United States Nuclear Regulatory Commission - Protecting People and the Environment

Referencing 6/29/79 Letter Re Multiple Equipment Failures (Generic Letter 79-44)


GL79044 

                              UNITED STATES 
                      NUCLEAR REGULATORY COMMISSION 
                          WASHINGTON, D. C. 20555 

                           September 21, 1979  

ALL PRESSURIZED WATER REACTORS  

Gentlemen: 

The enclosed letter dated June 26, 1979 regarding multiple equipment 
failures and surveillance testing errors was sent to all pressurized water 
reactors. However, due to distribution problems, the letters were delayed 
and apparently not all licensees have received their copy. 

To ensure that all licensees are in receipt of the June 26, 1979 letter, a 
copy is being transmitted with this letter, in addition to a copy of the 
July 16, 1979 Office of Inspection and Enforcement inspection report 
pertaining to the events referred to in the letter. 

Within 30 days of receipt of this letter, you are requested to provide the 
results of the reviews discussed in the June 26, 1979 letter. 

                                   Sincerely, 


                                   Darrell G. Eisenhut, Acting Director 
                                   Division of Operating Reactors 
                                   Office of Nuclear Reactor Regulation 

Enclosures: 
As Stated 

                                                                 7910230561 
.

                               UNITED STATES 
                       NUCLEAR REGULATORY COMMISSION 
                         WASHINGTON, D. C.  20555 

                               June 26, 1979 

ALL PRESSURIZED WATER REACTORS 

Gentlemen: 

Recently, because of operator error, an inadvertent reactor scram and safety
injection occurred during monthly surveillance tests of the safeguards 
system at a PWR facility. 

At the time of the event, train "A" of the safeguards system had been placed
in "test", and the operator, in addition to inserting a high steam flow 
signal required by the test, inadvertently incorrectly inserted a low steam 
pressure signal. This action resulted in a low steam pressure signal 
(signifying a main steam line break) in train "A" which initiated main steam
isolation valve (MSIV) isolation and a reactor scram. One MSIV, however, did
not close because of a valve solenoid failure. The resultant differential 
pressure between two steam lines initiated a safety injection signal from 
train "B". In the ensuing events several more equipment failures occurred. 
One feedwater regulation valve failed to close because of another solenoid 
failure. The steam driven auxiliary feedwater pump tripped on overspeed and 
one of the steam generator atmospheric relief valves failed to fully reseat 
upon closure. 

This occurrence, with its ensuing sequence of events, is of concern to the 
NRC staff because of the serious questions that are raised due to the 
multiple equipment failures and whether a very real problem could exist that
has not been analyzed. For example, the potential for common mode failures 
(in this case two apparently independent solenoid valve failures) should be 
investigated to ensure that a problem does not exist which could negate the 
criteria assumed in your previous accident analyses or which could lead to 
an overall reduction in system reliability. 

This occurrence is also of concern because of an apparent sense of 
complacency towards periodic surveillance requirements in general and on 
engineered safeguards systems in particular which has all too often resulted
in inadvertent reactor scrams and safety injection system actuations. From 
the standpoint of unnecessary challenges to the reactor trip and the 
safeguards systems and the imposition of unnecessary thermal stress cycles 
on reactor coolant system and its components, this is undesirable. 
.

                                  - 2 -                     June 26, 1979 

You and your plant supervisors should review the events described in this 
letter, to determine whether similar errors have occurred or could occur at 
your facility and whether the potential exists for a problem associated with
occurrences that you have not previously considered. 

In addition, it is requested that management policies and procedures be 
reviewed and strengthened as necessary to assure that multiple equipment 
failures in safety-related systems will be vigorously pursued and analyzed 
to identify potential failure modes not previously considered that could 
lead to a significant reduction in the ability of safety systems to function 
as required. Finally, you are requested to review your engineered safety 
system surveillance procedures to determine whether appropriate cautions are
included and to ensure that plant operators and supervisors are aware of the
importance of avoiding challenges to the protective features of your 
facility. 

Within 30 days of receipt of this letter, please submit, in accordance with 
10 CFR SS 50.54(f) of the Commission's regulations, the results of these 
reviews. In addition to licensing reviews of these matters, we have 
requested that the NRC's Office of Inspection and Enforcement perform a 
followup inspection on these matters in the near future. 

                                   Sincerely,  


                                   Darrell G. Eisenhut, Acting Director  
                                   Division of Operating Reactors 
                                   Office of Nuclear Reactor Regulation 
.

                               UNITED STATES 
                      NUCLEAR REGULATORY COMMISSION 
                                REGION III 
                            799 ROOSEVELT ROAD 
                        GLEN ELLYN, ILLINOIS 60137 

                                JUL 16 1979 

Docket No. 50-295 
Docket No. 50-304 

Commonwealth Edison Company 
ATTN:     Mr. Byron Lee, Jr.
          Vice President 
Post Office Box 767 
Chicago, IL 60690 

Gentlemen: 

This refers to the inspection conducted by Mr. J. E. Kohler of this office 
on April 28 through June 1, 1979, of activities at Zion Nuclear Power 
Station, Units 1 and 2, authorized by NRC Operating License No. DPR-39 and 
No. DPR-48 and to the discussion of our findings with Mr. N. E. Wandke at 
the conclusion of the inspection. 

The enclosed copy of our inspection report identifies areas, examined during
the inspection. Within these areas, the inspection consisted of a selective 
examination of procedures and representative records, observations, and 
interviews with personnel. 

No items of noncompliance with NRC requirements were identified during the 
course of this inspection. 

In accordance with Section 2.790 of the NRC's "Rules of Practice," Part 2, 
Title 10, Code of Federal Regulations, a copy of this letter and the 
enclosed inspection report will be placed in the NRC's Public Document Room, 
except as follows. If this report contains information that you or your 
contractors believe to be proprietary, you must apply in writing to this 
office, within twenty days of your receipt of this letter, to withhold such 
information from public disclosure. The application must include a full 
statement of the reasons for which the information is considered  
proprietary, and should be prepared so that proprietary information 
identified in the application is contained in an enclosure to the 
application, 
.

Commonwealth Edison Company      - 2 - 

We will gladly discuss any questions you have concerning this inspection. 

                                        Sincerely, 


                                        R. F. Heishman, Chief 
                                        Reactor Operations and 
                                        Nuclear Support Branch 

Enclosure: IE Inspection 
     Reports No. 50-295/79-13 
     and No. 50-304/79-12 
.

                    U.S. NUCLEAR REGULATORY COMMISSION 
                   OFFICE OF INSPECTION AND ENFORCEMENT 

                                REGION III 

Report No. 50-297,/79-13; 50-304/79-12 

Docket No. 50-295; 50-304                       License No. DPR-39; DPR-48 

Licensee: Commonwealth Edison Company 
          Post Office Box 767 
          Chicago, IL 60690 

Facility Name: Zion Nuclear Power Station, Units 1 and 2 

Inspection At: Zion Site, Zion, IL 

Inspection Conducted: April 28 through June 1, 1979 


Inspector:     J. E. Kohler                                      7/13/79   

Approved By:   F. L. Spessard, Chief                             7/13/79   
               Reactor Projects Section 1  

Inspection Summary 

Inspection on April 28 through June 1, 1979, (Report No. 50-295/79-13; 
50-304/79-12) 

Areas Inspected: Routine inspection of plant operations, maintenance, 
non-routine events occurring during the inspection, quality assurance audit 
results, plant cleanliness, and spent fuel pool modification activities. The
inspection involved 144 hours of onsite inspection by one NRC inspector. 

Results: No items of noncompliance were identified. 
.

                                DETAILS 

1.   Persons Contacted 

      N. Wandke, Plant Superintendent 
     *C. Schumann, Operating Assistant Superintendent 
     *T. Parker, Assistant Technical Staff Supervisor 
     *B. Ward, Unit 2 Operating Engineer 
      E. Fuerst, Unit 1 Operating Engineer 
     *B. Harl, Quality Assurance 
      J. Joosten, Primary Group Leader Tech Staff 
      K. Schultz, Training Supervisor 
      F. Resick, Station Health Physicist 
      R. Landrum, Nuclear Station Operator 
      T. Flowers, Shift Engineer 
      N. Valos, Shift Foreman 
      F. Pauli, Shift Engineer 
      L. Pruett, Shift Foreman 
      D. Ray, B Operator 
      J. Johnson, B Operator 
      T. White, Instrument Mechanic 
      D. Kaley, Nuclear Station Operator 
      E. Murach, Maintenance Assistant Superintendent 
      L. Soth, Administration and Support Assistant Superintendent 
      G. Armstrong, Shift Engineer 
      N. Loucas, Shift Foreman 
      D. Walden, Fuel Handling Foreman 
      J. Lafontaine, Fuel Handling Foreman 
      P. Kuhner, Quality Control 

     *Denotes those present at the exit interview. 

2.   Safety Injection Unit 23 1979 (LER 50-295/79-42) 

     At approximately 1:45 on May 23, 1979 with Unit 1 at 100% power a 
     safety injection occurred during performance of periodic test procedure 
     PT 10a and b, the monthly safeguards logic test. The safety injection 
     resulted in main steam isolation valve closure and full secondary steam 
     relief. No structural damage or water hammers occurred. The injection 
     lasted for approximately three minutes during which time the licensee 
     personnel monitored containment pressure and temperature, primary 
     system pressure, pressurizer level and steam generator levels. Shift 
     personnel determined that the safety injection was inadverent not 
     resulting from a steam line break, and terminated the safety injection. 
     Confirmation that steam line break indication did not exist on plant 
     instrumentation was obtained by the NRC resident inspector. 
     
                                   - 2 -
.

     The cause of the safety injection was attributed to personnel error and
     failure of the B main steam isolation valve to close from safety 
     injection Train A. The procedure (PT 10a and b) calls for developing 
     the logic for high steamline flow and requires depressing a pushbutton 
     labeled RT which is located in the auxiliary electrical area. The RT 
     pushbutton is depressed while Train A safeguards logic is in test. 
     While depressing the RT pushbutton, two pages of the procedure were 
     inadvertently skipped and pushbuttons which yielded a low steamline 
     pressure were depressed simultaneously with the RT pushbutton. This 
     action developed a safety injection logic for Train A (high steamline 
     flow concident with low steamline pressure signifying a steamline 
     break). 
     
     Although Safeguards Train A was in test, valve positioning resulting 
     from the signals is not inhibited. For steamline break protection, main
     steam isolation valves A, B, C and D receive the closure signal from 
     Train A. The A, C, and D MSIVs closed as designed while the B MSIV 
     failed to close from Train A. Failure of the B MSIV to close caused a 
     Train B safeguards actuation from the 100 pound differential pressure 
     safety injection. 

     Several discrepancies were noted during and after the safety injection 
     resulting from Train B. These discrepancies are described in the 
     following table along with the corrective action and the safety 
     significance. 

Equipment      Failure        Corrective Action        Safety Significance 

B MSIV         Failed to      Pilot valve replaced,    Would have closed 
(LER           close from     retested by PT-23        automatically from 
No. 79-40)     Train A        successfully.            Train B if real 
                                                       steamline break 
                                                       existed. Closed 
                                                       manually from the 
                                                       control room. 

Feedwater      Failed to      Solenoid was cleaned,    Closed Automatically 
Reg. Valve     close from     repaired and retested    from Train B. 
1B (DVR        Train A        by depressing relays 
No. 1-79-73)                  F4, and F5. 

Main steam     Partially      Manually reset           Each steamline has
Safety         opened and     by prying to full        five steam safety
Valves         failed to      open position.           valves capable of
               reset.                                  passing 110% of rated
                                                       steamflow at 110% 
                                                       steam generator 
                                                       pressure. No 
                                                       excessive cooldown 
                                                       occurred. 

                                   - 3 -
.

Equipment     Failure        Corrective Action        Safety Significance 

Turbine        Started        Adjusted governor,       The plant has two
Driven         but steam      performed periodic       electric driven and
Auxiliary      supply         surveillance test        one turbine driven
Feedwater      valve          successfully.            auxiliary feedwater
Pump 1A        tripped                                 pumps. Only one of
(DVR No.       closed.                                 three is necessary 
1-79-72)                                               for safe shutdown.
                                                       Technical 
                                                       Specifications 
                                                       requirement for two 
                                                       operable pumps was 
                                                       met. 

     The inspector considers the mechanical failures associated with this 
     event to be corrected. 

     Licensee investigation into this event concentrated on reviewing the 
     procedure (PT 10 a and b) as well as expected operator actions. 
     Although two additional licensed operators familiar with PT 10 a and b 
     were brought in specifically to perform the test, it was determined 
     that the degree of communication between the two individuals by sound 
     powered telephone could have been improved. (One individual was in the 
     control room and one individual was in the auxiliary electrical area). 
     Furthermore, it was concluded that human engineering deficiencies in 
     the auxiliary electrical area which require simultaneous depression of 
     three separate pushbuttons to develop the safeguards signals 
     contributed to the error. 
     
     During the management exit held on June 1, 1979, periodic test 
     procedure PT 10a and b was discussed as well as possible changes that 
     were going to be made. These changes dealt with modifications to the RP 
     pushbutton as well as some procedural modification. At the time of the 
     management exit, these changes were not finalized. Consequently, this 
     item will be carried as unresolved pending further resolution by the 
     licensee and will be followed in subsequent inspections. (295/79-13-01; 
     304/79-12-01) 
          

     No items of noncompliance were identified. 

3.   QA Audit Performed by Commonwealth Edison 

     The inspector was made aware of the results of an inhouse quality 
     assurance audit performed by the corporate off-site audit group. One 
     significant finding was made regarding implementation of Zion 
     Administrative Procedure 13-52-8. According to the audit finding all of
     the requirements of ZAP13-52-8, which controls the shipment of dry 
     active wastes, were not being implemented. 

                                   - 4 -
.

    The inspector discussed this item with the plant's Quality Assurance 
     Department as well as at the monthly exit. The ZAP in question will be 
     controlling the anticipated future shipment of old spent fuel racks. 
     The licensee stated that these problems were being resolved and a 
     formal response to the in-house audit would be available shortly. At 
     the time of the management exit, these changes had not been finalized. 
     Consequently, this item will be considered unresolved pending 
     resolution by the licensee. (295/79-13-02; 304/79-12-02) 
     
     No items of noncompliance were identified. 

4.   Unit 2 Reduction in Plant Load May 11, 1979 

     Unit 2 Reduction in Plant Load 79 Unit 2 entered a limiting condition 
     for operation regarding Technical Specification 4.8.3.c at about 9:00 
     a.m. on May 11, 1979, when it was found that the 0 diesel generator 
     would not except load during the time the 2A residual heat removal 
     (RHR) pump was out of service for maintenance. A 2.5% per minute load 
     reduction was begun with the anticipated off line time at 1:00 P.M. The
     load reduction was cancelled at approximately 12:30 p.m. when the 2A 
     RHR pump maintenance was completed and the pump was tested and declared 
     operable. The inspector has no further questions regarding this item. 
     
     No items of noncompliance were identified. 

5.   Special Engineered Safeguards Inspection 

     As a result of the Three Mile Island incident, the inspector conducted 
     a special inspection of all engineered safety feature systems at the 
     Zion Generating Station. The results of this inspection are contained 
     in a special inspection report which was forwarded to the licensee in 
     June of 1979. The inspector has no further questions regarding this 
     item. 

6.   Plant Cleanliness 

     The inspector commented during the management exit on 6/1/79 that the 
     auxiliary building looked clean and that licensee personnel should 
     continue housekeeping efforts, particularly in any areas where boric 
     acid might deposit and crystallize. 

     No items of noncompliance were identified. 

7.   Technical Specification Comments 

     During the month, an item pertaining to the Zion Technical 
     Specifications was discussed with operating personnel. This item and 
     the inspector's comment are as follows: 

                                   - 5 -
.

     Operability of a diesel generator: Is a diesel generator which is 
     running, loaded, and parallelled to its safety bus considered operable 
     at the Zion Generating Station while maintenance is being performed on 
     its air starting system? 

     Answer: Regarding the Zion diesel generators, the diesels are 
     considered operable as long as all safety functions can be performed 
     while running during the maintenance on the air starting system. If the 
     diesel generator trips during maintenance, a limiting condition for 
     operation would exist and the diesel generator would not be declared 
     operable until all maintenance items were completed and a successful 
     periodic test performed. 
     
8.   Testimony Preparation for Spent Fuel Pool Expansion 

     During the month, written testimony was prepared by the inspector for 
     the public bearing regarding plans to increase the storage capacity of 
     the spent fuel pool. In preparation for this hearing the Quality 
     Assurance, Quality Control and Fuel Handling Departments were 
     contacted. In addition, a noncompliance history regarding Quality 
     Assurance at the Zion Generating Station was reviewed and discussed 
     with other members of Region III office. 
     
     No items of noncompliance were identified. 

9.   Review of Plant Operations 

     During the month, the inspector made tours of the turbine building, 
     auxiliary building, control room and the perimeter and security areas. 
     With regard to the plant, the tours involved valve lineup audits, 
     review of LCO conditions, discussions with plant operating personnel, 
     review of station logs, and review of overall plant cleanliness. The 
     security tours involved witnessing badging vehicle searching, package 
     surveillance and compliance with station visitor policy. 
     
     No items of noncompliance were identified. 

10.  Plant Maintenance 

     The inspector either witnessed or reviewed the results of the following
     maintenance activities during the month to determine if work control 
     procedures and required supervision were in effect. The following is a 
     list of the maintenance activities involved in the review: 

     a.   IM maintenance on MA station 2C FW pump to repair the speed 
          controller. 

                                   - 6 -
.

     b.   2A RHR pump seal replacement. 

     c.   Starting air leaks in "0" D/G. 

     d.   B MSIV failure in close from Train A. 

     e.   FW Reg Valve failure to close from Train A. 

11.  Unresolved Items 

     Unresolved items are matters about which more information is required 
     in order to ascertain whether they are acceptable items, items of the 
     noncompliance, or deviations. Unresolved items disclosed during 
     inspection are discussed in Paragraphs 2 and 3. 

12.  Management Interview 

     A management meeting was held on June 1, 1979, by the resident 
     inspector with Mr. Wandke and others of his staff in which the results 
     of the inspection were summarized. 

                                   - 7 -
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