ML20092H259

Submits List of Requested Info Re Insps Performed on Various Core Components Susceptible to Age Cracking & Requests Comment on Advisability & Need for mid-cycle Insps on Vermont Yankee Core Shroud

ML20092H259
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	07/17/1995
From:	Sherman W VERMONT, STATE OF
To:	Chawaga D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20092H224	List: ML20092H259
References
NUDOCS 9509200330
Download: ML20092H259 (14)

Text

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mm frATE OF VERBeOffr DEFARTMENF or MMJC SERVICE l

130 STATE STRWT l

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maly 17, 1995 -

J Mr. David Chewage, State Programs U.S. Nuclear Regulatory Commission -- Region ~I 475 Allendale Road i

King of Prussia, PA 19406 Dear Mr. chavagas

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In this letter, we request information regarding inspections performed on various core components which are susceptible to age i

oracking.

We also ask your comment on the avisabili;;y and need i

for' aid-cycle inspections of the Vermont Yankee Core Shroud.

i For our Vermont state Nuclear Advisory Panel meeting of'May 23, 1995, we received the attached letters from Michael'J. Daley 1

and the Citizen Awareness Network on the subject of the adequacy of reactor internals components.

The letters identify core i

components which are susceptible to age cracking, and continue to i

request a mid-cycle inspection of these components and an NRC l

public meeting.

l In order to assist us with our considerations, ne request the followingt

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1. The regulatory requirement for inspections for the core components identified as age oracking' susceptible ~in either j

NUREG/CR-5754 or the list of Oyster Creek items provided by

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2. The.safahr i = * =*ia==

for cracking in the core ocuponents identified as ag6^gracking susceptible in either NUA3G/CR-l 5754 or the list'of oyster Creek items provided by NIRS.

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3. A opunent on whether more accurate inspection methods are available than those which Vermont Yankee uses for these inspections, and the advisability of using inore accurate techniques.

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4. A comment of the indvisability and need for a mid-cycle inspection of the Vermont Yankee core shroud.

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9509200330 950919 i

PDR ADOCK 05000271 G

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We would appreciate any other information you could provide to assist our consideration of this issue.

We plan to take up this issue in a Panel meeting this Fall and hope that.NRC will be able send a recrementative to particinate..

sincerely, W 1 iam

. Sherman Far the Panel O

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.2 kt e..e-j' Michael J. Daley rd ? ' '.

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RFD/J. Sam 627 Purwy, Vermone 053M a m..

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May 19, 1993

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Dear Members of V5 NAP:

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. I regret that I cannot be present at, your meeting. on May 23.

I will be close by, however, educating the public about the safe, clean alternatives to Vermont Yankee at the j

7th Annual Tour De Sol solar and electric car race.

l Perhaps you can stop by the Bractieboro High School after your meet-ing.

j Governor Dean will be on hand to drive Vermont's entry across the finish line.

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I as writing to share my concern that Vermont Yankee.

j officists (with NRC's' blessing) have prematurely screwed the cap back on their reactor.

Some members may recall meeting, in Spring 1992, wi'th nuclear safety expert Robert Pollard of the Union.of Con-

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I corned Scientists.

At that meeting, he told the Panel that degradation of safety components due to aging is one of most

• 1 significant safety issues confronting the nuclear industry.

I believe the Panel has come to share an interest in this-1 subj ect.

l In recent conversations with NECNP Trustee Diana l,

Sidebotham, Mr. Pollard indicated that core shroud cracking l

'is the tip of the iceberg where age-related degradation is concerned.

The stainless steel alloy used in the shroud is particularly susceptible to intergranular stress corrosion cracking (ISCC).

(Note: VY had to repisce the entire main coolant loop piping in the mid-1980s due to ISCC.)

This same alloy is used in numerous other reactor in-1 tornals, many with safety related functions.

A report i

prepared by the Nuclear Information and Referral Service l

(NIRS, a Washington, DC-based industry watchdog) identified over 25 areas of concern at the Oyster Creek reactor (also a i

BWR and this report is enclosed for your information).

i To the best of my understanding, upon identifying the core i

shroud cracke using an advanced ultrasound technique. Ver-mont Yankee did not expand the inspection to include other susceptible components.

(These will not necessarily be the i

same as those at Oyster Creek.

Vermont Yankee should supply panel--and.the public--with an inventory of all components containing alloys similar to the core shroud.)

Vermont Yankee's failure to extend their inspection is particu1&rly disturbing given the historic inability of pre-vious (now outmoded) inspection methods to identify crack-ing.

For example, before applying advanced technology to the inspection of steam generator tubes, the Maine Yankee plant had identified about 500 flawed tubes out of 17,000 total.'

Advanced inspection methods have today identified fisws in more than half of the tubes -- over 8.000.

In the

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i words of NRCNF President and Maine resident, Jim Ferkins.

"the old method missed virtually all of the problem"..-.

The situation is similar at Vermont Yankee..

During the Fall 1993 outage, Vermont Yankee made a visual inspection of the shroud with a 1 millimeter resolution video camera.

i This method revealed no cracking.

When ultra sound techni-ques were applied in this outage, cracks were " discovered",.

4 one penetrating half way through the. shroud, i

This raises.some troubling issues:

1 Were there no cracks in 19931 If so, these current f

ones must have appeared in just one operating cycle.

When i

in the cycle did they develop?

Or were the cracks present, but missed?

If so, how can any assursace be given that safety related components using i

similar alloys are crack free?

j Further, without accurate' records of when cracks first appeared (and their actual growth rates over time), how can l

Vermont Ya'nkee determine a. reference point to use in cal-i culating growth rates?

I hope some answers will emerge from your meeting with Vermont Yankee officials.

I as indebted to the Citisen Awareness Network (CAN) for bringing much of this information to my attention.

They have been in constant communication with the NRC since the cracks were discovered.

The accompanying letter from CAN j

Fresident Debby Kats more fully outlines their concerns, I

which we share.

l The New sngland Coalition and citizen Awareness Network I

intend to ask the NRC to_ require a mid-eyela inanneelan of l

the core shroud and related mafa*y ea-aonents.

This would j

oe rotAowea or an NRC public hearing to explain the results to the public before the plant restarted.

j Though 7 must miss your meeting. I as happy to report i

that Diana Sidebothan will be present for the Coalition, and Debby Kats will be.present for CAN.

They will be able to elaborate on the concerns I have shared here.

Complam uncertainties are involved when materials are subjected to the harsh nuclear environment' that make i

predication difficult.

In such situations, the Yankee Rowe and Maine Yankee experiences have clearly demonstrated that j

public health and safety is best assured by stopping to take a look at real cracks rather than relying on, computer model-l ing.

j Af ter your consideration of this issue, I hope you will l

Join us in calling for a mid-cycle inspection and hearing.

j I look forward to the results of your deliberations.

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CITIZEN AWARENESS NETWORK a

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May23,1995

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l Dest Members of Vanxmt State Nuclear Advisory PaswL i

Citisses Awarenses Network is here to express our concem about du Shroud Inspe

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Flaw Evaluation ofthe Vamont Yankee Nuclear Power Station. During the recent re i

outage. Vermont Yankee idaitified cracking in the cinumferennial welds in the core shroud.

There was intergrounular stress corrosion cracking ( ISCC) in all welds except for H7. The crackhts in Weld # H5 was mer l'in depdt. The shroud is 2* thick end. fourteen feet h 1

This creding information was ascatained through ultrasonic testing. The VY shroud was fabricated using high carbon inconnel 304 stainless steel, and has been found at other re to be susceptible to ISCC. This cracking is ofconcern to citizeus living in proximity to t reactor because other safety related components are fabricated from this material 1

In " Boiling Water Ranctor Intemals Aging Degradation Study", NUREO)CR-5754, issued September 1993, major aging mechanisas where identifled that are limiting the fhactional lifs

expectancy ofsafety-related components in BWRs. The report haunts the potential effects of aging on 25 BWR intamal components. Components fabricated from cast anatenitle i

stainless steel (Type 304 widely used in tlw industry anxi at Vennont Yankee) are by prolonged exposure to high temperature. conusive water chemistry, neutron bomb i

and fatigue resulting in stress cormsion eracking. Neither the industry nor the NRC are able fully understand dw growth rate nwchanism of cracks ami the suh-M rate of deterioration of the systens.

Notwithstandes this, the NRC has panted the licenses permission to operate until ths next refiniing which is scheduled for September.19%,18 months Dom now. The reactor was abis i

to demonstrale that there is sufBcient structural liganant tojustify one additional cycle of operation. At that time the resenor will be required to reinspect and/or repair the shroud. The i

corrosive cracking of th's core shroud is in fact a bell weather for the potential embrittlement and subsequent thuure of these other components. Many of these compensuls are safet j

related.

These "omponents include:

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s Cott Spesy Sparger which ispects cooling water into the core in the event of a loss of j

coolant accessat to prewnt the fuel cladding from melting. Cracks in the CSS can

• potentially sher the Dow of coolant to the core and might lead to the generation ofloose parts in the reactor pressure vessel".(NRC)

Core Spray Anansius Piping. safety related. tids is a component of tlw Core Spray System 6

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which supplies cooling water to mactor fuel assemblies durbg a loss of Coolant Accident.

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.. Feedunter Sparger, safety esisted, providas =43 "g homogmous and unifbsm j

i maintain adequate reactor water lewi into the core.semiparature i

,e c Top Cadde, safety estated, prmides ' lateral support to the reactor core a maintains proper spacing ofthe upper ends ofthe ibei====M=

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Core Plade, safety related prmides structural support to the reactair core the! ~hi

. Centrei Rod Guide Tubes, safety.celated prwides laters! guidance to a control red and vertical support for the four Aiel amernbiles surrounding the control rod.

Control Rod Drive Ilousing/ Stub Tube, safety related internal component provi i

access into the icactor pressure vessel for control rod drin inachanism.

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. Shroud Support and Access lloie Covers, safety-related. kumut shmud baffle plat y

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carries the weight of tlw shroud. sisuud lwad. steam seperators, peripheral (bel assem corv plate, and top guide.

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CAN has been unable to ansertain whether any taalne orinanections haw heen aconnmiinhe In reference to the ISCC phenomena outside of Ws ten year inspection cycle program on thsee eenyonents. NRC Projoet h! anger Dorman stated that them components had not bee i

cheeked at this refkaling. NRC Resident inspector Eichenholtz was unable to give an j

of taw wn your pian. We believe these s31 items merit increased attation given the corrosin j

eracking ofthe shroud.

.\\t hiaine Yankee M0 cracks were imlicated ht tutwo in Llwateam Generators.

the uw of the plus pohn probe a more sensitive instninwnt. half of the tuhen (8.000) were j

round to be llawed. 7.elee. the maker of tlw plus point probe has developed the super pr which is used in PWRa. Could this s3inent he used in BWR's such a VY to identify cra t

f We am tlwmfore asking,wur panel to support:

i A request that tim NRC prmide tlw data to demonstrate catainty that the geomth rate in l

the deterioration of the shmud and the 25 component s>wems wift not proceed to failure before the twst refueling outage.

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. A mid lbeling inspection to examine these 25 component s3sams and the shtoud M l

A Hearing with the Nuclear Regulatory Commission in nu,ndmace to explain to the community in Vermain and hiessachusetta the problens with Core Shroud Conesion

• Cracking and the 25 component systems before the next redheling cywle in ottier to clar and demonstrate a review of the safety issues arising frerin the erscked duoud.

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(noen NRC Ir@ Report, Memo la file, Dated 950128; a takso Som Telcon USNRC sWe#Uhl! n l l

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NIRScomments ha.n been incorpurutedin trallcs.

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COMPMENT,.

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• I COR3 $ PRAY SPARGER

(" Previous Experience laserstamalar Suess Cor:odon --

Creaking [lOSCCJ" TK")

-Made gf1)pe 304 stainiss: steel'

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.Sqferivelated beternal,

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-Two cirsular headers at diferent elevations with two tu boxpipe sect luns which infect coolhtg unter into the cars in the event ofa Loss ofCoolant Accident to pnwnt thd)ltel#1~GL fem g

meltinlg.

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-Accordng to a GPUNpecial report to NBC (No v. J.199e) presenting results v/insp6ctions of

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the core spesp sporgerfor the C)<le 13 refueling outage, the " Previous expertenoe* oferacMng ofthe Oystar Creek care.sprqv sparger wasflest identifiedin 1978 as "one through w$l'i: rack" in core spray sparger with air release obserwdfrom a single 208 degree crack. The hport documents 28 additionally cracks idetwffled in the core spray sparger 1980, and 3 Identf6d in i

i 1982, Repair brackets were Installed l

-Cracks in the c'are spm spargers can potentially alter theflow ofevolant lo the core,and might lead to the seneration ofl&ose parts in'the reactor pressure vessel.

l NRCirformation Notice 80-14 (Ref 4). addrusus problems and outlines inspection l

requirements.

l CORE SPRAY ANNULUS PIPING

( Weld Blowout Hole" " Acceptable As If) l Made of1)pe 304 stainlessstui.

l Safety.relatedInternal 1

The core spm amagus or core spray line internalpiping is a cenponent ofthe core spntv i

system which supplies coolkes water to the reactorfuel assemblies during a Lass ofCoolant Accident toprewntjhe)kel claddingkom melting. The core spesy line cornects the extemi

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core spt17p(paing to the core spray spargers.

-Axording to OPUNspulal report to NRC (Nov. J. I994) presenting the results ofkupections Afthe care spray annsdus pipingfor the Cycle 13 rqfueling outage. :he,"Previour erpedance" ofcracking ofthe spray line piping wasflest obsernd in 1980 as "rwo indaations." The report documentsan additional 3 Indications ("one through weld hole"and "2.llnear") wre ident{ fled in I992 where " Air releasefrom Wald L 3A is continuous.*

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STEAM SEPARATOR

(" Bracket Crack" " Accepted As fr)

.Made ofType 304 slainless steel

-Srporates water dropletsfom,tteam generated in the core j

-l29 star yyes, also 7)po 304, welded to openings in Ihe shroud head

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i j 8 TEAM DRYER

("Dtyer BrackW Cnscidsg" "5Wp Drlund Fatigue")

.Mede 41)pe 304steln!*psteel i

Removes arcast moistww in steen alting the arenait separators Darlag the R13 outege a ennek uneident$ed in the steans kyer bracket. As a r j

redferiert emissions)hnn Ik component G rena/hr), GPUN undertook an sederwater and

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mitigation dort in the equipmentstorage pool byplasma initirng 1/2 inch holas at eaa j

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1 SHROUD. HEAD BOLTS

(" Previous Experience Replaced Duets IOSCC" "OK")

1 Made ofInconnel 600 alloy, alsa suscepttble to IGSCC.

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< Fastens shroudheadto core shroudtopfiange.

l ORE SUPPORT PLATE HOLD DOWN BOLTS

("OK")

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m l 1 RACKETS for:

("BentIToer" "OK As Is")

QUIDE BOLTS SPECDdEN HOLDER I EEDWATER SPARGER

' Keeper Bolt Tack Weld Crack" "OK As Is")

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Mode oflype JJ6L and JJdhD stainless slet1.

-Safety relatedreactor Internal component.

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Uteder normal operation.feedwater spargerprovides subecoling, hamngannus and un(form

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innperatwe mittre to helpprevent as>wsmet.~lcalpner distribution in the oors. Dwing e i

LOC 4 Ihefeeheter spa ger becomes part ofthe HIgh.Prassure Coolant 1rg(ectton (HPCI)

Spetem to maintain on adequate reactor water levelinto the core.

-GPUN identifled a crack in the keeper bolt on thefeedwoter sparger during RIS.11re crack was

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tack welded..

During I972. large circungferentual crackt were detecte.dIts afeedwater sparger in otherBWRs

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and wrw attributed taflow inherd vibrations.

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l )P GUIDE

("Three Cracks Midspan" "OK As is"

"'three Previous cracks No Measurable Crowth) l l

eMade of Cpe 304 stainless sten!

.Sqfery relatelcompwwnr

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.Provides lateral sspport to the reactorfuel core assembly and maintains proper spacing ofthe l

ypper ends ofthefuelassembilts.

.in a report to NRC. General Public Utility Nuclear 'dentyled structural cracking q(the top guide in August i991. However. NRC oficials responsiblefor the materials analysis and l

evoluutton of0,wter Creek reactor Internnnis claimed.'o only recently have been aunent <the l

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General Electric issueda service ofert (AlCS(L 071 Water Reactor opetutors to inspect top guida andcore platesfor crac l

crachkng was noted on then componesus in the Waergaaen BWR in Germ The dettwe ofInspmsion ofthe top p4tu is in pestion. NIBSbeltav

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ring was intpected while a lattice ofintersecting steel beams widad tog

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rim me not han been ingpected Each spare openisofarmed& the noteesenths l

gwGdei lateml aspport ared nanintatnaproper spectagfor}lntr)Let apsemblies.

j JN-CORE NEUTRON FLUX MONTTOM 110UMJtvGt INTERMEDIATE RANGE MONITOR /

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SOURCE RANGR MONITOR /

LOCAL POWER RANGE MONITOR

("IGSCC Crackha.ReplaceableComponent").

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-The haueings ars made of1)pe 304 stainless steel.

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-The incore neutron)!ur monitor housing providn a perwaration path for innetton qfmon i

into the reactorpressure vessel.

CORE SHROUD

("Significant Cracking in H4 Welda "Permdnent RapairInstalled")

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The shendis a 24gmentedcfindrical. steel 3tructure made ofType J04 stalklus steelmed weldedtogether.

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safety relatedintnrnalcomponent Provtdu lateral merwint to the reactor core, provides a refloodable compartment in the event

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of a Lou OfCcolont Accident, andprovides)6r coolant waterflow to the core. Because the shroud connects to the core plate at the bottom ofthe reactor core assembly with the top g plate at the top ofthe reactor core anembly, any lateralship resulting) tom a through wil break of,a circumferential wid of the shroud outside ofa tolerance ofone eighth ofan inch

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' neuldprennt thefullintenton ofthe controlrodt.

-Extensive crackng was Jdent@ed on'the He mid, approximately the midrifofthe shroud, Canteury to Industry asyurreanen to data, most shroud ernektag has been notedat the 4perand lowrlevel wids ofthe shroud

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-GPUN completed a *permement repolt' utilising 10 tid rods attachid to t,he top and bottom of the core shroudintembly to prevent lateral motion.. (Note: bottom portion qfthe 'Jtx* ts hooked into plasma are cut holes in plotu Af Type 304 welded to the shroud as part qftbe i

original dulgn. Vadnerable to ICSCC]

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-The Bolling Water Reoctor Owners Group has ident@ed that crackktg on the core shrowiis an Indicator ofcrocking that could be occurring to other safety related reactor Internels.

-One ofthe original reactors to show signs ofshroud cracking, the Wuerganen BWR. Germany, was not allowed by the Germon nticlear regulator to install a 'flx*. Instood Wuergassen has undenaken to commence a two year outage und replacement afshe shroud at an uttmated cust ofas much as $65 million.

SHROUD BRACKETS

(" Minor Indication in Shroud To Btsekat Weld" "OK")

. Oyster Creekis the onlyplaru that has shroud brackets.

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. Wuasassen has sondertakun to commenca a tw w couwe shmsadat an estinsatedcart das much as S63 aullon.

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PARTE NOT MntfATRn Mt INADFfTRn deias the R15 outans thomsk idend#ed a i

selbey.: dated componenes and vulnerable to Senes conosion Crackies (3CC) la " Boning. Water l

Ranctorlaternals Aglag Degradstion Study'(NUR$G/CR-$754), psupered ihr NRC by Ook Ridge i

Nselonel 1.aberstory, seposeber,1993 and soning waar xenator ownsa onnep Messin8 whh NR.C, i

June 2s,1994. These components are subject to mguistions umkr American Society ofMechanical nas e sou ams re v

uAsus sarv) cod., Appendix 1 s.cii ni, s

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CORE PLATE I

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Maait of1)pr SN nainlen steel.

i Wtatedinterrurt component

-Locatedat the bottom ofthe reactor care anembly the core plateprovides structwolsspport to I

the reactor corefuel annablies andper/prations in theplate provide guidance to contralrod l

Sulde tubes

-4 GE servlet alert (RICSIL 071) odvindBWR operators to innpect the coreplate gter seeing j

extensin cracking qfthe coreplate at Wuergesun, Germerp l

-0) uter Creekpassedour this inspection because the conponent sus " inaccessible."

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CONTROL ROD GUIDE TUBES Made of1)pe 3N.stainleasteel i

.Sghty relatedcomponent l

Ptsvides lateral guidance to a control rod and nrtical supportfor the fourfuel assembitae surroundtong that control rod. Errands sqrfem the coneelrod drin housing and through the -

l holula the coreplate.

l CONTROLROD DRIVEHOUSING/STUBTUBE.

-Made qf1)pe 304staintaasteel l

.Se)lrry related internal congponent

.Provides geess into the reactorpresswe nsselJbr conavlrod kin mechanism.

-Stub tubes are port ofthe readerpressure usal on older model BWRs.

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Leakage.has been detected in the gpp betwen the reactorpressure nuel andthe ControlRod Drive Ifouting in other BWR s.

CONTI4.0L BLADE

-Mode oft >pe JN staintensteel l

-Providesfor reector core reactivity control l' -.-

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'PhPsMet assement sagyart so de sveau gonwors h arAsm M surarusse y(decorwsArossi i

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SEROUDSUPPORT AND ACCESSHOIRCOVER$

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-the noenne hele eenr Is aande 44001400 (saeaptiblelo AnsCQ.

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yehantial.wy.ne,v 4nr shrossfmpport also kaans er the shromf bgpeplate, corries the wight (ths W. thremi head, steam aparators. perwheral. thel assenbita. ooreplate, arut top Swide.

itproddes lateselsspport to chefuelasumbilu A====*'~pl~ra watA & A--

se 'm ihn'.w are**&==:and the Inner adww.u-ak one =a w

.The Accars Holo Cones or mamp cours are cVcularateelplater wMeh areped Ireo.

i run accen holds,1A0 degreu apart, hatuwen riu usant mR andthe shromi l

-1nrough-wall-cracking in thi nidafths accen hole cowr canjeopardtu v4toodabury 1

ofthe cars by creating an alternarepowpath to bypaa the core daring nornaal and

.aocident co4tions. fiaHure'ofthe acswa h6te baHr willto nWshromisapport asiet' l

. otskit lot a scured hole cover' being swpt ay byfawpad inne the realhadationpung l

suotton line, eauntow danmass to the punp.

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.ORFICED FUEL SUPPORT (OFS)FIECE

-b standant OFBplace is castfvm Grade CF-3 or CF-4 steel. W peripheral 0$8 is I

made ofType 304staintenstui.

-Provides lateral ssepart madclintunent to thefuti assemblies at wil'as distributiets l

cooling water so thars throsqh an or$ce. The neight efthefuel assembliu it i

trang/hrred to t'n cortrol reddrin tubes through the OF5 piece.

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i Mr. David Chawage, State Proctrmas m

U.S. Nuclear Regulatory cosa;.ssion -- Region'I 475 Allendale Road l

King of Prussia, PA 19406'

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1 Dear Mr. chawagas i

.l In this lettier, we request information regarding-inspectiege performed on various core components which are susceptible to age

cracking, we also ask your consent on the avisability and need i

for' aid-cycle inspections of the Vermont Yankee Core Shroud.

For our Vermont state Nuclear Advisory Panel meeting of May j

23, 1995, we received the attached letters from Michael 7." Daley i

and the citizen Awareness Network on the subject of the' adequacy 1

of reactor internals components.

The letters identify core components which are susceptible to age cracking, and continue to l

request a mid-cycle inspection of these components and an NRC public meeting.

In order to assist us with our considerations, i request the following

}

1. The regulatory requirement for inspect. ions for the core components identified as age oracking susceptible in either NUREG/CR-5754 or the list of oyster Creek i w provided by l

' NIRS.

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2. The saimer ima14a=+iana for cracking in the core ocuponents identified as agF eracking susceptible in either NOR30/CR-5754 or the list'of Oyster Creek items provided by NZ38.

2

3. A cpammat on whether more accurate inspection methods are available than those which Vermont Yankee uses for these inspections, and the advisability of using inore accurate techniques.

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4. A comment of the indvisability and need for a mid-cycle 1

inspection of the Vermont Yankee core shroud.

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We would appreciate any other information you could provide to assist our consideration of this issue.

We plan to take up i

i this issue in a Panel meeting this Fall and hope.that,.lGtC will be able send a representative to particioate..-

l sincerely, i

i.

I w 1 iam

. Sherman 1

Far the Panel d

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<am m.uos M,aM3 2 u Hl w.

l May 19, 1998 m.

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Dear Members of VSNAP:

,.,,,, g,

o a.rt i r I regret that I cannot be present-at-your meeting on. - -

3 May 23.

I will be close by, however, educating the public about the safe, clean alternatives to Vermont Yankee at the

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7th Annual Tour De Sol solar and electric car race.

Perhapa you can stop by the Brattleboro High School after your meet-i ing.

Governor Dean vill be on hand to drive Vermont's entry

}

across the finish line.

I as writing'to share my concern that Vermont Yankee officists (with NRC's blessing) have prematurely screwed the

,~

cap back on'their reactor.

i Some members may recall meetiac, in Spring.1992,. wi'th

'1 i

nuclear safety expert Robert Pollard of the Union-of Con ~.

e corned Scientists.

At that meeting, he told the Panel that degradation of safety components due to aging is one of most i

significant safety issues confronting the nuclear industry.

i I believe the Panel has come to share an interest in this j

subj er:t.

In recent conversations wit.h NECNP Trustee Diana i

Sidebotham, Mr. Pollard indicated that core shroud' cracking i

'is the tip of the iceberg where age-related degradation is j

concerned.

The stainless steel alloy used in the shroud is particularly w eeptible to intergranular stress corrosion i

cracking (ISCC).

(Note: VY had to replace the entire main coolant loop piping in the mid-1980s due to ISCC.)

l This same alloy is used in numerous other react gr in-tornals, many with safety related functions.

A report prepared by the Nuclear Information and Referral Service (NIRS, a Washington. DC' based industry watchdog) identified over 25 areas of concern at the Oyster Creek reactor (also a BWR and this report is enclosed for your information).

To the best of my understanding, upon identifying the ccre shroud cracks using an advanced ultrasound technique, Ver-mont Yankee did not expand'the inspection to include other susceptible components.

(These will not necessarily be the same as those at Oyster Creek.

Vermont Yankee should supply panel--and,the public--with an inventory of all components containing alloys similar to the core shroud.)

Vermont Yankee's failure to extend their inspection is particulhrly disturbing given the historic inability of pre-vtous (now outmoded) inspection methods to identify crack-ing.

For example, before applying advanced technology to the inspection of ateam generator tubes, the Maine Yankee plant had identified about 500 flawed tubes out of 17,000 total.'

Advanced inspectio'n methods have today identified fisws in more than half of the tubes -- over 8,000.

In the

. sw.:

words of NgCNF President and Maine resident, Jim Perkins, "the old method missed virtually all of the probles".

The situation is similar at Vermont Yankee..

During the Fall 1998 ostage, Vermont Yankee made a visual inspection of the shroud with a 1 millimeter resolution video camera.

This method revealed no cracking.

When ultra sound techni-ques were applied in this outage, cracks were " discovered",

one penetrating half way through the. shroud.

This raises some troubling issues:

Were there no cracks in 19937 If so, these current' ones must have appeared in just one operating cycle.

When in the cycle did they develop?

Or were the cracks present, but missed?

If so, how can any assurunce be'given that safety reisted components using similar alloys are crack free?

Further, without accurate records of when cracks first appeared (and their actual growth rates over time), how can.

Vermont Ya'nkee determine a reference point to use in cal-culating growth rates?

I hope some answers will emerge from your meeting with vermont Yankee officials.

I as indebted to the citizen Awareness Network (CAN) for bringing much of this information to my attention.

They have been in constant coensunication with the NRC since the cracks were discovered.

The accompanying letter from CAN j

President Debby Kats more fully outlines their concerns, which we share.

)

The New England Coalition and citizen Awarenese Network i

intend to ask th e NRC to__ require a amid-.eyeta inanmeelan of j

the core shroud and related =mfa*y ea-aonents.

This would ce rouoven oy en nac public hearing to explain the results to the public before the plant restarted.

l Though 7 must sids your meeting, I am happy to report that Diana Sidebothan will be present for the Coalition, and Debby Katz vill be,present for CAN.

They will be able to elaborate on the concerns I have shared here.

Complen uncertainties are involved when esterials are subjected to the harsh nuclear environment that make predication difficult.

In such situations, the Yankee Rowe i

and Maine Yankee amperiences have clearly demonstrated that public health and safety is best assured by stopping to take a look at real cracks rather than relying on, computer model-ing.

After your consideration of this issue, I hope you will join us in calling for a mid-cycle inspection and hearing.

I look forward to the results of your deliberations.

i Sinc r e

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May 23,1995

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j Deer Members of Veramit State Nuclear Advisory Panel I

Citizans Awareness Network is here to expresa our concem about the Shroud I Flaw Evaluation ofthe Vennoot Yankee Nuclear Power Station. During the rec outage. Vermont Yankee idaitified cracking in the circumferential welds in the core shroud There was intergrounular struss corrosiou cr=Aing( ISCC)in all welds except for H7. %

1 cracknig in Weld # H5 was over l'in depth. The shroud is 2* thick and. fourteen f nis craddag information was ascertained through ultrasonic testing ne VY shroud was i

fabricated using high carbon Inconnel 304 stainless steel, and has been found at j

to be susceptible to ISCC. His cracking is of concem to citizous living in proximity j

reactor W-other safety related components are fbbricated from this material.

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In " Boiling Water Ranctor hiernals Aging Degradation Study", NUREG)CR-5754, issu i

j September 1993, major aging rn~4=aians where identified that are ihniting the fhoctiona j

expectancy ofsafety.cetated components in BWRs. De report 4-=are the potential effects ofaging on 25 BWR h emal components. Components fabricated from cast austenitic stainless steel (Type 304 widely used in the hulustry and at Vermont Yankee)

I by prolonged exposure to high temperature. conusive water chemistry, neutron b and fatigue resuhing ht stnas corrosion eracking. Neither the ' dustry nor tlw NRC are ab e

fully understand tlw growth rate mechanism of cracks ami the subsequent rate ofd:tcie j

of the systens.

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Notwithstamiing this, the NRC has granted the licenses pennission to operate until the nest refueling which is schedated for September.1996.13 months Dom now. The reacter was ab to demonstrase that there is suf5cient sansctural lissment tojustify one additional cycle o operation. At that time the rencear will be required to reinspect and/or repair the shroud. The corrosive cradting of this core shroud is in fact a bell weather for the potential embriulemsat and subesquent ikilure of these other components. Many of these componnats are sa related.

i These componentsinAmie:

i Corv 8 prey Sparser. which injects cooling water into the core in the event of a loss of coolant accident to prevent tlw fuel cladding from meking, Cracks in the CSS can "potentially aberthe Gow of coolant to the core and might Iced to the smaration ofloans parts in the reactor pressure vessc!".(NRC)

Cose Spray Annubes Piping, safety related. this is a component ofthe Core Spray System 4

which supplies cooling water to reactor tial assemblies durbig a loss of Coolant Accident.

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.. Feedusr Sparger, safetyeissed providas subcooling, F ; -- -- and unifbre l

snaintain adequate reactor %Wer lewi into die core.tamparatum n*

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Top Cuide, safetymisted;provides laseral support to ths reactor core assembl higs proper spacing of the upper ends ofthe thei assemblies.,.

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Core plate, safety missed presides structural support to du genced core ~fbeIMin

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. Centeel Rod Guide Tubes, safety-related provides lateral guidance to a control red and vertical support for the four hl anemblies surrounding dw control rod; i

Control Rod Drive Housing / Stub Tube, safety related interns! component provides j

secess into the icactor pnssure vessel for control rod drive medianism.

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Shroud Support and Access IIole Covers, safety-related. kmnm shroud bafDe piste i

, carries the weight of dw shroud. sivuud lwad. steam separators, peripheral (bel assemblism.

j erte plata, and top guide.

CAN has been unable to ancertain whether any testine orinsnections haw heen aconnwdished I

in reference to dw ISCC phenomena outside of VY's ten year inspection cycle prograin on these w e NRC Projoet hianger Dorman stated that these componensa had not been checked at this refbaling. NRC Resident inspector Eichenhohz uss unsbie to give any detai of tne un you pian. We believe these s>Wems merit increased attation sinn the corrosive cracking of the shroud.

.\\t Alaine Yankee MO cracks were inwiicated in tulws in Llwsteam Cencretors. !!ow the uw of tlw plus point prolw a more nimaitive instrunwin half of the tubes (8.000) were found to be llawed. 7.elec. the maker of the plus poing probe has developed the super probe which is used in PWRa. Couki this 33*em he used in BWR's such as VY to idadify cracking?

We are tlwmfoie asking 3vur panel to support:

i A request that tlw NRC preside the data to dennonstrate certainty that the stooth rate in

'ita deterioration nf the shroud and the 25 component s>mems will not proceed to failum before the next refueling outage.

.. A mid tbeling inspection to eumine these 25 component s3 stems and the shroud ih A Hearing wid the Nuclear Regulatory Commission in attendence b explain to the community in Vermosa and klassachusetts the problems with Core Shroud Corrosion

• Cracking and the 25 component systems before the next redheling cycle in onier to clarify and demonstrate a review of the safdy issues arising from du cracksd shroud.

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(fkorn NRC ira R,yvii, Memo la file, Dated 950128; a takso Som Telcon USNRC sWWUN.' 2:

dated 950ilp) l AZRScomments ha.ve been tricorpurutedin Italics.

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COMPQNENT.,,

- tNdC COMMENT).

l CORK SPRAY SPARGER.

(' Previous Experience Insegsanular Suess Corrosion -

creakfas posect 'OK")

-Made qf1>pe 304 stainlus stui.

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.Sqfety.relatedinternal.

.Two citsular headers at diferent elevations with neo see boxpfpe sect luns which inject coolhtg 1

mster into the care in the event ofa Loss ofCoolant Accident to prwvent thefust' clad 6ng)vm l

meltigg'.

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~Accordng to a GPUNspecial report to NRC (Nov.1, J994) prwzenting results g(impdctions of ths care sprgy sporgerfor the C)<le 15 rejkeling outage, the "Prestaus experience

• qfereckng i

ofthe Oystnr Creek crses sprqv sporter wasJfrst identitledin 1978 as "one through mal (crock' l

in core sprwy sparger with air release observedfrom a smgle 208 degree crack. De nporj l

documents 28 odditionally cracks ident$ edin the core sprqy sparger 1980, and3 Identhted in 1982. Repair brackett were installed Cracks in the care sprny spargers can potentially alter theflaw ofcoolant to the core *and might lead to the seneration ofloose parts in the reactor pronure vessel.

NACInformation Notice 80-14 (Ref 4). addresses problems and outlines inspection

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requirements.

CORE SPRAY ANNULUS P! PING

(" Weld Blowout Hole" " Acceptable As I's7 l

Made ofI)pe 304 stainless steel.

l Safety.relar.edInternal l

The core spty amadut or core spray line trternalpiping is a ccaponent ofthe core sprwy

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.tystem whlek supplies coollag nier to the reactorfuel ausmblies during a Lass ofCoolant Accident toprewntJhe)kel claddingfom melting. The core sprny line connects the aternal core spepyp(ping to the core spray spargers.

-Anwding to O!!.iNspesialrepen to NRC(Nov. 3. I994) presenting the results ofloupactions l

Afshe care spray annadus pipingfor the Cycle 13 rqfueling outage, the " Previous operience" oferackng e'the spray line pipint wesfl?st observed in 1980 at "two indearians. " De report i

documents an additional 3 Indications ("one through weld hole

• and "2.llnear") were ident$ed l

In 1992 where

• Air releasefrom Wald L.3A is continuous.*

STEAM SEPARATOR

(" Bracket Ctacka " Accepted As is)

.Made ofType 304 stainless steel l

-Separates water dropletsyom steam generated in the core

-l29 stanfp(pes, also Type 304, wided to openings in Ihe shroud head

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STEAM DRYER

(*Dtyst Bracks r4'a gmg Arede 41}pe304steininesnel Asmaves arcesr moistww in stema criting the sreasit separators

<Dwing the R13 outage a ered wasidentyredin the steam apr breakat. As a twsn radiation emisesons)on the eenponent t3 rensthr), GPUN modertookan wannemanne arm mitigation $crt in the sp4nnentstoragcpool byplasma cutthng 1/2 inch holar at end rfp the creek SHROUD. HEAD BOLTS

(" Previous Experience Replaced Due16 IOSCC" 'OK")

Made ofinconnel 600 alloy, also susceptible to IGSCC Fastens shroud head to core shronttopflange.

': ORE SUPPORT PLATE HOLD DOWN BOLTS

("OK")

IRACKETS for:

("BentIToer" "OK Asis")

QUIDE BOLTS SPECDdEN HOLDER

' Ke.cht Bolt Tack W6ld Crack" "OK As Is" lEEDWATER SPARGER

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l Made of1)pe 316L and 31dhD stainlus steel.

-Safety relatedreactor internal component.

Uruler normal operation.fordwater spargerprovidos subcooling, hamngenous and un(form iemperatwo mhrite to helpprennt asynmetricalpower distribution in the oors. Dwkng a

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1.0CA. Ihefeedwaterspa ger becomespart ofthe HIgh Prusurn Coolant'loglection (HPCI)

Spetem to makstain on adepote reactor water lew!Into the care.

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-GPUN identyleda crackin the keeper bolt on thefndnoter sparger during R/3 Ihr crack war tack welded.-

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-During I972. larget circungtinventual crackt uwre detecte. din afeedwater sparger in otherBWRs l

and wrw attributedtoflow induced vibrations.

JP GUIDE

("Three Cracks Midspen* "OK As is" "three Previous Cracks No Measurable Crowth)

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Mode of1)pe 304 staksless steel l

.Sdery reletelconnowwne i

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.Provides lateral sypport to the reactorfuel core assembly and maintains proper spacing ofthe l

ypper ends pfthefuelassemblies.

.In a report to NRC GeneralPublic UtilityNuclear Identifiedsinetural cracMng q(the t@

I guide in August 1991. Hautver. NRC oficials responsiblefor the materials analysis and

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avoluattwo of0.nrer Creek reactor Internals claimed to only recently have been awarn Afthe

a. 2e a9ss e4:^6Y noe m.

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l Gneral Electric issueda service alert (AICSfL 071) in Nowmber 1 Water Reactor operators to inspect top guides andcore platesf crackin une notedon skese components in the Waergesun BWR in Germ

-The degree ofintimrion ofthe top gueir is in quanton, NIRSbeltev ring uns inspected while a lattice ofintersecting steel beanna widedtoget i

rim me not have been stupeared Rach square openknyfarmed& thn internant p:La lateral asprort arad maintaineproper spacingforJerue./kel assemblies.

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INTERMEDIATE RANCE MONITOR /

SOURCE RANCE MONITOR /

LOCAL POWER RANCE MONITOR

("IGSCC Crackha. Rep!aceableComponent").

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-The heutint are made oftype 304 stainfus stest b.h us ng proddes apen*Irationpathfor Insertion efmonito to he sur i

CORE SHROUD

("Significant Cracking S H4 Weld" " Permanent *RapairInstalled")

l The shr' sidis a segmentedcfindricalstasi Atructure made ofType J04 staln' len steeland o

weldedtogether.

SafetynlatedInternalcomponent

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proddu lateralrestraint to tlw reactor core, provides a refloodable compartment in the avwnt i

l of a Los Ofcoolant Accident, andprovida)br coolant waterflow to the core. Becesw the shroud connects to the core plate at the bottom ofthe reactor core assembly with the top g i

plate at the top ofthe reactor core assembly, any lateralshsj resultingfom a through well break ofa circumferential weld of the shroud outside ofa tolerance ofone eighth ofan tach

' Meuldprevent thefullIntenlon ofthe controlrodt. -

-Ettensive cracking was klent$ed on the He weld, approxinuttely the midrifofthe shrouds l

Contrwry to industry asywrtance to date, most shroud eraeking has been notedat ihn apper and i

lowerlevel welds oftheshroud

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-GPt,1N composted a *perneanent repair' utilising 10tle rodt attachid to I,he top and bottom of the core shroudinembly to prsvent lateral motion (Note: bottom portion efthe *)ts*Is hookad huo plasma are cut holes in plates qf Type 304 welded to the.throud as pet Rftbe original deogn, Vednerable to ICSCC]

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-The Bolling Water Reactor Owners Group has ident@ed that crackkog on the core hasniis an

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Indicator ofcracking that could be occurring to other r4 sty related reactor internals.

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-One ofthe originalreactors to show signs ofshroud cracking, the Wuergassen BWR. Germany, I

was not olland by the German moclear regulator to install a "fix". Instead Wuergassen has

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undertaken i2 commence a two year outage und replacement ofthe shroud at an uttmated t;ust ofas much as $65 million.

l SHROUD BRACKETS

(" Minor Indication in Shroud To Stackat Weld" "OK")

yster Cnekts the onlyplant that has shroud brackets.

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PART1 MOT IBEDICATED AS INSPFfPEI) during the RIS outses though ideadded e i

selbey related components and vulasrable to Stress conosion Csacidas (3CC) la "Bofilhi Weser Ramesorinternals Aging Degradstion Study * (NUR$GCR 3754), papered fbe NRC by Oak Ridge National 1.abannery, sepeessber,1993 and soiting water xsector ownsa oroup Meeting whh wnc, i

June 28,1994. These corgonents are subject to sgulations under American Society ofMechanicai l

Enginesis Boiler and Presswo vessel (ASMB BAFV) Code. Appendix 1, section il1.

l CORE PLATE i

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-Made of1)pr 304 stainian steel.

f Sqrfrynlatedinternalcomponerv l

-Locatedat the bottom ofthe reactor core anembig the core plateprovides structuralseeport to i

the reactar corefwl annablies andper/prationt in the plate provide Ruidance to control rod i

guide Ides.

l

-A GE servlee alert (RICSIL 071) advisedBWR operators to inspect the coreplate qtter seeirts extensin cracking qfthe coreplate at Wuergesun, Germory

-0) uter Creekpassedour this lopection becausethe earnponent was "Inoecessible."

CONTROL ROD GUIDS TUBES

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Made of1)pe 304.steinless steel

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Sqthry relatedcomponent Provides lateral guidance to a control rod and vert (col supportfor thefourfuel anembilar surmndtong that control rod. Errands v9om the coneet rod drin housing and through the holesin the careplate.

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CONTROLROD DRIVBHOUSING/ STUB TUBE 1.

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-Mode qf1)pe 304stainlesssteel Sqfetyrelatedinternalcongponent j

.Provides 9ecess into the reactorpresswa wsselfar congelrod bin mechanism.

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-Stub tubes are part ofthe readerprenure wssel on older model BWRs.

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• Leakage.has been detected in the gqp between the reactorpressure ussel and the ControlRod

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Drive Ifousingin other BWR s.

CONTROLBLADE

-Made ofType 304 stcialasssteel Providesfer reactor core reactivity control

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1

, ORFICEDfURL SUPPORT (OFS)FIECE

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l

-Provides lateral ss<pport madalistenent to thejitti assemblies as milas distribudng l

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l4 VESSEL HEAD SPRAY C0012NG NOZZLE (sanw as " reactor used nazdoi

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LPCI COUMJNG l

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D5FEREffTIAL PE3880RE AND UQUID CONTROL LptE i

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JET FUAEF ASSEREBLY i

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. JET R. ESERBRACE 1

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P Z: S L 0 2 Y %

11019.1M 0]M333H TOTAL P.15

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