ML20116D836

Proposed TS Sections 3.6.C & 3/4.17.B Re Reactor Coolant Equivalent Radioiodine Concentration & CR Habitability

ML20116D836
Person / Time
Site:	Monticello
Issue date:	07/26/1996
From:	NORTHERN STATES POWER CO.
To:
Shared Package
ML20116D820	List: ML20116D816 ML20116D836
References
NUDOCS 9608020345
Download: ML20116D836 (20)

Text

,

Exhibit B I

Monticello Nuclear Generating Plant License Amendment Reauest dated July 26.1996 Proposed Changes Marked Up on 'dxisting Technical Specification Pages Exhibit B consists of the existing Technical Specification pages with the proposed changes marked up on those pages. Existing pages affected by this change are listed below:

Ei!nt 123 148 229w 229x 229y 229Z n

a l

f 1

i

9608020345 960726 PDR ADOCK 05000263 P PDR

s 3.0 LIMITING CONDITIONS FOR OPERATION 4.0 SURVEILIANCE REQUIREMENTS

4. The reactor vessel head bolting studs 4.

shall not be under tension unless the When the reactor vessel head studs are temperature of the vessel head flange under tension and the reactor is in the Cold Shutdown Condition, the reactor and the head are >70*F. vessel shell flange temperature shall be permanently recorded.

• C. Coolant Chemistry C. Coolant Chemistry O 1. The steady state radiolodine concentration 1.

T (a) A sample of reactor coolant shall be N l in the reactor coolant shall not exceed / taken at least every 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> and I microcuries of I-131 dose equivalent per gram of water.

e .2 c

3.6/4.6 123 REV

Bases Continued 3.6 and 4.6

c. coolant chem!stry g(WoA afc.a g lO Yo og 4Q f ag P.& M.5oE W /

? et--47 etete rr a' ine eeneentretier li ' -f c -f I-1?1 e r;+:: lent per gren f .::ter 1-.

tb rereter ee tb r '

• . = ,/e%'dv.-system-can-bet. . r < 1... -

reached-if4he-.groce radio $tivity in the-gaseous-eff-luents-are-near oc_pr.o. longed-shutA~ . e/ th: cicanup d: 'neralizer. In the event of 'T asteamline[ruptureoutsidethedrywell,the"nc:tff at the culations show the resultant radiological dose 4 r _t c't: boundary " ) to be less than 20 ". t: th: thyrrid. This dose was calculat'ed on c' the basis of the radiciodine concentration limit of $uct of I-131 dose equivalent per gram of water, at- y L ric diff-_ icr fr a cn equi.;1cnt cl var d -r

"--quill yr. - T 1 ::ter/cc: rind ap :d cad-e-sces= l'.

ase-of-30 meter under fumiget-len-eendi-t-lene-f-er g

}

' s c la t i ca-valve-elesure-t4me--o f-Elve-s econd s y

-M o a _/- A r ...; r:1c::: cf 25,000 pounds. 1 The reactor coolant sample will be used to assure that the limit of Specification 3.6.C.1 is not exceeded.

The radiolodine concentration would not be expected to change rapidly during steady state operation over a period of 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />.

In addition, the trend of the radioactive gaseous effluents, which is continuously monitored, is a good indicator of the trend of the radiolodine concentration in the reactor coolant. When a significant increase in radioactive gaseous effluents is indicated, as specified, an additional reactor coolant sample shall be taken and analyzed for radioactive iodine.

• Whenever an isotopic analysis is performed, a reasonable effort will be made to determine a significant.

percentage of those contributors representing the total radioactivity in the reactor coolant sample.

11sually at least 80 percent of the total gamma radioactivity can be identified by the isotopic analysis.

It has been observed that radiciodine concentration can change rapidly in the reactor coolant during transient reactor operations such as reactor shutdown, reactor power changes, and reactor startup if failed fuel is present.

As specified, additional reactor coolant samples shall be taken and analyzed for reactor operations in which steady state radioiodine concentrations in the reactor coolant indicate various levels of iodine releases from the fuel. Since the radioiodine concentration in the reactor coolant is not continuously measured, reactor coolant sampling would be ineffective as a means to rapidly detect gross fuel element failures. Ilowever, some capability to detect gross fuel element failures is inherent in the radiation monitors in the off-gas system and on the main steam line.

Materials in the primary system are primarily 304 stainless steel and zircaloy. The reactor water chemistry limits are established to prevent damage to these materials. The litait placed on chloride concentration is to prevent stress corrosion cracking of the stainless steel.

3.6/4.6 148 REV

~ - y N 3.0 LIMITING CONDITIONS FOR OPERATION 4.0 SURVEILLANCE REQUIREMENTS

b. When both filter trains of the control room emergency filtration system are inoperable, restore at least one train to operable statds within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in hot shutdown within the next 12 a

hours following the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and reduce the reactor coolant water temperature to below 212* F within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

2. Performance Requirements 2. Performance Requirement Test

a. Periodic Requirements p-Combiosa

a. At least once per 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of system (1) The results of the in-place DOP operation; or once per operating tests at 1000 cfm (1101) on llEPA cycle, but not to exceed 18 months, filters shall show,4t% DOP whichever occurs first; or following -

CN penetration. C5 o,39C painting, fire, or chemical release 5F while the system is operating that p (2) The results of in-place could contaminate the llEPA filters or

> halogenated hydrocarbon tests at charcoal adsorbers, perform the LJ> following:

1000 cfm ( 10%) on charcoal banks P show A penetration.

c l 0. 3 */o (1) In-place DOP test the llEPA filter (3) The results of laboratory carbon banks.

IIJ sample analysis shall show-t964 79 mu difl todidm mmmm.ol afficicucy (2) In-place test the charcoal adsorber when tm.>tmd at 00*C, 05t R.::. banks with halogenated hydrocarbon tracer.

O r- D^

--< Cm00 ,t/ */l7,i oJ%

h A C. (~2 4 M b 1 c_s,4d- m-\- (3) Remove one carbon test canister from the charcoal adsorber.

g o 'c o.n b 95 % (d d ve- Subject this sample to a laboratory analysis to verify h omasi h s. hy. methyl iodide removal efficiency, (4) Initiate from the control room 1000 cGa (110%) flow through both trains of the emergency filtration treatment system. .

3.17/4.17 229w REV l

- _ - _ _ _ =

3.0 LIIIITING CONDITIONS FOR OPERATION 4.0 SURVEILLANCE REQUIREMENTS

b. The system shall be shown to be b.

operable with: At least once per operating cycle, but not to exceed 18 months, the following (1) Combined filter pressure drop conditions shall be demonstrated for

<8 inches wat'er. each emergency filtration system train:

(2) Inlet heater power output Skw (1) Pressure drop across the combined 10%. ~

filters of each train shall be (3) Automatic initiation upon receipt measured at 1000 cfm (i10%) flow rate.

of a high radiation signal.

(2) Operability of inlet heater at nominal rated power shall be verified.

(3) Verify that on a simulated high radiation signal, the train switches to the pressurization mode of operation and the control room is maintained at a positive pressure with respect to adjacent.

areas at the design flow rate of 1000 cfm (110%).

3. Post Maintenance Requirements 3. Post Maintenance Testing C. ombT A & b

a. After any a ntenance or testing that a. After any maintenance or testing that could affee the llEPA filter or IIEPA filter mou ing frame leak tight inte- could af fect the leak tight integrity

.grity, the esults of the in-place DOP of the llEPA filters, perform in-place

() tests at 1000 cfm (ilot) on IIEPA filters DOP tests on the llEPA filters.

yr shall show y DOP penetration, b. After any maintenance or testing that p Cc O. 3 */.

y b. After any daintenance or testing that could affect the leak tight integrity of the charcoal adsorber banks, cp could affect the charcoal adsorber perform halogenated hydrocarbon tests p leak tight integrity, the results of in-place halogenated hydrocarbon tests on the charcoal adsorbers.

DQr at 1000 cfm ( 10%) on charcoal adsorber banks shall show I penetration.

Q 3 of .

3.17/4.17 229x REV

l 3.17 Bases A. Control Room Ventilation System The Control Room Ventilation System provides air conditionig and heating as required to maintain a d

g; suitable environment in the main control room and portions ot the first and second floors of the Emergency er Filtration Train (EFT) building. Thc sain centrol roos is acraally slightly pres a-ia d ~ d it 1. <

7t: --iM  : t: 'n _ 0 - 100* r:e.r clati n of caniitbacd air. Tho-syrte-.eir desi.gned te =a4nt+1n-a-=Et u c:r tur: : f ? ? * " d ry 'm ! ' : ' 5 0' r - ' - - ! r ' " ' -- H ' ' i t- '- 6

" " e mtrel rrr- i . th: curz:r and a g

. Ami temp;r tur; cr "P 'r the r'-ter. The Control Room Ilentilation System may.be isolated from g unfiltered external air supply-by manual actior .

gj 4 g gQ All toxic substances which are stored on site or stored / shipped within a 5 mile radius of the plant have been analyzed for their affect on the control room operators. It has been concluded that the operators will have at least two minutes to don protective breathing apparatus before incapacitation limits are exceeded. For toxic substance which are transported on highways within 5 miles of the plant, it has been determined that the probability of a release from the plant due to incapacitation of the operators caused by a spill is sufficiently low that this scenario may be excluded. Protection for toxic chemicals is provided through operator training.

B. Control Room Emernency Filtration System The Control Room Emergency Filtration System assures that tlie control room operators will be ade uately protected against the effects of radioactive leakage which may y-pass secondary containment fol owing a loss of coolant accident or radioactive releases from a steam 1 ne break accident. The system is designed to isolate and slightly pressurize the control room on a radiation signal in the ventilation air Two completely redundant trains are provided.

O, Y/o Sree .h Each train has a filter unit consistin of a prefilter, IIEPA filters, and cl rcoa adsorbers. The llEPA filters remove particulates from the C ntrol Room pressurizing air and preve tc gging of the iodine adsorbers. The charcoal adsorbers are installed to remove any radiotodines the pressurizing air.

The in-place test results should indic e a llEPA filter leakage of less than hrough DOP testing and a charcoal adsorber leakage of less than - through halogenated hydrocarbon testing. The laboratory carbon sample results should indicate a radioactive methyl iodide removal efficiertcy of a least 944 nder test CD conditions similar to expected accident conditions. System flows should be near their desig values. The verification of these performance parameters combined with the qualification testing conduc d on new d filters and adsorbers provide a high level of assurance that the Emergency Filtration Syste will perform qr as redicted in reducing doses to plant personnel below those level stated in Criterion 19 5f Appendix A T to O CFR 50.

g C 99,6 *4 Dose calculations have been performed for the Control Room Emergency Filtration Syst which show that, y assuming M X standby gas treatment system adsorption and filtration efficiency and control. room emergency Lltration system adsorption and filtration r

• efficiency and radiolodine plateout, whole body and organ do es remain within the 43aG-guidelines m- ' 30 rem, respectively.

~

3.17 BASES 229y o4 iOcm50, AppA A , (rwd Oc@ bcnn 19

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. i i

4.17 Bases A. Control Room Ventilation System Control room air temperature is checked each shift to ensure that the continuous duty rating for the instrumentation and equipment cooled by this system is not exceeded. ,

Demonstrating automatic isolation of the control room using simulated accident signals assures control room isolation under' accident conditions.

B. Control Room Emergency Filtration System Air flow through the filters and charcoal adsorbers each month assures operability of the system.

The frequency of tests and sample analysis is necessary to show that the llEPA filters and charcoal adsorbers can perform as; evaluated. The charcoal adsorber tray is installed which can accommodate a sufficient number of representative adsorber sample modules for estimating the amount of penetration the system adsorbs though its life. Sample modules will be installed with the same batch characteristics g as the system adsorbent and will be withdrawn for the methyl iodide ~ removal efficiency tests. Each module g3 4 withdrawn will be replaced or blocked off.

In-place testing procedures will be established utilizing T '

applicable sections of Regulatory Guide 1.52, Revision 2 and ANSI N5104960- standards as procedural l4 guidelines only. If test results are unacceptable, all adsorbent in the Any llEPA filters found defective are replaced. rain lg9 is replaced.k i Pressure drop across the combined IIEPA filters and ' charcoal adsorbers of less than 8 inches of water at the system design flow rate will indicate that the filters and adsorbers are-not clogged by excessive amounts of foreign matter.

Demonstrating automatic control room pressurization using simulated accident signals assures control. room pressurizacion with respect to adjacent areas under accident conditions.

5 4 W pbu- PeacArdo^ 44shg 4- 444 fjEPA 4;Ru3 mh DOP Oe HEM 4 %<s, v,p34v % gA clov,g sh %. _

oC -de- ebco d ods.o- bce.3- m. Me_A ied'widually w i 3 + he- inchviAuM +:s+5 +6 -(ta 4 0 <c.1 *af 8 + A ,"

g <,A\u4 Me. e441cio </v o4 46 + w a (fCPA 434c6 ;^ co M dion +o sdidy Cri\c3'iA 4.17 BASES

/ 229z REV of O gcM; c. CAM %s.

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_ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ __--_______m _____._.____m_ -.-._.__.____m . . _ _ _ . ___

I l

I Exhibit C Monticello Nuclear Generating Plant License Amendment Reauest dated July 26.1996 Revised Technical Specification Page:

l Exhibit C consists of the Technical Specification pages with the proposed changes l incorporated. Existing pages affected by this change are listed below: .

)

ED.QR

! 123 l l

148 229w 229x 229y 229Z l

I 4

P Y

f

3.0 LIMITING CONDITIONS FOR OPERATION 4.0 SURVEILIANCE REQUIREMENTS

4. The reactor vessel head bolting studs 4. When the reactor vessel head studs are shall not be under tension unless the under tension and the reactor is in the temperature of the vessel head flange Cold Shutdown Condition, ^he reactor and the head are 270'F. vessel shell' flange temperature shall be permanently recorded.

C. Coolant Chemistry C. Coolant Chemistry

1. The steady state radioiodine 1. (a) A sample of reactor coolant concentration in the reactor coolant shall be taken at least shall not exceed 2 microcuries of I-131 every 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> and dose equivalent per gram of water.

3.6/4.6 123 REV

~ . .. - - _ - . .. . .. _ - - - . - . . _ . . - ~.~.- --

Bases Continued 3.6 and 4.6 C. Coolant Chemistry In the event of a steam line rupture outside the drywell, calculations show the resultant radiological dose at the exclusion area boundary to be less than 10% of the dose guidelines of 10CMt100. This dose was calculated on the basis of the radioiodine concentration limit of 2 pCi of I-131 dose equivalent per gram of water.

The reactor coolant sample will be used to assure that the limit of Specification 3.6.C.1 is not' exceeded. The radiciodine concentration would not be expected to change rapidly during steady state.

operation over a period of 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br />. In addition, the trend of the radioactive gaseous effluents, which is continuously monitored, is a good indicator of the trend of the radiciodine concentration in the reactor coolant. When a significant-increase in radioactive gaseous effluents is indicated, as specified, an additional reactor coolant sample shall be taken and analyzed for radioactive iodine.

Whenever an isotopic analysis is perforced, a reasonable effort will be made to determine a significant percentage of those contributors representing the total radioactivity in the reactor coolant sample. Usually at least 80 percent of the total gamma radioactivity can be identified by the isotopic analysis.

It has been observed that radiciodine concentration can change rapidly in the reactor coolant during transient reactor operations such as reactor shutdown, reactor power changes, and reactor startup if failed fuel is present. As specified, additional reactor coolant samples shall be taken and analyzed for reactor operations in which steady state radiciodine concentrations in the reactor coolant indicate various levels of iodine releases from the fuel. Since the radiciodine concentration in the reactor coolant is not continuously measured, reactor coolant sampling would be ineffective as a means to rapidly detect gross fuel element failures. However, some capability to detect gross fuel element failures is inherent in the radiation monitors in the off-gas system and on the main steam line.

Materials in the primary system are primarily 304 stainless steel and zircaley. The reactor water chemistry limits are established to prevent damage to these materials. The limit placed on chloride concentration is to prevent stress corrosion cracking of the stainless steel.

3.6/4.6 148 REV

i 3.0 LIMITING CONDITIONS FOR OPERATION 4.0 SURVEILULNCE REX 2UIREMENTS

b. When both filter trains of the control room emergency filtration system are '

inoperable, restore at least one train to-operable status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> following the 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and reduce the reactor coolant water temperature to  ;

below 212*F within the following 24  :

hours.

2. Performance Requirements 2. Performance Requirement Test .

a. Periodic Requirements a. At least once per 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of system '

operation; or once per operating cycle. l' (1) The combined results of the in- but not to exceed 18 months, whichever place DOP tests at 1000 cfm (i101) occurs first; or following painting, i

l on HEPA filters shall show <0.3%

fire, or chemical release while the DOP penetration. system is operating that could- .

contaminate the HEPA filters or charcoal  ;

(2) The results of in-place adsorbers, perform the following:

halogenated hydrocarbon tests at (1) In-place DOP test the HEPA filter  ;

1000 cfm ( 101) on charcoal banks show <0.3% penetration.

banks. j i

(3) The results of laboratory carbon (2) In-place test the charcoal adsorber sample analysis shall show the banks with halogenated hydrocarbon methyl iodide penetration _<0.4% tracer.

when test at 30*C and 95% relative humidity. (3) Remove one carbon test canister from .

the charcoal adsorber. Subject this i sample to a laboratory analysis to i verify methyl iodide removal i efficiency.

(4) Initiate from the control room 1000 cfm *

( 10%) flow through both trains of the emergency filtration treatment system.

i 229w 3.17/4.17 REV [

.- , - - , - - -s ..me. v- .n s+m. ~

3.0 LIMITING CONDITIONS FOR OPERATION 4.0 SURVEILIANCE REQUIREhENTS

b. The system shall be shown to be b. At least once per operating cycle, but operable with: not to exceed 18 months, the following conditions shall be demonstrated for (1) Combined filter pressure drop $8 each emergency filtration system trein:

! inches water.

(1) Pressure drop across the combined (2) Inlet heater power output Skw i filters of each train shall be 10%. measured at 1000 cfm (110%) flow rate.

(3) Automatic initiation upon receipt of a high radiation signal. (2) Operability of inlet heater at nominal rated power shall be verified.

i (3) Verify that one simulated high radiation signal, the train switches to the pressurization mode of operation and the control room is maintained at a positive pressure with respect to adjacent areas at the design flow rate of 1000 cfm (110%).

3. Post Maintenance Requirements 3. Post Maintenance Testing

a. After any maintenance or testing that a. After any maintenance or testing that

, could affect the HEPA filter or HEPA could affect the leak tight integrity of filter mounting frame leak tight the HEPA filters, perform in-place DOP integrity, the combined results of the tests on the HEPA filters.

in-place DOP tests at 1000 cfm (i10%) on HEPA filters shall show $0.3% DOP b. After any maintenance or testing that penetration. could affect the leak tight integrity of the charcoal adsorber banks, perform-

b. After any maintenance or testing that halogenated hydrocarbon tests on the could affect the charcoal adsorber leak charcoal adsorbers.

tight integrity, the results of in-place halogenated hydrocarbon tests at 1000 cfm ( 10%) on charcoal adsorber banks shall show $0.3% penetration.

l 3.17/4.17 229x REV

3.17 Bases A. Control Room Ventilation System The Control Room Ventilation System provides air conditioning and heating as required to maintain a suitable environment in the main control room and portions of the first and second floors of the Emergency Filtration Train-(EFT) building. The Control Room Ventilation System may-be isolated from unfiltered external air supply by manual action or by automatic actuation due to high radiation.

All toxic substances which are stored on site or stored / shipped within a 5 mile radius of the plant have been analyzed for their affect on the control room operators. It has been concluded that the operators will have at least two minutes to don protective breathing apparatus before incapacitation limits are exceeded. For toxic substance which are transported on highways within 5 miles of the plant, it has been determined that the probability of a release from the plant due to incapacitation of the operators caused by a spill.is sufficiently low that this scenario may be excluded. Protection for toxic chemicals is provided through operator training.

B. Control Room Emerstency Filtration System The Control Room Emergency Filtration System assures that the control room operators will be adequately protected against.the effects of radioactive leakage which may by-pass secondary containment following a loss of coolant accident or radioactive releases from a steam line break accident. The system is designed to isolate and slightly pressurize the control room on a radiation signal in the ventilation air. Two completel.y redundant trains are provided.

Each train has a filter unit consisting of a prefilter, HEPA filters, and charcoal adsorbers. The HEPA filters remove particulates from the Control Room pressurizing air and prevent clogging of the iodine adsorbers. The charcoal adsorbers are installed to remove any radioiodines from the pressurizing air.

The in-place test results should indicate a HEPA filter leakage of less than 0.3% through DOP testing and a charcoal adsorber leakage of less than 0.31 through halogenated hydrocarbon testing. The laboratory carbon sample results should indicate a radioactive methyl iodide removal efficiency of a least 99.6% under test conditions similar to expected accident conditions. System flows should be near their design values. The verification of these performance parameters combined with the qualification testing conducted on new filters and adsorbers provide a high level of assurance that the Emergency Filtration System will perform as predicted in reducing doses to plant personnel below those level stated in Criterion 19 of Appendix A to 10 CFR 50.

Dose calculations have been performed for the Control Room Emergency Filtration System which show that, assuming 851 standby gas treatment system adsorption and filtration efficiency and 981 control room emergency filtration system adsorption and filtration efficiency and radiciodine plateout, whole body and organ doses remain within guidelines of 10CFR50, Appendix A, General Design Criterion 19.

3.17 BASES 229y REV

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w444, g.-45 4m ..si. 4 a - * - - - - - - - ' - - - - - - - - ' ---- -----~'------'-------'-----'-------:-- ' - ' - - - - - ' ' - - - - - - - - - ' - - - - ' - - ' - ' ' - - - - - - - ' - - - - ' - - - - - - - - - ' - - - ' ' - - ' ' - - - - * - - - - - - ' ' - - - - - - - ' " - - - - - - - - ' -

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4.17 Bases A. _ Control Roon Ventilation System Control room air temperature is checked each shift to ensure that the continuous duty rating for the instrumentation and equipment cooled by this system is not exceeded.

Demonstrating automatic isolation of the control room using simulated accident signals assures control room isolation under accident conditions.

B. Centrol Room Emerrency Filtration System Air flow through the filters and charcoal adsorbers each month assures operability of the system, i The frequency of tests and sample analysis is necessary to show that the HEPA filters and charcoal adsorbers can perform as evaluated. The charcoal adsorber tray is installed which can accommodate a sufficient number of representative adsorber sample modules for estimating the amount of penetration the system adsorbs though its life. Sample modules will be installed with the same batch characteristics as the system adsorbent and will be withdrawn for the methyl iodide removal efficiency tests. Each module withdrawn will be replaced or blocked off. In-place testing procedures will be established utilizing applicable sections of Regulatory Guide 1.52, Revision 2 and ANSI N510-1989 standards as procedural guidelines only. If test results are unacceptable, all adsorbent in the train is replaced. For in-place penetration testing of the HEPA filters with DOP, the HEPA filters upstream and downstream of the charcoal adsorbers are tested individually, with the individual tests then factored together to reflect the efficiency of the two HEPA filters in combination to satisfy the criteria of the specifications. Any HEPA filters found defective are replaced.

Pressure drop across the combined HEPA filters and charcoal adsorbers of less than 8 inches of water at the system design flow rate will indicate that the filters and adsorbers are not clogged by excessive amounts of foreign matter.

Demonstrating automatic control room pressurization using simulated accident signals assures control room pressurization with respect to adjacent areas under accident conditions.

4.17 BASES Page 229z REV

=

l' Exhibit D i i Monticello Nuclear Generating Plant f l License Amendment Reauest dated July 26.1996 MNGP MSLBA Evaluation Summary L

The radiological evaluation of the main steam line break accident (MSLBA) is described in USAR Section 14.7.3.

Assumptions

( The postulated accident involves a guillotine break of one of the four main steam lines outside ,

l of the containment, resulting in mass loss from both ends of the break. There is no fuel 1 damage as a consequence of this event, therefore the only activity released to the environment is that associated with the steam and liquid discharged from the break. Initially

(.

only steam willissue from the broken end of the steam line. Subsequently, rapid depressurization due to the break causes the reactor pressure vessel water level to rise, resulting in a steam-water mixture flowing from the break until the main steam isolation valves (MSIVs) are closed. For the MSIV ciosure time, an analysis input of 10.5 seconds after the MSLBA is used. Activity associated with the discharged coolant is airbome in the turbine ,

building instantaneously and released to the environment without delay.

I i

l The analysis assumes that the accident occurs at hot standby conditions. At these conditions, l steam generation from the decay heat in the core is very low and cannot make up the steam i L loss through the break. The results are a high rate of vessel depressurization and rapid rising of water level to the main steam line inlet. In addition to hot standby conditions, the 10CFR50 Appendix K break flow model was assumed in order to maximize the two-phase break flow rate. Both of these assumptions yielded the maximum coolant mass releases through the break.

Two cases were analyzed. The first case assumes reactor pressure is at the safety relief valve opening setpoint of 1158 psia. The second case assumes the initial reactor pressure is at the pressure regulator setpoint of 965 psia. The results show that the mass leaving the reactor pressure vessel through the break is 71,574 lbm of liquid and 4,030 lbm of steam for the first l case. In the second case the mass leaving the reactor pressure vessel through the break is 66,223 lbm of liquid and 4,243 ibm of steam.

Accident parameters relevant to the radiological analysis are summarized in Table D-1. The atmospheric dispersion factors to tne site boundary and to the control room intake, as well as control room parameters, are included in Table D-1, l

4 i

A Noble Gas Concentration The assumed noble gas activity is the Monticello Technical Specification limit which corresponds to an off-gas release rate of 0.26 Cl/.tec (rounded to 0.3 Ci/sec in the USAR) at

30 minutes delay. This activity is assumed to cons'st of a standard isotopic fraction.

l lodine Concentration i The analysis used an input of 2 pCi/g dose-equivalent of I-131 for the activity in the coact'ar coolant. A portion of the released coolant exists as steam prior to the accident. Therefore,ius necessary to separate the initial steam mass from the total mass released and assign a certain percentage of the fission product activity contained in this portion of the steam by an equivalent mass of reactor coolant. A 2% carryover ratio was assumed for the analysis.

l Offsite Dose and Control Room Dose Evaluations Activities released to the environment due to the MSLBA are calculated for both hot standby conditions. The case for reactor pressure at the safety relief valve opening setpoint and the case for reactor pressure at the pressure regulator setpoint. In addition, the analysis was performed for coolant concentrations based on both the TID-14844 and Regulatory Guide 1.109 thyroid dose conversion factors.

Offsite dose consequences are presented in Table D-3.

l Control room dose consequences are presented in Table D-4.

l i

i D-2 I

r t

l TABLE D-1 Assumptions for MNGP MSLBA Analysis PARAMETER VALUES Power Level Hot standby at 4% power (68.8 Mwt)

RPV Pressure (psla)

Case 1 1158 Case 2 965 Time Elapse for MSIV Full Closure (seconds) 10.5 Fuel Rod Damage O Mass of Steam-Water Mixture Leaving Break (Ibm) See Table D-2 Reactor Coolant Dose Equivalent 1-131 ( C1/g) 2 lodine Carryover Factor (%) 2 lodine Releases ( C1/cm ) For Total Release See Table D-2 TID-14844 l-131 0.77 l-132 3.38 l-133 2.85 l-134 7.27 l-135 2.56 Reg. Guide 1.109 l-131 1.08 l-132 4.72 1-133 3.98 '

l-134 10.2 l-135 3.58 I Thyroid Dose Conversion Factors (rem /Ci) 1-131 1.08E+06 l-132 6.44E+03 1-133 1.80E+05 l-134 1.07E+03 1-135 3.13E+04 l

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D-3

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l TABLE D-1 (continued)  !

l Assumptions for MNGP MSLBA Analysis l

PARAMETER VALUES Data for Control Room Volume of Control Room (ft*) 27,000 Filter Intake (cfm) 900 Efficiency of Charcoal adsorber(%) 98 Unfiltered inleakage (T < 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />) (cfm) 250 Unfiltered inleakage (T > 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />) (cfm) 10 Occupancy Factor 0 - 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 1.0 1 - 4 days 0.6 4-30 days 0.4 Control Room Intake Atmospheric Dispersion Factors (sec/m')

l Ground Level Release 0 - 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> 1.67E-03 8 -24 hours 1.41E-03 1 - 4 days 9.65E-04

! 4 - 30 days 5.62E-04 Offsite Atmospheric Dispersion Factor (sec/ m')

Ground Level Release I

0 - 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> (EAB/LPZ) 9.20E-04/7.93E-05 2 - 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> (LPZ) 7.93E-05 8 -24 hours 5.35E-05 1 - 4 days 2.28E-05 4 - 30 days 6.08E-06 l

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D-4

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, I l TABLE D-2 1 l

Mass Release From MSLBA (Ibm) CASE 1 CASE 2 Totalliquid released through break

)

71,574 66,223 i Liquid released flashing to steam 10,548 8,151 Initial steam prior to steam line covered 4,030 4,243 l lodine Release From MSLBA (Cl)

! TID-14844

l-131 28.8 26.2 l 1132 126 114 l-133 106 96.3 1-134 271 246 l-135 95.6 86.6 Reg. Guide 1.109 l-131 40.2 36.4 l-132 176 160 '

! l-133 148 135 l l-134 379 343 I

l-135 134 121 l

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.-, _ - . - - -- .a. a- , .-u_ . ,- a-.a TABLE D-3 MNGP MSLBA Offsite Dose (REM) 2 - Hour Exclusion Area Boundary 30 Day Low Population Zone TID-14844 DCF Thyroid Whole Body Thyroid Whole Body Case 1 17.3 0.28 1.49 0.02 Case 2 15.7 0.26 1.35 0.02 Reg. Guide DCF Case 1 24.2 0.40 2.08 0.03 Case 2 21.9 0.36 1.89 0.03 10CFR100 300 25 300 25 TABLE D-4 MNGP MSLBA Control Room Dose (REM)

Thyroid Whole Body TID DCF Case 1 7.26 0.003 Case 2 6.58 0.002 Reg. Guide DCF Case 1 10.1 0.004 Case 2 9.18 0.003 GDC 19 30 5 D-6