ML19344B159
| ML19344B159 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 07/25/1980 |
| From: | Frank L ENERGY, DEPT. OF |
| To: | Goodwin C PORTLAND GENERAL ELECTRIC CO. |
| References | |
| NUDOCS 8008250668 | |
| Download: ML19344B159 (4) | |
Text
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Department of Energy v' cgs" LABOR & INDUSTRIES BUILDING, ROOM 102. SALEM, OREGON 97310 PHONE 378-4040 July 25, 1980 Q
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Charles Goodwin, Jr.
Assistant Vice President Portland General Electric Company 121 SW Salmon Street Portland, OR 97204
Dear Mr. Goodwin:
The purpose of this letter is 1) to request furtiler PGE corrective actions to prevent recurrence of three recent reportable occurrences and
- 2) to request PGE to re-evaluate the approach to reviewing reportable occurrences and take actions to provide for a timely, in-depth, independent review.
Background
On April 22, 1980, PGE issued Licensee Event Report 80-05 concerning f ailure of three main steam isolation valves to close upon testing. The cause of this event was binding between the valve stem and packing. As corrective action, the packing was modified.
On June 20, 1980, PGE issued Licensee Event Report 80-09 concerning a situation where the water level of the spent fuel pool was lowered below the minimum level required by License Technical Specifications. The cause of this event was operator error compounded by failure of the low l
level alarm. As corrective action, all operators were informed of this event, a caution statement was added to the procedure for draining the l
refueling cavity, the low level alarm was repaired, and the frequency of the functional test of this alarm was changed from once per refueling outage to once per six months.
On June 27, 1980, PGE issued Licensee Event Report 80-10 concerning a situation where the baron concentration of the reactor coolant system was below the minimum requireo by License Technical Specifications. The i
cause of this event was procedural inadequacy in that the procedure for cleaning the steam generator divider plates was not consistent with applicable License Technical Specifications. As corrective action, the procedure has been corrected.
8008250 ddf b
Charles Goodwin, Jr.
July 25, 1980 Page 2 000E Comments Although none of these events had an adycrse impact upon public health and safety, it is imperative that actions Le taken to prevent recurrence of these events or similar events due to the potential for affecting public health and safety. ODOE does not believe that adequate corrective actions have been identified and taken in these instances to prevent such recurrence.
In the first event, the failure of the valves to close would have resulted in steam line blowdown in excess of that assumed in the accident analysis for a concurrent steam line rupture. Two of the valves also f ailed to close in 1979 and the corrective action identified then involved minor changes to the packing. Since this corrective action was demonstrated to be inadequate, in April 000E verbally enccuraged PGE to take more positive corrective actions this time, such as modifying the existing air cylinder to assist in closing.
Instead of modifying the air c,linder, PGE implemented corrective actions involving further minor chaiqes to the packing.
During the recent startup, the valve packings were discovered to leak.
Upon tightening, the valve stems bound preventing complete closure.
Therefore, PGE has elected to operate with the packing leaks. 000E understands that PGE is reviewing this problem to identify appropriate further actions. ODOE hae. the following comments on further actions:
1.
000E is concerned about the ability of the valves to close upon initiation signal. PGE has stated that although the valves have failed to close during testing without steam flow the valves would have closed in the presence of the steam flow associated with a concurrent steam line rupture. ODOE considers one of the following approaches should be taken:
a.
PGE should orovide conclusive test data or calculations that support the statement that the valves will close in the presence of steam flow, including both a changing dynamic flow situation and a transition from a static to a dynamic situation that might occur during a steam line rupture.
If such a statement is supported, identify and implement a periodic test that will verify that the valves will indeed close in the presence of steam flow.-
b.
If the statement that the valves will close in the presence of steam flow cannot be supported or a periodic test to verify this l
l is unacceptable (e.g. due to induced plant transients), take l
actions to ensure valve closure upon initiation signal l
regardless of flow situation, such as modifying the existing air l
cylinder to assist in closing, i
i t
Charles Goodwin, Jr.
July 25, 1980 Page 3 2.
PGE is requested to identify the radiological consequences of continued operation with packing leaks considering concurrent fuel clad f ailures and steam generator tube leaks since the packing leaks are outside the containment and turbine buildings and are therefore not monitored by existing radiation instruments. Based on the identified consequences, PGE is requested to take appropriate actions to provide for radiological monitoring and control. Also, sirce it is not good engineering practice to operate with steam leaks since they typically get worse, may damage equipment, and are a personnel hazard, 000E encourages PGE to act quickly to eliminate the packing leaks.
In the second event, if the operator had not noticed the low water level, the level could have decreased to within about two feet of the top of the spent fuel. This may be adequate for cooling but would have resulted in high radiation levels in the area. The location of the nearest area radiation monitor and associated geometry effects might permit high radiation levels at the spent.uel pool surface prior to activating the radiation alarm. Therefore, 000E considers it important that the low level alarm be functional. Changing the periodicity of the functional check from about once per year to twice per year does not provide the necessary assurance. This is demonstrated by the f act that the alarm was tested and determined to be functional about one month prior to this event. To achieve the necessary assurance, 000E considers installation of another, independent low level alarm in conjunction with more frequent functional tests would be appropriate.
In addition, PGE should evaluate whether the level alarms should be safety grade instruments.
In the third event, the particular cleaning procedure apparently would have permitted dilution of the boron concentration such that the reactor was calculated to be only 1 percent subcritictl. Since the reactor had recently been reloaded and core physics testing had not yet been performed, this is not adequate margin to account for reactivity uncertainties. Therefore, the License Technical Specifications require the reactor to be at least five percent subcritical during the refueling l
mode. As stated above, this particular procedure has been corrected.
l However, ODOE does not consider that this is a complete corrective action to prevent recurrence.
Since the cause of this event was that a procedure was not consistent with the License Technical Specifications, PGE is requested to conduct a detailed review of ell plant procedures to ensure this req'uired consistency exists.
l One further action that warrants consideration to prevent recurrence of this event or similar events involving boron concentrations is the installation and use of an on-line boron analyz?r in the letdown line of the reactor coolant system as used in mera recent pressurized water reactors. This analyzer provides continuous monitoring of boron concentration rather than relying on periodic chemical analysis as Trojan does. Such an analyzer may also provide operational benefits.
Therefore, PGE is requested to evaluate installation and use of such an analyzer.
l
Charles Goodwin, Jr.
~
July 25, 1980 Page 4 During 000E's review of Licensee Event Reports, it has become apparent that typically only individuals responsible for plant operation review reportable occurrences.and identify corrective actions prior to issuance of the Licensee Event Report. The Nuclear Operations Board, which consists of individuals from PGE corpoiate headquarters, is charged with conducting an independent review and atdit of various plant activities, including reportable occurrences. However, it is OD0E's impression that these reviews are infrequent, usually occur several months af ter the reportable occurrence, and are cursory in nature. As a possible solution, PGE engineers in corporate headquarters could be involved in reportable occurrence evaluations to provide an in-depth independent review prior to issuance of Licensee Event Reports by individuals who have some responsibility for plant safety but no operational responsibility. This approach would provide additional assurance that appropriate corrective actions have been identified and taken to prevent recurrence.
Request for Actions PGE is requested to take the following actions:
1.
Re-evaluate the three subject Licensee Event Reports and take appropriate actions to prevent recurrence of these and similar events. Within 30 days of receipt of this letter, submit to 000E the results of the re-evaluations and actions taken.
2.
Re-evaluate PGE's approach to reviewing reportable occurrences and, if appropriate, take actions to provide for an in-depth independent review of these prior to issuance of Licensee E!ent Reports. Within 60 days of receipt of this letter, submit to 0 DOE the results of the re-evaluation and actions taken.
Si cere1xy v'
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Lynn/ rank F
Director LF/BD:swd 8438A R 3-14-10 Charle's Trammell, NRC, ORB 3 cc:
Robert Engelken, NRC, Region V Ed Whelan, PGE r
p y