TXX-9250, Proposed Tech Specs,Reflecting Turbine Valve Test Reduction, Including NUREG-1366 (Draft) Section 5.13, Turbine Overspeed Protection Sys (Pwr,Bwr), Pages 33,34 & 35
| ML20127G207 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 11/10/1992 |
| From: | TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | |
| Shared Package | |
| ML20127G205 | List: |
| References | |
| RTR-NUREG-1366 TXX-92503, NUDOCS 9211160366 | |
| Download: ML20127G207 (8) | |
Text
{{#Wiki_filter:. Attachoont 3 to TXX 92503 PagQ 1 of 1 lN570LYEN~1~!:N 3/4 3. 4 TURBINE CVERSPEED :00*ECT!:N
.:917:NG CONDITION FOR OPE:AT::N 3.3.0 at ' east o~e 7.roine Oversoeec Scotection System small ce :;E;ABLE.
- : : A B I '. : ' ' ::E3 1, 2*, sno 3' AC'!N:
- a. With one s:00 valve or one .ontrol .alve per nign pressare t roiae steam line inocersole anc/or with one stoo valve or one control valve per low pressure turoine steam line inoperaole, restore tre inocerable valse (s) to CPERABLE stctus within 72 nours, or close at least one valve in the affected steam line(s) or isolate the tareire from the steam sucoly witnin the next 6 hours.
- c. With the above re:virec Turoine Overspeed Protection System. otrerw:se inoperaole, .itnin 6 nours isolate the turbine from tne steam 5.co'.
5URVE!LLANCE RE0UIREMENTS l 4.3.4.1 The provisions of 5:ecification 4.0.4 are not applicable. l 4.3.4.2 The aeove required ove.soeed protection syste shall be cemonstestec
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- 3. At least once :er 11 c4 s Oy cycling each o the following selves inrough at ! east one comolete cycle from the unning positi:n usin; the manual test or Automatic Turbine Tester ( ATT):
- 1) cur nign pressure turoine stco valves,
- 2) Four nign pressure turcine control valves,
- 3) Four low pressure turoine stoo valves, and
- 4) Four low pressure turoine control valves,
- c. At least once per 14 days by testing of the two mechanical osersceed devices using tne Automatic Turbine Tester or manual test.
6 weaAs
- c. At least once per 21 c;js by direct observation of the movement of each of the above valves througn one complete cycle from the running position.
- d. At least once per 40 months my disassembling at least one of eacn of the above valves and performing a visual and surface inspection of valve seats (if acolicaole), disks and stems and verifying no unacceot-aole flaws. If unacceotatie flaws are found, all other valves of :nat type shall be inspected.
"Not acolicaole in MODE 5 I and 3 with all main steam line isolation valves are associated bypass valves ' tne closed position.
9211160366 921110 0 3R ADOCK 05000445 P PDR LUMANtN: rish - UNii a 3/4 3-50
i i ENCt.050RE 1 TO TXX 92503 NUREG 1366 (Draft) Section 5.13.
" Turbine Overspeed Protection System (PWR, BWR)"
pages 33, 34 and 35 s 1 i f i 4 4 4 1 i f i 4 4 4
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l 3 Instrumoruauon l i DWT pomts for system operation wtuch are,below the dessa there are no astoclosure interlocks on the l temperature and pressure knuu of the RHR system. An RHR sucuan valves removmg the overpres. ' mterlock prevents the valves frorn bems opened when the sure intertocks from the RHR suchon valves RCS presure or the RHR pump presure is above the the best RHR section arrangement for RHR system design pressure. A second interlock, the based upon this analyss. when aner. a utodosure interlock (ACT), is provided to autorasumuy locks 4 e pienent, loss of RHR suchon is the dose the valve tf the RCS pressure mcreases above a set largest contributor to core melt frequency. pressure. However, when the interiocks are not present, the core melt frequency due to loss of RHR By letter dated August 4.1987 (Shdfer,1987a), Paafic sucuon is coraparable to or less than the v. , Gas & Electnc Com ny (PG&E) requested staff LOCA core melt frequency for the best esti. concurrence with its 10 CFR 50.59 evaluauon which de. mate cassa. termmed that removal of the RHR autociosure interlock funcuon does not consutute an unreviewed safety ques. De AEOD report contdoded that, even though it was non or reqmre rnodifitsuon of Techracal Specdkauons. most ukely a good idea to remove ACI. the efecss of ACI The NRC staff focused its review of this issue on the removal upos plant afety must be evaluated on a plant. effect that the proposed change has on the Event V (in, by plant bass because of numerous plant.specdic ddler-tersystern LOCA outade of the contamment) sequence. ences. De PO&E submatal (Shiffer,1987a) contains such a plaat speanc analyssa. The staff reviewed the probabnirJe risk asseernent (PRA) subrnatted by the Diablo Canyon Licenses to sup- ne Wamar Nors Group, however,has submit tad a genene for the deletion of the autociosure port this proposal and also explored alternatsves to total removal of the ACI cuenstry, citerlock (W -1173Q mois G , d CapabGhyinFWRs," ne proposal. as agreed to by the NRC staff, wiu cot.ast remunmends (but does not require) that ACI be removed. of hardware and procedure modificauons. Other licensees should review their safety bases for the PG&E proposes to remove the autoclosure interlock autoclosure interlock of RHR isolat. ion valves to deter. funcuon from the RHR system sucuon valves. ne open nune d removal of the aetaciosure interlock results in a permassive mterlock wdl remam intact. An alarra wdl be lower core melt (i iwi and, if it dosa, snoeld propose added to each valve which wdl actuate if the valve a open removsag this requirement from their Techsucal Specifi. and if RCS pressure is above a value set between 390 pe8 canos.a. and 450 pus which is above the RHR valve open penas-save set pomt. In addition. the status lights on the opera- g tor's panel who mdacate that these valves are open or dosed wdl remair funcuonal afte p aer has been re- e Analysesshowthatrenovalof theastodosureinter-moved from these valves. lock decreases the care melt probabdary. ne Licensen also developed impmsad operating proce. * *!be Weninghouse Owners Oscop has made a sub-dures to assure dosure of these valves. nasual to the NRC mat propeans to remove the asociosure sterlock. ne f. nam re , t4 for removag ACIare given in a report from the C A for Analyes and Evalamoon of Opera.
- Rasohnion of OW, h of W Cpabdity m tonal Da'.a (AEOD) esacerung deny heat removal FWRs." r===W (bot does no. r,mre) mat -
problems at U1 pressmand weser renaars AC!be rmed. (AEOD/C303). His esport posats out thas, of the 130 loss of RHR evenu that wars documented at U.S.FWRa between 1976 and 1983,37 were cnamed by the amenanc Other owners groeps bandes Westinghouse should de. desure of the sucuorunotation valves.no AEOD report also quotes a study prepared by Sanden Laboratory for the m ime ces malt riskis W or lower wie me ACI dalmed. NRC (NUREG/CR-4335) whi:h evaluated the compet- , mg nsks associated with RFiR sucuan/molation vaht clo. sures and Event V. Sandia cenduded that: 5.13 Turbine Overspeed Protection i System Testing (PWR, BWR) l De lowest core melt frequency due to the I comomanon of los of RHR sucuan dunns cold De present Tehaal Spea0 cations for a PWR reqmre a shutdomi and V LOCAs is obiamed when tortune overspeed prosecuae system to be operable m ' 33 NUREG-1366
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i 1 5 Instrumentauen 1 i l Mode 1.The systest must also be operable in Mode 2 and ne issos here is not whether the test should be done, bot j J if all steam paths to se turbme are not isolated. rather how often is should be done. I ne Techmcal Specifications for the turbine overspeed As dommed earlier (see Sectaos 3) tartme overspeed 3
- protecuon spters m a BWR are equrvalent; they requare protestaan system teams is a major scarse of reactor tnps i the system to be opersbis in Opentmg Condaion 1 and,if whsdi comr during or as a result of survedlance testag. !n the MISIVs are open. m Operstmg Condition 2. addnaon, licensees have stated that this tem is hard on the l
steam system, cauang relief valves to lift and addmg ther. i ne Techrucal Specificauons " split report" has deng. rnal and ruechanical stresses to the pipeg. I nated this techrucal spectication as one which may be l relocated from the Techrucal S ications. However,it Personnel at the Saa Onofre site asumate that perform. i has become apparent in orming this study that, ing es weekly tem takes a crew of 'adamaa appron. because of the problerns caused by the turbine valve test. mately 3 hours (per crut). De monthly survedlance re. sng, faster acuon u called for, Dere are several reasons quares apprmunately 6 hours per unas. i for this: The concern in this mee, lwu, is not burden on the l' I First. this survedlance has caused a enah' number of licuases but the asenber of inadvertent tnps and wear on reactor inps. es eqmpment. l ! Second, the survedlance results in some wear to the Turtune overspeed pnxection is typcally redundant and i valves and stress to the steam system. h If a turbine accelues from ns monaal speed j (e.g., dos to a change in load) the nonnal turbme control i Third, whde the test is being done, in order to avoid a , symem pa=h de control (or gowner) mins to mp. reactor tnp, the steam flow to se turtune som be re, idly usam me speed 2 es proper set poet. l duced. His is done by other reducing reacsce power, i which results m a redocuon of capacity factor, or by in addruon m his, Ms W boe haWd j elecinal W m nas p am de.
- dumpmg stearn to the condenser, which could be deln. mzted ta Sectaan 10 each plant's F5AR(finalafety mental to the condenser because of the darnage done by i vibration of the condenser tubes when large traconu of I'E*")'
f steam bypass the turtune and enter the condenser. Mahanical overspeed protectaon which in WAt i of the electrohydraulic controller (EHC)is primded by l In addition, because power must be lowered to perform - es anchaamal omrspeed trip inatam ed is set m this test, the test becomes very difficult to do at the and of ,,,,,, ,; (,M) 110% d mud spud. cvele when there may not ce enough dilution capability (in a PWR) or rod worth (in a BWR) to owrnde sanon. Elecincal overspeed protection, whms is est at (typically) 111J% W rated speed is pumded as a backup to me ne surveillance testag requires raovmg each of the tur- mechanual m - M aip devna. no elazncal trip sole. bme valves through one cycle (from the she pannon noud vehes are deanergned to tnp the turttee spon re. pnor to the tem, to fully closed, and rerunung to the camag an open contacs from the EHC whsh represents ongmal pomuon). De test is typestly performed by a an ovespeed condidon. control room operator with an obstever at the vahe.no test vertfies freedoen of movement of the vehe compo. In addition, each sama line to the tartmas typically has , nents that is, a venSes that mething shtlits es vehe two vahus in senes so that a faBare of a angle vahe from cioeng. Wesunghouse has mated (WCAP-11525) snact cease the turbine to overspeed. that -{t]his type of tesung is beneocial for (1) desemag non. or slu ggish operation of tha valves, and (2) Maannea. De present requeminents for the test fregoency are non of gross outweed appearance of vahe anah based on turtmas vendor ma-ad- (Trasmael, 1987).This test sterval was developed (1r ional sans and ne surwesilance requirements for vehe operabihty est camed over to auclear emits dos so the antarmy in de. i I sure that all the turbmc steam inlet vahus are capable of egn. Fount units produced aram with much greater par. l closeg to protect the tustrine frorn encasuve overspeed. ticalate (impendes) enataan than is permated in noctear Protecuon from acessve tertnne onetspeed is requred anas.name unpemies requred more frequent gehe sur. smce excesstve overspeed of the turtune could generate vallance to ensure rehable operation. Also, tomai unas potentially damagmg massdes which could hit and darange and earty PWR nans utahsed phosphate chsausry a ther safety.related components or strue:ures. *** The phosphate based chensary control con. tributed to vahe inoperabdity. For cample Turkey Pomt Thus, the test ts benefical in some ways and serves a Plant Unit 3 had stuck open turtune stop vahes wtuch safety funcuen. were found dures shutdown. De cause was phosonate NUREG-1366 34
- a maum
- manen 1-i DRAR !
- deposrts between the shafts and bushmgs of the valves tion moruton on BWR main steam lines. De engmeered I
- (NPE4). .
miety features actuations are %sically isolation funcuans ! and air cleanup fanciaons Many tediation maruments i A rewew of the operating hastory of turMne valves perform a monnonag function; these innruments mani. (NFE-2) shows that failures of these valves do occur and ter for reactor coolant leakage, acedent condmanas in
- that, unhke some other Techmcal Spaanrations tests contamment, and the release of gaseous and liquid whsch do not find failures, these failures are found dunns ef0 cents.
l the turtute overspeed tesung. However, the number of i inps attnbutable to t!us testag is s43mficant. As with other mstrurnentation, radiation moniton are i reqmrod to undergo three types of survestlancat: a chan. ne NRC has granted mcreases m the testmg interval for nel check, a channel funcuonal tea, and a calibrauon. In j turtme ovenpeed prosecuan testms. For aample, in a addition, a soone check is perfoaned. I letter dated Apnl 16,1984 (Engle,1984), the staf ap. I proved changmg the requirement for cycling each of the The capability to source check provides an integral venfi.
- turtnne valves from every 7 days to every 31 days for Norg aten of the reponse of the detector. This is generally i Anna Power Station. Urut 1. required anonthly or before using a system which would l release potentially redacecuve fluid. ,
i Another factor in this case is the 'arbine rnanufacturers' _ I recommendauons about the tesung frequency of these The teams of radiation nw=ht produces a agmGcant valves. In some cases, these frequencies are comparable nuanber of isolations of es control room, fuel headlag to the emstmg Tectuusal Specifications. balding, aanlaary Wdings, and wious procen lings. la j addition, the tesung requares egnaracant Imasses ma5. 4 The NRC staff recommends that, where the turbine 1.acensees also atated that the frequent tesung toads to
; manufacturer agrees, the tesung interval for turtune desmde 2e eqmpment. De instrumentation sua he valves as part of the turbme overspeed protecuan system removed from ceanets and remserted. A maponey of the surveillances be extended froen weekly and monthly taas marurnentation is self checking so that mas fanares ed!
l to mne test donc quanerty, in which a direct visual obser. be found in this way or by chanstal checks. i va m will be made of the movement of each of the turtme valves currently required by Techmcal Speafica. De San Onoin ucensee propmed eat ee survaata= uons to be tested. tem intervals for radiation anonnors be extended. De. tailed infonaanon on failure luacry was provided for A quartuly test w%wds to the most stangent valve some monnors.1:1 addition, et San Onofre lacensee l' testmg requirement of the ASME Code. made es fouowng points in support of 2e en-m of the surveillance test interval. Findings The radataan monnors at San Onofre have had a maamal e Turbme mye testag reqmres a redocuan in faGure lusory.De faAnns am normany of ruote meter l power and ts a mam cause of reactor tnps durms ahtm whid would not impact 2e afety funcuan. In l tesung, addition, chsamal checks and faGm alarms would detect ImAures the recitare correcove acnon. j e Testmg of the turbme valves is necesary and the D eans whistesamm phh l j
}"*""'*"'""""**d**"' detenened as part of this andy. It is therefore dilBash to maa me s= 0.ofa - and de.g. d empo.
late it to other reasser stas. Tais appean to be a atuation f Recommendaties in which 6 *!'achacal eWaa== au. vedlance mqmrments could be attised to decranse the Where the tustnne manufacturer agrees, the turbme 4 valve tesung frequency domid be changed to quart.rty, fregoency of survedlance tesung on rehable radanon monsares symems while reqmrms more fregnant temung 1 on adataan massan when an act as rehabia. t 5.14 Radiation Monitors (PWR, BWR)
- It does seem r===amaM* to give relief on es nw y of The Techmcal Specificanons contain three categones of channel fuecmonal tems anos thans asess do not imotve radiation moruton
- those used for gaseous and liquid the senscr (radiation mensor) itasif, Derefort, in order effluent morutormg. those urst for momtonng an arm - to decrease the lacensee burden and increase the avad.
- and indicatmg the radiation levet and those that are pan abihty of the radiation monnonng syneas, the NRC staff of the reactor protecuon system and engmetred safety recommends that channet funcnonal tests on radiation features a:tuation systems. De ordy radiauon moruton roonnonng equipment be performed quanerty. For some j wuh a reactor tnp funcuon are the mam steamhne racha. redauen monnones eqmpenent, thas survedlance is 1
35 NUREG-1366 i i 4 4
4 d 2 i 4 ENCLOSURE 2 TO TXX-92503 Siemens letter from Mr. P. C. Hosbein to Mr. C. L. Terry, dated June 11,1992 (including Figure 1) .i i o d i 2 4 i i ) t
9 SIEMENS June 11,1992 - k Mr. C.L. Terry Chief Engineer Comanche Peak SES TU Electric Company P.O. Box 2300 Glen Rose. TX 76043 Re: Main Turbine. Generator ATT Valve Test interval letter from Mr. D.J. Reimer Dated May 4th,1992 J
Dear Mr. Terry:
Based on the current design of the main valves and control system on the turbine, and the latest failure rate data, we recommend a monthly interval between ATT valve tests. A testing interval of six weeks would be possible if additionalmonitoring sensors were on each stop valve. A test interval of six weeks is permitted, as long as there is no degradati of the closing times of the stop valves. The result of a quantitative evaluation by Siemens of the failure probability of an overs trip and protection system as a function of the test intervals for the turbine control an valves is shown in the attached drawing, M TOKA-02579. If you need further information,please let me know. Very trul yours, , ' 1 7
' / . (' i't 0)1 b$
Peter C. Hosbein Manager. Service Development i Enclosure cc: B.S. Dako w/att W.J. Cahill w/att H.G. Haby w/att 00(a J.J. Kelley w/att D.J. Reimer w/att P.B. Stevens w/att PCH:Im Siemens Power Corporation 4100 Sonng vaney. Sude 205 Dallas. Texas 75244 (214) 980G65 FAX: (214) S312538
FIGURE 1 l 1 10-5_ L b Confidence
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.,.ma =. Interval
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r g permiselbie - - Wh s ,- 1 s 1 10-e . ,, 610'-7
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y
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. 1 1 1 0-7 . [ . ', , , , ,
1 2 4' 6s.4 8 10 12 we.k. Recommended Test Interval (Morithly) TEST INTERVAL Time Between 2 Teete
- Based on data compiled before 1984 ATT Valve Testing Interval
% 27, im WTDKA 02579 .- . . - . -.. . . - - - - . . - . - . , _-_ - . -.}}