ML19309A843

Forwards Addl Info to Part 21 Rept Re Potentially Overstressed Supports on Reactor Coolant Letdown Coolers at Facilities Under Const by B&W

ML19309A843
Person / Time
Site:	North Anna, Midland, Bellefonte
Issue date:	03/03/1980
From:	Taylor J BABCOCK & WILCOX CO.
To:	Stello V NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
Shared Package
ML19309A837	List: ML19309A836 ML19309A843
References
REF-PT21-80-199-000 NUDOCS 8004010404
Download: ML19309A843 (6)

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no; re 4.r.c" F rchn:d3)M40  :'80 fir. Victor Stello, Director .

Office of inspection r.d  : Enforcem:nt ..

U. S. I!uclear I:egulatory Con:nission .

, ifashington, DC 20555

Subject:

10 CFR 21 Report Dear Mr. Stello; }

Pursuant to the recuirer.0nts of 10 CFR 21, BD! made a telephone  !

report tu Mr. Doug Thompson of your office at 1:20 FF., February 28, 1980  :

concerning a defect reportable under 10 CFR 21. The deie:t concerns -

potentially overstressed supports on reactor cociant let-dcrin. coolers ,

at the Bcilefonte, North Ar.na and Midland Units undcr constructicn by Dcl. The responsible officer in BM', Mr. J. H. MacMillan, Vice-P.resid2nt, l'PG3, was informed of this reportable defect on February 26, 1980. -

A report providing additional information en this concern is

attached herewith. ,

Should you recuire further information, please contact Mr. David Mars  !

of my staff, (Ext. 2852). l i~~ Wrf t ruiyM)out% ' ;==

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Mr. R. D. Corsurit - DM! Dethesda Representative cc:

Mr. J. fl. MacMillan - Vice-President - !PGD -

Attach:nent - As stated .

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Report on Safety Concern RE: ' Letdown Cooler Supports -

Introduction -

This report evaluates the concern that supports for letdown coolers

. may be inadequate. This concern was initially reported on February 8,1979 and evaluated on March 15, 1979; at that time sufficient information on -

the support designs at Batl plants was available only to complete the .

cvaluation for the t.'llP-1 and 4 Units of I.'PPSS and a determination was made that the supports for those coolers was inadequate and that the condition was reportable under the requirements of 10 CFR 50.55 (e). In due course, H'P PSS was nott fled of the deficiency and they, i,n turn, notified the NRC. ..

l Eorrective action has now been completed for these units, t Investigation of the remaining DSW plants utilizing this type of

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cooler (manufactured by Atlas Industrial Manufacturing Ccmpany) has now been c

~ i, completed and it is concluded that a reportable defect as defined by I 10 CFR 21 exists for the Bellefonte Units 1 and 2 of TVA, for the North i Anna Units 3 and 4 of VEPCo and for the Midland Units 1 and 2 of Consumers.

Description of Concern .

There are two letdown coolers in the Makeup and Purification System, both in service urder normal operation. Reactor coolant letdown is cooled by these coolers prior to leaving the containment. Ilhile designing the support  !

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platforms for the WPPSS coolers, the architect engi :c : e..pr essed a concern

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about the adequacy of thEse supports. . This, concern '!as e =minnIby~ B&'J. _

Atlas and Dynatech (who perfoms stress anaivsis for c .tias), . r+ it ua ;

agrLu oy all parties that the combination of the A C'3 ap;.Ori. platform l and the cooler's support bracket would result in an overstressed condition in the lowest of the three cooler supports. The safety implication of this -

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. d;fect is that the coolcrs could be dislodged from their supports due to ~'

i the loads imposed from the letdown piping with the potential for rupturing ,

the letdown piping and releasing. reactor coolant.

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Analysis l

There are three support brackets on each cooler, each of which is attached to a corresponding support platform provided by the customer. When the coolers are installed vertically, the upper two bracket-platform combinations 'are sliding supports to allow for thermal expansion and the axial load is therefore restrained entirely by the 3rd or lowest support. The customer's support platform does not fully contact the cooler support, thereby making the cooler support bracket a cantilevered beam required to sustain moments in excess of the cooler support design; this condition is shoyn in the attached figure, In some installations, the' coolers are installed horizontally; however, the overstressed conditicn en the 3rd bracket also exists in this configuration since the major load on the bracket is from nozzle forces for both the vertical and horizontal arrangements.

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The, overstressed condition is based on the design or~ specification nozzle loads; it is conceivable that! i,f the letdown pi, ping for cach plant were analyzed, the

-. - actual loads imposed on the supports would be less than the design valces and the

support's would be adequate. However, at thi's time, no analyses have been made and

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for purposes of detennining reportability under 10 CFR 21, the fact that overstress-ing exists based on design or specification loads constitutes a deviation and a

- reportable defect. .

The Atlas coolers have been provided for the plants listed below; the status of the

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design is described for each insiiallation. i Status of Atlas Conlors for E!M f" ants i- . _

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WitP.1 a'nd 4 .f rInstallatiaa af % c:els .i. r .- found to N deficienc and

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"to be 'a reportable safei.y cuo. ern. The customers was noti-

. fied of the safety concern and the ilRC was notified by the customer. Corrective action has been completed.

Bellefonte 1 and 4 Installation of the ccolers is deficient and is a reportable

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safety concern. l 1

Installation of the coolers is def.icient and 'is a .reportabla

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?! orth Anna 3 and 4 The coolers hav,e been shipped but are not installed. The installation plan by the AE was found to have the over-t......_. - . . . . . . . , e

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Plant stressed lower support and a reportable safety concern exists. VEPC0 has reported this. condition to the f;RC

' under both 10 CFR 50, 55(e) and 10 CFR 21.

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- ' P;.bble Springs 1 and 2 The coolers have been shipped but are not installed. I The. AE has not yet developed a support design. !!o reportable concern exists. .

Rep'ortabil ity .

The inadequate supports for the coolers at Bellefonte Units 1 and 2, the North Anna Units 3 and 4 and the Midland Units 1 and 2 constitute a defect within the i

meaning of 10 CFR 21 since the letdown coolers and the connecting piping are basic s

components that assure the integrity of the reactor coolant pressure boundary and the deviation in design has the potential for creating a substantial safety hazard. [

!!ote that the defect at the UNP Units 1 and 4'has been previously reported to the ,

NRC. .. .

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-. As stated previously the over' stressed condition of the supports is.t$ased on the design or specification nozzle loads and if the loads for each plant were to be analyzed, it is possible ; hat the calculated loads on the supports would not cause cverstressing and no safety concern would exist. Ilowever, the overstressed condition based on design or specificatiot loads falls within the definition of a " deviation" ,

as given in 10 CFR 21, and furth. r, the condition satisfies the definition of a re-portable defect under 10 CFR 21. .-

T --Uhile the coolers f'or the Pebble Springs Units 1 and 2 have been shipped, the customer-suppTied support stands.have not /et been designed and therefore no reportable defect _

exists for these-coolers---

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Corrective Action ~

1. Corrective action taken for the UN. Units 1 and 4 consisted of havine.the customer re-design the customer-supplied support stand for the lowest cooler bracket.

The new design eliminates the moment by providing support for the lower support

- bracket that extends further under the bracket and therefore provides full hori-

'. 20ntal bearing; the only revision needed to .the cooler brachet is the drilling of

- three addi~tional bolt I;. oles for attachnent to th'e larger support stand. This work has been completed.

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. 2. Blal has recommended to the Bellefonte 1 and 4 units the same corrective action as described above_for the Wi:P units.

3. A course of corre'ctive action has not yet been agreed upon for the Midland Units. At this time efforts are underway to obtain the calculated nor:le load on the coolers and determine whether they are within the design values.

4. B&W has proposed to VEPC0 the same corrective action as taken for the UltP units. However, in the letter to the ilRC of January 4,1980 reporting the con-  ;

dition under the requirements of 10 CFR 21, VEPC0 states that "VEPCO has undertahen '

a study of the feasibility of utilizing the existing !? orth Anna 3 and 4 equipment and ,

- 3tructures in the design and construction of coal units. In the event that we decide  :

to continue with the construction of the !! orth Anna Units 3 and 4 as nuclear units, i we will modify the. current support ' design to eliminate the overstressed condition."

S. For the Pebble Springs 1 and 2 Units, B&W intends to provide the A/E with

.an updatcJsupport des.ign as was used in the WiiP units.. .

6. For the Erie, PASNY and DavisI B esse 2 and 3 units, the contracts to construct t

- these units ihas been cancelled and no corrective action is required'. _

7. To preclude future problems of the type described in triis report, the cooler drawings will henceforth shcw the required support arrangement to be provided by the A/E. *

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