ML20086H705
| ML20086H705 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 07/01/1975 |
| From: | Cooney M PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Anthony Giambusso Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20086H708 | List: |
| References | |
| AO-75-50, NUDOCS 8401200125 | |
| Download: ML20086H705 (3) | |
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,e PHILADELPHIA ELECTRIC COMPANY 2301 M ARKET STREET
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PHILADELPHI A. PA.19101
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taisi e43 4ooo pu JUL7 iiii July 1, 1975
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'[\\#q.,. L-Mr A. Giambusso f
E Director Division of Reactor Licensing Of fice of Nuclear Reactor. Regulations United States Nuclear Regulatory Commission Washington, DC 20555
Dear Mr. Giambusso:
Subject:
Abnormal Occurrence The following occurrence was reported to Mr. Jim P.artlow, Region 1, Office of Inspection and Enforcement, United States Nuclear Regulatory Commission on June 22, 1975 Written notification was made to Mr. James P. O'Reilly, Region 1, Of fice of Inspection and Enforcement, United. States Nuclear Regulatory Commission on June 23, 1975 In accordance with Section 6 7 2.A of the Technical Specifications, Appendix A of DPR-M for Unit 2 Peach Bottom Atomic Power Station, the following occurrence is being submitted to the Directorate of Reactor Licensing as an Abnormal Occurrence.
Reference:
License Number DPR-44 Technical Specification
Reference:
3 8.A Report No.:
50-277-75-50 Report Date:
July 1, 1975 Occurrence Date:
June 21, 1975 Facility:
Peach Bottom Atomic Power Station R.D. 1, Delta, Pennsylvania 17314 Identification of Occurrence:
Unplanned release of contaminated water to the discharge canal.
Conditions Prior to Occurrence:
Unit 2 in cold shutdown.
Description of Occurrence:
During investigation of a suspected tube leak in the "D" RHR heat exchanger, there was apparently some migration of reactor water into the High Pressure Service Water System side of the hoot exchanger. As soon as a leak was identified, the heat exchanger was removed from service and isolated.
8401200125 750701 PDR ADOCK 05000277 8
Mr. A. Giambust 50-277-75-50
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July 1,1975 Page 2 Designation of Apparent Cause of Occurrence:
Tube leak in
'D' RHR Heat Exchanger.
Analysis of Occurrence:
J The High Pressure Service Water System is operated.at nominal 20 PSI above the Residual Hest Removal System when operated in the shut-down cooling mode. The HPSW System is the first one placed in service and the 'last one removed from service in the shutdown cooling made.
When shutdown cooling operation is terminated the Rit1 ' system is isolated from the reactor and when the HPSW Pump is removed from service the HPSW discharge valve to the canal automatically closes. A control room annunciator monitors for proper differential pressure when both systems are used in the shutdown cooling mode. All operations, interlocks, and annunciators are aimed at precluding a release of contaminated water to the plant discharge canal.
As soon as a heat exchanger leak was identified, the RHR and HPSW loops were removed from service and both sides of the RHR heat exchanger were isolated. Abodt an hour later, chere was a slight rise observed in two of the plant's process liquid monitors count race. This was quickly determined to be shine from the rdjacent HPSW system supply water line to the 'D' RHR heat exchanger. 00 serving the inherent mixing of reactor water and High Pressure Service Water inside the isolated boundaries, with both systems shutdown, it was decided to surf ace sample tra discharge canal at the point of-entry of the HPSW line. The purpose of this sample was to verify that no unplanned liquid release had occurred, due to inherent mixing of the two fluids in the heat exchanger, when the systems were shutdown, prior to the leak identification.
The surface sample at the point where the HPSW line enters the circulating water discharge indicated less than minimum detectable activity.
As a matter of course, a second sample was taken at the same location several hours later and indicated approximately 4 x 10~7 Ci/ml.
This was the first indication that an unplanned release had occurred.
A more compreher.sive sampling program was initiated to quantify the extent of the release.
The specific activity of a surf ace sample taken at the plant point of discharge several hours af ter the RHR heat exchanger was isolated indicated a specific activity of 7 7 x 10~
Ci/
ml.
Since the shutdown cooling oper.stion with the Icaking heat exchanger and the sampling program were in different time frames, it is difficult to quantify the magnitude of.the release, except to say that it was minor in nature. The heat exchanger had only one leaking tube and there was no driving force to mix the reactor water into HPSW when both systems were shutdown except diffusion through the Icak.
It is,
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C)50-277-7$-50
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Mr. A. Gi ambuss,'
July 1, 1975 Page 3
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therefore, unlikely that a significant quantt ty of reactor water leaked into the HPSW side of the exchanger.
Adopting the ul tra-conservative, but physically impossible, position that all of the reactor water in the isolated shutdowa cooling loop were released to the river through the leaking tube the total re-lease would still have been only 17 percent of the quarterly Technical Specification liquid release limit for that unit, From scrutiny of the sample analysis data, it is estimated that the release was actually a few orders of magnituoe less than that. Therefore, there is minimal sarety significance associated with this occurrence.
Corrective Action:
The defective tube was plugged. A design modification was implemented, which plugs a total of four tubes in a high inlet water impingement area.
Failure Dsta:
None previous.
Very truly yours, M, J.
ooney Ass't Gen'l Superinten ent Generation Division ec:
Mr. J. P. O'Reilly Director, Region i Of fice of Inspection and Enforcement United States Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406 s
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