ML20101M366
| ML20101M366 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 06/30/1992 |
| From: | Creel G BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9207080204 | |
| Download: ML20101M366 (13) | |
Text
f B ALTIM OR E^
GAS AND ELECTRIC 1650 CALV".RT CLIFFS PARKWAY
- LUSBY, MARYLAND 20657-4702 GEonoE C. CREEL
.Iune 30,1992 VaCE PREStOENT NUCLE AR ENEROY (480)#60-4486 U. S. Nuclear Regulatory Commission Washington,DC 20555 A'ITENTION:
Documeni Control Desk
SUBJECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 Request Relief from 1968 ASME Boiler & Pressure Vessel Code Section III, Article 9 Gentlemen:
Baltimore Gas and Electric Company (BG&U) requests permanent relief from ASME Boiler &
Pressure Vessel Code Section 111 (1968 Edition), Article 9 as allowed under 10 CFR 50.55a(a)(3).
We specifically request permanent relief to allow a stop valve to remain installed downstream of a thermal overi ressure relief device for the tegenerative heat exchangers of both units. Compliance with Article 9 would result in hardship without compensatory quality or safety improvement. The stop valve is maintained in BG&Es lock Valve Program.
We believe that our existing design satisfies the intent of our 1968 ASME Section 111 Class A cons;ruction code. Ilowever, current code editions and several code iaterpretations issued after our construction permit date (July 07,1969) do not allow our system configuration. It is not possible to obtain an interpretation of the 1968 ASME Section Ill. Therefore, we request permanent code relief to eliminate any ambiguityin our application of the 1968 ASME construction code.
1.
CMfPONENT FOR WIIICII REttEF IS REOUESTED Permanent relief is requested for manual isolation valve CVC 188 being located downstream of check valve CVC-435 [see Attachment (1)]. The regenerative heat exchangers (one per l
unit) transfer heat from the ha' Reactor Coolant System (RCS) letdown Guid on the tube l
side of the heat exchanger to the cooler charging pump RCS Ouid on the shell side of the heat exchanger. Spring loaded check valve CVC-435, located in the aypass line around CV-519, provides thermal overpressure relief protection for the regenera.ive heat exchanger in the event the charging header is isolated and hot RCS fluid continues 'o Dow through the j
heat exchanger. The heat exchanger was designed to the 1968 ASME lloilcr and Pressure l
Vessel Code Section III, Class A (stamped C).
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Docurnent Control Desk hme ?O,1v92 Page 2 II.
CODE REOUIREN1ENT FOR WillCII REI.IEF IS REOUESTED AShiE Boiler and Pressure Vessel Code Section 111 (1968 Edition), Article 9 paragraph N-910.8 states:
"Any stop vahc cr similar desice on the inlet or discharge side of a protective device provided in conformity with N 910.7 shall be so constructed, positively controlled and interlocked that the requirement of N-910.1 will be complied with under all conditions of l
operation of the system."
III.
PROPOSED ALTERNATIVE We propose to maintain our current system configuration. CVC-188 will be maintained in our Mcked Valve Program. Valve position is ensured and maintained by a standard Operstions' lock and two lock wires. Additicaully, a stainless steel informatian tag which states that the lock and lockwires are required to satisfy AShtE code requirements is attached to the handwheel for CVC-188.
IV.
SUPPORTING INFORNtATION A.
SEOUENCE OF EVENTS Recently, questions were raised as to whether the location of a manual isolation valve (CVC-188) downstream of a thermal overpressure relief valve (CVC-435) complied l
with the original intent o the AShiE construction code. The construction code for r
the regenerative heat exchangers, 1968 ASME Section 111 Article 9 paragraph N-910.8, requires CVC-188 to be positNely controlled and interlocked.
Baltimore Gas and Electric Company has revic ved the vrious ASME code and code interpretations for locating stop valves downstream of pressure relievin; devices [see Attachment (2)]. The regenecative heat exchangers were designed to 1968 ASME Section 111 Class A but stamped Class C because 10 CFR 50.55a did t.ot originally require N vamps.
In order to octter understand the intent of the 1968 Section III Class A requircracnts, we researched the requirements of 1968 Section III Class C. For Class C pressure vessels, the 1968 edition of Section III paragraph N-2111 states that, "The requirements of Section VIII of the code shall apply to the materials, design, fabncation, inspection ano testing, and certitication of Class C vessels except that the following additional requirements shall apply." Paragraph N 2114 goes on to state that for overpressure protection, the rules of Section VIII do not apply and the overpressure rules for ASME Section III Class A (Article 9) shall be substituted. It is l
very peculiar that the 1968 Section Ill Class C code refers the designer to the Section Vill requirements for everything except the overpressure protection requirements.
The 1968 editica of ASME Section VIII paragraph UG-134 (e)(2) states that there shall be no stop valves between the protective device and its point of discharge except
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Document Control Desk
' June 30,1992 Page 3 under the conditions set forth in Appendix M. Appendix M paragraph UA-355 allows stop valves on the discharge side of a pressure relieving device provided that the stop valve "can be locked or scaled in either the open or closed position, and it shall be locked or scaled in either position only by an authorized person." If our regenerative heat exchangers had been designed to 1968 Section Vill, the only code requirement for CVC-188 would be to have a simple locked valve. Ilowever, the regenerative heat excharigers were designed to 1968 ASME Section Ill Class A which implies that the overpressure controls of Section Vill are not sufficient. It appears that the Section 111 requirement of " positive controls and interlocks" means something more than a simple locked valve.
While there are no interpretations of the phrase " positively controlled and interlocked" for the 1968 Edition, the post construction era ASME codes and code interpretations explicitly state that a locked valve is net suflicient control for a stop valve located downstream of a pressure relieving device. Since it is not pouible to clearly determine the 1968 ASME Section 111 Code intent for the words " positively controlled and interlockedi, BG&E is seeking NRC code relief.
B.
ANALYSIS The existing system configuration was evaluated.
Baltimore Gas and Electric Company believes that our current system configuration adequately controls and satisths the intent of the construction code. The design of the system facilitates testing and maintenance activities. Without CVC 188, we would be required to freeze seal the Class 1 section of the charging line to run the required local L.cak Rate Test (LLRT) on CVC-435, CVC-188 is temporarily throttled to adjust the flow rate to the pressurizer auxiliary spray, however, it is still capable of accomplishing its pressure relief function.
We investigated the possibility of physically removing the bypass line (CVC-435 and CVC-188) around CV-519 and installing a relief valve for the regenerative heat exchanger. This would require a costly major plant modification which can only be donc during an extended outage. We also evaluated the possibility of installing electrical / mechanical interlocks between CVC-188 and CV-519. 'llis would require Control Room panel modifications. The cost associated with either of these two options does not offset the minimal increase in safety.
C SAFETY SIGNIFICANCE CVC-435 provides thermal overpressure relief p;otectian for the regenerative heat exchangers. CVC-188, a manual isolation valve, facilitates testing and maintenance of CVC-435. CVC 188 is in our Locked Valve Program. There are administrative controls and physical restraints in place to prevent inadvertent closure of the stop valve. CVC-188 can be manually closed to perform the testing and maintenance activities for which it was designed. Controlling CVC-188 by the Locked Valve Program poses no threat to safety.
i If a thermal transient were to occur with all normal flow paths and the overpressure l
I relief line closed, the regenerative heat exchanger could be damaged. Adequate design features (check valves) are in the system to prevent a loss of RCS inventory.
MCV-269 would be used for charging via the I-ligh Pressure Safety injection header.
Document Control Desk
' June 30,1992 Page 4
'Iherefore, maintaining CVC-188 in its current configuration does not create a significant safety concern.
D.
CODE-REOUIRF41ENT PERFOPMANCE IMPACT The options available to upgr.ide the system conGguration to current code editions and interpretations would require either removing CVC-188, replacing CVC-435 and CVC-188 with a relief valve or installing interlocks between CVC 188 and CV-519.
All of these optior.s present a signiGcant hardship without a compensating increase in the level of quality or safety.
V.
COMPENSATORY ACrlONS Maintain CVC 188 in the Locked Valve Program and with two additionallock wires.
VL JMPLEMENTATION SCIIEDUl,E hiaintain our system in its current configuration with a manual isolation valve (CVC-188) located downstream of a thermal overpressure relief valve (CVC.435).
b'AFETY COMMI1 TEE REVIEW l
The proposed relief request has been reviewed by our Plant Operations and Safety Review l
Committee. They concluded that compliance with Article 9 paragraph N-910.8 would result in a hardship without a compensatory improvement in quality or safety.
Should you have any questions regarding this matter, we will be pleased to discuss them with you.
j Very truly yours,
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Attachments: (1)
System Configuration (2)
Code Excerpts and Interpretations l
E+m se sm Document Control Desk
' June 30,1992 Pagc 5 cc:
D. A. Brune, Esquire J. E. Silberg, Esquire -
R. A. Capra, NRC D. G.' Mcdonald, Jr., N RC T. T. Martin, NRC P. R. Wilson, NRC R. I. Mcl.can, DNR J.11. Walter, PSC l
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4 4
4 ATTACHMENT 1 SYSTEM CONFIGURATION i
FROM RCP 'S
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CV j
PZR 517 REGEN 1 r HX
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CV 518
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TO RCS L OOP 128 7j
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TO HPSI CV w 2 519 rm TO RCS LOOP llA I
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N X_
CVC 3 r CVC 435
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A k y
CHARGING PUMPS
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I ATTACHMENT 2 CODE EXCERPTS AND INTERPRETATIONS s
1968 SECTION III
.. SUBSECTION C..
Requirements for Class C Vessels I
' ARTICLE 21 l
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G< nemi Requirements l
l N.2110 REQUIRDic.....:
C vesseis that may emn:ain substanets -hose
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level ei radine:ivity is such that thir predue-subs.ec.ti.on. C. e.svers r.e:uirements :or yesses.._
etasstfie-as Class C.
.i gn, stoe. n, or 23, ;,ab.ieet to reculations of i
d rat or Loca..incismet.
ee e ions.
- N-2111 The regiremen:s of 5ee: ion \\111 sf the Code sha!! apply.co the =a:erials.destra. faheien.
N.2114 The raies in pararaphs CC-125 through tion inspection 'and testina, and certification of CG-134 of See: ion VIII of the Code shall not Class C vessele except that the following addi, apply and the re:;uirements of Ar-iele 9 of :his tional repiremen:s shall apply.
Section shall be sohstituted therefor.
%2112 The rules in Par. C-1(a) of See: ion Vill 3 2115 Class C vesseis shall be stamned *!:h of he Coce shall act apply to Class C vessels.
the letter S' below :he Code U symbol in the L2113 The rule s o f' parapaph CLO (a) of stamping shown in Fig. CG.118 of See: ion VIII of sectiot. WII of the Code shall apply :n say Class the Code.
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1968 SECTION III, ARTICLE 9
- .7!0.7 Taile pressure rel!eving devices need not. be installed directly on the vessels which they serve. to protect. no stop valve or similar P device shall be'placed relative ~ to 'a protective' i
device required for the protection of any vessel so that it could remo^ve the protection afforded to the vessel. except where such stop valves or other, devices are shown to be required in the di.
- rect interest 'of system safety 'or for the purpcae of in-serdce inspection - and testin5, subject.'
however, to the requirement.s.of N-910.8.
N 710.3 Any stop valve or similes device on th'e inlet or discharge side of a protective device pro'vided fi'ionformity with N-910.7 nhall be so constracted, positively, controlled and interlocked j
that the 'requireinent 'of N-910.1 will be complied with onder all conditions olopercion of the system.
. i ny 9
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-1968 SECTION VIII UG 134.!sstallatio _
(e) T"nere s'aall be ao intervening stop'vslNs beiwees' the wssel.,and'its, protective devke or devices, or ktween the protective device or de-
' vices ind'the polic'of dise* arp, excepu a
(1) Whea' theie 'stop velves are so. con.
'stnetd or pos,itivelv.cose,elled 6: the closing *
.of & inaximam suinkr' of' bloe'i v'alws possible Ecoe~ time will not riduci&"pressvne-relievia6
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capaci'y~previded,by the anai!=eted relievias t
devices below the aquirma_ relieving espacity; or
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(3 ' Undir the 'conditioni set facth in Appen.
diz M.
l APPENDIX M i
i Instanation and Operation s
l'A-353 5 top Valves. o de Discharge Side of a Pressere-Relievice Device (See Par. UG-134(4).)
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, ' ' A full-erta stop valve mav.be placed onthe dis.
dafp ii'dii of a psdn'Eilievisg~ device whe's its_ discharge is connected ~ to a common header with other discharp 1.ines kom other pesswe.
mileving devices on nesby vessels that are in
' ' peration. so thet thir stop valve when closed o
will' pnvent = discharp frim 'an~v ' co' nae'dted
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operating vessels from backing up beyond the ivalve'so closed. Such a stop valve shall k so ar-:need the it can be locked m sealed in eiser the cien or closed position and it shall be locked e Sealed in either positioihaly W an authoridd '~
penoa.hsen it is to k closed while the wssel is in operation. aa ausorized person shall k pas eat. and he shall oemais scationed serv.
he shalt again Toek or sed ek stop valve in se apes positica Wiore leaving se station. U:ier so condicios should this valve k closed while the vessel is is operation ex==pe when a stop
' valve os sc talet side of b safety n!Ier*ss de-vice is lastal!.d andis Srst cla ed..
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ASME SECTION'III CODE INTERPRETATIONS ihterpretation:
III.80-67
Subject:
l
' Section 111 DiWslon 1,NC.7142 Provisions When Stop Valves Are Used DateIssued:
April 16,1980 -
Fde:
NI.79 241 1 Question (1): What is meadt by the te'rm " controls aiid interlocks" ashou'nd in NC-714
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Reply.(1):.The " controls and'inteslocks", referred to in NC-7142 are pressure eming devices zequired to pFrmit pressure relieving funcaon to be met at all times.
Question (2):, May administrative controls.such as, operating procedures goveming the use and applI-cation of the system be construed'as the " controls" of NC.714" Reply (@:.Yes, operating'pr6cedures may be the necessary part of the electrical and mechardcal controls required by NC.7142.
Sec:en ut -laur;maaiers No. 24 Ill-1-40-mt. m-1 as-01 Interpretadore 115-1-40 47R Subjec::
Secoon III. Division 1, NC.7142 Provisions When kop Vakes Are (Jsed (1980 -
Edidon)
Date !ssued:. March.1,1.989 v
File:
N!79-241*
J:
Quesden (1h Whatis mear:: by 6e :erm c::n:rcls andinterlocis as ict.md in NC-71427 l
L-Racly (1h The corarols and interiocks tierred to in NC.7T42 are pressure ser: sing devices which L
- would ac:rvaze the stcp valve to provide fluid access to the relief valve. $ereoy assurLig 6e pressure reiledng func::cais met at all nnes. '
Quesdon Ch May Mrdstddve corurols.such as %W :nocedures acuerning te, use and appru:stkn of 6e si/ stern be construed as se cerarols of NC-7142?
ReplyCh No.
Note: Interpretadon 111-80-67, orngmalt isueci April 16. I980, was revised to be consistent with l
freerpretapon '(18-61-131 issued ~ Nc wh '9, 1931. The above ff%m supersedes la%mM !!I-80-67 which appeared in Volume 7, page 55.
.a 1989 SECTION III, CLASS 1, 2 AND 3 NB-7142 Provisions When Stop Valves Are Used (c) No stop. valve or other device shall be placed.
'ela:ive,to.a pressure relief devu:e so that it could r
, recuee the overpressure protection below dat reqmred
. by the rules ofthis Article u=less such stop valves are constructed add i=s:a!!ed wit!i controls and intedocks
, so that the relieving'espacity requir- -WofNB-7300 are met unds aB conditions of opeation of both the syst=t 'and the stop 21ves.
' ~ (b) Simpkt =dministrative centrol of stop valve pca-
'.sitico is not acceptable.
' fc15;op valves shall have independe=t and diverse intedocks to prevent. valves &cm being closed during
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a11 condidons of, system opeation when the pressure relief device is n'eeded to meet the r: quire =ents of NB-7300.
(d) Stop valves shall have independent and diverse intelocks to assure that de valves will autoeily open and remain open dur=g all eenditions of system opeation when the pressure relief device is needed to
=ect d~e require =ents of NB 7300.
e> Means shall be provided such that the opeaticu of controls and interlocks :an be verified.
NC-71C Prtmasons When Stop Valves Are dsed ND-7142 Provisions When Stop Valves Are Used No step valve or other device sh2H be pbced rela:ive No step valve or other device shan be placed relative to a pressure relief device so dat it eculd reduce the
'to a pressure re!Ief device so dat it could reduce de c%- gm Jon beIcw that e.gsrud by the ovepressure protec:ica below dat required by de
' rules of dis Article, nnie" such stop valves are ceu-rules'of dis Article u: Jess such stop valves are cen-s::.2c4 and instaHed with centrols and intelocks so structed and installed with centrols and interlecks so that de reHevi:ig enpacity requirements of NC 7300 that de relieving capacity requireme=ts of ND-73C0 are met tmder aH cenditions of opeanen of both the
'.are met under au conditiens'of opeatica of bcth de system and the step valves. Means shall be presided system and de st* valves. Means shan be provided such dat de e-% of cen=ois and inte!ceks can "such that de opt.r.cn of ecacrois and intelecks can be ve:ided.
be verified.
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