ML20087L626

Ao:On 740125,auxiliary Bldg Stack Monitor R-14 Alarmed Indicating Release of Radioactivity.Caused by Increased Pressure Attained in Holdup Tanks & Suction of Waste Gas Compressors

ML20087L626
Person / Time
Site:	Point Beach
Issue date:	02/06/1974
From:	Burstein S WISCONSIN ELECTRIC POWER CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 8403270308
Download: ML20087L626 (4)

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231 WEST M10HIGAN, MILWAUKEE, WISCONSIN 53201 1[j'.[ 8 o E February 6, 1974 Mr. John F. O' Leary, Director Directorate of Licensing U. S. Atomic Energy Commission Washington, D. C. 20545

Dear Mr. O' Leary:

m DOCKET NOS. 50-2J6 AND 50-301 UNSCHEDULED RELEA n OF RADIOACTIVITY POINT BEACH NUCLEAR PLANT This letter is to report the details of an abnormal occurrence at Point Beach Nuclear Plant, Facility Operating License Non. DPR-24 and DPR-27, as defined by Sections 15.1.a.C and 15.1.a.G of the Technical Specifications. This written re-port is submitted in accordance with Section 15.6.6.A.2 of the Technical Specifications and follows a telephone report on the incident to Mr. Ed Jordan of Region III, Directorate of Regula-Lory Operations on January 29, 1974, as required by Section ,

15.6.6.A.1 of the Technical Specifications.

At approximately 2200 hours0.0255 days <br />0.611 hours <br />0.00364 weeks <br />8.371e-4 months <br /> on January 25, 1974, R-14 the auxiliary building stack monitor, alarmed indicating release of radioactivity (alarm setpoint - 6,000 counts per minute). An investigation was initiated immediately.- An operation to pump the spent fuel pit transfer canal to the "B" holdup tank was in pro-gress at that time. The rising level of liquid in the holdup tank raised the normal 2 psig gas pressure in the bank to approximately 5 psig. This temporarily higher pressure extended to the suction of the waste gas compressor; the running compressor taking this gas and pumping it to the gas decay tanks. The volume control tank area (an area of a previous gas leakage problem) was inves-tigated first. This investigation took several shift periods with no success in finding leakage. The CVCS holdup tanks were examined closely for any physical signs of leakage as well as the waste gas compressors and their associEted piping.

Since no signs of leakage were found, the holdup tank'.s relief valves were suspect for leakage. These valves-are hard-piped and therefore not capable of being visually checked. With this possibility in mind, the removal of excess pressure in the CVCS holdup tanks was continued in order-to remove what was be-lieved to be a probable source of auxiliary building leakage.: -

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Mr. John F. O' Leary February 6, 1974 This did not decrease the radiation levels and the detailed search continued. On January 29, 1974, an investiga-tion of the waste gas cryogenic cubicle was initiated when two men received surface contamination of their clothing in that area. The cryogenic unit is located within the radiation con-trolled area of the plant but this equipment has not yet com-pleted its functional test program and has not been operated using radioactive gases to date. Therefore, personnel contami-nation in this area was an unexpected occurrence. The source of the contamination was quickly found and isolated.

During the preoperational inspection of relief valve protection on the plant's new radwaste spstem on November 26, 1973, the State boiler inspector requested the immediate removal of two relief valves for examination. The examination disclosed that the two one-half inch relief valves did not comply with State code requirements and the inspector advised that the valves be replaced with approved relief valves before placing the new system into service. Under the pressure of the inspection and in view of the fact that this system had not yet been placed in service, holes left by the removed valves were not capped or isolated and the removal of the valves was not recorded as an

" unusual plant condition", as required by Point Beach Adminis-trative Procedure PBNP 4.17, " Lifted Wires, Jumpers and By-passes". The relief line has since been cut and capped with a Swagelok fitting and has been red tagged to prevent removal of the cap until such time as this system is ready for opera-tional service.

The relief valves in question vent the cryogenic com-pressors to the suction of the waste gas compressors via valve 2-980A, a normally locked open valve. Removal of the valves provided a path for gas to flow in the opposite direction, i.e.,

gas compressor suction to cryogenic unit; then to atmosphere in the cryogenic cubicle. .

The length of piping through which the path of the re-lease ran is approximately 240 feet of 3/4 inch pipe, with another 145 feet of 5/8 inch stainless steel tubing. It is be-lieved that the length of this path and the normally low pres-sure in the CVCS holdup tanks kept the release to an undetec-table minimum during normal operation. The cause of the detec-table release was the increased pressure attained in the holdup tanks and suction of the waste gas compressors during the pump-ing down of the fuel transfer canal.

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t Mr. John F. O' Leary F ebruary 6, 1974 The release was continuously monitored throughout by the auxiliary building stack monitor and the attached calcula-tions show that the release was well below allowable limits as set by 10 CFR 20. Therefore, it is not considered that this occurrence posed a health or safety hazard to the public.

All involved personnel have been reminded of the im-portance of following existing operating and administrative procedures; this care to be extended to all plant equipment irrespective of its operational status.

Very truly yours,

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Sol Burstein Execu ive Vice President Enclosure 4

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-e l RELEASE OF 1-25-74 TO 1-28-74 ,,

l. Total activity released - 171.6 Ci.

a. Use a daily hourly average of 6049 cpm. which is equal to 2.2 x 10-5 pCi/cc concentration from the calibration curve for the auxiliary building stack monitor R14.

b. Total period of release - 75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br />.

c. Total flow during release period - 7.8 x 10 12 cc. llh

d. ( 1 ) (2.2 x 10-5 pCi/cc) (7.8 x 10 12 cc) = 171.6 Ci 1 x 10' pCi/Ci

2. Activity released by isotope based upon MPC for unrestricted areas:

Concentration Fraction Curies at Site Boundary  % MPC at Released MPC UCi/cc Site Boundary Isotope of Total

-10 Xr-88 .045 7.772 2 x 10 8 4.29 x 10 -10 2.2 Xr-85m .032 5.491 1 x 10-67 3.05 x 10 0.3 Xe-135 .696 119.433 6.635 x 10-9 6.6

.227 38.953 1

3 x x 10 10-7 2.164 x 10-9 0.7 Xe-133

3. Total activity released as Xc-133 equivalent - 529.555 Ci. llI Isotope Equivalent As Xe-133 Xr-88 15 115.83 Ci Xr-85m 3 16.473 Ci Xe-135 3 358.299 Ci Xe-133 1 38.953 Ci c

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