ML20236S587

Discusses Indications That Plant Licensed Using Siemens LOCA Methodology May Be Operating in Violation of 10CFR50.46

ML20236S587
Person / Time
Site:	Millstone
Issue date:	05/14/1998
From:	Maloney S AFFILIATION NOT ASSIGNED
To:	Collins T NRC (Affiliation Not Assigned)
References
DLNRC-9805-01-S, DLNRC-9805-1-S, NUDOCS 9807270076
Download: ML20236S587 (17)

Text

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c%.g C3/ED DEYONRUE N " l0 ? $ ' D }' } N R N eth Errter 3ggg DWRC M1/SM FUCL C CCCO' INT RO1 kt: 781740-1443 FAX: 7817401463 wehrt: wwwatww.mm Mr. Timothy E. Collins Office of Nuclear Reactor Regulations NRR/DSSMSRXB, Mail Stop OWFN/8E23 United States Nuclear Regulatory Commission Washington. Detrid of Columbia 20555 Subject Indicatens Plants Licensed Using Siemens LOCA Methodology May Be Operatili0 h Volation of10 CFR 50.46

Dear Mr. Collins:

Mr. Eugene imtro, NRC Deputy Dredor for ICAVP,9=0*=8M you mi ht have certam technimt 0

informaton relaisd to the May 12,1998 public meeting concoming Milstone Unt 2. Not knowing the proper protoccis for pursuin0 this information. I presentthis letter to you and ask you mule t to the appropriate indhdual If you are not that person.

Among otter thm0s, emergency core cookng systems (ECCS) are required to perform h such a manner that the manmum or peek fuel element cladding temperature (PCT) does not meeed 2200F. This limt is intended to prewnt fuel falute in a reador acedent. Changes or ermis affectino PCT calculations are reportable when decoered in an ew'uation model found acceptable to NRC. If the change or erroris sOnllicant, the heensee report must be fled within 30 days, and hciude a proposed schedule for teenalysis or other aden to comply wth NRC safety requirements in a reactor accdent.'

At the May 12,1998 public meeting conceming IWRistone Unt 2 ICAVP, Northeast UlHiss (NU) y reported the 8mmens methodologyis egeded to change due to ermes of an unspecWied nature. t was further reported, apparenty for some number of years, these ermts masked the correct PCT for a reactor accdent at plants licensed with Siemens' methodology - PCT in fact meseds NRC's 2200F safety limb. Notably, the higher PCT revelation is not unique to IWBlstone Unt 2; t apples to 11] plants licensed wilh the Semens methodology.a Since PCT wives abow 2200F Wlate Federal safety regulabons, and could senously enecerbate the public heellh consequences of a reactor accdent, this informaan is signi5 cant and demarx. Immedete aden to proled the public health and safety.

I NU also reported that Siemens fled a "Part 21," though the report was not ='=* ally idenblied ' In fact, Semens filed a Part 21 report on Febmary 23,1998 alerting the agency to mathematical armes in the RELAP4 model of large. break loss of coolant accdonts (LBLOCA). NU appeared to suggest Semens might haw been aware since at least March 1996 that these errors affect a sizeable porton of the US reador fleet.' Evidently under the NBistone Unt 2 ICAVP effort, Siemens has been wortung with NU staff to identify and corted errors in is reador acedent analysis methodology. Were t not for NU's ICAVP l

achwiles, t is conceiweble Siemens' errors would newr haw surfaced.

(

" Acceptance orserie for emergency core cooling systems f$r light meter nucieer peer reactors," 10 CFR 40.46 See Pese 5, Northeast utsese handout."Reenelysis Scope." statirig: "A Siernens metMdoingy chenee le Ikely..

• 3 See Pe08 t t. Northeast Utilities hondout. "Rennelyse scope," stating: " Generic issue sesociated unth vertebHy issues in the Siemens LBLOCA methodology."

• Notification or faiWe to comply or mestance of a detect and its evolustion,' 10 CFR 21.21

\\

see NRC Headquarters Deily Report. Fetwuery 23.1998 See Page 11, Northeast UtMiss handout.*Rennelysie scope," stseng: Reported under Part 21."

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E,.O & d, DLNRC 9805-01/SM, M

y 14,1998 E is commendable that Siemens has been both wiling and able to enter the industrfs " Holy of Hollies"-

PCT pmdidions in a reador accident-and flush out into the open longstanding errors. Apparenty, these errors are not restricted to ei:her PCT nor are they recent.

For emmple, Semens fled a Part 21 about a year ago reporting enors in accident modeling affecting "certain plants," which are not identified.' More recently, Siemens alerted the agency to significant nonconsenstisms affecting two US boihng water reactors.' With such a pattem of reports, there is often a tendency to shoot the messenger. Stdl, Siemens' willingness to adually follow the thread - and wth effed-speaks far louder than the industrys apparent service mark of"ct'mmtrnent to emellence."

At the same time, t is chiling to think so many years elapsed wth the PCT landmines in place.

Apparently, senous tedinical housecleaning only happens when a new vendor, forehn owned at that, wntures upon the scene, assumes " verbatim compliance" means just that, and kicks ('tnps?) owr a rock.

Millstone Unt 2's wlidation emerience also = =* what might adually be the rule in this industry, rather than the exeption. All told, not an especially inspiring image, by any stretch.

NRC scheduled a pubic meeting with Semens for May 21,1998 at which time addlionalinformation may become awlable. However, it was evident at the NU meetuig Siemens will not conect errors in ts PCT calculations and other studies unti mid-late June - 3 months or more svice Siemens first plumbed their depths. This schedule does not indude NU's review and wfidation efforts. Thus, t seems another

)

6-8 weeks must elapse before necessary changes to the Millstone Unt 2 operating license can even be identifed. This penod does not include NU's proposed modifications requiring NRC adion, time needed to determine the radiological consequences to the pubre, or time provided the public for comment about all of ths. Who knows what,if anything,is going on atthe operating readors.

For numerous reasons, but induding these PCT errors, Mitstone Unt 2 is shutdown. Errors in is operating fcense are of no immediate consequence to the public safety. That may be all the good news there is.

Unfortunately, plants fcensed to the Siemens methodology are cunently operating wthout ie=u uui.

When wilthey get around to comparable state of knowledge? Giwn the safety significance of tne PCT orror, Iis truly dichotomous that 10 CFR 50A6 only appres to a shutdown reactor-one that is apparently the sacrifcal lamb - Millstoria Unt 2.

For sudi stuatons, NRC's requirements for operating plants are a simple matter of law, and should leave no room for enforcementdiscretion:

propose immediate steps to demonstrate compliance or bring plant deshn or opnmtion into compliance with $50 A6 requirements."# (emphasis added)

The remedies for fcensees failing to comply wth safety requ'rements are equally clear, as at least Milstone Unt2 knowssowell:

"The Director of Nuclear Reactor Regulations may impose restrictions on roedor operation f it is found that the enluations of ECCS cooling performance submtted are not consistentwith pa'agraphs (a)(1)(i) and (iQ of this sedion.#

(emphasis added)

As they say, this seems like a "nMwainer." NRC need not look very far for guidanco on what must be done.

"Crectl Heat Fiux Database for 9x9 Fuel DeslGns ooes Not Mequatefy Estimate Uncesteintles," NRC Event I

May 22,1997

• Nonconsenettve Predctions or Monitored MCPR.* NRC Event 34119 Aprfl 21,1998 to CFR 50,46(a)(3)(f) 1o CFR So.4e(a)(2) 2

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.,._ a DLNRC 9805-01/SM, May 14,1998 So, what has been done? I confess that i don't haw a due, despie the fact t's not ewry day such a long L

and broad shadow is suddenly thrown across LOCA analyses.

The standard seems dear enough. Agencies regularly take prompt action to address uncertain circumstances potenhally affedag the public safety. For emmple, the potental for frayed Insulaten on electrical wires in Boeing 737s led to the removal of a major portion of that fleet fmm rewnue service unti sue time inspections resolwd their safety status if repairs are needed, the aircraft remains out of rewnue serWee unil completed. Such prompt adlon is entirely appropriate ghen the potental loss of life that could result from an accident triggered by an eledncal short.

As theysay, a "nMrsiner."

h the case of PCT temperatures, we may be dealing with a far more serious stustion than the potential for frayed wire leading to an electrical short on comrnercial aircraft and gntog abnormally hhh fuel wpors.

l Wth rising temperatures in a LOCA, well-estabished chemical and metallurgical ptr==== cause fuel rods to swell and owntually burst, spihng fisson produds into the coolant, out through the pipe break, and beyond. The dadding alloy rsects wth steam at accelerating rates as accdont temperatures rise.

l Abow 2200F, a postiw feedback loop dewlops-a "snowbaNing eflect'- in w&h smaN changes in nuclear fuel rod temperatures result in large changes in fuel damage and stil hhher fuel rod l

1 temperatures. The accdont at TMi 2 and fuel damage reseate demonstrates the time abow such

}

temperature limas need not be wry long before the deadly feedback loop is tri gered and senous core W

i damage results.

l We are not discusang the ethereal such as the safety significance of a leading" performance indsator, 4

or some PRA acenano penc5-whipped down to the 1xt 0 RY' threshold LOCA protodion is a mater of law. Licenses will no doubt be amended and plants modifed to reduce the PCT. This is real nuclear se There is also important precedentin the poices that ewiw if Federal LOCA requsements can be so l

casually wolated wthout swift, wry public, and the most serious agency adion, why should NRC enforce l

i BDy of the cummt portform of safety requirernents? If FAA can quicidy pull this naton's 737 fleet out of re enue service to insped wires susoeded of damage, NRC's course of adion should be no less clear for known def:.ds.

I in speelung wth W. Egan Wang yesterday, NRC's contad for the upcoming Semens meetog itwas otmous nether of us paacman a complete set of assental technical informaton w..wir,lig this potenbally senous policy and safetyissue. Therefore, I request ee following oformation at your eastest convenience, and as each piece bacomes swilable:

(1)

A Huting of au nudear factitles with a fcense amendment relying upon the Siamns' mmodology.

(2)

A copy of the Siemens' Part 21 report and other reports and consspondence fled by Siemens l

and licensees concemog the PCT enors and issues associated w2h ECCS performance.

(3)

Justification provded by NRC, Siemens, or the affeded licensees for continued power operatens while ECCS is inoperable for LOCA and other design basis accdents.

(4)

An aglanalen how the errors identified by S~emens could haw remained undiscowred in US readors allthessyears.

(5)

An men *** ment of thft Ikelhood that comparable ermrs east among other safety analyses, induding those of otherwndors.

I 3

• r%Y-14-1996 12:45

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(6)

What NRC intends to do to ensure the current Siemens PCT problem does not recur.

(7)

The acdons under 10 CFR 50.46 your sta# recommends, or your schedule for prosfing such recommendations, to the Director of Nuclear Reactor Regulations.

l Yea mbht also consder posting this information in a specal place on NRC's webste.

I apprecole your consideration of this matter. I realize ewn consdering my questions dierts you from presang and important safety duties, and I apologir.e for any inconwnience.

As a matter of courtesy, I am provding a copy of th' letterto Mr. Eugene Imbro, NRC's senior s

representatne at the May 12,1998 NU meeting Mr. Imbro was wry graccus in answering my questions, despRe his rather ti0ht trawl plans that day.

Gien Dr. Jacimon's special interest in NU's desbn basis widation efforts and their lessons for nuclear safety, I am also forwarding a copy to her office.

Sin i

PHEN MALON i

Endosure Northeast UtRRies Handout Heanalysis scope." presented at Millstone Unit 2 ICAVP Pubib. 'n v, Northeast Utailies Corporate Offices, Berlin Conneebcut, May 12,1998 l

Cc:

r. Shirley Jackson, Chairman, US Nudear Regulatory Commission, w/ enclosure Mr. Eugene V. Imbro, US Nuclear Regulatory Commission, w/ enclosure Via:

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MILLSTONE UNIT 2

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REANALYSIS SCOPE - DOSE ANALYSIS ACCIDENT IN FSAR NOW

{

1. LOSS OF COOLANT ACCIDENT l

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a. OFF SITE YES l

b. MP2 CONTROL ROOM YES i

c. MP3 LOCA TO MP2 CONTROL ROOM YES j

2. MAIN STEAM LINE BREAK NO

3. STEAM GENERATOR TUBE RUPTURE YES

4. ROD EJECTION ACCIDENT NO

5. FUEL HANDLING ACCIDENT YES

6. CASriDROP YES Status for the above reanalysis: Input parameters are being finalized to allow Stone and Webster to begin analysis.

Best estimate schedule: July 31.1998 i

E-T TAL P.18