U.S. Nuclear Regulatory Commission
Contamination of Nonradioactive System and Resulting Potential for Unmonitored, Uncontrolled Release of Radioactivity to the Environment
HPPOS-079 PDR-9111210213
Title: Contamination of Nonradioactive System and
Resulting Potential for Unmonitored, Uncontrolled Release
of Radioactivity to the Environment
See IE Bulletin No. 80-10 entitled as above and dated May
6, 1980. Action Item 3 of this bulletin states that if a
nonradioactive system becomes contaminated and it is
considered necessary to continue operation, an immediate
safety evaluation must be performed in accordance with 10
CFR 50.59.
An auxiliary boiler had been operated for an extended
period of time with contaminated water containing up to
2x10-2 micro-Ci/ml. The contamination was caused by a tube
leak in a temporary hose connecting the auxiliary boiler to
a radioactive waste evaporator concentrate tank. Upon
cooling and condensation of steam in the hose, contaminated
water siphoned from the concentrate tank back to the
auxiliary boiler. Because of additional and continuing
leaks in the heat exchanger of the waste evaporator, the
licensee's efforts to decontaminate the auxiliary boiler
feedwater were ineffective. Maintenance of proper boiler
chemistry was difficult because blowdown options were
restricted due to contamination. As a result, 100 mCi of
radioactive material were released off-site in steam via
the auxiliary boiler fire box and smokestack. The release
resulted in increased environmental levels of cesium and
activation products being detected eight miles downwind
from the site boundary.
Actions to be taken by licensees with operating licenses to
preclude the described situation include:
1. Review facility design and operations to identify
systems considered as nonradioactive (or described as
nonradioactive in the FSAR) that may become contaminated by
radioactive systems. Consideration should be given to the
following: auxiliary boiler system, demineralized water
system, isolation condenser system, PWR secondary water
clean-up system, instrument air system, and sanitary waste
system.
2. Establish a routine sampling / analysis program for
these systems to detect radioactive contamination.
3. If nonradioactive systems are or become
contaminated, further use of the system shall be restricted
until the cause is identified, corrected, and
decontaminated. However, if it is considered necessary to
continue operation with the contaminated system, an
immediate safety evaluation of the operation of the system
as a radioactive system must be performed in accordance
with the requirements of 10 CFR 50.59. The 10 CFR 50.59
safety evaluation must consider the level of contamination
and any potential releases of radioactivity to the
environment. The relationship of such releases to the
radioactive effluent limits of 10 CFR 20
[§§20.1001-20.2401], the facility's Technical
Specifications, and to the environmental radiation dose
limits of 40 CFR 190 must also be evaluated. The record of
the safety evaluation must set forth the basis and criteria
on which the determination was made.
4. If it is determined in the 10 CFR 50.59 safety
evaluation that operation of the system as a radioactive
system is acceptable, provisions must be made to comply
with the requirements of 10 CFR 20.201 [or, at present, 10
CFR 20.1501], General Design Criterion 64 to 10 CFR 50,
Appendix I to 10 CFR 50, and the facility's Technical
Specifications. Specifically, any potential release points
must be monitored and all releases must be controlled and
maintained to ALARA levels described in 10 CFR 50 Appendix
I and within the corresponding environmental dose limits of
40 CFR 190. If in the 10 CFR 50.59 determination it is
concluded that operation of the system as a radioactive
system constitutes an unreviewed safety question or
requires a change to the Technical Specifications, the
system shall not be operated as contaminated without prior
commission approval.
Regulatory references: 10 CFR 50.59
Subject codes: 5.0, 7.3, 9.2
Applicability: Reactors
