ML20011A621

Updated LER 81-007/01T-1:on 810122,potential Modeling Error in ECCS Model Used for LOCA Analysis Reported.Caused by Shift in Peak Clad Temp.New ECCS Analysis Performed in Aug 1981.No Impact on Public Health & Safety

ML20011A621
Person / Time
Site:	Robinson
Issue date:	10/20/1981
From:	Starkey R CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20011A619	List: ML20011A618 ML20011A621
References
LER-81-007-01T, LER-81-7-1T, NUDOCS 8110290192
Download: ML20011A621 (3)

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NRC FORM

36611pdate Report Frevious Report ' ate February 27, 1981U. S. NUCLEAR REGULATORY COMMISSION

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LICENSEE EVENT REPORT

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EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h 0 2 lOn January 22, 1981, Westir; house notified Carolina Power and Light of a potential l g o ;3, lmodeling error in the ECCS model used for LOCA analysis. On February 12,11981, a l

o p j l preliminary analysie determined that although~this error resulted in a shift in peak l o 3  ; clad temperatures, this shift was more than adequately compensated for by margins U g.

- fo is l l demonstrated .in a previously submitted ana' lysis. This event is reportable pursuant

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' 33 34 3b M 31 40 di 42 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS 27 111 O I lA r.ew ECCS analvsis was nerforced in Aueust. 1981. which showed that the new ECCS l Lt. Li J . liniection locations do not recuire any chance to the renctor nnforv limite c urron t- 1 v  !

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i 2 lin use at HBR2. It is, therefore, concluded that this error did not result in any l-lil3l l potential adverse impact to the public health and safety. l l1 14l l l 7- 8 9 00 ST S  % POWER OTHER STATUS IS OV RY DISCOVERY DESCRIPTION I115I [hj @ l0 l9 l6 lhl N/A l l Dl@l Notification-From NSSS l ACTIVITY CO TENT RELEASED OF RELEC 4 AMOUNT OF ACTIVITY .

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1 8110290192 811020 68 69 80 s gDRADOCK05000h -R. B. Starkey, Jr. PHONE: (803) 383-4524 ' E,

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- On January 22, 1981, k'estinghouse notified Carolina Power and Light of a potentia.'

modeling error in. the ECCS model used for LOCA analysis. On February 12, 1981, a preliminary analysis determined that although this error res'ulted in a shif t in peak clad temperatures, this shif+ was more than adequately compensated for by margins demonstrated in a previously submitted analysis. This event' is reportable pursuant-to Technical Specification 6.9.3.2.8.

I Item 27 A new ECCS analysis was performed in August, 1981, which showed that the new ECCS injection locations do not require any change to the reactor safety limits currently in use at knR2. It is, therefore, concluded that this error did not result in any potential. adverse impact to the public health r.nd safety.

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FOR LICENSEE EVENT REPORT'81-007, UPDATE. REPORT

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21. Cause Description 'and Analysis: On January 22, 1981, Westinghouse notified Carolina Power and Light about a potential modeling error in . the ECCS model used for LOCA analysis. The error was~ caused by an incorrect assumption of where Lthe low head: safety injection

. system discharges to the RCS. The model used at that' time. assumed injection directly into . the RCS cold leg. H. - B. Robinson Unit 2's low head rafety_ injection-is-actually into the accumulator 111nes which then -

inject into the RCS cold legs. H. B. Robinson Unit 2's fuel . vendor, Exxon, was ; informed of the assumed injection point and responded that'their model used values of pressure and flow that assumed direct-RCS cold : leg injection. . Exxon. then performed a preliminary reanalysis '

using the values of pressure and flow that correspond to low head safety injection into the accumulator legs. The results- were reported to Carolina Power and Light on February 12,.1981. These results showed an increase in peak clad temperature during' a LOCA. However,:

this increase is well within the margins available and ' demonstrated I

in previously submitted analyses. For this reason, it was concluded that this error would not result in any adverse impact to the public health and safety nor in any restriction to current plant operation and did not constitute an unreviewed safety question.

2. Corrective Action: Exxon performed a preliminary reanalysis of th'e LOCA event using the pressures ~ and flows that occur when low head safety injection is assumed to inject into the accumulator legs.

This reanalysis showed there was no safety concern.

3. Corrective ' Ac tion to Prevent Recurrence: Exxon completed a new

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ECCS analysis in August, 1981, which showed that the new'ECCS injection locations do not require any change to the reactor safety limits currently in use at HBR2. It is, therefore, concluded that this error did not result in any adverse impact to the public health and safety.

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