Checked Binding

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  radioValue: 'one',
  
  display: Ember.computed('radioValue', function() {
    return JSON.stringify(this.get('radioValue'));
  }),
  
  actions: {
    modify(arg) {
      this.set('radioValue', arg.target.value);
    }
  }
});

helpers.eq.js

import Ember from 'ember';

export function eq(params) {  
  return params[0] === params[1];
}

export default Ember.Helper.helper(eq);

templates.application.hbs

<label><input type="radio" name="thing" checked={{eq this.radioValue "one"}} onchange={{action "modify"}} value="one"> one</label>
<label><input type="radio" name="thing" checked={{eq this.radioValue "two"}} onchange={{action "modify"}} value="two">two</label>

<hr />
{{display}}

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}