ML20086H255
| ML20086H255 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee, 05000000 |
| Issue date: | 08/25/1972 |
| From: | Rosalyn Jones VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20086H243 | List: |
| References | |
| AO-50-271-72-02, AO-50-271-72-2, VYV-2223, NUDOCS 8401160185 | |
| Download: ML20086H255 (2) | |
Text
{{#Wiki_filter:' 1 h 90 S F) VictoiONT YANKICIc NUCLICAR POWER CORPORATION y SEVENTY SCVEN GROVC STRCET RUTI. AN1). Vi{lt.%10 NT 03701 ftEPLY TO: VYV-2223
- p. o. box 357 VERNON. VERMONT 05354 August.25, 1972 f ? Aq pl.7 )
yz ,w. h) .5 Directorate of Licensing f /d 2 3 ',
- - D Director
.I ri d United States Atomic Energy Commission p t Washington, D.C. 20545 \\, L .a 4 gh.*P /,Tg \\W, /,
Reference:
Operating License DPR-28 Docket No. 50-271 Abnormal Occurrence No. A0-72-02
Dear Sir:
As defined by Technical Specifications for the Vernont Yankee Nuclear Power Station, Section 6.7.B.d, we are reporting, the following Abnornal Occurrence as A0-72-02. Upon becoming aware of a problem discovered at another boiling water reactor, a detailed investigation of all drywell pressure penetration taps was conducted. This investigation consisted of visual inspection of tap terminations internal to the drywell to insure no blockage or plugs and additionally, pressurization of the tubing of each sensing line between each individual pressure switch and containment. isolation valve external to the drywell, followed by ventbg of the pressure into the drywell to ensure a free flow of air. 4 As a result of this investigation and inspection,.three drywell pressure switches, Nuders 5-12B,10-100C and 10-101C unre found to be inoperative as a result of open ended Tees in the,3/8 inch tubing between the containment isolation valve and pressure switeaes. Pressure switches 10-100C and 10-101C are associated with Automatic Depressurization System and Low Pressure Coolant Injection System respectively. These systems are not required to be operable by Technical Specifications under the present plant operating conditions. Pressure switch 5-12B is associated with the reactor protection system which provided one of the four, one-out-of-two-twice, reactor scram signals on high drywell pressure. Had drywell high pressure occurred, a reactor scram would have been initiated by the remaining pressure switches which were found to be in a satisfactory operating condition. 8401160185 721122 PDR ADOCK 05000271 g PDR 4749 CdPY SENT REGION L
r y qANKEE NUCLEAR POWCR CO VERMONT United States Atonic Energy Conmission August 25, 1972 Page 2 Reactor containnent was required during the period between 0300 hours, August 1, 1972 and 0157 hours, August 8, 1972 at which tine the reactor coolant temperature was in excess of 212*F. Subsequent to that time the reacter was in a shutdoun condition. During the period between August 1 and August 8, airborne contanination levels within the containment were found to be slightly above background averaging approxinately 5.0 x 10-11 Ci/cc. The maxinun level detected was on August 4, 1972 and was 2.0 x 10- O pCi/cc. Airborne contamination levels in the reactor building and at the stack, throughcut this period, remained at no detectable activity abcve background. The open Tees in the sensing lines were plugged, each line successfully pressure tested and subsequently vented to the drywell to prove a free flow of air. All drywell pressure switches are now operable and the integrity of the sensing lines has been confirned. Very truly yours, VERSONT YANKEE NUCLEAR P&'.R CORPORATION j }r~ Nf < / J', -{+ t"t j Robert F. Io es Plant Superintendent RFJ/rph 9 u_,
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ~ q oc g, U. S. ATOMIC ENERGY Com1ISSION DIVISION OF COMPLIANCE REGION III C0 Inquiry Report No. 050-237/72-07
Subject:
Commonwealth Edison Company License No. DPR-19 Dresden Unit 2 Excess Leakage Discovered during Local Containment Leak Rate Testing Prepared By: H. C. Dance M* / 91 '(Ddte) A. Date and Manner AEC was Informed: CO:III was informed by Mr. G. Diederich, Supervising Engineer
- by telephone on April 17, 1972.
B. Description of Particular Event or Circumstance: Local leak rate testing conducted as required by Section 4.7.A.2.c. during the current refueling outage has detected several valves which leak in excess of the 29 scfh Technical Specifications limit and will require repair prior to startup. Valves Failing to Meet Local Leak Test Recuirements Calculated Valve Function Leakare, sefh Comments 220-58B FW 18" check 5,000 Will require disassembly for inspection. Seat ring previously required machining in May 1971, 220-62B FW 16" check 5,000 wili 7 ;g.ro disassembly for inapection. 1601-203 A0 20" Reactor 75,000 Rubber coated seat found Building to Torus to be deteriorated. Vacuum Breaker Manufacturer recoating scat. Companion valve 20A, Icahage was 7 scfh (29 scfh limit). As precaution, station will recheck 20A prior to next scheduled test. $ % f,f I , // e ~- lg,lRcAT
O '~ ^ O 9 0 1 l l l l 1601-21 A0 18" U.1 Purte Can't pressurize Valves 21 and 22 have 1601-22 reibbcr scate chewed op. 1601 'n 11anuf acturer reacrted recoating uith improved rubber cea1. Valve 56 has yet to be inspected. G. Action by Licenste: The valves u111 be inspectcd, repaired, and retested to meet specified limitr prior to etata,.. p,eview of r ubber seal deterieratico in isolation valves in in progrer.. The licensee planc to report results of above testing and repairs in accordance uith Section 6.6.C.1 of the facility Technical Spectilcations. 1
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!!orri s, Illinoin 60450 gA./ .7, May 18, 1972 ,,,p)-W. c.. +.. ,,o i. Dr. Peter n. Morris, Director Divisica of Reactor Licensing p)s , 7.;. W y, , 'p/ _ U.S. ntemic Energy Cemission Washington, D.C. 20545 ip,t ~ ~ '
Subject:
Licenw DPa-19, prenden ;'uclear Pouer St n t i on. l'ai t #2, Section n.6C.1 of the Technical Snecificat ions Dear Dr. Morrisi '1his is to report ste' ten, in which, during priuary co.tain=cnta ccadition relating to the operation of the local leak rete te tr conducted no re ntired by Sectica 4.7.A.2.e of the Technical Specifications, five areas of lea': age, in excess of limits, were identified. 13t oi'1 r'M, INVESTICATIO'l jV;3 CC'OECTIVE ACTION Local 1cck rate tests of prinary containment isolatien valves were conducted, as required by Section 4.7. A.2.c of the penetraticas and Technical Specificaticas during the period from February 28 to May 9 At the t ime, the unit was shutdown and in the midst , 1972. of a refueling outage. the volunc bounded by the valves or scalb being tested to 4 of this pressure is then observed over a period of time to determine the Ica The decay rate according to the formulaj Leakage (scfh) = V (Pi - Pf) 35.38 T (ki - Rf) there Ve penetratica volume (ft3) T = time (hrs) Pi = initial pressure (psia) l'f a final pressure (psia) Ri e initial temocrature (degrecs Rankin) Rf u rinal tempercture (dedrecs Rankin) 35.3C = constant necessary t,a convert to sc fh. 1,7 j 4' y "D%enwr
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se Dr. Peter A. !!arris !!ay 18,1972 /.s a rcruit of there to-tc, the priun y containc.cnt perscanel air lo:k, tuo feeA.::ter ch ek vu.vea, cod fcur air operated butterfly valves in the pressure neppression systen ucre found to have Icahage rates in excess of Technical Seccifications Linit s, n. _ Primary Containment l'e t r en,e l Ai r l oc !- Initial testing of the persennel air lock indicated a leaha3e rate fren the lock of appre <imately 134 standard cubic feet per hour (scf h) which is approximately 4S07, of the allowable Icaka;;e for a single penetration. '1he scarce of enscnt ially all of this leakage was determiacd to be through the exterior upper handuheel sten real. It is believed that this leakage resultcd fren the large acount of use during the refueling cutage, pric to cc:.de0 ting the test. New packing uns installed and a neu packing gland for the stuffing box van f abricat.cd. After repairs the is k was retected ratisfactorily, exhibiting no measurcable leakage. Eccause the Icakage uas thro;;h only the exterior barrier of the perr.onnel Icak, prinary ccatainnent leakage to the environment would have been cero in t he case of an accident. (Tac interior barrior was ocr.catially leak t ight). b. Prenrure Suppression Systen air Operated Butterfly Valves 1. Torus / Reactor Building V_acuun Brenhor Isolation Valve (1601-20 T) Initial testing of the piping between the torus / reactor building vacuum breaker valves A0-1601-203 and 1601-31B indicated a leakage of approxir'ately 17,000 sc fh. Investigation indicated that the leakage was through A0-2-1601-203. Tais valve was removed fron the line and it was noted that the rubber seat was badly vorn and cracked. The seat uns nade of Buna-U rubber, rated for operation 0 at temperatures up to approximately 190. The valva was sent to the manufacturer for ima11ation of a neu rubber seat nade of a rubber ccapound, "r.PT", rated at 250 F steady state and 300 F for a short duration of time (10 hrs). The valve uns reinstalled and another leak rate test performed. The Icakage on this test was 3.071 scfh or 27.5% of the pernissible limit for a prinary contain-cent isolatica valve. Because valve 16Cl-31B, a check valve in series with the rubber seated air operated valve a0-1601-203, "a:; cssentially leaktight, littic er no l en'.a,e frr~ t. r i-ry < > . i'ine n t in the case of t an accident unuld have occurred via this penetration. 2. _Dryue l l Pun e Valve (160_1-213, Dryrell and Torus Vent fren Reactor Duiidine V., : v e (1 M1-2'n, ead Torm Purg/a ive (1 O 1-36) Oa Deccaber 3,1971, while scarchirc; : - creas of potential leakage f rom t he prinary c entainn it, a cise.. cf the valves in the prinary containn ent pur.;e lines ialicatcl thac varves A0-1601-21 and A0-1601-22 vere lea' ina excessively, at that tiac, a blind flange was installed
~ thy 18, 1972 Dr. Peter A. thrris int egrit y. 1ine to iuintain pel: ary contaf nucat on the'torge inlet uere removed from the A0-1601-?1 and no-1601.)2 anJ A0-1601-56 for prev'our.ly plannei repairn. r:y st e: durinq the r e t ue l f :n ou t a ;;e T.e sent: of these Valve me-l<,ol- % uce, rcpixed with a r> pare. Valve no-1601-21 a..' A0-1601-22 valves et r e f ound bc.d ly c roched. seats nado f a :t ory f or inst allation of new rubber were nent to the that the initial inctallation of "t:PT". The opin ton cf the vendor was of the huaa-N Lype rubber cent c on there valves was not done properly. s it e, instalitd and leak '1he repaired valver, uere returned to the^0-1601-21, n0-1601-22 and tested. 't h e final lett rate for valves f or an individual A0-1601-% uas 14.890 cc fh or 50.T/. of the limit isolation valve. All other rubber r,cated valves in the prennure cupprescioa system unro tented and ucre within Technical Specification 1.1mits, n review of all rubber seated valves utilized for primary contain-s If necccsary to determine adequacy of the caterial used. D. In progre:.s mnt t he:,e valves will be repaired or replaced. terLin', frc';uency ull) be increased by a as an interin twanure, from once per refueling outage to once every facter of approxiuately 6, three nonths. Feedvarer Check Valves c. initial testing perforned on icedwater check valve 220-5CB indicated The check valve van dinasceubled to cican and lap The cyccanive leakage. 'lhe valve was reatsembled, a 1000 psi the valve neating ring and seat. rate test perf on..el t o insure scating, and an air lea.s of this tect was 6.864 scfh or 23.47 of the limit hydror;tatic test conducted. The result for a primary containnent inolation valve. 220-623 indicated excessive Yne initial testing perf ormed on feeduater checkinternals of the va uachine r. hop under the direccion of the valve manuf acturer's reprecentativ leakage. The Tae clearance betueen the seat bushing and disc pin was redu . 'J 0 2 ". installed and the lenhage rate imately.014" to Foll owing repairs the valve 'cas rearr.e:61cd, f the limit fer a check uan perf on.;cd with resulrc of 3.680 scfh or 12.5*. o at isolation valve. priuary contai ' the primary function of there feeduater that I It thould be pointed outand ceal under high dif f erential precsure, hydrestatic coaditions. Laless a donble pipo rupture occurs these valves check valves in to close l l
t l Dr. Peter A. liucrin Ifay 18, 1972 trould have a water neal which uculd ccuenticily clininate Icakage via this path. 1 Sincercly, i .j "J at. ,h> 3.1\\c-w t_. i W. P. '..'ord cn ,g UN: G) D : rd s i l 1 I _.. _ _}}