ML20244B901

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Summarizes 820513 Telcon W/J Humphrey Re Encl on Potential Safety Issues of Mark III Containment
ML20244B901
Person / Time
Site: Grand Gulf, 05000000
Issue date: 05/18/1982
From: Houston D, Kudrick J
Office of Nuclear Reactor Regulation
To: Butler W, Schwencer A
Office of Nuclear Reactor Regulation
Shared Package
ML20234E460 List: ... further results
References
FOIA-87-40 NUDOCS 8205240024
Download: ML20244B901 (5)
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, UNITED STATES

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MAY 18 1982 Docket Nos. 50-416/417 REC E# v e n i

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MAY 2iggy met 0RANDUM FOR: A. Schwencer, Chief Licensing Branch No. 2 DL yd'I I0lhI2,1,2 A 4,5) 4 W. Butler,' Chief A Containment Systems Branch, DSI l FROM: D. Houston, Project Manager

. Licensing Branch No. 2, DL J. Kudrick, Section Leader Containment Systems Branch, DL

SUBJECT:

SUMMARY

OF MAY 13, 1982, TELECON WITH JOHN HUMPHREY -

CONCERNS ABOUT GRAND GULF MARK III CONTAINMENT On May 8,1982, John Humphrey (formerly a Containment Systems Engineer at General Electric) wrote to Mississippi Power and Light expressing his concerns as an individual about potential safety issues at Grand Gulf (Attachment 1). We obtained a copy of the letter from MP&L on May 12, 1982. As a follow-up to this letter, we contacted Mr. Humphrey on May 13 and discussed his concerns. The participants in this telecon are listed in Attachment 2.

Mr. Humphrey had worked for four years at GE on the Mark I containment system and for the past four years was the Lead Systems Engineer for Contairiment on Maric III's. He was primarily involved with the STRIDE'and GESSAR projects. His concerns for the Maric III's were based on his involvement with the STRIDE project and were not specifically identified for Grand Gulf. He assumed that certain issues might apply to Grand Gulf on the basis of containment similarity.

Mr. Humphrey had conveyed these concerns to General Electric and they were being resolved in conjunction with the GE effort supporting the STRIDE project.

However, he felt that there might be some disconnect in the resolution of these concerns on custom designed Mad ( III plants. He was particularly concerned over his perception that GE was stopping work on resolution of these issues because of the cancellation / deferral of the Hartsville and Phipps Bend contracts.

Mr. Humphrey stated his concerns for the Mark III containment as follows:

(1) LOCA Pool Swell Effects:

Structural projections, over the pool and below the HCU floor such as the steam tunnel and personnel airlock, will effect the froth break-through height. The break-through may occur at a higher

-.. elevation and the localized impact load on the HCU floor may increase g 3 gEsgf -these projections are considered. - g? . -

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. (2) Annular Space in Sleeve around SRV Discharge Line:

During the initial vent clearing phase, the additional vent area L associated with these penetrations could well act to mitigate the l

pool swell effects. However, in the steam condensation phases,

, two possible effects should be evaluated.. They are the increased l

frequency content of the resulting loads and the loading consideration on the SRV piping due to steam condensation in the vi,cinity of these l penetrations.

(3) RHR Pressure Relief Lines:

The pressure relief of the RHR heat exchangers would discharge steam  !

to the suppression pool. These relief lines terminate under the pool without a sparger-like end device. They are simple straight pipes. No load definition .for this discharge is provided  ;

in STRIDE. Some relief lines could be similar in size to an SRV.

Although the mass flux is less than an SRV, the event is similar a

. enough to merit an evaluation.

(4) Suppression Pool Temperature Response:

During a LOCA transient, there will be a significant volume of water retained within the dry well. The volume below the weir wall Will rapidly fill with water until the level reaches the top of the weir wall and then overflows past the weir wall. There is a concern that this water mass is not conservatively considered in the long term pool temperature analysis. In the short term, this mass will j be quite hot and most probably hotter than the main pool. Therefore, the STRIDE analysis treats this mass conservatively. The drywell water mass may cool considerably, however, in the long 'tenn. If this occurs, special consideration of this mass may be nectssary to yield a conservative pool temperature analysis.

(5) . Suppression Pool Stratification:

For pool temperature response calculations, an average bulk value is used without consideration of thermal gradients in the pool.

In particular, an assumption of a completely mixed pool is made during RHR operation. It appears that one should take a closer look at the pool mixing efficiency by factoring into the analysis the RHR discharge responses.

Also, specific RHR mixing tests for Perry conducted by Gilbert were di scussed. The RHR return line, as tested, was submerged 4'. If the upper pool dumps, this line would be submerged 9' to 10'.

Therefore, the applicability of these tests after pool dump should be investigated.

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(6) Spray Mode Effect on Containment Heat Removal: I Containment spray actuates automatically at 9 psid. This reduces f the flow in the RHR heat exchangers so that their effectiveness is '

diminished by 15%. The suppression pool temperature could increase ,

by 7 to 12* . The spray mode procedure mAy need manual termination )

with reset logic. Also, when RHR is in this spray mode, the system withdraws from the suppression pool with no direct return other than fallback of the spray water in the pool surface. This is less effective for pool mixing and leads to higher pool temperatures. -

(7) Drywell Bypass Leakage:

All containment analyses assume 0% leakage while 0.1 sq.ft. leakage area is allowed as a test acceptance criteria. Based on the allowed leakage area, the concerns included higher containment pressure responses, an inability to achieve a 2 psid and automatic scram, possible delay of effective operator action and possible negative effects on the hydrogen mixing system. Therefore, bypass leakage should be included in all analyses. -

(8) Containment Pressure Response:

Not discussed in detail.

(9) Effects of Upper Pool Dumping on Drywell Bypass Leakage:

The increased differential pressure across the drywell wall due to the upper pool dump was not included in the steam bypass analysis.

Mr. Humphrey freely discussed the above concerns with the staff and indicated a willingness to meet or talk to the staff at any time. He was requested to document his concerns with the NRC and he agreed to do so. He stated that he will be in Jackson, Mississippi on Monday, May 17, 1982, to discuss these matters with MP&L (Grand Gulf). After MP&L along with their contractors, GE and Bechtel, '

have had a chance to interact with Mr. Humphrey, consider the applicability of his concerns to the Grand Gulf design and perhaps, do some preliminary analyses, we plan to schedule a joint meeting with all parties in Bethesda.

As a matter pertinent to Mr. Humphrey's letter, we understand that GE has not j cancelled the STRIDE program but the overall effort has been reduced due to the indefinite hold put on the Phipps Bend and Hartsville projects. The STRIDE and GESSAR 2 projects continue.

od NY D. Houston, Project Manager Licensing Branch No. 2, DL  ;

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J drick.. Sect on Leader *

.m.V _ Co inment Systems Brtnch, D51 7 - g~

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Attachments:

As Stated

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irsoMPHREY ENGINEERING. INC.

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SWR CONTAINMENT DESIGN AND ANAi.YSIS, '-  !

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  • 15333 VIA DEil.5UR -

MONTE SERDv0.CAUFORNIA 95030

' 408 395 0467 .,.

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G1 May 8, 1982

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. Mr. L. F. Dale, Eucisar Project Manager Mississi Power and Light Coupeny . a Yp,l fhf '

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Jackson, Mississippi 39205 near Mr. nale, ..

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I have worked for General Electrie fbr almost eight years in the design l

of Mark I, II and III containments. For thb past three yearsIImet have been the

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you at the  :

j Central Electric Co. Lead Systess Engineer for Containment.,

GE/ERC asating on Mark'III 10CA loads last August. .

_ i During my work at CE in containment design a great ung technical issues '

have been bot.h identified and successnilly resolved. ' I believe the BVR-6/ Mark III l is basically an exceuent product. However as of the present However the omnesumtion of

. ,- tim l Many of these issues were being actively pursued. 3 the STRIDE Projcet has effectively terminated effort.s to resolve thes. ,

    • Because I believe that many of these issues are safety. concerns that are  ;

poteritially applicable to Grand Gulf, I could not in good conscience let them -

go mronolvod. I have resigned my position at General Ricetric nnd formed a seatsny to ensure the resolution of tim entet m< ting insper. "

'I suld sincerely appreciate an opportunity to cose and meet with ycu at ,

your earliest convenience to discuss these technical issues and to offer My l

- - company's services to evaluate their applicability to Cannd Gulf.

i Eincerely yours, ,

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John H. Musphrey, President -

  • l Humphrey Engineering Inc.-

~' ' l oct Mr. T. & Johnson ,  !

Mr. P. J. Kochis Mr. Adrian Zaccaria S030-H9-W0 m v d II Wb Bl.WWZ5B -

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! PARTICIPANTS IN TELECON L

i NRC F.,Miraglia. -

A. Schwencer-A. Butler J. Kudrick *

  • D. Houston-HUMPHREY ENGINEERING,-INC.

J. Humphrey-3 j

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