IR 05000321/1993010

Insp Repts 50-321/93-10 & 50-366/93-10 on 930608-11.No Violations Noted.Major Areas Inspected:Potential Effects of Licensee Leaking Fuel Issue Upon Radwaste Sys & Impact Upon Public Health & Safety During Power Ascension to 100%

ML20046C235
Person / Time
Site:	Hatch
Issue date:	07/09/1993
From:	Robert Carrion, Decker T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:
Shared Package
ML20046C232	List: IR 05000321/1993010 ML20046C231
References
50-321-93-10, 50-366-93-10, NUDOCS 9308100022
Download: ML20046C235 (7)

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UNITED STATES NUCLEAR REGULATORY COMMisslON

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E 101 MARIETTA STREET, N.W.

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JUL 9 1993

Report Nos.: 50-321/93-10 and 50-366/93-10 Licensee: Georgia P'wer Company P. O. Box 1295 Birmingham, AL 35201 l'

Docket Nos.: 50-321 and 50-366 License Nos.: DPR-57 and NPF-5 Facility Name: Hatch I and 2 Inspection Condu ted: June 8-11, 1992

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7 J"' r I 3 Inspector: /

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p. P. Carrion, Radiation Specialist Date Signed

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i 2-7/ /k7 Approved by:

b OIo T. R. Decker, Chief Date Signed Radiological Effluents and Chemistry Section Radiological Protection and Emergency Preparedness Branch Division of Radiation Safety and Safeguards SUMMARY Scope:

This special, announced inspection was conducted to determine potential effects of the licensee's leaking fuel issue upon its radwaste systems and its impact upon public health and safety during power ascension-to 100 percent.

Results:

-The licensee's program was adequate to support power ascension to full capacity. The Off Gas System was well-maintained and its monitors were calibrated and could isolate the system under non-routine conditions. The Holdup System was capable of meeting its minimum thirty minute holdup requirement. Gaseous releases and their associated estimated doses were well within TS limits; the maximum estimated dose over the previous ~ three calendar j

quarters was slightly under four percent of the limit. The licensee had written new work procedures to prevent any foreign debris from entering the Primary Loop with the potential of causing fretting fuel failures.

9308100022 930709 PDR ADDCK 05000321 O

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REPORT DETAILS 1.

Persons Contacted Licensee Employees

• W. DL all, Supervisor, Health Physics / Chemistry

• 0. Fraser, Supervisor, Site Safety Audit and Engineering Review

• E. Gibson, Supervisor, Reactor Engineering

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• G. Goode, Manager, Engineering Support

• J. Hammonds, Supervisor, Regulatory Compliance B. Hunt, Nuclear Fuels (Birmingham)

• W. Kiskley, Manager, Health Physics / Chemistry

• D. Read, AGM-PS Other licensee employees contacted during this inspection included engineers, operators, technicians, and administrative personnel.

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Nuclear Regulatory Commission

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B. Holbrook, Resident Inspector

• L. Wert, Senior Resident Inspector

• Attended exit interview

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Acronyms and Initialisms used throughout this report are listed in the last paragraph.

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Background (92700)

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The inspector discussed the issue of leaking fuel in Unit 2 with cognizant licensee representatives. Plant Hatch experienced fuel failure due to crud-induced localized corrosion prior to 1988. However, no i

corrosion-related failures had been experienced since 1988. The licensee attributed this performance to the 1989-90 replacement of the condenser tubes with those made of a titanium alloy.

The licensee was using GE 78 and GE 9B barrier fuel. The inspector was told that six different plants industry-wide had experienced fuel failure attributed to debris fretting since 1990 (in addition to the current condition of

Plant Hatch).

Prior to 1990, fuel failure due to debris fretting was much less common.

During Fuel Cycle 10, elevated levels of offgas radioactivity were noted and flux tilt evaluations of the core were performed.

Flux suppression and rod shadowing techniques were used on the suspect fuel cells to reduce offgas radiation levels.

Later, however, the radiation levels

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rose again, indicating additional failed fuel. During Refueling Outage 10, the full core was sipped and inspected. Three leaking fuel rods

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were discovered. Two of the bundles were de-channeled and inspected.

One of the bundles contained what appeared to be machining debris and a fretting-induced clad failure.

The licensee randomly selected twenty-five bundles for inspection and found debris in three of them. At that time, the licensee concluded that a potentially serious fuel problem

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existed and formed a Fuel Task Force to, among other duties, assure that necessary work activities were performed in such a way as to minimize the potential for future fuel damage resulting from debris. The Fuel Task Force conducted an extensive investigation of the situation to determine the source of the debris and concluded thet it was carbon

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steel introduced into the Primary Loop during machining activities performed during the previous refueling outage. The licensee inspected all of the fuel designated to be loaded in the core and removed all observed debris.

In addition, the licensee initiated corrective actions to prevent the introduction of foreign material into systems connected to the Primary Loop, with an emphasis on machining and flushing operations.

During the current fuel cycle (Cycle 11), increased radioactivity levels

in the reactor coolant system and offgas were detected on February 26, 1993, during a weekly surveillance. An increase in radioactivity levels of the offgas from March 1 to March 3, 1993 caused the licensee to shutdown on March 3, 1993. Although the radioactivity levels were below Technical Specification (TS) limits, they had reached levels which impacted work activities in the Turbine Building.

Fuel sipping was done on all fuel bundles and one failed fuel rod was identified. Debris similar to that found during the previous refueling outage was observed in the bundle and appeared to be the cause of the fuel failure. The unit was returned to Operations on April 6, 1993. On April 13, 1993, the unit was operating at near capacity when offgas radioactivity levels increased, indicating additional leaking fuel.

(Refer to Paragraph 2.d of Inspection Report 50-321,366/93-06.)

Power was reduced to 55 percent of capacity and a flux tilt of the reactor core was performed which determined that one of the four fuel bundles associated with control rod 46-23 was the leaker.

At the time of the inspection, Unit 2 was operating at 85 percent of capacity and the licensee continued to carefully monitor the Reactor Cool ant system (RCS) and offgas for indications of additional failed fuel rods.

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Offgas System Review (92700)

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The inspector reviewed the Offgas System for design capacity and operability. The Offgas Treatment System was designed to process and

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control the release of gaseous radioactive wastes to the site environs

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such that the total radiation exposure to individuals outside the controlled area is as low as reasonably achievable (ALARA) and does not exceed applicable regulations. Section 11.3.3.2 of the Final Safety Analysis Report (FSAR) states that the Offgas Holdup Line must be sized to accommodate system flow of between 4 and 40 standard cubic feet per minute (scfm). This will assure that the relatively short-lived non-condensible gaseous radionuclides (principally the activation gases of N-16, 0-19, and N-13) which are continuously removed from the main condenser by the air ejector during plant operations are held up for a

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minimum thirty minute duration which will allow thco to decay, thereby

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i reducing the amount of radioactivity released. The inspector reviewed

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the following drawings; 6511-2010-502 525252B, Rev. O, "Off Gas System Process Diagram" and two associated Process Data Sheets; H-26045, Rev. 30, "Off Gas System P&lD;" and H-260ll, Rev. 20, " Process Radiation Monitoring System P&ID, Sheet 1" for a clear understanding of the system components and their configuration. A radiation monitor (Equipment No. J005) placed downstream of the offgas condenser continuously monitors radioactivity released from the reactor and, therefore, can be

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used to indicate and identify fuel leakage as well as the radioactivity input to the charcoal adsorbers while another radiation monitor (Equipment No. J013) placed at the outlet of the charcoal adsorbers continuously monitors radioactivity released from the adsorber beds and can isolate the system on a high radioactivity alarm to prevent treated gas of unacceptably high activity from entering the main stack.

The inspector reviewed maintenance records (in the form of summarized Maintenance Work Orders (MW0s) as supplied by a corr; uter printout) of the two radiation monitors for the past several years to determine if any unusual or chronic problems were evident. Since 1987, there had been six MW0s written for the Pre-Treatment Off Gas Monitor involving items such flow meters, the isolation manifold, and solenoid valves.

Since 1985, there had been nine MW0s written for the Post-Treatment Off

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Gas Monitor involving items such as the vacuum pump, gauge replacement, and the reinstallation of an indicator lamp. No significant or chronic

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problems were noted by the inspector for either of the monitors.

The inspector reviewed the most recent linearity check for the Pre-Treatment Off Gas Monitor (done on October 6, 1992) for both chonnels and found them to be satisfactory. The inspector also reviewed the most recent source calibration setpoint record for the Post-Treatment Off Gas Monitor (done on March 29,1993) for both channels and found them to be satisfactory.

The licensee had observed system flow of about 5 to 6 scfm and felt that

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it was too close to the lower flow limit. To assure system operability,

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the licensee injected oxygen into the system on June 6, 1993 using Chemistry Control Procedure 63CH-0PS-001-0S, "0xygen Injection for Offgas Flow Determination," Rev. O, effective June 4, 1993, until the system flow was slightly over ten scfm. The inspector reviewed the work package for completeness and found no irregularities. Upor, completion of the oxygen injection, air was injected into the system to maintain flow at about ten scfm.

4.

Review of Radioactivity Levels, Releases, and Doses (92700)

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The inspector reviewed a graphical summary of dose levels as recorded by

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the Unit 2 Offgas Monitor for Fuel Cycles 10 and 11 for trends and comparisons.

For Cycle 11, an-increasing bias was evident from about

400 millirem per hour (mrem /hr) in mid-December 1992 to about 700 mrem /hr in 1 ate February 1993. A spike of about 1750 mR/hr developed in early March 1993 and another of about 750 mrem /hr developed i

in mid-April (after the unit had been re-started), clearly identifying when the fuel began to leak.

In the first instance, the licensee

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shutdown th, reactor while in the second the licensee reduced power to under 60 percent and evaluated the situation. DEI-131 showed a magnitude of increase from about 3.25E-3 micro-Curies per gram (pci/g)

on February 26, 1993 (at power prior to increases ir the radioactivity levels) to about 2.60E-2 gCi/g on March 3,1993 (at power, pre-shutdown).

In both cases, the TS limit of 2.0E-1 gCi/g was not challenged. Similarly, the pretreatment " Sum of Six" (the noble gases

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of Xe-133, Xe-135, Xe-138, Kr-85, Kr-87, and Kr-88) showed about a three-fold increase from about 2.75E+4 Ci/sec on February 26, 1993 to

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7.55E+4 pCi/sec on March 3, 1993. Again, the TS limit of 2.4E+5 Ci/g was not challenged.

Activity released and estimated doses due to gaseous releases for the third and fourth quarters of 1992 and first quarter of 1993 are

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summarized in Attachment 1.

(The 1992 information was obtained from the last Semiannual Effluent Release Report and the 1993 information was obtained from preliminary data from the licensee which will be used in the preparation of the next Semiannual Effluent Release Report.)

Review of the data found that the behavior of the Unit 2 data closely paralleled that of Unit 1, i.e. when the Unit I data dropped below (or

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rose above) that of the previous point, the Unit 2 data did likewise.

The most noticeable difference in the data was that the data of Unit 2 was generally of a greater magnitude than that'of Unit 1; specifically by a factor of 2 to 3 for dose estimates to as much as eight-fold in the case of particulate activity. Activity due to fission and activation gases and iodines as well as the whole body dose estimates were similar.

In terms of percent of TS limits, the Unit 2 noble gas gamma dose of the third quarter (before any fuel failure problems) represented the maximum of the data reviewed at 3.83% of its 5 mrad quarterly limit.

For the first quarter of 1993 (when the fuel failure occurred, resulting in the dose level spike of 1750 mrad /hr), the Unit 2 critical organ dose represented 3.03% of its 7.5 mrem quarterly limit.

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Conclusions (92700)

Upon completion of the review of the referenced information, the inspector concluded that the licensee's program was adequate to control effluents in the presence of damaged fuel. The Off Gas System was well-maintained and its monitors were calibrated and could isolate the system under non-routine conditions.

~.ne Holdup System was capable of meeting i

its minimum thirty minute holdup requirement.

Gaseous releases and their associated estimated doses were well within TS limits; the maximum estimated dose over the previous three calendar quarters was slightly under four percent of the limit.

In addition, the licensee had written new work procedures to prevent any foreign debris from entering the Primary Loop with the potential of causing fretting fuel failures.

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Exit Interview (92700)

The inspection scope and results were summarized on June 11, 1993, with those persons indicated in Paragraph 1.

The inspector described the areas inspected and discussed the inspection results, including likely I

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informational content of the inspection report with regard to documents and/or processes reviewed during the inspection. The licensee did not identify any such documents or processes as proprietary. Dissenting comments were not received from the licensee.

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Acronyms and Initialisms ALARA - As Low As Reasonably Achievable Ci

- curie FSAR - Final Safety Analysis Report g

- gram GE

- General Electric Company hr

- hour pCi

- micro-Curie (1.0E-6 Ci)

mrad - milli-Rad mrem - milli-rem MWO

- Maintenance Work Order No.

- Number P&ID - Piping and Instrumentation Diagram RCS

- Reactor Coolant System Rev

- Revision scfm - standard cubic feet per minuts i

TS

- Technical Specification

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ATTACHMENT 1

Hatch Radioactive Gaseous Release Sq,amary 1992 1992 1993 3rd Q 4th Q 1st Q Activity Released (curies)

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l Unit 1 1. Fission and Activation Gases 1.54E+2 1.05E+2 2.26E+2 2. Iodines 1.46E-2 1.76E-3 1.74E-2 3. Particulates 1.04E-3 2.64E-4 7.52E-4 Unit 2 1. Fission and Activation Gases 2.67E+2 1.08E+2 1.98E+2

2. Iodines 2.73E-3 1.13E-3 1.65E-2 3. Particulates 9.95E-4 2.14E-4 5.59E-3

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Dose Estimates from Gaseous Effluents

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Unit 1 1. Noble Gas Gamma Dose.(mrad)

8.79E-3 7.77E-3 1.15E-2 2. Noble Gas Beta Dose (mrad)

1.17E-2 1.13E-2 1.47E-2 3. Critical Organ (mrem)

3.73E-2 7.21E-3 8.54E-2

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4. Whole Body (mrem)

3.11E-3 2.27E-3 6.48E-4 Unit 2

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1. Noble Gas Gamma Dose (mrad)

1.91E-1 3.48E-2 2.62E-2 2. Noble Gas Beta Dose (mrad)

1.42E-1 3.03E-2 3.12E-2 3. Critical Organ (mrem)

4.13E-2 1.23E-2 2.27E-1 i

4. Whole Body (mrem)

4.58E-3 3.33E-3 8.06E-4 i

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