCTS)

The reactor coolant treatment system, which includes the CV,CS, l i

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! processes the coolant letdown stream and other chemically clean l l l sources such as equipment leakages from valve, flange and pump seal l leakoffs within the reactor coolant system. Each unit has separate coolant bleed holdup tanks but shares a common coolant treatment .

I system. tue nuts ptocesses une izquid vf hishest activity in thrae dif ferent ways. Ordinarily part of the liquid is circulated through demineralizers to remove corrosion and fission products. After purification, part of the liquid is bled from the system and fed to the reactor coolant bleed evaporator (10 gpm) in order to remove' the boric acid from the system. As neutron-absorbing fission products buildup in the fuel and as th'e fuel is depleted, it is necessary to continuously reduce the boron concentration. Reduction in boron concentration is . accomplished primarily in the reactor coolant biced

, evaporator. Most of the recovered ~ boric acid is stored for reuse t

in the system. The condensate from the evaporator is collected in

. the condensate test tanis from which it can be discharged to the 1, .-

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9-5 tailrace or used as makeup wate r for the reactor. If necessary, the condensate can be processed th or recycled through the evaporator urther to frough a mixed b .

In the later stages of a core life time, reduce its activity.

is accomplished by the deborating de further i removal of baron m neralizers.

The staff estimated that approxim t a ely 330,000 gallons from each Unit will be processed annually by th e reactor 5

porator resulting in an estimated rele coolant bleed eva-radioactivity (excluding tritium) ase of 0.6 curies per unit of l .

This annual release was based on the assumpti estimate of the a t i

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' coolant bleed will be released each yea on that all of the reac I

and decap for a r af ter processie Holdup 30-day parind was assumad pri

.ar ta relesse.

applicant calculated a concentration l  !

. discharge from one unit into unrestrictedevel of 0.026 MP i areas.

both processed and unprocessed bl Holdup volumes for eed are adequate.

cluded that The staff con-the reactor coolant treatment system is capable of providing effluents which are consider

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as low as practicable in accordance with 10 CFR Part 50 .

Liquid Waste Treatment System (LL*TS) .

The liquid waste treatment system collects and treats all chemically impure wastes that can not b .

e released untreated. ,

expected that yore than half the esti It is will be collectad in three different tymated maximum total r

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9-6 (miscellaneous waste, high-activity waste and low-activity waste).

Principal sources are floor and equipment drains,, some leakof fs, and wastes from chemical laboratory drains, decontamination area drains, laundry wastes and demineralizer regenerants.

Liquid wastes' expected to have a low-Icvel of radioactivity are i

Auxiliary building floor f collected in the low-activity waste tank. - ,

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drains, laundry and shower wastes are expected to make up the major

! Af ter sampling and analysis, these wastes fraction of these wastes.

either are discharged directly to the tailrace of the Keowce Hydroelectric Station or are transferred to the miscellaneous waste (10 gpm) . .

, holdup tanks and ard processed through the waste evaporator '

I In the staf f evaluation, it was assumed that all low-level waste is processed through the waste evaporator before release to the environment. r is processed The staf f estimated that 50,000 gallons per year per unit e i

annually. .

Liquid wastes expected to have an intermediate level of radioactivity ,

Principal sources are collected in the high-activity waste tank. .

are.the decontamination wastes, demineralizer regenetants, vaste gas 6 f'

i Based on the activity level .

system and spent fuel systems drains. .

of these wastes they are either transferred to the low-activity waste

• tank for release to the tailrace or are transferred to the waste evapo-a rator for processing. Normal processing is through the waste evaporator.

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9-7 The staf f estimated that approximately 30,000 gallons per year from

, Unit 2 will be handled by this system, and a similar amount from Unit 3.

Liquid waste expected to have a high-level of radioactivity is collected in the miscellaneous waste holdup tank. Principal sources are the recycled wastes from the condensate test tanks, reactor e.

, building sump / sample sinks and leakoffs frem the reactor vessel and

, coolant biced tanks. This, vaste either is transferred to the

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low-activity waste tank for discharge or is processed'through the waste evaporator. The staff assumed that all this waste is processed through the evaporator and estimated that approximately 100,000 gallons per year, per unit is handled by this system.

Condensate from the waste evaporator is collected in the condensate test tanks, sampled and analyzed, and either reused in the plant or released. The bottoce fro = the evaporator which contain the concentrated impurities is transferred to the solid waste dru= ming facility and packaged as solid waste.

Oconee, Units 2 & 3, like Unit 1, have 'once through steam genera-tors, hence there is no secondary blowdown. Instead, reliance is placed on " full flow" Powdex polishing demineralizers upstream of the feedwater train. These demineralizers are capable of' treating 70% of the feedwater flow at full power. ,'

The applicant analyzed the effect of a leak from the feedwater  !

i system into the turbine room sump. This leakage normally is '

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9-8 discharged into Lake Keowee via the cooling condenser discharge. If

, significant activity occur,s in this liquid, provisions are made .

for routing it into the radioactive vaste treatment system for treat-ment prior to release or reuse.

The staff estimated that the untreated

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annual releases from this source are not expected to be a contributing source of oc't ivity.

f l Estimated releases of radioactivity from the LWTS by the applicant we::e determined on the basis of each unit operating with defective fuel and assumed that all liquid collected was reactor coolant con- .

taining the design fission product activity. It further was assumed that collection took place over a period of 60 days at a rate. of 435 gallons / day and included an additional holdup of 30 days for decay prior to discharge. The resulting station effluent concentration averaged over 60 days was estimated by the applicant to be 0.16 of the MPC for unrestricted areas.

The staff estimated an annual relea,se of 1.1 curies of radioactivity (excluding tritium) from each unit. This estimate assumed that all waste collected in the LWTS are pcocessed through the weste evaporator prior to discharge and considered each unit operating with 0.25% of '

the, operating power equilibrium fission product source term. Based .

on present operating experience at other operating plants, the staff estimated 1000 curies per year of tritium is released from each unit.

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9-9 The staff concluded that the LWTS has sufficient capacity to permit flexibility in station operation and the means of providing ef fluents considered "as low as practicable".

Radioact've i liquid waste released from the station is from either the low-activity waste tank or the condensate test tank. In order to aphieve the highest dilution ratio, the' applicant committed where possible to coordinate releases with the operation of the Keowee Hydroelectric Station'.

Assuming that the waste is , diluted by the annual average flow of 1100 ci,s, then the a scrage activity of the discharge could be 3 x 10 pCi/cc.

Estimates of doses to individua,ls from liquid effluerits at Clemson and Pendleton, where drinking water is withdrawn f rom the Ke'owee River, were 0.64 mrem to the thyroid and

0. 50 .:.r. tu th.

huis 'uudy . These dvse estimates inorcatec that releases of radioactive effluents from normal operation of the station are conducted well within the limits of'10 CFR Part 20 and are considered as low as practicable in accordance with 10 CFR Part 50.

The staff concluded that the design criteria of che liquid redwaste sys tem were acceptable. ,

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C0; TROL OF RADIOACTIVE EFFLUENTS Liquid and gaseous vaste handling facilities are designed 4 to process waste fluids generated by the plant  ;

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so that discharge of liquid and gaseous eff1uents to the environment will be minimized .

Liquid waste is processed both by, direct removal of radioactiv e i material with ion exchange resins and by evaporative separatio n.

j Using these methods the volume of radioactive waste will be greatly reduced and the purified liquid streams will either be

reused or discharged. 1 Small quantitias of radioactive liquid i

h l waste will be released routinely to the Keowee hydro

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tail race where the waste will be diluted and discharged to the Keowce River. ,

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tha: The limits on routine radwaste releases froms the three unit requirearethat planned for' operation at the Oconee Nuclear Station will L

the combined releases from the three units when ,'

adled together be within the limits specified in 10 CFR Part 20.

. The specific limits for both liquid and gaseous effluents are j g!

included in the Technical Specifications ,

Under normal operating, .'

conditions, however, i't is expected that

• liquid waste releases E will contain radioactivity in concentrations that are less th .g an 1% of the 10 CFR Part 20 limits and that ..

I, the concentrations in. j .f I gaseous 20 limits. releases will be only a few percent of the 10 CFR Part n-

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' Liquid wastes are collected according to expected radio

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activity content: -

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routed to the waste holdup tanks, intermediata activity wastes - .

are routed to the high activity waste tanks, and low activity wastes are routed to the low activity waste tanks  : .

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Low activity wastes can also be present in the condensate test tanks (which, '

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9, have been evaluated as such since they are a source c of dire t release of radioactivity to the plant radioactive waste discharge li ,' ,k i1 1

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In addition to bvidup, other means are available to reduce  ;

the radioactivity in the liquid wastes before release. A waste 6

evaporator and a coolant biced evaporator are provided. These have the ability to remove radioactivity by evaporation, returning

- the distillate to the coolant bleed holdup tanks for reuse as reactor coolant r.akeup, and routing the concentrate, under appropriate conditions, to the solid waste drumming station for i packaging as solid waste. Demineralizers also are provided in i

the coolant, treatment system, and these can be used to remove f l

f radioactivity f rom liquid wastes prior to release. o As a j

' Liquid waste releases are made on a batch basis.

result of frequent operation of the onsite hydro-station, almost all liquid waste releases are expected to be mixed in a dilution l flow substantially greater than the minimum 30 cubic feet per second dilution flow that would be available if the hydro station s.

is not operating. In all cases,' the radioactivity content of the

' waste is measured prior to release and monitored during release.

Oconee Station has been designed and built to minimize the {

possibility of an accidental release of liquid radioactive waste. [

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The plant design includes the location of all liquid radioactive waste treatment system components below grade in Class I (seismic) structures. Therefore, in order for liquid radioactive wastes -

-to be accidentally discharged, they must be inadvertently pumped f to the environment. This p,u= ping capability is controlled from the Unit 1 control room. Further, the radiation monitors on f 4

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the liquid waste discharge line will terminate the discharge of l radioactive liquids if the concentration in the discharge line l when mixed with the minimum Keowee Hydro Plant flow (30 cubic h

feet per second) would exceed 10 CFR Part 20 limits. The .

Technical Specifications require that liquid wastes 'be discharged ,

e only if (1) concentrations within the limits of 10 CFR Part 20 .

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1 can be schieved considering no more than the minimum u c 30 c bi fcer per second dilution flow, and (2) j i

monitors are operable. the effluent line radiation duplicate sampling and analyses of the contents of th i e low level waste tanks and the condensate test tank prior to iii n t ating any liquid discharge from these tanks.

We have, however, evaluated ha consequences of a postulated accidental release of liqu wat,te resulting from a multiplicity of operator er rors.

We assumed 3 I that the contents of the low level waste tank s were inadvertently

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pumped to the Keowce hydre plant tailrace. ,

This would result in radioactivity concentrations in the tailrace several ti 4 mes 10 CFR d Part 20 limits, assuming a minimum dilution flow j of 30 cubic . . ,

feet per second in the tailrace.

However, even if a person t were to derive 1 day's supply of drinking water di rectly from the tailrace (the nearest drinking water supply is the Clemson

.'k ee intake 13.7 miles downstream) the resulting d:s Q:

e to the person

- ' would be a few percent of his allowable acc jd,-

umulated ycarly limit. '[ N;,

Because of additional dilution and the approximat ely 2.5 days .: p required for water from the tailrace to reach the Clemso ,,,,

n intake O-(allowing substantial decay) the resulting dose st ut would be further reduced. .that location i vi 3.,

{, which is owned by the Duke Power Company, is monitoIn i.

red for radio-k

} activity and, if necessary, its use can be terminated to 1-1/2 days (storage capacity) to permit a f f

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3 h u. urther reduction in radioactivity entering the water supply . .hb ,

P- Caseous radioactive wastes, apart from steam gener ator or

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heat exchanger leakage, will be collected principall y from the

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. various ' liquid storage tanks assoc.inted with theorreact plant.

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All gaseous radioactive vaste releases will ben mo it f4 '

hi ^ discharge., ored during l t 9,} '

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in addition, any release from the vaste gas collecti on sys, tem or prior to release. the rea'etor building will be analyzed for acti v ty i -

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also is regularly monitored for activity to detect radioactivity f releases that could occur as a result of steam generator leakage.

Similarly, low pressure cooling water systems used to cool com- Y I

ponents containing reactor coolant are monitored regularly to '[

detect radioactive in-leakage. Tne consequences of a rupture of '

a waste gas decay tank are noted in Section 11.0 of this j evaluation.  !

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No solid plant wastes will be permanently stored at the Oconee  ;-

l 1 t-i site and all solid wastes collected and temporarily kept at ,r, 1

the site must be shipped offsite for ultimate disposal at an

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AEC licensed disposal site. .

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We have concluded that.the radioactive waste system and

. the procedures for the control of radioactivity releases from Oconee Unit No. 1 arc acceptable. l I

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