ML18066A921

Responds to NRC Re Violations Noted in Insp Rept 50-255/96-17.Corrective Actions:Feedwater Controls Turned to Minimize Feedwater Flow Oscillations

ML18066A921
Person / Time
Site:	Palisades
Issue date:	03/19/1997
From:	Thomas J. Palmisano CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9703270178
Download: ML18066A921 (5)

Text

consumers Power POW ERi Nii

/llllCHlliAN"S PROGRESS Palisades N_uclear Plant: 27780 Blue Star Memorial Highway, Covert, Ml 49043 March 19, 1997 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR-20 ~ PALISADES PLANT REPLY TO NOTICE OF VIOLATION 96017-FAILURE TO MAINTAIN PRIMARY-COOLANT TEMPERATURE ABOVE S25°F WHILE REACTOR CRITICAL NRC Inspection Report No. 50-255/96017 contains a Notice of Violation which concerns a failure to comply with Technical Specifications 3.1.3.a which states, "Except during low-power physics test, the reactor shall not be made critical if th~ primary ;,_

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. coolant temperature is below 525°F." *The inspection report states that, ~Contrary t,o t_he -

.-,:a_bov~:- on,,January 6;.1997, at 2:11 pm:. the primary coolantsystem.t~rnp_er~tu~:* ;.. :>.:;._*.,_,_:... <** :

. decreased below 525°F for approximately one minute with the reactor critical."

Consumers Power Company agrees with this violation. The attachment to this letter provides the reply to this violation. This event was previously reported on Liqen_see. '.*-:

Event Report 97-001 dated February 5, 1997.

SUMMARY

OF COMMITMENTS This letter contains no new commitments.and-no revisions-to-existing cornmifrrients: -----*-

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• • Thomas J.*Palmisano Site Vice President CC Administrator, Region Ill-, USNRC Project Manager, NRR, USNRC NRC Resident Inspector - Palisades

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.. Attachment

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9703270178 970319 PDR ADOCK 05000255 G

PDR A CMS'~COMPANY

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ATTACHMENT CONSUMERS POWER COMPANY PALISADES PLANT.

DOCKET 50-255

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REPLY TO NOTICE OF VIOLATION 96017.

• FAILURE TO MAINTAIN PRl~ARY COOLANT TEMPERATURE., :

ABOVE 525°F:WHILE REACTOR CRITICAL **

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3 Pages

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REPLY TO NOTICE OF VIOLATION 96017 Y. * :' ~

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FAILURE TO MAINTAIN PRIMARY COOLANT TEMPERATURE

• ABOVE 525°F WHILE REACTOR CRITICAL NRC VIOLATION During an NRC inspection conducted on November 24, 1996 through January 10, 1997, a violation of NRC requirements was identified. In accordance with the "General Statement of Policy and Procedure for NRC Enforcement Actions," NUREG-1600, the violation is listed below:

Technic~I Specification 3.1.3 a) states: "Except during low-power physics test, the reactor shall not be made criticai if the primary coolant temperature i$ below 525°F."

Contrary.to the above, on January 6, 1997, at 2:11 pm, the primary coolant system temperature decreased below 525° F for approximately one minute with the reactor critical.

. CONSUMERS POWER COMPANY RESPONSE

• <*eac~groi.md. _*.

• r t On January 6, 1997, operators practiced synchronizing the Main Generator to the grid using the simulator.. A reactor power increase of 2-3% was assumed to account for the additional steam flow with the turbine on line and the Turbine Bypass Valve NllY closed.

A reactivity change using control rods was estimate~ using the Technieal*Data book. it was determined that rod withdrawal of 3-4 inches should balance the increased steam *

. flow. This assumption was validated when the task was successfully performed on the simulator.

• The same operators proceeded with the Main Generator synchronization. They.

• expected to only have to withdraw rods -4 inches or at most 8 inches to stabilize TAVE*

When TAVE did not stabilize above 525°F, significant additional control rodwithdrawal (a

• . tot~I of 18 lnc~es) was requ.ired that had not been anticipated by. the.operators:_\\.. '

• Therefore, the* careful and deliberate manner that the operators took *in withdrawing the

• control rods on this occasion failed to increase reactor power sufficiently to prevent TAVE decreasing below 525°F. The 18 inches of withdrawal is consistent with what was seen during the startups on December 27, 1996, and on January 14, 1997. *

• Differences between the expected plant response and the actual plant response contributed to this event. The Turbine Bypass Valve was discovered to have an

unattached packing follower on the valve actuator. Therefore, the actual operatin*g

• characteristics of the Turbine Bypass Valve during this evolution are unknown.

Additionally, feedwater oscillations occurring at the time may have aggravated the plant cooldown. Both conditions, therefore, probably caused an actual plant response of greater magnitude th~n the operators were* led to anticipate.

Based on interviews and discussions with the operators involved, there were no knowledge deficiencies or inadequate skills that contributed ~o this event.. In addition,*

there is no safety significance to a TAVE of 524°F for less than one minute with the reactor critical. The current Technical Specifications (TS).allow one hour to rectify the.

,situation prior to initiating a plant shutdown per TS 3:0.3.

Reason for Violation Task planning was not comprehensive enough to prepare the operators to recognize and implement the necessary contingency and compensatory actions required for the plant an.d equipment responses that were actually experience~:

Additionally, Turbine Byp~ss Valve CV-0511 may have contributed to the severity ofthe

. primary.system cooldown. An unattacned packing follower on the valve ~ctuatormay_.

have *resulted in erratic valve movement during its operation that would not have be~n *

read~*ly noticed by the 'op'erators.

• The lessons learned from this ev~nt included:

The over-reliance placed on the simulator. and *the Technical Data book to

. exactly model actual plant response led to a task plan that was not *s.ufficiently.

comprehen~ive to prevent the event. Operators did not fully anticipate.the differences between the expected plant response and actual plan.t responses to

• develop th.e necessary contingencies and compensatory actions that would have *

.. prepared the op.erat~rs to handle any departure from what was practiced.*

Equipment and system conditions and performance should be investigated and factored into task plans. In this event, a feedwater regulation sy~tem oscillati9n should have been evaluated for its effect on temperature control.'. The feedwater

.. regulation system' oscillation had a* larger effect on primary coolant system-...

temperature due to beginning of core life conditions.* The beginning of ci:>re life:

conditions inclu.ded a low amount of reactor decay_ heat and a slightly negative Moderator Temperature Coefficient.

Task preparation and planning should consider previous operating experience.

Placing the g_e.nerator on line on December 27, 1996, required a control rod

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withdrawal of similar magnitude as that which was ultimately needed on January 6, 1997.

Corrective Action Taken and Results Achieved The following corrective actions were taken:

1.

Senior Operations Management has reviewed these events with all crews to emphasize and discuss the lessons learned stated above. These discussions took place with all crews prior to plant startup.

2.

The.Turbine Bypass Valve Actuator was repaired.

3.

Feedwater con~rols were tuned to minimize the feedwater flow oscillations.

Corrective Actions Remaining to Avoid Future Violations Noadditional corrective actions are planned.

Pate Eull Compliance Will Be Achieved Consumers Power Company is now in full compli~nee.

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