IR 05000206/1980009
| ML13330A059 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 04/16/1980 |
| From: | Faulkenberry B, Miller L NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| Shared Package | |
| ML13323A785 | List: |
| References | |
| 50-206-80-09, 50-206-80-9, TAC-65149, NUDOCS 8006180314 | |
| Download: ML13330A059 (12) | |
Text
.0e U. S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT
REGION V
Report N /80-09 Docket N License N DPR-13 Safeguards Group Licensee:
Southern California Edison Company 2244 Walnut Grove Avenue Rosemead, California 91770 Facility Name:
San Onofre Unit 1 Inspection at:
San Onofre Inspection conducted:
March 1 -
April 4, 1980 Inspectors:
7A
/r4/PQ (i L. Mi'Ter, ResidentTInspeKtor Date Signed Date Signed Date Signed Approved By
'
/___
_f
_
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B. H. rti1kenberry, hiefr-hfactor Projects Section #2,
'Date Signed Reactor Operation 4and Nuclear Support Branch Summary:
Inspection on March 1-April 4, 1980 (Report No. 50-206/80-09)
Areas Inspected:
Routine, resident inspection of plant operations, and follow-up on licensee event. The inspection involved 94 inspector-hours by seven NRC inspectors and management personne Results:
Of the two areas examined, two items of noncompliance were identified in the follow-up of the March 10, 1980 licensee event concerning loss of the salt water cooling system (Failure to follow emergency procedure -
Infraction, 79-09-01; Operation outside of a Limiting Condition for Operation -
Infraction, 79-09-02).
RV Form 219 (2)
8006180
.0*
DETAILS 1. Persons Contacted
- R. Dietch, Vice President, Nuclear Engineering and Operations
- L. T. Papay, Vice President, Advanced Engineering
- H. L. Ottoson, Manager, Nuclear Generation
- D. Nunn, Manager, Quality Assurance
- J. Curran, Station Manager
- R. Brunet, Unit 1 Superintendent J. Tate, Supervisor of Plant Operations (SPO)
J. Schramm, Watch Engineer J. Kroeger, Nuclear Control Operator (CO)
J. Pierson, Nuclear Assistant Control Operator (ACO)
P. Imbach, Nuclear Assistant Control Operator (ACO)
R. Waller, Nuclear Plant Equipment Operator (PEO)
V. Salvatore, Nuclear Engineer G. Beetz, Maintenance Supervisor
- K. P. Baskin, Manager, Nuclear Engineering and Licensing The inspector also interviewed other licensee employees during the inspectio *Denotes those attending the Exit Interview on April 3, 1980. NRC Region V Personnel attending the April 3, 1980 Exit Interview included the following:
R. H. Engelken, Director, Region V, Office of Inspection and Enforcement J. L. Crews, Chief, Reactor Operations and Nuclear Support Branch, Region V B. H. Faulkenberry, Chief, Reactor Projects Section 2, Reactor Operations and Nuclear Support Branch, Region V A. D. Johnson, Enforcement Coordinator, Region V L. F. Miller, Resident Inspector, San Onofre Unit 1 A. J. Horn, Reactor Inspector 2. Loss of Salt Water Cooling.System Event of March 10-11, 1980 At 9:30 a.m. on March 11, 1980, the resident inspector at San Onofre Unit 1 was verbally informed by the Unit Superintendent that the Unit had exper ienced a loss of salt water cooling event on March 10, 1980, which the licensee considered to be prompt reportable under Technical Specification 6.9.2.a. The inspector reviewed the Generating Station Log of this event early that after noon and immediately telephoned a preliminary description of the event to the Region V office. Discussions of the event were held between the inspector and various licensee operating and supervisory personne These discussions cul minated in formal interviews of all operating personnel on shift at the time of the event, and their supervisors, by the resident inspector and a regional investigator, Mr. 0. Shackleton, on March 14-15, 1980. As a result of that investigation, a reconstruction of the event was produced (Paragraph 3).
-2 At 9:15 p.m., on March 10, 1980, the shaft on the in-service south salt water cooling pump sheared, rendering it inoperable. The north salt water cooling pump automatically started, but its discharge valve, which should have opened automatically when the pump started, did not open. This pump was therefore also inoperable at 9:15 p.m. The Control Operator (CO) manually started the auxiliary salt water (ASW) cooling pump from the control room at 9:20 p.m., but at 9:25 p.m. both he and the Watch Engineer (WE) were made aware by the Assistant Control Operator (ACO) that this pump was not provid ing coolant flow. At about that time, the WE and a Plant Equipment Operator (PEO) cross connected the discharge salt water flow from the screen wash pumps to the discharge piping at the north salt water cooling pump. This connection provided sufficient cooling to the bottom component cooling water heat exchanger to stop the rapidly rising component cooling water temperature at 82 degrees F and return temperature to a new equilibrium valve, 70 degrees F, some four degrees above its value at the beginning of the event. (These fi gures are based on the records of component cooling water temperature, TR-606, assuming the event began at 9:15 p.m., with a chart scale factor of.76 inch/
hour.)
At 9:56 p.m. on the third start of the ASW pump by control room operators, the ASW pump spontaneously started pumping to the top component cooling water heat exchanger which was not receiving component cooling water flow at the tim Thus, the starting of this pump had no immediate effect on component cooling water temperatures. At 10:00 p.m., at the direction of the WE, a load reduc tion from full power, in anticipation of a unit shutdown, was begun and immediately stopped after a reduction of 2-3 MW in unit load from full powe The WE countermanded his earlier order after discussions with the Supervisor of Plant Operations (SPO).
At about 10:13 p.m., the top component cooling water heat exchanger was placed in service. At this time, the WE and Unit Superintendent authorized a Plant Change Notice (PCN) to the emergency pro cedure, S-3-5.34, "Loss of Salt Water Cooling to the Component Cooling System,"
which had been in effect since 9:15 p.m. As discussed below, the PCN dimin ished the actions required by the licensed operators upon loss of salt water cooling. At 12:05 a.m. on March 11, 1980, the discharge valve on the north salt water cooling pump was opened locally by maintenance personnel and the north salt water pump became operable. This concluded the event. The unit was maintained at or near full power throughout the even The most abnormal temperatures reached by a component cooled by component cooling water were on the thrust bearing on the south charging pump. This bearing had not generally exceeded 138 degrees F until January 26, 198 At the time this event began, it was operating at 170 degrees F, however, during the event it rose to 178 degrees F. The manufacturer of the pump recommends that the oil leaving the bearings not exceed 160 degrees F, and the licensee believes that the direct contact reading of 178 degrees F on the thrust bearing did not correspond to an oil temperature leaving the thrust bearing greater than 160 degrees F. Nevertheless, after the event of March 10, 1980, the thrust bearing was found to be unserviceable and was replace Subsequent to the event, automatic features of the salt water cooling system continued to be unreliable. For example, on March 24, 1980, the discharge valves on both north and south salt water cooling pumps were being maintained open, overriding the automatic controls, with both salt water cooling pumps running, because of unsatisfactory operability checks of these valves on March 22-23, 1980. The failure of both automatic systems to operate, as well as the backup manual auxiliary system, demon strated inadequacy in at least this system's surveillance progra The licensee has agreed to review its surveillance and maintenance programs for safety related equipment to verify their adequacy in assuring system availability. The completed review will be inspected by the resident inspector (01 80-09-03).
The operation of the unit duing this event was not in accordance with the Code of Federal Regulations 10 CFR 50 and the Technical Specifications in two respects:
a. Technical Specification 6.8.1 requires, in part, that written procedures shall be established, implemented and maintained that meet or exceed the recommendations of Appendix 'A'
of USNRC Regulatory Guide 1.33, Quality Assurance Program Requirements (Operations), and Sections and 5.3 of ANSI 17.7-1976, Administrative Controls for Nuclear Power Plant ANSI N18.7-1976, Section 5.3, Preparation of Instructions and Procedures, requires that "activities affecting safety at nuclear power plants be described by written procedures of a type appropriate to the circum stances and shall be accomplished in accordance with these instructions and procedures." In particular, Section 5.3.9 states that when immediate operator actions are required to prevent or mitigate the consequences of a serious condition, procedures shall require that those actions be implemented promptl On March 10, 1980, when this event began, Emergency Operating Instruction S-3-5.34, Rev. 0, "Loss of Salt Water Cooling to the Component Cooling System," required that if both north and south water cooling pumps were inoperable, and if the auxiliary salt water cooling pump flow'was inadequate, the unit should be trippe Contrary to this requirement, the unit was not tripped as required by the procedure. This is an infraction (80-09-01).
b. Technical Specification 3.3.lA(l)h requires that the reactor shall not be maintained critical unless either:
-4 (1) Two salt water cooling pumps are operable (i.e., the north and the south), in which case Technical Specification 3.3.lB(6)
allows maintenance to be performed on either the north or the south pump for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> while critical provided that the other pump (north or south) is tested first to demonstrate its availability; or (2) The auxiliary salt water pump and either the north or the south salt water pump are operable, in which case, Technical Specifica tion 3.3.1B(6) allows maintenance to be performed on the auxiliary pump for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> while critical provided that the remaining north or south salt water pump in service is tested first to demonstrate its availabilit The Technical Specification does not permit the north and the south salt water cooling pumps to be simultaneously inoperable with the reactor critical, with or without an operable auxiliary salt water cooling pump. Although the auxiliary pump has comparable pumping capacity, it does not automatically start and line-up salt water and component cooling water to the component cooling water heat exchangers under accident conditions with loss of offsite power, asdo the north and south salt water cooling pumps and associated valves and interlock Contrary to the Technical Specifications cited,on March 10, 1980, from about 9:15 p.m. until 9:56 p.m., the reactor was operated at or near full power with neither north, south, nor auxiliary salt water cooling pumps operabl In addition, and contrary to the Technical Specifications cited, on March 1-11, 1980, from about 9:56 p.m. until 12:05 a.m., the reactor was operated at or near full power with only the auxiliary saltwater cooling pumps operabl During both periods of time, reactor operation was continued after a condition more limiting than the most limiting operating condition permited by the Limiting Condition of Operation of the Technical Specifications was encountered. The total period of such operation was about two hours and fifty minutes. This is an infraction (80-09-02).
3. Detailed Chronology of Salt Water Cooling Events of March 10-11, 1980 Time Comments Monday,
"Salt Water Cooling Pump Discharge Low Pressure" alarm March 10, 1980 and "Loss of Salt Water Cooling Flow" alarm received and noticed by CO, ACO, WE, PEO and #4 (RCP) ma.0-5 Time Comments North Salt Water Cooling pump (NSW) automatically starts, discharge valve for the South Salt Water cooling pump (POV-6) shuts, discharge valve for the North Salt Water cooling pump (POV-5) should have opened, but did not ope Component Cooling Water (CCW) to Bottom (or North) CCW Hx Heat Exchanger (Hx) automatically initiated, in parallel with existing flow to Top (or South) CCW Hx, which was in service along with South Salt Water Cooling pump (SSW) at the time of initiatio Control room (CR) operators observed about 37 amps for SSW pump, an abnormally low reading, and an abnormally low and erratic reading for the NSW pum WE and PLO went to the NSW pump, ACO rushes to the CCW Hx's to check for piping integrity, at CO's direction. CO and
- 4 (RCP) man remain in CR. PEO is told by CO to check that NSW pump is running properl CR operators notice CCW temp rising "slowly." WE tells CO that he was going to evaluate situation, but gives CO no specific direction :15-9:20 PEO and WE arrive at SNW and SSW pumps. They notice that the NSW pump and the SSW pumps are both running against shut discharge valves. The PEO recalls that the NSW pump discharge pressure was about 44 ps These two inform the CR of this status of the pumps. The PEO tries several different methods of sending control air to the NSW pump POV using the valves called "star wheels" to open the NSW pump POV, with no succes :20 CR Operators start the Auxiliary Salt Water cooling pump (ASW).
(This pump is physically about 40 yards from the NSW and SSW pumps, which are located in the same general area of the plant. The CCW Hx's are about 75 yards away from any of these pumps and it is only at the CCW Hx's that any salt water cooling flow to the Hx's can be read.)
They observe a pump running current which is approximately 50% of normal value, and the WE, who is still at the NSW and SSW pumps, is informed. He is also informed by the CR that CCW temperatures are coming up slowly after he in quires about the Time-Comments 9:25 WE moves to ASW pump, leaving PEO with directions to continue trying to open NSW pump PO The WE observes that the ASW pump is running but "it did not sound as if it was pumping water."
He recalled seeing about 18" of vacuum on the priming tank, a normal value. He was aware of three indications that the pump was not running:
no flow on the flowmeter at CCW Hx, no sound of water from the pump, and low pump running amperage in the C (Note:
CCW flow and ASW pump amerage are observed in the CR, therefore the WE must have received phone or radio reports on these parameters.)
ACO reports to CR that the CCW Hx's do not indicate salt water cooling flow is present, that the ASW pump dis charge valve is open, and that the piping in the area appears intac CR operators break out the emergency procedure for loss of salt water cooling, S-3-5.34. CR operators inform WE that ASW pump is running, and cycle the ASW pump OFF-ON-OFF, but no normal pump running current is obser ved. CCW temperatures are observed to be rising, but the rate of rise is not alarmin PEO reports no success opening North PO :28 WE tells CR operator to stop SSW pump, which has been running at shutoff since the automatic start of the NSW pum :30 p.m.*
WE decides to cross-connect the Screen Wash pump discharge to the NSW pump discharge with the PEO's assistance, and informs the CR of his decision. This is accomplished and both Screen Wash pumps are starte The PEO recalls seeing 25 psi on the NSW pump discharge line to the Bottom (North) CCW H CR operators observe unspecified CCW system temperature to peak at 82 degrees F, 16 degrees above normal and 15 degrees below the alarm set point, and then to decrease to 70 degrees F by 9:45 p.m. This reduction was surpris ing to CO, WE, and #4 man, all of whom independently
- Based on the CCW temperature recorder Chart, TR-606, using a.76 inch/hour scale factor, this event occurred at 9:26 p.m. This scale factor was derived using three times marked on the recorder:
9:15 p.m., March 10, 5:47 and 7:32 a.m. on March 11, 198 Time Comments commented that the sufficiency of this mode of salt water cooling was untested and unproven at full power operatio ACO reports to CR that about 1800-2000 gpm salt water flow to Bottom (North) CCW HX exists no :30-9:35 WE returns to CR, leaving PEO to continue trying to open NSW discharge valv WE, once in CR, directs #4 (RCP) man to leave CR and proceed to NSW pump to assist PEO because #4 (RCP)
man has greater experience with hard-to-open pneumatically operated valves (POVs) (several operators comment that that the SSW discharge POV had recently been difficult to open without operator manual intervention, as well as historically, other POVs in the plant).
The #4 (RCP)
man understands, in leaving, that the WE will "watch the (RCP) pumps."
At this point, the operators in the CR are the CO and the W The #4 (RCP) man arrives at the NSW pump POV and tries a variety of methods to open it (all unsuccessful). He dispatches the POE to the ASW pump to check it. The PEO recalls that he found the ASW pump not running, but lined up satisfactorily (including the priming system).
9:40-9:45 CCW temperature has apparently decreased to 70 degrees F with the Screen Wash pumps providing cooling to Bottom (North) CCW H (Forms for plant shutdown were brought out sometime after 2130.)
CR cycles the NSW pump ON and OFF, but receives no indication of flow from pump running current indication The thought was that this cycling might open the NSW discharge POV, which it did not d WE talks to CO and they agree not to trip the reactor, at this time. They both recognize that the emergency procedure calls for a reactor trip, but believe that the presence of salt water cooling from the screen wash pumps makes an immediate trip inappropriat Time
-..
Comments 9:45 SSW pump is turned ON, then OFF, causing MOV-720A, the discharge valve on the TOP (South) CCW Hx to open, CCW to bypass the operable CCW Hx momentarily until operators shut MOV-720A. (Seen on TR-606 chart).
9:50 WE calls SPO and explains conditions. SPO was asleep and understood that plant condition was stable, maintenance men were being called to repair the NSW discharge POV, and that the situation was under contro He did not recall the details, not being fully awake before taking the cal About 9:55 First ACO returns to CR and becomes #4 (RCP) man, in place of the previous #4 (RCP) man who had left. He overhears WE and CO deciding to inform dispatcher that unit "may have to be shut down."
9:56 CR restarts ASW pump for third time and observes normal pump running curren The original #4 (RCP) man observes ASW pump to be running normally, and he rattles drain trip in priming line; he then goes to the salt water flow guage and observes 3900 gpm salt water cooling flow to the Top (South) CCW H WE tells CO to "take a load drop," then calls SPO a second time and redescribes the event sequencing to him, and tells him that he will start a shutdown. SPO tells him NOT to start a shutdown because with the ASW pump operable, the TS would allow 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> before a shutdown was require CO contacts the dispatcher to inform him of the possibility of a shutdow :00 CO directs ACO to start reducing loa PEO returns to CR as ACO is beginning power reduction and observes a 2-3 MW power reductio WE asks whether load is being reduced, finds that it is, and orders "Hold the load drop."
Power reduction is stoppe Time Comments 10:00-10:05 WE makes succession of phone calls. Three calls are necessary to call a mechanic to repair the POV. Then the Unit Superintendent is called and given a detailed summary of the event. S-3-5.34 is discussed and they agree on a Plant Change Notice (PCN) which deletes the requirement to trip the unit if all SW pumps become in operable and adds the requirement to take the unit off line "in a controlled manner."
The PCN also states that if one pump remains operable to shutdown the unit with 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, instead of immediately. The reason given on the PCN for this change is that "the Screen Wash system has been determined to maintain adequate system tempera ture."
The WE prepares the PCN upon instructions from the SUPT, but the SUPT stated that he does not read the text of the PCN until the following morning when he directs that the words "and go subscritical" be added after "take the unit off line in a controlled manner."
10:10 NSW pump is stopped by C :17 Top (South) CCW Hx, which has been receiving salt water from the ASW pump since 2156, is placed in service.*
10:15-10:20 SUPT calls Station Manager (SW) and they discuss the situatio Generating Station Log states that Bottom (North) CCW Hx is taken out of service and the Screen Wash water cross connect to it was secured. (Consistent with recorder reconstruction.) Review of Plant Operations The inspector reviewed various shift logs and operating records, including data sheets, instrument traces and records of equipment malfunction. Cogni zance of significant plant operations was maintained by the inspecto No significant changes or trends in plant operations or plant parameters affecting the safe operation of the facility were observed. The following specific areas were included in this revie *Based on reconstructed time from CCW temperature recorder chart, TR-60 a. Control Room logs were observed to be filled out for the period of this report. Abnormal conditions were identified by the operating staff in their logs, and resolution of these conditions was under way or complete Specific abnormal conditions noted by the inspector during the inspection included:
(1) High reactor coolant pump 'C' seal leakoff flow indication. (This condition was also noted in Inspection Report 80-02, but the licensee has been unable to diagnose and correct it to date in spite of some attempts to do so (01 80-09-04).
(2) Rupture disc of the pressurizer relief tank was blown out due to an operator erro (3) Some instruments in the auxiliary control panel were observed to be'out of service. Discussions with NRR revealed that at present this was acceptable. Similiarly, the requirement to have the 12 KV tie line to the No. 3 480V bus operable was discussed with plant personnel..These discussions are still in progress (01 80-09-05).
b. The Generating Station and Watch Engineer's Logs for the period of this report provided sufficient detail to communicate equipment status, test ing of redundant components, clearances, permissions, and approval c. Tours of accessible areas were performed periodically by the inspector in order to independently assess equipment and plant conditions. Speci fically, the following.areas were reviewed:
(1) Monitoring recorders were operable and did not indicate any Technical Specification violations, except as discussed in Paragraphs 2 and (2) Radiation controls appeared to be properly established. It was observed that the roped-off radiation control areas were properly posted for the indicated radiation levels. Step-off pads and protective clothing disposal containers were adequat (3) Flammable materials were not observed to be stored inside or adjacent to safety related buildings or systems, although con siderable amounts of treated fire-resistant wood were present in both the 4KV switchgear room and the lube oil storage area to provide scaffolding for the installationof plant modification The general level of cleanliness was acceptable, with evidence of continuing effort by the licensee to keep work areas reasonably clea (4) No gross piping vfibrations were observe (5) The inspector traced the piping and valves in the Salt Water Cooling system. No lineup errors were note (6) Two licensed operators were observed to be present in the control room. One of the operators was always observed to be "at the controls."
5. Exit Interview An exit interview (Paragraph 1) was held on April 3, 1980, to summarize the scope and findings of this inspection. This interview was held with senior representatives of the Southern California Edison Company.to review the facts of the March 10, 1980 loss of salt water cooling event. The licensee's commit ments at this meeting were confirmed in an Immediate Action Letter to the licensee from the regional office on April 4, 1980.