Text

Proposed Tech Spec 4.7.6 Re Min Allowed Flow Through Cravs Filter Unit
	ML20077Q505
Person / Time
Site:	Catawba
Issue date:	08/12/1991
From:	; DUKE POWER CO.
To:	;
Shared Package
ML20077Q496	List: ML20077Q487; ML20077Q505;
References
	NUDOCS 9108210250
	Download: ML20077Q505 (11)
	v • d • e

.

t, I

}

\\

i 1

I l

}

Attachment I l

Marked Up Technical Specifications h

r

'L l

t i

i L

I t

l L

9108210250 910812 PDR ADOCK 05000413 P

PDR r

I e

-,, -.. -,., - - - - -. ~,...... - -.,,... - -.. - -

...... -....e

[\\j o [ha nc es to O'is page.

kLANTSYSTEMS 3/4.7.6 CONTROL ROOM AREA VENTILATION SYSTEM LIMITING CONDITION FOR OPERATION 3.7.6 Two independent Control Room Area Ventilation Systems shall be OPERABLE.

APPLICABILITY:

ALL MODES I

ACTION:

(Units 1 and 2) i MODES 1, 2, 3 and 4:

With one Control Room Area Ventilation System inoperable, restore the inoperable system to OPERABLE status within 7 days or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .-

MODES 5 and 6:

a.

With one Control Room Area Ventilatian System inoperable, restore the inoperable system to OPERABLE status within 7 days or initiate and maintain operation of the remaining OPERABLE Control Room Area Ventilation System.

b.

With both Control Room Area Ventilation Systems inoperable, or with the OPERABLE Control Room Area Ventilation System, required to be operating by ACTION a., not capable of being powered by an OPERABLE emergency power source, suspend all operations involving CORE ALTERATIONS or positive reactivity changes.

c.

The provisions of Specification 3.0.4 are not applicable.

~

-SURVEILLANCE REQUIREMENTS 4.' 7. 6 Each Control Room Area Ventilation System shall be demonstrated OPERABLE:

a.

At least once per 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months by verifying that the control room-air temperature is less than or equal to 90'F; b.

At least once per 31 days on-a STAGGERED TEST-BASIS by initiating, from the control room, flow through the HEPA filters and activated carbon adsorbers and verifying that the system operates for at least 10 continuous hours with the heaters operating; CATAWBA - UNITS 1 & 2 3/4 7-14 Amendment No. 78 (Unit 1)

Amendment No. 72 (Unit 2)

PLANT SYSTEMS SURVEILLANCE REQUIREMENTS (Continued) c.

At least once per 18 months or (1) after any structural maintenance on the HEPA filter or activated carbon adsorber housings, or (2) following painting, fire, or chemical release in any ventilation zone communicating with the system by:

1)

Verifying tha,t the cleanup system satisfies the in place penetration and bypass leakage testing acceptance criteria of less than 0.05% and uses the test procedure guidance in Regulatory Position C.S.a. C.S.c, and C.S.

of ulator Guide 1.52 Revisions 2 -ftamtv11T7BNui the stem f

rate is -0000 -cfe 10%4 beAween %4coe5;m and %oco dm')

2)

Verifying, within 31 da b

analysis of a representative activated carbon sample obtained in accordance with Regulatory Position C.6.b of Regulatury Guide 1.52, Revision 2, March 1978, meets the laboratory testing criteria of Regulatory Position C.6.a of Regulatory Guide 1.5 Revision 2, Mar od' ra ess tnan 0.175%; a d be%cen I.,, Goo cTm ma.vimu,m an \\ % coo cJ n, c

3)

Verifying a syste M te'ef d Y m

10 M y hum operation when tested in accordance with XNSI N510-1980.

d.

After every 1440 hours0.0167 days 0.4 hours 0.00238 weeks 5.4792e-4 months of activated carbon adsorber operation, by f

verifying, within 31 days af ter removal, that a laboratory analysis **

of a representative activated carbon sample obtained in accordance with Regulatory Position C.6.b of Regulatory Guide 1.52, Revision 2, March 1978, meets the laboratory testing criteria of Regulatory Posi-tion C.6.a of Regulatory Guide 1.52, Revision 2, March 1978, for a methyl iodide penetration of less than 0.175%;

e.

At least once per 18 months by:

I 1)

Verifying that the pressure drop across the combined HEPA filters, activated carbon adsorber banks, and m sture separators is opera urthe s a

less than 8 inches Water Ga ebe4 wcen b t 0ceb mo dmu' ""Cj flow rate ef-5000 c4m 10%

4,0 co c k m min,i mu m) ohs +ty*v ntate _.nn-Sm 2)

Verifying that on High R diatio -

High test signal, an alarm ceived in the control room; 3)

Verifying that the system maintains the control room at a posi-tive pressure of greater than or equal to 1/8 inch Water Gauge 1

relative to adjscent areas at less than or equal to pressuriza-tion flow of 4000 cfm to the control room during system operation; 4)

Verifying that the heaters dissipate 25 1 2.5 kW, and

The requirement for reducing refrigerant concentration to 0.01 ppm may be satisfied by operating the system for 10 hours1.157407e-4 days 0.00278 hours 1.653439e-5 weeks 3.805e-6 months with heaters on and operating.

- Activated carbon adsorber samples are tested at 30 degree C.

CATAWBA - UNITS 1 & 2 3/4 7-15 Amendment No. 85 (Unit 1)

Amendment No. 79 (Unit 2)

4 PLANT SYSTEMS SURVEILLANCE REQUIREMENTS (Continued) 5)

Verifying that on a High Chlorine / Toxic Gas test signal, the system automatically isolates the affected intake from outside air with recirculating flow through the HEPA filters and acti-vated carbon adsorbers banks within 10 seconds (plus air travel time between the detectors and the isolation dampers).

f.

After each complete or partial replacement of a HEPA filter bank, by verifying that the cleanup system satisfies the in place penetration and bypass leakage testing acceptance criteria of less than 0.05%

in accordance with ANSI N510-198 JOme-00P peseros @ wqil

~697he19sGDtN,JJ# rate ef-6000-c,a; i 10% k m a0 M m u m,j and oper be3 ua ec b,(coo eXm tv4xi m and 4 coo e g.

Aft snact omp ute,.nraarliabre ac ent of an activa _ted adsorber bank, by verifying that the cleanup system'!Ia'tisfies the in place penetration and bypass leakage testing acceptance criteria of less than 0.05% in accordance with ANSI N510-1980 fo.r a l

halogenatedhydrocarbonrefrigerg;i10%.est gas whil __ operating the system at a ptug0 % a bdwee r, lo (r00 Chy N.O.y.irn u m und 3

Llf 000c.S m min h n u m.

,A

.s^

i I

l T

f i

CATAWBA - UNITS 1 & 2 3/4 7-16 Amendment No.78 (Unit 1)

Amendment No.72 (Unit 2) i

i l

5 I

6 i-t f

t i

I i

I Attachment II f

Justification for Proposed Changes-and l

Ilo Significant Hazards Analysis 1

l l

?

r h

t I

f i

I t

N i

?

~!

l

{

I I

r I

i I

l

CATAWBA NUCLEAR STATION TECHNICAL SPECIFICATION CHANGE REQUEST BACKROUND The Control Room Area Ventilation System (VC) is designed to control temperature within the control room and control room areas (battery rooms, switchgear rooms, cable rooms, electrical penetration rooms, Motor Control Center (McC) rooms, and HVAC equipment roomF). The VC System is also de34.md to pressurize the control room.

Pressurizing the contr. e,m reduces the radiation into entry of dust, dirt, smoke, hazardous gase' the control room from adjacent

-r.U

=and

..ures that all air entering the control room has been filtered.

This design will ensure that the maximum radiation dose received by control room personnel is within acceptable limits.

The design bases functions described above are maintained by providing the VC system with two 100% redundant trains of equipment.

Only one of these trains is required to operate to satisfy the design bases requirements and, normally, only one train of equipment operates.

However, in the event of a blackout or LOCA, the pressurizing filter train and control room air handling unit of the non-selected train (the train that was not operating prior to the event) will automatically start.

This occurs in order to maintain continuous control room pressurization should the selected train fail.

After station personnel verify that both trains of the VC system are operating correctly, the system can be reset. When the system is reset, the non-selected train shuts down.

During a review of the Control Room Area Ventu ation System it was discovered that the failure of a control room return air damper (1CR-D-9 or 2CR-D-9) would adversely impact the ability of the system to pressurize the control room.

If the non-operating train return air damper f ailed to go to its f ail-safe position (full closed), the ability of the selected train to pressurize the control room would be compromised.

This damper failure provides an air flow path from the control room, through damper CR-D-3, to the outside air intake cross over duct, to the suction side of the selected pressurization filter train and fan.

This air flow path would impact the amount of outside air available for pressurization. The possible failure of this dampr is not a problem during normal operation

because, (1) normal operating procedures verify the damper position when ventilation trains are swapped, and (2) high radiation is not present during normal operations.

Therefore, there would be no adverse impact on control room personnel during the period of time between the f ailure of the damper and discovery that the damper had failed.

For the above reasons, this possible failure is only a

concern post-LOCA when pressurization of the control room is needed to ensure that the doses to control room personnel do not exceed GDC 19 limits.

~

l i

k 2 of 5 In order to ensure that the dose to the operators is not significantly affected in the event of a

LOCA, station i

operating Procedures have been revised to verify damper position af ter resetting the system.

If the damper on the non-selected train fails open when the system is reset, this train will be placed in operation, and the other train shut down.

This places all dampers in their fail-safe position (assuming only one single failure), and reduces the concern about the other train taking suction through the failed damper.

l l

Two different options were considered for permanently addressing this concern.

Both options considered have the effect of reducing required operator action post-LOCA, eliminating the adverse impact on control room pressurization

' due to a f ailure of either control room return air damper (lCR-D-9 or 2CR-D-9), and ensuring that the accident dose to control room personnel is maintained significantly below the GDC 19 limit of 30 rem.

Although some dose increase is associated with either option, this dose increase is significantly less than the potential dose increase associated with the failure of a control room air return damper (lCR-D-9 or 2CR-D-9).

The options were:

Option A: Install new low leakage, ASME N509 Leakage Class II, counter balanced backdraf t dampers in the outside air i

intake ducts on the suction side of the pressurizing filter train as shown on the attached diagram.

Option B: Block off the recirculation air flow duct that connects the control room return rir duct to the i

suction side of the pressurizing filter train as shown on the attached diagram.

Option A was rejected for several reasons.

This option would require the cutting of pressure tested welded construction ductwork to install flanges for mounting the new demper.

It also adds additional devices to the system that have a failure potential.

For example, failure of a backdraft damper to open i

when required would render its train of the Control Room Area i'

Ventilation System inoperable.

Also, this option is costly to implement and would increase maintenance concerns after implementation.

Option B

was chosen because it nas several advantages.

l Blocking the recirculation line removes the flow path which i

would exist in the event of the failure of the Control Room return air damper without adding another component which has a failure potential.

Option B also has the added advantage of eliminating the need for several compensatory actions necessary

_r to protect the carbon adsorber in the filter train while painting and welding are being done in the control room.

These i

3 of 5 compensatory actions would no longer be needed since air from the control room would no longer be circulated through the recirculation loop.

This option is relatively easy to accomplish, and is less costly than Option A.

CHANGES TO TECHNICAL SPECIFICATIONS Surveillance Requirement 4.7.6.c.1, 4.7.6.c.3, 4.7.6.e.1, 4.7.6.f, and 4.7.6.g, are changed to indicate the system flow rate is a maximum of 6,600 cfm and a minimum of 4,000 cfm, TECHNICAL JUSTIFICATION Duke Power Company has determined that blocking the recirculating air duct is an acceptable and safe method of resolving the control room return air damper concern.

This modification will have a min taal affect on the design bases dose calculations. The Technical Specifications will be revised to change the minimum air flow through the filter unit from 5,400 cfm to 4,000 cfm.

The maximum filter flow will remain unchanged.

The proposed amendment revises the minimum filter unit air flow limit from 5,400 cfm to 4,000 cfm.

The reason for revising this lower limit is that the proposed modification blocks the recirculation air duct which reduces the amount of air coming through the filter unit.

Thus a new minimum filter unit flow will be needed.

The new lower limit will be based on the minimum required air flow to adequately cool the pressurizing filter train fan motor.

The revised lower flow limit does not adversely af fect any filter train components (i. e. pre-filter, HEPA filters, carbon adsorber, etc.).

The filter unit maximum air flow limit will be unchanged since it is based on carbon adsorber residence time.

The present upper limit of 6,600 cfm (6,000 cfm plus 10%)

provides a minimum 0.25 second per 2 inch carbon bed depth residence time as required by ASME-N509 and Reg Guide 1.52.

Therefore, there is no need to revise the upper flow limit.

One of the design bases of the VC system is to ensure. that the dose to control room personnel is within acceptable limits.

An analysis based on Standard Review Plan (SRP) 6.4,

" Control Room Habitability System," has been done. The SRP outlines the ventilation system layout and functional design considerations that may be applied to the design basis accident (DBA) evaluation of the control room operator dose.

Eliminating the recirculation loop does not affect the calculated control room operator whole body and skin doses, since those doses are

a 4 of 5 dominated by the noble gas isotopes.

However, the calculated control room operator thyroid dose from the iodine isotopes is affected by the proposed VC System modification.

There are several control room ventilation-filtration system layouts discussed in SRP 6.4 which can be used in reducing the iodine isotope concentration within the control room atmosphere.

Iodine reduction for a particular VC System configuration is expressed in terms of the iodine protection factor (IPF) which is evaluated by considering an equilibrium balance between lodine sources and losses within the control room.

The IPF for the current VC System design is calculated to be.approximately 114 using SRP 6.4 methodology which corresponds to a DBA control room operator thyroid dose of 5.3 rem.

Removing the recirculation pathway results in an IPF of about 72 which yields a

calculated thyroid dose of approximately 8.4 rem.

This value is still significantly below the GDC 19 thyroid dose equivalent limit of 30 rem.

Therefore, the health end safety of the control room operatola will not be compromised by the implementation of Option B

or the corresponding VC Technical Specification revisions.

NO SIGNIFICANT HAZARDS ANALYSIS 10 CFR 50.92 states that a proposed amendment involves no significant hazards consideration if operation in accordance l

with the proposed amendment would not:

1)

Involve a significant increase in the probability or consequences of an accident previously evaluated; or 2)

Create 'the possibility of a new or different kind of accident.from any accident previously evaluated; or 3)

Involve a significant reduction in the margin of safety.

This proposed TS amendment will not increase the probability or consequences of an accident which has been previously evaluated.

The probability of an accident will not be increased because the Control Room Area Ventilation System does l

not initiate an accident.

This system is used to mitigate the l

consequences of an accident by ensuring that operator doses are within GDC 19 limits.

Lowering the minimum allowed flow for

+

the system to 4,000 cfm will allow the recirculation d t to be blocked off.

This flow represents the minimum flow required for the operation of the fan motor.

This modification will eliminate the concern about the possib'e f ailure of the control room return air damper impacting the ability of the VC system to pressurize the control room.

Blocking of f the recirculation duct eliminates the possible flow path between the two trains that would exist in the event the return air damper failed

+

5 of 5 open.

This modification will cause an increase in the calculated operator thyroid doses (5.3 rem to 8.4 rem), howeser the calculated thyroid dose is well below the GDC 19 thyroid dose equivalent limit of 30 rem.

The upper flow limit of 6,600 rem'ains unchanged because this limit is based on carbon residence time in the filter bed and not mechanical limitations of the system.

For the above reasons, this change will not significantly increase the probability or consequences of an accident previously evaluated.

This proposed revision will not create the possibility of a new or different accident from any previously evaluated.

The Control Room Area Ventilation System is not an accident initiator, it is used to mitigate the consequences of an accident on control room personnel.

Since this system does not have the potential to initiate an accident, no new or dif ferent accidents from any previously evaluated are created.

(

This proposed change does not involve a significant reduction in-the margin of safety.

Reducing the minimum required system flow will allow a modification to the system which will block off the recirculation flow, and eliminate a possible flowpath l

between the two ventilation trains.

This modification eliminates the possibility of the failure of a control room return air damper impacting the ability of the VC system to pressurize the control room because of the flowpath between the trains.

Eliminating the recirculation pathway results in an increase in calculated operator dose from 5.3 rem to 8.4 rem.

This value is still significantly below the GDC 19 thyroid equivalent limit of 30 rem.

For the above reasons, Duke Power concludes that this change does not involve a significant reduction in the-margin of safety.

l The proposed Technical Specification change has been reviewed against the criteria of 10 CFR 51.22 for environmental considerations.

As shown above, the proposed change does not i

involve significant hazards consideration or significantly l

increase individual or cumulative occupational radiation exposure.

Based on this, the proposed amendment meets the criteria given in 10 CFR 51.22 (c) (9) for categorical exclusion from the requirements for an Environmental Impact Statement.

l I

l' o

OA CO W L ROOM AREA AHU

1CRA-D-6 l

FROM YC SYSTEM 1VC50.

ll

{ d 1CPA-D-2 f

m; q

1VC6A 7"

y

'~

P s

m

,m C

y s

s s

h ~'

H y 2"

C H

ICR-D-4 1 CRA-PFTF-1 1CR-AHU-1 1CR-D-10 1CR-D-1 1CRA-PFT-1 1 CRA-D-1

)

w

[C W

IN m

~

s'o G A 1-s ICR-D-9 1CR-D-3

=-

l l

OkB p

i a

s, q

y

-Q O

I s

s j

2CR-D-9 2CR-D-3 j

I W

/

l FROM YC

)

SYSTEu h.

'O 1 r TP

'C P

o -(( dk 4

A C

A

_[

E s

1P CONTROL 2CR-D-4 1h 2

2CRA-PFTF-1 ROOM M SA-2CR-AHU-1 2CR-D-10 2CR-D-1 2CRA-PFT-1 2CRA-D-1 2CRA-D-2 2VC58 L

2CRA-D-8 ggy CONTROL ROOM VENTILATION SYSTEM (VC)

ML20077Q505

Text

Navigation menu

Search