Efforts to Reduce Radiation Exposure at the Takahama Power Station Takahama Power Station Kansai Electric Power Co.

Overview of Takahama PS Unit 1 826MW Started in November 1974 Unit 2 826MW Started in November1975 Unit 3 870MW Started in January 1985 Unit 4 870MW Started in June 1985 Osaka Kansai Wakasa ○Fukui Japan １

Current Levels of Radiation Exposure in Japan ２ Radiation exposure in Japan is at higher levels than in other major countries. （出典： ISOE Annual Report 2006 ） Dose per LWR Germany Japan Sweden U.S. France Finland Swiss Belgiu m Spain （ Source: ISOE Annual Report 2006 ） Dose (man Sv/unit) Comparison by Reactor Type (PWR) Germany Japan U.S.France Dose (man Sv/unit) （ Source: ISOE Annual Report 2006 ）

３ Doses at Takahama are almost leveling off, with some ups and downs depending on what jobs were involved in each refueling outage. History of Doses at Takahama PS

４ Formation of a Working Group to Address Radiation Exposure Reduction Our exposure reduction efforts include improvement of water chemistry, automation of work, and work management with attention to details. In addition, we have started dose reduction efforts from a different viewpoint, focusing on reducing doses transmitted/received between different work activities. These efforts are led by a newly organized “working group (WG) for radiation exposure reduction.” 1. Objective 2. Organizational Structure of the New WG New WG Organization for Exposure Reduction Manager of Radiation Management Section of Kansai Kanden Plant Kanden Power Tech Mitsubishi Heavy Ind. (Administrative Office) To achieve exposure reduction in a more efficient and effective way, contractors are included in the WG as they are well-versed in outage work activities and in work areas. This WG works under the supervision of the Manager of Radiation Management Section of the power station and leads exposure reduction activities on a station-wide basis from Unit4 18th refueling Outage in 2008.

５ Study of Measures to Reduce Radiation Exposure 【 In considering measures for exposure reduction 】 Study was made with focus on the following two areas. To further reduce radiation exposure, the above two focus areas were selected for the WG to study effective ways to reduce exposure. 1. Reduction from the viewpoint of environment 2. Reduction from the viewpoint of outage work activities Remove radiation source by injecting zinc while the plant is on-line Adjustment of schedule for draining SG secondary water Installation of temporary shielding Assessment of Radiation Effects Installation of portable shielding

６ Specific Actions for Reducing Exposure at Takahama (1) 1. Remove radiation source by injecting zinc while the plant is on-line (1) How zinc injection works Ｚｎ＞Ｃ ｏ Zinc bonds to chromite (CR2O4) more strongly than cobalt. Being more energetically stable than cobalt, zinc displaces cobalt from the oxide layer (especially in the inner layer: chromite). Once in the oxide layer, zinc exists in a stable condition, preventing additional cobalt entry. Zinc displaces Co. Zinc prevents pickup of Co. Oxide layer Pipe base metal Zinc is more easily taken into the oxide layer (inner layer : chromite) than cobalt.

７ Specific Actions for Reducing Exposure at Takahama (2) (2) Effects of zinc injection (1/2) Zinc injection has decreased dose rates as shown above. b. Dose equivalent rates from SG channel head center (average of A,B and C) and RV head (Unit 4) Dose rate(mSv/h) c. Dose equivalent rates from RCS pipe surface ( average of A,B and C ) (Unit 4) Dose rate (mSv/h) Refueling outage number zinc injection started Dose rate （ mSv/h ） Hot leg R/V head (flange center line) Zinc injection started Cold leg Refueling outage number Crossover leg Zinc injection started Hot leg Cold leg Dose rate （ mSv/h ）

８ Specific Actions for Reducing Exposure at Takahama (3) (2) Effects of zinc injection (2/2) Radiation exposure reduction in main jobs Zinc injection successfully reduced doses from main jobs as shown above. Dose reduction for SG isolation ＝ 31.7% （ Dose 2008/dose 2007 =68.3%) Dose reduction for SG isolation ＝ 31.7% （ Dose 2008/dose 2007 =68.3%) Dose reduction for SG tube inspection = 26.9% （ Dose 2008/dose 2007 =73.1%) Dose reduction for SG tube inspection = 26.9% （ Dose 2008/dose 2007 =73.1%)

９ 2. Adjustment of schedule for draining SG secondary water Specific Actions for Reducing Exposure at Takahama (4) Adjust outage work schedule to minimize the period during which SG secondary side is in a drained condition. ① Identify jobs that require this condition of SG and minimize their periods. 【 Work titles 】 elimination of SG sludge, Repair of SG sampling pipe, C-SG BEC inspection （ It was shortened for three days altogether. ） ② Execute works without blow out of period during blow of secondary water in SG 【 Work titles 】 Annual inspection of RCP seal, Annual inspection of RCP motor ③ Schedule the draining to take place at a time when not many workers are around SG. 【 A-loop 】 : September 24 to October 6 → October 13 to October 25 【 B-loop 】 : September 13 to September 24 → September 30 to October 12 【 C-loop 】 : September 19 to October 2 → October 7 to October 25 Adjust outage work schedule to minimize the period during which SG secondary side is in a drained condition. ① Identify jobs that require this condition of SG and minimize their periods. 【 Work titles 】 elimination of SG sludge, Repair of SG sampling pipe, C-SG BEC inspection （ It was shortened for three days altogether. ） ② Execute works without blow out of period during blow of secondary water in SG 【 Work titles 】 Annual inspection of RCP seal, Annual inspection of RCP motor ③ Schedule the draining to take place at a time when not many workers are around SG. 【 A-loop 】 : September 24 to October 6 → October 13 to October 25 【 B-loop 】 : September 13 to September 24 → September 30 to October 12 【 C-loop 】 : September 19 to October 2 → October 7 to October 25 The most effective means to reduce radiation exposure is to make use of the shielding effect of water, by keeping secondary water in the SG. Exposure reduction is possible by minimizing the period during which SG secondary side is in a drained condition.

10 Specific Actions for Reducing Exposure at Takahama (5) 3. Installation of temporary shielding To be placed in areas where many workers are around, to avoid radiation from high-dose pipes and other components. 【 Shielding material 】 (1) Temporary shielding 【 Shielding installed on- site 】 床面 High-dose pipes Shielding material

11 Specific Actions for Reducing Exposure at Takahama (6) (2) Effects of the temporary shielding (work area dose equiv rate) This shielding is used at places close to radiation sources, making dose rates in large areas around the shielding from 20% to 40% low. Effective for workers moving around Center of radiation source To RV To Wall

12 Specific Actions for Reducing Exposure at Takahama (7) The WG prepares and presents to workers the Info of “Assessment of the Environ Surrounding the Work Area” (see Pages 13 and 14) a.Assessment of the Environment Surrounding the Work Area → Perspective of giving effects RP personnel review radiation effects from various tasks using the “Radiation Exposure Reduction Assessment ”(see Page 15 and 16 ) and study how to avoid them. b. Radiation Exposure Reduction Assessment → Evaluate preventive measures from the perspective of receiving effects 4. Assessment of Radiation Effects Outline of the assessment For the current (2008) outage, this Assessment has been applied on a trial basis only to the major jobs performed by the three contractors included in the WG.

13 Specific Actions for Reducing Doses at Takahama (8) Assessment of the Environ Surrounding the Work Area During a refueling outage, many different work activities take place in the same work area, resulting in workers receiving doses not only from their own work but from others’. The WG gives workers advance information about when, where, and by how much dose rates are expected to increase during the outage – Info of assessment of the environ surrounding the work area. Assessment of the Environ Surrounding the Work Area -1

14 Specific Actions for Reducing Exposure at Takahama (9) Assessment of the Environ Surrounding the Work Area -2

15 Specific Actions for Reducing Exposure at Takahama (10) Radiation Exposure Reduction Assessment (Review of radiation effects from other activities and measures to mitigate the effects)-1 No action needed Minor job? Work in CV? Near temporarily stored VH? In area where SG elbow removed? Work performed concurrently? Same as above Around SG? In C loop RM? Around RCP motor In B, C loop RMs? Work performed concurrently? Work at CV 32m O/F? Work in loop RM at CV 26, 24m? Work on passage (btwn A and B ENT) at CV17m? Work in loop RM at CV 21m? Work in loop RM at CV 17m? In B, C loop RMs? Work performed concurrently? Hot leg or cold leg? Work performed concurrently? In B loop RM? Work performed concurrently? ：Y：Y ：N：N Job name: Annual Inspection of RCP seal Effects after action （ mSv ） 実施時期変更作業場所変更作業位置変更 （ｍＳｖ） （変更後の実施時期）（変更後の作業場所） 高線量箇所遮へい携帯式簡易遮へい （ ○○ から ○ ｍ移動） （待機場所 ○○ ） 作業者の向き・姿勢 作業手順変更材料内作化他 LCI lift up/ down VH temp storage SG elbow separation SG main body SG water draining SG HH opening RCP motor, on SG side SG manhole MCP branch pipe nozzle High dose pipe Radiation effects SG manhole IP High dose pipe/ com Crossover leg pipe draining RCP motor transfer Pipe sections removed due to cavity flow Work on SG manhole IP at B-loop ENT CVCS pipe on ceiling Actions to avoid risk AlternativesMitigation Effects from 遮へい措置短縮化に工法変更作業者配置変更 Same as above Alternatives 1.Change work schedule 2. Change work area Mitigation: 1.Install shielding 2. Change the work location 3. Change workers’ position/posture 4. Shorten the work duration by changing the way work is done Installation of portable shielding to the side of SIS pipes Estimated Dose level after action:9.39(30%reduction) Installation of temporary shielding on the grated floor above the cold leg pipe Estimated Dose level after action:7.3(35%reduction) Avoidance the period during which SG secondary side is in a drained condition Installation of temporary shielding to the side of SG

16 Specific Actions for Reducing Exposure at Takahama (11) Radiation Exposure Reduction Assessment (Review of radiation effects from other activities and measures to mitigate the effects)-2 No action needed Minor job? Work in CV? Near temporarily stored VH? In area where SG elbow removed? Work performed concurrently? Same as above Around SG? In C loop RM? Around RCP motor In B, C loop RMs? Work performed concurrently? Work at CV 32m O/F? Work in loop RM at CV 26, 24m? Work on passage (btwn A and B ENT) at CV17m? Work in loop RM at CV 21m? Work in loop RM at CV 17m? In B, C loop RMs? Work performed concurrently? Hot leg or cold leg? Work performed concurrently? In B loop RM? Work performed concurrently? ：Y：Y ：N：N Job name: Annual Inspection of RCP Motor Effects after action （ mSv ） 実施時期変更作業場所変更作業位置変更 （ｍＳｖ） （変更後の実施時期）（変更後の作業場所） 高線量箇所遮へい携帯式簡易遮へい （ ○○ から ○ ｍ移動） （待機場所 ○○ ） 作業者の向き・姿勢 作業手順変更材料内作化他 LCI lift up/ down VH temp storage SG elbow separation SG main body SG water draining SG HH opening RCP motor, on SG side SG manhole MCP branch pipe nozzle High dose pipe Radiation effects SG manhole IP High dose pipe/ com Crossover leg pipe draining RCP motor transfer Pipe sections removed due to cavity flow Work on SG manhole IP at B-loop ENT CVCS pipe on ceiling Actions to avoid risk AlternativesMitigation Effects from 遮へい措置短縮化に工法変更作業者配置変更 Same as above Alternatives 1.Change work schedule 2. Change work area Mitigation: 1.Install shielding 2. Change the work location 3. Change workers’ position/posture 4. Shorten the work duration by changing the way work is done Installation of portable shielding to the side of SIS pipes 6.1 Estimated Dose level after action:4.27(30%reduction) Installation of temporary shielding on the grated floor above the cold leg pipe Installation of temporary shielding to the side of SG 6.1

17 5.Simplified, portable shielding Specific Actions for Reducing Exposure at Takahama (12) (1) Shielding material 【 Shielding material 】 【 How to use the shields 】 Lead shield Frame of a scaffolding WG estimated where to install shields within radiation exposure reduction assessment. And WG members advised way of more effective use while patrolling the working field. Effective for still workers

18 Specific Actions for Reducing Exposure at Takahama (13) (2) Portable shields installed on-site Exposure Dose is about 0.03mSv for attaching shields.( under 0.1mSv/h Condition) Exposure Dose is about 0.03mSv for attaching shields.( under 0.1mSv/h Condition)

19 Specific Actions for Reducing Exposure at Takahama (14) Effects of temp shielding and portable shielding on exposure reduction Because of radiation exposure reduction assessment, Comparison of dose data between the 2007 outage and the 2008 outage has verified the effects of these two types of shielding. Effects of Radiation Exposure Reduction Assessment

Conclusion The recent efforts for radiation exposure reduction have been made in collaboration with the Radiation Management/Radiation Protection Departments of main contractors, under the supervision of the station top management. Each of the parties has provided insights from their own perspectives, feeling that “we are one.” This has led to a station-wide awareness towards radiation exposure reduction, promoting discussions involving all parties concerned. This seems to be a favorable side effect of the recent efforts. With Unit 4 still in a refueling outage, the final evaluation is yet to be made on the effects of the temporary shielding and Radiation Exposure Reduction Assessment. In the meantime, we will check the progress in outage work activities, track the effects of the measures in place, and discuss and implement improvements to further promote radiation exposure reduction efforts. 20

THE END