ML18067A646

Forwards 120-day Response to GL 97-01, Degradation of Control Rod Drive Mechanism Nozzle & Other Vessel Closure Head Penetrations.

ML18067A646
Person / Time
Site:	Palisades
Issue date:	07/29/1997
From:	Thomas J. Palmisano CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-97-01, GL-97-1, NUDOCS 9708050124
Download: ML18067A646 (11)

Text

A CMS Energy Company Palisades Nuclear Plant Tel: 616 764 2296 27780 Blue Star Memorial Highway Fax: 616 764 2425 Covert, Ml 49043 11Jama* J. Palmluao Site Vice President July 29, 1997 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 DOCKET 50-255 - LICENSE DPR PALISADES PLANT 120-DAY RESPONSE TO GENERIC LETTER 97-01, "DEGRADATION OF CONTROL ROD DRIVE MECHANISM NOZZLE AND OTHER VESSEL CLOSURE HEAD PENETRATIONS" On April 1, 1997, the NRC issued Generic Letter (GL) 97-01, "Degradation of Control Rod Drive Mechanism Nozzle and Other Vessel Closure Head Penetrations". On April 28, 1997, Consumers Energy Company submitted their 30-day response which included the following commitment:

"The information requested by GL 97-01 will be submitted within 120 days from April 1, 1997. If the schedule for submittal or the content of the report needs to be revised from that requested in GL 97-01, Consumers Energy will provide appropriate notification to the NRC."

This letter submits the 120-day response to GL 97-01 and fulfills the above commitment. This response is contained in the Attachment to this letter.

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SUMMARY

OF COMMITMENTS This letter contains no new commitments and no revisions to existing commitments.

Thomas J. Palmisano Site Vice President, Palisades CC Administrator, Region Ill, USNRC

.Project Manager, NRR, USN RC NRG Resident Inspector - Palisades Attachment

CONSUMERS ENERGY COMPANY To the best of my knowledge, the contents of this 120-day response to Generic Letter 97-01, are truthful and complete.

By ~)'7.L_ *:--

Tho~ Palmisano Site Vice President, Palisades Sworn and subscribed to before me this c:;i_qth day of ~ 1997.

~~4V Mary Ann Engle, Notary Public Berrien County, Michigan (Acting in Van Buren County, Michigan)

My commission expires February 16, 2000

[SEAL]

ATTACHMENT CONSUMERS ENERGY COMPANY PALISADES PLANT DOCKET 50-255 120-DAY RESPONSE TO GENERIC LETTER 97-01, "DEGRADATION OF CONTROL ROD DRIVE MECHANISM NOZZLE AND OTHER VESSEL CLOSURE HEAD PENETRATIONS" 7 Pages

• ATTACHMENT 120-DAY RESPONSE TO GENERIC LETTER 97-01, "DEGRADATION OF CONTROL ROD DRIVE MECHANISM NOZZLE AND OTHER VESSEL CLOSURE HEAD PENETRATIONS" INTRODUCTION Generic Letter (GL) 97-01, "Degradation of Control Rod Drive Mechanism Nozzle and Other Vessel Closure Head Penetrations," was issued to request licensees to describe their program for ensuring the timely inspection of PWR control rod drive mechanism (CROM) and other closure head penetrations. This response provides the information as requested by the GL for the Palisades Plant.

Prior to issuance of the GL, Palisades has worked with the Combustion Engineering Owners Group (CEOG) since 1989, the Electric Power Research Institute (EPRI), and the Nuclear Energy Institute (NEI). This assisted Palisades in our effort to understand the operational experience of reactor nozzles and other head penetrations, and to identify related technical issues, causal factors, relative importance, and solutions. One of the tasks identified was the development of safety evaluations that characterize damage initiation, propagation and consequences. These safety evaluations and the subsequent safety evaluation report (SER) from the NRC are'summarized in CE NPSD-1085, Revision 0, "CEOG Response to NRC Generic Letter 97-01, Degradation of CEDM Nozzle and Other Vessel Closure Head Penetrations," which was submitted on July 25, 1997, under separate cover by ABB for the CEOG.

Following is the information requested for the 120-day response to GL 97-01:

NRC REQUESTED. INFORMATION. ITEM 1.1

1. 1 A description of all inspections of CROM nozzle and other VHPs pefformed to the date of this generic letter, including the results of these inspections 1.

1 Those licensees that have previously submitted the requested information need not resubmit it, but may instead reference the appropriate correspondence in their response to this Generic Letter.

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• ATTACHMENT 120-DAY RESPONSE TO GENERIC LETTER 97-01, "DEGRADATION OF CONTROL ROD DRIVE MECHANISM NOZZLE AND OTHER VESSEL CLOSURE HEAD PENETRATIONS" CONSUMERS ENERGY COMPANY RESPONSE. ITEM 1. 1 Palisades vessel head penetration (VHP) inspections are identifieo and discussed in CE NPSD-1085, Revision 0, "CEOG Response to NRC Generic Letter 97-01, Degradation of CEDM Nozzle and Other Vessel Closure Head Penetrations".

As described in CE NPSD-1085, Revision 0, Palisades inspected eight in-core instrumentation nozzles by eddy current testing in the 1995 refueling outage, as part of the Palisades Alloy 600 Inspection Program. No crack indications were detected.

Palisades also conducted bare metal external visual inspection of all 54 VHPs during the 1995 refueling outage. No evidence of nozzle leakage was found.

The Palisades Nuclear Plant Alloy 600 Project Plan was furnished to the Nuclear Regulatory Commission prior to the 1995 inspection in submittals dated February 27, 1995, and June 15, 1995. NRC Palisades site resident inspectors, Region Ill personnel, and NRR were kept informed of the inspection program during its development and execution. We will continue to work with the CEOG to maintain an

• information flow to the NRC.

NRC REQUESTED INFORMATION. ITEMS 1.2 THROUGH 1.4

1. 2 If a plan has been developed to periodically inspeet the CROM nozzle and other VHPs:

a. Provide the schedule for first, and subsequent, inspections of the CROM nozzle and other VHPs, including the technical basis for this schedule.

b. Provide the scope for the CROM nozzle and other VHP inspections, including the total number of penetrations (and how many will be inspected), which penetrations have thermal sleeves, whic,h are spares, and which are instrument or other penetrations.

1. 3 If a plan has not been developed to periodically inspect the CROM nozzle and

• other VHPs, provide the analysis that supports why no augmented inspection is necessary.

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• ATTACHMENT 120-DAY RESPONSE TO GENERIC LETTER 97-01, "DEGRADATION OF CONTROL ROD DRIVE MECHANISM NOZZLE AND OTHER VESSEL CLOSURE HEAD PENETRATIONS" 1.4 In light of the degradation of CROM nozzle and other VHPs described above, provide the analysis that supports the selected course of act!on as listed in either

1. 2 or 1. 3, above. In particular, provide a description of all relevant data and/or tests used to develop crack initiation and crack growth models, the methods and data used to validate these models, the plant-specific inputs to these models, and how these models substantiate the susceptibility evaluation. Also, if an integrated industry inspection program is being relied on, provide a detailed description of this program.

CONSUMERS ENERGY COMPANY RESPONSE. ITEMS 1.2 THROUGH 1.4 Palfsades completed planned VHP inspections during the 1995 refueling outage as part

. of the Palisades Alloy 600 Inspection Program. Based on acceptable results, and ongoing work with the CEOG, Palisades has not scheduled further inspections.

Palisades intends to work with the CEOG to evaluate inspection results from other CEOG plants, and to determine if additional inspections should be performed.

Request Item 1.2 Palisades inspected eight in-core instrumentation nozzles by eddy current testing in the 1995 refueling outage, as part of the Palisades Alloy 600 Inspection Program. No indications of corrosion were found. The Palisades Nuclear Plant Alloy 600 Project Plan, provided to the Nuclear Regulatory Commission before the 1995 inspection, includes penetration details and considerations used in

• inspection prioritization and methods. In addition, as discussed above, Palisades conducted bare metal external visual inspection of all 54 VHPs during the 1995 refueling outage with no evidence of leakage found.

Palisades VHP characteristics, including the total number of penetrations, which

• penetrations have thermal sleeves, which are spares, which are instrument or other penetrations, and plant-specific cracking model inputs, are also summarized in Tables 1 and 2 of CE NPSD-1085, Revision 0, "CEOG Response to NRC Generic Letter 97-01, Degradation of CEDM Nozzle and Other Vessel Closure Head Penetrations". Details of the CEOG integrated industry inspection program are described in Section 2.4 of CE NPSD-1085, Revision 0.

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• ATTACHMENT 120-DAY RESPONSE TO GENERIC LETTER 97-01, "DEGRADATION OF CONTROL ROD DRIVE MECHANISM NOZZLE AND OTHER VESSEL CLOSURE HEAD PENETRATIONS" Reguest Item 1.3 Palisades is a participant in the CEOG VHP integrated inspection program. The program is described in CE NPSD-1085, Revision 0, "CEOG Response to NRC Generic Letter 97-01, Degradation of CEDM Nozzle and Other Vessel Closure Head Penetrations". Based on 1995 Palisades inspection results and on expectation that relevant data from CEOG inspection activities will be forthcoming, Palisades has not currently scheduled any further inspections.

Reguest Item 1.4 The CEOG, using a probabilistic inspection timing model, has identified certain CEOG plants to have higher probability for stress corrosion cracking. This timing model is described in Section 2.4 of CE NPSD-1085, Revision 0, "CEOG Response to NRC Generic Letter 97-01, Degradation of CEDM Nozzle and Other Vessel Closure Head Penetrations". The two.pl~mts with the highest identified susceptibility are currently planning future inspections. Palisades, working with the CEOG, will use these inspection results to assist in determining what additional inspection may be needed at Palisades.

In addition to the CEOG integrated inspection plan, all three PWR owners groups, EPRI, and the NEI are cooperatively working through the NEI to compile information on the estimated remaining operating time from January 1, 1997, needed to initiate and propagate a crack 75% through-wall in a vessel penetration. This information will be evaluated to determine if an adequate number of plants have inspected or are planning to inspect their penetrations.

Results of the joint task are expected in late 1997 or early 1998 and will be provided to the NRC in accordance with the CEOG plan.

NRC REQUESTED INFORMATION. ITEM 2

2.

• Provide a description of any resin bead intrusions, as described in IN 96-11, *that have exceyded the current EPRI PWR Primary Water Chemistry Guidelines recommendations for primary water sulfate levels, including the following information:

2. 1 Were the intrusions cation, anion, or mixed bed?

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• ATTACHMENT 120-DAY RESPONSE TO GENERIC LETTER 97-01, "DEGRADATION OF CONTROL ROD DRIVE MECHANISM NOZZLE AND OTHER VESSEL CLOSURE HEAD PENETRATIONS" 2.2 What were the durations of these intrusions?

• 2.3 Do the plant's RCS water chemistry Technical Specifications follow the EPRI guid~lines?

2. 4 Identify any RCS chemistry excursions that exceed the plant administrative limits for the following species: sulfates, chlorides or fluorides, oxygen, boron, and lithium.

2. 5 Identify any conductivity excursions which may be indicative of resin intrusions. Provide a technical assessment of each excursion and any follow-up actions.

2. 6 Provide an assessment of the potential for any of these intrusions to result in a signifi.cant increase in the probability for /GA of VHPs and any associated plan for inspections.

CONSUMERS ENERGY COMPANY RESPONSE. ITEM 2 CE NPSD-1085, Revision 0, "GEOG Response to NRC Generic Letter 97-01, Degradation of CEDM Nozzle and Other Vessel Closure Head Penetrations", Section3, includes the GEOG integrated response to these questions. The following paragraphs summarize the GEOG report as it relates to Palisades:

Reguest Items 2.1 and 2.2 Palisades experienced a large release of predominantly anion resin during plant preoperational testing in 1970. The release was terminated and the primary coolant system was disassembled,.flushed, and cleaned prior to resumption of testing. Palisades has not had any known resin intrusions since the 1970 event.

This event and corrective actions are also described in Section 3.1 of CE NPSD-1085, Revision 0, "GEOG Response to NRC Generic Letter 97-01, Degradation of CEDM Nozzle and Other Vessel Closure Head Penetrations".

Eddy current testing and dye penetrant examinations of in-core instrumentation nozzles during 1995 found no corrosion, demonstrating the 1970 resin intrusion had no effect (ibid, Section 3.6).

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ATTACHMENT 120-DAY RESPONSE TO GENERIC LETTER 97-01, "DEGRADATION OF CONTROL ROD DRIVE MECHANISM NOZZLE AND OTHER VESSEL CLOSURE HEAD PENETRATIONS" Consumers Energy has reviewed the plant historical records to determine if any incident of resin ingress similar to those of 1980 and 1981 at the Jose Cabrera (Zorita) plant has occurred at Palisades. The data search employed the screening criteria in Section 3.1 of CE NPSD-1085, Revision 0, "CEOG Response to NRC Generic Letter 97-01, Degradation of CEDM Nozzle and Other Vessel Closure Head Penetrations," to define and identify significant events of resin intrusion into the primary coolant system. Results of the data search are documented in Sections 3.1 through 3.6 of the same document.

The data search consisted of reviewing primary coolant system conductance and sulfate measurements which have been made and stored in the Palisades Chemistry Data Management System since December 1987 and March 1989, respectively. Known plant history and results of 1995 VHP inspections were used to identify and evaluate resin ingresses occurring before December 1987.

No corrosion was found in any of the eight incore instrumentation nozzles internally examined in 1995.

Reguest Item 2.3 EPRI PWR Primary Water Chemistry Guidelines are not specifically included in the Palisades Technical Specifications. Current EPRI PWR Primary Water Chemistry Guidelines are considered in the development of Palisades plant administrative procedures for establishment of plant chemistry limits. In accordance with administrative procedures, Palisades takes corrective action if chemistry limits are exceeded.

Sulfates are identified as a screening criteria in the CEOG report. Palisades does hot have an upper limit for sulfates but takes corrective action when the normal value exceeds 20 ppb. The EPRI guidelines establish an upper limit for sulfates of 50 ppb. This item is discussed further in Section 3.3 of CE NPSD-1085, Revision 0, "CEOG Response to NRC Generic Letter 97-01, Degradation of CEDM Nozzle and Other Vessel Closure Head Penetrations."

Reguest Items 2.4. 2.5. and 2.6 Sections 3.1 and 3.4 of CE NPSD-1085, Revision 0, "CEOG Response to NRC Generic Letter 97-01, Degradation of CEDM Nozzle and Other Vessel Closure Head Penetrations," discuss chemistry parameters as indicators of Zorita-type resin 6

• ATTACHMENT 120-DAY RESPONSE TO GENERIC LETTER 97-01, "DEGRADATION OF CONTROL ROD DRIVE MECHANISM NOZZLE AND OTHER VESSEL CLOSURE HEAD PENETRATIONS" intrusion events leading to sulfate induced IGA. The PWR Owners Groups and NEI Alloy 600 RPV Head Penetration Task Force, determined that primary coolant system conductance and sulfate measurements are suitable screening criteria for evaluating chemistry data that would be most indicative of resin intrusion. If either specific conductance or sulfate increases should indicate resin ingress at or exceeding the screening values, additional reviews of other chemistry parameters would be conducted. Corroborating indicators of large resin ingress were considered to be, for example, pH depression, elevated lithium and elevated suspended solids. Other chemistry parameters were not considered to be dependable primary indicators of resin intrusion.

Review of primary coolant system conductance and sulfate measurements stored in the Palisades Chemistry Data Management System since December 1987 and March 1989, respectively, did not reveal any conductivity or sulfate excursions that exceeded the screening criteria in Section 3.1 of CE NPSD-1085, Revision 0, "CEOG Response to NRC Generic Letter 97-01, Degradation of CEDM Nozzle and Other Vessel Closure Head Penetrations." Because the screening criteria did not indicate resin intrusion into the primary coolant system, additional reviews of other chemistry parameters (boron, chlorides, fluorides, lithium, and oxygen) were not considered to be necessary.

Eddy current testing and dye penetrant examinations of in-core instrumentation nozzles during 1995 found no *corrosion, demonstrating that if any earlier resin intrusions had occurred, they had no effect (ibid, Section 3.6).

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