ML20062G470

Forwards Request for Addl Info Re Recent Mark III Containment Concerns.Submittal Schedule Should Be Provided within 14 Days of Receipt of Ltr

ML20062G470
Person / Time
Site:	River Bend
Issue date:	07/23/1982
From:	Schwencer A Office of Nuclear Reactor Regulation
To:	William Cahill GULF STATES UTILITIES CO.
References
NUDOCS 8208130029
Download: ML20062G470 (15)

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DISTRIBUTION:

M-2 3 1982 Document Control (50-458/459)

NRC PDR Local PDR NSIC EDechet:ilessisR50 458/450?

PRC LB#2 Reading EHylton JStefano Mr. William J. Cahill, Jr.

OELD Senior Vice President I&E River Bend Nuclear Group ACRS (16)

Gulf States Utilities Company Region IV Post Office Box 2951 Beaumont.. Texas 77704 ATTN: Mr. J. E. Booker

Subject:

Request for Additional Information - Recent Containment Concerns In the performance of the River Bend licensing review, the staff has identified concerns in regard to the recent issues about the Mark III containment. The information that we require is identified in the enclosure.

W request that you provide your schedule for submittal of this information no later than fourteen days after receipt of this letter. If you require any clarification of this request, please contact R. L. Perch, Project Manager, (301) 492-8136.

Sincerely.

A. Schwencer, Chief Licensing Branch No. 2 Division of Licensing

Enclosure:

As stated cc w/ enclosure:

See next page 8208130029 820723 PDR ADOCK 05000458 A

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Mr. William J. Cahill, Jr.

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Senior Vice President River Bend Nuclear Group Gulf States Utilities Company Post Office Box 2951 Beaumont, Texas 77704 ATTN: Mr. J.E. Booker cc:

Troy B. Conner, Jr., Esquire Conner and Wetterhahn 1747 Pennsyl vania Avenue, N. W.

Washington, D. C.

20006 l

Mr. William J. Reed, Jr.

j Director - Nuclear Licensing Gulf States Utilities Company 1

Post Office Box 2951 Beaumont, Texas 77704 Stanley Plettman, Esquire Orgain, Bell and Tucker Beaumont Savings Building Beaumont, Texas 77701 William J. Guste, Jr., Esquire Attorney General State of Louisiana Post Office Box 44005 State Capitol Baton Rouge, Louisiana 70804 Richard M. Troy, Jr., Esquire Assistant Attorney General in Charge State of Louisiana Department of Justice 234 Loyola Avenue New Orleans,' Louisiana 70112 A. Bill Beech Resident Inspector Post Office Box 1051 St. Francisville, Louisiana 70775 4

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Request for Additional Information j

on Mr. Humphrey's Concerns i

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. 1.0 Effects of Local Encro'achments on ' Pool Swell-Loads Prov{de the details of the analysis tib yields a maximum 20%

1.1 increase in pool velocity due to the TIP platform.

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1.2 The responge by Mississippi Pcwer and Light (MP&L) has not' totally.

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addressed the Humphrey concern.

The results of an analysis were in-1

-i troduced by MP&L to address the concern that local encroachment could I

cause solid slug impact above 20 feet.

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l The referenced analysis, however, was for a six foot encroachment rather than the 10 to 11 foot actual projection. ' Also, the con-servatisms noted in the analysis (proceedings page 109, lines 4 f-through 14), with the exception of the encroachment being finite-i in the circumferential direction, existed when the^ analysis was-done.with the clean pool.

Yet, the model underpredicted incipient breakthrough (nine feet vs.12 feet). The remaining conservatism, l

(finite circumfe'rential length of the encroachment), will cer-

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tainly' mitigate the effect but it cannot eliminate it. Thus, the arguments do not provide sufficient bases for dismissing the results shown to Mp5L by Humphrey on May 17th.

j Therefore, either (1) provide sound quantitative arguments as, to why these results can be dismissed; or -(2) provide realistic ex -

timates (including bases) of the maximum distance that the break-through point can move up locally as a result of the 11 foot en-croachment.

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. g 1.3 Provide the analysis and b.ases which produces the maximum, additional

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submerged loads due to encroachments.

1.4 This c'once'rn is resolved assuming a makTmum velocity of 60 ft/sec (refer to 1.1) can be established.

1.5 Response shopld be consistent 'with 1.2.

1.6 Provide the details of the analysis which shows the bounding lateral loads on grating to bb less.than the, dead weight of the structure.

2.0 Safety Relief Valve Discharge Line Sleeves 2.1 Provide documentation to support the position e:.p'ressed in the pro-ceedings that the inclusion of C.O. sources at the SRVDL sleeve exists with strength equal to 21/2% of design and at dominant frequencies approaching structural resonance does not lead to loads which exceed.

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existing design margins on the suppr~ession p6cl boundaries.

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l 2.2 Provide a detailed description of all hydrodynamic and thermal loads that are imposed on the SRYDL during LOCA blowdowns.

In addition, i

I if any of the following load conditions are not applied, provide justification for such exclusion.

(a) external pressure loads on that segment of the SRYDL eficlosed i

within the sleeve; and i

(b)' thermal loading resulting from steam flow through the' arinulus

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formed by th'e outer surface of the SRVDL and the inner surface i

of the SRVDL sleeve.

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Li 2.3 Provide a detailed description of all hydrodynamic and thermal loads l

'that are imposed on the SRVDL sleste during,LOCA blowdowns.

In ad-dition, if any of the following loading conditions are not applied, provide justifica. tion for such exclusion.

(a) "self induced" lateral loads acting on the sleeve tip as dis-tinct'from lateral loads resulting from submerged structure -

l drag consideration.

Thus, these loads would be analogous to downcomer lateral loads which are employed in the Mark I and Mark II designs; and (b) thermal loading resulting frdm steam flow though the annulus

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formed by the outer surface of the SRVDL and the inner surface of the.SRVDL sleeve.

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3.0 ECCS Relief Valve Discharge Lines Below the Suppression Pool Level 3.1 Provide the following information for the RHR heat exchanger ' relief -

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valve. discharge line and for all other relief lines that exhaust into the pool.

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(a)

Provide isometric drawings and P& ids showing line and. vacuum t

Information should include the following:

breaker location.

The geometry (diameter, routing, height above the suppression pool, etc.) of the pipe line from imediately downstream of the relief valve up to the line exit. The maximum and minimum ex-pected submergence.of the discharge line exit below the pool j

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surface should be included.

Also, if any of these lines are

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The range of flow rates and char,a,c,t,er of fluid (i.e., air, water steam) which is discharged through the line and the plant condi.

l tions (e.g., pool temperatures) when these occur;

.(c)

The sizing and performance characteristics of any' vacuum breaker i

with which these lines are equipped:

(include make, model, size

-j opening characteristics and flow characteristics).

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(d)

The potential for oscillatory operation of the relief valves. in' i

any given discharge line;

. (e) ' The potential for failure of any relief valv,e to reseat follow-ing initial or subsequent opening; and i

(f)

The location of all components and piping in the vicinity of

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the relief line exit.

3.2 Demonstrate that the steam exhaust from the RHR relief valve dischart lines will be completely condensed when the suppression pool is as its' lowest level'.

3.6 Describe the restrictions on the plant operators that prevent them from operating the RHR heat exchangers in the steam condensation mode under accident conditions.

3.7 The concerns related to the RHR heat exchanger relief valves dis-charge lines should also be addressed for all other relief lines that exhaust into the pool.

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2 5-t 3.8 Justify that vacuum breaker design is adequate to perform ' function for discharge line layout at Grand' Gulf; l

3.9 Evaluate the consequences of upper po'o'lDump with respect to flood-i ing of relief valve discharge lines and loss of pressure relief capability; and 3.10 Provide a) any supporting analyses and test results for vacuum i

I breaker performance,. dynamic loads and heat exchanger pressure; and b) basis for conclusion that heat exchangers can withstand transient i

j involving, clearing of partially flooded discharge lines.

3.11 Provide the design ba' sis for both the relief lines and equipment and piping in the vicinity of the relief line exit.

4.1 Provide the details of the bounding analysis that shows,a 17F ef-fect on suppression p,ool temperature if the water holdup in the dry-well is assumed to be isolated. -

4.2 Discuss the'effe'ct of' the throttling ECCS operation' en the accident'

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analysis provided in ',the FSAR (i.e., pool level considering upper

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pool dump).

Show that the resulting differences have no adverse effect on any ESF systems and their intended functions.

4.3 Provide the details of the analysis used to compute,the thermal stratification at the RHR heat exchanger intake and. justify all assumptions used.

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4.4 Quantify the maximum suppression pool surface temperature and the f

' resulting maximum con'tainment atm'osphere temperature and pressur'e.

Prov,tde the details of the assumptions.msed in the analysis that shows '

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a 50*-60*F temperature difference between the pool and the contain-i ment atmosphere.

4.5 Describe the effects of single failures and operator actions (e.g.,

l actuating containment sprays) on the mixing of the pool. Provide the bounding thermal stratificati,on that wculd result and its ef-4 fect on the impacted structures and systems.

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Also,' provide documentation to support the claim made in the pro-l ccedings that chugging in the Mark III. containment promotes good I

thermal mixing of the suppression pool. 'n'here appropriate, cita-1 tich of the information which has been supplied in Attachment 0 of Appendix 38 of GESSAR II would be acceptable for this purpose..

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4.6 State how long and how often the RHR system will have to operate I

to keep the suppresion pool at or below 95*F for normal operating modes.' Verify that the RHR sys, tem is designed for this type of operation ~for long periods of time.

4.7 Describe in detail the thermal and fluid flow interaction between the suction and discharge portions of the RHR system.

Show that adequate mixing will occur and that the FSAR analysis assumptions regarding this system are met.

4.8 Describe the procedures available to the operator to switch the RHR system from containment spray mode to pool cooling mode and vice e

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Quantify how much, decreased pool cooling capability exists when containment sprays are on.

Compare this decreased effective' ness '

to the assumptions used in the FSAR acalyses and provide revised analysis o'f this effect on the impacted accident sequences.

4.9 Discuss the possible effects on the long term containment response and the operability of the spray system due to cycling the contain- ~

ment sprays on and off to maximize pool cooling. Also, provide the 1

i and justify the criteria used by the operator for switching from,

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the containment spray mode to pool cooling mode, and back again.,

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Provide justification for.any margin in RHR heat. exchanger capa-4.10 city as used in FSAR pool cooling calculations that could be used to compensate for the effect of thermal stratification in pool.

In' justification, refer to applicable experimental data..for. heat exchangers such as used at Grand Gulf and provide basis for as-

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sumptions used for heat exchanger capacity.

I 5.1 During the meeting discussion on this concern, Mr. Humphrey stated '

2 that the bypass capability for an IBA was 0.1 to 0.2 ft less than s

that.for.an SBA. Describe the scenario and assumptions used in t

the Grand Gulf calculations that resulted in the conclusion that little differences existed between, the IBA and SBA results. -

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' Provide the analysis or operating experience that shows cycling l

of the containment sprays will not adversely affect its long-term l

performance.

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5.4 Provide the basis for the conclusion that hydrogen diffusing ~ through 15 the drywbil wall would mix as rapidly and not pocket anywhere as ss.,

,1 hydrogen that is pushed through the vents into the suppression pool.

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. Describe any temperature sensitive equipment that is close to the I?:

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drywell wall in the region when steam bypass is possible.

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T'he possibility of high temperatures in the drywell without reaching h@l the two psig pressure scram level because of bypass leakage through

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t-the drywell wall should be' addressed.

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p; li 6.3 Describe the location of equipment around and above the recombiners 0;J li-and shcw that high temperatures will not be seen by these. equipment.

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- equipment in the' region around and above the recombiners. State ff) h what instructions, if any, are available to the operator to actuate i.

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containment sprays to keep this temperature belcw design values.

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,r 7.1 It appears that margins due to conservative assumptions, such as the assumption of uniform temperature in the containment airspace and the ignoring of the containment structure heat sinks, are suffi-

@H cient to cover the effect. due to the ~nonconservative assumption in

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?I pool temperature.

It is noted, however, that the effects of these

q assumptions on containment pressure responses may depend on the rate

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heat ' sinks may be less sign'ificant for a very slow' and long term heating.

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Based on the material available (MP&L and J. Humphrey's presentations),

I we feel that some quantitative comparisons of the opposing effects from t

the conservative and the nonconservative assumations are desirable.

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the conservative effects are substantially more significant than that due 'to the nonconservative assumption, as expected, a very simple.com-

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parison may be sufficient. Data needed for such assessment may already be available, such as the GE analysis referred to in Item 7.2.

7.2 List and justify the assumptions used-in calculating "the environmental qualification parameters for the containment airspace.

Explain more fully the effect of using conservative' tehInical speci-8.1 fication values in the short-term and long-t'dra drywell and contain-ment pressure and temperature response.

8.2 Describe the process used to arrive at the conclusion that inadvertent eperation of containment sprays at worst initial conditions'is not credi ble.

Also, examine the effect of purge,' systems in reducing the air mass inside the containment.

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8.3 Explain how the operator's knowledge of serious conditions su'h as c

an SBA will mitigate the consequences of the accident assuming' an

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automatic scram ch~ twc psig inside the drywell does not occur.

Show that the consequences are less severe than those analyzed in the

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FSAR.

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8r4 Describe all of the possible methods both before and after an acci-dent of creating a condition of low air mass insid.e the containment..

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Discuss the effects on the containment, design external p,ressure of actuating the containment sprays.

9.1 Describe the long-term effect on the containment pressure and tempera-ture following.a DBA when the drywell air forced into the containment '

does not re-enter the drywell (i.e., operator throttling of the ECCS traps steam flowing from the break and drywell depressurization does

-' not occur.

1.2 For the analysis requested. in Q 9.1, include the effects of steam 9

bypass into the containment.

9.3 It appears that some confusion exists as to whether SBAs and stuck-open SRV accidents are treated as transients or design ba' sis acci-

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dents. Clarify how they are treated and indicate whether the initial condit.i.ons were set at nominal or most conservative values.

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10.1 - Justify the statement that'any water which spills over the weir wall i

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will do so gradually.

Include the possible effect of drywell depres-surizaticn due 'to condensation of drywell vapor from water spillage.

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i 10.2 Describe the interface requirement (A-42) that specifies that no i

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flooding of the drywell shall occur. Describe your intended methods 1

to folicw 'this interface or justify. ignoring this requirement.

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With regard to this concern, the following clarification is requested.

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The limits of drywellato-containment differential pressures which can exist in the GGNS and how these limits ar.e maintained;

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(b)

Citation.of the specific areas of.'the GESSAR II load methodol-ogy from which the effects of such differential pressures on I

SRV pool boundary of SRVDL internal pressures, pool swell loads, 1

etc. are estimated; and

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(c)

The results obtained by appli, cation of these methods to the limiting cases described in (a) above.

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2 14.

The probability argument provided is inadequate.

Using the single failure criterion and a mechanistic approach to the situation, show that either:

1) RHR operation in the_LPC1 mode will,not occur when an automatic signal is generated to actuate containment sprays; 2):

l the. contai.nment spray system can withstand any backflow and the con-i tainment design pressure and temperature will not be exceeded; or 3) j propose a design change that would eliminate this possibility.

16. -

Describe the instructions given to the operator that will allow 'him i

j to correctly use pool level instrument in conjunction with pool tem-perature instruments to follow the temperature changes in the pool.

l 19.

With regard to submergence effects on chugging loads, provide the following:

(a)

The GGNS response to this concern cites a decreasing trend of chugging loads with decreasing' vent mass flux. No such trend is identified in' the GESSAR II load definition (see Question /

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Response 38.15(b) of Attachment 0 to Appendix 38). Further l

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The GGNS response does not addressthe potential increase,in chugging leads caused by the presence of encroachments which i

" effectively" increases submergence (by increasing the distance from the chbg source to the free surface - see p. 252 of the s

proceedings).

A response to this can'cern is required as well, 19.2, -

The effect of local encrocchments on chugging loads needs to be e

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