ML20236K557

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Forwards Writeup for AO Rept to Congress for Second Quarter CY86 in Response to 860701 Memo.Premature Criticality During Facility Startup Addressed
ML20236K557
Person / Time
Site: San Onofre, 05000000
Issue date: 07/17/1986
From: Martin J
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To: Heltemes C
NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
Shared Package
ML20236K265 List:
References
FOIA-87-377 NUDOCS 8708070161
Download: ML20236K557 (7)
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Text

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! :rci 'o UNITED STATES M. '

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NUCLEAR REGULATORY COMMISSION Sc O ml REGION V gg s-

  • y, 1450 MARIA LANE, SUITE 210

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          • JUL 171986 MEMORANDUM FOR: C. J. Heltemes, Jr., Director Office for Analysir and i Evaluation of Operational Data FROM: J. B. Martin, Regional Administrator

SUBJECT:

ABNORMAL OCCURRENCE REPORT TO CONGRESS FOR SECOND QUARTER CY 1986 Attached are proposed writeups for the subject report in response to your memorandum of July 1, 1986. .

By memorandum, J. L. Montgomery to C. J. Heltemes, dated July 9, 1986, we forwarded a proposed A0 regarding a diagnostic misadministration at Tripler Army Medical Center.

A proposed Enclosure 3 item was forwarded to your office by memorandum D. F.

Kirsch to F. Hebdon, dated April 30, 1986. We will review the writeup your office proposed to prepare covering a series of such events and provide appropriate comments at that time.

l Should you have questions regarding the ite.is proposed for the subject report,  !

please contact Jess Crews or Bobby Faulkenberry of my staff.  !

/4 (2 . .

p'w . B. Martin Regicnal Admini ator

Enclosures:

1. Appendix B Items - A0 85-1 (update) and A0 86-1 (update)
2. Appendix C Item - Suspected Sabotage (Palo Verde Nuclear Generating Station) cc w/ enclosures:

J. Crews A. Chaffee P. Johnson P. Narbut R. Huey N

'N x 8708070161 870'804 PDR FOIA PDR E GORDON87-377 3

'. . l I

Enclosure 1 APPENDIX B UPDATE OF PREVIOUSLY REPORTED ABNORMAL OCCURRENCES 85-1 Premature Criticality During Startup 1

{ This abnormal occurrence was originally reported in NUREG 0090, Volume 8, No. 1. The item involved Summer Unit 1. It is updated to describe a somewhat similar event which occurred at San Onofre Unit 3 on April 13, 1986.

San Onofre Premature Criticality l

At 11:16 a.m. on April 13, 1986, while the licensee was performing a recovery from a spurious reactor trip which had occurred 'the previous day, the reactor tripped after achieving criticality at a withdrawal l position lower than predicted by the Estimated Critical Position (ECP). '

The licensee made a 4-hour report of the reactor tip to the NRC Duty Officer at 3:00 p.m. PST. This ENS report indicated that the reactor had tripped on departure from nucleated boiling ratio (DNBR) and local power .

density (LPD) trip signals generated by the core protection calculator I (CPC), because of penalty factors resulting from minor control rod misalignments. The following sequence of events occurred:

i Operations personnel calculated an ECP of 60 inches on group 6, l

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l based on an estimated criticality at 11:00 a.m. Although two s l

previous startups had been conducted since the first refueling i outage which ended in early 1986, this was the first startup with j significant xenon present. '

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  • Regulating groups 1, 2, and 3 were withdrawn to their upper group limits. However, they were not individually aligned to uniform height at the fully withdrawn position, as specified in the j procedure, because of preoccupation with achieving criticality near the 11:00 a.m. time on which the ECP was based. As a result, some group 1 rods were inserted approximately one inch more than group 2 rods, which generated an out-of-sequence penalty factor signal to the CPC. The operators' intent was to dress the rods after criticality was achieved before the penalty factors became effective (at 10E-4% power).

When group 4 rods reached approximately 80 inches withdrawn, the reactor achieved criticality (at approximately 10E-5% power). This was not immediately recognized by the operator and rod withdrawal continued to approximately 114 inches before the critical condition was recognized. The reactor controls were being manipulated by a reactor operator trainee under the direct supervision of a licensed reactor operator. Other licensed personnel were present in the control room.

When criticality was recognized, the operator began inserting control rods. However, power had by this time reached 10E-4% power,

l at whf-h point the CPC reactor trips were enabled. Increasing penalty factors as the rods were inserted initiated DNBR and LPD reactor trips at a rod position of 98 inches on' group 4. Actual unsafe DNBR or LPD conditions did not exist. Peak reactor power i during the transient was approximately 10E-2%, with startup rates in  !

the range of 1.5 to 1.7. decades per minute. )

The licensee determined on April,13, following the trip, that the  !

incorrect ECP was caused by incorrect xenon tables (used to predict the I reactivity worth of xenon) in the. Operations Physics Data Summary' Book.

Due to. improper administrative control of the ECP data, the xenon tables for cycle 1 operation were being usca instead of the tables required for cycle 2. Indications are that the licensed operator who was performing the t,tartup (i.e., supervising the trainee) also did not devote appropriate attention to availabie indications of approaching criticality and was not anticipating criticality "at any time" as directed by the approved procedure.

Following a post-trip review by the licensee and an appropriate addition of boron, Unit 3 started up later on April 13 and was operating at full power on April 14.

l On June 20, 1986, a Nati.:e of Violation was transmitted to the licensee '

for failure to closely monitor nuclear instrumentation and for failure to recognize the premature criticality.

86-1 Loss of Power and Water Hammer Event This abnornal occurrence involving San Onofre Unit I was originally reported ,

in NUREG 0090, Volume 9, No. 1. It is updated to provide significant updating l l eaterial.

San Onofre Unit 1 Yhe licensee and principal NRC staff members met with the Commissioners on June 12, 1986. The Commissioners reviewed the licensee's and staff's actions taken to analyze and correct the deficiencies that led to the i event. Principal ancng these actions was the development and i implementation of a Material Condition Review Program. The program was designed to define a suitable material standard for-systems and components in an older plant and to ensure that the material condition of those items was maintained.

, The NRC Office of Inspection and Enforcement issued an Information l

Notice to all nuclear power facilities on June 16, 1986. describing environmentally induced aging of an electrical power cable, the degradation of which contributed to the initiation of this event.

On June 25, 1986, the Region V Administrator visited the site to assess the material condition of Unit 1. Although minor deficiencies were identified, the Unit Condition was found to be greatly improved from what it had b$en prior to the November 21, 1985 event.

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l _ _ _ . _ _ _ _ _ ______________a

On July 13, 1986, the Regional Administrator concurred with the restart of Unit 1. The unit achieved criticality on July 15, 1986 in prepnation-for return to service. .

l This item is considered closed for purposes of reporting in this NRC document.

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Enclosure 2 l

Appendix C OTHER EVEWTS OF INTEREST l

1. Suspected Sabotage (Palo Verde Nuclear Generating Station).

On hay 14, 1986, beginning at approximately .B:59 pm, PDT, offsite power on 3 of 4 transmission lines was lost due to phase-to ground faults on each line. The power remained faulted through the evening until the afternoon of May 15, 1986. During the morning hours of May 15, the l licensee found that a rope or strap had been slung over the transmission I lines causing a phase to ground fault. The fault locations on each line 1 l was about 35 miles from the plant. l l

The transmission lines converge on the site frem 4 different directions. l l

The ground straps were far enough apart to require a coordinated effort l by several individuals to accomplish the power loss within a few minutes.

Unit I was in Mode 5 for a maintenance outage. Unit 2 remained in Mode 3 pending completion of the investigation of the event. Unit 3 was in the  !

preoperational test phase, with no fuel in the reactor.

1 The licensee notified local law enforcement agencies and the TPI.

1 In accordance with Title 18, Section 1365 3US Code, the FBI (Phoenix l Office) assumed principal jurisdiction of this incident. They l coordinated their investigative efforts with the Maricopa County Sheriff's Office, the Arizona Department of Public Safety and NRC OI (Region V). The FBI continues to analvze physical evidence obtained at j each of the three areas. l The licensee has offered a $25,000 recard for " information leading to the arrest acd conviction of the person or persons responsible for the May 14 sabotage of three major high-voltage lines tied to the Palo Verde Nuclear Generating Station."

The event is of considerable concern because it was deliberate, coordinated sabotage by a group of people. In this event, there was no challenge to plant safety system because cffsite power remained available through the non-faulted transmission line. The plants were all designed to safely shutdown without any offsite power. However, until the saboteurs are apprehended, the potential for futurc challenges to the plant safety systems remains.

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