Report on Fact-finding Meeting by Diablo Canyon Independent Safety Committee (DCISC) at Diablo Canyon Power Plant (DCPP) on October 25 @ 26, 2006 by Per F. Peterson, Member and R. Ferman Wardell, Consultant [17th Annual Report, Exhibit D.3]

1.0 Summary

The results of the October 25-26, 2006 Fact-finding Trip to the Diablo Canyon Power Plant in Avila Beach, CA are presented. The subjects addressed and summarized in Section 3 include:

  1. Observe October 25, 2006 NRC-Graded Emergency Exercise
  2. Use of Best Estimate Analyzer for Core Operations - Nuclear (BEACON)
  3. Use of Outage Risk Analyzer – Maintenance (ORAM)
  4. Security Update
  5. Emergency Preparedness Update
  6. New Control Rod Worth Test
  7. Tour Independent Spent Fuel Storage Installation (ISFSI) Construction
  8. DCISC Member Meeting with DCPP Management

2.0 Introduction

This Fact-finding Trip to the DCPP was made to evaluate specific safety matters for the DCISC. The objective of the evaluation was to determine if PG&E’s performance is appropriate and whether any areas revealed observations which are important enough to warrant further review, follow-up, or presentation at a public meeting. These safety matters include follow-up and/or continuing review efforts by the Committee, as well as those identified as a result of reviews of various safety-related documents.

Section 4 – Conclusions highlights the conclusions of the Fact-finding Team based on items reported in Section 3 – Discussion. These highlights also include the team’s suggested follow-up items for the DCISC, such as scheduling future Fact-finding meetings on the topic, presentations at future public meetings, and requests for future updates or information from DCPP on specific areas of interest, etc.

Section 5 – Recommendations lists specific recommendations to PG&E proposed by the Fact-finding Team. These recommendations will be considered by the DCISC. After review and approval by the DCISC, the Fact-finding Report, including its recommendations, is provided to PG&E. The Fact-finding Report will also appear in the DCISC Annual Report.

3.0 Discussion

3.1 Observe October 25, 2006 NRC-Graded Emergency Exercise

The DCISC Fact-finding Team met with Steve Hamilton, Regulatory Services Engineer, to observe the October 25, 2006 NRC-Graded Emergency Exercise. The DCISC has a special interest in DCPP performance in emergency drills, especially in providing clear, timely and accurate information to the media and public. The DCISC last observed a DCPP emergency exercise in December 2004 (Reference 6.1). The DCISC concluded in its 2004-2005 Annual Report (Reference 6.2) the following from that drill:

The two emergency exercises performed during the reporting period showed PG&E’s strengths in operationally mitigating, managing and recovering from emergency events at DCPP. The process and performance of providing clear, accurate, and timely emergency information to the media and public at the Joint Media Center has improved; however, PG&E has recognized that it needs to further improve the way it conveys radiation release projections and data to the media and public, and also improved coordination with the County. This aligns with recent DCISC positions and recommendations, and the DCISC will closely follow PG&E’s progress in this area.

The DCISC had the following recommendation in its 2004 – 2005 Annual Report (Reference 6.2):

PG&E should consider using one designated Lead Public Spokesperson, an officer, for all of its media briefings on emergency information to the media and public at the Joint Media Center. Because a specific person cannot be available at all times, backup personnel also need to be designated and trained. PG&E should work with both San Luis Obispo County and the State of California to improve the clarity and precision of their statements regarding radiation releases. This is necessary to assure that information on projected and measured offsite dose rate measurements by PG&E and County monitors are more clearly communicated to the media and public.

DCPP responded as follows to this recommendation:

DCPP recognizes the value of having an officer available to speak at media briefings, when appropriate. All Diablo Canyon Officers are qualified as Emergency Response Recovery Managers and are available to participate in media briefings at the Joint Media Center. However, some of the briefings may not need an officer, and in those instances, other individuals will continue to provide timely and accurate information to the media. Nevertheless, the extent to which officers are involved with media briefings will be increased. The clarity and precision of statements regarding radiation releases are extremely important. DCPP’s objective is to provide timely and accurate information. While we have worked with the county and state to continually improve the clarity of our communication and responses, we agree that radiation release statements could be further clarified. DCPP will share this recommendation with the county and state and continue to work with them to ensure communication is clear and precise.

The DCISC determined this response was acceptable.

DCPP provided the DCISC Fact-finding Team with the exercise scenario prior to the beginning of the exercise. A summary of the scenario is as follows:

The DCISC Fact-finding Team (FFT) began its observation in the control room simulator (CRS) which was acting as the Control Room for the exercise. The CRS was fully staffed with the following individuals:

In addition to the FFT, there were numerous controllers, NRC observers, and a consultant hired by DCPP for two weeks to advise on operator error prevention, procedure adherence, and status control.

The FFT observed the tsunami warning and Loss of Offsite Power and Notifications of Unusual Event and Alert, along with preparations for notification of appropriate Federal, State and local agencies. All declarations and notifications were performed correctly and timely. The operators used the proper procedures for the situation and demonstrated good error-prevention practices: three-way communication, phonetic alphabet, status updates, and diagnostic tailboards. The FFT observed the declaration of the LOCA-caused Site Area Emergency and subsequent operator tailboard prior to going into the appropriate Emergency Procedure. Demeanor in the CRS appeared calm and professional. In addition to the normal instruments and controls, the CRS contained a split-screen video conference monitor showing the CRS, Technical Support Center (TSC), Emergency Offsite Facility (EOF), and JMC representatives for communication (mostly status update) purposes.

The FFT then went to the Technical Support Center (TSC) which had been properly activated and was fully staffed. Paul Roller, former Operations Director, was acting as Site Emergency Coordinator in the TSC. The TSC contained a split-screen video conference monitor for four-way communication similar to that in the CRS. There were status boards throughout the TSC for events, major equipment status, and action priorities (e.g., restore 500 kV power to Unit 1, make the RWST operable, energize vital bus, site evacuation, on-site and off-site radiological monitoring, etc.). There were other boards, displays and monitors in the TSC for engineering and radiological information. The FFT observed the report of core T/C temperatures >1200@deg; F, declaration of the General Emergency, and initial preparation of agency notifications. The TSC demeanor appeared calm and professional. The noise level, which the DCISC had previously found to be high, was moderate and not apparently bothersome.

The FFT traveled to the EOF, located at the SLO County Sheriff’s Office. The EOF had dedicated space for both DCPP and SLO recovery organizations, as well as NRC, CA State and FEMA representatives. The Unified Dose Assessment Center (UDAC) was located in the EOF. UDAC is a joint DCPP/County organization which analyzes and reports plant radioactive releases and resulting actual and projected radiation levels in areas around and downwind of DCPP. All organizations in the EOF appeared to have been activated properly and timely and were functioning well. The EOF contained many status boards and monitors, e.g., radiation dose assessment (plume and dose projections), event status, PAR status, radiological Field Monitoring Team (FMT) status, Protective Action Zone (PAZ) maps and wind direction, etc. DCPP conducted regular updates and tailboards.

The FFT went to the JMC to observe media briefings and receive event news releases. The JMC was fully staffed with DCPP, SLO County, and CA Governor’s Office personnel. In typical news media briefings the SLO County Public Information Officer (PIO) discussed protective actions (sheltering and evacuations); DCPP personnel reported on plant status and mitigation activities and releases; and the CA Governor’s representative reported on State assistance and a declaration of a state of emergency.

The News Releases appeared accurate and well-worded. In the early parts of the exercise the following statement was used routinely by DCPP:

“No release of radioactive material to the environment from this event, as indicated by sensitive plant radiation monitors. Under NRC regulations, nuclear power plants are permitted to release very small amounts of radioactive material during operations, which have no public impact. These releases are strictly limited, measured, and below naturally occurring background levels of radiation which are present throughout the environment and can be measured anywhere.”

The County’s news releases stated the following:

There is no threat to the general public at this time and no action by the public is necessary.

or

A radioactive material release is not occurring.

When the simulated radioactive release began, the DCPP news releases were written as follows:

At this time there is a release of radioactive material to the environment, as indicated by plant radiation monitors. The projected dose from the release will be at levels that require public protective actions as determined by San Luis Obispo County. At 1:06 pm today, a dose of 8 mR/hour was measured by a field monitoring team at the site boundary, about ½ mile from the plant. This would be the exposure to an individual if they remained at the site boundary, and the release continued at the same level for one hour.

[The news release originally stated “three” hours but was corrected to “one” hour in a later news briefing. It is noted that the unit of radiation dose is given in abbreviated form (mR), while below it is defined and discussed as millirem. A person who is not technically trained would not likely know that mR is the abbreviation for millirem.]

Based on atmospheric conditions, the plume of radioactive material tends to dissipate as it moves away from the plant. Currently, the plume is heading in a NNW direction. Therefore, any radiation exposure beyond PG&E’s property likely will be significantly lower than radiation exposures at the plant site boundary.

Radiation dose is measured using the Rem. The Rem is the standard unit that measures the effects of radiation on people. A millirem equals one-thousandth of a rem. In the United States, the average citizen will receive about 300 millirem of radiation dose per year from natural and man-made sources. For example, the radiation dose a person would receive from a medical chest X-ray ranges from 20 to 50 millirem, or from a round-trip, cross-country air flight, four millirem. People also receive radiation dose from natural sources including plants, minerals in the ground, and radon gas.

The County’s news release stated:

At this time there is a release of radioactive material to the environment.

The DCPP and County news releases appeared informative, accurate and timely. DCPP’s news releases concentrated on plant status, mitigation efforts, and radioactive releases. The county provided information on protective actions, emergency broadcasts, schools, and agricultural actions. The news releases appeared useful and informative.

DCPP spokespersons consisted of an Emergency Public Information Manager (EPIM) who provided general plant emergency overview information; a Technical Spokesperson who provided technical aspects of the emergency and mitigation actions; and a Radiological Spokesperson who provided reports of releases and actual and projected doses downwind of the plant. DCPP employees participated as “mock media” with questions at each briefing. The “media” had many questions on the radiological aspects of the event. Response to these questions was spotty, in that some radiological information was useful (actual and projected dose rates at various locations downwind of DCPP), but there were some responses of “I don’t have that information” or “I don’t know” in which it appeared to the FFT that the information was available and should have been known. Commitments to provide information in subsequent briefs went unfulfilled. There were similar instances in which State and DCPP radiological experts did not appear to have been using the same information or became too technical about radiation effects and Potassium Iodide (KI). Clear, timely radiological information from DCPP and the State/County has been a previous concern of the DCISC.

As it has stated in previous reports on DCPP emergency drill observations, the DCISC FFT believes that the use of a single spokesperson, preferably an officer, would improve providing messages to the media. This is because officers are generally more experienced at providing information in a concise, mostly non-technical, and contextual manner. One high-level spokesperson can provide more consistency and better handle questions than several less experienced speakers. Officers are elected by Boards to officially represent the organization and are perceived by media and public as such. DCPP has agreed with this approach on an “as needed” basis (see DCPP response to DCISC recommendation above). Jim Becker, Vice President and Plant Manager, appeared at the JMC but in a limited role.

The FFT observed the JMC critique following the end of the event. The critique focused on whether DCPP met its previously-stated objectives. Generally, all objectives were met or “met with comment”. In the latter case, DCPP participants believed that (1) some information on radiation releases and levels was not timely, (2) spokespersons didn’t consistently respond to media questions or provide promised follow-up information, and (3) at times too much technical information was provided. The FFT reported that it agreed with that assessment and that during media briefs, DCPP and County and State personnel appeared disjointed in that they weren’t using the same radiological information and became too technical at times, confusing the audience. The FFT believed that the critique was effective overall.

Following the exercise, DCPP reported that NRC concluded that DCPP “effectively demonstrated the ability to implement its Emergency Plan” and did not identify any issues not already identified by DCPP. FEMA provided favorable comments regarding DCPP, State, and County performance.

Conclusion:
The October 25, 2006 DCPP emergency preparedness exercise appeared to have been well-designed and challenging. DCPP appeared to have effectively implemented its Emergency Plan during the exercise and performed a good critique. Two areas of DCISC concern were (1) difficulty in providing timely, accurate and understandable information on radiation releases to the media and public and (2) little or no use of a DCPP officer to represent the organization to the media and public.

3.2 Use of Best Estimate Analyzer for Core Operations - Nuclear (BEACON)

The DCISC Fact-finding Team met with Shane Guess, an Engineer in the Reactor Engineering Group, to discuss DCPP’s use of BEACON (Best Estimate Analyzer for Core operations – Nuclear). This is the DCISC’s first review of BEACON.

BEACON is a Westinghouse-developed analytical tool for predicting the power distribution in a reactor core. It is significantly more accurate than previous modeling tools because it includes a detailed model for fuel burn up that predicts with high accuracy the changing isotopic and elemental composition of the fuel due to fission and neutron capture reactions. Confirming that the reactor core power distribution remains inside design limits is important for safety, because during a design basis accident initial fuel damage would occur at the locations in the core with higher than average power. DCPP uses BEACON to augment the functional capability of the incore flux mapping system above 25% full power for the purpose of Technical Specification required power distribution surveillances. Westinghouse submitted the BEACON topical report to the NRC and received approval in 1994. The NRC concluded that it provided a greatly improved continuous online power distribution measurement and operation prediction information system. DCPP submitted its specific application to the NRC in mid-2003 and received approval in 2004.

DCPP uses BEACON for the following specific purposes:

  1. Reactor Core Power Distribution Measurement vs. Flux Map – a calibrated BEACON power distribution monitoring system calculates peaking factors (required by Technical Specifications every 31 Effective Full Power Days [EFPD]) without the need for an incore flux map.
  2. Reactor Ramp Planning: BEACON’s load swing calculation allows for the Reactor Engineer to calculate predicted volumes of boric acid and primary water during a power ramp and also to predict delta-I behavior for Operations.
  3. Other: Reactivity Balances, Reactor Shutdown Margin calculation, Estimated critical Condition calculation, and Single-Point calibration.

BEACON is initially calibrated using incore flux measurements. These are obtained from the plant movable Incore Detector System. It includes an online three dimensional nodal model that is continuously updated to reflect the current reactor operating conditions. The power distribution calculation used in core monitoring is updated with core exit thermocouple measurements each minute. BEACON utilizes a surface spline fitting technique to interpolate/extrapolate the incore flux detector measurements and thermocouple measurements to unmeasured fuel assemblies. The neutronics calculations used by BEACON solve the classic diffusion equation which describes the nuclear behavior of the reactor core. Calibration with the incore detectors is required every 180 EFPD.

The core exit thermocouple and excore neutron flux detector measurements are used with the reference 3-D power distribution to determine the measured power distribution. If BEACON becomes unavailable, the movable incore detector system can be used. The continuous BEACON monitoring feature (of such parameters as fuel burnup, Xenon distribution. Soluble Boron, etc.) permits instantaneous identification of core anomalies and predictive capabilities for both operators and reactor engineers.

Being used for safety-related applications, BEACON falls under the Software Quality Assurance Program (SQAP). A cycle-specific version is verified each restart following a refueling outage. DCPP considers BEACON to be very accurate; however, it has exhibited a slight delay in reaction to boration and slight additional amounts of boration than predicted. This is likely caused by an approximate 13% core bypass of injected boric acid due to injection and letdown point geometry.

The FFT reviewed a July 1, 2006 100% - 90% - 100% Power Unit 2 Cycle 14 Ramp Plan created by DCPP Reactor Engineering using BEACON. The plant was being ramped down for Digital Feedwater System testing at 90% power. The plan had been requested by Operations. The plan stated clearly that it was to be used as a guidance tool, not to be considered operating limits nor used a script. The plan was used in a pre-job Operations brief prior to beginning the ramp down operation. The plan provided a suggested timeline, ramp rates, process hold points, control rod operation, and predicted boric acid additions and primary water additions. Included were timeline graphs. The Ramp Plan appeared to be a useful tool for Operations.

One potential future benefit of BEACON is in improving the power ascension schedule. Normally, during power ascension, BEACON is calibrated with an incore flux map at 28%, 48%, and 100% power. The flux map can take as long as 28 hours to stabilize due to Xenon to equalize, creating a hold point. With BEACON it is possible to reduce that by 12 hours at the 48% point and 6-12 hours at 100%. The flux map calibration must be performed at 28% power.

Conclusion:
DCPP’s use of the Best Estimate Analyzer for Core Operations – Nuclear (BEACON) appears to be an effective and safe alternative for reducing the need to use of the Movable Incore Detector System (MIDS) to perform the Technical Specification required reactor core power distribution measurement every 31 Effective Full Power Days. Use of BEACON in the industry and at DCPP has been approved by the Nuclear Regulatory Commission.

3.3 Use of Outage Risk Analyzer – Maintenance (ORAM)

The DCISC Fact-finding Team met with Nathan Barber, Reactor Engineering Group Engineer, to review DCPP’s use of Outage Risk Analyzer – Maintenance (ORAM). The DCISC last reviewed the use of ORAM in On-Line Maintenance in September 2005 (Reference 6.3) at which time it concluded:

DCPP uses Probabilistic Risk Analysis (PRA) and ORAN to determine when to do on-line maintenance. They perform all Technical Specification (TS) required Preventive Maintenance (PM) and testing on-line and in general, they plan to perform work on a piece of equipment that takes only 50% of out-of-service time allowed by TS. It appears that PG&E is using the proper selection process to perform on-line maintenance of equipment.

ORAM is a work-station-based logic program incorporating DCPP Probabilistic Risk Assessment (PRA) data which is used to determine the risk of various plant equipment outage combinations during plant operation. DCPP has Train Level System, Structure @ Component (TLS) codes for its risk-significant work items, typically equipment that is to be out-of-service (OOS) for maintenance. ORAM reads the TLS Codes and assesses risk using PRA tables and Safety Function Assessment Trees (SFATs). ORAM output consists of risk colors (green/yellow/orange/red) assigned based on quantitative PRA criteria as well as Key Safety Assessment (KSA) scores. Operations Shift Manager approval is required for the following situations which will show Orange risk:

Plans showing Red risk color must be reviewed and approved by the PRA Group. DCPP runs ORAM each day with the daily work plan. Because ORAM is used for safety-related applications, it is included in the DCPP Software Quality Assurance Program.

The FFT reviewed a sample ORAM risk chart for the outage of Emergency Diesel Generator (DG) (EDG) 1-3 and Residual Heat Removal (RHR) Pump 1-1. Overall risk was Orange for an outage time of 183.0 hours, whereas each individual equipment outage was Yellow. The Core Damage Frequency was 6.499E-005 per reactor year. The risk chart appeared to be a useful tool to assure plant risk is minimized and with acceptable limits.

ORAM is also used to calculate outage risk assessment. The FFT reviewed an Outage Risk Assessment chart. The chart graphed Core Damage Risk per Hour against time for various plant equipment configurations. In this example, relatively higher risk was shown for the two Refueling Outage procedure in which, after shutdown and a cooling period, reactor coolant is lowered below the hot and cold legs, permitting work to be performed in a relatively dry environment. The operation is a relatively high-risk condition due to the potential for loss of cooling.">mid-loop operations following shutdown and prior to startup. The highest risk was calculated to be in the range of 1E-09 to 1E-08 per hour (acceptable) for the duration of Refueling Outage procedure in which, after shutdown and a cooling period, reactor coolant is lowered below the hot and cold legs, permitting work to be performed in a relatively dry environment. The operation is a relatively high-risk condition due to the potential for loss of cooling.">mid-loop operation. The risk for other outage operations was less than 1E-15 per hour.

In the second quarter of 2007 DCPP plans to replace ORAM with a new program, Safety Monitor, from the Electric Power Research Institute (EPRI). DCPP is presently testing the program and verifying interfaces. It can calculate risk from more than two components OOS, whereas ORAM is limited to two. It also has the capability to include environmental (e.g., controlled burning near off-site power lines) and test factors and allows for a more accurate assessment of trip risks. Safety Monitor can perform risk calculations based on the full DCPP PRA.

DCPP is currently working on its quantitative PRA shutdown model which is scheduled to be complete in late 2008. (The Fire Protection PRA is expected to be complete by the end of 2007). When completed, the updated quantitative shutdown model will be incorporated into Safety Monitor and used for shutdown risk assessment. In the meantime, the quantitative ORAM shutdown model will continue to be used.

Conclusion:
DCPP’s use of the Operating Risk Analyzer – Maintenance (ORAM) for determining the risk of equipment outages for maintenance during operation and for risk estimates during outages appears appropriate. It determines when management approvals are required for relatively higher risk plant evolutions. DCPP will be replacing ORAM with Safety Monitor which has more capabilities and which will provide more accurate and detailed shutdown risk assessments.

3.4 Security Update

[Note: due to the sensitivity of nuclear plant security, information classified as “Safeguards Information” cannot be presented in this report, thus limiting the breadth and scope of the report. Both Dr. Peterson and Mr. Wardell have been cleared for access to DCPP Safeguards Information.]

The DCISC Fact-finding Team met with Bob Zimkowski, Security Manager; Sean Dienhart, Security System Projects and Compliance; and Jeff Hartley, Security Operations Manager, for an update on DCPP Security. The DCISC last reviewed Security in May 2006 (Reference 6.4) when it concluded the following:

The Security Force-on-Force drill observed by the DCISC appeared successful in all aspects: meeting drill objectives, personnel safety and plant safety. The DCPP Security Team appeared professional and capable. Safety risks associated with conducting the exercise outside and inside the plant were comprehensively identified and minimized during the exercise, so that the exercise achieved its security goals while maintaining appropriate plant and personnel safety levels.

DCPP Security appears to be satisfactorily implemented. Based on the successful Force-on-Force Drill, Security appears to be a capable, well-equipped organization.

Along with DCPP, Security is working at being “the best” in the industry and is working on identifying performance gaps to close to meet that goal. These gaps include personnel safety, human performance, equipment issues, facilities, work/life balance, and cost. Plans are being developed to improve performance in these areas and to move from “White” to “Green” performance in the Quality Performance Assessment Report (QPAR).

Major plans and activities include the following:

@#8226; Project and Outage Support

@#8226; Regulatory Performance and Security Procedures

@#8226; Security System/Locks @ Keys

@#8226; Oversight and Planning

DCPP expects a Force-on-Force drill in late 2006 or early 2007 and will advise the DCISC for possible attendance.

The DCISC has reviewed Security equipment issues in previous Fact-finding meetings. Most of the equipment problems have been with search trains, cameras and detection equipment. Security is taking the following actions to assure good equipment performance and reliability:

Security has already seen the monthly Action Request backlog for equipment corrective action reduced from approximately 150 to 55-60.

Recent NRC inspections and Quality Verification assessments have found no significant issues. QPAR rates Security as having “White” performance and improving.

Conclusion:
DCPP Security appears satisfactory with a “White” Quality Performance Assessment Report rating. Security has goals and plans for achieving Quality Performance Assessment Report (QPAR) “Green” and of becoming the best in the industry.

3.5 Emergency Preparedness Update

The DCISC Fact-finding Team met with Mike Meko, Director Station Services, for an update on DCPP Emergency Preparedness (EP). The DCISC last reviewed EP in May 2006 (Reference 6.5) when it concluded the following:

DCPP has been experiencing an increase in failures of equipment needed by the Emergency Plan and has developed a procedure to provide compensatory measures and actions to develop a Long-Term Emergency Plan Equipment Reliability Improvement Plan, and an Emergency Preparedness Five-Year Strategic Plan. These are positive actions which the DCISC should monitor on a regular basis.

Because of perceived low priorities, Emergency Preparedness (EP) was having difficulty obtaining engineering and maintenance support to improve its equipment reliability, except for Technical Specification and other similarly important items; however, EP is working with Security, which is having similar problems, to develop a joint solution. There have been no results to date. EP is developing leads for its facilities (e.g., Technical Support Center, Emergency Offsite Center, Joint Media Center, etc.) to assure attention to their needs. Overall, EP equipment and facilities are in a stable condition but not improving.

EP will continue its normal drill schedule in 2007 and work on improvements for 2008. It is developing a five-year comprehensive EP plan in late 2006 or early 2007. The plan will address all open EP issues and needed improvements and, along with DCPP, work toward becoming the best in the industry. Included in the plan will be actions to address the recent biennial EP assessment (Reference 6.5). The DCISC should continue to follow DCPP EP plans and actions.

Conclusion:
DCPP Emergency Preparedness appears generally satisfactory, and NRC performance indicators are currently all Green; however, there are equipment reliability, facility, and staffing issues. DCPP is developing action plans for dealing with these issues. The DCISC should continue to follow these plans.

3.6 New Control Rod Worth Test

The DCISC Fact-finding Team met with Ken Kargol, Engineer in Reactor Engineering, to discuss the new Control Rod Worth Test. This is the first review of this test.

Technical Specification-required control rod worth, subcritical negative reactivity, and Moderator Temperature Coefficient (MTC) testing is performed during each start-up from a Refueling Outage in which fuel changes are routinely made, i.e., approximately one-third of the core is replaced with new fuel. Typically, testing has been performed at hold points during power ascension requiring approximately 24 hours of outage time. A new process developed by Westinghouse shortens the required outage time to approximately 7.5 hours or less for an outage savings of about 17.5 hours. Control rod drop testing is still required. The new test is controlled by Procedure STP R-50, MODE 3 Physics Testing dated May 13, 2006.

The new process is Subcritical Physics Testing (SPT) based on Westinghouse Subcritical Rod Worth Measurement (SRWM) methodology. SPT is performed when the reactor is subcritical rather than at power in conventional testing. The SPT Program consists of the following three measurements:

  1. Total Control and Shutdown Rod Bank Worth
  2. All Rods Out (ARO) Critical Boron Concentration
  3. Isothermal Temperature Coefficient (ITC)

The total bank rod worth and ARO critical boron measurements are performed in parallel with the withdrawal of the control and shutdown rod banks. The rod banks are withdrawn for the required measurement of the rod drop times at nominal Hot Zero Power (Mode 3) reactor temperature and pressure. At the ARO condition, an additional hold is added to the rod drop time measurement procedure to allow the reactor coolant temperature to be decreased approximately 5@deg; F to allow the measurement of the ITC. Unlike the more conventional reactor verification testing performed using signals output from a Power Range detector, the SPT does not require removing a protection system input from service, saving time and avoiding a degraded reactor protection system.

The results of the measurements exhibited good agreement with core design predictions as follows:

DCPP and Westinghouse considered these results to be excellent and sufficient to provide enough confidence to allow power operation to commence. Additionally, DCPP reported excellent agreement between the predicted and measured Inverse Count Rate Ratio (ICRR) values.

Conclusion:
DCPP’s new reactor physics testing procedure accurately measures core parameters, saves over 17 hours of outage time, and permits measuring Technical Specification-required reactor core parameters without removing any reactor protection inputs, resulting in a safer configuration.

3.7 Tour Independent Spent Fuel Storage Installation (ISFSI) Construction

The Fact-finding Team met with Bruce Patton, ISFSI Project Engineer, to tour the ISFSI construction site. The DCISC last toured the site in May 2006 (Reference 6.6). In that report the DCISC concluded the following:

A tour of construction of the foundation of the pad for the initial spent fuel storage casks of the Independent Spent Fuel Storage Installation (ISFSI) revealed orderly and well-controlled work in-progress.

The DCISC has been following the progress of the ISFSI since its beginnings. The tour included excavations and concrete pours for foundation of the pad which will hold the initial set of casks and the pad for the cask transfer station. Additionally, the hillside above the pads has been stabilized to prevent dirt and rock slides onto the pads. Construction work appeared orderly and well-controlled. Personnel safety was apparent in that all who went on the construction site were required to wear high-visibility vests to assure they were visible to heavy equipment operators. The Team inspected two Holtec casks which will be used to hold the spent fuel when it is placed onto the ISFSI concrete pads.

Conclusion:
A tour of construction of the foundation of the pad for the initial spent fuel storage casks of the Independent Spent Fuel Storage Installation (ISFSI) revealed orderly and well-controlled work in-progress.

3.8 DCISC Member Meeting with DCPP Management

DCISC Member Per Peterson met separately with Donna Jacobs, Vice-President Nuclear Services, to discuss items reviewed in this Fact-finding meeting and other items of interest to the Committee.

4.0 Conclusions

4.1
The October 25, 2006 DCPP emergency preparedness exercise appeared to have been well-designed and challenging. DCPP appeared to have effectively implemented its Emergency Plan during the exercise and performed a good critique. Two areas of DCISC concern were (1) difficulty in providing timely, accurate and understandable information on radiation releases to the media and public and (2) little or no use of a DCPP officer to represent the organization to the media and public.
4.2
DCPP’s use of the Best Estimate Analyzer for Core Operations – Nuclear (BEACON) appears to be an effective and safe alternative for reducing the need to use of the Movable Incore Detector System (MIDS) to perform the Technical Specification required reactor core power distribution measurement every 31 Effective Full Power Days. Use of BEACON in the industry and at DCPP has been approved by the Nuclear Regulatory Commission.
4.3
DCPP’s use of the Operating Risk Analyzer – Maintenance (ORAM) for determining the risk of equipment outages for maintenance during operation and for risk estimates during outages appears appropriate. It determines when management approvals are required for relatively higher risk plant evolutions. DCPP will be replacing ORAM with Safety Monitor which has more capabilities and which will provide more accurate and detailed shutdown risk assessments.
4.4
DCPP Security appears satisfactory with a “White” Quality Performance Assessment Report rating. Security has goals and plans for achieving Quality Performance Assessment Report (QPAR) “Green” and of becoming the best in the industry.
4.5
DCPP Emergency Preparedness appears generally satisfactory, and NRC performance indicators are currently all Green; however, there are equipment reliability, facility, and staffing issues. DCPP is developing action plans for dealing with these issues. The DCISC should continue to follow these plans.
4.6
DCPP’s new reactor physics testing procedure accurately measures core parameters, saves over 17 hours of outage time, and permits measuring Technical Specification-required reactor core parameters without removing any reactor protection inputs, resulting in a safer configuration.
4.7
A tour of construction of the foundation of the pad for the initial spent fuel storage casks of the Independent Spent Fuel Storage Installation (ISFSI) revealed orderly and well-controlled work in-progress.
5.0 Recommendations:
None

6.0 References

6.1
“Diablo Canyon Independent Safety Committee Fourteenth Annual Report on the Safety of Diablo Canyon Nuclear Power Plant Operations, July 1, 2004 – June 30, 2005”, Approved October 12, 2005, Exhibit D.5, Section 3.1, “Observe December 8 [2004] Graded Exercise.
6.2
Ibid., Section 4.7.3.
6.3
“Diablo Canyon Independent Safety Committee Fifteenth Annual Report on the Safety of Diablo Canyon Nuclear Power Plant Operations, July 1, 2005 – June 30, 2006”, Approved October 18, 2006, Exhibit D.2, Section 3.10, “Implementation of On-Line Maintenance.”
6.4
Ibid., Exhibit D.10, Sections 3.6 “Security Force-on-Force Drill” and 3.8, “Security Update”
6.5
Ibid., Section 3.2, “Emergency Preparedness Equipment Reliability.”
6.6
Ibid., Section 3.5, “Tour of ISFSI Construction.”

For more information about DCISC contact:

Diablo Canyon Independent Safety Committee
Office of the Legal Counsel
857 Cass Street, Suite D, Monterey, California 93940
Telephone: in Califonia call 800-439-4688; outside of California call 831-647-1044
Send E-mail to: dcsafety@dcisc.org