ML20086S297
| ML20086S297 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 05/23/1974 |
| From: | Stallings C VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| Shared Package | |
| ML20086S284 | List: |
| References | |
| AO-S1-74-05, AO-S1-74-5, NUDOCS 8403010486 | |
| Download: ML20086S297 (6) | |
Text
{{#Wiki_filter:-- Vinm x I A Ei.r.crn:o Axn I inn Cosmaxr To c m.t o.s n. vi n o un.s :ns:.:nt May 23, 1974 Mr. Nornan C. Moseley, Director Scrial No. 130 Diccctorate of Regulatory Operations POSM/JTB:clu i United States Atomic l'ncrgy Coa:alsalon Region II - Suite 810 Docl:et No. 50-280 230 Peachtree Street, Nortin/ast License No. DPR-32 Atinnta, Georgia 30303 Daar Mr. Moselcy: l Pursuant to Surry Power Station Technical Specification 6.G.n.1, the Virginia Electric and Power Company heraby subraits forty (40) copies of Abnormal Occurrence Report Not A0-S1-74-05. l The substance of this report has been reviewed by the Station Nuclece l Safety and Operuting Co=tittee and tilli be placed on the agenda for the next l meeting of the Systen Nuclear Safety and Operating Comaittee. Very truly yours, ,/ O'..).el'LI,4HNh.9/
- V C. M. Stallings-Vice President-Power Supply and Prt. duction Operations Enclosures 40 copics of A0-SI-74-03 m/y#"~D~?> '
\\& ~ [y ($ h, 'j'8.s i ?,\\- t cc: Mr. K. R. Galler, Assistant Director 4 'Thi for Operating Reactors e ]j (,( \\)U ' 'g 'igi4 V %\\ .l Mr. Stanley Ragone I 1/ ...~> g. i QEl b,fvQy' 6 r u l. /p / - r'- D d. + d-t: L! O b g J l'k Y []t A-8403010486 741129 / PDR ADOCK 05000280 \\ - (a _, S_ PDR.- _ ( ppyfSt2Tr RFraION j ' ~
.i. I ~ t 1 i j 4 I t i i l i i i-l l ABNOPJfAL OCCURRENCE REPORT l l, REPORT NO. A0-SI-74-05 i I t FAILURE OF CHEMICAL ADDITION VALVE MOV-CS-102B i I DOCKET No.:50-280 t LICENSE NO. DPR-32 l i 1 i i MAY 8, 1974 l l I 1 l SURRY POWER STATION i j j VIRGINIA ELECTRIC'AND POWER COMPANY. l I ~ ~ 1 t - 1 i f 4 4 .__.--_,._..____...___._..._-...._......______=.._.a__._.._.-.____..-_
I. INTRODUCTION o o in nccordance with Technical Specification 6.6 E.1 for Surry Pouer Station, Operating License Number DPR-32, this report describes an ab-normal occurrence which occurred on May 2, 1974. The Directorate of l Regulatory Operations, Region II, was notified on May 2, 1974. 1 The occurrence reported herein is classified as an abnorm. occurrence pursuant to Technical Specification 1.0.1.6 which states that "An abnormal occurrence is defined as: Engineered safeguard system malfunction or other component or system malfunction which rendered or could render the engineered safeguard system incapable of performing its intended safety function." The occurrence described herein involved the failure of chemical addition valve MOV-CS-102B to open during a periodic test. 11. SUh"1ARY OF OCCURRENCE On May 2, 1974, periodic test FT-19.1, " Refueling Water Storage Tank's Chenical Addition Tank Perforr.ance" was being conducted on Unit No. 1. At approximately 1005 hours, the chemical addition tank discharge valve, MOV-CS-102B, failed to open when operated. The parallel discharge valve, MOV-CS-102A, had previously been cycled satisfactorily. The unit was operating at 98 per cent of rated power with the unit in automatic control. The valve is a six (6) inch gate valve manuf actured by Alloyco (Alloy Steel Products Co., Inc.) manufacturer's number N-226-SP. As part of the monthly periodic test of the' chemical addition, tank, the parallel outlet motor-operated valves are exercised to verify.their operability. After isolation by manual valves, MOV-CS-102A was remotely operated from the control room satisfactorily and returned to' service. MOV-CS-102B was then tested in a. similar manner, but the valve position lights'in the contral room indicated the valve did not open. Visual observationLof valve pocition verified that the valve was.not open. D II. ' ANALYSIS Or ( L CENCE As part of the investigation of the occurrence, motor-operated valve MOV-CS-102B uas manually opened. Following the manual operation of the valve, it was satisfactorily cycled several times from the control room. After cycling, the valve was not operated for approxi-mately one (1) hour. Subsequent attempts to open the valve from the control roota were unsuccessful. During the cycling of the valve, a " popping" sound was heard when the valve was leaving its sear during opening. After verification of the proper torque and limit switch settings, the valve was disassembled and inspected. Evidence of rubbing was observed on the edge of the disc. Eeveral high spots were present on the disc where the rubbing was observed. Based on these observations, it was determined that upon scating, the valve disc had rubbed the valve body where these high spota were located and had slinhtly mis-- aligned the valve disc. The misalignment caused the valve to bind, which caused the torque switch in the motor operator circuit to de-energize the motor operator. IV. CORRECTIVE ACTION TO PREVENT RECURRENCE The corrective action was to remove the high spots from the valve disc to preclude mechanical binding of the valve when opening. The high spots were recoved, the valve re-assembled, and the proper operation of the repaired valve was verified.- The movement of the_ valve was satisfactory upon cycling several times and the " popping" noise was no longer heard. The current to the. motor operator was also checked prior to and following the repairs. Before-the.repcirs to the valve were made, the maximum load on the motor while opening was 1.2 amperes. After repairs, the maximum current was 0.95 ampere.*, f
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f) .O %d O It appears that the failure of MOV-CS-102B was due to the minor imperfections on the valve disc and no further corrective action is considered necescary. This occurrence is not related to any previous follures at Surry Power Station. V. ANALYSIS AD EVALUATION OF SAFETY IMPLICATIONS OF Tile OCCURRENCE There are two redundant, parallel motor-operated valves on the discharge of.the chemical addition tank. These valves are closed during normal unit operation to prevent mixing of the sodium hydroxide solution in the chemical addition tank with the water in the refueling water storage tank (RWST). The sodium hydroxide solution is used to remove iodinc present in the containment atmosphere during a loss-of-coolant accident and to maintain a high ph. Upon receipt of a consequence limiting cafeguards 111 -111 signal, the two oarallel chenicni addition tank discharge valves open to establish a flow path for the sodium hydroxide solution to the refueling water storage tank, and subsequently ~ to the containment spray system. The failure of MOV-CS-102B did not render the containment spray system inoperable since the redundant valve, MOV-CS-102A, opened as required to 1 establish the requisite flow path. In addition, even in the event both of the subject valves had failed.to open, redundant flow paths were still available to the containment spray system; however, the sodium hydroxide would not.have been available for-iodine removal if both valves had failed to apen. 'The spray system would have per-formed its primary function, i.e. to act as a heat sink and depressutize the containment. ~ Therefore, the containment spray system would have performed its intended function'if it had been required. ~ -
I e e VI. CONCLUSIONS The licensee concludes that: 1. The failure of MOV-CS-102B to open was caused by mechanical binding of the valve disc. 2. The corrective action described herein should prevent the recurrence of this occurrence. 3. As a result of the redundancy and demonstrated operability of the redundant motor-operated valve, there was reasonable assurance that the containment spray system would have performed as designed if it had been required. 4. The cecurrence described herein did not affect the safe operation of the Station. 5. The occurrence described herein did not adversely affect the health or anicty of the general pt:blic. l 1 .I i l I l l ~14 =}}