ML20094J527

Forwards Response to NRC 840522 Request for Addl Info Re SER Outstanding Issue 9 & Confirmatory Issues 13 & 71 Re Suppression Pool Hydrodynamics

ML20094J527
Person / Time
Site:	Clinton
Issue date:	08/08/1984
From:	Herborn D ILLINOIS POWER CO.
To:	Schwencer A Office of Nuclear Reactor Regulation
References
L30-84(08-08)L, L30-84(8-8)L, U-0727, U-727, NUDOCS 8408140351
Download: ML20094J527 (6)

Text

• . .,

U- 0727 0982-L L30-84(08-08 4 ILLINDIS POWER COMPANY IP CLINTON POWER STATION. P.o. BOX 678. CUNTON. ILUNOIS 61727 August 8, 1984 Docket No. 50-461 Director of Nuclear Reactor Regulation Attention: Mr. A. Schwencer, Chief Licensing Branch No. 2 Division of Licensing U. S.. Nuclear Regulatory Commission Washington, D. C. 20555 Subj ect: Clinton Power Station Unit 1 SER Outstanding Issue #9 SER Confirmatory Issues #13, #71 Suppression Pool Hydrodynamics

Dear Mr. Schwencer:

On April 18, 1984 Illinois Power met with the NRC Containment Systems Branch staff in Bethesda, Maryland to discuss the subject of suppression pool hydrodynamics. This meeting resulted in the issuance of an NRC letter to CPS dated May 22, 1984 requesting additional information. Attached is the supplemental information requested. We believe that this information will resolve your specific concarns on this issue.

Phase contact us if you have any questions concerning the attached information.

Sincerely yours, Daniel I. Herborn '

Director - Nuclear Licensing and Configuration Nuclear Station Engineering KAB: lam Attachment cc: B. L. Siegel, NRC Clinton Licensing Project Manager NRC Resident Office Regional Administrator, Region III, UCNRC Illinois Department of Nuclear Safety Mk B408140351 840008 PDR ADOCK 05000461 E pag

N;. O -.

1. ' I* Attachment-

~

LThe following are the NRC questions asked in the ' April 18, 1984

~

meeting with its corresponding response.

4

-Question #1:

t- :IPC's response to the NRC question 480.28 (

Reference:

Letter:U-0698 dated February 17, 1984) 'should be modified to include.the specific equipment which would

.be.used for alternate shutdown cooling capability in the event of. suction line failure.

Response

Alternate shutdown cooling is accomplished by depressurizing.the reactor and supplying cooling water from the suppression pool to the vessel by any available ECCS. The water is then returned to the suppression pool via any of the safety / relief valve discharge lines, and the decay heat will be-removed by operation of the suppression pool cooling mode of the RHR system. The response to NRC question 480.28 will be revised to reflect this.

Questionif2:

Evaluate the Clinton facility using.the latest acceptance criteria contained in, draft NUREG-0978 currently out for public comment rather than the 1982 decision.

. Response:

Significantichanges.to the Appendix C acceptance criteria are modification of-Section 1.3 to remove the methodologies:for determining _ impact loads on.short-structures or structures within six feet of the

.suppressionipool surface. -With.this deletion, CPS would no longerchave a documented methodology for determining impact loads on these. structures..

Therefore, structures such as supports for the RHR and RCIC systems and structural steel supporting grating

above the suppression pool would have to be reviewed by-the NRC on a case-by-case _ basis for these impact loads.

Section 1.4 was' modified to allow a reduction in froth' impact loads for structures and components above the floor grating. This could provide for some load reliefs however,.our current. design is-capable of withstanding the original load and is,'therefore, conservative.

Section 3.0 has been added'to the draft NUREG-0978 b~ acceptance criteria which specifies a design methodology.for weir swell-(reverse pool swell) phenomena. A load definition, using a methodology

' $ ' $51 .

Page 2 similar to that used in GESSAR, has been developed for CPS ~. A description and justification for this methodology was provided to the NRC in February (Letter

-No. U-0698) and is under review.

QuestionL f3:

State which1 revision of GESSAR-II Appendix 3B is being .

referenced for Clinton, and state how changes to the GESSAR document are incorporated into the design .

verification of CPS.

- Response:

. CPS uses GE Document #22A7000 (through Revision 2, dated June 12, 1981) as the design basis for SRV and.

LOCA hydrodynamic loads. As revisions are transmitted by GE for use on Clinton.. appropriate evaluations are performed.as to the extent and impact of the changes.

The revisions are then assessed based upon' relevance of the change to CPS, schedule and other information. The overall merits of the revision are then assessed to ,

determine whether or not the revision will be

~ implemented.

. Question #4:

Provide details behind the 4.6 psid froth drag load

~

-calculation and the reason for applying the calculation from GESSAR for this phenomena.

Response

.The;GESSAR definition Lof- ll psid.'across the HCU floor,-

~3 as a' result of wetwell froth pressurization, is to be _

1 applied to the total annulus. area at the'HCU floor with

. Jan; appropriate dynamic load factor. Because of.this,- '

the-load governed the design of; structural steel at~the

, -HCU floor inLmanyLeases. 'A reduction was sought to minimize the design-loads'and eliminate potential

_ design; modifications.

1 The' pressure ~ differ.ential'of-4.6 psid across the HCU floor was calculated using the proprietary General-Electric: Containment Analytical Model. The Clinton HCU floor consists of concrete slab-sections, grating and

, 'open area.; The calculation wasLbased upon the HCU elevation being 26% open. The open area for Clinton is at least 26% of-the-totalJ area, therefore, the 4.6 psid specification is conservative.

Using a 6P.of 11 psid,' structural steel at the HCU

, ' floor would be governed by this load. However, the reduced /SP of:4.6 psid governs only the" grating design.

u s N /

• v .e+~,v= ee,-e, ,,,,-ww -e,-o,-e,,

O, g, .

S ^

-Page 34

~

P- Question $5:

Review FSAR= Sections ~A3.8 and A3.9 for compatability

!with1GESSAR-II and: identify where revisions are

' required.

sResponse:

For FSAR Section A3.'8,ithe following differences are noted: -

1 1.. Section'A3.8.3.1 presents the-Clinton calculated peak ~LOCA bubble pressure to be 20.1-psig. This value was based on FSAR analyses and is lower than the'21.8 psig specified in.GESSAR-II.

L Subsequently, .this analysis was revised for the~

FSAR and the pressure-value was reduced to 18.9 psig. The FSAR may be revised to denote the_ CPS ,

"' specific value of 18.9 psig, but it is intended to c

use the cons (rvative 20.1 psig value as the design. -

-basis.

2. Section A3.8.3.4.5 requires revision to remove the -

11 psid drag load on the HCU floor,specified in -

GESSAR-II and insert the. CPS specific drag load of 4.6 paid based on GE calculations.

3. Section A3.8.3.4.7.2-requires revision to correct the specification of the global prechug under-pressure spatial distribution by. deleting-the words "Mean Underpressure" from the title of FSAR-Figure A3.8-37. Also, Figure;3B-34 from GESSAR-II should be added as a reference to the FSAR.

7 4 .- Figure A3.8-30 should be revised to correct the reference to A3.8-6.-

+ .

For FSAR Section A3.9, the following differences'are noted: '

1. Section A3.9.3.1.2 states that- water j et loads do not apply to submerged structures. This should be revised to state that only the quencher device is subject to water jet loads.- GE has addressed this ,

load in Section 3B0.3.2.31 of GESSAR-II. .

2. Section A3.9.3.2.2 indicates that effects of x interference and unsteady flow are included in the design basis where:they increase the loads described in GESSAR-II._ This is a conservatism included in the CPS design that is not explicitly mentioned in GESSAR-II.

t r-

, , , , , ,,-,w .-, .~~~.a---,n.n--,--n,,,-,n , - .-- -,,..---,.n, ,,_,,.a.,,-_.,.-,-r,-- -m-.- ,n-,-- n.,-e, , . , -, , - -

k Jk _t-

.j

-e-Page 4

, 3. ' Figure.A3.9-8 should be revised to correct Note 3 by revising the reference to Figure A3.8-18 from Figure A3.8-7. Also, on the abscissa, the elevation for the

-transition zone shall be corrected from 22.5 ft, to 19.0 ft.

The'above revisions will be implemented in a future FSAR change.

--Question #6:

a) Justify why CPS has used the pool swell shape, as

, . predicted by the GE-performed SOLA analyses, to

, make. modifications.to the present encroachments

, (i.e.. extending the existing structure further

away from the drywell wall over the suppression 4

pool).

F b) Justify the use of 115 psi as the impact load for beams used on the 737' elev. floor extension over

, the suppression pool.

Response

i o a) Illinois Power has-transmitted the justification l' for the encroachment extension as part of the i= .Humphrey' Issues. (Reference Letter U-0714, D. I..

Herborn (IP) to A. Schwencer (NRC), dated May 25, 1984). As a member of the Containment Issues Owners Group, (CIOG), Illinois Power's involvemen't to resolve the validity crf SOLA.is still in progress.

The encroachment modification at 737?-0" elev. of.

~

b)-

4-the containment-has been designed-for a 115 psi-

_ impact load. The exposed surfacesoof the b, encroachment's S-sections, C-sections,-and the the

C-sections are illustrated plates supported in Figure by hed).

l.0 (attac As shown,'all the widthsoof these exposed-sections are less than-20". 'Therefore, these sections.were desi

.the load definition'of "small' structures,gned to

. which' (1 is 115; psi.

s JLP/jkp/ MISC 19-L.

7 N

w s

f .

. i e I paf.m-

.; t s;, *

'r. [ .,

e G

_m-lf crrn 1 2! t' * ,'

\ Mirns

. . - U. & fft  %'O MYP)

) .

j jf i/

N[z

.. :: .s.

, Ni A .

PLAN 2)/" ..

), j f'/ ff ,W f/ ll ? I ? l# l' Il ;

ig.. ,., y 4 ,

m SECTION FIGURE 1.0 .

L .

L_.