ML19322A439

RO 77-04/1P:on 770415,nonconservative Error Found in Safety Analysis to Support Increase in Pressurizer Code Safety Valve Setpoint to 2500 Psig.Caused by Erroneous Assumptions Made for Total Combined Relief Valve Capacity

ML19322A439
Person / Time
Site:	Three Mile Island
Issue date:	04/18/1977
From:	Colitz J METROPOLITAN EDISON CO.
To:
References
NUDOCS 7910250555
Download: ML19322A439 (2)

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"'r. J. P. O' Pc i11y Diract6 rate of Degulatory Operatio,5 Pe; ion I f;sticar Regulatory Co,-ission 631 Park Avenue V,in; of Prussia, Penna, 19t05 Operatin: License DPR-59 Docket 59-2B?

Subject:

Reportable Occurrence No. 77-04/V

Dear "r. O'Peilly:

This teleare- is to cnnfirr the conversation beteen Mr. A. ?;. Tasano

( D.c : f o > I-?.0- ) m d t'r. J. P. O'Hanlon (Ttt!-I Unit Superintendent of Tesnical Svopert) at 1833 hoars on 15 Anril 1977.

inis rea?rt 4s sub-itted in accordance with Paragraph 6.C.2. A(8).

This event is considered reportable in that a nonconservatIve error w:s discovered in the safety analysis which was done to sup; ort increasir.;

th? Pressurizer Code Safety Valve setcoint to 250? psig (+ 1'.). This error co.;1d h?ve la.1 to oparating pressures daring accidant coniitions which

< sid tsve bear. 0.3 psic above the pre.icisly ar.a?yzc:' res>1t of 273? psig

5. still b?lo.: tre Entter Co31 ant Syste- Wety IMt o' 2759 psic. inis cerer w?s ditrovarei daring en uM? tin; cf tre velves' na-splate data s' en th? vr" ?r certi'ied velve cap,acity wn foJrd to be acr.erce.tly less than in. t rc tired by the safety analysis. Tr.e inve tication and re.*nalysis Pich folioed this discovery deten-ined th:t the total cr.-5ined relief c m city of te* to (2) valves was ceroecoasty ess.r-ed.to be 619,203 lb/hr at a st.:" pressure three (3c) percent r$we the 2507 psio setp7 int. A total crinM relief cer:tity of 551,0?? lb/nr at a ste.* pressure these (3")

pe r e c*. above the 2592 psic setoaint is r.,re recrosentative cf the ectuti safety valve capacity. It is this corre: tion of the total ccr-5fr.ed relief 7910250 f%

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car ec- ty ti- 561,&;0 l'./rr e.ich yields !*e C.~t is releth f i y Eecwie the r.?: nit

• of this tor. ceserynive erree re-imi nifice .t anj the r Min to the si ety li-it is r.rt st;nific.ir.tly f

55 f ety d;;e', it is believed that no siorifice .t h27 erd to th

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The code safety valves w.ill be testad to verify the these cedith .s. ,

i 2500 psi; setN nt ard a Technical Spo:ification Very truly y:;rs. l 9'9GO' d.J.Coli Unit I Superinterdent Tnrce F*!1e Islee.d !.aclear Static' J.'C/pa s -

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