United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 82-32: Contamination of Reactor Coolant System by Organic Cleaning Solvents

                                                            SSINS No.: 6835 
                                                            IN 82-32 

                               UNITED STATES 
                       NUCLEAR REGULATORY COMMISSION 
                    OFFICE OF INSPECTION AND ENFORCEMENT 
                          WASHINGTON, D. C. 20555 

                              August 19, 1982 

Information Notice No. 82-32:   CONTAMINATION OF REACTOR COOLANT SYSTEM 
                                   BY ORGANIC CLEANING SOLVENTS 

Addressees: 

All nuclear power reactor facilities holding an operating license (OL) or 
construction permit (CP). 

Purpose: 

This information notice is provided as a notification of an event that may 
have safety significance. It is expected that recipients will review the 
information for applicability to their facilities. No specific action or 
response is required at this time. 

Description of Circumstances: 

on April 24, 1982, while at full power, the Hatch Unit 1 plant experienced a 
rapid increase in water conductivity in the condensate, feedwater, and 
primary reactor systems. This was accompanied by increasing radiation 
readings on the main steam line and offgas monitors. Operations personnel 
began an orderly power reduction at 1430 CST. By 1730 CST, with the reactor 
power at 35%, the reactor water conductivity had exceeded the Technical 
Specification limit of 10 micromhos per centimeter. The plant was manually 
scrammed at 1930 CST. At 19 hours into the event the conductivity peaked at 
21 micromhos per centimeter. At this time the chloride level in the reactor 
water, which also had been increasing, peaked at 2.5 ppm and the pH had 
dropped to 5.1. The Hatch Technical Specification limits for these values 
are 0.5 ppm for chlorides and greater than 5.2 for pH. A local power range 
monitor (LPRM) detector failed within 9 hours of the start of the event and 
by 48 hours into the event, 35 LPRM detectors had failed. This event 
resulted in a plant outage of more than than 1 month. 

After an extensive investigation, the licensee identified the cause of the 
problem as contamination of the reactor coolant by trichloroethane. This is 
an organic solvent (purchased under the trade name of "MOMAR Electrosafe"), 
used for cleaning and decontamination at Hatch. MOMAR is a nonconducting, 
nonionic cleaning agent for electrical equipment. The trichloroethane is 
believed to have been present in the turbine building equipment drain sump 
before the event. A leaking valve resulted in the overflow of water from a 
condensate demineralizer system which also flowed into the same drain sump. 
The sump pump automatically started and transferred the sump water along 
with the trichloroethane into the radwaste collector tank. This water was 
processed by the waste cleanup system and after routine sampling was 
transferred into the condensate storage tank and then back to the reactor. 
.

                                                           IN 82-32 
                                                           August 19, 1982  
                                                           Page 2 of 2 

The trichloroethane, being nonionizing, was not removed by the resins in the
radwaste demineralizers. Furthermore, the normal demineralized water 
sampling methods, which largely depend on measuring the conductivity of the 
water, did not detect the nonconducting trichloroethane. The licensee was 
able to show, however, that the solvent breaks down and becomes ionizing 
(and conducting) in the presence of heat and radiation. A mixture of 1 
milliliter of solvent per liter of water, having an initial conductivity of 
1.75 micromhos per centimeter, increased in conductivity to 1580 micromhos 
per centimeter when heated to 200F and irradiated in the fuel pool for 
30 minutes. The chloride ion concentration in the mixture also rose from 
0.025 ppm to 22.5 ppm. 

In addition to investigating the cause of the contamination and to cleaning 
the reactor water, the licensee took the following action in response to the
event: 

     Four fuel assemblies were removed, examined, and returned to the 
     reactor. 

     One control rod blade was removed, examined, and retained for future 
     detailed examination. 

     All LPRM strings were removed and some were sent to GE for 
     determination of the failure mode. 

     Plans were made for the establishment of procedures to analyze for 
     organic carbons in plant water systems. 

     An evaluation of the effect of the event on the reactor coolant system 
     was included in the long-range inservice inspection program. 

These actions required about 40 days to accomplish. Although no problems 
were identified during preliminary visual examination of the fuel and 
control rod blade, the examination of the control rod blade and the LPRMS is 
continuing. Further, the licensee is establishing procedures to analyze for 
organic carbons in plant water systems. Prompt detection of organics such as
trichloroethane would have prevented the incident and avoided the lengthy 
outage. 

No written response to this information is required. If you need more 
information about this matter, please contact the Regional Administrator of 
the appropriate NRC Regional Office or this office. This event is also the 
subject of INPO Significant Event Report 30-82, titled "Intrusion of 
Cleaning Solvents (Organic) Into Reactor Coolant System. 


                              Edward L. Jordan, Director 
                              Division of Engineering and 
                                Quality Assurance 
                              Office of Inspection and Enforcement 

Technical Contact:  D. C. Kirkpatrick 
                    (301) 492-4510 

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